3S-GE : Cylinder - Cylinder ~ 'Flow variation'.... ?

[abently]

2nd Generation Head....

Was wondering if anybody had Flow bench data of a completely standard Head with the standard Manifold attached to get an idea of how lean you can safely Tune the Engine if your only taking AFRs from the Tail-pipe and not each individual Exhaust manifold runner....

All the info I've been able to get is that Cylinder 3 & 4 run leaner from Factory, but by how much is the difference between Cylinder 1 and 4.....?

Thanks in advance !!

[abently]

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[abently]

Bump for prime-time viewing........... someone out there must know......

[abently]

Well last bump ever.... maybe once more during the weekend just to be sure no one here knows.....

[Andrew162]

2nd Generation Head....

Was wondering if anybody had Flow bench data of a completely standard Head with the standard Manifold attached to get an idea of how lean you can safely Tune the Engine if your only taking AFRs from the Tail-pipe and not each individual Exhaust manifold runner....

All the info I've been able to get is that Cylinder 3 & 4 run leaner from Factory, but by how much is the difference between Cylinder 1 and 4.....?

Thanks in advance !!

well I was going to try answering this this morning with some basic remedial static timing advice (to maybe 13-14*), and use of PULP, but that's really stating the obvious. sadly I don't have any flowbench data or a link to any, but it might be worthwhile trying some of the forums these engines are used on to search for the elusive answer, like MR2OC or the GT4 sites.

sorry, best I can do for now.

[oldcorollas]

i'm not sure either and haven7t read it anywhere, but id you are concerned, stick some temp probes in the exhaust ports and use them as a guide when tuning.

if you have individual cylinder trim, and the right logging/phasing software, (and a fast enough responding O2 sensor) you might be able to phase the O2 readings per cylinder and go from there.. but it also depends on the exact flow of your injectors as that will affect it also.

unless you are tuning to the edge with timing, then 1 or 2 points of AFR will nto make so much difference under power (ie, 12.4 or 12.6AFR)

[abently]

From what I have found out, was that you need to watch Cylinder 3 & 4 EGT's.

[terryo]

I have data on G3 heads and G2 turbo heads, but are are different yours. The G2 turbo head, has a 4% flow drop in cyl#4 compared with others. We can usually fix some of this this with careful port work. I use 4 thermocouples attached to the exhaust pipes near the head to look for subtle variations. You tune minor variations with cylinder trim on Motec. cheaper computers just cant deal with this problem