I was wondering after reading some books on exhaust systems for turbo cars. I was wondering if I have the right set up. I have a 3" down pipe to 3.5" cat back muffler. Should I to a 3.5" downpipe which I also have? I read that at 500hp the exhaust dia. should be around 2.5" Anyone have any experience with this dilema?

Thanks

Running a one off ss exhaust manifold (soon to write up a report on the forum) with a AF61
Front mount IC
E6K
4x850s
rx7.com pump

 

500 bhp on x4 850s? I doubt it will be safe....

ps,

I run a 3" de cat, HKS Hipower muffler, and 5" (2.5"x2) mid pipe for noise attenuation.


for 500-600rwhp I was always taught to stick to 3".

Cheers

George

 

3" all the way back, if you can, do 3.5".

 

When I said 4x 850, thats what I'm running at the moment. Soon to upgrade to 1600. Hey signofinfinity, how much did the split pipe quite down the exhaust?

 

I practically had the whole cat area replaced with a big round canister with two 2.5 ss pipes going through.the canister is about 2 to 2.5' long.

I'll try and find some pics of it before i got it installed. It run 1 into 2... then back 2 into 1.

sound is amazingly smooth and no apperent performance loss.

 

Thanks guys for the response. Anyone else??

 

You'll be fine with a 3" exhaust all the way back.

I doubt that pump will support your hp needs past 15 psi on the stock wiring. For many years the pump rx7.com sold was the supra tt pump, and after 15ish psi the efficiency of it nosedives. do a search for a thread i started entitled 'some fuel system ramblings' for more info.

 

Hey Goodfella, what do you mean by stock wiring? So what your saying is that if I increase the thickness to the wiring it would hold better? What if I used a boost-a -pump?

 

Howard coleman has good things to say about the b-a-p. Regarding the wiring, some people will run direct voltage from the battery to the pump, there are a few ways to do it. I went ahead and picked up a higher flowing pump than the supra tt one, an apexi bnr pump. again, go read that thread I mentioned earlier, it wil answer a lot of questions for you

 

heres rich's post he said to read for you lazy boys

https://www.rx7club.com/showthread.p...stem+ramblings

 

Back to exhaust set ups. Any other inputs????

 

Come on FD owners! Please help me with stituation! There has to be someone that can comment on this topic more in detail.

Thanks

 

On a turbo car the bigger the exhaust the more low end power you will have because the turbo will spool sooner. The greater the difference in pressure between the engine side of the turbo and the exhaust side the faster it will spool.

Top end power will be the same for 3" or more since 3" is "good for 500hp" as far as exhaust velocity goes (NA piston engine enginnering).

I had loud JIC Magic Spec 90 3.5" turbo back exhaust and full 17psi boost was 3,500rpm- went to quiet Racing Beat 3" exhaust and full 17psi boost at 4,000rpm and I lost LOTS of power in the 1,000 to 2,000rpm range where I used to cruise.

Now I run the Spec 90 3.5" front section and the RB 3" rear section and full boost is ~3,500rpm (haven't data logged it yet), it is reasonably quiet and just has less power in the 1,000-1,500rpm range than the full 3.5" exhaust.

 

Hey BLUE TII, are you running the dual tip RB cat back? Is it really quiet at idle? Thank for the feedback. I think I'm going to use the 3.5" downpipe. The only thing is that the catback is 4".

 

you want the front (Downpipe, midpipe, etc.) as big as possible. after that, the 3" is fine (e.g. 3" catback is no problem)

 

I am running the Racing Beat 3" turbo back exhaust system "Y" pipe and mufflers with a JIC Magic Spec 90 front pipe.

The complete RB system is VERY quiet when used all together.

My set-up isn't too loud with just the 2 RB rear mufflers, but it has a very booming bassy exhaust note that travels through walls and annoys neighbors/landlord late at night

My experiences correspond to what Manolis_D says.

 

Or you can do something a little different and have a ‘’exhaust cut out’’ from summit racing with a motorised valve that would allow you to go from a quiet exhaust to a very loud exhaust at a flick of a switch this is the root I have gone I haven’t tried it out yet as my car is in the garage having work carried out to it.

http://store.summitracing.com/partde...5&autoview=sku


http://store.summitracing.com/egnsea...+115&x=33&y=12

 

Thanks Guys for the response