I posted this in the welding and fab area too...I hope I can have both open to get some feedback.


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.

 

My last exhaust was 4' with a flex and turndown. No muffler. But that is going to change.

 

No muffler yikes, that must have been pretty loud/awesome lol.

I have some tracks in my area with db limitations so I need a muffler.

What are you planning on?

 

The loudest car at every event got kicked out of an autocross too. But the new set up will have a muffler. Still not 100% which one yet.

 

I was looking at burns ss mufflers but I spent about the same amount on everything I purchased as it was going to cost for their muffler.

 

get one, sounds beautiful. and if you want to down the noise, just put on a super trap as the exhaust tip.

 

already bought the stuff i listed

 

that's right, you did. never mind.

 

Race headers with cone collector 3" pipe and flexible dump down infront of the gas tank. Loud as heck . If you don't have ear Plugs chances are you will permanently damage your ears. We used a decibel meter at Bisimoto and the thing pegg at 125 and still had about 1500 rpm to go.
The beautiful thing is that almost everybody else here in SoCal Honda challenge makes the same ridiculous noise. You have to be there for a start when there is 15 cars from standing start. Makes the hairs in your neck stand up.

 

Oh, ear plugs are mandatory with my car both inside and outside (at the dyno).

 

lol yeah that wont work....

103db limit at Roebling which is 1 of 5 that are closest to me that I will be at.

92db at Sebring I believe.

I have been working on it today, I just said screw it whatever with the length. I have it terminating just in front of the fuel tank.

Maybe I will post a pic later....TIG welding is fun but Im not very good at it.

 

I do know that terminating it at the fuel tank makes it extremely loud inside the car but it will also make the car louder outside the car then continuing it out the back or out the side.

My car is turboed so its quieter to begin with but I had a magnaflow muffler with it ending right before the tank and it was freaking loud and couldn't hear anything else going on with the car, so it now goes all the way to stock exit for now

 

why not terminate it at the lca and angle it in?

Never got hit it by the noise police with that config.

 

What I do to get the best of both worlds for tracks that have noise limits and for those that don't:

I have 3" piping that leaves the header and ends just before the rear axle/control arm. It's mandrel bent at the turns and at the end of the piping it's flanged. For the tracks with no noise limits, I attached a flanged turn down. For tracks that have noise limits, it's flanged on the other end of the piping and leads to a 3" straight thru magna flow that exits the rear of the car. It takes less than 10 minutes to either install or remove the muffler and attachment.

Here are my dyno results:
In back to back testing:
For my H2 spec B16 w/SMSP header:
WITHOUT muffler and attachment= 7whp & 7lb/ft tq LOSS than WITH a muffler. It made more power WITH a muffler!! It's due to such big piping 3". Too big for a B16.

With a H1 spec K24 with Six Sigma race header, it nets +8whp GAIN WITHOUT muffler. Even using the 3" straight thru magnaflow, my K24 loss 8whp from using a muffler.

For your app. I'd consider doing the same with the flanged piping just before the rear control arm to extract every hp from that LS engine


And by the way, I used to terminate it in front of the gas tank with a turn down. I learned the hard way. Flames made its way into the cabin and caught my seat and me on fire. Might wanna think twice about that

 

Wow Sebring is 92dB? They must have gotten spoiled by those quiet tdi Audis.

As far as tuning, what I've always been taught is that, as long as the header design is properly optimized, you just want to keep it as warm as possible to keep velocity up and then keep it as free flowing as you can manage.

 

Vtecjj what type of muffler where you using? I dont see how a straight threw muffler could kill 8whp?

 

Very interesting thread anybody else like to share dyno results? I've got a Crx with b16 and It's time for an exhaust upgrade.

 

Thanks everyone, these are the exact things I was curious about.

I have already finished most of it... I could always add to it to terminate further around the bend maybe at least away from the fuel tank.

Those fire comments have me uneasy now lol

I had considered a vband setup for going with a no muffler setup but it seems most tracks in my area all have db limits. I could be wrong on Sebring but thought it was around that.

 

Ok so last year we had about 3 different exhaust on the car. As for sound it has always been loud..... We where never to loud to race. John made us a new exhaust that is one peice and has a turn down right in front of the gas tank. I am not sure if James has a pic of it but my one word of advice to you is use alot of saftey wire for that just in case situation. I got black flagged at Homestead because i didnt realize that the exhaust was dragging on the ground and falling apart. LOL so keep that in mind.

 

Here is my exhaust...ignore my goofy friends and the awful camera phone picture. Just a shortly exhaust that points down in the middle behind the driver. Its pretty loud i'm looking to replace it with something else so I can drive the car to the track instead of having to tow it.

 

Lou, I planned to run some safety wire through the ebrake holes. I will be adding a hanger in the rear as well for safety.

I went with a longer muffler and longer piping to quiet it down.


I will dyno at some point and see where it is overall, maybe I will setup a vband and make a no muffler add on down the road.

 

Anybody have problems with fuel expansion by terminating and turn downs at the gas tank.

 

Nope. Just don't aim it at the tank. The turn down will take care of that.

 

I will also be adding some heat shield stuff to the fuel tank.

Im coating it with some heat temp ceramic brush on stuff and then wrapping the whole thing with heat wrap.

 

Best post of the thread. I did the heat shield thing with my turn down and it helped a lot.

As for getting sound down, I get really low dB ratings (sub 92) with by only using this:



Linky:
http://www.supertrapp.com/product_se...emID=425-25190

I do not use the discs and I removed the little hooked tube and welded on my turn down. Makes great power and is nice an quiet. Best $349 I've spent on exhaust setup.