KILLER-LS1

iTrader: (18)

Hey everyone... I want to see if any of you have any advice for me to get a little more power out of my set-up. First, here are some specs:

404ci iron block 4.010" bore x 4.000" stroke
eagle forged crank
eagle forged rods
Mahle -12cc forged turbo pistons
Comp custom grind - 231/227 .617/.614 116 lobe separation
ARP main studs, head studs, rod bolts
LS9 (7-layer) MLS Head gaskets
Edelbrock Pro-Port Heads CNC'd by WCCH. 215cc intake, 87cc exhaust, 74cc chamber
Patriot Gold Dual springs set up and shimmed by WCCH
Comp pushrods, comp lifters, stock rockers
Edelbrock Vic Jr. Intake, elbow, 90mm TB
MSD coils & wires
NGK TR6 plugs gapped at .030"

Turbonetics 78mm with .96a/r on a T4 truck manifold set-up.
Turbosmart 50mm wastegate

If you want to see pics of my build, I have a sticky at the top about my truck manifold set-up here: https://ls1tech.com/forums/forced-in...ifold-kit.html

Or pics of my motor and heads here: https://ls1tech.com/forums/western-m...ions-pics.html


Now this is in a STREET car. it sees 99% street use. I drive it almost daily. It dynod at 10psi at apx 580 rwhp and 680rwtq.

on the street, I see 12-13psi however, so i figure im at least looking at 600rwhp and 700rwtq. I just think it should have a little more power with that much boost. the tuner said i had enough fuel, but even he thought I should have more power. And fyi, I know nothing about the tune. Thats the one thing that I didnt do on my car, so i cant tell you the timing or anything like that :-/

let me know if you want to know any other specs! I appreciate it!

~Josh

98Z28CobraKiller

iTrader: (17)

Without seeing the graph but seeing the numbers, sounds you are laying over up top. I suspect that the first choke point is the exhaust housing.

transammiller

iTrader: (21)

that thing is a monster. is it a diesel. that's great torque for your setup. whats your compression? you can always add more power by upping the compression then you have to worry about timing at higher psi. and you can fix that with METH. I'm stuck with 15 psi so i am just gonna up the compression and add meth.

KILLER-LS1

iTrader: (18)

Thats exactly what we were thinking, but I spent an hour at the SEMA show talking to one of the turbonetics engineers and thats what he recommended for a street car. This car honestly spools INSTANTLY. I love it, but I realize I cant have the best of both worlds.

It made peak torque at like 3900rpms!! its so fun to drive, but im just wondering if i have more power hidden somewhere.

Maybe I can buy a spare exhaust housing and swap them out when I want to go to the track???

98Z28CobraKiller

iTrader: (17)

T6 1.15A/R+ would get that hp up closer to the torque. That little cam is also exaggerating your torque at the expense of hp. That intake should pull to 7K RPM.

Johnv

+ 1 on the exhaust housing AR being the 1st bottleneck.(turbo is a little small full stop for a 404 ci)

My 383, tc 78, .96AR, Would lay over around 5000 rpm, went to a 1.32 ar and now pulls to the limiter 6800 rpm with negligable difference in spool time.

get a bigger housing or upsize turbo

KILLER-LS1

iTrader: (18)

I guess what im wondering is, since im not using my car competitively, should I just leave it alone? and also that cam was spec'd specifically for good street torque. I was very specific when explaining how and when I use my car, and I am almost never above 6k. The vic jr manifold was more for the wow factor when looking in the engine bay than anything else lol. but without sacrificing the low end power this thing has, are there any other smaller changes that could help?

TurboS10

iTrader: (12)

Biggest down pipes and mufflers you can stand.
E housing
WG to atmosphere.
PT88h
Twins

The .96 S wheel lays down on a 355 at about 5k so you're doing good with the 404.
https://ls1tech.com/forums/forced-induction/1059779-78gts-vs-pt88-dyno-overlay-inside-same-motor.html

KILLER-LS1

iTrader: (18)

Link doesnt work.

TurboS10

iTrader: (12)

wtf!
How can it post correct and link wrong...."forced-induction" is missing in the link
https://ls1tech.com/forums/forced-in...ame-motor.html

forcd ind

iTrader: (7)

you have close to my build, 403 w/225 AFR heads, EPP cam though, and a
D1SC-i made 617 @ 6400, 517 tork @ 6000, 11 lbs on a chassis dyno, with a hi stall, but i run a carb-i thought my #'s would be higher, based on what all i saw on here-def thought the tork would be higher, but at the hit on the chassis dyno, it was stalling pretty high, so thats where we started the tests
@ 3900 lbs w/me, (chevelle) i have been 9.92 @ 135 pretty much street trim, since i only have a 6 pt bar 10.0 is the bottom anyway-but the driveability is unbeliveable, so thats more important than the #'s
i guess everbody would have to run the same day on the same dyno to really compare dyno #'s-i just used it as a tuning gauge, you know how hard it is to run wide open on the street, lookout for trees and read gauges, lol

98Z28CobraKiller

iTrader: (17)

A bigger exh housing may move peak torque up a couple hundred RPM but it will pull way harder up top. I bet you wouldn't notice if you lost 50 ft/lbs down there anyway as no traction is no traction.

You can't draw any comparisons between your setup and his. 2 completely different principles at play here.

bonnarls1

iTrader: (20)

are tr6 plugs the right plugs for that setup????

98Z28CobraKiller

iTrader: (17)

I would use a 7 and once it's uncorked, an 8.

mike13

iTrader: (27)

I can give you a first hand account of how restrictive that housing is.

383 (stroked ls)
patriot heads
224/230 .581 cam
TC76 .96 a/r
spool instantly, pull hard in the midrange 4500 and up felt like someone pulled all the timing out of the motor. Went with a borg warner ST80 1.25 a/r sluggish on the bottom pulls clear to redline hard, it's now scary fast on top.

I would seriously consider a larger turbo or at the very least a larger turbine housing, turbonetics is a great company but I've noticed their reps seem to underestimate how well the LS motors flow, much better to have someone familiar spec out a turbo. I would talk with Forced Inductions they deal with this issue all the time.

I was just reading your engine spec's again and wanted to edit my post, that's a large cam you have with a fair amount of overlap, by having a large amount of backpressure your really getting a double whammy, when that cam should come into it's sweet spot is when your backpressure will be stiffling the engine.

TurboS10

iTrader: (12)

He's got a single 68mm turbine on 404.......Needs at least an 75mm S turbine.

Facelift

Two words
MORE DECALS

KILLER-LS1

iTrader: (18)

its a 78mm....

TurboS10

iTrader: (12)

68mm turbine not compressor!
You said you got a;
Hurricane 7868 “Benita” 650-800 HP-78 4.0" / 2.5" F1-68 T4 0.96 A/R | 3” VB 11535
It's a good 5.3 turbo.

The F1-S is the HPS equivalent 75mm turbine.
The little S400-75 is a 83mm and up T4 or T6.

KILLER-LS1

iTrader: (18)

Oh sorry, yeah i read that too fast, youre right