View Full Version : Turbo LQ4 Build...Need some help.

04-17-2012, 06:15 PM
So I've been searching and reading on here for the last 2 weeks and was stuck between doing a LM7 or a LQ4 build for my 71 Chevelle. Still had some questions/unsure about a few things...thought I should start a thread just make sure I'm on the correct path. Please keep in mind I don't have much experience with Chevy/V8 stuff...only Audi's (smallish turbo motors 1.8T, 2.7T)

Planned project:
Car: 71 Chevelle (Pro touring style build)
Engine: LQ4
Trans/Rear: Corvette C5 6spd and differential (stock gear ratios)
Suspension: C5 suspension (spindles/brakes/axles/etc...)
Goal: Turbo motor with 550-575whp to start, then crank up boost for 800+whp once I upgrade the transmission and rear end down the road.
Wight: I'm guessing somewhere between 4000-4100lbs
Purpose of car: Fun street car...will not see too much time at the strip/track, maybe once or twice if that. Plan on actually driving this car quite a lot.

I was stuck on the LM7 (wanted better gas mileage) but decided to go LQ4 for better choice of pistons (for 8.5:1 CR) and ease of build (planning on assembling engine myself).

Build plans:
So far, I'm planning on purchasing Forged rods (Compstar 6.1") and pistons (Diamond or similar 4.0xx" -15cc) with stock crank (keeping it 6.0L and bringing compression down to ~8.65 (according to my calculations)), new bearings, ARP main bolts/head bolts, and new oil pump. I will get the rotating assembly balanced and have the main caps pinned. Planning on keeping the stock heads and buying a cam and valvesprings, havn't decided on which way to go with this. For the turbo I'm planning on going with S400SX-76R BILLET* 83mm Turbine. I will be running Meth injection with 91octane (CA shitty 91oct)

What I've got so far:
1) Hogan's intake manifold.
2) LQ4 engine (still have to pick it up) with 70K miles with all accesories and no ECU/Accesories.

My questions:
1) Am i on the correct path with my plans for the block/engine?

2) Will the Hogan's manifold work with the LQ4 (317) heads? I've read that the LQ4 heads are Cathedral port and the ports on the mani look rectangular...but I've also read that the ports on LQ4/LS1 intake manifolds are rectangular as well? Can anyone verify this? I guess I already have the manifold and if it doesn't work which heads will it work with? Pics of manifold below.

3) What cam should I go with. I want to spin the motor to 7200RPM and have top end power. I also do care about the sound and am willing to sacrafice a little bit of hp for it. I love that lopey sound.

4) Any feedback on if this turbo is the correct choice? Can't find any compressor maps for this turbo. Don't want to go bigger than I need to, want to keep it responsive as possible for the hp goal.

5) What are the best choices for ECU/ECM. I can go either standalone that I am familiar with (works with LS coils/sensors but doesn't have knock sensors), OR get a LS harness and ECU with HPTuners or similar? Can the sensors (including MAF) be disconnected/removed and still tuned well with HPTuners? Any good tuners in SF Bay area? What about sequential injectors?

04-17-2012, 06:15 PM
P.S: Sorry for the long essay but wanted to provide all the info in hopes of getting quality answers. Thanks!

Hank Peabody
04-17-2012, 08:24 PM
Smallest turbine possible to meet your goals, I have a 6.0 too. I just went from an auto to a manual and boost is way way way slower feeling with the manual. With an auto the boost was really instant, with the manual I have to actually wait until you get to 3000rpm before you start making any real boost.

Borg Warner S400 with T4 87mm turbine would be the biggest I'd go, 80mm compressor would be great for 800whp. I'd probably try an 80mm compressor S400 with 83mm turbine before the 87mm turbine, alot cheaper too.

04-18-2012, 08:40 AM
go with the 75mm borg warner with the T6 1.32 hot side and 96 mm turbine wheel, a 6.0 will choke a t4 turbo.

Hank Peabody
04-18-2012, 10:25 AM
145mph at 3300# with a T4 on a 6.0, sounds choked? :jest:

04-30-2012, 12:10 PM
Bumping back up...hoping for more feedback.