VAP

Thanks for all the responses gentlemen and I would like to point out that in my original question I did ask could someone please tell me the best flow figures from .100 TO!!!!! .700" and as I suspected no one did that ! and that's why I asked for peak flow figures ( at least ). With at least these figures @28" you go E.G 350 cfm mulptilied by .257 multiplied by 8 = 719 hp Potential with a 100% vol. eff. Then based on the port volume and cross sectional area of the inlet runner you can then work out what cubes you'll need to use to make the HP desired at a chosen RPM. What rpm the heads are good for and then work out what cam will best get the job done at the Vol. Eff. you expect to achieve based on compression ratio, fuel being used, cam type etc. etc. I have been using this simple formula for a decade and it works well.
Anyhow I really just needed to know how good these heads can be ported to (benchmark) as i got an LS1 head to go 290 cfm @ 28" @ .650" on my first attempt without the factory turbulance which i thought was very good considering i didn't enlarge the runner at all. Based on how good the genuine LS1-LS6 ported heads flow DO YOU THINK THERE WILL EVER BE A DEMAND FOR AN AFTERMARKET GEN III head ?I've yet to flow a std ls6 head but based on what I've seen of the ls1 heads they are simply put awsome for a mass produced factory cylinder head. Thanks once again for the responses.

The Derek H

My new set flowed 350 cfm at .700 on the intake. I'm actually running that much lift. I don't remember the specs on the intake. If I have time to stop by Thunder today they have a copy of the flow chart and I'll try to post the numbers at each lift increment for both the intake and exhaust.

I have 2.10/1.60 valves in 6.0L heads.

HP-GURU

So with all those HP formula's based on peak head flow.

Say you had a head that did:

.200" 150cfm
.300" 220cfm
.400" 265cfm
.500" 300cfm
.600" 330cfm
.700" 345cfm

vs one that did:

.200" 200cfm
.300" 240cfm
.400" 280cfm
.500" 325cfm
.600" 330cfm
.700" 330cfm

Which one wins in power production? I think the 2nd one does, so those formula's that predict power based on peak flow numbers can't be all that right, you have so many other pieces to the equation.

hondakiller

iTrader: (3)

a guy i know who works for tea said the best he saw from ls1 heads was 315/255 at 600 lift with slightly larger intake valves and stock size exhaust valves. he didnt say how much larger intake valves though.

SStrokerAce

iTrader: (2)

"With at least these figures @28" you go E.G 350 cfm mulptilied by .257 multiplied by 8 = 719 hp Potential with a 100% vol. eff."

I really don't like this as a way to estimate engine potential or head potential. So we have 330 cfm heads out there (Agostino just had an article where they said this was max flow) so that means the 422 cu in is good for 680+hp? NO! The intake manifolds are a huge problem here to get that kind of power, on top of that the 80mm T/B will not allow enough flow through it to get that HP. You need a 100mm or larger T/B to get enough flow to not restrict the heads.

The Volumetric Efficiency on a well built engine will be in excess of 100, so a 355 could act like a 383 or 400 at ceratin RPM's. I really hate to see this equation used because it means ****. The whole system means much more. True the heads are the limit to HP but on the LS1 we are running into different problems and headflow is the least of them. Tuning the header length/diameter and intake manifold now is much more important. I only say this because a optimized LS1 with 290 cfm heads and 330cfm heads is not going to be a huge gain, in fact it will probably be under 20hp. IF you plug 40+cfm into that formula your going to find more than that 20HP. That is why I say that the formula is useless.

BTW how many LS1's have you heard of that can get 720hp? ZERO, because the intake system cannot do that.

How about we figure out how big the ports are with certain CFM's Agostinos 330cfm heads are 235cc runners, that can give you an easy port velocity, I would rather have 215cc runners with 330cfm, the extra torque will win races! BTW AFR has old school chevy small block heads that are 215cc's with 320cfm flow, those on a 365 cu in engine are good for 600hp at 6000 rpm. More if you spin it up to 8000rpm. On that point why is there not a formula that will give you max torque for a cfm and a displacement that would be much more useable. **** a F1 engine has more HP that a Winston Cup engine but TQ per liter is actually equal in the two engines.

Hell a LS6 at 400 ft lbs and 5.7L is only 70 ft lbs per liter compared to the M3 engine which has 265 ft lbs and 3.2L = 82 ft lbs per L. And the BMW F1 eninge is the strongest out there. (BTW the B16A engine in the Civic Si only has 69 ft lbs per liter. TAKE THAT RICERS!)

