Bosch Pump & Stepper Pulley

[zip]

Can you guys explain or provide me a link on what a stepper pulley is and how it works? Thanks.

[ringer]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by hooper:

As far as raising the boost, my ENDYN modded JRSC runs 15 psi without problems. <HR></BLOCKQUOTE>
Have you got any dynos or 1/4 runs on that puppy?

[SC HYBRID]

ENDYNE sells an upgrade for the alternator pulley that replaces it with a bigger one,which in turn produces more boost,approx.8-9 p.s.i.

[green95gsr]

TurboGSR is completely correct at least in theory. In practice, I know that the Miata guys here in Atlanta (and anecdotally in other places) have tried the 8 psi upgrade and a number of other tricks including water injection to raise the boost level of the JRSC. Now, in the Miata it is actually physically possible to put an I/C between the blower and the dummy TB so that has been done too.
The results of these attempts were less than satisfactory. Still the most powerful JRSC Miata measure among 6 or more at a dyno day was a stock, 6 psi 1.8l Miata, followed clodely by another 6 psi JRSC Miata.
I don't know why this is or what the problems are but the fact is that the 6 psi JRSC seems to be the magic number for best performance with minimal hassle.
I know that many GSR guys have 8 and higher psi JRSCs and I don't doubt that they make a lot of power, etc.
Personally, I believe that the 6 psi system is best and when properly tuned will make very nice power. I believe that the porting of the blower, manifold and head will produce excellent power gains and will allow the blower to flow more air at even lower rpm. This is the secret of S/C performance. Actually, higher indicated boost might not be a good thing!! High flow of non-compressed air is the best thing. Compressed air gets awfully hot and this leads to all types of problems. I would like to have my system ported and polished by somebody who knows the tricks. Ideally I should like to see 5-6 psi with a lot of dyno recorded power

Manuel



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'96 GSR, JRSC 6 psi, Greddy Sp, Apex 4-2-1, Home made CAI w/K&N, Ground controls coil overs, Eibach, AGX, DC short shifter, more stuff on the way....

[zip]

So its just basically a bigger alternator pulley, similar to the one used in SCC?

[fastfour]

Zip,

Don't you mean smaller pulley in order to spin the charger faster for more boost?

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94 Civic Coupe/LS Hybrid
AEM CAI
DC 4-1 Ceramic Header
Random Technology Cat
GReddy PE exhaust
Skunkworks Coilovers
ACT 6 Puck
Turbo Convert
Supercharger on the way?

[reddelsol]

I have the Endyn alternator pulley. But haven't put it on yet.

For you civic guys -- my set up will be

1 Unorthodox underdrive pulley
1 jr 3.8 SC pulley (yes, that's right 3.8)
1 Endyn stepper alternator pulley

Hopefully this will make around 7 or 8 psi if I'm lucky.

[Holden]

reddelsol: Sounds like you'll be making a lot of trips to exchange belts!

That's an interesting idea using the UO pulley combined with a smaller blower pulley to cancel each other out. The lower rotating mass will likely be worth a tenth or so on the 1/4 mile. I'd be concerned about no harmonic balancer at our boosted torque levels though.

Greg

[zip]

fastfour: If its on the alternator side wouldn't you need a larger diameter pulley as oppposed to a smaller pulley on the SC? I don't know, if my logic is correct though.

BTW, why do they call it a stepper pulley? Is it because one side of pulley is smaller in diameter compared to the otherside?

[reddelsol]

Yeah, I am concerned about no harmonic balencer -- after reading up on T.O.O comments.

So, we'll see what happens (crossing fingers)

I've been running 5lbs of boost without the stepper puller (no problems so far).

In answer to "stepper" name - well the dual pulley is two different diamenters, so maybe that is why it's called that, but don't know for sure.