Lizard928

Gretch,

How long have you had your car murf SCed for now?

And please do get the latest upgrades for the setup, they make a big difference.

awaino

How does the 928 Specialists supercharger rate compared to the others suggested?

AO

First of all... the 928 Specialists' kit is not available anymore. SO let's get that out of the way. Hans purchased all the fixtures and some other parts, but I think he has been swamped with stuff and has not quite pulled everything together yet to offer the kit again. I'll find out tomorrow.

I have two of the 928 Specialists kits and I have also installed 1 Murf kit myself and I have helped installed 2 other murf kits. So I know both of them, and am probably the best qualified person to answer your question.

They are night and day. The 928Specialists kit uses a twin-screw supercharger while Murf's uses a centrifugal. The power is more immediate with the TS but then holds at that level. Great for off the line. The centrifugal builds boost as you get higher in the RPMs... and feels like it's just getting faster and faster, because it is. TS is better suited for autos and the centrifugal is easier on manuals - but not exclusively. You'll need to run an upgraded clutch with either kit. The autos are fine as is with either.

The Murf kit is probably the easiest kit to install and service, but as with any kit, you'll only be served as well as the health of the underlying car you put it on. I personally prefer the looks of the twin-screw over Murf's, but that's just an aesthetics thing. Murf has done an amazing job to keep things clean and tidy on his kits. Murf has also spent tens of thousands of dollars perfecting the hardware to make it reliable, whereas my twin-screw setups have had more than their share of "issues" (They're fixed now, but it took some doing.)

Lizard brought up a good point about chips. Many people think the hardware is 90% of the kit, but that's a fallacy. I have spent countless hours on the dyno with Murphy and literally thousands of dollars to get the tunes just right. Luke Stubbs, is a dyno god! He can tell you exactly what's happening - but it still takes a lot to get it "just right". I tuned my GT there with the 928 Specialists kit (that i modified) and it puts 500 at the wheels ... okay 497... While, yes, we do follow the general rule of pulling 1 degree for each pound of boost - that's just a rough guideline for a starting place. Then the work begins, and we tune it for the engine, the kits, and the behavior of the car. I want to make sure people don't get the impression that you can just take the stock maps and pull 1 deg/psi. It's not that simple, but that would be better than running stock timing for sure.

The Murf Stage 3 puts 500-ish at the wheels (I've seen 490's and 500's) so my TS and the Murf kits are very evenly matched for power. The last time we dragged, I was able to get a very slight jump, but then he reeled me back in. In the end, it was the quickness of the shifting in the auto that Murf was driving vs. the manual in the GT that allowed him to edge me out. Good times, though!

Here's the biggest issue though... My intercooler sprung a leak 2 years ago and I had to pull the motor to get to it, and I still don't have it fixed and back together. If I had a Murf kit, I would have been back in business in a week. So yeah... Murf kit wins.

I have no experience with other kits. Although I did get a ride in the 1,000 HP twin-turbo that Todd T built.... HOLY CRAP!, but that's not a kit. It's a work of art.

Carl Fausett

Not for everybody, but our Stage III kit uses the very big and reliable ProCharger P-1SC or F-1A blower, and we offer it with and without new engine management and injector wiring harness.
The P-1SC uses helical cut gears for those who want it quiet, while the F-1A gears are straight cut for those who like the supercharger "whine". Your choice!

The kit produced 516 HP at the tire, 607 BHP at the motor on a 1991 GT.

More info here: http://www.928motorsports.com/parts/...harger_kit.php


A quote from our website and this Stage III kit: ... i mention this because I agree with AO's comments above. Our experience has shown no two engines/cars are the same and you cant just mail a chip and call it a "tune". Some dyno time is needed to bring it in the rest of the way, and confirm the tune for engine safety.

ptuomov

You should also consider turbos. A turbo kit is more expensive, but also has a higher power potential...

...and is (in my opinion) cooler than a supercharger! ;-)

Here's a turbo kit on a GT: https://www.flickr.com/photos/928tt/

You might also want to search Peter deJong's posts and perhaps contact him to ask about his experiences.