LS1derfull

When you look at velocity with heads, you have to realize flow increases with larger volume can equate to as high or higher velocity than smaller less flowing heads.You have to look at displacement and rpm range your targeted increases are aimed at. A 422 Ls1 can have too much velocity and that would cost it HP potential.
Ive seen motors make very high Hp for the amount of restriction a carb or throttle body puts on them also. Remember all the posts you see on here are rear wheel hp, and i wouldnt be surprised if somebody made 700+ horsepower with a LS6 intake,
at the flywheel.

SStrokerAce

iTrader: (2)

Yeah I understand the bigger cube means the port velocity will go up. I was just pointing out that we are not up to the level were the old small block heads were yet. We are starting off with a better starting point. I've heard of 630hp at the flywheel on a N/A LS1 so far. Trust me you can find 20-30hp in a T/B on a engine that strong.

I still like to talk about TQ per L because it's not about a bottom end that can handle 8000rpm's it's all about heads and tuning.

Bret

HP-GURU

CC's aren't CC's between different heads. For example the old SBC heads where a bit longer than the ford heads so 200CC SBC is smaller than 200CC SBF.

LS1derfull

Thats true and one of the trick things about LS1 port is its big but has excellent air speed, because port width is narrow, but tall to make room for hi flow,the bowl makes up a lot of the port volume which doesnt hurt port velocity and gives air decent room to bend around valve and seat area.

WeatherGuy

Since this thread has brought up head flow, intake manifold restrictions, 422s, and torque per liter, I have to jump in.

Some typical head flow numbers and the effects of intake manifolds on them are found in https://ls1tech.com/ubb/cgi-bin/ulti...c&f=1&t=000464
The info is about halfway down the first page of the post.

Regarding peak flow numbers: I was originally a little upset with the flow numbers on the LS6 heads I have on my 422, because they were "only" flowing about 316 CFM at 0.600. However, I became much happier when I looked at the overall flow in the midlift regions, which were still 300 CFM at 0.500 and and 200 CFM at 0.275. This profile was good enough for me to be around 82-83 Ft-lbs/liter and about 84 HP/liter on a very streetable cam. However . . .

I don't think I am getting all of the power out of these cylinder heads that I could, so getting heads that flowed even better would be unlikely to get me any gains. Why? As has already been pointed out, the intakes are the big restriction (see link above). Until we get this solved somewhat, I am not sure if we are going to be able to flow much >300 CFM NA. This then means that the crucial thing on LS1/6 engines for realizing power and torque is going to be the total effecive flow under the intake curve (intake lobe), normalized and lagged appropriately by cylinder pressure deficits. In other words, those mid-range numbers become damn important.

LS1derfull

I dont know if i agree about lS6 manifold holding back LS1 motors power, John lingenfelter had built some trick LS1 intake with twin throttle bodies, and it wasnt worth that much power over a LS6 piece. If your building a big motor and are concerned about upper rpm breathing than why not just raise compression ratio way up? That would extend power where V.E. falls off.

Plan B

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by SStrokerAce:
<strong>How about we figure out how big the ports are with certain CFM's Agostinos 330cfm heads are 235cc runners, that can give you an easy port velocity, I would rather have 215cc runners with 330cfm, the extra torque will win races! BTW AFR has old school chevy small block heads that are 215cc's with 320cfm flow, those on a 365 cu in engine are good for 600hp at 6000 rpm. More if you spin it up to 8000rpm. On that point why is there not a formula that will give you max torque for a cfm and a displacement that would be much more useable. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">That’s all very nice, but why would you be concerned with old school intake runner CC’s when the LS1 intake runner length is so long? Take a good hard look at ARE and if they are making the numbers with this volume then simply use it as a benchmark. Please, don’t concern yourself with old school heads. After all, the cylinder head intake port should only be treated as a receptacle for the intake manifold. ie; It just continues the flow and finally gets it through the valve. Relative CC’s to other engines???? Nah! <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Oh and as for John lingenfelter building some trick LS1 intake with twin throttle bodies, and it wasnt worth that much power over a LS6 piece....

Thats his problem.

