Lq4 top end question
03-15-2009, 01:42 PM
#1
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Lq4 top end question I have a Lq4 to put in my 99 Silverado to replace a 4.8. The truck has a 5 speed and 3.42 gears.
I plan to have this motor in there to help with pulling my chevelle and to have fun with when not towing the chevelle.
I was thinking of just installing it as is and put some long tube or shorty headers on the 6.0.
Question:
I have LS2 cam I can install in the LQ4, but I don't want reduce the torque. I think the cams are very close in duration.
Should I just leave the cam alone?
Should I use a different head gasket to bump up the 9 to 4 compression to say around 10 to 1?
Should I use my 4.8 heads instead to bump up compression?
Should I port the heads?
How far down in the hole are the LS pistons? I know the Lq4 is a dished piston, but I don't know the piston volume? Anyone?
The LS series is new to me. However I do have some experience with BBC and the older SBC motors.
Opinions please?
I'm wanting around 400 horse and 400 ft lbs of torque.
I plan to have this motor in there to help with pulling my chevelle and to have fun with when not towing the chevelle.
I was thinking of just installing it as is and put some long tube or shorty headers on the 6.0.
Question:
I have LS2 cam I can install in the LQ4, but I don't want reduce the torque. I think the cams are very close in duration.
Should I just leave the cam alone?
Should I use a different head gasket to bump up the 9 to 4 compression to say around 10 to 1?
Should I use my 4.8 heads instead to bump up compression?
Should I port the heads?
How far down in the hole are the LS pistons? I know the Lq4 is a dished piston, but I don't know the piston volume? Anyone?
The LS series is new to me. However I do have some experience with BBC and the older SBC motors.
Opinions please?
I'm wanting around 400 horse and 400 ft lbs of torque.
03-15-2009, 05:57 PM
#4
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Pistons are -6cc
Use the 5.3 heads with bowl blending and larger int valves (stock LS1 size)
Stock head gasket will get you 10.5:1 compression (with the above head)
400 would be easily made if you get the compression up and toss in a z06 cam w/o losing anything down low
Oh yeah keep the truck intake too if you can, it flows the same as the LS6 intake but makes more TQ.
Use the 5.3 heads with bowl blending and larger int valves (stock LS1 size)
Stock head gasket will get you 10.5:1 compression (with the above head)
400 would be easily made if you get the compression up and toss in a z06 cam w/o losing anything down low
Oh yeah keep the truck intake too if you can, it flows the same as the LS6 intake but makes more TQ.
03-16-2009, 10:47 AM
#5
Question:
Answer
I have LS2 cam I can install in the LQ4, but I don't want reduce the torque. I think the cams are very close in duration.
Should I just leave the cam alone?
Leave the stock one in it, the LS2 has the cam sensor in the front and may require modifications to the LQ4
Should I use a different head gasket to bump up the 9 to 4 compression to say around 10 to 1?
No, 9.5:1 will allow you to run 87 octane and still make great power (with the right cam), although you can have the 317 heads milled to increase the comp ratio.
Should I use my 4.8 heads instead to bump up compression?
No, see above
Should I port the heads?
Yes, if your budgets allows for it, Also look into getting them milled. The 317 heads have similar ports to 243 heads, but with larger combustion chambers.
How far down in the hole are the LS pistons?
They stick out .005" or so.
I know the Lq4 is a dished piston, but I don't know the piston volume?Anyone?
-6cc sounds right
Opinions please?
Are you looking for 400hp/400tq to the wheels or at the crank? With a small torquey cam you will be very hard pressed to make 400rwhp, although it will make 400bhp. FYI: Since this is going on your truck, unless you want to modify the accessories, the truck intake is your only option.
Answer
I have LS2 cam I can install in the LQ4, but I don't want reduce the torque. I think the cams are very close in duration.
Should I just leave the cam alone?
Leave the stock one in it, the LS2 has the cam sensor in the front and may require modifications to the LQ4
Should I use a different head gasket to bump up the 9 to 4 compression to say around 10 to 1?
No, 9.5:1 will allow you to run 87 octane and still make great power (with the right cam), although you can have the 317 heads milled to increase the comp ratio.
Should I use my 4.8 heads instead to bump up compression?
No, see above
Should I port the heads?
Yes, if your budgets allows for it, Also look into getting them milled. The 317 heads have similar ports to 243 heads, but with larger combustion chambers.
How far down in the hole are the LS pistons?
They stick out .005" or so.
I know the Lq4 is a dished piston, but I don't know the piston volume?Anyone?
-6cc sounds right
Opinions please?
Are you looking for 400hp/400tq to the wheels or at the crank? With a small torquey cam you will be very hard pressed to make 400rwhp, although it will make 400bhp. FYI: Since this is going on your truck, unless you want to modify the accessories, the truck intake is your only option.
03-16-2009, 11:38 PM
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Question:
Answer
I have LS2 cam I can install in the LQ4, but I don't want reduce the torque. I think the cams are very close in duration.
Should I just leave the cam alone?
Leave the stock one in it, the LS2 has the cam sensor in the front and may require modifications to the LQ4
Should I use a different head gasket to bump up the 9 to 4 compression to say around 10 to 1?
No, 9.5:1 will allow you to run 87 octane and still make great power (with the right cam), although you can have the 317 heads milled to increase the comp ratio.
