|10-30-2016, 09:59 PM||#1|
Join Date: Apr 2010
I've been down this road a few times before. I'm looking to build an exhaust for hopefully the last time on my S52 e30.
What is the ideal size for a stock motor with m50 manifold? I'll be upgrading to Schrick 256/264 cams and either Jenvey ITB's or an Eaton M90 in the next year.
Thinking to install raceland longtube headers (I know they are hard to fit, but I've seen the issues and know how to deal with it), dual 2.25" merged to a single 2.75" at the first muffler and carrying that size through to the back. Mufflers would be a 2.75" single vibrant/magnaflow and a 3" vibrant streetpower with dual 3.5" outlets at the very back. The car is going to be turned into a street legal trackday car so I'm aiming to maximize power throughout the range while keeping noise down below our 90dB limit.
Layout wise would look similar to this but with a second muffler in the stock e30 cat location to keep noise down.
I'm a fairly competent tig welder with stainless and have plans to buy mandrel bends to cut and make them fit as nice as possible.
1990 332i, 4 door
2007 Z4M Coupe
2008 KTM 990 Superduke
|01-20-2017, 08:44 AM||#2|
Join Date: Jan 2014
Location: Los Angeles
Well, ideal size for a stock motor and ideal size for cammed and supercharged motor are two very different things... You can find some calculators online that will give you exhaust diameter based on your power goals. My e36 328 used to be supercharged and I recall that I was targeting 350-400 hp which matched to a dual 2.25" system. For a stockish s52 2.5" is the right size. Another thing to consider is that for a NA motor, header design ie primary runner size/length/collector size/shape, secondary runner size/length/collector size/shape and x/y merge placement are the critical parameters. But for a supercharged motor, you just basically want headers that won't hinder flow.
Regarding the raceland headers, I had them on my e36 and after going through the installation etc. I won't buy or use them again. They are just so thin, brittle, really roughly finished. It was not satisfying installing them.
Coincidentally I am in a similar situation as you with an exhaust project. I am in the midst of transforming the car from a street car that does a little autox/track to a "racecar" that does a little street time. Currently I have obd2 headers, magnaflow center muffler and vibrant streetpower muffler at the back. This combo has been fantastic. Not too loud, no drone and sounds mean on throttle. For the new setup I looked around for a long time until I found a set of euro s50b32 headers. You can actually find them and buy them pretty easily on some of the european ebay pages but they tend to be a bit pricey. But then again supersprint headers are quite a bit more expensive and the euro headers are about as good as it gets. Likely I will pair the euro headers with a tuned y merge into 3" with a muffler in the center like before going out back and splitting to a UUC RSC36 exhaust I had on my e36.
Hope this helps
89 E30 325i OBD2 S52 BUILD THREAD