Twin turbo vs Supercharging LS motors? What's the vibe nowadays?

[Jag530G]

Something that I seem to have noticed in recent times is that we don't see many people talking about twin-turbos for LS motors anymore (although I see Duke5700 is doing a TT). When I first joined the forum there were quite a few posts about TT kits and installations, don't really see them anymore. I seem to notice more people going down the supercharging route of late using Harrop blowers or such like (Feistl's car as an example).

Are TTs are waning and the move is on towards S/C? If so, why? (or why not, if I'm completely barking up the wrong tree) Reliability? Better quality product ie a Harrop blower is a bit more of a known quantity then some TT kit put together? Fashion? GM support for S/C with LS9/LSA factory motors? Ford Coyote motor raising support for S/C?

Your thoughts are welcome.

Cheers, Matthew

[2010blackve]

Probably a lot of TT builds going on just not posted on here.

All depends on what people are trying to achieve.

I looked at both and tested both before my current combo, as my car is a street car I decided on the PD blower and built motor combo.

All comes down to personal preference.

[itsme4g63]

Supercharging is alot simpler than installing a twin turbo kit, you basically change out the intake sides and add a pulley bracket and youre almost done whereas turbocharging requires alot of pluming and parts removal, especially on V engine cars. This is why you always see oem's supercharging v8 motors and turbocharging 4 cylinders or inline motors.

[macca_779]

Supercharging is alot simpler than installing a twin turbo kit, you basically change out the intake sides and add a pulley bracket and youre almost done whereas turbocharging requires alot of pluming and parts removal, especially on V engine cars. This is why you always see oem's supercharging v8 motors and turbocharging 4 cylinders or inline motors.

Unless your BMW, Mercedes, Audi etc.

[IJ.]

I did the Turbo thing on other cars for 25 odd years even to the point that I used one on my L98 is the non Holden car a couple of years back, while I had a lot of success making very good power it always came at a cost, radiant heat... don't let anyone play this down it's a huge issue to contend with.

PD Blowers still generate heat but nothing like a Turbo system and have far fewer install issues to contend with, Modern Blowers have matured to the point their transparent in use and just "feel" like a much larger engine and can be almost silent depending on which you choose.

[bozodos]

Unless your BMW, Mercedes, Audi etc.

Isn't that more for emissions reasons rather than performance?

[macca_779]

Isn't that more for emissions reasons rather than performance?

Your kidding right... No

[SS317]

I went for the PD blower because I liked the easy install process (I fitted it myself) and the instant power even at low rpm, why'll a few of the TT cars I've been in have had insane power it always seems to be at a much higher rpm and this was not what I was after.

[feistl]

Hey,

This was my own personal reasoning for choosing S/C over TT (I am no way saying this is BETTER overall, just better for me personally).

1. When you start making serious power (400rwkw+) the spike in power from a turbo charged LS V8 can be pretty brutal and difficult to control (especially in low grip scenarios). A S/C has a very progressive power delivery from basically idle, so its a bit easier to stay at almost maximum power without breaking traction. Of course at the higher speeds this isnt so much an issue, but at anything less than ~150kp/h power delivery is important.

2. TT kits require a fair bit of cutting to accommodate the piping. This also usually means a big air to air intercooler at the front, which limits room for other coolers (For example say engine oil coolers, power steering/transmission coolers etc).

3. Engine bay temps can be pretty hot due to the extra piping, even with hpc coating everything tends to run a little hot for my liking.

I will be interested to see how well the HTV2300 works on the track for extended periods. Supposedly the charger is a bit too small for 427ci, although i dont plan to run a heap of boost so im hoping it copes.

Turbos are obviously capable of a lot more boost for the same sort of money, so if your after massive power its still the way to go.

Cheers

[itsme4g63]

I doubt a supercharger, at least a roots type like the tvs would hold up for track racing for extended periods of time beyond a few hotlaps. I’d imagine it would get heatsoaked sooner or later as it does sit right on top of the engine and the heat would just keep rising to it. If you fancy a supercharger for track racing I’d imagine a centrifugal type blower would suit the needs way more efficiently. Its setup like a turbo system as far as the intercooling goes and does sit next to the engine but is drven by a belt like the roots type so it never sits close to the exhaust as it needs to be placed parallel to the engine accessory pullies due to its drive belt system.

Foreign german car manufacturers like AUDI/BMW/Mercedes, aside from the fact that smaller boosted engine do help them passing emissions standards, invest millions/billions into new engine/turbocharger/platform development so they can mass produce them whilst gm would just try to adapt a turbo kit to an existing motor/platform (like they’ve adapted a supercharger to the cts-v/Camaro zl1/C6 ZR1) and be left with countless horrors of getting screwed over on possible warrantees if something was to go wrong. Its not that it can’t be done its just that I believe they’d consider it too costly.

I’d imagine one of the reasons the new LT1 motor is coming along is because GM might have it setup for some sort of turbocharging in mind though, which we might see in the future zr1 corvette. I’d if in anything else though, but if such a motor can fit in a ticght corvette engine bay, then it would without issues into many different cars.

[Solone]

i think the centrifugal supercharger system is ideal for a street ls1/2/3 motor.

