I wasnt sure if this was better here or all motor...maybe both.

I have gathered some parts to do a simple race exhaust on my civic with a 1.8 non vtec, 150-190 whp.

4 feet of 2.5 inch ss

flexpipe 2.5 inch

4 inch round 22 inch length magnaflow ss muffler

no cat

turn down at the end

This is a simple process but my question is more for optimal power in theory. I can dump the exhaust anywhere after the driver seat so it doesnt have to be 4 feet, that is just what I purchased.

I know some of you guys have done this and I also know that tuning on a dyno is the best way to figure this out for sure but I wanted to get as close as I could for length etc.


Thoughts? Recommendations?

Thanks

I forgot to mention I have the tri y header at 2.5 inch at the collector as well.

 

i would dump it at the rear of the bumper. gasses can still get in your car regardless of speed if its dumped anywhere ahead of the bumper or not out a side.

 

If you really want to learn the fundamentals of exhaust design I would recommend you purchase a basic fluid mechanics textbook. You can usually find older edition textbooks for a few dollars. This will arm you with a basic understanding of fluid flow and help you make educated decisions. If you want to take it a step further there are some more advanced books out there on exhaust design, but be warned if you don't have any kind of engineering background it may be a lot to grasp.

 

Thanks, not an engineer but most of it makes sense to me.

I figured someone must have made a race exhaust like Im talking about? Im not looking for some crazy engineered piece, just maybe like a 3 foot section with a muffler over a 4 foot etc that someone had experience with.

 

theres not much to theory to an exhaust (unless you are referring to ways to sustain power meanwhile not hurting power) after the last collector of the header. The goal of a "cat back" is to revert exhaust gases away from the car, as well as sound.

exhaust manifold design, yes.....there is a whole bunch of theory and engineering involved.

 

I got some good feedback in the road race forum. dynos between muffler and no muffler etc.

thanks