Allen Superchargers

They finally released the 2V kit? ARGH!!! I waited 2 years and got tired of the endless delays. Went with a centrifugal 4 months ago. It definitely doesn't have the bottom-end grunt that I long for. (but it comes on like gang-busters up top) __

John "I want a Whipple" C. '00 GT Convt. '03 Cobra Convt.

the endless delays.

bottom-end grunt that I long

You're going to feel even worse when you see the dyno graphs on Kenne Bell's web site for the GT kits. The few kits that have been dyno'ed so far meet or exceed the numbers KB claims. Here's a link to their site:

Keep in mind that all but the 14 psi numbers are on bone stock GT's. There's a guy that is making 437 rwhp on just 9 psi with a stock exhaust and a few inlet mods. This kit gives me a good reason to start looking for a '99+ GT convertible.

Yep, I feel worse.... : /

Those are REALLY impressive numbers. And those were run at an 11:1 a/f ratio,.. damn. Kenne-Bell is the torque monster on the block. Looks like a very well engineered piece, too.

Kickin' myself now. I should have waited just a _little_ longer... : ( __

John C. '00 GT Convt. '03 Cobra Convt.

ratio,.. damn. Kenne-Bell

I've had a KB on my '89 LX for years and really like the torque it produces. I would kill for an intercooler as efficient as the one they put on these new GT kits. I bet an intercooled kit pushing 10-11 psi with full exhaust, inlet mods and ported heads would be close to 500 rwhp. The trouble is I doubt the stock rods and pistons could take it though. I can't wait to see one put on a forged short block with an

8.5-9.0:1 compression ratio, ported heads and blower cams at 14+ psi.

Woohoo the the Ford Gods have finally blessed us late model GT owners.. thankyou Edsel who art in heaven! MustangsandFastFords does an install and dyno runs in the October 03 edition.... ohhh mamma!!! From the look of it and the info on the KB wetsite theres nothing missing from the kit..

I have been in contact with a VERY knowledgable installer about the Kenne Bell vs Allen supercharger question. I decided I would rather have the Allen supercharger. Below is his reply to me for those who are interested. - John

Kenne Bell vs Allen Supercharger (6 psi systems)

I would not expect much more hp (from the Kenne Bell). Yes, it is more efficient (75% versus 60% adiabatic) and yes, it will have slightly lower discharge temps. However, that is not lower than the Allen with an intercooler. I suspect the power output is somewhat similar but the Allen still has a much better intake design and the intercooler. The temperature entering the cylinders will still be lower with the Allen. KB uses the Autorotor compressor which is a good unit but it does not even compare to the Eaton for quality and reliability. I had to replace one for noise and I had a second that was even noisier. I have never seen the Eaton fail in any way and they come factory on many cars from companies like Mercedes, Jaguar, Aston Martin, Ford, GM, and the list goes on. I am not away of a single major auto manufacturer using the Autorotor. Also, the screw builds pressure internally at all times which drives more parasitic loads at cruising speeds, wasting more gas. The Roots draws less that 1/3hp at cruise so you retain your fuel economy. The bypass valve also helps with the parasitic losses and keeps the unit cool when not in boost.

On a scale on 1-10, 1 being paxton (piss poor),

Allen scores a 9.5 for product support. Kenne Bell scores about a 7.

Reliability: Allen 9.5, Kenne Bell 7

Driveability: Allen 9.5, Kenne Bell 8

Kenne Bell is a good product and a decent company to work with. Allen is just much better. Both are far better than any centrifugal.

I have to question this installer's knowledge regarding superchargers. Nearly everything he told you about twin screws verses Roots blowers is dead wrong.

A KB kit will make much more hp than a Roots at any given psi of boost. Allen's website lists the hp output on a Mustang Bullit from their 9 psi kit at about 340 rwhp. A guy on Stangnet had the 9 psi KB kit installed on his Bullit and made 437 rwhp through the stock exhaust. Now I would say that is a substantial difference in power output.

Root's blower's efficiency can go as low as 50% at higher boost levels. The difference in efficiency between a Roots and twin screw mean lower discharge air temps and less power needed to turn the rotors. This means more power is available at the wheels.

The KB intake design is very efficient or it wouldn't make the huge hp numbers from so little boost. The KB kit can be had with an intercooler too. Why would the Allen kit have lower temperatures than the KB?

The twin screws are manufactured to higher tolerances than the Roots blowers. This is why they typically cost more. The twin screws are every bit as reliable as a Roots. Twin screws are also just as quiet as a Roots. BTW, has your friend seen what blower Mercedes is using on their newer blown cars? It's a twin screw. Also, the rumor is that Ford will use twin screws on the Ford GT, new Lightning and the '06 Cobra. If you want to see a good comparison of the two types of blowers look at the hp increases that are had from swapping the Roots blower on the Lightning and Cobra to a twin screw. The Cobra makes 600+ rwhp from just a blower swap with the stock exhaust. It can also run up to 25 psi of boost where the stock Roots is lucky to make 15 psi.

The main reason they aren't OEM is their cost. Mercedes has been using them for awhile. Your friend acts like compressing the air inside the blower is a bad thing when it is not. This is what makes the twin screw much more efficient than a Roots. The KB has a bypass and it takes very little hp to turn them under non-boost conditions also.

KB's support isn't the best but their 4.6L GT kits are top notch. I would rate them about a 7 or 8.

I might give a slight edge to the Roots because it has to operate under less tight tolerances. The spread isn't this wide though.

I don't understand how one can be more drivable that the other unless the KB is penalized for making too much hp. They both deliver power in the same way.

When comparing the 4.6L GT kits I don't see how the Allen can be better than the KB. It might be less expensive but is doesn't deliver close to the performance of the KB. As for whether either one is better than a centrifugal that is totally subjective. Power wise a centrifugal will stomp a Roots blower. Centrifugals are proven performers and if the person likes their power curve are a great choice.