You can drive it tame when you dont need to be on boost or plotting through traffic, getting reasonable fuel economy and generates almost no additional heat. Under about 3000rpm its like they are not there, so for most driving situations less stress on components. When you need power, you crack the throttle and get gobs full like a turbo. It dont hit as hard as a turbo or PD charger at 3000rpm which wont break or shock pistons/rods and less likely to overwelm street tyres. But it will build up a torrent of horsepower up top in an exponential fashion when you need it moreso than the PD blower and similar to turbo.

Also the higher comp LS motors dont really want peak boost at peak torque (max cylinder pressure) as this leads to detonation. But after this point cylinder pressure tails off and then can tolerate the boost. But how do you give a PD blower variable boost to best deal with this?

look at some of the bigger vortech units or procharger. Similar to turbo benefits, less heat and easier install.

[IJ.]

LOL Centri's have the worst of both camps...

TVS type blowers bypass at light throttle so aren't putting any more load than the Centri driving around but have the benefit of instant power soon as you get on the throttle.

[shaness8]

Com'on GM bring out a turbo LS motor and take euro's on.

[bozodos]

Your kidding right... No

I'd read it on several websites actually. Less parasitic loss from turbochargers and they act like mufflers as well to some degree.

[duke5700]

Personaly preference to some degree, including whoever installs them. A blower is a drive in drive out much quicker install than a turbo kit is. Generally speaking also a better install and cleaner.

A PD blower is a very instant power add, feels like driving a big block really. Turbos take time to spool and as such can feel pretty instant when they come but in all reality, good turbo design and boost control will make them feel almost lazy fast. I would much rather punt a turbo car around a race track than a big blown car. Easy to dial power in and out of and with todays boost controllers boost curves can be tailored wet/dry and to the track at the push of a button. A good traction control system also helps if you are not Ayrton Senna.

As for heat build up, I don't believe it to be any worse than any of the PD setups. In saying that I always HPC coat and wrap. I would do that with extractors on a blower anyway.. so to me its a mute point. I have found that most turbo "kits" have been designed by someone looking to make a buck and as such things like crappy oil feeds, turbo drains, poor heat sheilding etc just make them seem well amaturish. It takes more than a weekend of someone mucking around with a tig and some pipe to design a turbocharged installation.

As for power potential, well you can make more than you will ever need with both.

[vy2ttr]

I also believe it is personal preference. I like mine because under boost it drives like a stock ss. the wife drives it and has no dramas at all. Now with std ride height and stock wheels the cops dont even look twice. Yet if i stand on it at 150 it will light both tyres up. Brutal power, which some like some hate.
As far as the heat issue i have had none whatsoever, and i still drive mine hard on days well over 40 degrees. And on the dyno it makes same power run after run back to back. Where a lot of blown cars will suffer heat soak and get lower and lower.
And the end of the day get what makes ya happy

[Solone]

Power per pound of boost (intercooled): Turbo > Centrifugal > PD blower

Thermally efficient (no intercooler): Centrifugal > PD Blower > Turbo

Longevity of driveline: Centrifugal > Turbo > PD Blower

Ultimate Power potential: Turbo > Centrifugal > PD Blower

Ease of install: Centrifugal > PD Blower > Turbo

Cost of Setup @ 400rwkw: Centrifugal > PD Blower > Turbo

Fuel Efficiency: Centrifugal > Turbo > PD Blower

Quarter Mile Potential: Turbo > Centrifugal > PD Blower

Who says Centrifugal is the worst of these setups?

[macca_779]

I'd read it on several websites actually. Less parasitic loss from turbochargers and they act like mufflers as well to some degree.

That's all true. But for performance. Turbos will have more potential.

[IJ.]

Power per pound of boost (intercooled): Turbo > Centrifugal > PD blower

Thermally efficient (no intercooler): Centrifugal > PD Blower > Turbo

Longevity of driveline: Centrifugal > Turbo > PD Blower

Ultimate Power potential: Turbo > Centrifugal > PD Blower

Ease of install: Centrifugal > PD Blower > Turbo

Cost of Setup @ 400rwkw: Centrifugal > PD Blower > Turbo

Fuel Efficiency: Centrifugal > Turbo > PD Blower

Quarter Mile Potential: Turbo > Centrifugal > PD Blower

Who says Centrifugal is the worst of these setups?

You have the Lag of a Turbo and the Parasitic drag of a Blower....

Really depends on the end use of the vehicle and how you like the power to be delivered, I have Data Logs of my old 3.0L Turbo car turning the 285 rears at 160 Kmh in the dry on a well surfaced test track... I spent a lot of $$$ to make it drivable ending up with DBW TRAC in the end, without it I got my ass handed to me by an old lady in a Corolla ;)

[feistl]

Longevity of driveline: Centrifugal > Turbo > PD Blower

Ease of install: Centrifugal > PD Blower > Turbo


Not sure about the others, but i disagree with these two. Surely PD is easier on the driveline than a turbo?
And its much easier to install a PD blower than centrifugal as you dont have to worry about piping...

[XUV]

Blowers are cooler , tuffer :wave:

Mad Max had a blower, the blind guy in Running on empty had a blower, Dominic Toretto had a blower, o.k. bad example .

Say " it's blown " and the punters are ooooer, say " it's turbo's " and you think ricer, uncool, over use of bright green and orange .

[OMR346]

Blowers are cooler , tuffer :wave:

Mad Max had a blower, the blind guy in Running on empty had a blower, Dominic Toretto had a blower, o.k. bad example .

