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Cam and I built one of these David Vizard budget flow benches

and of course the final results, before and after:

.050" 20.4 20.8
.100" 50.7 51.2
.150" 79.1 79.7
.200" 103.0 104.4
.250" 120.7 121.5
.300" 134.6 135.5
.350" 144.4 147.1 +1.9% (gainz not worth noting up to this point)
.400" 147.1 154.7 +5.2%
.450" 149.0 160.7 +7.8%
.500" 149.9 163.7 +9.2%
.550" 149.9 157.7 +5.2%
.600" 150.9 157.7 +4.5%

For clarification, these are the final results on the prepared head, not the stock one. They also include a couple of changes we made after we were able to flowbench the entire intake system, some of which were significant in their own right. It's Cam's thread so I'll let him tell you what we did.

What I got out of this is a couple of things:

First is that when Volvo made the...performance? variant B230FX, they knew the intake was doodoo for this purpose knew the cam would need to crutch the intake. Hence the infamous VX, with the V intake lobe and smaller X exhaust lobe. I asked my machinist (R&L Engines in Dover, NH) about the 75% exhaust to intake flow relationship (Google it if you're unaware). There's lots of internet conflict on this and while it makes sense to me, what do I know? Anyway, I asked if was a real thing and was assured that it absolutely is a real GUIDELINE, not necessarily a rule.

Second is that air is heavy and hates to turn corners, wherever they are. Wherever you can help it through port efficiency rather than port volume will help.

Finally, when you're REALLY TRYING HARD to improve performance, you really need to pull yourself back and see the package as a whole, from where air first enters your influence to when it returns to atmosphere. It's easy to look at it as a combination of individual pieces, but that might not get you the best result.

In short it took us probably 6 months to figure out that we could get about a 20% improvement in the intake system. Knowing what we know now, I took this opportunity to order a custom cam from Jones Cams in Denver for this engine. We'll let you know how that goes...next Summer.
 
I was impressed with the results of the turd polishing effort.

And you should be! I think you're developing a well balanced system.

In short it took us probably 6 months to figure out that we could get about a 20% improvement in the intake system. Knowing what we know now, I took this opportunity to order a custom cam from Jones Cams in Denver for this engine. We'll let you know how that goes...next Summer.

And a 20% increase is SOLID as a system. When I port a head and then someone says they're using the stock manifold I just ask "then why am I porting the head????"

That cam should be a very nice setup for you. I don't know how aggressive the ramps are, but I hope you're getting something that's less pointy than a VX :)
 
The 631 is a pretty neat design. The combustion chamber is located entirely in the piston and head gasket, and the intake port uses this much more modern high swirl heavily biased design:

XS6zp9El.jpg


Results were initially pretty promising:
631
0.05 20.4
0.1 51.2
0.15 79.7
0.2 110.9
0.25 139
0.3 155.7
0.35 165.8
0.4 175.5
0.45 177.8
0.5 180

But then something odd happened. Here it is versus a stock B230F port, both equipped with our test ported manifold:
631 listed first, then the 530.

0.05 17.5 20 +13.90%
0.1 42.9 51.7 +20.40%
0.15 72.1 82.7 +14.80%
0.2 97.5 108 +10.70%
0.25 117.6 123.1 +4.60%
0.3 131.3 133.8 +1.90%
0.35 139.9 140.8 +0.60%
0.4 146.2 143.4 -1.90%
0.45 150.9 146.2 -3.20%
0.5 154.7 147.1 -5.10%

Hmm?
 
Compare the angle of the throat of the port relative to the mating flange to that of the runners on the manifold. My guess is that there is s sharp turn that does not exist in the other combination.
 
Those 631s are odd ducks, I always wondered if they would be good platforms for modifications, I wonder how thick the runners are compared to normal 530 stuff.
 
Compare the angle of the throat of the port relative to the mating flange to that of the runners on the manifold. My guess is that there is s sharp turn that does not exist in the other combination.

This is the prevailing theory for sure. We tested the B21F manifold on both heads and the results were much better for the 631. I think it'd work best with a more upswept manifold like on an M50/M52. I have the numbers but I can't find them at the moment. Looked like a pretty even trade off between the ported 530 with B21F intake and stock 631 with the same.

I think there's a decent amount of potential in this thing but it's too rare and strange to really be worth messing with.
 
This is the prevailing theory for sure. We tested the B21F manifold on both heads and the results were much better for the 631. I think it'd work best with a more upswept manifold like on an M50/M52. I have the numbers but I can't find them at the moment. Looked like a pretty even trade off between the ported 530 with B21F intake and stock 631 with the same.

I think there's a decent amount of potential in this thing but it's too rare and strange to really be worth messing with.

The flow of a "heron" head is normally ok.... but it's usually a trade off for really heavy pistons and marginal high lift flow due to no diffuser angle in the valve job.

The intake port bias tho :omg:

http://www.italian.sakura.ne.jp/bad_toys/heronhead/image/2332890983_f99bb0e91a_b.jpg
 
I'd also like to say, for the record, that it took about 90 minutes to get the water back in at the appropriate level. For anybody wanting to recreate this I recommend using a MAP sensor and an arduino with an LED screen instead to avoid water evaporation.

Edit; referring to flow bench.
 
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