S50 Exhaust Flow size

[Mulletproofed]

Hello All,

I just bought an 87 E30 with a 1995 S50 swap with chip etc. The motor swap was done very nicely, runs smooth etc. I just feel like power is being restricted. I do not have any e36 m3 friends to compare the motor.

Suspected HP Thief is my exhaust??

The Car has duel 1.75" pipes run into an e30 aftermarket stromung muffler.
(*1.75" dual pipe are almost equal in area to one 2.25 single pipe)

According to an exhaust site mentioned below, dual 1.75" pipes are capable of around 217hp. My car being chipped etc, i could see that as a limitation. I also feel that is does not rev through the RPM very fast.

YOUR THOUGHTS? Is my exhaust flow restricting my hp?

I used this website as reference

http://www.exhaustvideos.com/faq/how-to-calculate-muffler-size-pipe-diameter/

[justin_l_]

I doubt you would notice any difference changing the exhaust. It's probably not revving super fast because it has a normal flywheel, but it's drivable unlike a super light flywheel.

[matthugie]

Worth noting is that the S50 came with 17# injectors, same as the M50. I was down on power and found swapping the injectors out for some 24#'s and getting a new tune yielded huge gains.

[Mulletproofed]

That is good to Note Matt! I will look into injectors. As far a new tune? It currently has a Jim Comforti chip(at least the paperwork says), does that mean they re-program the chip on a dyno or some other software?

[justin_l_]

Worth noting is that the S50 came with 17# injectors, same as the M50. I was down on power and found swapping the injectors out for some 24#'s and getting a new tune yielded huge gains.

You have dyno numbers to prove it or just butt dyno?

A Jim comforti chip is an off the shelf tune that is better than stock but not as good as a custom tune on a dyno. A chip is essentially a tune that was done on a dyno with a car, then they back some stuff off to make it safe for all cars to use and mass produce it.

[e30rapidic]

24# injectors without a cam is overkill. Throw some 21's in there and you'll be fine.

[ForcedFirebird]

24# injectors without a cam is overkill. Throw some 21's in there and you'll be fine.

The m50/s50 injectors are good for well over 200whp. I have tuned an e36 race car making 223 with a stock 413 red label and 17lb injectors with plenty of room for more.

Cammed s52 with all the bolt ons made 240's with the pink injectors, plenty of room on 24lb injectors too. Probably would have been fine with 17's. Just get your car tuned properly for whatever you have. Parts matching will make/break you.

[Mulletproofed]

Thanks guys. I will look into getting a tune. Does this mean the comforti chip will be reprogrammed and lost? Also, about the exhaust. It's whisper quiet with current e30 exhaust. I want to put a vibrant on. I don't know if they flow any better but I need a throaty sound now!



E30 rapidic. Mine is a vert as well. They are fun for the summer so far!

[matthugie]

You have dyno numbers to prove it or just butt dyno?

A Jim comforti chip is an off the shelf tune that is better than stock but not as good as a custom tune on a dyno. A chip is essentially a tune that was done on a dyno with a car, then they back some stuff off to make it safe for all cars to use and mass produce it.

The short answer your question is no, I haven't had it back on the dyno since the injectors and new tune (TRM). However, comparing straightaway speed and acceleration over sessions at VIR does indicate significant gains. The setup before was OBD-I S52, 3.5" intake and MAF, raceland headers, full exhaust with no cat, and a Dinan tune. Last fall it put 218 to the wheels on a DynoJet, and AFR's were good but getting lean towards the top of the rev range. An OBD-II e36 M3 with just an intake and cat-back put 223 to the wheels on the same day, so it was definitely down on power.