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Date: Sat, 05 Dec 1998 01:28:02 -0600
From: "J. Leung" <>
Subject: Re: [E36M3] turbos and superchargers

Personally, I think if you're gonna do forced induction, you should do a setup that uses as clean as a fueling system as possible. After all, 90% of the work in these systems is figuring out proper part-throttle fueling. How ya gonna get enough fuel at part throttle without having the Motronic adapt and actually _lean_out_ full throttle blasts?

Getting enough fuel at full throttle is easy. Getting the right amount of fuel at part throttle - that's the hard part.

So who does this leave us with? Jim Conforti. Retain the factory Motronic and use larger injectors a la Jim. So who does this leave us with?

ERT superchargers and Active Autowerke turbochargers. If ya want something blessed by Jim, ya go ERT or ya go AA. (I think Jim _may_ be working with RMS of Vortech supercharger fame too)

So now, do ya pick a Powerdyne centrifugal supercharger from ERT, a Vortech centrifugal supercharger from ERT or RMS, or a Mitsubishi turbocharger from Active?

All these stage 1 kits retail for 6 - 7 what's the difference?

Well, the supercharged kits from RMS and ERT do not come with an intercooler. T he turbocharged from AA kits do.

That said, let us note that intercooling is, of course, a very important part of the equation, as it 1) creates more power by decreasing intake charge temps and 2) increases reliability by decreasing the probability of engine knock by decreasing intake charge temps.

What other factors to consider?

Well, I *had* an ERT/Powerdyne kit on my car. It provided a nice boost in power over 4000 rpm. Why only above 4000 rpm? Because its a centrifugal supercharger, not a roots supercharger like Eaton builds. Let it be known that the Vortech units are also centrifugal units. You cannot get around the fact that centrifugal units simply don't make much boost until you get the revs up. Mash the gas at 3000rpm and you might get 1 pound or 2 of boost....barely anything.

A centrifugal supercharger is really just the compressor section of a turbocharger driven by a belt connected to the crankshaft. If you're at 3000rpm, you're gonna get a pound of boost. If you're at 5000 rpm, you're gonna get four pounds of boost. If you're at 7000rpm, you're gonna get 6 pounds of boost.

Let it also be known that Powerdynes are quite susceptible to bearing failure. They bust all the time. Even after Powerdyne re-engineered the blowers in late 96, they STILL melt their bearings.

Granted, the Vortechs don't bust, but they're noisy, and they're STILL centrifugal designs.

Okay, so what about Active Autowerke turbos.

First, the drawback -> it shares engine oil as a lubricant. Its gonna put some more heat in your engine oil. But let the car idle down for a minute or 2 before you shut it off, and you're fine. Gonna run at Wide open throttle all day long? Install a Euro oil cooler. Then you're fine. But for street driving, you don't need one. you're fine.

So what else?

First, *forget* turbo lag. That damn turbo they have in stage one spools instantly at like 1700 rpm, and you get full boost at around 2600rpm. And that's 7 pounds of boost not 6. That's full boost at 2600 rpm not 6000 rpm !!!!

Second, the intercooler is included.

Third, AA uses Mitsubishi turbos. Mitsubishi is a major automobile manufacturer...their turbos are bulletproof enough to be used on _production_ cars AND trucks all day long. I don't see any Powerdynes or Vortechs being installed on production vehicles. If the turbo is good enough to be mounted on a Mitsubishi turbo diesel truck that see torture every day, ite good enough for my car.

Anyways, the bottom line is, I got rid of my ERT system to get an Active Autowerke system, and I even flew down to Flordia to research AA's shop and drive their cars. I stayed with AA for 2 days, drove all their cars, picked and poked all over their shop, and decided I wanted their stuff. End of story.

I made a little web site about my experience at:

When my car was ERT supercharged (a 2.5L) it made 300hp _at_ 6300 rpm and 254 lb-ft torque at 5700rpm. Real screamer up top, gutless down low. I got creamed by 93 325i's down low all the time. (I had a 92 325i..non VANOS)...when I had my supercharger!

An AA 325i turbo stage 1 makes 300 hp _at_ 5900 rpm or so, and, get this 295 lb-ft torque at around 4200 rpm.

That's a shitload more torque at a much lower rpm, and that means a shitload more real world flexibility and driveability. In fact, this is indicative of almost all properly sized turbo applications... turbos make shitloads of torque, more so thhan anything else, and remember that F=MA, so torque is directly proportional to acceleration, NOT horsepower

That my dollar's worth of input, it took me 2 years to figure all this stuff out. Take it or leave it, but I know what I would do.

Jason Leung
92 332i turbo wrote:
> i'm interesting 'bout supercharging or turbocharging the M3s too!! even tho,
> i'm just a E30 M3 owner <hope u guys don't mind?!>, but i'm currently selling
> my E30 in order to get a E36 M3!! and i'm quite sure that i'll be either
> super/turbo charged the car someday. so, i also wanna know any pro/con 'bout
> both charger as well as the brand, like MechTech, ERT <my choice>, Turner,
> RMS, and Dinan.
> tks in advance and hopefully i'll be not long "duck & run" around this digest
> soon!! =P
> Gary =)

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