How much backpressure is too much, and/or how much is acceptable. Assuming that it is measured in PSI.

I've tapped out a O2 bung plug, and will be attaching a short piece of copper tubing and at the end of that a pressure (i.e. Fuel) gauge. This is just to find out what the back pressure would be/is. It's somewhat of a moot point since I'll be installing some "custom" cutouts, but I'd still like to know. Plus that way whenever we want to test somebody elses I'll know. That's another reason that I went with the O2 plug, it can be removed and replaced with a new one and also can be used on others cars

Thanks in advance.
Troy

 

ah huh!
Yet another "black art" type question
Does anybody know or can anybody post flow ratings of different exhausts/cat-backs???

Maybe that will give me somewhat of a starting point.

 

I thought I saw that kind of info in a post a while back, did you try doing a search?

 

What would be even better would be to do some dyno runs while progressively reducing backpressure and then measuring the resultant gains. A "nice character-builder for the student" as one of my college professors used to say...

 

The next time I do a little dyno tuning I plan/hope to test (or at least do some runs) the difference with the cutouts open, partially open, and closed. This could be interesting seeing the differences, if any, in HP and TQ. Just for sh*ts and grins. I'll probably post some of the info, but it may be a little while, I want to make sure everything (i.e. A/F, timing, and PE vs RPM) is pretty close instead of wasting a lot of dyno time getting it. Not to mention we still have to "build in" the cutouts. I'm planning on doing a little "custom" work with some 3" tube with 3-bolt flanges from Dr Gas (they should be here Friday) . I'm either going to place them into the race pipes or at the bends in the Y-pipe for a "straight out" exit. What do you think... cool, or not?

 

im not too sure you could accurately tell the diff since there is not gonna ge a huge change either way unless your talking about starting out with alot of back pressure. and since theres not gonna be huge differences they could be disuuised by the margin of error that happens when you dyno also from my understanding the ls1 has to learn mods so if you just change the back pressure w\o giving it time to adjust in the pcm your not really seeing the longterm effect. but hell go ahead n do it if you gan get that type of dyno time and post it up id still be very ntrested in the results