racingminds

Okay I thought fer a while and figured this would be the best folder to post this, since it's a question relating to circuit racing/timeattacks. The modifications folder would just move too fast before the thread gets lost among many other new topics.

Has anyone fabricated and tested a single non-muffler race system from header back? I need to know if it makes more power/torque from 5000rpm to 8500rpm...anywhere else in rev range is not of concern. Need to know details on piping diameter, piping thickness and where the exit was chosen to be located. I know the 70mm singles such as the J's Racing 70RR, Amuse R1000 etc are the systems that make the most power while having sufficient back pressure. But i'm wondering if a full race system header-back can possibly yield better numbers?? Focus is on circuit timeattack. This will be for an AP2 with J's Racing SPL headers, Jenvey ITBs, Hondata KPro and a fully standard F22C block. Car currently makes about 244whp on a dynapack3000. Camshafts n engine work will come further down the pipeline.

crash

no matter how you look at it you can always get more for less when you make your own.

I have a 3 inch v-band hanging off my toda header running straight back with no bends until after the rear diff.
I have 2 45 deg bends in the system and that is all....one is at the back of the diff to kick the muffler over and the other is for the tip of the muffler so I divert the noise from the sound booths at our tracks.

all in all I think I spend about 400 bucks or so in pipe and a borla muffler.
I dont have many pics but here is one from the back. The 2 bends you see are the only ones. I also have another V-band back there so I can remove and change the muffler if I want for sound.

modMonkey

I remember seeing the Blue Evasive car running one, maybe you can PM them.

robrob

This works pretty well and it's cheap. This is the stock exhaust cut off just before the pipe that sticks out to the side (donky dick) with a Moroso racing muffler welded on and a turn town bolted to the back end of the muffler. The muffler and turn down are 2 1/2 inches. Attach it to a test pipe and you can't get much better. You could also just use 2 1/2 inch pipe and no muffler for some serious noise. Either way you will need ear plugs when you drive hard.



Check the exhaust exit requirements with the organization you plan to run with. It varies from "behind the driver," to "behind the rear axle," to "out the back or side."

assalbert

omg, those welds look like stitches

racingminds

Thanx everyone for the replies and pics~~ Appreciate it loads~

crash: So u are running 3" headerback to a 3" inlet muffler and I guess with a 4" tailpipe? Does it give u good power/torque thru the mid-high rev range(vtec zone)?

modMonkey: Thanx~~I'll try talking to the Evasive guys.

robrob: Hmmm...do u have any dyno tests on that setup?

I currently run a J's Racing twin Ti, as it's street legal and approved for street use here. What we want is to make our own race exhaust that will be for circuit-use only. It must however make more power/torque from 5-8.5k rpms to be of any use. Looking to use stainless steel since titanium pipes cost a bomb and aren't easy to get hold of here.

Muffler or no muffler is not really a concern. Sound levels are not restricted for the circuit and the events that we take part in. I love it loud, BUT the one concern is that the loudness limits my ability to hear other audible inputs of concern while on the circuit.

We are running Hondata KPro, so definitely will tune with the circuit exhaust system to get the most out of it.

For those who have tried and tested on the dyno/circuit, which option has yielded the best results??

1) 2" straight pipe to the rear from header, no muffler.

2) 2.5" straight pipe to the rear from header, no muffler.

3) 3" straight pipe to the rear from header, with 3" inlet bullet N1 muffler, 4" tailpipe.

4) Other tested/proven setups

Side-exit looks to be impossible since by the time the piping routes below the chassis bars running down the sides of the undercarriage, it might scrape the ground as the car sits quite low. Direction and angle of bends is yet another area as well.

rjones

Please run a muffler! The other drivers will thank you. The 1-2hp you will get is not worth the hearing damage. Race tracks are under a lot of pressure because of noise every where. You are lucky if your tracks do not have a sound limit because a hard sound limit is a pain. If everone runs a muffler it may keep the track from imposing a sound limit.

alvanderp

I made power across the entire VTEC range on my 06 when I went to nothing but a 2.5" Pipe with a 45 deg turn down just past the axle off the OE Cat. This was with the OE header as well. YMMV due to your setup, but in my experience, backpressure is a myth, especially on a car that spends the majority of its time in the top half of the rev range.

aceking66

I am thinking about doing this to my TTC car too, Crash by any chance you have a sound clip of your car? i would really like to know how loud is it

robrob

I haven't dyno'd it but it does flow very well. The Moroso muffler is about 70% straight through with the outside 30% of exhaust flow going into a swirl outside the core to breakup the sound. I have run on track without ear plugs (jumped from student's car into mine for TT session) and it was loud but wasn't painful.

I did it myself and ran out of CO2. The weld does seal the pipe though. Thanks for the input, ahh, ass.