Yet another LQ4 build...questions
Yet another LQ4 build...questions I've been looking without luck for a while to try to find the info I need, but alas I'll post here in hope of some helpful feedback.
I'm building a boosted lq4 (shooting for 15-20psi), and am really having trouble deciding which way to go with regards to heads and a few other things. I've really been taking a close look at the l92 heads, and already went as far as to order the needed intake (L92/L76/LS3) for the project. I'm shooting for 600rwhp, as smooth an idle as possible, and daily driveablilty.
I've been looking at various companies for connecting rods, and have decided on either Callies or Scat h-beams. I'm having a difficult time determining what size the stock rods are (haven't taken the engine apart all the way yet)....anyone here know? I'm guessing that the LS1 rods are the same length, but I'm not sure (no one lists for the lq4). As for the pistons...I would like to have a static comp of 9-9.5(maybe lower, if it's workable), but am not sure if the efficiency of the L92 heads will suffer....making the heads a pointless addition??
Lastly, cam selection. I've been thinking of using the "Hot cam" or z06 cam, but am open to suggestions. Again, I'm trying for 600rwhp (but hey, more is good!) with a relatively smooth or "slightly-modded" idle/sound. Any suggestions here? I know that I'm kinda "wanting it all" with regard to power/driveablity, but this car is going to be a semi-daily driver so I want it to drive with as many street manners as possible.
Any thought? Let's hear 'em!
I'm building a boosted lq4 (shooting for 15-20psi), and am really having trouble deciding which way to go with regards to heads and a few other things. I've really been taking a close look at the l92 heads, and already went as far as to order the needed intake (L92/L76/LS3) for the project. I'm shooting for 600rwhp, as smooth an idle as possible, and daily driveablilty.
I've been looking at various companies for connecting rods, and have decided on either Callies or Scat h-beams. I'm having a difficult time determining what size the stock rods are (haven't taken the engine apart all the way yet)....anyone here know? I'm guessing that the LS1 rods are the same length, but I'm not sure (no one lists for the lq4). As for the pistons...I would like to have a static comp of 9-9.5(maybe lower, if it's workable), but am not sure if the efficiency of the L92 heads will suffer....making the heads a pointless addition??
Lastly, cam selection. I've been thinking of using the "Hot cam" or z06 cam, but am open to suggestions. Again, I'm trying for 600rwhp (but hey, more is good!) with a relatively smooth or "slightly-modded" idle/sound. Any suggestions here? I know that I'm kinda "wanting it all" with regard to power/driveablity, but this car is going to be a semi-daily driver so I want it to drive with as many street manners as possible.
Any thought? Let's hear 'em!
the lq4 uses same length connecting rods and same stroke as ls1
6.098 rods and 3.622 stroke
the lq4 is 9.5:1 scr stock with 8cc dish piston
many sponsors offer forged pistons and rods for lsx engines.
u can order 4.00-4.030, etc. pistons for use with forged rods
6.125 length or 6.100 length and the appropriate compression height piston for either rod.
the z06 cam should work excellent with the l92 heads, since the l92 seem to favor long duration exhaust cams
6.098 rods and 3.622 stroke
the lq4 is 9.5:1 scr stock with 8cc dish piston
many sponsors offer forged pistons and rods for lsx engines.
u can order 4.00-4.030, etc. pistons for use with forged rods
6.125 length or 6.100 length and the appropriate compression height piston for either rod.
the z06 cam should work excellent with the l92 heads, since the l92 seem to favor long duration exhaust cams
the lq4 uses same length connecting rods and same stroke as ls1
6.098 rods and 3.622 stroke
the lq4 is 9.5:1 scr stock with 8cc dish piston
many sponsors offer forged pistons and rods for lsx engines.
u can order 4.00-4.030, etc. pistons for use with forged rods
6.125 length or 6.100 length and the appropriate compression height piston for either rod.
the z06 cam should work excellent with the l92 heads, since the l92 seem to favor long duration exhaust cams
6.098 rods and 3.622 stroke
the lq4 is 9.5:1 scr stock with 8cc dish piston
many sponsors offer forged pistons and rods for lsx engines.
u can order 4.00-4.030, etc. pistons for use with forged rods
6.125 length or 6.100 length and the appropriate compression height piston for either rod.
the z06 cam should work excellent with the l92 heads, since the l92 seem to favor long duration exhaust cams
any suggestions on a cam profile that might be a little "more" in terms of gains, yet still maintain nice driveablilty?
lingenfelter gt11 cam is a aggressive low duration high lift cam with 230* exhaust duration, it is very responsive in a n/a car and should be even more with psi and hi flow l92 heads.
