mrvedit

I have read the similar recent thread:
https://ls1tech.com/forums/generatio...l92s-6l-2.html
but it seems best to start my own.

I currently have an LS2 with 243 heads ported by Livernois. I am seeking opinions if L92 heads might make more power. And trying to figure out why an LS3 with 69ccm chambers has about the same compression ratio as an LS2 with 64ccm chambers.

Here is what I currently run:
Edelbrock 4150 EFI intake manifold with FAST throttle body
COMP 54-459-11 cam (231/239 with 113 LSA, .624 lift) with LS7 lifters
Patriot Extreme dual valve springs
243 heads ported by Livernois
Stock internals but with ARP bolts and 24 tooth reluctor; drive by cable

Looking at ported L92 heads, I fear the intake runner size will grow too much from the stock 260 ccm. Also L92 heads have a larger chamber than 243 heads which would reduce compression ratio.
Therefore, I am now considering the new Trick Flow LS3 CNC heads which have a 255 ccm intake runner and a steeper 12 degree valve angle for more PVC. I would have them milled to 64ccm chambers.

So here are my questions:

Q1 - Would unported L92 heads be an improvement over ported 243?
Q2 - Would ported L92 heads be better yet?
Q3 - Anyone have experience/opinons on the Trick Flow LS3 heads?

And my big question:

Can some please explain why a stock LS3 with 69ccm chambers has about the same compression ratio as an LS2 with 64ccm chambers. The LS3 only has 2% more displacement, but the chamber is 8% bigger.
I suspect this is why people who put a stock L92 head on their LS2 often don't see any improvement.

Thank you

Rise of the Phoenix

iTrader: (27)

What intake are you planning on running if you go the LS3 head route? Sticking with single plane? I would step up to the LS3 style heads. The TFS heads would be a really nice touch, but whatever you do, make sure to get a custom cam to optimize the combo.

mrvedit

Thank you for the quick reply and help.
Yes, I would use another 4150-style single-plane intake manifold for LS3 square heads. I have a 2" raised hood with plenty of space for a top-mount 14" air filter protected from engine heat.
I have experimented a lot with this engine/car.
I originally had an LS6 intake manifold; switching to the 4150 intake made a noticeable improvement and improved my ET by .3 and 3 MPH.
Last winter I switched from 1-3/4" headers to 1-7/8" headers and from a 1000 cfm throttle body to a 1400 cfm TB, but that made no improvement at all.
The engine (bought from a member here) originally came with a custom cam designed by Patrick G. The COMP cam is a bit milder and more streetable.

I don't yet understand why, but I know that cams are a bit different for square port heads versus cathedral heads. When the time comes I will read the threads on LS3 cams and select an appropriate one. My current PVC is only .045 which is one reason the TFS heads appeal to me.

lil john

Looking 4 a smaller runner cnc program LS3 264-267 cc runner : Darin Morgan /AI heads/WCCH/ but the smaller the better. TFS 255cc ls3 heads are better but it is hard 2 beat the factory in cost even with Cnc added.

As Phoenix stated custom cam 2 match what ever head obtained.

MX6.0

What kind of power is it putting down with the 243's?

mrvedit

Based on my best ET of 11.51 @121 (in cool temp last fall) and a weight of 3750, I estimate 525HP. It seems many people are doing better than that with milder cams.
I tune it with HP Tuners and wide band O2 sensors. Based on 14 track runs in the past two weeks, a PE of 1.16 and 27 degrees of advance give me the best trap speed. Based on my VE tables and logging everything, max torque is close to 6000 rpm.
I know that flat PE and flat advance (between 3200 and 7000) are not the best, but optimizing those would take a dyno tune. Livernois wants $800+ for a thorough dyno tune and that is too much for someone who is always experimenting.

low2001gmc

iTrader: (148)

