Private Practice Meeting at Calder 12-09-03

[GMVPSS]

I am taking the VP out for its first squirt next week at the above meeting. This isn’t a night street meeting, it is a day meeting 10am~4pm for ‘race cars’ however after saying that I am not sure if it is open to ‘regular’ cars who want to get some unlimited runs in. (Contact Calder I guess??)

I have made a few changes to the car starting with removal of the factory seat and replacing it with a fibreglass Velo seat. This has saved quite a few kg as the std seat is heaps heavier than the 7kg glass seat.

2nd mod is the fitment of a Stefs Vacuum pump. This pump sucks all the air out of the crankcase that in theory creates a vacuum so that there is no air resistance in the crankcase and helps to improve ring seal and there fore compression and reduce blow-bye. If you imagine the piston going up and down at 6500rpm, the air underneath the piston is forced up and down along with the piston. On the down strok the air is rushing down the bore through the crankcase looking for a piston that is on the up stroke to follow. When there is a vacuum in the crankcase there is no air resistance. The pump is run at approx 50% crank speed (55% in my case due to the relatively low engine rpm) and will make about 15” of vacuum (approx 7 negative psi.)

The catch can is mounted up under the front LH wheel arch as there was no room in the engine bay or between the bumper and radiator support panel. Access to the drain **** is still quite easy. In the USA it is a very common fitment to aspirated engines and on a 400Hp motor they commonly make an easy 20Hp without touching anything else. A simple (but expensive) mod.

I have probably added 10kg back on with the pump, bracket and toothed pulleys that I manufactured, but it is still lighter than with the std seat and I will hopefully be making around 20Hp more.

Email me for photos, Darren@hookplastics.com.au and I will forward them to you, or alternatively maybe Strife might post the pics that I sent him here for you to see?!?!

Predictions of improvement?? I have run 10.609 @ 125.80 with a 1.43 60’. If I can drop and honest 0.2sec and pick up 1 or 2mph I will be happy.

Firing it up this weekend to check everything over, change the engine oil and prepare it for the 12th. Fingers Crossed that the track dries out from all the rain and it is prepared properly so we can all get some traction!!

Cheers,

Darren
Darren@hookplastics.com.au

[strife]

Ill post up the pics tonight

[ProVK]

Darren, I was under the impression the gains from a vacuum pump came mostly from a much improved ring seal when running a slight vacuum in the sump ?

[MR-LS1]

may come down for a look Daz if i get the ute back by then...

:thumbsup:

Tony.

[GMVPSS]

Originally posted by ProVK
Darren, I was under the impression the gains from a vacuum pump came mostly from a much improved ring seal when running a slight vacuum in the sump ?

Matt,

From what i have read from the USA and the Moroso Vacuum Pump instructions that the biggest improvement will come from using low drag or low tension rings and then allowing the vacuum in the crankcase to improve the ring seal. They also make comment on internal air resistance for the air travelling through the crankcase. I guess it is also why a lot of engine builders 'Knife Edge' their cranks, so it isnt resisted by the air and oil that is floating around down there. In theory that wouldnt be required if there is a vacuum in there!?!?!?

From the other stuff i have read that the only down side is that you can actually suck the oil from the bearings, so you have to keep an eye on the actual amount of vacuum and limit it to 15". The oil will also find it harder to make its way back down to the sump as the air is being sucked through the oil return holes and clearance holes around the pushrods.

I guess we'll see if it dpes make any real world improvements on the big 383ci motor that doesnt have low tension racing rings in it next week!!

In the USA they advertise these kits for Chev and Fraud as a bolt on 20Hp for around $750USD. Obviously i had to fabricate everything due to it being for a Holden and it being a 2nd hand pump.

Darren

[HRTSEN]

Hi Darren

Be careful adding the psi comment above....rice burners will go around saying GMVPSS has boost!

