Fishey

Even at 4000+ Rpm you get off the throttle and back on the throttle and the bov releases on a turbo it has to spool again. A Supercharger runs off the engine and so you still have all that boost instantly there is no respool. Thats why I would prefer the supercharger when it came to handling.

hacker-pschorr

I've seen Monster Garage to, seeing Jessie grab some pipe and weld up some very nice headers.
Lets come back to reality here. Lets take the "average" 944 or 928 owner that has very basic wrenching skills - this is where the market for a 944NA turbo/SC kit and 928 is directed.
For the average wrench, simply installing headers on a 928 is a major task - yes I've done a few - on a lift. Lying on your back with the car on jackstands would be a nightmare. I'm sure the 944 is much easier.

I have a friend that made a custom crankshaft out of solid billet for a VW flat 4 to be installed on a motorcycle frame he also made. To him it was a simple process - doesn't mean anyone can do it.

When a factory turbo 944 can be bought for $6k or under - the cost of any kit would far outweigh the benefits of selling a NA and buying a turbo - but you already knew that.

Geo

Yes, let's. Please. I never said anything about Monster Garage or anything like that. I'm talking average folks.

And there is the difference. The 944 folks are defeated in their own minds before they even get started. THAT is the difference.

hacker-pschorr

Sorry Geo - sombody with ZERO welding experience cannot go out, buy a welder and a bunch of pipe, and fab up a 928 header with any amount of qualty and also call it "easy".

John..

Whatever....as my Father used to say: "Always consider the source"

hacker-pschorr

Care to elaborate?

Danno

Anyone have a graph of the boost-curve of a centrifugal SC???

BC

GEO SAYSUh, actually, it does very much seem so:

and
and

Sounds pretty snappy to me. I thought we were being civil? (except for the fact that your communication is at least dimeaning, if not totally patronizing.


Just for effect, and some honest photos - then I gotta go:










I have more, but....

Tony

It was pointed to me in the 928 forum that some claim here that Superchargers dont make full boost until redline. Im my application this will shoot holes in that theory. In reality it is dependant on the TYPE of SC used.
I will have better proof once i get my LM-1 data logger installed..in the meantime i think the vidoe shows it well.





On the dyno chart above i was getting belt slip near 5000rpm..the boost dropped of to appx 5psi from 7.

Full boost is reached IMMEDIATELY in a Twinscrew Supercharger/positive displacement supercharger as seen in my dyno run below.

Full boost is reached at or near max engine rpm with a centrifugal.

http://members.rennlist.com/v1uhoh/DynoRun1at7psi.mpg

http://members.rennlist.com/v1uhoh/DynoRun2at7psi.mpg

Right click and save as.

My foot goes to the floor, my boost gage goes to 7psi...as if they were physically connected...unlike my tires to the asphalt when that occurs

Some folks were having trouble viewing the video on the 928 forum...sorry if that is still the case. It is MPEG2 and i guess some folks dont have the CODEC?? or something to play it?



Info on a Twinscrew kit can be found here...
http://www.928supermodel.com

When it hooks up it is a sub 5 sec car.


...FYI, "Roots Superchargers" are old old school and very inefficient compared to the "twin screw" types out today. Granted they work and have for ages..but there days have come and gone IMHO. I think many use the word "roots" like the word kleenex in decribing a postive displacement supercharger.

Rich Sandor

I would have expected a supercharged 5L v8 to be making more than ~375rwhp/rwtq . why not turn up the psi???

A 2.5L i4 w/ a properly sized compressor/turbine and appropriate chips (and exhaust and intake mods) can make that much at a safe 18psi. Why not turn up the boost on a supercharger? Are they limited in some way? I thought you can just change the pulley.

I admit i don't know as much about supercharging as I do turbocharging.. but i'm learning thanks to this thread. so excuse my questions if they seem dumb.

inactiveuser92616

hmm, as far as the turbo running cooler than the supercharger, I think it depends wholly on which units you are comparing. This is all about the adiabatic efficieny of the compressor. A well designed centrifugal supercharger has the potential for cooler temps because the turbocharger would have some heat soak. Look at it this way, you could have the exact same compressor wheel and housing on a centrigual supercharger as on a turbo, the only difference would be their power source, one is belt drive the other is exhaust driven.

All that said, I highly favor a turbo setup as it takes advantage of the high quality exhaust energy, turning it into increased engine efficieny and power. Any other application just wastes that energy.

BC

Tony is simply in innitial tuning stages, feeling out his air fuel ratios, etc. He'll probably answer, but he'll be turning it up soon. Like he said, with so much at like 2k, there is alot of traction issues as opposed to power comming on at 3k or 4k SOFTLY. I have this feeling there is nothing soft about the torque from 7psi on a 5l v-8 at 2k.

theedge

I got the fun experience of driving a supercharged Toyota Tacoma. Supercharged V6 engine. The thing makes in excess of 300ft/lbs of torque at about 1500RPM. Nail the gas at a stoplight, and youll just kinda sit there spinning the huge tires. Put in 4WD then nail the gas, and its like being rear ended by a speeding train, your neck hurts afterwards. BUT its pickup in the higher RPM wasnt as impressive as the low. I think a 5L V8 is going to be gut wrenching once tuned

Rich Sandor

I can imagine. I know that with no LSD, a measly 240rwhp can be trouble on 8" wheels.

375rwp even with lsd should have no problem breaking loose even 10" rubbers.

theedge

The main barriers to just throwing on a bigger pulley are the RPM limits on the supercharger itself (its gearbox and such) and then like turbos, it has a limit before it starts huffing some seriously hot air. This is from what I know/have read.