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1LE
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13,384 Posts
I read this too

And literally a week before reading it I was arguing with someone telling them to buy an LS2 GTO so they can run LS3 heads which flow the best lol

Now I'm not sure if I'm right or wrong.
They used aftermarket heads in that comparison.
Stock for stock Ls3 heads flow better than Ls2 heads.
 

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The Entenmann's Shim-Sham
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12,138 Posts
Yeah, a lot of people lose sight of the budget purpose of the LS3 head and tend to compare aftermarket/ported cathedrals and an aftermarket intake to a stock LS3 top end. All that article tells me is that someone with an existing cathedral head doesn't need to swap to a rectangle setup with an aftermarket casting and vice versa.
 

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The Entenmann's Shim-Sham
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12,138 Posts
What is your setup now?
 

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757 Posts
New LS3 heads worked over by Advanced Inductions milled .030"
Cam Motion Cam 230/238 .626 113+3
New LS3 intake modified by Rick Crawford
.040" cometic head gaskets
GM oil pump
Straubs trunnion kit
New GM rocker arms
Morel 5315 Lifter
BTR 5/16" pushrods 7.350"
BTR .660 valve springs w/ti retainers
ARP Head bolts
Improved Racing oil pump bracket and bolt
Ls2 Timing Gear and Chain
Spectre 4" tube and couplings with 100 maf sensor
misc. bolts and gaskets
changing from a vararam intake to X-Air
1 7/8" Kooks
LS3 injectors
p&p LS2 tb
Monster 2 clutch
 

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The Entenmann's Shim-Sham
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12,138 Posts
I'd get your factory TB ported. I don't think the cost of a 100mm throttle body is going to be worth the minimal gains.
 

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9 Posts
Noob here.

I think this cam is going to hit the pistons.
2006 GTO
LS3 heads milled 0.040
CNC w valve job new seals and guides and trunnion rockers with 1211 PAC beehive springs.
Comp 223/239 0.610/0.624 lift 114 LSL lobe. I believe its called the Avenger cam by Alvin at PCM
LS3 intake, LS2 throttle body, kooks 1-7/8 long tubes.
0.040 head gasket
GM CTSV-R ceramic ball lifters.
Bone stock 100,000 mile bottom end.

Please let me know your thoughts! Many thanks.

Update: well I think I might just have way too much exhaust lobe. Looking at this old post on this thread from 8 years ago (WOW)

The issue of the exhaust is why do people run extended exhaust durations? To compensate the restrictions or limitations in the exhaust effciency or system right? So you run a 224/230 which has a 6* split, which should address an exhaust effciency issue, then your running LT Headers, which also adresses an exhaust effciency issue.... And now the exhaust ports are fully ported.... Porting the exhaust port will show minimal or bleek gains here due to the fact that you have already addressed exhaust efficiency issues with the cam/exhaust duration and headers..... becareful as you can run into a situation where your TQ will decrease due to denser gas velocity slowing down due to the increase in port size....
 

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REDKEYN
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3,802 Posts
Discussion Starter #3,992
Noob here.

I think this cam is going to hit the pistons.
2006 GTO
LS3 heads milled 0.040
CNC w valve job new seals and guides and trunnion rockers with 1211 PAC beehive springs.
Comp 224/239 0.610/0.624 lift 114 LSL lobe.
LS3 intake, LS2 throttle body, kooks 1-7/8 long tubes.
0.040 head gasket
GM CTSV-R ceramic ball lifters.
Bone stock 100,000 mile bottom end.

Please let me know your thoughts! Many thanks.

Update: well I think I might just have way too much exhaust lobe. Looking at this old post on this thread from 8 years ago (WOW)
I'd just buy a drop out LS3 long block.
 

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Bad news :( i clayed the engine and smack a roo it does not clear intake or exhaust.

Next steps, pocket cut the pistons in place.

Method A, use an old LS3 head and an oversized valve, glue on abrasive paper and spin it till she hits max depth (0.125)

Method B, use a piston cut out fixture that will work in place.

i checked it without a gasket, my gasket is going to be 0.041 thick. I also checked it with the lifter at 0.050 preload and had about 0.095 intake clearance and 0.105 exhaust clearance. So i figure add 0.150 for the lifter pump up, and take off 0.041 for the head gasket and that's hitting by bout 0.015 on the intake - so piston cut of 0.125 would net me 0.110 of clearance on the intake side :). Not sure of the proper cutter diameter, i am using the 823 heads and stock intake valve.

never going to run Nitrous on this engine so i hope the 0.125 depth of cut is ok.
 

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Update.

The big 223/[email protected]" 0.610/0.624" lift cam on a 114 lsa w 6 degrees of overlap at 0.050" lift was just too close with milled 0.040" 823 heads, 0.041 gasket, and flat GTO LS2 pistons.