<small>[ April 14, 2002, 06:57 AM: Message edited by: Plan B ]</small>

LS1derfull

Plan B i remember you your the sicko with the Gorgeous Exotic Space Shuttle technology LS1 intake! Anyway i think as far as intake port being a receptacle for manifold remember , manifold only flows dry air and int. port has to suspend and manage fuel droplets, also port has to negotiate turn past valve and set up cylinder helixes for fast efficient filling. These challenges make int. port a seperate entity in my opinion to manifold . <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

VAP

Guys I 100% agree with what you are saying about peak figures not being of the ultimate importance for a street car ,but once again I do have to point out that i did state that once you have your flow figures and cross sectional areas or port volumes you can work out what cubes you need to build the motor to achieve the power required at the vol. eff. AND at the rpm you want it to happen by. Rough EG a 235cc head that flows 300 cfm will make 616 hp with 100 % V.E BUT you will either need to build a big cube motor or rev the **** out of it !!!! Once again a head that flows 300 cfm with 200 cc port volume will make 616hp at 100%vol eff. but will do it a lot easier and not need to be a big motor and revved hard. The smaller the port volume at the same cfm means that you will make the power easier. Or moreso get a better V.E easier. BUT if you are chasing 700 hp you will not get this with a head that flows ****, but is great in relation to its port volume versus flow. Peak flow numbers ARE important if you are trying to make big power.I recently engine dynoed an engine to test and confirm this. The engines was a 400 sbc with cast iron heads with small solid roller cam for jetsprint racing. One set of heads had 216cc port volume and the other had 226 cc port volume. The larger 226 port volume heads only flowed about 7 cfm more up above .600".( NOTE THAT THERE WAS AN INCREASE ON PORT VOLUME OF 4.6 % AND ONLY A VERY SMALL INCREASE IN FLOW ) The larger heads made the same ft/lbs but did make about 12hp more up top ,( HELD ONTO THE TORQUE BETTER ) but admittedly it all happened about 200 rpm higher up. Even though the smaller port volume made great power and torque the larger did make more H.P.
SO FOR A "STREET" CAR THIS IS bad BUT FOR COMPETITION PURPOSES this means you just have to rev it harder.POWER wins races not driveabilty.
An F1 car don't drive nice!
A prostock car don't drive nice !
A street car drives nice.
Which would you prefer to RACE ?

In regards to the other response about the manifold not flowing or the throttle body etc. being a restriction - TRUE but **** dude you ain't gunner make 700 hp NA with a 226 deg @ .050" camshaft either !!! Companies will introduce better components for these engines as they feel there is a demand for them.

I'm not attempting "at this stage" to make 700 hp normally aspirated ,I'm just trying to find out what the shops in the USA "CLAIM" they can get out of the heads !!!!!!!!!!!!

350 Cfm out of an ls6 head ????? I'd like to see that. What "HAPPY" flow bench were those figures taken from ?????? Wonder what bore size the heads were flowed on ????? Please ask this for me DEREKHLS1Freak -

Thanks once again gentlemen for the input.

lafnatu

wow, you guys make me feel real dumb

VAP

Can anybody list some flow figures of well ported heads from .100 to .700" @ 28" - what valve sizes and on what bore size - with or without manifold. Anyone please ! ls1deerful ?

One Monkey

Best flowing LS1....... I know of is. 340CFM. Best flowing LS6 350 CFM.
Bouth by the same guy. Instructor at SAM Casey.
I don't have the flow #s but here is one mines.
this head is one of My favorit
100 .97
200 .199CFM
300 .248CFM
350 .267CFM
400 .280CFM
450 .300CFM
500 .305CFM
550 .311CFM
600 .320CFM
700 .320CFM
2.055.valve.
the head got tubulent and it took some time but I ended up leaving as it is.. because I preffered it too level off and not pull back. the cam and RPM it was going to run at requied good High lift flow.

For the valve size and port size it is a very good flowing head I have heard claims of better heads than this. (Have not seen any but heard claims) There are heads that flow higher #s but I like this one out of all the LS1 head I have work with because 200CFM at .200 is simply bad ***. It Makes over 500RWHP on a 409Ci motor. With 10.5 compression.

as for the Intakes. there are cars making close too 700Hp. we will be Dynoing some LS1 motors on a engine dyno a about 3 weeks. The dynos # will be in one of the mags. but we will get to mess with some cam Timing and fuel on the Dyno wich will make things alot easer and 700Hp should be there some where.

PS I do agree however that there alot too gain from a larger Intake.

Racer7088 (Eric) have seen this head on the flow bench flow him self.

<small>[ April 22, 2002, 07:27 PM: Message edited by: One Monkey ]</small>

BADZ

iTrader: (5)

GTP makes a great set of heads....