Since the thread about Superchargers has revived I'll put in my two cents...I warn you it'll feel like more!

Kits for 1.8 or 1.9L engines:
Some have recently talked about the Sebring Supercharger Kit, so I checked out their website. They say their kit includes:

Eaton 62 Cubic Inch Roots Type Supercharger Mounted directly onto cast aluminum intake manifold Supercharger brackets
use stock fuel injection system except for Sebring-designed "downstream"fuel press. regulator that is boost sensitive No chip, Eprom changes neccesarry they say Claiming at least 215hp pending final results Price: others have seen it for $2995

I also remember seeing a kit in European Car awhile so I looked it up again.Its made by Motorsport Design/ Bell Engineering Group (BEGI). Their kit consists of:

Whipple twinscrew supercharger ( lysholm type) Air to Air intercooler (they say it drop air temps to within 20% of ambient) Fuel Press. Regulator ( raises fuel press up to 8psi per pound of manifold pressure)
Claimed 192 hp , 208 w/exhaust
Price: $4995 but $3995 as intro offer

The reason I listed the Motorsport Design Kit was because, Hey! Its always nice to have options and its good for comparison purposes. Anyway, someone had asked about opinions on the Sebring Kit. Well, first of all, as some have stated before, running a Roots type blower without an intercooler is not the best option. Roots type blowers run hot ( i.e. excessive charge heating). Well the reason they didn't use an intercooler is because they bolted the supercharger directly onto their aluminum intake manifold so therefore its impossible to add one. ( Sorry Gary H., even if they make a kit for the E30 you won't be able to add that aftermarket intercooler from HKS or Greddy). The most interestinf part is how they explain why they really don't need one. Here's a direct quote:

"Because our supercharger is hung off the engine in a position that receives large amounts of air flow, our total system efficiency is very high. It is not a stretch to state that the Eaton supercharger in our application acts as a sort of intercooler itself. We did not need to add the expense or complication of a flow through intercooler and the loss of boost that comes with its use."

Realistically, how much could airflow past a supercharger housing drop the temp. Seriously, even they say the intake charge air is increased by 69 degress. I'd be concerned about thermal stress on the engine and the heated charge increasing possibility of detonation.

Comparison with the MD kit:
I thought it was interesting how the Sebring kit produces more power (they say they expect above the 215hp range vs 192hp for MD kit) considering the supercharger they use is less efficient (56% for Roots type vs 68-72% for whipple), and the Sebring Kit lacks an intercooler. MD actually did a pretty good job of intergrating the cooler, but maybe the intercooler reduces boost enough to account for power difference? I'd really like to see what the dyno says. An interesting thing about these installs is how they both get around needing a reprogrammed chip and bigger injectors, instead relying on the existing DME and knock sensors along with addition of a fuel pressure regulator to handle the increased charge. The MD system uses a variable rate of gain regulator which raises fuel pressure in relation to manifold pressure. I'm assuming the Sebring system must use something similiar.

Cost:
Now having just said all this, obviously the Sebring kit seems like a pretty good deal at $3000, considering the MD kit is $5000 ( it still might be $4000, don't know for sure). Considering what I've said above though I'd probably go with the MD kit if I could get it for $4000 At $5000, maybe, my wallet would say Sebring but my mind would probaly say MD (or Mosselman, that's turbocharging but it is $4000),. Since I've hit the pricing issue, I'll take a shot at the whole BMW vs ponycar supercharger kit debate. Now kits for 325/M3 are even more expensive being $7000 from Dinan and $6000 from ERT. But these kits have additional components compared to the 318 kits. ( both have larger injectors, reprogrammed chips, the ERT has a larger air mass sensor, while the Dinan kit uses Turbotronic-10 which recalibrates the stock air flow meter....No Intercooler though on either kit) Anyway these kits are still significantly more expensive than kits available for american vehicles which usually range from $2200 and up but usually cost no more than $4000. Obviously they all use similiar and sometimes the exact same superchagers since most kits use either Eaton, Powerdyne, Vortech, etc. So there is no increased cost there. All have to manufacture similiar components (brackets, etc) but some do put in more work using better materials (Dinan w/ there brackets and CNC machined pulleys for example) so maybe a little increased cost there. Also the BMW kits, specifically the ones for 325/M3 do use reprogrammed chips so you've got to account for time and energy for all that development. But still I don't think this is enough to account for as much as a 75% premium in some cases. So what's my theory... well I think part of it is the fact that on a number of kits sold basis, people manufacturing or selling BMW kits will just not sell as many kits as companies that sell pony car kits. Out of all the E36 owners out there, what is the % that will actually put a supercharger on their car. Its probably pretty small. Now out of all the pony car owners out there and I figure there's a whole lot more of them than us BMW owners (NJ alone has more mustangs and camaros than you could believe), how many would put on a kit? On a % basis its probably not that much more but because of the bigger base of potential customers it will probably be a heck of a lot more than kits for us. The companies that sell pony car kits have the advantage of leveraging kits across many platforms adding even more to the volume factor. So kits for BMW's cost more to make up for fact that they will only sell a limited # of kits. But the #1 reason, which everybody already knows and either likes or wants to believe, is that they figure a BMW owner can afford it. So even if my argument for volume of sales were true, we are all more likely to believe the latter anyway.

P.S. With all my concerns over thermal stress, etc for the roots type blower used in the Sebring kit, I was wondering how much the temps for the intake charge increase for the 325/M3 kits (ERT & Dinian) which use a centrifugal type supercharger but no Intercooler. Maybe Will Turner can help us out on this info?

Rukman
95 325i (Modified)