Lexicon

Hello All,

I am getting ready to tear into the 2007 LS2. The rear diff is done. The motor has a fast 102 and 2009 Z06 bimode. I am keeping the stock bottom end. Will do cam and HB.

I need to get the compression ratio down before I add the A&A. Are Trickflow 235s the ticket. I am sticking with cathedral port heads. If not the TF 235s then what?

realcanuk

Need to know the chamber size to know the effect on compression ratio.

Blackonblacksls

243 have a chamber in the mid 60s.

You can get tfs with a 70 chamber..

Will lower the comp a little over half a point.

Tfs always seem to perform well.

Lexicon

Exactly. Tf 225s are what most people put on but that keeps the chamber the same. 235s are too big for an ls2 with a 6 in bore. They have bigger chambers, 70cc. With FI i expect they are the best option but I thought the FI group would have determined the best heads to use if you are doing it all.

I need a cathedral port head with bigger chambers. I could have the stock heads worked over (CNC and all new parts) but the cost is only a bit less than a set of TFs. If I am wrong, point me to the vendor.

Who is upgrading or taking their car back to stock? I need an A&A kit, heads and cam.

realcanuk

I am using Edelbrock 245's from WCCH. They are fantastic for my application but mine have 64cc chambers, which wont decrease compression. I think they are also available with 70 cc. Optimum size will depend on the power level.

winters97gt

I'm confused on this thread. Why do need to swap the heads from 243's?

Lexicon

I want better flow on the exhaust and to bring the CR down a bit for more boost when supercharging.

Either the stock heads need to be rebuilt with CNC, double spring kit, valves, etc or get an aftermarket set of cathedral port (ls2) heads. I think the 70cc chamber Trickflow 235s are the way to go but there must be sombody who has put heads, cam, and an A&A kit on an ls2.

I am looking for advice on the heads.

winters97gt

Plenty of guys pushing 700-800rwhp out of the stock head LS2's with proper fueling and living fine for years. I think you're just waiting money, honestly.

inspector12

Yeah I'll back Mark up on this, and say ppl are running on the limit of what a stock bottom end will take with the stock heads. Bill (5 liter eater) made 760rwhp I think on his stock LS2 with cam, headers and small blower setup. He ran that for a few years and I ended up buying the stock motor running fine etc... I do know what your saying about lowering the CR and I would usually back up the OP on that for safety, but I think you should save your money at this point. JMO. GL!

neverstop

I made 760whp pretty easily with 243 heads on stroked Ls2 with a D1SC and a horrific tune from a guy who has no idea what he was doing.

Stock 243 heads will easily make more than enough power to nuke your stock bottom end. Money better spent elsewhere imo, like meth setup, clutch, tires, etc

Lexicon

Thanks for the advice. I found that per TF you cannot run the 235s on a 4" bore. They are not an option. To have AI redo my 243s it is $2k. They offer TF 225s CNC to 230 for $2.4k and with cam and pushrods $2.9k. The thing you can't get with the 230s is a big combustion chamber.

This is for insurance. I am not comfortable running single springs with weak valves and non captured rocker bearing with FI.

I guess the 243s are added to my parts for sale pile.

winters97gt

Good luck! You should get a couple hundred bucks for those 243's. It's going to be unfortunate if something lets go and you trash those heads.


You'd be way better off saving that 2 grand toward building a shortblock in the future or saving it for a rainy day fund. If that motor grenades with those new heads, then you're out quite a bit. Some of us have been there and done that, more than once. You're not treading down a new path that hundreds of here haven't been down. 243 or even the 241 heads on LS1's, nor LS3 heads are the issue. Not sure where you're getting your info from, but good luck.

schpenxel

Agree 100%.

inspector12

Well your wrong about being able to run the 235's on a 4" bore. Done that multiple times. But if your going to go smaller I'd take a look at the AFR's Ive ran both and both are good. I just never lifted my AFR's it could have been luck, but I haven't found many ppl who had lifted them. GL!g

winters97gt

Exactly, you drug people with all your builds on your your LSX builds when I was young buck hanging out around jayson at MTI since I'm younger. You helped me out, you've been there and done it. The only difference we have had, and nothing personal since you helped Double pin my old crank, is just clutch opinions.

That's why I highly respect your input on threads, I've been at your shop seen your shop and knowledge first hand.

So back to the OP. Those 243 heads can make serious power both FI and NA. A destrocked LS7 that revs to the moon? Nah, I'll take a 800hp car that runs down the track with stock gearing, suspension, street drag radials, and drop the targa top for 800 mile drive from the track and weekend cruise.

nullpointer

I have AI's 226 package on my 243s and easily made 650s on a mustang dyno, 740s on a dynojet. Save the cash for the short block, eventually you will need it

newvetteguy9

i'm very confused by the thread but i'll post my .02. 243s are great heads I make over 800 (on e85) 750 on pump, with stock 243s and stock block...... stock intake manifold with a cam. Maybe my car is a freak and has held together well. For all the guys going to tell me it's a ticking time bomb thanks I'm aware and already have a 406 (.20 over instead of .30 not a typo) ready to go in.

Advice from me? ditch that fast when going FI. I can send you pictures of failed FAST under boost. I've seen them first hand this isn't "i know a guy" talk. Sell your fast put your stock one back on take that money and put it back into your car.

You don't NEED to lower compression to make power out of an LS2 by any means. infact my vote is to NOT lower compression as off boost it will be a dog depending on the cam.

I know and realize my way isn't the only right way or may not even be right at all for some. Just speaking from what i've done on my own car.

with that being said the expensive heads will work great! I'm putting a set of aftermarket heads on the 406. but for a stock motor it wasn't worth it for me. 0 bang for the buck. Only updates to my 243s are what was needed for my cam. no cnc work no porting.

Unreal

Skip heads, put money into clutch, diff, or just save for a motor. No need to waste money.

Just throw some decent springs on the heads.

lt1z

I agree that if you haven't already done other upgrades to put the power down that I would not do heads first. However, I don't think they are a waste of money. Build the most efficient N/A motor first and then add boost. I would rather make 800whp @ 13 psi then 16 psi.

schpenxel

Why?