Maybe i missed it but didnt see if your 243s are milled any. Ls3s with 69ccs dont make same compression as 243s with 64 65ccs. I milled my Ls3s .015 and used cometic .040 gaskets on my lq9 to achieve 11:1cr. That 231 239 is a proven cam in Ls3 headed combos but with plastic intakes and flycut pistons due to 624 lift. Advanced Induction Ls3 exhaust only porting option is best for Ls2 Ls3 build. Ls3 heads have lighter valves and easier on valvetrain stability especially with your cam duration and lift. TFS 255 heads are nice but you better have at least 3800 stall and 4.11s as you lose bottom end. My buddy lost bottom end in his 2010 Camaro 6.2 but gained mph on top end. The offset resulted in same 1/4 mile et with 3200 stall and 3.45 gears. He is stepping up to 4400 stall and 3.91s.

So in conclusion, id recommend flycutting your pistons or swapping to aftermarket pistons with notches to retain your proven cam with AI heads if on budget and running less than 3800 stall and 4.11s. TFS 255 prob wouldnt require flycutting or swapping pistons but best if youre willing to run at least a 3800 stall with 3.91 or 4.11s. AI heads are proven and prob best bang for buck. Martin at Tick has used them in several builds and im sure will vouch for them.

mrvedit

low2001gmc: Thank you! for the detailed info and suggestions. Very informative.

I don't know if my 243 are milled or not; I assume they are to keep the same chamber size. I will check with Livernois.
You mention the .040 gasket; what is the stock thickness and how much cc difference does this make? (Sorry to ask; I'm sure I could search this.)

I don't understand why you think the TFS 255 would loose bottom end compared to stock L92? Don't stock L92 have an even larger 260 ccm runner?
Or do your recommended AI heads have a smaller than 260 intake runner?

I currently have a Yank 3600 and 3.42 rear. I am considering a 3.73; it just takes me quite a few hours to rebuild a 10-bolt rear to get the gear pattern right.

I would appreciate a link or model # of a fly cutting tool. I would have done that when I last removed the heads, but could not quickly locate the tool.

low2001gmc

iTrader: (148)

Stock gasket thickness is .051 or .054. Have seen listed as both. I stated the TFS 255 on my buddys 2010 camaro ss 6.2 lost bottom end as a fact on his build which has more cubes. Yes TFS 255 has smaller than stock heads and AIs head intake of 260 but it flows alot more, which combined with 255 is not so great on 6.0 or 6.2 cubes. It is better suited for a stroker or high rpm 6.0 or 6.2 with bigger stall and lower gears.

With your cam, 3600 stall and 3.73s, i would say flycut pistons and go with AI Ls3 exhaust only ported heads.

I believe Spinmonster on Corvette Forum rents a flycutting tool. Ive never done it so i would prefer to contact Spinmonster or someone reputable to see if they have some ls2 or lq9 flat tops they could sell already flycut for Ls3 Valves specifically.

Or bore block to have fresh bore and go with aftermarket flat tops which will already be flycut for Ls3 heads specifically.

mrvedit

Just to followup...
After considering many options such as a stroker LS2 shortblock, I could not make up my mind and therefore decided to try selling my LS2 on Craigslist as either a complete engine, short block or piecemeal. Within 2 days I sold it as a minimal long block to replace a blown LS1.
Therefore, I will now buy a stroker LS3 shortblock and most likely TFS 255 heads and ask Martin Tick to spec out a custom cam for me.
Livernois Motorsports is very close to me, but I am also considering Texas Speed or Custom Engine Supply in Indiana.
If there are proven cams for this combo in the 10-16 degree overlap range, I am all ears.

dogsballs

Ls3 heads are very temprimental due to massive runner and valves. Rarely see much gain with cnc jobs as just kills them, unless you have big cubes. See good improvements with just milling

mrvedit

The Trickflow (TFS) heads have 255cc intake runners, which is less than the 260cc intake runner on a stock (non-CNC) L92 head. To me that is a big reason to get an aftermarket casting. More flow with a smaller intake runner is the ideal combination.
In contrast, the Livernois L92 CNC heads have 280cc intake runners.

