BC

Can anyone comment on these posted head flow numbers compared to the 928 32V heads?

http://www.enginelabs.com/engine-tec...he-long-block/

IcemanG17

I recall Devek quoting flow numbers for 32V in their catalog.......I think around 265cfm intake and up to 330cfm with the ported big valve heads.....similar to what the Ford engine is flowing, BUT at lower lift.....

200hp/L is pretty easy to achieve with boost....

FBIII

New 4 V head flow figures

FBIII

Sorry thought I was pasting something to click on but it doesn't work. The above search is an extensive post by Slate blue.

BC

Where is that?

Mark Anderson

Here is the info on the heads that Kelly Moss did

lift intake port velocity exhaust port velocity

100 102.8 76.4 94.8 131
200 204.3 151.8 173.9 207
300 288.2 214.1 236.2 281
400 330.5 245.6 247 294
500 350.4 260.3 250 298
600 354.2 263.2 252.4 301


stock head was 274 cfm at .500
all measurements done at 28"

GregBBRD

Seems like ever data point I use is lower than everyone else claims....

Either I live inside the Bermuda Triangle...or others have "very optimistic" measuring tools.

atb

Ah ha! That would explain this map that I saw recently:

ptuomov

Some random comments, all based on theory and with almost no practical experience:

I think that one would first have to decide the valve size before evaluating head flow. Once one has picked the valve size, then one can start talking about port shape, cross-sectional areas, and CFM and air speed goals for that valve size. The combination of the camshaft and head numbers (CFM and air speed) then either match or don't match the target volumetric efficiency, displacement, and rpm. This will lead to iterating again. I have found PipeMax to be an economical and fast software for doing quick ballpark iterations like that, but I digress...

I guess that to the extent I have a point (and I often don't) it's that it's hard to evaluate heads in isolation, other than what kind of CFM and air speed one gets for a given valve size. I am under the impression (no knowledge claimed) that the standard S4/GT/GTS heads of any casting revision with nothing done flow very well for their valve size.

With respect to the article you linked to, I think it's a lot of marketing hot air. The flow numbers quoted are at 0.650" lift and I don't immediately understand how you could get modular Ford cam to lift above 0.500". Furthermore, I don't understand how a 5.0L Coyote could take advantage of those CFM numbers at 7500 rpm even if the cam could lift to 0.650". Color me skeptical of whether those flow number targets were set by the engineering or marketing department.

BC

Its for a Coyote that will get two turbos - right up your alley. They are shooting for 1000hp, but building it.... IMO, with some old info. They are doing "low compression" on the bottom end because its 1970 and we can't control an ECU properly to get det-free power I guess. But thats just me.

Its a Four valve head. Ours is a four valve head. They have two cams. We have 2 cams.

They are actually reducing the phase swing on the VVT to allow for the bigger cam, which is an interesting prospect.

SG was very far ahead of his time in trying to get the variocam onto a 928 motor. Cam phasing is even on chevy truck V8s now.

The lift is no where near 650. Its at 490/450 I/E.

What they are doing with those 5L Coyote engines is really good though.

slate blue

I was advised of this post and thought I might add something to it, as most would know I have not done anything regarding my 928 engine projects due to my health, so unfortunately I cannot give any hard real world dyno data. I am still getting surgery so when that is over hopefully that will change.

So what I have is research, research that has been a joint effort with some clever minds in the racing industry. I also have a reasonable knowledge of racing engines myself and can say that the 928 heads can be made to flow a lot of air.

Two specialists I consulted, one in head porting the other in induction systems. Before I go any further the numbers below are from years ago, I didn't flow the stock numbers they were taken from various sources such as the 928 Motorsport website and the 928 Forum magazine plus Internet resources. I assume they are basically correct although I thought they might have been a little high. My numbers were of generated on a flow bench of the place that I was using at the time but the port designs are mine not theirs and they had no interest in giving inflated numbers. In fact the port was checked on a bench that can pull a 60" depression and they were conservative. They were flowed on a 103 mm bore.

LIFT______STOCK______MODIFIED
0.050"_____42cfm______53cfm
0.100"_____105cfm_____103cfm
0.200"_____187cfm_____234cfm
0.300"_____248cfm_____291cfm
0.400"_____267cfm_____342cfm
0.500"_____297cfm_____370cfm
0.600"_____306cfm_____382cfm

The valves used in my test were not optimized as they were tulip design, (all I had) previously I have several different valve samples made, all with different valve face angles not seat angles. Also I believe the optimum valve sizing to be 43 to 43.5 mm on the intake and 35 to 35.5 mm on the exhaust. The valves are way too small on the 928.

A common test of valve sizing in performance engines is intake valve area to bore area. A standard 928 has with a 100 mm bore to valve area of 27.34%, to put that in perspective a Formula 1 engine will have a bore to valve area of just over 40%. Now if we were to put those 43.5 mm valves into the 100 mm bore we still only have 37.8% of bore area. So if you were to put those 43.5 mm valve into say a 108 mm bore you would get a reasonable ratio of 32.4% still miles off a top race engine but capable of delivering in excess of 400 cfm at peak cam lifts and this figure should be doable at 0.500".

So when you compare what many 928 performance engines use which is 39 mm you get a valve area of 3.70 sq" versus 43.5 mm with 4.60 sq" an increase of almost 25%. That area is actually far greater due to the valve's window area.

Then you need to lift the valve higher that what has been commonly associated with the 928. I think a figure of 13.5 mm is reasonable. Porsche does this with it's race engines but uses Del West Ti valves, given their redline, normally around 9,000 rpm that is understandable. They are getting like motor bike engines.

I don't know if this helps the original poster but others might find it inciteful.

BC

Thanks slate. For this post/thought I was thinking of the ford coyote engine and its current development. There is much info about it and its mods, and its a four valve head like ours. The amount of info around is much larger compared to the 4v heads like on ferarris and such. Technology is moving very fast. Sme of that info is available online and some not.

You are talking about very large valve sizes.

ptuomov

If one is interested in copying any engine's cylinder head for forced induction, then I'd say it's subaru EJ25 and it's derivatives. It's the same bore and stroke, 4-valve head, only slightly different valve angles, and over a decade of high-performance development effort.

For oiling and crankcase breathing, modular ford and in particular Coyote are good sources of ideas. It's a 90 degree V8 with similarly constrained hoodline.