Lindy cutters used and i recommend them highly. Used a beat up donor head that was not milled at all. With a few layers of blue tape to protect the cylinders from metal cutting chips the issue was radial clearance at first. Outside edge of valve was hitting radial fly cut not bottom depth side. Then realized blue painters tape is 0.005" thick per slice snd we were using about four layers. Stack height was 0.020" and the donor head was 0.040" taller cause un-milled. So when we got rid of the tape and used shaving cream instead and btw that works far better, we found out there was a nice 60 thou of radial clearance. So the 0.040 millded heads w 0.041 gasket matched it perfectly. Lindy cutters were 0.070 oversided on diameter.

Cut 0.120" depth using a washer that we measured as a shim. Effective actual depth of cut considering stem shafts are not perfect and locking collar is not exactly true on the stem was 0.100".

0.041" Gaskets installed and heads bolted down w solid roller lifter and trend 7.325" pushrods (actual length 7.341") for 0.055" lifter preload .. btw we wanted 0.025" preload but hey.. the push rods turned out longer. I might swap them.

End result is 0.100 intake and 0.080" exhaust clearance.

Will it work?

Running 1211x behives w new upgraded trunion rockers from comp, trend 5/32 0.080" wall pushrods, stock solid valves, stock bottom end w 100k miles including original timing chain and oil still used.

Static compression ratio is 11.3:1 now.

Lifters are the ceramic ball ctsv-r similar to ls6 but better pistons w ceramic check ball i think.

Going to smooth the cut edges today to get rid of hot spots.

Thoughts appreciated.














Bad news <img src="http://www.ls1gto.com/forums/images/smilies/frown.gif" border="0" alt="" title="Frown" class="inlineimg" /> i clayed the engine and smack a roo it does not clear intake or exhaust.

Next steps, pocket cut the pistons in place.

Method A, use an old LS3 head and an oversized valve, glue on abrasive paper and spin it till she hits max depth (0.125)

Method B, use a piston cut out fixture that will work in place.

i checked it without a gasket, my gasket is going to be 0.041 thick. I also checked it with the lifter at 0.050 preload and had about 0.095 intake clearance and 0.105 exhaust clearance. So i figure add 0.150 for the lifter pump up, and take off 0.041 for the head gasket and that's hitting by bout 0.015 on the intake - so piston cut of 0.125 would net me 0.110 of clearance on the intake side <img src="http://www.ls1gto.com/forums/images/smilies/smile.gif" border="0" alt="" title="Smilie" class="inlineimg" />. Not sure of the proper cutter diameter, i am using the 823 heads and stock intake valve.

never going to run Nitrous on this engine so i hope the 0.125 depth of cut is ok.
 

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quick update - the gto is running great and smooth as silk. cut the pistson 120 (one accidentally to 185 deep!) so fingers crossed. got 28 degrees of timing, 0.85 lambda. 6800 rev. limiter. pulls hard all the way and breaths with ease.
 

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Sorry to revive an old thread but I've been asking around and haven't been getting the answers I need (even from machine shops)

I attached a screenshot of my build because I'm having trouble with figuring out compression ratios and what head gaskets I need.

I'm building a TBSS (same LS2 engine) with L92 heads that have been decked .030 to raise compression. The stock replacement pistons I bought are .020 shorter to account for decking the block / heads. With the cam I'm running, the heads milled what they are, and the piston height differential I'm having trouble figuring out how thick my head gaskets need to be to maintain stock compression. I don't plan on turbo/sc/nitrous down the road I'm looking for reliability with some fun built in. I also am worried about PTV clearance too. This is my first build and I don't know where to turn to put all this together. Thanks for your help in advance everyone.

https://imgur.com/a/KUgYcDI
 

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Sorry to revive an old thread but I've been asking around and haven't been getting the answers I need (even from machine shops)

I attached a screenshot of my build because I'm having trouble with figuring out compression ratios and what head gaskets I need.

I'm building a TBSS (same LS2 engine) with L92 heads that have been decked .030 to raise compression. The stock replacement pistons I bought are .020 shorter to account for decking the block / heads. With the cam I'm running, the heads milled what they are, and the piston height differential I'm having trouble figuring out how thick my head gaskets need to be to maintain stock compression. I don't plan on turbo/sc/nitrous down the road I'm looking for reliability with some fun built in. I also am worried about PTV clearance too. This is my first build and I don't know where to turn to put all this together. Thanks for your help in advance everyone.

https://imgur.com/a/KUgYcDI
After going through all of this go with the std. thickness head gasket and then check PTV using a lifter at max pump filled up with epoxy to represent worst case, bolt the head on without the gasket (you can add the thickness to your clay measurement). and if you are too close i.e. under about 0.100 to 0.120 then just buy the fly cutters and get an old junkyard head and its very easy to do the hardest part was what do we do about the shavings? its easy, shaving cream everything and then boom - shop vac that up all shavings are gone.

Also, make sure to get the right length pushrods at least check em. your goal is a normal amount of preload like .75 to 1.25 rocker turns seems good before all the play is gone.
 
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