Project M3 Part 7
The E36 M3 engine is phenomenal, even by today's standards. And because it's so efficient, the bang for your horsepower buck diminishes when you try to tune it beyond a good intake system, software upgrade or forced induction. But that doesn't mean there aren't other upgrades worth testing before jumping into a turbo kit.
In et 11/08, we showed you how to install some of these upgrades we're testing here, including UUC Motorwerks' RSC36 exhaust system and underdrive pulleys, a Riot Racing big-bore throttle body and Bavarian Autosport high performance ignition coils. Together they retailed around $1750 and took 4-5 hours to install. So this month we'll reveal our dyno test results.
The shop that installed these parts, MKC Performance in Kansas, has a Dynojet 424x four-wheel dyno. As we'd never used this dyno before we had to establish a new baseline because each dyno can be different.
Our baseline test gave us 226hp at the wheels (whp), which was down from our previous 241whp run on Imagine Auto's Mustang MD500 dyno (et 12/07). We also recorded 215 lb-ft of torque.
UUC/Corsa RSC36 dropped 20-lb, gained a more aggressive exhaust note at full-throttle and 7.4hp at 5800rpm
Exhaust
First up was the $899 UUC Corsa RSC36 cat-back system. While it's not the cheapest out there, it features exceptional build quality and is one of the best I've heard on the E36. It offers the best of both worlds since it's surprisingly quiet and doesn't drone when cruising, but once you get on it, the engine note sounds incredible.
On the dyno, the straight-through design and reported 37% improvement in flow was good for 229whp, with a peak gain of 7.4hp at 5800rpm. Peak torque rose slightly to 217 lb-ft in the mid-range.
A power gain and a 20 lb weight reduction meant we were off to a good start...
We also tested UUC's water pump and power steering pulleys, which came with the correct belt. They gained a peak of 5.5hp at 6300rpm
Pulleys
The $199 UUC pulleys were next. By under-driving the water pump and power steering systems they liberate the lost horsepower used to drive them. And to date we've not noticed any negative affect on our coolant temps or steering feel.
On the dyno, the pulleys initially weren't showing any gains because of the increased ambient air temp that afternoon, which affected the intake air temp and ignition timing. So we returned to MKC Performance the next morning to dyno under the same conditions as the exhaust test, and achieved 231hp at 6500rpm, with a peak gain of 5.5hp at 6300rpm.
With an additional 4mm opening over stock, the Riot Racing big-bore throttle body was good for a peak gain of 5.4hp at 6900rpm.
Throttle Body
Next was the $200 big-bore throttle body from Riot Racing. With a 68mm port to perfectly match the inlet port of both the M50 and M52 intake manifolds, coupled with the thinner throttle plate, we were confident we'd see a gain.
On the dyno, the peak power went up to 236whp at 6700rpm. RR's claim of an 11% flow improvement was good for a fairly consistent 3-5hp gain from 4000rpm onwards, peaking at 5.4 at 6900rpm. We've had no adverse affects to throttle response or engine idle either.
Coils
Lastly, we then decided to check out Bavarian Autosport's $450 high performance ignition coils. If the combustion chambers required more spark, these were going to show it.
Bavarian Autosport ignition coils smoothed the curve, saving lost power from a weak spark. with a peak recovery of 3.5hp at 5900rpm
While peak power and torque didn't change, it appeared the coils had smoothed the graph significantly, recovering up to 3.5hp at 5900rpm.
Given the several months we've now had the coils on the car, we've witnessed the other benefit Bavarian Auto claimed - improved fuel economy, which went from 21mpg previously to 24mpg average (over 27mpg highway, fully loaded), according to our calculations at the pump.
Driving roughly 15,000 miles a year at $4 a gallon, we were looking at around $350 in fuel savings annually.
Summary
When all was done, our M3's peak power rose from 226 to 236. Collectively, the parts were good for over 12hp at 6400rpm, with 5-10 lb-ft torque gain from 4000rpm to redline, peaking 10.8 lb-ft at 5700rpm.
In terms of acceleration, the 55-95mph third-gear dyno sweeps improved by 0.12sec, even though the humidity was 22% worse on the final test day.
The RSC36 is straight-through design, with unique "Reflective Sound Cancellation" technology | | |