more HP from LQ4

[KEWLKATDADY]

I've done a ton of research, now for some specific questions.

I've got a 2004 LQ4, iron block aluminum head (317 heads) 9.4:1 stock motor.

It's going in my '67 c10. I'm not wanting to through a ton of cash at performance parts so I'm going to consider this a budget build.

It will be mostly street driven with some passes on the track here and there.

After the research, I'm thinking about swapping heads to P&P 243/799, long tubes, CIA, cam to match. Stock rebuild on the lower end and a flat (LQ9 style) piston to raise the CR into the 10+ range.
I'm hoping the truck intake will still be a good option for this set up.

Any other mods that I'm not thinking about here? I'm looking for a good street truck with a little thump. Hopefully with the heads, cam, exhaust and a good tune end up in the low to mid 400's HP.

Thoughts?

[HemiChallenger71]

Originally Posted by KEWLKATDADY

low to mid 400's HP.

Thoughts?

You can do that with just a camshaft, pushrods and valve spring upgrade. No need to touch anything else.

[KEWLKATDADY]

with the 317s?

[Super73]

Are we talking rwhp or flywheel-whp?

You did not mention what trans you have. Believe me, that will show a big difference in power from one to the next trans platform.

What wheels and tires, as that has a play in rwhp as well.

Stock for stock compared to the 317's, the 243's are simply a better head all around and will make more power exery where.
Smaller chamber = more compression
Better flow if both heads are in stock form

Back in 2002 I made 405rwhp with just a cam and headers in my 01 SS M6 car. That cam was medium sized by today's standards.

My truck however with ported heads, same ci, bigger cam and more compression barely made 410rwhp through a locked 4L80E. I eventually changed some things and got it to make 449rwhp and run 11.4x NA with an overly tight converter.

[BR3W CITY]

You can also keep the 317's and have them milled just slightly. It won't kill PTV clearance and you can still fit a hearty cam in there.

Fwiw, cam only (no longtubes) I was over 400crank hp. When I switched to SD, that increased even further. I've got some worked 317's and longtubes for this spring, and I should be well over 400 at the wheels through my 4l80e. You can hit 400 on 317's even if they are stock, it just takes more "supporting" mods.

[slowcpe]

While I currently do not have any real world experience, my current "plan" is:

Stock LQ4
4l80e w/3400 ish stall
243/799s milled, cleaned up and valve job (this alone with the lq4 pistons should get you close to 10.5:1)
BTR Stage 3 or 4 cam
Truck intake with 36lb range injector
Hopefully long tubes
All the other supporting mods

While I don't have a hp goal as I don't want to look foolish if I'm off, but I figure it should make enough power to be fun to drive and reliable without breaking the bank too much.

[KEWLKATDADY]

Originally Posted by Super73

Are we talking rwhp or flywheel-whp?

You did not mention what trans you have. Believe me, that will show a big difference in power from one to the next trans platform.

What wheels and tires, as that has a play in rwhp as well.

I have a 4L80e from the same truck that'll need to be rebuilt. I'm sure I'll have a chance for some upgrades while there, but I'm focusing on the motor research at this point, the transmission will come later.

So with that said I guess I'm talking flywheel HP, realistically I'm not sure if this truck will ever be on a dyno, so really the most important dyno is the butt dyno.

[Super73]

An LQ4 with the following mods should make over 400hp at the crank:

Un-milled Stock Heads
1 7/8 headers -> 3" x-pipe
Stock truck intake -> ported throttle body
Mid/high 23x duration cam

My first set up in the truck was:
Forged 347 bottom end
Stock 243 heads -> 10.25-1 cr
1 3/4 stepped to 1 7/8 headers -> 3" Xpipe
Stock LS6 intake -> stock throttle body
My custom 223/228 108/108 cam

This made 368rwhp through an 80E that has a stock converter, 8" steel wheels with 275/50/15 drag radials.

By no means was it a crazy build, but assuming a low 15% loss through drive train, that was 425ish at the crank. I felt the 80E was closer to 20% meaning 440ish at the crank.

[tinydb84]

My brother just finished having his engine assembled. lq4, 243 heads, LS6 intake, and a 230ish cam with 575ish lift, 113 LSA. At the rate he gets stuff done we should have the dyno numbers in oh about 3 years... lol

If I was to do it I would be cheap and just mill the 317's, run a truck intake, and go with some advance ground into the cam.

[Super73]

I have an idea on a cam for a stock 317 headed LQ4 that I think would work very well. This would be designed for:

9.5 static compression
1 7/8 headers with 3" x pipe
Stock manifold and ported TB

It looks odd looking at just duration and ICL/LSA. But you have to understand valve events to get it. I'll try and explain.

231/240 .598/.588 105icl and 115lsa
Comp lobe numbers 13045/3653

.050 numbers
IVO = 10.5 BTDC - This is as early as I would open it due to piston to valve clearance concerns. Maximizes cyl fill due to time spent open.
IVC = 40.5 ABDC - Keeps Dynamic compression up, closes early enough to keep peak HP at a respectable rpm (6,000-6,200) Makes a lot of power under the curve
EVO = 65 BBDC - Spent gasses need time to evacuate the cyl. This gives plenty of time for the cyl to clean out.
EVC = 5 BTDC - Maximizes cleaning out the spent gasses and provides a little overlap to start pulling the intake charge through. Too much overlap hurts bottom end do to reversion.
Overlap = 5.5
Dynamic compression based on 9.5 static compression = low at 7.4

Raising compression to 10.5 static would probably pick up 10-15 ftlbs/hp across the full curve. 91 octane would still work as dyn compression would only be 8.16.

[Wasted Income]

Here are some real world numbers from a car I built a few years ago.

Engine Details:
2002 LQ4
Stock untouched 317s with dual valve springs
XR281HR, 228/230, .571"/.573" - 112 LSA
Hardened pushrods
LS6 intake with stock truck cable TB
LS6 injectors
0411 PCM tuned Open Loop, Speed Density by me
1-3/4" longtubes

Other Details of the car:
3" true dual exhaust
4L80E with a 3400 stall
3.42 gear, 8.5" 10-bolt Grand National Axle


This combo made 409 rwhp on the motor, and 536 rwhp on the jug. It has been stone reliable, even with about 30 bottles of dope run thru it.

https://www.youtube.com/watch?v=5YLgLyPRh3w

Monte Carlo with an LSX swap - YouTube

[Super73]

Respectable numbers.
Any idea what the ICL was on the cam?
NA, what rpm did the motor make peak TQ and HP?

[HemiChallenger71]

Thanks wasted.

[Wasted Income]

110 degree ICL

Here is the cam card
http://www.compcams.com/Company/CC/c...csid=1091&sb=2

I don't have the dyno sheet in front of me, and can't remember the rpm for the peaks.