Anyone ever done it? Are there gains to be had? I searched and hadn't heard of anyone doing it??

 

Do you have a 1000hp miata?

 

I thought about doing it, but I am not sure if it is worth any hp gains.

 

Well I've got a 1.6 built with titanium rods, pistons and sleeves coated with iridium blown by Garrett 5541R running meth, hoping for atleast 2000 whp.

 

From looking around at some drag race imports, I think a very high horsepower car with a turbo larger than for road race applications would benefit from a 3.5". I have noticed that road race cars typically have smaller exhausts than drag race cars. Smaller exhausts for road racing gives them a little umf on the lower end.

I am puting a 3" exhaust on my N/A car, which is common in 4 cyl N/A drag cars, but unheard of in 4 cyl road race cars. I think the big turbo BP powered car that goes in the low 9's does have a 3.5" exhaust. You can see it on Dragtimes.com.

 

not worth it

 

i was close to doing it. but 3.5" stock is a lil more exspensive and just not a common size that is put in stock at many places.

im sure the price of mild isnt to bad, but stainless jumped up a bit from 3 to 3.5.

 

Yea I'm just wondering at what point the exhaust diameter size stops affecting spool and hurts low end power. I know it varies from app to app but just curious to see if someone has done thins and what the differences were.

 

Isn't "there is no such thing as too big" still the prevailing wisdom when it comes to turbos?

 

I bet it would help if you did it around mid car.

 

It would make a positive difference, how big or noticable I dont know...but it would not hurt. Id be concerned with the fit however, not a ton of room under a Miata and the 3" is tight in some places.

 

3" is a very close fitment. And by that I mean probably the biggest you can fit with traditional routing.

3.5 and you'd have to do side exhaust or have it dump mid car or something like that.

and unless you have a stroked monster huffing through a gt40r equivelant or larger and flowing enough for 1000whp I think its stupid and any gains would be minimal.

 

Even on the larger turbos the gains are small. Here is the only comparison I found, and it's with a 35r
http://highboostforum.com/forum/show...-2007?p=157428