Roe vs Paxton For A Daily Driver

Well, I admit I'm confused then.

At any given engine speed, the supercharger is spinning as a function of the rpm, nothing else. Regardless of if I'm cruising or WOT at any given speed, the supercharger is spinning in proportion to the speed of the crank and not on how much I'm stepping on the throttle. Isn't the blower compressing air in proportion to the speed of the spin?

I believe what you guys are telling me (I'm new to the s/c concept), but I don't understand it. I'm missing something very important here and I don't know what it is, but I welcome any explanations (keep it simple :) ) to clear up my pre-conceived notions.

Thanks!
 
With the Paxton you'll be running vacum until you reach about 3000 rpm at which point the boost will really start kicking in. When cruising 1500 rpm I'm running about 10 psi vacum.
 
SRT-MIKE said:
Well, I admit I'm confused then.

At any given engine speed, the supercharger is spinning as a function of the rpm, nothing else. Regardless of if I'm cruising or WOT at any given speed, the supercharger is spinning in proportion to the speed of the crank and not on how much I'm stepping on the throttle. Isn't the blower compressing air in proportion to the speed of the spin?

I believe what you guys are telling me (I'm new to the s/c concept), but I don't understand it. I'm missing something very important here and I don't know what it is, but I welcome any explanations (keep it simple :) ) to clear up my pre-conceived notions.

Thanks!
Click to expand...

I believe that it has to do with how quickly you are increasing your RPM, If you acellerate slowly you do not go into boost. If you accelerate quickly the motor creates boost.

This is how I picture it!!:dontknow:
 
I was wondering. If I get a Roe supercharger, would it reduce the weight of engine because it would remove the stock intake manifold? If I get the Paxton supercharger and would it add the weight because the stock intake manifold is still there or will it be the same? Thanks.
 
SRT-MIKE said:
Well, I admit I'm confused then.

At any given engine speed, the supercharger is spinning as a function of the rpm, nothing else. Regardless of if I'm cruising or WOT at any given speed, the supercharger is spinning in proportion to the speed of the crank and not on how much I'm stepping on the throttle. Isn't the blower compressing air in proportion to the speed of the spin?

I believe what you guys are telling me (I'm new to the s/c concept), but I don't understand it. I'm missing something very important here and I don't know what it is, but I welcome any explanations (keep it simple :) ) to clear up my pre-conceived notions.

Thanks!
Click to expand...

I thought the same thing. I was surprised to see I run around under vacuum all the time unless I get on it fairly hard. If a police officer is following, you will never see boost. Once the engine catches up with the throttle position, it is sucking in its own air. If it is accelerating, it is still being force fed.

This is my rudimentary understanding based on what I observe around town while driving.
 
Contrary to what logic would lead you to believe, the Roe idles until you "get after it". At 80 mph in sixth gear it is turning very little. The boost is a function of the VEC III recognizing the throttle "urging". The same is true of the Meth injection...no meth at normal driving, but push on the throttle a little hard and the meth sprays, and the SC starts to whine...

Someone with more technical expertise will have to give the details, but this is my view from the drivers seat...
 
Ok, got an answer from a local tuner... after hearing it, it seems so obvious, this is how I understand it now:

With the top mount, the amount of boost is proportional to how much air is available for compression (boost). In other words, regardless of how fast the engine and supercharger are spinning, the amount of compression is limited by how much air the SC can suck though the Throttle body.
During cruising a "steady state" is reached where the amount of air the engine is sucking is equal to the amount of air the TB body is allowing through the SC, so there is no "extra air" available for compression (independent of the speed of spin). Then when the butterflies fully open during WOT, much more air becomes available, this air is then compressed by the SC and force-fed into the engine until it reaches "steady state" again at higher rpm. The VEC3 measures the amount of air going into the engine (by sensing the pressure in the manifold) and delivers fuel and Meth accordingly.

With centrifugal SC's the situation is slightly different. While the top mount SC boost is proportional to the amount of air available, on the centrifugal SC the amount of boost is proportional to the air flow allowed by the "backpressure" of the TB, as intake air is practically unlimited. At WOT the backpressure goes down to nothing and compressed air is allowed into the manifold to force feed the engine.

Anyway, this made things much clearer for me, I hope others can benefit from it.
 