If you aren't going to open the engine to lower compression, then I'd still consider an '87 S4 as the basis for the boosted car.

hacker-pschorr

The only reason why the Murf928 kit maxes out at 500rwhp is that is where Tim wants it to be. His personal test car reached 560rwhp and was far from the end of the potential before he decided to scale it back. The next phase was a larger blower, but that project was shelved since Tim focused on the current products at hand.

Todd's supercharged car made 660rwhp and he will be the first to say there is a lot left on the table with that setup. That particular install is just as easy to install as a Murf928 kit, just never produced in a kit form (however it has been duplicated twice I believe).

The guys in Utah have made 600+rwhp with a supercharged S4 too.

If someone wanted to pay Tim Murphy to install a larger supercharger and tune it accordingly, I'm sure he would welcome the project. IIRC larger Vortech superchargers will fit in the bracket he makes,
There is also Todd's supercharger setup which I've talked to him about duplicating for one of my cars. It's just a matter of making another run of the custom pieces / pulleys.
The formula is already there.

AO

I believe Hans's kit will accomodate a 2.8l twinscrew which would put it at well over 600whp. Crazy power.

To my knowledge, no one currently offer a shippable turbo kit, but those cast part Tuomo posted recently sure look tasty...

blau928

A 2.2L autorotor twin screw is capable of 600+ RWHP in a 928 with proper intercoolers and tuning.

This has been done on a 32V mustang many years ago, and the 928 can surely do the same with the same compressor....

Just my $0.02

When I get done with my system, we should see another twin screw system for a 928. Granted it will be more customer bespoke than just a plain kit. However, a "kit" of parts is not impossible....

Another $0.02

ptuomov

I am guessing that John will want to install at least the first few XL kits himself. The plus sized system will be awesome, I've seen the models, prints, etc.

Gretch

looks like I finished installing my kit early in 2004. that is the date of the thread Hacker put up.

I don't know why, but a couple of the pictures I have of the process are dated 2001, that could be a camera error though.

So My Murph kit, which I believe was #3, has been on Gretch for a dozen years.Time flies.......... like my 89GT Supershark. She still pulls like a locomotive.......

Carl Fausett

... a nice thread. Civil, informative, and helpful. Congratulations to us! Good job everyone!

AO

I don't think so. Perhaps in 'theory' but in practical terms it just doesn't seem to wan to get there. Believe me, I've tried.

I know the Rustangs can do it... not sure why we can't. It may have to do with teh ratios between the drive pulley (crank) and the SCer pulley. The 928 stock crank pulley is fairly small in diameter compares to other cars. However, I was able to spin my original 1.7l to nearly 19k RPMs and got in the 470's. Now, I can spin the 2.1 at a much safer (and cooler) 15-16k rpms.

If you have some secret ideas, I'm all ears.

One of the keys might be compression ratio. The GT with it's higher CR is not ideal, so that might be it. Anyway... something to consider.

blau928

Hi Andrew,

The MX422 compressor is capable of 600 at the tires as you observed on the 'stangs.. The key is the system.......

Let me ask a couple questions:

1. Have you measured the intake restrictions on your system?
2. How big is the current intake and TB?
3. What is the current pulley ratio? (At 15-16k compressor speed, I guess 2.5 :1 with a 6 in lower (crank) pulley).
4. Have you noticed belt slip?
5. How many ribs does your sc drive belt have? (6,8,10)?
6. What fuel and injector map are you running?
7. What size fuel injectors are you running?
8. What size intercooler are you running?
9. What is the outlet charge temperature at 16k rpm compressor speed?
10.

You can also send me a PM if you wish to discuss more.

There aren't any secrets, but I have some ideas why it's currently not getting to 600...

Best Regards

Imo000

Blau, first finish your setup and see what it will do. There isn't much use to bench race or theorise what a certain setup might or might not do. There is enough of that on the Civic forum.

blau928

This is not about my system. It's about Andrew's question why his setup can't get to 600rwhp when the same compressor makes 600rwhp in a mustang....

If it were a civic it would make 1000000000hp