Let's see how much m20 heads suck.

[digger]

This is common procedure for flowing bare heads. When doing port research, the manifold will be attached as well as a throttle body minus the plate. The clay may vary 1cfm or so pending the shape, but when you lightly peel it off, it stays near it's original form.

yeah i know it is but i I have never liked the fact that the opening to the head is not perpendicular to the centreline when flowing but it is when it is operating.

[ForcedFirebird]

you can work out the hp potential from the CFM, the stock head at 170cfm is about 260 bhp.

Any increase from this adds to this proportionally to the potential. The key word is potential, the real hp will depend on:
- how well the system as an overall system flows
- what rpm the exhaust is tuned for (primary and secondary length and diameter)
- camshaft events and profile
- what rpm the intake is tuned for (intake runner length and diameter, plenum size)

This is why the best heads are flowed as a unit with the intended manifolds on it.

Potential is linear, the actual head flow is not.

We can get in to exhaust, but would like to keep this thread about flow.

http://www.e30tech.com/forum/showthread.php?t=106851

yeah i know it is but i I have never liked the fact that the opening to the head is not perpendicular to the centreline when flowing but it is when it is operating.

We have flowed them in various configurations, can even flow with the actual exhaust on it, the bench was designed around this kind of testing. Sure, it's easy to say "this head flows xxxCFM: and when the intended manifold is bolted on, it drops, might even bring it back down to stock bare heads.

In the past I have gotten a unit (heads/manis(s)) to flow more than a bare head.

[ForcedFirebird]

yeah i know it is but i I have never liked the fact that the opening to the head is not perpendicular to the centreline when flowing but it is when it is operating.

We started messing with clay, adding material in places, changing the shape etc. The clay can be shaped in a way to gain ~6CFM.

We are baking the carbon and blasting a manifold now to put on the head to keep the results stable. Hopefully we will have some results today.

[ForcedFirebird]

Well. The eta, seta and 885 manifolds have been flow tested. The results are very surprising.

[future rs]

Well. The eta, seta and 885 manifolds have been flow tested. The results are very surprising.

And....?

[Balleristic31]

Post results? :p

[ForcedFirebird]

eta manifold is better than you think. Let's start there.

[ForcedFirebird]

[ForcedFirebird]

This is with the manifold attached, injectors installed, all vacuum lines blocked and throttle locked open. The non-test ports were also taped shut to prevent cross flow.

http://wot-tech.com/pdf/BMW%20M20%20Comparisons.pdf

[camip]

From that chart the eta doeant look to good.

[TobyB]

Really doesn't make you want to put a high- lift cam in there, tho, does it???

This is fun- thanks, John!

Ever since reading the Vizard (?) book where chapter 3 is all
about buying 3 shop- vacs and making your own flow bench, I've wanted to do it too...

t

[digger]

very much an anticlimax

i think it is worse that i thought it would be

you go from being able to make 260bhp to 190bhp;) by fitting the ETA fanimold

now it is time to tell us some runner lengths and the diameter at various cross sections for the full picture


with the 885 and b25 manifold it would be nice to flow each runner to see any distribution differences

[ForcedFirebird]

very much an anticlimax

i think it is worse that i thought it would be

you go from being able to make 260bhp to 190bhp;) by fitting the ETA fanimold

now it is time to tell us some runner lengths and the diameter at various cross sections for the full picture


with the 885 and b25 manifold it would be nice to flow each runner to see any distribution differences

We are several tests in ;)

The variance between ports are negligible, extremely close to equal between castings and individual ports

[ForcedFirebird]

Also, Digger, those numbers are full "I", full sETA and full ETA. Didn't post our findings on mismatched parts.

[u3b3rg33k]

very much an anticlimax

i think it is worse that i thought it would be

you go from being able to make 260bhp to 190bhp;) by fitting the ETA fanimold

Mismatching notwithstanding, the comparison is moot. Why on earth would you do that to an engine that strives to be a turbo-free diesel?