Say " it's blown " and the punters are ooooer, say " it's turbo's " and you think ricer, uncool, over use of bright green and orange .
Nuf said hahaha

[vessloveit]

Power per pound of boost (intercooled): Turbo > Centrifugal > PD blower

Thermally efficient (no intercooler): Centrifugal > PD Blower > Turbo

Longevity of driveline: Centrifugal > Turbo > PD Blower

Ultimate Power potential: Turbo > Centrifugal > PD Blower

Ease of install: Centrifugal > PD Blower > Turbo

Cost of Setup @ 400rwkw: Centrifugal > PD Blower > Turbo

Fuel Efficiency: Centrifugal > Turbo > PD Blower

Quarter Mile Potential: Turbo > Centrifugal > PD Blower

Who says Centrifugal is the worst of these setups?

Is this validated data or your opinion or some other persons opinion?

[vy2ttr]

Blowers are cooler , tuffer :wave:

Mad Max had a blower, the blind guy in Running on empty had a blower, Dominic Toretto had a blower, o.k. bad example .

Say " it's blown " and the punters are ooooer, say " it's turbo's " and you think ricer, uncool, over use of bright green and orange .


Haha, normally people with those sorts of blowers are the "look at me" sort of crowd. Id rather go under the radar, and watch them go "WTF" when i roll on past, lol

[MARRA]

Would it have anything to do with a TT Kit being heavily marketed a few years ago but now has disappeared so we don't really hear about them anymore...?

[OMR346]

I notice everyone is talking about TT kits, but no one has mentioned a big single. I tend to see more single turbo LSx's then TT set ups these days.

I wouldn't say no to either of set up myself, although i am currently looking at an intercooled centrifugal blower set up running 12psi

[IJ.]

Haha, normally people with those sorts of blowers are the "look at me" sort of crowd. Id rather go under the radar, and watch them go "WTF" when i roll on past, lol

The "WTF" Factor shouldn't be underestimated :D

[OMR346]

The "WTF" Factor shouldn't be underestimated :D

1947

Nuff said???

[IJ.]

Beautiful Car but hardly a Sleeper :D

(yep nuff for sure)

[Evman]

I doubt a supercharger, at least a roots type like the tvs would hold up for track racing for extended periods of time beyond a few hotlaps. I’d imagine it would get heatsoaked sooner or later as it does sit right on top of the engine and the heat would just keep rising to it.

You're right in some respects. Going off my experiences with track days, on a day somewhere in the 20s or lower the IATs actually remain surprisingly low, somewhere below 40degC. On a warmer day they definitely suffer from the heat, but once moving the temps will still stabilise around 50degC, which includes battling a continuously rising coolant temp. I've done a max of 10 laps straight at Barbagallo and the only heat issues I've had were coolant temps

[Evman]

The editing option is playing up for me. I would have liked to edit it to say...

"but once moving the temps will still stabilise somewhere below 50degC, which includes battling a continuously rising coolant temp"

[feistl]

I doubt a supercharger, at least a roots type like the tvs would hold up for track racing for extended periods of time beyond a few hotlaps. I’d imagine it would get heatsoaked sooner or later as it does sit right on top of the engine and the heat would just keep rising to it.

It will be interesting to see. Im hoping the cooling system keeps the entire engine cool, as well as HPC coating on the exhaust system. Plus the minimum speed doesnt drop below 80kp/h, so there is a fair amount of air moving through the engine bay. I also have monaro scoops which aid in ducting cold air onto the charger itself.

I guess the real question is how good is the water radiator for the intercooler? Will the high air speed aid in keeping the entire system cool?

These are the unknowns im facing.

If temps do rise to a bad level, i will experiment with water spray onto the intercooler radiator to bring temps down.

Also nothing personal at all (I honestly appreciate everyones opinions) but quite often what happens in the real world is different to what someone might logically think. Until you get out there and actually do it for real and record the data, its just educated guess work. I'm also talking from experience, where things i thought should work didnt, and vice versa.

The important thing is to share this information for everyones benefit.

Cheers

[duke5700]

All in the setup but a turbo would be more gentle than a PD.


Not sure about the others, but i disagree with these two. Surely PD is easier on the driveline than a turbo?
And its much easier to install a PD blower than centrifugal as you dont have to worry about piping...

[Evman]

It will be interesting to see. Im hoping the cooling system keeps the entire engine cool, as well as HPC coating on the exhaust system. Plus the minimum speed doesnt drop below 80kp/h, so there is a fair amount of air moving through the engine bay. I also have monaro scoops which aid in ducting cold air onto the charger itself.

I guess the real question is how good is the water radiator for the intercooler? Will the high air speed aid in keeping the entire system cool?

These are the unknowns im facing.

If temps do rise to a bad level, i will experiment with water spray onto the intercooler radiator to bring temps down.

Also nothing personal at all (I honestly appreciate everyones opinions) but quite often what happens in the real world is different to what someone might logically think. Until you get out there and actually do it for real and record the data, its just educated guess work. I'm also talking from experience, where things i thought should work didnt, and vice versa.

The important thing is to share this information for everyones benefit.

Cheers

I think you'll find the monaro scoops might work against the cooling. There is a lot of resistance when trying to push air through a radiator, let alone several, and any increase in air pressure behind it will only work against it. For a serious track car I'd be focusing more on getting air out of the engine bay over getting extra air in, especially if that air isn't going through radiators. Most reports I've heard from people who've tried the ally radiators such as PWR is that they still seem to get very high coolant temperatures, despite the apparent extra efficiency of the heat exchangers. Even speaking to someone recently who regularly competes in tarmac rallies said he didn't notice much difference between stock and PWR radiators, which he was really disappointed about.

