Carb Supercharger
 

Does anyone run a supercharger on a small block with a carb? What is the driveability of such a set up? I'm sure the power is awesome. Where did you purchase your charger kit? Looks cool.

thanks Dennis

Try looking at either Paxton or Vortech's websites. i saw cars, but not cobras, with carb's and superchargers. I think it would be pretty scary to drive one if you weren't used to 700 hp. As for driveability, the more boost you go for, the more you'll pay at the pump.

You can't run very much boost on a through-the-carb setup.

Dennis I'm going that route and I'm gonna be putting it in a BDR. email me and I can send you info.



Sid

:)

Not sure of the cleareance in the BDR, But a number of FFRs with the 302 are running the Holley Roots type blower. Both the 144 and 174.

Mike

There is a clearance problem with Paxton and you need to make custom brackets. The Vic Jr intake will not work. But the Performer should be fine.

sid

been there , done that...SEE PICS IN MY PHOTO GALLERY,

as i added a 60s era ball drive paxton blower upgraded to vr-4 specs to my 351 windsor in a spf with 780 custom pro systems built holley and dual plane manifold. the fit is tight, lots of custom bracketry etc needed to install. getting the plumbing for air intake over the valve covers was tough and to make it fit it had to be compromised, ie, tubing somewhat squashed.

car ran like a banshee, sounded like a f-16 fighter , threw you to the rear bulkhead as the blower spooled up and looked great. when the hood went up no one cared that it was not a fe or bb.

however, i had been misinformed about the metal content of my pistons and compression ratio . i took someones' word without checking it myself . i had bought a used car and there were engine misrepresentations made i discovered during the post blower autopsy. hence my blower at 9 pounds of boost and 3,000 miles later blew the tops off 3 of my pistons and the edges off of 3 others, as well as some valve damage as those metal pieces were ingested and eventually became schrapnel in my side pipe packing, with some getting blown out the pipes. oh, what a mess....oh yes, i had been cautioned by many, including the installer, that this was a risky install, but i proceeded nonetheless. others were more right than i was.

so, if ya add a blower, make sure your lower end is built for one, your pistons are of the right metal content and your compression ratio is low enough to handle it and then be cautious on the boost of the blower...or as the blower suggests, it will blow.,as in blow the motor as mine did. the blower however remained intact and is good as new.

i sold the old engine, bought a new 392 stroker ford racing engine and put the paxton and attachments in boxes as garage art as a reminder of silly money spent and lesson learned. no blower for me on the new engine.

while the blower is unique , it is many times wasted dollars at the expense of engine longevity vs a new bigger motor from the start...or different heads and other power addder aftermarket add ons. there are other cheaper ways to get same or similar horsepower. others have been luckier than me and have not had catastrophic failures like i did.

darn, i sure miss that blower on the car...now i cant decide whether to sell it or put it on my modified k-code engine in my 65 stang...til i get off my duff and decide, it remains garage art and a conversation topic....oh, it was so pretty !

good luck to you adverturesome blower inclined installers...next time around i will ensure that the engine getting the blower is specifically built for intended blower usage...bill, motown, spf 156

My motor is from EF with dished forged pistons and rods. Comp will be little under 9:0. INTERNALS ARE VERY IMPORTANT! Did a lot of research before desiding to go this route...For the same money I probably could have had a 418 built. But I wanted cool look under the hood. And the scream of a supercharger is addictive just like BOOOST!!! oh sweet boost....LOL!

sid

Sorry digging this up, I am running a chevy 350 with a old B&M 144 with a 830cfm carb. It's not streetable due to the gas milage but everything else is holding up fine after 5000 miles of road racing abuse. Of course the motor was way way over built for the amount of boost that is running through the motor ~5 pounds right now. I have the build sheet somewhere on my computer but to say the least the motor runs about 7:1 and does not ping on 91. It loves 106 though. I am actually putting the 3 pound pulley and some ~3.3 gears in it this weekend so that it gets better the 7 mpg.

Things to look out for, make sure that you don't have any flow restrictions, your supercharger will creep up the recorded boost as it builds at higher rpm's. So now you have super hot compressed gasses which robs you of a lot of the power that you were making with the boost, and two you will have a heck of a time getting the idle set right, as some superchargers cause a vacuum condition on an idling motor the idle parts in your carb flip out.

There are ways around this but they are application specific.

A supercharcharged engine can be very streetable.

You'll need forged low compression pistons and the best piston rings you can get.

A cast crank and stock rods should be fine for a street engine.

You need a cam with lobe center in the 112° range so the blower won't blow out the charge through the exhaust valve due to cam overlap. Lift and duration should be a bit more than stock.