Excellent idea......good luck and I hope it gives you a positive outcome. May I ask about your motor that it is in the vehicle will you take the motor out for checking results on an engine dyno or just use the track for results?

regards,

Richard
CLUBVX

[GMVPSS]

Hey Richard,

Yeah it is negative PSI!! If the rice boys want to compare with Negative PSI, bring it on!!

The engine was set up on the engine dyno right from the start. It has never been on a chassis dyno or out on the engine dyno since. I wont be pulling it to check the HP with the pump now, but when i slide a solid cam in i will have it out and on the engine dyno to tune it properly again.

With the converter (5500rpm) it makes it useless to tune on a chassis dyno and a lot of dyno operators wont have anything to do with a car with that size converter.

Just fired the engine up and i am actully pulling too much vacuum. Just about to go to the Stefs and Moroso pages to look for a vacuum bleed off valve.

Darren

[strife]

http://www.hsvgto.com/Vac_Pump_Top.jpg

http://www.hsvgto.com/Vac_Pump_Top2.jpg

http://www.hsvgto.com/Vac_Pump_Crank.jpg

http://www.hsvgto.com/Vac_Pump_Alt.jpg

[strife]

http://www.hsvgto.com/VELO_Esprit_Seat.jpg

http://www.hsvgto.com/VELO_Esprit_Seat1.jpg

http://www.hsvgto.com/VELO_Esprit_Seat2.jpg

http://www.hsvgto.com/VELO_Esprit_Mounting.jpg

[mavss]

Sweet pics.

Are the levers in the last pic used to help slow you down or something?

[Ghosn]

Good Luck with the times... Car still looks awesome

[GMVPSS]

Yeah i flip the bootlid and open the fuel flap to slow me down!!

Thanks for the pics Strife!!!!
Thanks Ghosn

[Statesman355]

Hey Darren,
Good luck next weekend......
Hope to catch you up here
again next year.
James

[GMVPSS]

Well i am home after the big day out at calder and am happy with the improvements. At least i have to go and update my signature again!! ;)

After a couple of wasted runs due to the slippery start line i managed to put down a new PB time of 10.546@126.86 late this afternoon. I backed it up on the run before with a 10.579@126.54. The car hooked up well both times with a 1.432 and a 1.461 60' time.

Now i have a few more things in mind to go a little faster and i'll get into those over the new few weeks before i head out again!!

All this in preparation of the opening of the new Sydney track!!

Cheers,

Darren

[strife]

well done

nearly on the money!

[HRTSEN]

Hi Darren

Congrats on the improvement.

regards,

Richard
CLUBVX

[GMVPSS]

Thanks for the instant update on the quicklist Strife, but shouldnt the time be the 10.546@126.86 pass??? Backed up by the 10.579??

Just wondering!!

Cheers,
Darren

[strife]

From the engine rooom

http://www.engineroom.cjb.net/

http://www.angelfire.com/falcon/calderpark/DSC06672.gif

http://www.angelfire.com/falcon/calderpark/DSC06694.gif

http://www.angelfire.com/falcon/calderpark/DSC06642.gif

[HRTSEN]

WOW

Now that would make my day turning up to Frankston Dandy Road with that car on a Thursday night!!!

By the way Darren I have a factory within a few hundred metres to the Frankston Dandy Road drags to hide the car from the law in case you want to?....hehehehe

regards,

Richard
CLUBVX

[GMVPSS]

Hey Richard, we'll have to do something with the open pipes for that!! But i agree it would be awesome to pull the wheels up across the lights in Dandenong!! :)

Strife, thanks for posting the pics. AWESOME!!

[Brett SS]

Great work Darren, glad to see that you keep improving on your times. :thumbsup:

You still haven't replaced your front struts with shorter ones yet? Would look even more impressive with your front wheels 4" off the ground. :bow:

Still looking forward to having that grudge match with you that we missed out on last time, just make sure you give me a good second or so head start. ;)