On the lower end I'm running somewhere in the vicinity of 500rwkw with a stock VZ radiator system in my VY. It needs to be quite a cool day for me to not have a continuously climbing water temp. I have no idea if/when it would top out because I always go onto cool down mode when it hits 110degC, which is very much on the safe side.

[Jag530G]

I think you'll find the monaro scoops might work against the cooling. There is a lot of resistance when trying to push air through a radiator, let alone several, and any increase in air pressure behind it will only work against it. For a serious track car I'd be focusing more on getting air out of the engine bay over getting extra air in, especially if that air isn't going through radiators. Most reports I've heard from people who've tried the ally radiators such as PWR is that they still seem to get very high coolant temperatures, despite the apparent extra efficiency of the heat exchangers. Even speaking to someone recently who regularly competes in tarmac rallies said he didn't notice much difference between stock and PWR radiators, which he was really disappointed about.

On the lower end I'm running somewhere in the vicinity of 500rwkw with a stock VZ radiator system in my VY. It needs to be quite a cool day for me to not have a continuously climbing water temp. I have no idea if/when it would top out because I always go onto cool down mode when it hits 110degC, which is very much on the safe side.

Considering the mid point of the bonnet is a low pressure area, The VZ Monaro scoops aren't going to do to much facing forward, this area (perhaps back a little bit more) would be better for rear facing louvre to help extract air out of the engine bay behind the radiator. I'm not talking about the back of the bonnet because that area is a high pressure area.

Cheers, Matthew

[Evman]

Considering the mid point of the bonnet is a low pressure area, The VZ Monaro scoops aren't going to do to much facing forward, this area (perhaps back a little bit more) would be better for rear facing louvre to help extract air out of the engine bay behind the radiator. I'm not talking about the back of the bonnet because that area is a high pressure area.

Cheers, Matthew

Is it low enough to suck air out of the engine bay? Because that's what it needs

This forum has some major issues. I deleted that pic attached, but it still shows up. Awesome forum is awesome. None the less, it demonstrates that although the bonnet experiences lower pressure, not very far above it the airflow returns to higher pressure or at least neutral. I'd say the scoops would extend into the higher/neutral pressure zone

[IJ.]

I think you'll find the monaro scoops might work against the cooling. There is a lot of resistance when trying to push air through a radiator, let alone several, and any increase in air pressure behind it will only work against it. For a serious track car I'd be focusing more on getting air out of the engine bay over getting extra air in, especially if that air isn't going through radiators. Most reports I've heard from people who've tried the ally radiators such as PWR is that they still seem to get very high coolant temperatures, despite the apparent extra efficiency of the heat exchangers. Even speaking to someone recently who regularly competes in tarmac rallies said he didn't notice much difference between stock and PWR radiators, which he was really disappointed about.

On the lower end I'm running somewhere in the vicinity of 500rwkw with a stock VZ radiator system in my VY. It needs to be quite a cool day for me to not have a continuously climbing water temp. I have no idea if/when it would top out because I always go onto cool down mode when it hits 110degC, which is very much on the safe side.



Gave mine a bit of a pasting the other day in 30c heat, saw a 1c temp rise well after I backed off, PWR Rad.

[Jag530G]

Is it low enough to suck air out of the engine bay? Because that's what it needs

This forum has some major issues. I deleted that pic attached, but it still shows up. Awesome forum is awesome. None the less, it demonstrates that although the bonnet experiences lower pressure, not very far above it the airflow returns to higher pressure or at least neutral. I'd say the scoops would extend into the higher/neutral pressure zone

Yeah, looks a bit tight, you'd want the vent to draw air from behine the fan shroud but doesn't seem to be a lot of space for the vent before the air flow goes high pressure. Might just squeeze it in.

I wonder if the fans could be mounted in front of the radiator (don't know if possible) so that a vent could draw straight from the back of the radiator, that would give a bit more room along the bonnet to fit in the low pressure zone.

*edit* the vent i'm talking about would be more a lourve style, a bit like the bonnet vent thing on some Lance Evos.

[Solone]

Is this validated data or your opinion or some other persons opinion?

Do you not agree?

[IJ.]

Yeah, looks a bit tight, you'd want the vent to draw air from behine the fan shroud but doesn't seem to be a lot of space for the vent before the air flow goes high pressure. Might just squeeze it in.

I wonder if the fans could be mounted in front of the radiator (don't know if possible) so that a vent could draw straight from the back of the radiator, that would give a bit more room along the bonnet to fit in the low pressure zone.

*edit* the vent i'm talking about would be more a lourve style, a bit like the bonnet vent thing on some Lance Evos.

So very illegal ;)

Supra bonnet, like this??

1949

[Jag530G]

So very illegal ;)

For race tracks? (I'm writing only based on knowledge of aerodynamics/fluid dynamics, no particular knowledge of CAMS rules etc)

Cheers, Matthew

[IJ.]

Sorry meant for a road car ;)

[Woodchukka]

1947

Nuff said???

I am sure there is a better video I just can't find it.


http://www.youtube.com/watch?v=tyFFRVXrEQ0

[Jag530G]

So very illegal ;)

Supra bonnet, like this??

1949

Yep, that's just what I had in mind.

