Anyone using a wastegate or 10lb pulley with their Paxton and a stock motor?

[pumpgas]

I was reading an interesting article about using a wastegate (like the turbo guys) do to control the amount of boost a centrifugal supercharger can make. This way you can go down to a smaller pulley which will allow the boost to build much quicker but use the wastegate to control the overall boost level to keep it at a safe # for a motor with stock internals.

I figure if you used a pulley setup that would normally maybe make 12-15lbs of boost and then bleed off 5-6 lbs. of that so that you were hitting say 6-7 lbs. at 3,000rpm or so and then 8-10lbs at 4,000 rpms and then use the wastegate to hold that constant through 6,000 rpm. This would make the Paxton feel more like a positive displacement blower. The car would most likely accelerate much harder as the average torque and hp would be much greater throughout the rpm range.

Also, the power dropoff you see with a Paxton'd SRT with the stock geared rear would be much less during shifts as well. I know with mine the rpm drop off is significant enough to lose a couple lbs. of boost between shifts.
Would need to dump the Paxton boost referenced fuel delivery and split second box and get some injectors and a custom tune, but for the cost, I think the gains would be worth it.

Hopefully maybe someone has already done this, or knows someone who has. This is a much better option that using a diaphragm in the intake to regulate top end boost like some of the vette shops do.

 

[GTS-R 001]

Email or PM Dipapa,

That his what he had on his before it blew his engine.

 

[britospeed]

This works fine. The only issues to deal with are the increased IAT's from compressing the air more over you baseline boost. The other issue is you'll have more hp loss from running the supercharger harder. On pump gas you'll see boost sooner but you will make less hp at your target boost pressure because of the 2 previously stated issues.

 

[GTS-R 001]

I had a smaller pulley on my paxton and here is what I found

Yes, the paxton made more boost sooner which resulted in more power sooner but

inside the paxton compressor, before the pressure could be released by a BOV, the compressor got hotter because max boost was made at a lower engine speed, boost still increased as the rpm went higher and this superheated the air compared to before the smaller pulley was added so Intake Air Temperatures became and issue and more heat soaking happened vs before as well. The horsepower increase was not as great as expected as the air temp was so high (higher compression rate and friction = less horsepower) , also the belt slipped a lot and the front of the crankshaft eventually spun right off due the stress of the smaller pulley. And that was on an exotic Engines built engine and the peak HP it ever made was 830 RWHP with a safe DC tune, other tuners are known for getting more out of a paxton but I am sure those were very lean tunes that are pretty much grenades waiting to explode,

 

[VIPER R]

I wonder if water injection would help?

 

[britospeed]

Water injection would help with the IAT's but you still have the added hp loss from driving the blower faster. A 50% methanol/water mix would be better that just water if your inclined to try it.

Turbos are the better solution in my opinion.

 

[RECOIL]

Got a 10lb on my stock motor; so far so good (but almost never really "get on it"). Might beef up the internals next spring.

 

[mbccenter]

I am running a 12lb on a built engine. Instant power with no lag. With the larger heat exchanger I do not have a heatsoak issue on the street. The belt slippage is more and needed a DLM tension kit. I would think your idea would work well but you would want to keep an eye on iat with a stock engine. Mine did 1002rwhp on A&C's dyno.

 

[pumpgas]

Thanks guys. RECOIL, do you have a custome tune with the 10lb pulley, or are you using the paxton FMU, split second and additional fuel pumps?

 

[Seb]

You guys are making it sound like your getting a increase of 100 degrees in air temp. Its not like your going from a 7 lb pulley to 28 lb pulley. We have been doing this kind of control for many years with great results.

From the data Ive seen minimal air temp increase with a couple psi pulley change. It be a different story if we are talking a f2 procharger which we are not.

 

[RECOIL]

I have a custom tune, DLM cooler & tensioner, VEC 3, second Walboro in-tank fuel pump, Belangers, Corsa and cat delete.