KCS

iTrader: (20)

G Atsma

Right! This is why some heads with larger valves don't work as well in smaller bore engines. Bigger bores unshroud the valves, allowing more flow around the entire circumference of the valve.

big hammer

big hammer

Patron

Hammer may have not stated it just like that but the point is Correct. I've heard and read the Same thing else where. I know of a sponsor here that use to list that a Ls3 head flowed one number same port program on a .030 bore and it flowed like 20 more cfm on a 4.155 test bore. I just know BS when seen. We all know that a bigger bore helps with larger valves & shrounding. That ain't got NOTHING to do with a head flowing more with a larger test bore. I've seen the same 10-20 + cfm test with others on the web using a larger test bore. Common sense would dictate that if I have Straw in a cup that's pulling air the straw will only pull so much air the velocity may change but not the total amount of air moved. If the straw gets bigger more air. I just like to make things as simple as possible and not all the technical stuff. Technical stuff would lead one to think that a larger bore flows more air which it Doesn't.


BTW Hammer your right about the the TFS heads making HP: Funniest thing is I know of a Cathedral head making 900 hp @ 9000+rpm in a 403 Lq9 so what's this all about Cathedral heads not rev'ing. Funny! No matter the heads used, as Hammer would say: It just all has to work together.

G Atsma

Patron, I have YET to see a head run in a car without valves in it. The fact remains that IF the valve is too close to a cylinder wall it will be shrouded from flowing its max potential. You might be right in that a port (without valves) flows so much no matter the bore size but the fact remains that they don't run that way in real life.

Patron

I know and understand what your saying. Technically your correct......only one problem I and others run 2.20 valves in smaller bores could it be better? YES! Does it really hurt Hp and Tq production ......NO! Just ask ER or any other cylinder head guy Who's done this and ran the car and or dyno'ed it not just said what's known by all... Here's a point I've looked at with my own stuff in comparison. I know Mast makes a better Smaller bore Ls7 head with a 2.165 valve than my crappy stuff yet with a larger valve and honestly about the same size runner CSA not runner CC's. From .100 to point .800 lift I'm on the MAST as with honestly More everywhere .100 thru .800. With a larger valve that's closer to the cylinder. Could it be better yes will it kill HP.....Funny! If that's the case I and others would shrink the intake valve also. A smaller valve would be better yet if it stays at 2.20 it hurts Nothing in terms of HP and TQ. Now if 2 hp and 3 ft lbs of TQ if that,is all a smaller valve is worth count me out.

Patron

Eric you left HP and TQ on the table because of shrouded valves when you did the 435 Lq4 with 2.20 Ls7 valves & heads for the EMC.....LMAO! G Atsma if you think about it even with valves and bigger bore tested the runner can Only move so much CFM due to runner size. If anything Velocity will pick up if a larger test bore is used.
https://ls1tech.com/forums/parts-cla...rs-engine.html

Darth_V8r

iTrader: (4)

I don't think the engine gives two ***** if the port shape is cathedral, square, rectangle, round, octagon, or a triple helical rifle-port (insert link to "Tornado Brand" cylinder heads here...). it might give one ****, but not two of them. But when you get down to it, your intake selections ARE limited by port shape, and the intake effect on how an engine behaves is YUGE. LS3 heads IMO have the best variety of options for intake selection, so they make a great option for versatility.

With 5-cc difference between a 255 cathedral and a 260 TFS LS7 head, CSA is probably the important question. A longer port could have more volume but be narrower and flow slightly less, but generate better velocity. In a case like that the "larger" port could be better for torque and the "smaller" port might be better for top end power. On the large valve, small bore question -- I have seen people use very wide head gasket bores to somewhat deshroud the intake valve, but idk how effective that truly is. I could see it possibly helping some at lower lifts if I squint hard enough.

Hammer has dealt with many intake options out there. Would you rather have a fast midlength, fast short length, MSD, Fast 102 normal runner length, LS3 rod mod, Sniper? If you're not really sure what you want, LS3 heads give you the most options so you can just change cam and pick an intake that matches it right, and run with it.

KCS

iTrader: (20)

Tuskyz28

Is all flow benches the same? I don't think so...
It's really hard to compare 10 different heads on 6 different bore sizes on 5 different benches. Flow benches makes me think about rear wheel horsepower dynometers. Why ? Dynojet not really stingy. Mustang dyno is kinda stingy. Bluecat dyno is murder. A bluecat dyno like James short have will have a stroker 408 looking pitiful. Back to the point... people overlook alot when choosing heads such as valve size, valve angle, intake/exhaust relationship, valve weight, runner size.... just to name a few. Some guys thinks a bigger intake runner is always better and it's not. Just some food for thought.

Patron

Darth I've came to the point of it Really don't matter what port you have they all will make HP. And as Hammer would say: It just all has to work together: Cathedral, Ls3 or Ls7. Some are just better in different RPM points. The Ls3 does have the best intake selection of all Ls engines. I'd recommend just use the TFS heads, try what you have 1st and work from there. But with the OP's asking just 6800 peak rpm with some RWHP he's just a phone call away. Call CamMotion and done. The small stuff like intake choices we have all the results pick a RPM for HP and TQ then choose a intake accordingly.

Patron

KCS Eric told me straight from the hip don't Worry about the intake. Exhaust is the problem. The engine you speak of IDK but that seems correct. I'd worry more about intake choice than a shrouded valve. If I'm given a choice of a Ls3 head and Ls7 head with a larger 2.20 valve for a .030 to 4.080 bore it's Ls7 all day. Raised runner will do! Also Eric never said anything about the intake valves being shrouded that much never said anything about the intake @ all. A few guy's brought this up with the use of a 2.20 valve ls7 head on a small bore engine.

Also when Darin did the heads I asked only one thing make me a Bad AZZ small bore Ls7 that would outperform my FRH Ls3 heads he only shrunk the exhaust, if it were shrouding on the intake so Bad, I'd think he'd say something or recommend going to a smaller valve. And boy Oh boy did the Ls3 heads perform reference Flying's 418.

62nalide

iTrader: (2)

I'll be NA myself and ordered a set of Frankenstein's new LS7 10* heads 2.250/1.615 for my 427ci build.
They flow up to 442/281cfm

Patron

It must be nice......I've called and was told about these a little less than a yr ago. Chris took the best of all aspects of Ls heads. Raised runner like RHS Ls7 heads changed the valve angle, etc......I'm sure the runner CSA is around 3.2. Looks to be a great head just Needs Lift and RPM.

Also anyone that's been on here for some time knows that Tuskey Loves him some Cathedral heads and a manual. Was snooping around my bookmarks and lookie lookie. Just for you Tuskey. Now Hammer you'd better be on the lookout.....LOL you know how you and Tuskey go back and forth on heads. Anything's possible when done right big or small.......
https://www.lsxmag.com/features/six-...ng-lsx-camaro/

62nalide

iTrader: (2)

Yes they are getting closer, they are releasing 6 castings at once must be harder for a company that has grown pretty well. My build will take nearly 6 months to finish.

big hammer

G Atsma

I think you and I, along with most around here, would agree that there is NO head that is the greatest for every application. I would not put a TFS235 on a stock LS1, for example. The low end would be pretty soggy...

big hammer

Che70velle

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