[white lie]

Power per pound of boost (intercooled): Turbo > Centrifugal > PD blower

Thermally efficient (no intercooler): Centrifugal > PD Blower > Turbo

Longevity of driveline: Centrifugal > Turbo > PD Blower

Ultimate Power potential: Turbo > Centrifugal > PD Blower

Ease of install: Centrifugal > PD Blower > Turbo

Cost of Setup @ 400rwkw: Centrifugal > PD Blower > Turbo

Fuel Efficiency: Centrifugal > Turbo > PD Blower

Quarter Mile Potential: Turbo > Centrifugal > PD Blower

Who says Centrifugal is the worst of these setups?



I disagree with a few on that list... what's your source or is it just your way of thinking?

As said a few times in this thread, the newer PD blowers will bypass at low throttle, Magnuson were claiming 1/3 of a hp loss when it's doing this at 60MPH. You'd be hard pressed to notice anything better than that from the "seat of the pants" dyno.

Low throttle (off boost), I didn't notice any change in fuel economy before and after fitting my blower. On boost fuel efficiency will depend entirely on the tune and how much boost is going in. If you're putting more air in, you generally need more fuel. You can't say a PD blower is less efficient just because its making more boost... it's also making more torque/power in that case!

[Evman]

SVE have this style which should work perfectly to draw extra air out

http://www.sve.net.au/prodimages/vz%20ssx%205.jpg.jpg

[feistl]

The other "mod" i had done was to raise the rear of the bonnet slightly by putting a couple of washers between the bonnet and hinge mounts, coupled with removing the rubber strip means there is a reasonably large gap where air can be vented. I tried to do some measurements but there was far too many variables. I can say though that the windscreen was always warm to the touch after driving at lowish speeds (So i assume hot air was escaping out and going over the window.

Again i wish i could test this thoroughly but its hard to get a controlled environment.

EDIT - I also run the VX Supercar front bumper when on the track, so it has a pretty good air dam effect and does get a lot more air through the radiators compared to the standard front bar. (Although it looks pretty tacky it one of the few times a "body kit" has been fitted for performance reasons alone).

[Jag530G]

SVE have this style which should work perfectly to draw extra air out

http://www.sve.net.au/prodimages/vz%20ssx%205.jpg.jpg

Yep, that looks perfect. @Feistl, you might want to look at a Monaro bonnet style version of the SVE style, I think you'll find the VZ Monaro bonnet to be a complete waste of time. I know people like the look of the VZ Monaro scoops. Holden developed them for the Pontiac GTO purely for styling reasons to tie in with the old GTO. In terms of engineering purpose the Monaro scoops are a complete wank really.

Cheers, Matthew

[IJ.]

The other "mod" i had done was to raise the rear of the bonnet slightly by putting a couple of washers between the bonnet and hinge mounts, coupled with removing the rubber strip means there is a reasonably large gap where air can be vented. I tried to do some measurements but there was far too many variables. I can say though that the windscreen was always warm to the touch after driving at lowish speeds (So i assume hot air was escaping out and going over the window.

Again i wish i could test this thoroughly but its hard to get a controlled environment.

Tried this on the Supra, it helped at low speeds but hurt at high speeds.

[Jag530G]

The other "mod" i had done was to raise the rear of the bonnet slightly by putting a couple of washers between the bonnet and hinge mounts, coupled with removing the rubber strip means there is a reasonably large gap where air can be vented. I tried to do some measurements but there was far too many variables. I can say though that the windscreen was always warm to the touch after driving at lowish speeds (So i assume hot air was escaping out and going over the window.

Again i wish i could test this thoroughly but its hard to get a controlled environment.

EDIT - I also run the VX Supercar front bumper when on the track, so it has a pretty good air dam effect and does get a lot more air through the radiators compared to the standard front bar. (Although it looks pretty tacky it one of the few times a "body kit" has been fitted for performance reasons alone).

The problem with raising the rear edge of the bonnet is that is in a high pressure area, it will actually draw air into the engine bay and stop air getting out. (thats why old Torana SLRs and VH Group 3s had rear facing scoop, it was the air intake for the engine, not as a means to exhaust hot air from the engine bay).

[Evman]

Can be seen here. The base of the windscreen gets as much pressure as the front of the car. I have no idea what speed this test was done at but I assume 60km/h or so. Also, I have no idea what pressure the areas are. Even the "high pressure" areas could be relatively low for all I know (but I'd assume not, especially at speed)

http://www.ls1.com.au/forum/attachment.php?attachmentid=1948&stc=1&d=1361441269

[Solone]

I disagree with a few on that list... what's your source or is it just your way of thinking?

As said a few times in this thread, the newer PD blowers will bypass at low throttle, Magnuson were claiming 1/3 of a hp loss when it's doing this at 60MPH. You'd be hard pressed to notice anything better than that from the "seat of the pants" dyno.

Low throttle (off boost), I didn't notice any change in fuel economy before and after fitting my blower. On boost fuel efficiency will depend entirely on the tune and how much boost is going in. If you're putting more air in, you generally need more fuel. You can't say a PD blower is less efficient just because its making more boost... it's also making more torque/power in that case!

Just because there is a valve dont mean the blower isnt making heat and costing power. The engine is still driving the blower at full tilt but the benfits are being blown out the back door. So the PD blower with a valve will have a heavy cost of power but not making any power. Also its just recirculating engine heat if not on boost. If its a top mount blower it has to be heatsoaked as the heat from the engine rises straight into it. If its a twin screw blower then its always generating heat whether its valve is open or not as its internally compressing air. The eaton type by design generates so much heat when its on boost and when not on boost it recirculating engine heat.