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Sorry fellas that have the Roe's...that I have not much chimed in on this... but for good reason... it alway's seemed to get off to a boil and :dontknow: IMHO... we ended up hammering two very good options for forced induction on these motors...regardless. I have had the chance to drive them both...and they are different... but both extremely fun, quick, smooth, and reliable to date.
Hell, the Viper guy's have been running them both longer than the entire production run of our trucks. ;) :rock:
Watched them all run them at various V-10 National's in the past, and upon multiple questions to each driver of the various set up's at those National's.... all the same answers... ask a fella running his Roe, Paxton, Turbo'd, SC & Sprayed...ect... they are pretty happy with either with what they have, or have had built...and were there to improve on it.... and make it to the show:rock:

After my quest for info was complete... it's pretty obvious which route I went...and I am extremely happy with it.... now I am in the same boat as everyone else out there... (regardless what they have) improving my :driver:

If you can make the Nat's... you would have a pretty good opportunity to "drive the difference" and see which one "trips your trigger":rock:

Have fun with it, and good luck.
 
Roe Long Term Test - Act II
Hi Guys
Since we last visited I have put quite a few additional miles on my Roe SC equipped Yellow Fever. I now have 30,000 miles on my truck. Roe and his guys pu the SC on it at 11,000. I have done zero to the engine except change the oil since it has been installed. The only time I pop the hood is for oil changes or to show off the SC. Just got back from my Charlotte shop which is a 4 hour drive each way and often make this trip once a week. Got caught in a torrential downpour this week, no water issues whatsoever. Last weekend I had errands to run in ATL and was in stop and go traffic all day. No issues at all. My sales manager has an Expedition with a Paxton on it and he likes it, but does say the engine has to get up some rpm's before he can feel it working. I enjoy the additional torque of the Roe in daily driving and traffic situations. It makes it easier to change lanes, catch the exit you're about to miss or passing a blue hair doing 25 in a 55 on a curvy mountain road.
Cheers
Barry Grant
 
Demon1 said:
Roe Long Term Test - Act II
Hi Guys
Since we last visited I have put quite a few additional miles on my Roe SC equipped Yellow Fever. I now have 30,000 miles on my truck. Roe and his guys pu the SC on it at 11,000. I have done zero to the engine except change the oil since it has been installed. The only time I pop the hood is for oil changes or to show off the SC. Just got back from my Charlotte shop which is a 4 hour drive each way and often make this trip once a week. Got caught in a torrential downpour this week, no water issues whatsoever. Last weekend I had errands to run in ATL and was in stop and go traffic all day. No issues at all. My sales manager has an Expedition with a Paxton on it and he likes it, but does say the engine has to get up some rpm's before he can feel it working. I enjoy the additional torque of the Roe in daily driving and traffic situations. It makes it easier to change lanes, catch the exit you're about to miss or passing a blue hair doing 25 in a 55 on a curvy mountain road.
Cheers
Barry Grant
Click to expand...

Well it doesn't take me long to connect the dots.:eek: :eek: Barry Grant and Demon Carb's.

So, when you going to make a manifold/carb combination for these things. I hate FI, and having to tune with a computer. :mad: ;) :D
 
Thanks for the report Barry, I've had my Roe longer than you but don't have near as many miles. My results have been exactly as yours, just a lot fewer miles.

Any chance you will be able to join us at the MOPAR Nationals in August?

Roy
 
Demon1 said:
Roe Long Term Test - Act II
I enjoy the additional torque of the Roe in daily driving and traffic situations. It makes it easier to change lanes, catch the exit you're about to miss or passing a blue hair doing 25 in a 55
Barry Grant
Click to expand...

:rock: Amen, brother!!!
 
Where and when are the Mopar Nat'ls. Hate to be so dumb but my schedule is pretty crazy. And I could look into a Badman, our inline 4-barrel setup, for off road applications once we have them tooled, as that's our big project right now. The length of it would give great fuel distribution and a pair of them on a cross ram manifold would be pretty sexy.
Barry Grant
 
columbus,oh august 9-12 u need to make it, awesome time awesome cars. you ought to have a booth up there.
 
Search the site for MOPAR Nationals...there are two or three threads...If you could make it, we would love to have you!
 
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