Thirian24

Ok I'm building a 408/L92 and plan on running a Garrett 88mm turbo. I'll list my build info tell me what you think.

Lq4- .030 over
Ls7 crank w/ ARP main studs
Wiesco 2618 Forged pistons
K1 H beam rods w/ ARP 2000 bolts
Ported and polished L92s
MLS head gaskets with ARP head studs
Ls7 Lifters
Comp ultra gold rockers
9.4:1 compression ratio
Custom grind cam - 239/239 .624/.624 114+2 LSA
Edelbrock L92 intake w/ 90 degree elbow
Truck manifolds

I haven't decided on intercooler and injector size
yet. But assuming that I get enough fuel and a good
tune what kind of HP numbers should I expect at
15 psi?

This is going in a 90 notchback with a Glide if that will help with a rwhp estimate.

Thanks, Dustin

1_Bad_82ttCamaro

I would estimate between 8-900 hp depending on all the numbers but thats a ruff estimate.

yessir

iTrader: (5)

pump gas....bout 700-775 thru the glide

Thirian24

Hmm, I was hoping for close too 900 rwhp. Is the Glide gonna rob more power then a TH400? What do I need to do to reach this goal?

Thanks, Dustin

dudeman

iTrader: (43)

900 should be doable. might need more boost. is there a reason you dont want to run more than 15psi? a glide will rob less than th400.

yessir

iTrader: (5)

more boost than 15 psi, also depends on which 88 u have, i see 700whp thru a t56 at about 15lbs, but i do have less cam and im running 317 heads with a lil over 10-1 compression

yessir

iTrader: (5)

if you are dead set on 15psi you could run race gas and try to up the timing a bit, on my setup each degree was worth about 30 whp

Thirian24

No, I'm sure It could handle alot more boost. I'm just trying to stay conservative. Plus I don't want to run race gas, E85 or mess with meth.

Thirian24

What if I run the boost up to 20 and run a mix of 91 and c16?

Thirian24

Ok maybe the mix isn't a good idea because it wouldn't be consistent. How about water-to-air? Run some ice water? I don't know, just searching for ideas.

yessir

iTrader: (5)

i currently run pump and 14.8 psi to be exact at 10:1, so you might get a way with a lil more with you lower comp ratio

yessir

iTrader: (5)

btw when i say pump im reffering to 93 octane

Thirian24

Ok that sounds good, what's your thoughts on water-to-air?

Thirian24

Hey yessir, how does your T56 handle the HP numbers you are making. Did you change to steel shift forks, and what kind of clutch are you using? The reason I ask is because I have another 91 notch that is my weekend driver. I have a spare lq4 and t56 lying around. So I thought about doing H/C/I and doing that swap into my 91.

Fbodyjunkie06

iTrader: (10)

Here is the scoop.

Your set-up with good fuel(110+) would make well over 850rwhp. Your problem will be deck thickness with the L92 heads and lifting them off the block and pushing water.

At 15 psi you may be ok though but it will limit you to around 750-800 on pump and 850-900 on race gas.

A glide is way less robbing of power than any automatic tranny out there. Which is why they go into high hp racing apps and due to their low first gear helps get the high hp guys off the line.

If the motor hasn't been actually assembled I would look into getting the heads and block o-ringed so you can run more than 15 psi and meet your goals easily on pump and really turn it up on race fuel.

Hope this helps.

Thirian24

Fbodyjunkie06, please explain alittle more about the deck thickness and what cause this? Sorry for the noob question but thanks for any explanation.

Texas_WS6

iTrader: (9)

I run the same heads and a little smaller cam then you on my 408. Also I had installed the cam with the intake centerline at 105. It is a very simular build to yours. It was no issue to make 844rwhp and 817rwtrq with pump gas and 17psi. I have had no issue with the heads at this boost level, yet. I have changed the cam timing and a few other things (I had a stock LS3 manifold on it before and am now going with a single plane one like yours). All of this threw a 4L880E with a heavy billet convertor. I expect to see 1000+rwhp and rwtrq with all the changes with the same 17psi of boost. I am not sure the heads will hold but I will find out.

Like stated before, it will also depend on which 88 you have. I run the t-6 GT88 (old school) turbo. But I would expect to see 800rwhp at the least from your build, at 15psi. It will also depend on were you set your ICL up at too as well as how high do you plan to turn your beast.

I run Air to Air down draft intercooler, 3.5" charge piping now, and use water/meth injection. My air temps new go over 100 degrees.

Good luck, I bet it will do what you want it to do, and then some.

Texas_WS6

iTrader: (9)

Side note, I do run a wider lobe seperation then you and a reverse patter cam. I like to keep the valve overlap down as much as I can for a turbo car.

Fbodyjunkie06

iTrader: (10)

Deck thickness is how thick the deck of the head is where it meets with the block. The thicker the deck the more "meat" the head stud/bolt has to hold the head down on top of the block when a lot of pressure is applied during combustion.

The extreme pressure of running high boost without proper cylinder head sealing due to thin deck heads, not having head studs, and or a non-oringed block at these high boost levels. When all that pressure is crammed into the cylinder and there isn't sufficient clamping force to hold the head down, the pressure will find the weakest point to escape and that in this situation is the head gasket/deck surface area that seals on top of the block.

Detonation, high boost levels, thin decks, no head studs, not being o-ringed and high boost levels or not having 6 bolt heads all can contribute to heads lifting off the block.

If you keep it turned down to no more than 15-17 psi I don't think you will have any problems hitting your goal with the said boost pressure.

Hope this helps.

Texas_WS6

iTrader: (9)

Everything Fbody said is true. 15-17psi with the right head bolts, head gaskets, block prep, head prep, and correct assembley procedures should be fine for your stated goals.