Hey guys I tried searching for this info but couldn't find any real info.

Ok so I am building a single turbo setup for my C5. Here is the info:

99 C5 6 speed
07 LS2 block with ARP rod bolts and ARP head studs
LS9 Gaskets
Stock 317's with valvetrain
228/228 .588/.588 114lsa turbo cam
LS2 intake mani and TB
2 Bosch 044 pumps
FIC 1000cc injectors
e85

I will be using the PT7675 CEA billet wheel turbo with all the right supporting parts.

My question is:
I have noticed that this turbo makes some awesome power and insane torque(dont need 900+tq) with .96 housing on it however everybody's dyno graph falls off up top. Power seems to fade around 6000rpm's or sooner. Being a 6 speed I still want a quick spool but dont want power falling off. At the same time I dont want it to spool too fast and hurt my traction. Would I benefit from going with one of the bigger housings? Like the 1.15/1.28/1.32? I know they are split housings tho. What are the pro's and con's of a split housing on an open t4 manifold?

We have even considered porting the .96 or even one of the split housings. Has anybody ever done this?

Sorry if this is a newb question but I just wanted to get the RIGHT setup the first time. I'm looking to make 750-800 usable WHP.

Thanks!

 

Hey man I got your pm but figure ill post here as I'd like to hear feedback as well. I went with a .96 AR and am not sure if a bigger housing would benefit my 346ci since its got a 75mm turbine wheel. I figure that would be the choke point but I'd like to hear other people experience.

There were a few people that were looking into larger AR housings for the tc78 but since that thing had a dinky 68mm turbine wheel I don't think it would have helped at all. The 75 on our turbos are a bit bigger at least.

 

Btw I maxed out my 95lb injectors on e85 and wasn't pushing the turbo so you may want to consider some bigger injectors. I may go with 1600 or 2000 cc although the later is over kill for my setup.

However you should be able to make your power goals on a 6speed with those injectors on e85. They will be near their max though I'd think.

 

I dont think the 75mm turbine wheel will be the choking point. Eventually yes, but I dont think so on our setups.

I am still stock block right now so 800whp is as high as I would want to go. Next year I will forge it and go with the 1600's.

 

Bump, lets get some info going here fellas!

 

I had a TC 78 on a 383 with a .96 and went to a 1.32 ar, used to fall over around 5500 rpm with the .96, but would carry it to the limiter , 6700rpm with the 1.32 ar and spool just as quick.

 

How much more power did you make after going to the 1.32? Can you post up your dyno graph or PM it to me? Was the 1.32 a split housing?

 

John, was it a T78 or a TC78? I thought the main restriction on those tc78's was always the 68mm turbine wheel. Maybe I've been under the wrong understanding

 

yeah allowing that big of an AR on the 68 wheel will help you

yeah the 68 kills the v8's thats like running a PTE 6766. sure the compressor moves more, but the exhuast wheel just fills up.

 

you will be happy with the .96 ar housing. Especially with your power goals. Having a 6 speed car you would rather have the smaller ar side. If you ever switch to an automatic you should think about getting a bigger exhaust housing though.

 

You need about a 1.15~1.25 in a divided to equal a open .96 housing imo. Here is my S480/1.25 housing stock, mild ported/blend, and full ported and cut down divider.

 

So If I went with a 1.28 housing and ported it and cut down the divider what do you think spool time would change to? I am just wanting to make power to redline. Im sure an LS2 with a turbo cam and a billet wheel 76mm is going to spool quick regardless, right?

 

Does the 1.28 come with a bigger turbine ? The notching and port work help but you need a big turbine if you want to carry the power high. I've found the 75mm turbines are going to plane off around 6k on 6.0L pretty much with any ex housing. The pt 76/75 might level off around 6k but it should hang in until 6500 or so before dropping much. Prob won't feel it fall off until 68-7k in seat of the pants. If you have room a S476/92/1.25 T4 ported a little would be about perfect.

 

I have always used Precision turbos with great results. And yes room is VERY tight in the engine bay of a C5 lol

Willmz: Can you post up your dyno graph?

 

I'm waiting on Nick to get it to me from straightline. Once I get it I'll post it up

 

Willizm: Sounds good man. Cant wait to see it.


So what do you guys think about stepping up to the Ball Bearing option?

 

Bump, I know we have some knowledgeable guys that can chime in!

 

haha how long does it take to email a dyno graph?

 

I think you should be worried about your transaxle lasting at your desired power levels

That whooshing sound will be the $ flying out of your wallet trying to keep the trans/rear diff together! '08+ Z06 TR6060 trans/diff is in your near future.... or lots of T56 rebuilds/repairs.

 

haha I already have a DTE Diff and brace, 300m axles, as well as a slightly beefed up MN12 t56 and LG Solid TT bushings. However, I don't plan on hurting it. I will be switching to a TR6060 and C6Z diff as soon as I can sell my drivetrain and save a little cash. Until then I will be very nice to my stuff.

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