95 M3 project

[m3f_GG///M3]

I've owned a few m3's in the past everything from cam'd setups, sc setup, turbo built motor, and an s54 swapped as well.


In the past I never really did a full exhaust/cams, and did back to back dyno runs showing each stage of what the car made well until now.


This 1995 m3 I purchased over the winter came with fully stock exhaust, afe intake, and dinan tune.


I decided on getting something exhaust wise close to the euro m3. I picked up a set of euro ss rep headers from raceland , real euro ss race mid pipes, and euro evo e36 scorpion muffler to finish of the exhaust.


I also picked up 24lb injectors, and 540hfm(used not the best idea). Also RK tunes tuned at his shop .


Some pics .








Now the car was dyno'd with just the dinan tune, and intake. Car made 219whp/225wtq . Rpm signal was having some issues on the dyno during this whole process.


Once the exhaust was installed car picked up 10whp making it to 229whp/229wtq.


Then we added the 24lb injectors, 540maf(not working properly), and tune 245whp/241wtq.


Due to the rpm pick issue I'll post graphs based on MPH, and Rpms (about 1,000 Rpms or off).











Epic Motorsports sport cams will be installed hopefully soon. I'm not sure how much more it will make, but the car pulls pretty hard for what it is.


I'll try, and get some sound clips this weekend.

[m3f_Nate047]

Nice. In for results with cams. What fuel is the tuned for? How loud is this ****er with no cats?

[m3f_GG///M3]

93 octane . It is loud as ****.


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[m3f_M_Parallel]

Such an increase from just adding 24lbs injectors and 540hfm sensor?

It's not letting in more air because of that and even if you'd add 50lbs injectors, it's not going to inject more fuel, so that's pretty amazing.


Do 24lbs injectors make any difference with same fuel pressure/injection pulses? You'd thino it would mean equal fuel just being delivered through a larger opening.

[m3f_tsmith25]

Such an increase from just adding 24lbs injectors and 540hfm sensor?

It's not letting in more air because of that and even if you'd add 50lbs injectors, it's not going to inject more fuel, so that's pretty amazing.

The US s50 had 17lb injectors so with the free flowing exhaust, they were probably maxed out. Which would explain the seemingly large gain from the MAF and injectors.

Do 24lbs injectors make any difference with same fuel pressure/injection pulses? You'd thino it would mean equal fuel just being delivered through a larger opening.

Assuming everything else is constant, by increasing the cross sectional area that a fluid is flowing through, you will increase the mass flow rate.



There are three ways to increase the amount of fuel coming out of an injector; increase the pressure, increase the time that is is open, or increase the cross sectional area that the fuel is flowing through. Only pressure, and the cross sectional area will affect the flow rating, since that is an open flow number(not dependent on pulse width), how much it will flow if left completely open(24 lb/hr in this case). For fuel injectors, they probably have more holes rather than bigger holes, since the size and shape of each individual hole is important for fuel atomization.



If I had to guess, since the injectors seem to come in increments of about 3 lb/hr(17,21,24), that is probably how much a single hole flows. which would mean that the 24lb injectors have 8 individual holes, the 21lb have 7 and the 17lb have 6. those are just guesses though.

[Obioban]

Nice gains!


I love threads like this

[m3f_M_Parallel]

I thought they all had 4 holes. The pink's 21lbs? on my 328i do.


I have never taken out one of my 24lbs ones on my M3. With 5 bar pressure at them, this thing is very thirsty.


I always learned that same amount through a larger opening meant slowing down the flow, smaller opening, faster flow.

[m3f_tsmith25]

Like I said, the hole thing was just speculation on my part, I have not had an injector out yet to actually look at them.

I always learned that same amount through a larger opening meant slowing down the flow, smaller opening, faster flow.

sort of. for a pipe that is correct, with constant mass flow rate, a smaller diameter pipe will have a higher velocity than a larger pipe.



Those of you who are Mechanical Engineers please forgive me for not knowing the bernoulli equation off the top of my head... pulls out fluid dynamics book to clarify answer...



for a nozzle, which I am sure a hole has to be some factor(that I haven't looked up) smaller than the cross sectional area of the reservoir, or pipe leading up to it, to be considered a nozzle, velocity is proportional to the pressure drop from inside to outside. Inside is high pressure and low velocity, then outside is high velocity low pressure.



So for the fuel injectors, the exit velocity will be constant since our fuel pressure is maintained relatively constant. Which means that as the nozzles get bigger, the mass flow rate of the fuel will increase, while the velocity of the fuel leaving the injector stays the same.

[m3f_GG///M3]

Nice gains!



I love threads like this

Thanks. I will most likely be going with resonators as its just a bit too loud for me. Hopefully that will quiet it down a bit. Then it will be time for cams in the coming weeks.

[m3f_GG///M3]

YouTube (Short URL)













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[m3f_betrezra]

really like the decel tones..... burble pop!