sqml

any of you guys actually bought the Speedforce racing supercharger for the 968? im thinking about purchasing their kit. Any feedback will be greatly appreciated. Thanks

Eric_Oz_S2

You loose the air-conditioning with the SFR kit. The SFR kit is expensive compared to the other kits available, although it does include an intercooler.
Simplistically a summary of the kits is:

SFR ($6,200)
Intercooled
7 psi through Procharger SC
Uses fuel controller to set fuel (by intercepting the MAF signal - I could go on and on about this..PM me if you are interested)
No ignition timing adjustments (relies on knock sensor to retard ignition sufficiently) {Running stock timing even with 11:1 AFR on my supercharged S2 at this boost was bad - LOTS of knock and timing being pulled back by the DME}
No airconditioning
Larger injectors
Runs single sided belt
Highest boost and power of all the "stock" kits
315 rwhp

Design1Racing ($4000)
Non-intercooled
5 psi through Rotrex SC
Full re-map of ECU including fuel and ignition (arguably the most elegant solution of the 3 kits)
Keeps airconditioning
Stock injectors
Runs doubled sided belt to allow AC to remain (no slippage)
CARB certified
Orders for these are closing soon - they are made in batches, so not always available
Power unclear but somewhere around 250rwhp

928Motorsports ($4500 stage 1, $5400 Stage 2)
Non-intercooled
5 psi through Raptor SC
Uses rising rate fuel regulator to adjust fuel for boost
No ignition timing adjustments (relies on knock sensor to retard ignition sufficiently)
Option of Stage 1 or Stage 2 kit (stock or new injectors)
Uses single sided belt with back of belt to drive SC - some slippage reported, Carl is working on modifications to improve.
250 rwhp stage 285 rwhp stage 2)

Hope this helps.

MN

Eric:

It seems that you have looked closely at all three supercharger kits. From your short summary, the Design1Racing kit appears to be the most sorted one, although limited in the amount of power it makes.

Is there much difference between the actual different superchargers: Procharger, Rotrex, Raptor.

What are your recommendations/suggestions, if any.

MN

Damian in NJ

I've been told that designs s/c kit includes you signing a disclaimer that you won't talk about any problems about the kit on the internet . . . and their choice of s/c was originally the Raptor, but since 928 Engineering is the authorized US distributor for Raptor they had to make a second choice.

Eric_Oz_S2

Well, I think it depends. I wouldn't want to make that choice for you, and 2 of those kit vendors are sponsors of this site (D1R is the exception). Please be aware that the following is my opinion only and you should make your own determinations through discussions with the kit vendors. In particular, the D1R and 928M have put a lot of development into their kits and have great customer support.

If you want to keep AC, then the SFR kit is out. That should be your first decision.

The second decision is what you want to do with the car and how much power you want.

The other 2 (D1R and 928M stage 1) make similar power, and are of similar cost. The D1R has a Rotrex head unit that I prefer (it has a separate oil cooler) - but I'm also biased as thats the head unit I chose. The Rotrex units are extensively used in racing, haven't seen the Raptor used for racing and it appears to have some issues when driven to higher boost levels with overheating (although Raptor are upgrading their units, but not sure if this upgrade is part of the kit - and perhaps not an issue at lower boost). At modest boost as supplied in the kit (street driven), it doesn't make a difference.

The D1R kit is nice in that it is completely tuned (comes with a chip), while the 928M uses a RRFPR which I suppose is not quite as elegant. They are both good value for money.

If you want to use your car heavily for track days, in my opinion an intercooler is a must. The D1R kit or 928M kits don't have this as the vendors state it is not necessary for 5psi boost. This may be true depending on application, but I prefer the use of an intercooler as I live in a hot climate where sometimes the car gets tracked in 35C ambient temps. 5psi boost creates a temperature gain of 35 degrees C - you can't argue this it is simple physics. So 40C ambient becomes 75C intake. In comparison, adding an intercooler results an an intake temp of about 47C. I have verified the temperature increase (on the dyno and on the track) with an intercooler (80% efficiency rating) and it is <10 degrees at 7 psi max boost. Now increasing intake temps has 2 effects - a loss of density (this means that the 5 psi would be otherwise higher if it was intercooled) of 10%, and an increased tendency to knocking. However, intercooling can add drag to the system resulting in increased losses, and potentially making the intercooler dead weight. The key then is to use an intercooler with minimal losses - there is no point using one where the losses exceed the density increase.