If you intend to use the stock heads open up the exhaust ports as much as any possible because they are so restrictive.
Use the D8OE heads with 69cc combustion chambers as found in '79 Mustangs, the big chamber volume will help to achieve a compression ratio low enough.

For a blow through setup a single plane intake is recommended to avoid fuel distribution problems.

Check this link from Mustang Magazine January 1989 edition on carbed supercharging:
>Super Charging 302<

Furthermore I recommend the book "A do it yourself guide to street supercharging" by Pat Ganahl.


Simon

Personally, I like keeping things simple, building an engine once, and enjoy driving it rather than fixing it. Not enough power? Put in a bigger engine.

That being said, there is a guy at CACC running a relatively stock EFI 302 powered FFR with a Vortec S trim hair drier. With relatively conservative boost, 4 psi or so, he can blow the doors off most 460's, gets 22 MPG over the road, and drives it to work.

His name is Wade Chamberlain, and he hangs out at capitalareacobraclub.com. He's an engineer (mechanical) and got all the details right. Look him up.

Inside joke (DoD). Mechanical engineers build weapons systems, civil engineers build targets, and environmental engineers (like me) clean up the mess afterward. Job security, ya know.

There's another guy at CACC running a Paxton s-charger in a Windsor stroked to 427CI, by the nickname of Schrapnel (no, not kidding).

I agree with Jack above that Wade is a superb resource. He is the top HP dog at CACC with 444 chassis-dynoed RWHP (in a blown 302), a feat he essentially duplicated at DVSFIV.

Wade has a great set up! He does have an advantage of the EFI. A carb set up will need a good tuner and some extra dyno time to set it up right.

sid

I have run a blow-thru set-up on both a 289 and 351W. I use a used procharger I bought for 1200 dollars, seems bullet proof.
Comp cams makes several great blower cams, mine is a 512/520 lift. I ran a 9 to1 compression bone stock 289 with 7 lbs of boost and got 300HP & 340 TQ at the rear wheels. The 351W I had built with forged pistons & ARP bolts and run at 10 lbs of boost.
It Dynoed at 330 HP & 380 TQ at the rear wheels needing Carb & Timing adjustments. After Dyno Tuning I should gain 40 or 50 more on both the HP & TQ. If your interested I still have the custom built 625 CFM Holley Blow thru Carb that I will give you a good deal on ( I had a 750 CFM built for the 351W). Jay

That does not seem like you are getting a lot of HP at 10 lbs of boost. My 351W dynoed 351rwhp. Are you sure about those numbers?

I was going to say the same thing. Are you sure that you are not seeing boost creep on the gauge. It also might be in your interest to install a temp sensor inside the intake housing after the blower.

Also since this is a blow through carb design you might need to get a larger carb. The ventri's might be to small for the amount of boost that you are running, or you have a head restriction. You should see a lot higher numbers then that. On my SB 350 I am approching ~550 on 5-6 pounds of boost at the crank, mind you I run a different style of blower.

Thanks for the info. The Dyno run showed that my advance is going from 12 deg. to 40 deg total ( way too much) and my secondaries are flooding the engine when the kick on. After a distributor recurve, carb work, and 2 hours of dyno tuning I should see much better numbers. Jay

Jay, if you are using the stock 351W heads this might be the problem. Both the valves and especially the exhaust ports are too small for a supercharged engine of this size.

This causes boost pressure to build up in the intake manifold, the air/fuel mixture gets heated due to the restricion what shows as more boost on the gauge, but actually there's very little boost entering the cylinders.

Enlarging the exhaust ports as much as possible will help. This is a D8OE head I prepared for supercharging:


http://img17.exs.cx/img17/8189/ports.jpg


As long as you're up to it you might as well polish the combustion chambers, this will reduce the compression ratio (meaning you can run higher boost) and sharp edges in the chambers will be removed to avoid hot spots that will pre-ignite the mixture:


http://img17.exs.cx/img17/1349/chambers.jpg


Port matching the heads to the intake also won't hurt.


I did all this work in my garage with hand tools. It isn't complicated, it just takes some patience.


With bigger valves stock heads prepared this way should be capable of ~500hp.


Simon

Dennis,
There is a master mechanic on Long Island who has been doing engine installs on Cobras for the past 5 years and had been working in the Ford industry for 30+. Every Cobra that he works on (SPF, ERA, UNIQUE, CLASSIC, E-M etc....) he treats as though it was his own. He CARES. He has been getting calls from all over the country on Paxton Supercharger installations on carbed engines. He has designed all new brackets and moved the alternator over to the drivers side. He even has Paxton sales people calling him for info. The results on the Dyno of a 351 Windsor (stock SVO) with a Paxton are really unbelievable. His name is Nick Losurdo and can be reached at Classic Concepts 631-643-4611.

John