The centifugal by design isnt costing much power as its not spinning hard down low and it free spins. Doesnt exchange heat with the motor, only up in rpm is it costing power to make power. The PD system is heavily taxing the motor of power but for most of the driving its being vented out the back door?

[IJ.]

Just because there is a valve dont mean the blower isnt making heat and costing power. The engine is still driving the blower at full tilt but the benfits are being blown out the back door. So the PD blower with a valve will have a heavy cost of power but not making any power. Also its just recirculating engine heat if not on boost. If its a top mount blower it has to be heatsoaked as the heat from the engine rises straight into it. If its a twin screw blower then its always generating heat whether its valve is open or not as its internally compressing air. The eaton type by design generates so much heat when its on boost and when not on boost it recirculating engine heat.

The centifugal by design isnt costing much power as its not spinning hard down low and it free spins. Doesnt exchange heat with the motor, only up in rpm is it costing power to make power. The PD system is heavily taxing the motor of power but for most of the driving its being vented out the back door?
Are you trying to tell us with the gear ratio needed to spin up a Centri that at low engine speeds there's no load/parasitic drag?

I don't know how accurate the Magnusson claim is but 1/3 of a HP at 100 Kmh is nothing.

[Solone]

Are you trying to tell us with the gear ratio needed to spin up a Centri that at low engine speeds there's no load/parasitic drag?

I don't know how accurate the Magnusson claim is but 1/3 of a HP at 100 Kmh is nothing.

Of course there is still some loss but Id argue much less than a PD blower. Not only less Parasitic loss but much lower IATs as well.

There was a test done between a roots type supercharger (TVS is a roots type) and Centrifugal....

http://www.lextreme.com/icvsnic.htm

[white lie]

I don't really see what the big issue is with 'costing power' if you're just cruising down the highway... It may effect the fuel efficiency but power wise, it shouldn't be an issue as you're not using much.

Yes, it will generate heat but this doesn't necessarily effect the intake temps when the car is moving. If its a dyno queen, then you may have a valid case but there are still ways around that.

[IJ.]

At 100 kmh/ roughly 2000rpm in most cars your Centri is spinning at 14800 Rpm, can't see the load would be so much lower than a PD in bypass...

By all means buy one and let us know how it works for you, keep in mind there's a LOT of sales hype attached to these things.

[Solone]

At 100 kmh/ roughly 2000rpm in most cars your Centri is spinning at 14800 Rpm, can't see the load would be so much lower than a PD in bypass...

By all means buy one and let us know how it works for you, keep in mind there's a LOT of sales hype attached to these things.

The centris shortcoming is its lack of boost down low but its offset by the less "cost of power" of running it down low as well. Its just a fact that Centris dont cost as much power as PD units. Thats one of the reasons why per pound of boost they are superior. (and the less heat)

[Solone]

read this!!

http://www.lextreme.com/icvsnic.htm

[white lie]

Of course there is still some loss but Id argue much less than a PD blower. Not only less Parasitic loss but much lower IATs as well.

There was a test done between a roots type supercharger (TVS is a roots type) and Centrifugal....

http://www.lextreme.com/icvsnic.htm

I don't quite see how this link is valid to your argument.
It's essentially comparing a non intercooled, thermally inefficient Roots blower to an intercooled centrifugal.
Firstly, the TVS are 76% thermally efficient, which is leaps and bounds ahead of what they're using in this test. And secondly, they are of course intercooled.

[IJ.]

read this!!

http://www.lextreme.com/icvsnic.htm

All from the Corky Bell book that's 20 years out of date.....

[Solone]

The BOSS 335 guys on the Ford Forums whinge about their cars being heatsoaked. They are also factory engineered setups!!

Really boils down to what you want from your car. Each setup has their pro and cons.

[IJ.]

The BOSS 335 guys on the Ford Forums whinge about their cars being heatsoaked. They are also factory engineered setups!!

Really boils down to what you want from your car. Each setup has their pro and cons.

Non Intercooled....

What I "want" and have from a Blower is instant boost, 1600rpm it's making usable boost, don't know about you but my cars are drivers and it's nice having the response "right now" when I want it, if you were building aq 1/4 mile car or even a Circuit car that you can keep in it's powerband fine but a road car the PD wins hands down.

[XUV]

The other "mod" i had done was to raise the rear of the bonnet slightly by putting a couple of washers between the bonnet and hinge mounts, coupled with removing the rubber strip means there is a reasonably large gap where air can be vented. I tried to do some measurements but there was far too many variables. I can say though that the windscreen was always warm to the touch after driving at lowish speeds (So i assume hot air was escaping out and going over the window.

Again i wish i could test this thoroughly but its hard to get a controlled environment.
.

we use to do that with NA big blocks , Have the WB's bonnet sitting up an inch near the windscreen .

[Jag530G]

Tried this on the Supra, it helped at low speeds but hurt at high speeds.


Can be seen here. The base of the windscreen gets as much pressure as the front of the car. I have no idea what speed this test was done at but I assume 60km/h or so. Also, I have no idea what pressure the areas are. Even the "high pressure" areas could be relatively low for all I know (but I'd assume not, especially at speed)

http://www.ls1.com.au/forum/attachment.php?attachmentid=1948&stc=1&d=1361441269

I think what is happening to IJ's Supra was the issue of pressure difference between under the bonnet and at the base of the windscreen, at low speeds the air pressure in the engine bay was greater than at the base of the windscreen, hence raising the rear edge of the bonnet worked at low speeds. But as the speed got much higher the pressure difference went the other way, the base of the windscreen was higher pressure than the engine bay, hence air wasn't sucked out of the engine bay and there wasn't any cooling benefit.