I looked at the SFR kit long and hard for my S2, but the cost seemed a bit steep (especially once landed in Australia). To that end I decided to design my own installation. What I saved in cost though, I paid back through a lot of time invested on my own part. I was also a little unsure of the fuel controller solution. All up I spent more on my setup than the D1R kit or 928M kit costs.

So I suppose in summary, my personal preference is for a remap solution (that is what I did) and an intercooler for track use. If you are not going to track it heavily, the D1R kit would be my personal preference. But as I said you should make your own enquiries and determinations.

Hope this helps.

Eric_Oz_S2

It's funny you mention that, Raptor was my first choice (as it is Australian made), but they wouldn't supply their compressor maps which meant I couldn't confidently design a kit around it. Rotrex had better and local customer support.

SpeedBump

You are incorrect on at least part of that. The Rotrex was the first choice going back to 2006 before the project was stopped due to cost of CARB certification back then. Yes he did try to buy Raptor units later but as you said Carl is the distributor and that did not work out. I am actually happy that the kit went back to the Rotrex since it was my first choice although I am not thrilled that head unit gets modified to restrict it as part of the kit. That means if you want to make more power with the DR1 kit you will need to source your own head unit, this is not a restriction with the other kits. Although you might want to do some other engine work if you plan on really pushing the boost up and up just like you would if you wanted to turbo charge an NA 968.

sydneyman

while obvious since you said that SFR loses AC, i would just make a note saying that the 928M kit retains AC. Just for posterity.

As far as the Design1 kit, it seems to be a good kit but as you said, only available in limited quantities. I think his last batch is just about over so im not sure how available it will be/is.

Good luck on your decision! I was going down the supercharging route (and may still if my wife sees the light!) but im not sure if its in the financial cards. once i started thinking about finding an introductory 0% credit card, just for this purchase, i knew i should probably stop... haha.

MN

Eric:

Thank your for your prompt and detailed reply.

I should have said in my first e-mail that my car is a 944NA '86 with a 968 motor, it is street use only, and due to drivetrain considerations (still have my stock NA transmission) I should/must stick with a low boost setup. Since it is my daily driver and I am not good at nor keen tinkering, reliability is also a major consideration.

MN

tim944s

There is no disclaimer and there have been no problems. Just to clarify.

Dubai944

In that case I would stick with the stock NA motor. The idea that any power adder, particularly a supercharger kit on a 968, is going to be plug and play is likely to lead to dissapointment. A reasonable amount of tinkering can be expected and reliability is likely to be reduced.

I have the SFR kit on my S2 race car with 968 engine. The C2 procharger flows plenty of air and the self contanied oiling is a good feature. The head unit seems robust and has endured 2 years of very high temperature operation racing in Dubai at continual high rpm. The mount bracket is solid and the stock belt drive works ok for low boost. Would probably be fine on most street cars, but needs modifying for any high boost or racing application like mine due to belt slip issues. I now use a custom 8 rib, larger crank pulley setup for my application. The intercooler for the S2 setup is stock 951. The hard pipes and other bits and pieces fit ok. I never used the fuel controller as I have a standalone. The packaging was poor, everything just tossed in a box which broke during shipping and the follow up service from SFR was slow, but I got everything I paid for in the end. Expensive for what it contains really. Not a bad kit but there might be something more complete out there.

Having spent much time modifying and working with it I realise I would have been better starting with a bare head unit and making the rest myself, but at the time it suited me for a quick bolt on and I didn't know then what i know now!

odurandina

sorry if i'm curt (and i realize i wasn't asked)....

but, as a casual observer, and after having once been extremely excited about running a supercharger....

and after a long deliberation consulting with experts.... i've reached the following conclusions;


track ?

run anything you want since you've got infinite time and money (theoretical) to make repairs after each event...


street ?

1. a better exhaust (up to eliminating the cat altogether) on the current engine (and no chips).

2. a rebuild and intercooled turbo running mild boost — or....

3. a V8 chevy.

Damian in NJ

That's not what I've heard. Didn't warranty support issues cause the d1 and rsb breach?

MN

In addition, my car is not even a 968. Most likely I will need to replace the stock hood latch and the headlight linkage with hood pins and use a second headlight motor, in order to have the necessary space for the supercharger.

What I meant to say is that I do not want to have to do (substantial) R&D myself, and in particular don't want to fiddle with nagging and hard to resolve issues like belt slippage or fuel/timing issues.

MN

SpeedBump

Given your setup you should listen to whatever Eric and Dubai944 tell you since I believe they both are running 968 motors in 944 chassis, I have no idea how room for location of parts in the 968 kits come into play in that setup.