Godzillaz28

I'm building a Lsx 468 4.250 stroke 4.185 bore and it's going to be around 13;1 on e85 hydraulic roller. Are my the 245 heads to small? They have the n20 port from but.

redtan

iTrader: (5)

Personally I'd go with some variation of the LS7 head at this point, but those should be allright. That or the MMS 255s.

slogo

I'm with redtan

Here's a little something to read.

http://www.hotrod.com/how-to/engine/...top-ls7-heads/

DavidBoren

I would imagine that the trick flow 245's can be made to perform quite well for this application. I definitely wouldn't be in a hurry to get rid of them.

Here's a good article comparing similar rectangular vs cathedral port heads on the same shortblock, using two cams (tests both heads with both cams to be "fair").
http://www.superchevy.com/how-to/ght...-head-to-head/

But you definitely can't go wrong with some mamo-fied mms/afr225's.

redtan

iTrader: (5)

Compared to the rectangular port heads (LS3/LSA) I agree stick with the cathedrals. However square port LS7s are a whole nother animal and on a big bore/big stroke like that I'd like to see a 400cfm+ LS7 head on there.

Or some TEATFS 265s

http://www.totalengineairflow.com/pr...ylinder-heads/

Godzillaz28

The 265 are the tfs 245 ported by tea. Their awesome heads I just want 2nd opinion

Exidous

iTrader: (11)

Aside from monstrous CI, what are your goals for the motor. A max effort would certainly warrant bigger heads but those 254's could make for insane low to mid tq. Max effort would also warrant a Low Lash Solid Roller setup.

Godzillaz28

I had a 427 lsx when I bought these heads if I planned on going this route from the beginning I would have bought some LS7 style heads. I got told its gona choke that much ci. And it would run better on a 454. But with that much stroke I figured itd be smart to go to a bigger bore over a 4.125 bore

Tuskyz28

I would call someone who knows cylinder heads and gives a honest answer to each band of heads. Brian Tooley will do just that. Give him a call.

KCS

iTrader: (20)

SAM used almost stock LS7 heads and a really little cam with a ported factory intake manifold on their 500ci LS2. It made north of 700hp all motor on the engine dyno. Over 900hp with nitrous.

I would go with LS7 heads if I were you.

Brian Tooley Racing

iTrader: (13)

In back to back testing on a 4.125" x 4.125" 440 cubic inch engine on the TFS Superflow engine dyno, the TFS 235 heads made 20 hp more than stock LS7 heads, and the 245's will make even more power.

If the engine is hydraulic roller and sub 7000 rpm I would run them all day long...

Here's some making over 700 hp on my 454: http://www.superchevy.com/how-to/pro...stroker-build/

redtan

iTrader: (5)

I don't think anyone here that mentioned the "LS7" heads actually meant a stock unit as it came from GM. Myself I suggested a variation of the LS7, whether heavily massaged by a well known porter or something along the line of MAST LS7s. On such a setup those will surely run away from even the 245s (except maybe down low but I doubt this guy is building this engine to be racing at 3000rpm)

Godzillaz28

Grudge,track,"streetcar"

redtan

iTrader: (5)

http://www.mastmotorsports.com/view.php?id=518&c=20&s=4 would be my choice.

Spendy, but you're already dropping a **** load of money on that setup...no sense in skimping out on arguably the most important piece.

Godzillaz28

I already have the tfs245s. From my 427 build. I really like that brodix LS7 273. that's what I would of bought if I was building this motor from the start

Brian Tooley Racing

iTrader: (13)

I love big heads, I have LS7 heads on one of my street cars.

However the dyno doesn't lie, efficiency makes more power than just being BIG does. How else would a set of 345 cfm heads make 20 more horsepower than a set of 370 cfm heads?

Reference the article by Richard Holdener who pointed out that the Mast cathedral port heads made just as much power as the square port heads. Did you see his explanation about coefficient of discharge? Do you know where he got that information from? You're welcome...

Don't fall into the trap of thinking that bigger flow numbers equal more power on a hydraulic roller setup running 7500 rpm or less.

Another statistic to reference here, NMCA Real Street class, fastest MPH in 2015 was 180 MPH in the 1/4 mile, accomplished with TFS 245 heads and a hydraulic roller cam, out running LOTS of LS7 style heads with solid roller camshafts. Don't be a sheeple, think for yourself...

Godzillaz28

Hey brian it's chris lol we just talked about this earlier. So even though it's 40 more ci still a good head to use with hydraulic roller and around 7-7500 rpm?

Tuskyz28

Bigger is not always better is all I'm go say. I think there is a such thing as too much head on a motor.
Example and truth .... it's so many guys on here stuck on the LS3 head. Thats why i got some now on my motor in my camaro. They have huge ports for a great price... so they tend to be hard to beat for the money.
Good example here with real world results here on board.
402ci 11.1:0 comp,242 250 cam,ported l92's,vic jr intake, 6 speed car full weight. Car went high 10s on motor.
Then the owner did a head swap to a smaller 235 tfs head with a fast intake with a equally size cathedral head spec cam. Not only was the car quicker in the 1/4 mile with a worst 60ft due to spinning but it was more drivable on the street. The big huge heads just don't seem to get down the track as fast as a cathedral head.
Most guys here on board just look and the huge intake number and valve size and totally forget about velocity/efficiently of a cylinder head.

Rise of the Phoenix

iTrader: (27)

Post of the day right here. Hell, maybe the post of the year. OP, do yourself a favor and listen to this guy.

Godzillaz28

Did you read all of it???? I HAVE THE TFS245 I LOVE THEM... I'm asking if their to small for a 468 because if so I'll build a 454... And there is such thing of to small of a head just because there big for a 402 and work great on it.