Which Supercharger?
 

For a Coyote + stock 6 speed auto trans?

My original plan was a Roush kit. But, I'v had an unusual amount of free time lately, and starting to re-think that. I'm considering a Pro-Charger. Lots of things I like about the centrifugal over the roots type.

My question is, will it fit? Has anyone installed a Pro-Charger? Which brackets did you use?

I don't think they look as cool, but they are efficient. I prefer a Kenny bell charger. They make the most power and have many different sizes.

Rumor has it that the centrifugal chargers are more efficient, and run cooler. The roots type appear to be easier to fit in a small compartment. But water-to-air intercoolers are also less efficient.

But, I also like the look. And I want something visually different.

I also like the look and fit of the Paxton - and the history is good. But they don't have a program for the automatic transmission.

Whipple too. You can get a Coyote compatible Whipple from Ford Performance Parts including the tune, although it's probably oriented towards the Mustang it'd be a starting place for your local tuner.

Heat soak can be a problem but you have to run them really hard for that to happen.

A roots style blower is considered a positive displacement blower. It is not 100% efficient because there is clearances between the rotors. There are some designs where they put Teflon on the rotor tips to seal better.

A centrifugal blower is not positive displacement. At a zero delta pressure they move a ton of air, but as the delta pressure builds the air flow will drop all the way to zero. The pressure that the blower can build is proportional to the tips speed of the fins. Therefore the faster you spin it the more pressure it can push. On the other hand, the slower you spin it, the less pressure it can push.

On an engine, a roots style blower is moving a certain volume of air per revolution. The engine displaces a certain amount or air per revolution. If the blower is moving about twice the amount of air that the engine is ingesting, the pressure will be about 2 atmospheres, which is about 14.7 psig. So at any rpm, the engine will get roughly the same amount of boost.

On a centrifugal blower, at low rpm the blower cannot make much boost at all. If memory serves it is a square function curve. So, let's say you can make 14.7 psig at 8000 rpm. At 1/2 that (4000 rpm) you can only make 1/4 the pressure (3.7 psig).

Full out both blowers will perform the same. Down low, a centrifugal is like having no blower at all.

A roots style still has slippage (losses) and that does make heat. At pressures less than 10 psig it is not worth considering. However the twin screw compressors out there are much more efficient. They take less power to turn and make less heat. If the price was similar, I would go twin screw compressor every time and twice on Sundays.

PS
A positive displacement blower will give you a nice flat torque curve.

A centrifugal will give a torque curve that looks like the right half of a "U". If your cam and heads quit breathing fairly quick, the two will combine to give a curve looking like "/ " (only a little flater).

Yes, I see what you mean. I like a nice flat torque curve. Very easy to drive, and very predictable.

http://www.allfordmustangs.com/forum...g_graph_02.gif

Roush it is! Thanx. That was my original plan. But you know how it is when you get too much free time.

The other thing I noticed is how fast the centrifugal spins. About 5 times engine speed, or so.

There seems like there'd be room for turbos. I bet Hellion could put together a potent system. They can package twin turbos in Mustangs. They should be able to package them in a Cobra. That would be my power adder.

Either one in these cars turbo or supercharged is crazy fast. With a coyote and small turbos it can make 700hp easy.

Whipple is a better unit and has a nicer inlet location for fitting in the Backdraft especially when you are trying to fit it with a big automatic attached. We were hoping they would release a DBW center feed at some point but have not heard anything.

Isn't the Whipple a twin screw compressor technology?

The Roush kit looks very good. And (more importantly) have an excellent reputation for tuning.

I looked at the new Edelbrock kit. And there's a lot about it that I like. But, the power levels were significantly lower than Roush, and their tuning for automatics might not be as good.

Then I looked at Brenspeed. With their tuning and mods, power levels are about the same (600+), and they have a good tune for the automatic. It's also shorter than other kits, and will fit under the stock Mustang strut tower brace, when others will not. At the moment, my current pick is the Brenspeed Edelbrock kit. I also like the way it looks.

Yes and they are impressive.

Ed

Bob,

Whichever blower you decide to go with, please don't settle for a canned tune from the manufacturer. Take your car to Elite Performance in Denver and have them tune it for you. One of the mechanics there is a Backdraft dealer and knows Cobras inside and out. The tuner has done several Cobras including a blown/nitrous Coyote Backdraft car.

You're exactly right. The canned tune is a good starting point. But if you want the best drivability and performance, it needs a little dyno time for that last 5-10%. I'll take it over to Lou's Cars and let them do the final bits for me.

Worth watching - Weiand Roots-type vs. Paxton centrifugal. Both used carburetors, and that created some issues with the Paxton blow-through. [ame]https://www.youtube.com/watch?v=EHg2uqJvLOk[/ame]

Summary:
Roots: More torque and HP at lower RPM, lower overall torque and HP
Centrifugal: Lower torque and HP at lower RPM, higher lower overall torque and much higher peak HP

Worth noting: belt slippage issues with both setups, though they seemed a bit of a bigger problem with the Roots-type blower.

Either way I'd go EFI, and FiTech has power-adder and blow-through configurations that would be worth looking at.

Can make anything fit with little work, I now have the kennebell 4.2 LC on car.ive seen the coyote motor with KB on it. Car ran very well.
http://i1383.photobucket.com/albums/...ps7v3f1dxs.jpg

That's Lou's Cars, in Littleton. Lou Rivera "retired" some years ago, and only works on fun cars. Last time I was there, he was busier than ever! Come on, Lou, time to retire. :)

Elite Performance is a tuning company with one employee, and I can't think of his name right now. Lou tunes the carburated cars, and Elite does the EFI stuff. He's pretty darned good, too.

In the end, I went with Edelbrock from Brenspeed. Mostly because they have an excellent tune for an automatic car. But also because the inlet is in the front of the blower, and not the rear. The rear inlet may be more efficient, and make a little more power. But this one fits better. I'm not looking for ultimate power. If I was, I would have used a stroker small block Windsor. :)

http://i13.photobucket.com/albums/a2...psnrmk8pce.jpg

IMO: Any technical discussion on which system is better is kind of silly when considering the car it will be going on. Your not picking a work truck or wife. Which one makes you giggle more? There is your answer.

I have retired twice. I work more now than when I worked as a job. I think it's in your blood :3DSMILE: