[Elarson]

There's a back-and-forth on roots superchargers in another thread. Thought I should start a new thread. The discussion was about efficiency which made me recall a fun fact.

The John Force organization owns somewhere between 30 and 60 blowers. They run each one once and then set it aside to restrip it. That way, they have as near as possible exactly the same efficiency every run.

I can say from experience that they are very tight when freshly restripped, but loosen up with use. Since we don't have the JFR budget, we base our tuneup on the looser, broken-in condition and don't restrip unless we have to.

Eric

[PAUL K]

Very interesting.

[GTOGEORGE]

Good thread, every blower is not created equally theres teflon strip blowers......non-teflon stripped blower, 60 degree helix rotor blowers, 120 degree helix rotor blowers.....etc. some of the pros have dynos just for the blowers......there's a reason!


GTO George

[Elarson]

Both of our blowers have been on the blower dyno at SSI in Cleveland. Great company to deal with.

Eric

[Tom Vaught]

The fact that John Force KNOWS that the efficiency changes after every run tells you that he knows you can't predict supercharger efficiency accurately from run to run, much less over a season of runs. Something the Blower manufacturers have known for years.
Eaton, Whipple, Lysholm, will all tell you the same thing. They give you a ball park number. Despite what some assume.

Tom V.

[GTOGEORGE]

Originally Posted by Tom Vaught

The fact that John Force KNOWS that the efficiency changes after every run tells you that he knows you can't predict supercharger efficiency accurately from run to run, much less over a season of runs. Something the Blower manufacturers have known for years.
Eaton, Whipple, Lysholm, will all tell you the same thing. They give you a ball park number. Despite what some assume.

Tom V.

Wasted post......just to hear yourself talk! LOL!


GTO George

[twooldgoats]

Originally Posted by Elarson

...

I can say from experience that they are very tight when freshly restripped, but loosen up with use. Since we don't have the JFR budget, we base our tuneup on the looser, broken-in condition and don't restrip unless we have to.

Eric

The good news is that as the strips wear and the blower moves less air, the tune becomes richer. Running methanol, as I do, that isn't a problem and should be picked up by EGT numbers, etc. after the pass. Then, the tune can be adjusted accordingly.

Jm

[GTOGEORGE]

Originally Posted by twooldgoats

The good news is that as the strips wear and the blower moves less air, the tune becomes richer. Running methanol, as I do, that isn't a problem and should be picked up by EGT numbers, etc. after the pass. Then, the tune can be adjusted accordingly.

Jm

I don't notice any wear on my blower through out the year, still can't get my egt numbers down but everything seems to be working ok.



GTO GEORGE

[Tom Vaught]

Originally Posted by GTOGEORGE

I don't notice any wear on my blower through out the year, still can't get my egt numbers down but everything seems to be working ok.

GTO GEORGE

"still can't get my egt numbers down" says it all.

Even with methanol fuel, you have no clue how to control the combustion temperatures in the engine. You are too hard headed to listen to me.
Why don't you call Travis Quillen at Quillen Motorsports and have HIM explain to you how it works, George, with methanol and egts.
Travis is an outstanding tuner.

Tom V.

[GTOGEORGE]

Originally Posted by Elarson

Both of our blowers have been on the blower dyno at SSI in Cleveland. Great company to deal with.

Eric

So what Blower dos you have on your RA5 set up?


GTO George

[Elarson]

SSI 14-71, standard helix. We bought refurbished used ones so they don't have any of the gee-whiz latest stuff. Just ordinary old school stuff in great condition.

Eric

[GTOGEORGE]

Originally Posted by Elarson

SSI 14-71, standard helix. We bought refurbished used ones so they don't have any of the gee-whiz latest stuff. Just ordinary old school stuff in great condition.

Eric

Why not a High Helix one with 120 degree rooters?


GTO George

[Elarson]

One of our advisors a long time ago told us that nitro and high-helix don't play well together. We haven't investigated further to know if that was accurate or an old racer's tale. Turns out that the standard helix was readily available on the used market and we have a good tuneup now based on std. helix. So no changing now.

Eric

[GTOGEORGE]

Originally Posted by Elarson

One of our advisors a long time ago told us that nitro and high-helix don't play well together. We haven't investigated further to know if that was accurate or an old racer's tale. Turns out that the standard helix was readily available on the used market and we have a good tuneup now based on std. helix. So no changing now.

Eric

Thanks!

GTO George

[Elarson]

Are you switching to high helix? Why not just run your existing one a little faster?

Eric

[GTOGEORGE]

Originally Posted by Elarson

Are you switching to high helix? Why not just run your existing one a little faster?

Eric

I'm about 27 over right now. Haven't decided what I'm doing yet, tossing some ideas around.

GTO George

[twooldgoats]

Originally Posted by GTOGEORGE

I'm about 27 over right now. Haven't decided what I'm doing yet, tossing some ideas around.

GTO George

While you're at it, consider mechanical injection--port and hat. It will make your life much simpler.

Jim

[GTOGEORGE]

Originally Posted by twooldgoats

While you're at it, consider mechanical injection--port and hat. It will make your life much simpler.

Jim

Ya I know..........probably go quicker too BUT its always a money thing!



GTO George

[Torment]

If you're fueling adequately with carbs at your current OD I'd be surprised if you went faster with injection. If you step up the blower I think you'll find the injection to more reliably provide the fuel needed.

[Torment]

Originally Posted by Elarson

There's a back-and-forth on roots superchargers in another thread. Thought I should start a new thread. The discussion was about efficiency which made me recall a fun fact.

The John Force organization owns somewhere between 30 and 60 blowers. They run each one once and then set it aside to restrip it. That way, they have as near as possible exactly the same efficiency every run.

I can say from experience that they are very tight when freshly restripped, but loosen up with use. Since we don't have the JFR budget, we base our tuneup on the looser, broken-in condition and don't restrip unless we have to.

Eric

One of the advantages of a screw is a more linear efficiency within a run as well as week to week. No strips to heat up, no strips to wear out.