Cheers, Matthew

[IJ.]

I think what made it worse at high speed Matt was the High pressure at the base of the screen would impede the incoming air through the radiator, those cars were marginal for cooling at the best of times due to the tiny frontal area, if you left the undertray off you saw a 5c rise as the air took a shortcut under the radiator as the path of least resistance.

[Evman]

The BOSS 335 guys on the Ford Forums whinge about their cars being heatsoaked. They are also factory engineered setups!!

Really boils down to what you want from your car. Each setup has their pro and cons.

Factory engineered without any intercooling.

Heat is an issue in PD blowers. The intercoolers are often so small it's very difficult to get a large amount of heat out of the air. The main advantage that centri blowers have is they can run an air-air intercooler which is much more efficient. On a hot day with city driving my IAT will hover around 60degC (I have an M1900). My car is predominantly a daily driver. That means I'm not driving around the streets at 5000rpm and 9-10psi ready to go. I don't drive my car below 1500rpm, but in normal circumstances it wont see 3000rpm either. That's quite a short band to drive a car in, but when you're making a solid 6.5-7psi at 2500rpm you don't really need to go beyond 3000rpm because you're already making plenty of power (roughly 200rwhp at 2500rpm in my case). The other thing that needs pointing out is that the lower the rpm, the lower the effect of hot air. My mechanic gave me a dyno graph showing a cool power run vs a hot power run. Cool it made 513rwhp at peak, hot it made 490. At 3000rpm though the difference was 10rwhp (250 hot vs 260 cool). I'd never be able to pick 10hp.

[Jag530G]

I think what made it worse at high speed Matt was the High pressure at the base of the screen would impede the incoming air through the radiator, those cars were marginal for cooling at the best of times due to the tiny frontal area, if you left the undertray off you saw a 5c rise as the air took a shortcut under the radiator as the path of least resistance.

And the extra air going underneath would have caused more front end lift, so an undertray/splitter would serve two benefits, less front end lift and better cooling. Feistl's previous post he mentions he uses a V8 supercar front, so that should serve as a splitter. I'd say with Feistl's race-car, the air going in the front is all fine, it is getting it out that could be an issue and the VZ Monaro bonnet or raising the rear edge won't really help.....

Cheers, Matthew

[Jag530G]

This all reminds me of when Jaguar bought out the XKR supercharged V8 coupe. COmpared with the nn-supercharged XK8, the XKR had two rear facing louvre bonnet vents in the front corners of the bonnet to help with cooling. They had the added effect of reducing lift at the front so Jaguar had to fit a rear lip spoiler to balance out the lift over the front and rear of the car.

Goes to show that cooling and aerodynamics of a car really do go hand in hand and luckily tend to be mutually beneficial. If you get the airflow through the engine bay right it tends to reduce lift at the same time as cooling the car properly.

Cheers, Matthew

[IJ.]

Ideal situation would be a pair of large vents in the rear corners of the engine bay exiting out through louvres in the guards....

Not sure how practical this would be though.

[Jag530G]

Ideal situation would be a pair of large vents in the rear corners of the engine bay exiting out through louvres in the guards....

Not sure how practical this would be though.

Yes, could also pump the front guards out so that there is a nice gap between the rear edge of the guard and the front edge of the door and have the engine bay airflow vent out through this gap. Would look a bit like the Dodge Viper. IIRC there was a heavily modified V2/VZ Monaro in Street Machine which had the front guards were pumped out (had the bonus of fiting wider rubber).

Something else I remember is the Monaro 427, it had two vent holes in the bonnet in the front corners and a small splitter on an otherwise standard looking V2 Monaro front bar (not the HSV bar). The Monaro that was given to Peter Hanenburger on his retirement had the 427 splitter so he could hoon down the autobahns back home.

Cheers, Matthew

[Solone]

Watch This... in particular Look at the effect of heatsoak..

http://www.youtube.com/watch?v=qowkRc6qcZ8

[Solone]

Factory engineered without any intercooling.

Heat is an issue in PD blowers. The intercoolers are often so small it's very difficult to get a large amount of heat out of the air. The main advantage that centri blowers have is they can run an air-air intercooler which is much more efficient. On a hot day with city driving my IAT will hover around 60degC (I have an M1900). My car is predominantly a daily driver. That means I'm not driving around the streets at 5000rpm and 9-10psi ready to go. I don't drive my car below 1500rpm, but in normal circumstances it wont see 3000rpm either. That's quite a short band to drive a car in, but when you're making a solid 6.5-7psi at 2500rpm you don't really need to go beyond 3000rpm because you're already making plenty of power (roughly 200rwhp at 2500rpm in my case). The other thing that needs pointing out is that the lower the rpm, the lower the effect of hot air. My mechanic gave me a dyno graph showing a cool power run vs a hot power run. Cool it made 513rwhp at peak, hot it made 490. At 3000rpm though the difference was 10rwhp (250 hot vs 260 cool). I'd never be able to pick 10hp.

But what about if the Supercharger didnt generate this heat to start with? Your comparing hot air against hotter air. At same boost a centri with its cooler intake temps may have made 550rwhp.

