Flow vs hp

General engine tech -- Drag Racing to Circle Track

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Frankshaft
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Re: Flow vs hp

Post by Frankshaft » Fri Oct 27, 2017 5:00 pm

2hp/cube would be a great number with that combo. 2.44/cube, ain't happening. Not to burst your bubble, but it's just not. It's hard enough with the very best heads available, and that's close to the limit at those cubes.

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Re: Flow vs hp

Post by treyrags » Fri Oct 27, 2017 5:15 pm

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.
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Re: Flow vs hp

Post by ptuomov » Fri Oct 27, 2017 6:08 pm

joe 90 wrote:
Fri Oct 27, 2017 4:59 pm
Steve.k wrote:
Thu Oct 26, 2017 7:18 pm
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.
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Re: Flow vs hp

Post by EngineTech1 » Fri Oct 27, 2017 6:30 pm

Steve.k wrote:
Fri Oct 27, 2017 3:22 pm
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.

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Re: Flow vs hp

Post by joe 90 » Fri Oct 27, 2017 8:17 pm

EngineTech1 wrote:
Fri Oct 27, 2017 6:30 pm


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.

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Re: Flow vs hp

Post by MadBill » Fri Oct 27, 2017 8:37 pm

joe 90 wrote:
Fri Oct 27, 2017 8:17 pm
..
There's zero relationship between the 2 CFMs.
So flow benches are a complete waste of money? :?
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Re: Flow vs hp

Post by EngineTech1 » Fri Oct 27, 2017 8:52 pm

joe 90 wrote:
Fri Oct 27, 2017 8:17 pm
EngineTech1 wrote:
Fri Oct 27, 2017 6:30 pm


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.

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Re: Flow vs hp

Post by bigjoe1 » Fri Oct 27, 2017 9:01 pm

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



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Re: Flow vs hp

Post by cab0154 » Fri Oct 27, 2017 10:22 pm

cstraub wrote:
Fri Oct 27, 2017 10:16 am
Steve.k wrote:
Thu Oct 26, 2017 7:18 pm
Is it possible to make 1100hp with fow numbers under 400cfm? No power adders.
Compression is your friend.
FACT!

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Re: Flow vs hp

Post by Steve.k » Fri Oct 27, 2017 10:24 pm

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?
Last edited by Steve.k on Fri Oct 27, 2017 10:26 pm, edited 1 time in total.

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Re: Flow vs hp

Post by cab0154 » Fri Oct 27, 2017 10:25 pm

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?

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Re: Flow vs hp

Post by cab0154 » Fri Oct 27, 2017 10:30 pm

joe 90 wrote:
Fri Oct 27, 2017 8:17 pm
EngineTech1 wrote:
Fri Oct 27, 2017 6:30 pm


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.
=D> wish we had a like button.

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Re: Flow vs hp

Post by pcnsd » Fri Oct 27, 2017 10:41 pm

joe 90 wrote:
Fri Oct 27, 2017 8:17 pm
EngineTech1 wrote:
Fri Oct 27, 2017 6:30 pm


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/

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Re: Flow vs hp

Post by EngineTech1 » Fri Oct 27, 2017 11:17 pm

cab0154 wrote:
Fri Oct 27, 2017 10:25 pm
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.

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Re: Flow vs hp

Post by Steve.k » Sat Oct 28, 2017 12:07 am

]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.

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