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8v flowbench hijinks

linuxman51

linuxman51

Railspeeder Enthusiast #1
300+ Club
Joined
Dec 25, 2002
Location
mont, AL
So mine reads low apparently, but this is awful.
Got a 91 530 casting, T cam'd head from the junkyard a couple weeks ago to play around with and see what I could learn. Maybe do some cheap light/moderately ported and balanced heads, nothing too fancy.

Last night I finally got around to base-lining the thing. Its awful, but the news isn't all that bad.

For the sake of comparison, a stock 16v flows out at between 190 and 200 on the intake side (I can't remember what it does on the exhaust side, 170 or so? it blows a little better than it sucks, generally)

with no cam, and me plunging the intake valve open ~an inch, maybe more, it maxed out at 135 cfm @ 28. eeek. Exhaust was about 105 @ 28 blowing out.
So, I tossed the T cam in, to see what things would look like. it was a pleasant surprise (I guess...), but don't read too much into this..

130 @ 28 at max lift on the intake side T cam
95 @ 28 at max lift on the exhaust side T cam

All numbers @ 28
Results so far:

Intake
lift Ported Stock %diff
.050 34 30 +13.3
.100 62 56 +10.7
.150 90 82 +9.7
.200 111 101 +9.9
.250 127 118 +7.6
.300 140 125 +12
.350 145 122 +18.8
.400 148 123 +20.3
.450 153 123 +24.4
.500 159 124 +28.2

Exhaust:
lift Ported Stock %diff
.050 28 22 +27%
.100 46 38 +21
.150 62 55 +12.7
.200 78 70 +11.4
.250 90 80 +12.5
.300 99 90 +10
.350 105 93 +12.9
.400 109 100 +9
.450 114 102 +11.7
.500 117 106 +10.3

Whenever I swap 16v heads, I'll try and make it a point to toss it on there with stock cams and the solid lifters to see what it'll do with the stock profiles and perhaps the hotrod cams that i've got as well. Couldn't really figure out the best place to put this, its not exactly performance (yet), and I didn't take any pictures, so it doesn't exactly go in showroom, so OT it is..
 
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So since I'm not too familiar with flow concepts let me take a swing at understanding. The 530 head (standard U.S spec N/A head) flows worse with the turbo cam in it? Huh. And really the only way to improve the flow is through porting and such, correct? What are the flow numbers of other comparable engines or even something like a civic? I'm curious to see how they stack up...
 
.t.i.m.m.y.240 said:
So since I'm not too familiar with flow concepts let me take a swing at understanding. The 530 head (standard U.S spec N/A head) flows worse with the turbo cam in it? Huh. And really the only way to improve the flow is through porting and such, correct? What are the flow numbers of other comparable engines or even something like a civic? I'm curious to see how they stack up...
Click to expand...

It flows worse because it doesn't open the valves as far as he was manually pushing them open.
 
.t.i.m.m.y.240 said:
So since I'm not too familiar with flow concepts let me take a swing at understanding. The 530 head (standard U.S spec N/A head) flows worse with the turbo cam in it? Huh. And really the only way to improve the flow is through porting and such, correct? What are the flow numbers of other comparable engines or even something like a civic? I'm curious to see how they stack up...
Click to expand...

You will typically find that most heads flow less when measuring with a cam, simply because most cams don't 'max out' valve lift. It was surprising that it was that close to the max measured flow with the cam installed. the 530 casting is the same between the turbo and NA models, the only differences are slight variances in the cams, and sodium filled exhaust valves (vs stainless in the NA cars)

As to how they stack up, they're not even in the same league as your average honda head (which isn't really a fair comparison, a multi-valve head to a single valve head). This is why (well, one reason) hondas make so much power with relatively little boost, their heads flow that much better. Same for the 16v. It flows more.

I would further a guess that the ford 2.3 8v head flows about the same, but I don't have one to test (nor do I care to)... the numbers others have posted seem to match up with the numbers others have posted regarding the volvo head.



kyle242gt said:
Can't really overcome plane geometry can ya?
Click to expand...

I don't get it, must be too early, or not enough coffee, or something, but I missed this one.
 
kyle242gt said:
just guessing that the surface area is greater with two valves than one.
because you made a redblock run in the 10's, even if it was blue and used N2O. :nod:
Click to expand...

ah ok, I thought there was a joke stashed in there somewhere, and I was trying to work the angles.

FWIW, there's ~ 40% flow difference on my bench between a stock 16v and a stock 8v (on the intake side). So yeah, it is a bit difficult to overcome that out of the box. but it is possible, just takes a loooooooooooot of work.
 
ah ok. talking with sam about this, might put this to the test with a stock manifold on an NA car (at least initially). might be time to order a couple more elrings.
 
According to Heywood, there is a critical lift at which increasing the valve lift has no effect on the valve open area and thus the flow is not affected (at a certain pressure difference across the valve I'm assuming). The valve open area at this point is the area of the valve head minus the area of the stem. A quick test we did in the lab at 10" H20 (very small pressure difference) agreed very well with the equation he came up with, however, the units in his equation don't quite work out. I'll look for it tonight and post back if you're interested.

Seems like you would be past the critical lift at 1".
 
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linuxman51 said:
You will typically find that most heads flow less when measuring with a cam, simply because most cams don't 'max out' valve lift. It was surprising that it was that close to the max measured flow with the cam installed. the 530 casting is the same between the turbo and NA models, the only differences are slight variances in the cams, and sodium filled exhaust valves (vs stainless in the NA cars)

As to how they stack up, they're not even in the same league as your average honda head (which isn't really a fair comparison, a multi-valve head to a single valve head). This is why (well, one reason) hondas make so much power with relatively little boost, their heads flow that much better. Same for the 16v. It flows more.

I would further a guess that the ford 2.3 8v head flows about the same, but I don't have one to test (nor do I care to)... the numbers others have posted seem to match up with the numbers others have posted regarding the volvo head.
Click to expand...

Got it, that makes sense and i see the angle of 'max lift' vs. the actual lift with cams in place so yes, that number is actually quite good with the turbo cam installed.
 
someone asked about honda heads, this is an old crx 1.6L 16v head (numbers found on savarturbo, looking around at other things)

IN
1mm 42
2mm 74
3mm 105
4mm 134
5mm 160
6mm 181
7mm 199
8mm 218
9mm 230
10mm 242
11mm 251
12mm 260
13mm 266
exhaust

1mm 31
2mm 60
3mm 86
4mm 111
5mm 133
6mm 149
7mm 161
8mm 169
9mm 172
10mm 174
11mm 175
12mm 176
 
like I said, not looking to do anything exotic, there's enough other people with better tools, more time, and more experience for that. I'll have to play with the one i've got and figure out what kind of time investment its going to take and work out a reasonable price from there. This exercise is (hopefully) geared more for what can be done with stock head components and the ilk, to keep costs down for all involved parties. I'll check the oem flow balance after work, and depending on how the car club goes this evening, start working up an intake port as well as a fixture to get exact lift numbers rather than "I jammed my thumb down on the bucket and got about an inch of lift" (smaller springs for measuring, no I don't have the raw thumb strength to fully compress a stock valve spring :lol: )
 
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