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Thread: Dutch SR20VE dyno'ed - your opinions

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Posts: 11-20 of 81
2010-11-22 14:24:38
#11
It's not the heat of the gases, it's the volume that creates backpressure. So yeah, like Dre says, bigger exhaust, or at least upgrade to a bigger muffler.

About the cam switching; when you use a controller, you can tune the switching points for max power. The correct way to do that can be found somewhere on the forums.

I think it was both intake and exhaust too low first, then both high.

Then combine the readings to find the best switching points.

Here's a good thread on the other forum, with quite some info:

Cam Switch-over Points
2010-11-22 14:40:14
#12
Originally Posted by damasterpnut
I thought the gasses cool down along the way so 2.25 inch isnt that bad.
You are correct sir.

Originally Posted by M0J0
It's not the heat of the gases, it's the volume that creates backpressure.
True.

Originally Posted by M0J0
And the exhaust is WAY too short to cool down the gases so they lose volume.
Completely false.

With a stainless steel exhaust, the temps will stay higher than with a mild steel exhaust, but either way you have approx 800°F - 1,500°F gas leaving the exhaust ports of the head, and that cools to anywhere from 60°F - 200°F as it exits the tailpipe.

Tell me that's insignificant.

That is at the least a four fold reduction in temperature, and volume is linear with temperature/pressure so that's at least a four fold reduction in volume.

Originally Posted by damasterpnut
And would a grade 6 plug make more power or is that something for improving reliability?
I would use heat range 6 plugs for sure. 7s are too cold. You may gain a tiny bit of power. Mostly it's to avoid fouling of the plugs. If your plugs are already fouled, then you may gain a significant amount of power back.
2010-11-22 14:53:15
#13
I stand corrected. Don't know what I was thinking. And to think I studied Physics, once XD.
2010-11-22 14:56:45
#14
Thnx Ben, usefull info.
I will check the plugs and make a picture.
2010-11-22 14:57:29
#15
Originally Posted by damasterpnut
Thnx for the info Andreas
I thought the gasses cool down along the way so 2.25 inch isnt that bad.

And would a grade 6 plug make more power or is that something for improving reliability?


Go with the 5's if you are stock compression, cold dyno passes and hot dynompasses will be more consistent.
When I tested the f3's they did not respond to well too cam gear changes. Adding overlap just worsens the situation.
Play with the exhaust cam gear, the intake plus or minus just killed power.
2010-11-22 14:58:54
#16
Laurens, would you happen to have a graph of the run?
2010-11-22 15:02:37
#17
Also what is your timing on the topend of your rpm's,'I would lime to see the graph
2010-11-22 17:59:02
#18


Timing i dont know. Should check that another time while driving with consult hooked up.
2010-11-22 18:07:55
#19
I thought the ve ecu had 10degrees base..
2010-11-22 18:09:55
#20
Is it just me or should you be switching the cams around 6k rpm instead?
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