Normy

"I'm coming from a different perspective since I'm giving up my old sport tourer to buy the 928 and my old ride does the quarter in the low 10's and "

Care to elaborate?

N!

aggravation

Sorry, I should have realized leaving that hanging would raise eyebrows. I just didn't want to further sidetrack the thread with the inevitable comparisons that will arise...
So here it is, my old sport touring machine my trusty Kawasaki ZZR1200:



I'm told I'm getting too old to glide inches above the pavement and I can't take the kids for rides anymore because the thought of them going down with me scares the crap out of me.

drnick

i agree with michael, drive it and see what you think. fwiw i will be installing an old FAST system on to my 86, i got hold of the parts from abbey who was selling them on to upgrade to the turbo system although he never actualy had the supercharger installed. im taking my time to assemble the bits and pieces i need and customising the design slightly ie pulley and belt routing, but the bracket looks ok and others have confirmed the system to work well at low boost levels.

RyanPerrella

i dont see the point in getting a supercharged 928 and paying a premuim for it if you think that you want to change it and upgrade it. If your going to do all that just buy a different 928 without a supercharger what the hell do you need 2 SC kits for on one maching?

I would leave the one alone, and not go trying to play with it honestly. If you like the look of a different kit then buy that kit, but i think it would be foolish to try and pick and match parts from 2 diff kits, you will just drain your wallet and get no appreciable gains. I say just stick with the SC thats in the car now, what makes you think it needs to be improved?

I dont understand what your goal is really

RyanPerrella

the only think i would bother to upgrade if you still felt you had to upgrade would be adding an inline water to air intercooler and replacing those aluminum pipes with the intercooler. You said you wanted to know what you need to make it like the Murph kit, you would probably need the whole kit, they look similiar, and honestly ive never seen either one of thesse in person so i dont really know crap but i again say that why would you buy a 928 with a diff SC and pay a premuim for a SCed 928 only to want to cahnge it into a murph kit, if you want murph's kit just buy that.

All things being equal, they look awful similiar honestly, i dont know what changing components will net you powerwise. I am sure there is some tuning in there that could help with driveability but that stuff you could probably change without changing hardware and just tune the engine to maximum efficancy.

good luck though

aggravation

As to why I would think of upgrading the FAST kit.
As I understand it the kit in there will do 5psi and that is the limit so if it's possible to change out some parts to have more boost available it is something I'd consider since others have had much success with higher levels of boost.
If that "upgrade" would cost the same as buying the Murph kit outright then I probably wouldn't go that route.

The car I'm buying is supposedly in great condition (I haven't seen it in person I've only seen pictures, spoken with the owner and he sent me copies of the service and upgrades that have been done) If the car is as good as it seems it is then I'm not really paying a whole lot more for the SC based on recent sales of similar 928's.

If there is a market for a FAST kit I thought I could sell it on ebay and then invest the money it brings into either the Murph kit or the Turbo kit...

Obviously no decision will be made before I give the current configuration a chance. Who knows, maybe it's more than enough but I know how I am about my toys, I like to tweak them, it's not something you can put a dollar value on, it's a ride but it's also something I tinker with etc.
There is an entertainment value and for me it's a lot more rewarding than stuffing $20's in some dancers Gstring every other week end or buying the latest Big Bertha driver to try and get a few more yards...

hacker-pschorr

The differences are subtle but significant. The only items that I can think of shared between the two are the blower itself and maybe the blow off valve. He will be fine with this setup until he runs into a problem or wants to increase the boost. The issue of belt tension alone is worth the upgrade.

I do agree that unless this car is an excellent deal, he might be better off with a stock S4 - then adding one of Tim's kits.

MarkRobinson

Aggravation: the 5psi FAST kit was designed to run for a long time at a low boost level. It was purposefully designed so that the belt would just get enough wrap on the pulley so that it would slip above 5-6psi: we settled on this to keep people from accidentally over-boosting their engines (& possibly damaging them depending on tune) w/o obviously deviating from our instructions.

Tim was more interested in exploring the limits of the motor & redesigned things for higher boost: a dedicated tensioner that wouldn't slip, intercooling, & even discussions of cog-drive setups.

My opinion, sell it & go with a turbo system: sooo much more fun, I can't even begin to describe it: the rush of the boost coming on, passiveness of the system, normal driving, normal heat conditions, & the attention you get with people knowing you're turbocharged: priceless

aggravation

Mark, thanks for the reply. Is detonation still a risk with a turbo setup?

MarkRobinson

detonation is always something that requires preventative measures on NA motors. The Stage 2 kit is intercooled (very efficient) & the kits come with 2-ranges colder spark plugs for added security. The turbocharger's turbine was tested to be as back-pressure free to help eliminate the possiblity of detonation, & the entire exhaust comes with the kit, so there's no reason to spend another thousand on that: it's backpressure free & tuned for the turbo, & designed to keep the engine pulse-tuned.

Since the boost comes on fast on the turbo kits, staying under 6-7psi with stock chips is a good idea & use the SMT-6 with the MAP sensor & software with maps (that I'll provide) to pull timing above that.

For '85-86 cars you can connect the octane loop for another 3d retard: this is what I did on my 115mph pass on the quarter (after lifting to regain traction), about 8psi.

BrianG

How about using John's Shark Tuner and actually remapping the LH and EZK (for S4's), Mark??

MarkRobinson

SMT-6/Shark tuner can pretty much accomplish the same thing: reduced timing while on-boost. I could go either way for the S4's, but I like the idea of the MAP being used to sample boost to initiate timing retard: unsure if the Sharktuner can do that as I've not researched that yet.

Mark

Tim Murphy

Hi Aggravation.
The most direct way to answer your question is to say that both kits are completely different in just about every aspect so the list would get pretty lengthy. There might be 2 or 3 common components but that is about it. Regarding the reliability of the kit that is on the car in question is virtually impossible for me to say because I don't know what has been done. Reliability would play two roles in this situation; mechanical reliability of the sc system, and performance reliability in the systems integration to the engine and engine management.

From the picture it appears to be a 5 speed car. At a minimum there is $2k worth of supercharger stuff on the car that could be used towards one of my systems. If you are paying a premium for the car with respect to the supercharger system, I hope you find this helpful. One last thing is to make sure you get all the stock parts that came off the car.

Best of luck with your potential purchase!

aggravation

Tim, thanks for the info!
A $2000 deduction from the total cost of your kit would be a substantial savings. Enough that I'd definitely have to consider switching to the Murph version as a possible upgrade path...if an upgrade is in my future.

One question for you or any others reading this. The car has an air fuel mixture gauge in the cockpit to watch for too lean conditions, it was described as a bar graph kind of read out, was this something that came with the FAST kit and would that operate on the stock sensor or would that lead you to think that a new/improved sensor had been installed.

I'm trying to learn a lot in a very short period of time here so forgive the stupid questions I'm bound to ask a few more at least.
Thanks again to all for adding to my knowledge by chiming in here with your thoughts etc.

PS: The owner has saved all the original parts. From the take offs during the SC install down to the original wheels, exhaust etc. so it could probably be put back to stock pretty easily. It looks like I'll have a nice chance to pursue a number of paths... a turbo or a beefier SC, or leave it as is and just smile.

MarkRobinson

Basic air/fuel ratio gauges tell you if you're on the right path or not & whether or not your system is operating in closed-loop mode during normal driving, but best to purchase a wide-band O2 sensor (comes with the turbosport base kit)