imo i would just add arp rods to the lq4, strong springs and hi volume,hi pressure oil pump, arp head studs, l92 mls gaskets to the stock lq4
with the l92 heads and run up to 10psi
with a safe correct tune, 60 lb. injectors, and some meth
combo should be over 500rwhp on 93 octane
imo i would just add arp rods to the lq4, strong springs and hi volume,hi pressure oil pump, arp head studs, l92 mls gaskets to the stock lq4
with the l92 heads and run up to 10psi
with a safe correct tune, 60 lb. injectors, and some meth
combo should be over 500rwhp on 93 octane
lingenfelter gt11 cam is a aggressive low duration high lift cam with 230* exhaust duration, it is very responsive in a n/a car and should be even more with psi and hi flow l92 heads.
imo i would just add arp rods to the lq4, strong springs and hi volume,hi pressure oil pump, arp head studs, l92 mls gaskets to the stock lq4
with the l92 heads and run up to 10psi
with a safe correct tune, 60 lb. injectors, and some meth
combo should be over 500rwhp on 93 octane
imo i would just add arp rods to the lq4, strong springs and hi volume,hi pressure oil pump, arp head studs, l92 mls gaskets to the stock lq4
with the l92 heads and run up to 10psi
with a safe correct tune, 60 lb. injectors, and some meth
combo should be over 500rwhp on 93 octane
Running the l92 heads on the lq4 will give me right at 10:1 comp....a bit higher than I want for a turbo engine. Do you think going with 9.5 pistons would mess too much with the "quench" area?
Last edited by salemetro; Sep 27, 2008 at 07:43 PM.
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NemeSS....that Lingenfelter cam looks SWEET! Thanks for the lead...I'm going to consider it. Begs the questions of stainless or titanium retainers/keepers though. Many valve companies do not recommend Titanium for longevity...primarily less weight reasons for all out racing. Any thoughts??
Just out of curiosity: Does anyone know if there are people running 15+ psi on the lq4?
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gt11 build i have run the gt11 with patriot gold duals fro thousands of miles,
spray and 7k rpm, no issues or problems
im actually building a lq4 engine with this cam.
its a .060 over lq4 with .015 out the bore,
gm l92 mls 4.085 .053 compressed (.038 quench)
lq4 dish replacement pistons 10cc spherical dish
243 heads milled .030
with victor jr,elbow,90mm tb with perimeter n20 plate
th350,3800 stall tq converter
the cam pulls hard in a 346 ls1, with a m6
with lt's and ls6 intake
spray and 7k rpm, no issues or problems
im actually building a lq4 engine with this cam.
its a .060 over lq4 with .015 out the bore,
gm l92 mls 4.085 .053 compressed (.038 quench)
lq4 dish replacement pistons 10cc spherical dish
243 heads milled .030
with victor jr,elbow,90mm tb with perimeter n20 plate
th350,3800 stall tq converter
the cam pulls hard in a 346 ls1, with a m6
with lt's and ls6 intake
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Joined: Sep 2008
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Go with 10.1 with less boost and more timing. You'll make just as much HP this way as you would with 9.5:1 and more boost and less timing.
Keep your quench large. .050-.060. This will slow the flame front with pump gas and allow more timing all while keeping detonation away.
L92 heads are nice but in terms of blown applications, all the things nice about N/A heads don't matter. Port velocity, unshrouded valves, blah, blah.....doesn't matter. Straightest shot, most unrestricted flow into the cylinder is what you're looking for.
Any cam that has a bumb to it is quickly smoothed out with a blown application. A 232/234 on a 111LSA will sound like a 224/228 on a 114LSA.
Keep your quench large. .050-.060. This will slow the flame front with pump gas and allow more timing all while keeping detonation away.
L92 heads are nice but in terms of blown applications, all the things nice about N/A heads don't matter. Port velocity, unshrouded valves, blah, blah.....doesn't matter. Straightest shot, most unrestricted flow into the cylinder is what you're looking for.
Any cam that has a bumb to it is quickly smoothed out with a blown application. A 232/234 on a 111LSA will sound like a 224/228 on a 114LSA.
I agree with LLC. The large intake/exhaust valve size ratio of the L92 heads does not help that much vs. other heads. The turbo setup kind of negates the advantages that these heads offer. However, they are still pretty cheap at $800 a set. Personally, I'd run a few points less compression (or timing at the very least), although I'm not much of a forced-induction guy (NA all the way!). Just my $.02 (which is probably only worth about $.0002 with our current economic situation)
Oh, and I've heard of aluminum blocks holding to about 700 flywheel hp, and iron even more. Much of the concern lies in head gaskets when you start adding psi to the equation (again - I don't know this from experience. I like NA, but I've talked to my fair share of engine builders).
-TW
Oh, and I've heard of aluminum blocks holding to about 700 flywheel hp, and iron even more. Much of the concern lies in head gaskets when you start adding psi to the equation (again - I don't know this from experience. I like NA, but I've talked to my fair share of engine builders).
-TW