[Evman]

Something else I remember is the Monaro 427, it had two vent holes in the bonnet in the front corners

They were intakes for the engine if memory serves me correctly

[Tre-Cool]

years ago, we dynoed my then vortech blown 5.7 vy ute. just running the belt on the blower cost over 40rwhp on a dyno run.

i.e ran the car with no boost without blower belt on and then with.

if the belt is still spinning the ****ing pulley it's taking power.

[steve_t]

years ago, we dynoed my then vortech blown 5.7 vy ute. just running the belt on the blower cost over 40rwhp on a dyno run.

i.e ran the car with no boost without blower belt on and then with.

if the belt is still spinning the ****ing pulley it's taking power.

40rwhp to run the belt?!! :eek:

[IJ.]

years ago, we dynoed my then vortech blown 5.7 vy ute. just running the belt on the blower cost over 40rwhp on a dyno run.

i.e ran the car with no boost without blower belt on and then with.

if the belt is still spinning the ****ing pulley it's taking power.

This was the point I was trying to make earlier, NOTHING is "Free Spinning" the overall ratio is something like 7.4:1 so it's going to take power to turn, as I posted earlier I'd be impressed by Magnusson's claim of 1/3hp/100 Kmh as an old school 6/71 took about 100hp to turn at 5000 rpm!

[JezzaB]

This was the point I was trying to make earlier, NOTHING is "Free Spinning" the overall ratio is something like 7.4:1 so it's going to take power to turn, as I posted earlier I'd be impressed by Magnusson's claim of 1/3hp/100 Kmh as an old school 6/71 took about 100hp to turn at 5000 rpm!


1/3 of a hp?? What's it disengage the gears from the transmission and just run the pulley on the bearing??

[feistl]

Just because there is a valve dont mean the blower isnt making heat and costing power. The engine is still driving the blower at full tilt but the benfits are being blown out the back door. So the PD blower with a valve will have a heavy cost of power but not making any power. Also its just recirculating engine heat if not on boost. If its a top mount blower it has to be heatsoaked as the heat from the engine rises straight into it. If its a twin screw blower then its always generating heat whether its valve is open or not as its internally compressing air. The eaton type by design generates so much heat when its on boost and when not on boost it recirculating engine heat.

The centifugal by design isnt costing much power as its not spinning hard down low and it free spins. Doesnt exchange heat with the motor, only up in rpm is it costing power to make power. The PD system is heavily taxing the motor of power but for most of the driving its being vented out the back door?

Correct me if im wrong here, but the eaton twin screw pd charger (EG HTV1900 or HTV2300) only has partial compression between the lobes, the compression actually occurs in the manifold itself. So when the value is open, the charger is only making a small amount of boost and only using a small amount of power to be driven. You seem to be implying that its using FULL power while making no boost pressure? If thats what your saying, then your technically incorrect.

There is some air which is recirculated and yes it will suffer some heat soak, but the amount is still relatively low. In that video with the heat soak comparison they shown a 22hp drop (On 450hp) when heat soaked... Thats a ~5% drop in power when heat soaked....

Considering most HTV2300 setups are making 400rwkw or more, dropping a few hp here or there doesnt really seem that big a deal? Or maybe thats just me...

[IJ.]

1/3 of a hp?? What's it disengage the gears from the transmission and just run the pulley on the bearing??
It's powered by Unicorns ;)


Correct me if im wrong here, but the eaton twin screw pd charger (EG HTV1900 or HTV2300) only has partial compression between the lobes, the compression actually occurs in the manifold itself. So when the value is open, the charger is only making a small amount of boost and only using a small amount of power to be driven. You seem to be implying that its using FULL power while making no boost pressure? If thats what your saying, then your technically incorrect.

There is some air which is recirculated and yes it will suffer some heat soak, but the amount is still relatively low. In that video with the heat soak comparison they shown a 22hp drop (On 450hp) when heat soaked... Thats a ~5% drop in power when heat soaked....

Considering most HTV2300 setups are making 400rwkw or more, dropping a few hp here or there doesnt really seem that big a deal? Or maybe thats just me...

Agreed even the best calibrated Butt Dyno would have trouble picking that drop in the real world...

Also looked like they were rolling into the throttle so the Dyno Graph Traces would be comparable....

[1HDT 05]

I think most of the discussion is out of context. On the street both applications are great I wouldn't say no to either if they rolled up on my door step. At the drags the same thing, they are even in their negatives and positives. At gymkhana they are both good. Here's the controversial part, they both suck at a true racetrack, because both of them fail with heat issues. Before you say nay etc etc I have been on GTR forums, 350 and 370z forums and M3 forums and all the forced induction setups have heat issues at the racetrack. Unless of course they are dedicated racecars. You want to track your car? Then steer clear of forced induction, period. If you want to be a dyno queen or straightline (boring) drag specialist, then either will suit. For on road my turbo under 3k is a dream to drive, over 3k all hell breaks loose. And for street thats the way I reckon you want it, pussy at low revs, monster after.

[vessloveit]

Do you not agree?

Not agreeing or disagreeing I just like to know if information given on any internet site is good or not, as we all know there is a lot of misinformation on the net.

[Solone]

Not agreeing or disagreeing I just like to know if information given on any internet site is good or not, as we all know there is a lot of misinformation on the net.


Research those points. . Pretty sure you will come to same conclusions