Camaro99SS

iTrader: (4)

You may consider AI's porting option of just the exhaust ports but also the bowl areas and leaving the intake ports untouched.

But even at that their 267cc full porting option that touches the intake ports will still make the L92/LS3 head more efficient than stock. You'll just need to carefully cam around the big ports, but it's doable on a 6.0.

Jason

LivernoisMotorsports

iTrader: (1)

The L92's have a larger runner and support more total airflow.
Therefore have more hp potential.
As far as chamber size effecting compression ratio. It's easy to see what this does using a compression calculator from a good piston vendor like Ross or Diamond. The bore is larger on a LS3 vs LS2. Published numbers are just that as well as factoring + and - factory tolerance %.
Monday GM engine; deck height is.___"piston is in the hole .005"
Friday engine; deck height is .___" piston is out of hole .005"

The best way to calculate is to pour/measure and do the math.

A 12degree head is going to make more power n/a than a 15degree

You will see little to no improvement on a out of the box L92/LSA vs a ported Cathedral.
A ported L92/LSA will flow a bunch more than a ported cathedral. Then the question becomes is it too much runner/flow for your combo?

LivernoisMotorsports

iTrader: (1)

The L92's have a larger runner and support more total airflow.
Therefore have more hp potential.
As far as chamber size effecting compression ratio.
It's easy to see what this does using a compression calculator from a good piston vendor like Ross or Diamond.
The bore is larger on a LS3 vs LS2. Published numbers are just that as well as factoring + and - factory tolerance %.
Monday GM engine; deck height is.___"piston is in the hole .005"
Friday engine; deck height is .___" piston is out of hole .005"

The best way to calculate is to pour/measure and do the math.

A 12degree head is going to make more power n/a than a 15degree apples to apples valve/runner size considered

You will see little to no improvement on a out of the box L92/LSA vs a ported Cathedral.
A ported L92/LSA will flow a bunch more than a ported cathedral. Then the question becomes is it too much runner/flow for your combo? 400+ cubes the ported rec port takes the cake.

mrvedit

Livernois: Just today I ordered your LS3 418 stroker Pro Series short block - order # 10811. I will combine that with Trickflow LS3 255cc heads and a new Edelbrock 4150 intake for square ports. I'll likely ask Martin Tick for a custom cam.

When I originally posted, I couldn't decide which way to do and therefore tested selling my LS2 on CL as either a short block or complete engine. There was a lot of interest and I quickly sold a minimal long block to someone who needed a replacement for his blown LS1 in his track car.

It has been a very educational experience. The following thread was useful for all the part numbers needed to complete a short block and heads.:
https://ls1tech.com/forums/generatio...rs-prices.html

I'm basically done with this thread, but if anyone wants to "hijack" it, that is fine with me.

Sales@Tick

iTrader: (3)

Looking forward to helping you with your camshaft selection!

Sounds like a solid combination of parts!

BODUKE

Can't wait to see you run your z28 at Milan.

mrvedit

Martin: Wow, I'm surprised you read all these threads. I will contact you soon; Livernois wants 3+ weeks to build my short block.

Boduke: Guess you have seen me then. Have me met there? What do you run there?
Here are two runs by my daughter at Milan last summer:
Each about 11.65. Hope to get her in the 10's next summer.

BODUKE

[QUOTE=mrvedit;18545120]Martin: Wow, I'm surprised you read all these threads. I will contact you soon; Livernois wants 3+ weeks to build my short block.

Boduke: Guess you have seen me then. Have me met there? What do you run there?
Here are two runs by my daughter at Milan last summer:
Each about 11.65. Hope to get her in the 10's next summer.[/

Yes we have met there. I have been 11.28 @ 122. Your car will fly with the 418.