[k8R8k]

I can't find any information regarding recommended exhaust diameters for single turbo applications.

Has there been any testing on this for Single Turbo N54? Is a 3.5" exhaust beneficial on this platform?

I found this article:
http://www.superstreetonline.com/how...ust-test-tech/

Any information would be great, hopefully some of you high power ST guys/tuners can help.

Thanks

[The Leopard]

3" has roughly the same cross section as the stock exhaust. Most people go 3.5" or dual 2.5". 4" is ideal IMO, but requires a custom job and no cross brace.

Google Supra 4" exhaust Dino, and you'll see huge gains going to 4" from 3.5" when you're in the high HP range.

[Sered]

I'm going with a 4" single on my E90 with the VM kit. Not sure if you're referring to an E92, but there's no cross-brace for it to cross other than the pan in the middle (and a 4" single takes up less room overall than dual 2.5")

[The Leopard]

Originally Posted by Sered

I'm going with a 4" single on my E90 with the VM kit. Not sure if you're referring to an E92, but there's no cross-brace for it to cross other than the pan in the middle (and a 4" single takes up less room overall than dual 2.5")

Yes, I'm referring to the brace the E92 has. The 4" requires much more clearance than the 2.5" pipes as they are stacked horizontally, not vertically. I've done measurements on the car for the 4" system I building, but later abandoned.

Keep up posted on your exhaust progress!

[k8R8k]

Thanks for the input guys, mine is an E92 and I'm not prepared to lose the cross brace so maybe I'll go for the 3.5" with an external gate venting through its own pipe.

[Riceball777]

I thought there there were no benifits from a going with bigger than a true 3 inch straight through exhaust system unless your well over 700whp. That's the consensus in the lancer evolution forums at least.

[k8R8k]

Originally Posted by Riceball777

I thought there there were no benifits from a true 3 inch straight through exhaust system unless your well over 700whp. That's the consensus in the lancer evolution forums at least.

I don't have much knowledge regarding exhausts but the article in the first post made me question the standard 3" choice.

The article is based on a 2JZ making similar power to single turbo N54s and they're both 3.0L 6 cylinders. I'm not sure if it makes a difference but wouldn't it be a better comparison than the 2.0L 4 cylinder engine? I could be wrong...

[rac]

note that comparing x-sectional areas between dual mids and a single is not apples and apples. dual pipes of the same x-sectional area as an equivalent single have a higher pressure loss over the same distance. this is because there is more surface area / flow area with dual pipes. you dont need to match the area of 2x 2.5" pipes to get better flow out of 1x single pipe.

[Sered]

Originally Posted by Riceball777

I thought there there were no benifits from a true 3 inch straight through exhaust system unless your well over 700whp. That's the consensus in the lancer evolution forums at least.

That's most likely because the 4G63 head doesn't flow well and the major exhaust restriction is in the head itself. Not so on the 2JZ. It's been well known and documented for over 10 years that running just a 3" pipe is a huge power loss once you get into the 500whp+ area. I was always told if you're going over 600whp that you need to start looking into 4" exhausts, or at least the midpipe and catback portion. A true 4" ******** isn't necessary until later. Hell, there used to be (not sure if its still around) a 5" exhaust out there.

VM kit is a 3.5" ******** and I'll be attaching a 4" single all the way back.

[elijahcole92]

Originally Posted by The Leopard

3" has roughly the same cross section as the stock exhaust. Most people go 3.5" or dual 2.5". 4" is ideal IMO, but requires a custom job and no cross brace.

Google Supra 4" exhaust Dino, and you'll see huge gains going to 4" from 3.5" when you're in the high HP range.

Here's a comparison i did a few years back on my 97 Supra.

http://www.supraforums.com/forum/sho...4-quot-Exhaust!