Twin SN89's

[slownlow]

I might have a lead on another SN89. Anyone ever hook up duals?
Is it possible? I have the room on passenger side to mount it..

Talk me down please :)

[speedytang]

I have used dual units for the past 20 years on project cars and boats. Not a problem at all and with dual VR4 800hp was a easy task. Those with a Ford small block could probably still find a new dual mount, I had one new less than 5 years ago.

[slownlow]

My kit is for and F150 its mouted in front off to right of distributor(passenger side).So If I get another kit for a mustang where it is mounted to the front left (driver side) and fab up some tubing? Does boost double in this type of config? Not looking for 800hp just wow factor and a bit more power if needed.

[speedytang]

You double your CFM but the PSI stays the same. The CFM is what counts when you get a large cam and big ported heads or a large displacement engine.

[slownlow]

Thats what I figured. next winters fun time in garage.

[Michael]

You double your CFM but the PSI stays the same. The CFM is what counts when you get a large cam and big ported heads or a large displacement engine.

I've always wondered what the net effect would be by running twin superchargers. Interesting that only the CFM goes up, but the boost stays the same.

slownlow is lucky, he's running an F150 so no doubt there's enough room under the hood to accommodate twin superchargers. But for those who don't have that luxury, how much would the boost have to be increased by in order to achieve the same horsepower numbers as twin superchargers? I know the SN's top out at about 6.5psi (more for a VR-4), so we'd probably be talking about a newer, higher psi capable blower.

[speedytang]

VR4 is twice the CFM as a 'SN' unit. A VR4 at 14psi can support 750hp and the outlet temperature is less than a Novi 2000 so with things being equal the VR4 will make more power and reduced detonation. The limit of a VR4 was reached in Renegade Ford series because the internal drive could not give more than 18psi before destroying the unit. This is when the Novi 2000 gear drive was manufactured. In the beginning of Novi development many racers not being happy with the power output went against Paxton the sponsor and put the VR4 back on the cars. This is when Paxton went to the series and had the VR4 black listed and it was not allowed to be used for Legal Competition in Renegade. It was even 5 years later and the VR4 was still on the Black List but was finally removed since it was such a old unit that most did not even remember the blower that allowed a Semi-Stock car reach the 9's which was a first for any street car.

[Michael]

VR4 is twice the CFM as a 'SN' unit. A VR4 at 14psi can support 750hp and the outlet temperature is less than a Novi 2000 so with things being equal the VR4 will make more power and reduced detonation. The limit of a VR4 was reached in Renegade Ford series because the internal drive could not give more than 18psi before destroying the unit. This is when the Novi 2000 gear drive was manufactured. In the beginning of Novi development many racers not being happy with the power output went against Paxton the sponsor and put the VR4 back on the cars. This is when Paxton went to the series and had the VR4 black listed and it was not allowed to be used for Legal Competition in Renegade. It was even 5 years later and the VR4 was still on the Black List but was finally removed since it was such a old unit that most did not even remember the blower that allowed a Semi-Stock car reach the 9's which was a first for any street car.

So ultimately, a single VR-4 will yield the same results as twin 'SN' units without the hassle of having to deal with all the plumbing, mounting, and pulley/belt routing. Good to know. Thanks.

But I will admit, seeing two gleaming 'SN' head units under the hood would look pretty sweet!

slownlow, be sure to keep us posted (with pictures) if you do go with twin SN89s.

[slownlow]

Are you selling a SN89 kit. I see pics but no add for sale?

[Michael]

No, I'm not selling my SN89. I just posted some pictures of the kit for the fun of it.

In fact, I plan to rebuild the head unit (it's in MAJOR need of a rebuild) this summer, so I'll probably be posting pictures of the process as I go.

[novasport]

Here is a picture of my 71ss Nova I have been working on. Two SN93 383 SBC Still working on it. Need two 3.75 pulleys for the SN93 and install the idler in the center of the bracket which will slid down to tighen the belt.

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[Michael]

Here is a picture of my 71ss Nova I have been working on. Two SN93 383 SBC Still working on it. Need two 3.75 pulleys for the SN93 and install the idler in the center of the bracket which will slid down to tighen the belt.

WOW! Really nice setup. Thanks for posting those images.

Any idea when you think you'll be done with your project? It'd be great to see the final product when it's done.

[slownlow]

I like it.. I just need to find another one at reasonable price.

[speedytang]

You might find out like I have you will need a Idler to sit on top of the belt running across the top. The harmonics of the belt will make it sound like a banjo when letting on and off the throttle. Also if you don't you will not have enough belt wrap to keep the belt from slipping.

[novasport]

Thanks for the wow There still a lot to do before the car is done. I wish it was done Ive been working on it for two years now. I have owned the car from the time it was new. It set arond for 20 years before I started to restore it. I use to race it before it set around for all those years. I plan on not racing it but car shows and driving it around. I hope it is done in one more year because I would like to start driving it. I still have to figure out how two run the two outlets to the carb hat. and if I should run a blow off valve in the outlet tubes also is it ok if I keep the hose size 2.75 to the hat or should it get larger. I was going to go with one paxton but I think two look cool. I'm not going to race it so my main thing is to get it to run go with the two blowers. And the plan is to put the idler on the top of the belt in the center and push down on the belt to tight it I hope it works I was thinking of finding a 8 rib crank pulley and going with 8 rib set up. But Im not going to be racing at the track so I hope the 6 rib works ok on the street.

Thanks

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