Flow vs hp

[treyrags]

I agree. That's close to the power per inch that Glidden was making with the small block in Pro Stock - but a much shorter stroke and lots of rpms.

[ptuomov]

Is it possible to make 1100hp with fow numbers under 400cfm? No power adders.

But 400 CFM is just an imaginary number which flows when there's a constant pressure of 28 inches water across it.


Increase the pressure and the flow goes up.


Flow goes up with a bigger cylinder and more revs.
It goes down with a smaller one and less revs.

+1

[EngineTech1]

Well heres the deal. As most of you notice im a huge fan of the iron cleveland. Im also going to receive soon a cgi version of the Trackboss block. Ive been wanting to put together a heavy hiiter iron motor. I've got a set of early prostock heads from Paul JENKINS of florida. I flowed the early heads and on our bench they were in 350cfm range. Since then I've done work on another set and have them sitting in the 368 range. Some guys claim to hit over 400 but I've never seen the sheets so who knows. Anyhow whats it going to take or is it possible. We would be able to hit close to 450 cubes.

The possibility of getting to 1100 hp NA with the combination you're talking about, well it's probably about zero. You're talking about almost 3 hp per cfm. which is, at least to my knowledge, better than NHRA Pro Stock. A strong number for a really well built small block in that mid 400 ci. range you're talking about with pretty efficient inline valve heads and a single 4bbl and sheet metal intake is about 2.2- 2.3 hp/cfm. My reference is a little bit dated so more advanced valvetrain may slightly improve that but by hundredths, not tenths.
Anything north of 2 hp/cfm is a pretty good engine and in the 2.2 range and up is a pretty serious race engine.

[user-23911]

The possibility of getting to 1100 hp NA with the combination you're talking about, well it's probably about zero. You're talking about almost 3 hp per cfm.

no it's not.


CFM which an engine consumes as it runs is completely different from the imaginary CFM which it flows on a flowbench at 28 inches of water.

There's zero relationship between the 2 CFMs.

[MadBill]

..
There's zero relationship between the 2 CFMs.

So flow benches are a complete waste of money?

[EngineTech1]

The possibility of getting to 1100 hp NA with the combination you're talking about, well it's probably about zero. You're talking about almost 3 hp per cfm.

no it's not.


CFM which an engine consumes as it runs is completely different from the imaginary CFM which it flows on a flowbench at 28 inches of water.

There's zero relationship between the 2 CFMs.

That’s about the most absurd thing I’ve seen posted on this forum. Why exactly do you think people who develop cylinder heads use a flow bench? There’s a very real correlation between the two.

[bigjoe1]

I agree ! Every time I have made an increase to the intake flow, the engine will make more power



JOE SHERMAN RACING

[cab0154]

Is it possible to make 1100hp with fow numbers under 400cfm? No power adders.

Compression is your friend.

FACT!

[Steve.k]

Well this is exactly wonder im wondering. I knew the prostock guys were high up there so was thinking maybe possible. I thought Glidden and them were close to 800-850 on way less cubes.So then the next question ! Anyone here get the heads over 400?

[cab0154]

rather than simple static dry flow how about a discussion of target cross section (with a target flow per sq inch of cross section/airspeed), displacement, piston speed, lobe area and compression needed to get the job done?

[cab0154]

The possibility of getting to 1100 hp NA with the combination you're talking about, well it's probably about zero. You're talking about almost 3 hp per cfm.

no it's not.


CFM which an engine consumes as it runs is completely different from the imaginary CFM which it flows on a flowbench at 28 inches of water.

There's zero relationship between the 2 CFMs.

wish we had a like button.

[pcnsd]

The possibility of getting to 1100 hp NA with the combination you're talking about, well it's probably about zero. You're talking about almost 3 hp per cfm.

no it's not.


CFM which an engine consumes as it runs is completely different from the imaginary CFM which it flows on a flowbench at 28 inches of water.

There's zero relationship between the 2 CFMs.

Joe,
I think it depends on how you slice your time from m/sec to m/sec. A flow bench appears at least to me to correlate reasonably well to the intake pumping cycle. Ramming and overlap perhaps not so much. I have seen progress from flowbench development work. I don't think it is a fluke.

From Darin Morgan;
http://darinmorgan.net/category/techarticles/

[EngineTech1]

rather than simple static dry flow how about a discussion of target cross section (with a target flow per sq inch of cross section/airspeed), displacement, piston speed, lobe area and compression needed to get the job done?

Talk about a can of worms. When the dude got specific he has heads that flow less than 370 cfm and wants to build close to a 450 cid. V8 to make 1100 hp. Obviously those things you mentioned are the types of considerations that go into designing a port for a given application but based on this guys statements this isn’t a highly developed cylinder head.

Best case scenario, if you have a very efficient cylinder head with the right csa, taper, valve size, runner lengths, plenum volume, etc, etc, it’s still not only suboptimal but pretty unlikely to be able to make that 1100 hp level.

I’ve done piles of SBF heads for NA engines for circle track and drag race and 425+ cfm heads are what it took to make 980+ hp on a 440 cid. engine with a single dominator on a sheet metal intake. Dual carbs would have eclipsed the 1000 mark and valvetrain can be done a little better now but things haven’t changed that much.

370-380 cfm heads on bad ass small blocks can get you in that 800-850 hp range generally speaking with the right combination but most builders aren’t going to pick a 370 cfm set of heads for an 1100 hp NA small block build.

[Steve.k]

]370-380 cfm heads on bad ass small blocks can get you in that 800-850 hp range generally speaking with the right combination but most builders aren’t going to pick a 370 cfm set of heads for an 1100 hp NA small block build.

[q This is more typically where i thought the heads would go. However i had seen talk of more away from this site. Thanks for imput everyone.

[andyf]

..
There's zero relationship between the 2 CFMs.

So flow benches are a complete waste of money?

Not a complete waste of money but they do not predict the future. Kaase had a nice article a while back on Hemi vs. Wedge heads. It is worth a read or two. Basically his two heads flow roughly the same on the flow bench but the Hemi head makes a lot more power on an engine. So the flow number tells you part of the story, but it doesn't tell you the whole story. There is a quality of the flow which is important. Also the location of the flow, and the velocity of the flow. I'm sure there are other things such as turbulence and swirl and who knows what else.