Herr-Kuhn

As I start down the 928S4 twin turbo path I have been gathering much information regarding components, designs, expectations etc. I have a lot of work cut out for me, but in the end I believe I will have the best forced induction setup for the 928. Street manners, stock fuel efficiency as well as power when you want it. All of this wrapped in the sleek egg-like shape of the 928!

I found this website some of you might be interested in taking a look at. Check out the video of the 4-door turbo M3 simply demolishing the 360 Modena. Turbo power is hard to beat and that video is simply awesome. Lots of boost there for sure and I don't know if I buy the 1000 HP claims or not, but still it is very impressive! Listen to the shifts, you can hear the blow off valves working. Note the simple exhaust manifolding!

http://www.da-motorsport.com/

Is 1000 HP possible with the 928? My bet is the block would never handle these power levels. My HP goals are realistic with this build, but time will tell the real truth. I do know I'm gonna need an LSD for my trans.

chris0626

Excellent! Although I'm gonna call BS with no dyno sheet. 1000hp? Is that at the wheels or the crank (and if its at the crank, is it real or estimated?)

[RANT] I'll never understand why anyone even bothers with 'at the crank' estimates... it's what's at the wheels that gets you down the road [END RANT]

It's gotta be an estimated at the crank #... still, very impressive. I wonder how long that block will last at 30psi (iron or not, that's a lot of pressure).

Cast iron manifolds are best (retain heat and are strong) and the design is simple.

TURBO's rule! Your project is gonna be great.

I think a LSD is a given, you should be able to push 475-575 at the wheels, with the right tuning & pressure. Didn't someone say that the trans was the weak link above 600?

Jim_H

We'll see. The SC'd 928's work quite well, have no heating issues and are inexpensive. You have claimed the turbo is superior often. I would have liked to have seen a dyno of your last project but for some reason that wasn't to be. So, another claim of turbo superiority, maybe, we'll see.

Fabio421

Are you planning on beefing up the transaxle or torque tube? I have heard people here say that the transmission cannot handle above 600 hp.

Edit: I see someone beat me to the 600hp question. Its nice to see we ae all on the same page. I just need to type faster and stop watching those videos. LOL

m21sniper

"The possibilities with Turbocharging"

The term 'limitless' comes immediately to mind.

Video of a 1000rwhp(with tires smoking!) street driven Buick V-6 twin turbo Grand National on the dyno:
http://fasttrackperformance.com/page.../ChrisTTGN.wmv

MarkRobinson

I should be able to dyno my turbo 928 later this week...waiting for temperatures & time to work to my advantage. 108 here yesterday! good grief! That plus a full tank of 87 octane (due to the hurricane-scare) is keeping me from hitting it sooner.

m21sniper

Jim H- "we'll see. The SC'd 928's work quite well, have no heating issues and are inexpensive. You have claimed the turbo is superior often. I would have liked to have seen a dyno of your last project but for some reason that wasn't to be. So, another claim of turbo superiority, maybe, we'll see."

Turbos are clearly superior wrt power vs parasitic loss. That's not an opinion, it is scientifically proven fact.

There is a reason Porsche uses turbos and not S/Cs afterall.

Jim_H

I have no problems with that.
I do question "the best set up for a 928" claim. This includes more than just power, imo.

JEC_31

I've seen some of DA's older videos, running a SC'd E36 M3 against a F360 somewhere in the Middle East. Big ***** on that car, it doesn't surpise me that they're moving up.

The heavy inline 6 in those cars responds extraorinarily well to forced induction, as it is very well balanced and fairly overbuilt for stock (infamous crankshaft quality issues aside LOL).
Don't forget, inline-6 is a "naturally balanced" design with no secondary order vibrations, V8 is not.

My take on the Big Debate:
It's pretty much self-evident that Turbocharging holds the edge in overall efficiency, as the power spent spinning a large compressor with a belt is measureably more than the power spent spinning small compressor(s) with exhaust pressure. With that in mind we then compare all other aspects of design, cost, and installation - this is where the Supercharging leaps ahead in viability.
And don't forget the magic cockpit-mounted boost-control **** - no SC has that (Mad Max's movie-magic design aside LOL)

Random Thoughts: How much boost can the open-deck block take? And how much HP/Torque can the rest of the drivetrain stand?

I say build it Herr-Kuhn!

m21sniper

"And how much HP/Torque can the rest of the drivetrain stand?"

That's really a bit of a loaded question i think. We always seem to hear 600hp(rwhp?) reported for the driveline max, but is that at ilde, or at 4000rpm?

If the car is already doing 40mph when the 600hp threshold is exceeded it will cause a lot less stress on the driveline than if that power level is delivered on launch, just off idle.

Which is another edge to the turbo/centrifigul SC vs the roots/twinscrew types. The latter deliver full boost shortly after idle, whereas turbos/centrifiguls bring the power on at much higher RPMS. This is IMO an advantadge for two reasons:

1) reduced instantaneous driveline shock on the system when launching
2) Increased launch traction

Jim bailey - 928 International

JEC..."And don't forget the magic cockpit-mounted boost-control **** - no SC has that (Mad Max's movie-magic design aside LOL)"
OK how about this .".The McCulloch blower has a “variable-speed drive” that allows it to mark time until you open the throttle all the way. This is operated by engine manifold pressure and thus gives you maximum power only when you need it for passing or hill-climbing. Most of the time the engine acts just the same as it would without the supercharger. " This factory installed blower option was available in 1954 on a standard production car in the US.

TAREK

The early 80's 3-series blocks handled 1200 hp in Nelson Picket's Brabham BMW F1 racer, for at least the entire race....say 90 minutes. Don't know the difference between that block and the current 3-series blocks, but if it's anything like it, it should be good for the street with occasional spirited driving...No?

bcdavis

I think, other than cost, the reason people like the idea of superchargers,
is that the 928 seems weak off the line, but strong in the upper range.

Hell, my 83 euro seemed plenty fast at the top end.
Enough to beat most cars on the freeway.
But it was a dog down low.
That's why a supercharger is appealing.
Because it boosts the low-end launch power.

Tony

Boy any more chest beating like this, you may have to become a sponsor at some point when you start selling them.

Hopefully the new owner of "The Member" will post a dyno sheet?
Better hurry as the rear turbo folks are well on there way

mspiegle

That E36 M3 may or may not be BS. Nobody is certain... The motor has the revlimit uncapped to about 8000, lots of little mods, and 36psi of boost. If you work the numbers out, based on hp increases per psi of boost, the car could have 900hp+, but that's in a perfect world. Chances are, the car makes 700-800 at the flywheel.

You guys can go on bimmerforums and read the entire thread about it. I dropped some math into it and defended the owner because all those BF idiots can do is chime in the thread and say "WHAT?! THAT'S IMPOSSIBLE". Even though I don't necessarilly agree with his 1100hp estimate personally, I think 99% of the people who commented on that thread don't know jack **** about forced induction and they shouldn't be talking.

If you can't tell already, uneducated kids are a pet peeve of mine...