I performed a search.."pulley and dyno", but didn't find an answer...has anyone dynoed their car before and after adding only an Unorthodox main drive pulley??

Has anyone dynoed there car before and after the addition of any pulley kit? i.e. with no other changes

thanks, Dave

 

I did about 6 years ago. I think it was 15 RWHP from adding the main pulley.

Jason

 

Really! I thought that the rwhp increase was barely noticeable...

Ok, so which set works with the AirPump?

 

You can use either just the main pulley or do the full set.
I was shocked by the results also, but we didnt change anything else on the car.

Jason

 

I can't believe my eyes...I read somewhere (so you know it's true) that disconnecting all the belts on one car netted only about 3 extra horse...

I was going to do the same (dyno without the belts to see the dif) before installing an underdrive main pulley...

now I'm stumped...any other testimonials....

thanks Jason

 

Just remember to leave your water pump still hooked up You might need that.

B

 

The Unorthodox pulley actually frees up "a lot" of weight on the eccentric shaft as it's lighter than the stock pulley.

The complete Unorthodox kit gave me a 18RWHP increase.

 

Is there a torque loss to this??

 

 

are there any negatives to installing a pulley kit?

 

18 hp??? Dang, I need to see more info on this. Personally I don't believe it.

 

I don't either. Less rotating weight on the main pulley/eccentric shaft contributing to increased hp? All that would do is increase acceleration (and even then, it doesn't spin fast or quick enough relative to its small diameter for rotational inertia to have much of an effect). With all due respect to Jason, I find it very difficult to believe that the RX-7 suffers from 15-18 hp worth of parasitic drag (unless your engine was putting out over 600 hp, but then I'd figure you'd jettison the air pump and maybe the PS pump by that point, which would cut drag by probably at least half). I'd think that the belts would fry from the load/friction if that were the case.

 

I have a trailer hitch on mine and put one of those spinning propellers on it. I netted +23 RWHP.

 

Tomco78......was the underdrive pulley the only change you made between dyno runs???

guys, if I do remove any belts for the dyno check...it will only be the power steering/ac belt

 

On unorthodoxs old website they had a couple of cars that made the same HP after adding just the main pulley. It will free up HP, the question is how much.

Jason

 

The only problem with the UR pulley is the removal of the eccentric shaft bolt (hard as crap to get off) and some bearing in there falling out of place (rare but has happened). I've seen a couple dyno sheets with just the pulley done that back up what Jason saw on his car.

Tim

 

How did you guys get the eccentric shaft bolt off, and more importantly, how did you put it back on within torque spec. according to the shop manual, its 490 Nm!

 

I remember a dyno a few years ago that was 12 rwhp higher after the UO main pulley install

 

My question is if you are underdriving your accessories, are you affecting the efficiency of the water pump and it's ability to cool the engine? Same question regarding the alternator and charging the battery/ignition?

 

Power Tools

 

i put the full set on my car about a week ago. But could not test it out cuz my clutch started to slip but im fixing that this week so ill let you know

 

...SO...what are the downsides to doing the pulley swap?

 

You typically have to use a breakrbar to get that nut off. Air tools will not do it.
You will need to lock the flywheel in place before removing the nut.

Jason

 

Won't any of the UD pullies that don't reqire the removal of the eccentric shaft bolt free up the same HP?

 

Only the main pulley is a different diameter to slow the accessories. The w/p, p/s and alt. pullies are the same size and mostly for show - not much weight difference.

I'm using the full pulley set with no air pump so had to use a Greddy w/p pulley for belt contact purposes. I have no alt. charging problems, cooling problems at idle or belt slipage at high rpm - this is using Evans in a Koyo rad and CWR dual oil coolers. Sorry, no dyno comparisons.

Jack