LQ$ 6.0 - LS6 heads

**Edward-T** · 08-12-2011, 02:49 AM

ok, i have a LQ4 6.0 with a TSP torquer V2 cam and i just put LS6 heads on it and it has an LS6 intake as well, my question is - is it now an LS2/6 or is it just an LQ4 with LS6 heads? probably a dumb question but i was just wondering. lol

**ls1camino** · 08-12-2011, 06:57 AM

Personally, I'd tell people it was stock and let them figure out the hard way.

I'd just say it's a LQ4 with LS6 topend.

**Edward-T** · 08-12-2011, 07:05 AM

lol, yea i thought of that, thanks bro.

**98maro** · 08-12-2011, 08:18 AM

I kinda wanna get the same motor with the same heads as you. Idk bout the cam yet. Do you know what's your hp?
How u like that setup?
Thanks man

**Edward-T** · 08-12-2011, 08:22 AM

well before i put the heads on it was 423, but thats maxed, it had a conservative tune when i bought it and it was 402 whp and 396 wht, not sure what it is now, getting a new tune shortly but there is a 2-3 week wait for a dyno tune in my area.

**98maro** · 08-12-2011, 08:26 AM

Those are nice numbers. Post the results when you get a new tune pls.
Are u M6 or A4? Stock gears?

**Edward-T** · 08-12-2011, 08:37 AM

M6 with 410 gears

**Firebirdjones** · 08-12-2011, 08:42 AM

You basically put heads on with a smaller combustion chamber and bumped the compression. The LQ4's came factory with 317's, which is patterned exactly off the LS6 heads, same 210cc intake runner, same D shaped exhaust ports etc... etc.... With the only real difference being the larger 72cc combustion chamber that gave you a 9.4:1 compression ratio with your dished piston LQ4.
You were actually making decent HP numbers running that cam with such a low compression ratio.

The LS6 heads have a 64-65cc combustion chamber, and is also shaped differently which makes it more efficient, shortens burn time, and requires less ignition lead. So you are going to pick up "some" power just with the compression bump and better combustion chamber alone. That is unless these LS6 heads have been worked on. Then the change will be more significant.

**Edward-T** · 08-12-2011, 09:07 AM

well they have a 5 angle valve job and 64 cc chambers with 2.08 intake and 1.60 exhaust and 660 lift springs, so whats that good for?

**Firebirdjones** · 08-12-2011, 09:18 AM

Well if someone has installed 2.08 intake and 1.60 exhaust valve, then I would suspect at a minimum they have had some bowl work done to blend the cuts they made in the valve seats for the larger valves. That's usually normal procedure but not necessarily. The fancy valve job will also help.

In stock form the LS6 flows these numbers.....

Int.
lift
.100 = 62
.200 = 126
.300 = 184
.400 = 224
.500 = 251
.550 = 256
.600 = 257

exh.
lift
.100 = 57
.200 = 108
.300 = 143
.400 = 163
.500 = 176
.550 = 180
.600 = 183

These numbers are similar but not exact to the 317's you pulled off. Since you've had some work done on the new 243's these numbers will change, hopefully for the better. Without flow numbers on your heads it's hard to say how much of a change you'll see, but your dyno session will be intersting for sure.

**Edward-T** · 08-13-2011, 02:24 AM

Stage III Heads

Technical Specs:
Combustion Chamber: 64cc
Intake Runner: 227cc
Exhaust Runner: 70cc
Intake Valve: 2.08''
Exhaust Valve: 1.60''
Max. Valve Spring Lift: 0.650''
Spring Pressure Closed: 135 lbs. @ 1.800''
Spring Pressure Open: 375 lbs. @ 1.090''
Retainer Material: Titanium
Valve Seal Material: Viton
Valve Guide Material: Manganese Bronze
Valve Job: 5-angle

this is the info i have on them, i am at work but i will go out to the truck and see if i can find the flow sheet that came with the heads.

**Firebirdjones** · 08-13-2011, 06:38 AM

Ah, 227cc intake runners. They have been extensively worked then.

**Edward-T** · 08-13-2011, 06:51 AM

so they should make great power then? havent hit the dyno but i know on the street when i matt it and it gets above 3 grand and climbing (3rd gear floor) the rear is fighting hard for traction and the front nose is up in the air and its pulling massively hard, i love it!!

**Firebirdjones** · 08-13-2011, 06:57 AM

I would say so. I'm betting those heads should flow 300+ cfm. Most of the cathedrals do when done.

**Edward-T** · 08-13-2011, 07:01 AM

that sounds familiar from when i read the included flow chart, i went out at break and cant find the chart in my truck, must be at home somewhere, seems like the best i can remember it said 320 cfm but not sure till i find the sheet, but thanks for the responses, cant wait to put the beast on the dyno and sharpen it up a little.but my original question was because my blackbird stripes say 425 hp so when i redyno that will be wrong and was wanting to put the engine size in the stripe but is it still an LQ4 or is it closer to an LS2/6?

**Firebirdjones** · 08-13-2011, 07:48 AM

Originally Posted by Edward-T

that sounds familiar from when i read the included flow chart, i went out at break and cant find the chart in my truck, must be at home somewhere, seems like the best i can remember it said 320 cfm but not sure till i find the sheet, but thanks for the responses, cant wait to put the beast on the dyno and sharpen it up a little.but my original question was because my blackbird stripes say 425 hp so when i redyno that will be wrong and was wanting to put the engine size in the stripe but is it still an LQ4 or is it closer to an LS2/6?

Well I think you can call the engine what ever you want

An LQ4 has a cast iron block, an LS2 is aluminum. Both of them have a 4 inch bore which is what gives them 364 cubes over the LS1/LS6 at 346 cubes which has a 3.9" bore.
They all have the same stroke.

What ever you call it, it's still a 6.0 litre (364 cubes) with a 4 inch bore. If you really want to put an engine callout on the car, to be technically correct, LQ4 is what you have, but that would look a bit odd as an engine callout. I think a simple 6.0 callout would look better than the GM designated RPO number. OR,,,,if you like the HP callout, wait till you dyno it. I think you'll be close (if not more) to 450 rwhp. If it's in the ballpark then I'd just put 450 on the car.

At least the litre number is a nice round number. Putting the ci size of 364 also would look odd to me, just like 346 looks odd to me. That's why gm called the LS1 5.7 litre even though technically it's not. It's just marketing and 5.7 has been around since 1967.
These type of questions usually don't get answers people want to hear from me because I'm old school. 346 and 364 are just strange engine sizes to see on a car.