Plastic manifolds on ls turbo

[8lambo]

Hi, can anyone tell me how much boost the plastic ls manifolds can handle, or if anyone has had any boosting problems because of the plastic not being strong enough for their turbo set up?
Thanks
Nik

[whitels1ss]

One big problem is if the engine ever backfires.:yup:

[8lambo]

One big problem is if the engine ever backfires.:yup:

Yeah that wouldn't be cool, surely they can handle a certain amount of boost, how much is the question? I wonder if someone has found this out the hard way?

[Toddler78]

It would be tune dependant a well tuned set up combo will allow you to run more boost then a poorly tuned car. I have personally seen 20psi on a completely stock (bar valve springs) without any issues

[Toddler78]

How much boost are you planning to run?

[8lambo]

How much boost are you planning to run?

I'm thinking initially to run around 15-20. But it's a gt45 so it's not going to be hard to turn it up, and I know that eventually I'm probably going to want to. I need to buy a manifold and don't want to buy it twice. The thing I don't like about the aluminium banana style is the heat soak. The thing I'm worried about the composite/ plastic is the strength. Thanks for your input. Cheers

[boggers007]

I'm thinking initially to run around 15-20. But it's a gt45 so it's not going to be hard to turn it up, and I know that eventually I'm probably going to want to. I need to buy a manifold and don't want to buy it twice. The thing I don't like about the aluminium banana style is the heat soak. The thing I'm worried about the composite/ plastic is the strength. Thanks for your input. Cheers

Years ago either on here or another forum there was the 440LSX Blown ute build was twin turbo etc and I remember that splitting a Fast Manifold on the dyno. Not sure how much boost it was running etc the build page may still be up here as it was done by Sonny when he was at marano's but I know they went to the aluminium intake and ran the car to what they deemed safe power level at 1200hp in the end or there abouts.

[8lambo]

Years ago either on here or another forum there was the 440LSX Blown ute build was twin turbo etc and I remember that splitting a Fast Manifold on the dyno. Not sure how much boost it was running etc the build page may still be up here as it was done by Sonny when he was at marano's but I know they went to the aluminium intake and ran the car to what they deemed safe power level at 1200hp in the end or there abouts.

Yeah I think the plastic manifolds would have a limit of sorts. Probably around the 1000hp and up mark , And upwards of 20+ pounds boost. For reliability sake I'm leaning towards the aluminium even tho it's not my preference. Cheers

[duke5700]

CPC Plenums have a new CNC'd one that would be worth checking out.

Plenty of welded ones on the marked as well.

[8lambo]

CPC Plenums have a new CNC'd one that would be worth checking out.

Plenty of welded ones on the marked as well.

I have been looking at the raised runner style, do you know if there has been any good or negative feedback on those ? I have the room for one and they look like their not that expensive anymore like the used to be when they first hit the market. Anyone got one that can shed some light?

[SASLS1]

Found this, it states the OEM composite manifold is tested to 80psi...

http://www.managed-programs.com/SiteAssets/news-press/Popular%20Hot%20Rodding%20-%207-29-03%20F.A.S.T.%20Science%20LS1%20Intake%20Manifold. pdf

[duke5700]

I take it you are talking about the Edelbrock/Holley one?

I know a few people with them and no complaints. Never seen any EGT data or the like with them or back to back boosted comparisons.

[8lambo]

O
Found this, it states the OEM composite manifold is tested to 80psi...

http://www.managed-programs.com/SiteAssets/news-press/Popular%20Hot%20Rodding%20-%207-29-03%20F.A.S.T.%20Science%20LS1%20Intake%20Manifold. pdf
Now that's a good read, definitely answers my original question. 80psi is a massive amount. Now I'm starting to feel better about the composite. Thanks heaps. And thanks to everyone who had a say. Cheers

[johnv]

The factory composite manifolds hold up well to boost, the fast have been known to split under moderate to high boost.
I have gone with the Holley Hi Ram for my latest build, but height can be an issue with them.

[8lambo]

The factory composite manifolds hold up well to boost, the fast have been known to split under moderate to high boost.
I have gone with the Holley Hi Ram for my latest build, but height can be an issue with them.

Yeah I have heard the fast manifolds are a bit over rated apart from their good looks. From what I have researched the oem manifolds a great and not ridiculously different to the after market fast. I guess millions of research dollars would have gone into the oem factory manifolds, that's why I think I'm going to stick to one. Thanks

[whitels1ss]

Yeah I have heard the fast manifolds are a bit over rated apart from their good looks. From what I have researched the oem manifolds a great and not ridiculously different to the after market fast. I guess millions of research dollars would have gone into the oem factory manifolds, that's why I think I'm going to stick to one. Thanks

I just don't think that they are designed for big boosted turbo applications but they work very well on highly modified n/a.

[jca]

Factory is a lot stronger then fast you will break other things before the manifold ive ran 22psi no problem

[The_Plague]

8lambo

I had a similar thread mate, the result is probably confusion:

http://www.ls1.com.au/forum/showthread.php?169338-Manifold-and-Throttle-Body-Question

So it has happened, a few years ago now.
http://www.ls1.com.au/forum/showthread.php?137520-Lsx-102-wilson-manifold-split-under-boost-!!!&highlight=fast+manifold+split+boost

I rang the US and had a chat to them and they state they have now tested up to 66psi through them to make sure, but you obviously need to take that with a grain of salt - they wouldn't be stating over the phone "oh **** no, they can't cope with jack shit, steer clear"

If you want to wait a bit I will get back to you with a result, I am getting hold of a FAST 92mm with a matching throttle body and we are going to shoot for about 650+rwhp with two turbos through it at 11psi - so to be fair obviously a lot less boost than the 1200hp monster in the other thread.
If it doesn't cope - in spectacular fashion as above - I will get back to you lol.