Should I use my 4.8 heads instead to bump up compression?
No, see above
Should I port the heads?
Yes, if your budgets allows for it, Also look into getting them milled. The 317 heads have similar ports to 243 heads, but with larger combustion chambers.
How far down in the hole are the LS pistons?
They stick out .005" or so.
I know the Lq4 is a dished piston, but I don't know the piston volume?Anyone?
-6cc sounds right
Opinions please?
Are you looking for 400hp/400tq to the wheels or at the crank? With a small torquey cam you will be very hard pressed to make 400rwhp, although it will make 400bhp. FYI: Since this is going on your truck, unless you want to modify the accessories, the truck intake is your only option.
Answer
I have LS2 cam I can install in the LQ4, but I don't want reduce the torque. I think the cams are very close in duration.
Should I just leave the cam alone?
Leave the stock one in it, the LS2 has the cam sensor in the front and may require modifications to the LQ4
Should I use a different head gasket to bump up the 9 to 4 compression to say around 10 to 1?
No, 9.5:1 will allow you to run 87 octane and still make great power (with the right cam), although you can have the 317 heads milled to increase the comp ratio.
Should I use my 4.8 heads instead to bump up compression?
No, see above
Should I port the heads?
Yes, if your budgets allows for it, Also look into getting them milled. The 317 heads have similar ports to 243 heads, but with larger combustion chambers.
How far down in the hole are the LS pistons?
They stick out .005" or so.
I know the Lq4 is a dished piston, but I don't know the piston volume?Anyone?
-6cc sounds right
Opinions please?
Are you looking for 400hp/400tq to the wheels or at the crank? With a small torquey cam you will be very hard pressed to make 400rwhp, although it will make 400bhp. FYI: Since this is going on your truck, unless you want to modify the accessories, the truck intake is your only option.
OK.. Hmm, I under the impression that the LS2 was a direct swap. How would it have to be modified?
If the LS2 cam is used. How much compression would it need? A increase of a .2 to .3?
Yes, I looking for 400 horse/torque at the flywheel.
Would just porting the heads get me to this goal?
What is the redline of a stock LQ4? Say 5000?
Thanks
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03-17-2009, 08:55 AM
#8
OK.. Hmm, I under the impression that the LS2 was a direct swap. How would it have to be modified?
The LQ4 has the cam sensor in the back of the block, the camshaft has two slots in the back. The LS2 uses four slots and it is in the front of the block, located on the timing chain cover. You would need an extension harness and a different timing chain cover, assuming nothing else happens. Plus you will ne a way for the ECM to interpret that signal from 4 pulses to 2 pulses on the LQ4 ECM. Too much hassle for an LS2 cam, it is not worth it. The LS6 cam has the same specs and is a direct bolt in.
If the LS2 cam is used. How much compression would it need? A increase of a .2 to .3?
The LS2 had 10.4 or so CR from the factory.
Yes, I looking for 400 horse/torque at the flywheel.
Would just porting the heads get me to this goal?
400bhp, then you would need 243 heads with an LS6 and full length headers.
What is the redline of a stock LQ4? Say 5000?
Depends on the intake used, if it is the stock truck intake it is 5500, as power peaks at 5000. Mind you, peak and redline are totally different.
The LQ4 has the cam sensor in the back of the block, the camshaft has two slots in the back. The LS2 uses four slots and it is in the front of the block, located on the timing chain cover. You would need an extension harness and a different timing chain cover, assuming nothing else happens. Plus you will ne a way for the ECM to interpret that signal from 4 pulses to 2 pulses on the LQ4 ECM. Too much hassle for an LS2 cam, it is not worth it. The LS6 cam has the same specs and is a direct bolt in.
If the LS2 cam is used. How much compression would it need? A increase of a .2 to .3?
The LS2 had 10.4 or so CR from the factory.
Yes, I looking for 400 horse/torque at the flywheel.
Would just porting the heads get me to this goal?
400bhp, then you would need 243 heads with an LS6 and full length headers.
What is the redline of a stock LQ4? Say 5000?
Depends on the intake used, if it is the stock truck intake it is 5500, as power peaks at 5000. Mind you, peak and redline are totally different.
03-18-2009, 09:01 AM
#9
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I just did a rebuild on my truck's LQ4. Here is a link http://www.performancetrucks.net/for...ht=clemsondave
I put in LS2/LQ9 flat top +0.030 pistons.
LS2 connecting rods (pistons above have floating pins vs stock LQ4 pressed)Got them on ebay
Stock GM MLS gaskets
Did not mill the stock LQ4 heads
This raised CR to 10.1:1 which is fine on 87 octane
I put in a custom grind cam ($379) 210/216 .555/.561 114LSA. LS6 springs, LS7 lifters. 7.425 pushrods.
Had Steve with LSxTune.com put his magic touch on it and it has tons of power.
I put in LS2/LQ9 flat top +0.030 pistons.
LS2 connecting rods (pistons above have floating pins vs stock LQ4 pressed)Got them on ebay
Stock GM MLS gaskets
Did not mill the stock LQ4 heads
This raised CR to 10.1:1 which is fine on 87 octane
I put in a custom grind cam ($379) 210/216 .555/.561 114LSA. LS6 springs, LS7 lifters. 7.425 pushrods.
Had Steve with LSxTune.com put his magic touch on it and it has tons of power.
