Anyone running a Paxton on a 340?

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swinger340

swinger340

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Wondering if there any issues with the paxton and what kind of real world gains they can provide.
 
Anyone sell a turbo kit for a small block A body? If so where should I start looking?
 
will be running one once i get the engine built
 

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That's a cool setup! Very period-correct and should make that 340 flat-out fly. There's a company that does these Paxtons up to add 3 to 4 extra lbs of boost with a more modern impeller.

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I found a company that sells a complete Paxton set up for a small block A body for $2500. It produces 8 lbs. of boost @ 6000 rpm. Not sure what kind of gains would be expected. Is 8 lbs of boost to much for 9.8:1 comp motor? Wonder if it would run fine on 93? I figured maybe someone has been there and can share some helpful tips so my investment wont be a total waste.
 
8 LBS at 9.8 to 1 is instant death of the engine unless you are running alcohol or race gas. Or you have some real good meth injection going on. 8.5 to 1 with about 6 lbs of boost is about the limit for 93 octane.

Jack
 
I'm not a forced induction guy, but a quality ignition with some form of boost referenced timing retard will be your friend.
 
Coyote Jack said:
8 LBS at 9.8 to 1 is instant death of the engine unless you are running alcohol or race gas. Or you have some real good meth injection going on. 8.5 to 1 with about 6 lbs of boost is about the limit for 93 octane.

Jack
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That's not even close. I have 10lbs on my 9.5 to 1 mustang on 91 octane all day long. It's all in the tune. Hell I'd boost my 10.5 408 if I had the means to afford it. But I'm way over budget as it is.

http://www.paxtonauto.com/product.php?id=127 at 8lbs you may get around a 50% increase in output.
 
Off topic some but I run my Sti 23 psi on 93 octane at 8.5 compression. I have zero detonation or knock. As stated above all in the tune
 
swinger340 said:
Wondering if there any issues with the paxton and what kind of real world gains they can provide.
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I have a Vortech centrifugal supercharger (V-1 / S-Trim) on my 360 and although I don't run it on pump gas (I use Av Gas; LL-100, which is about 110 octane I am told, using the pump gas arithmetic to figure octane,) I have only good things to say about the move to forced induction.

I have pulleys that give me 10 pounds of boost at 6,00 rpm.

When I supercharged it, I also added some TTI headers to replace the early 340 exhaust manifolds I had been running, and I took the M-P 360-degree intake manifold (water heated!) off and replaced it with a Chinese copy oFan Edelbrock AIR GAP.

No other changes. No intercooler, but I did install a Snowperformance Boost Cooler alcohol spray unit to try to stave off detonation.

The car us a 1972 Valiant 4-door and weighs 3,430 with no driver aboard.

After the supercharger installation I ran it on a chassis dyno again, and my rear wheel HP increased from 260 to 445. My quarter-mile e.t.'s went from 13.35 to mid elevens. MPH went from 102 to 118.

Here are some pix...,

I think it's a viable alternative to turbocharging.

My other car is turbocharged, BTW.

I made my own "kit." It was time-consuming, but fun!

The thing feeels like a 440.... stroked. I changed tires to some 9" Hoosiers and went from a 3:55 to a 4.10, recently. Should run low 11's @ about the same MPH, now...

Talk's cheap; we'll see, when the good weather gets here.


That price of $2,500.00 sounds like a really good deal to me!

I spent a LOT more than that, putting mine together.

Good luck!!!!:D
 

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If compression may be an issue I could always drop my W2s with thicker head gaskets on the girl to drop it down to the 9.2:1 area. Id just as soon keep my edelbrock heads though.
 
I know my brother installed a Vortec supercharger on his 9.5:1 5.0 mustang w iron GT 40 heads and he loves it. Although he has major traction issues.
 
swinger340 said:
If compression may be an issue I could always drop my W2s with thicker head gaskets on the girl to drop it down to the 9.2:1 area. Id just as soon keep my edelbrock heads though.
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Those aluminum heads can dissipate heat better and faster than iron though, and the thicker head gasket may ruin the quench between head/piston I'm thinking.

Bill Dedman said:
I have pulleys that give me 10 pounds of boost at 6,00 rpm.
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Have you had any carb issues running your pressurized carb, Bill? (leakage etc.) I believe I heard Holley has specially made carbs for these applications. I used to hear stories about carb floats getting crushed from the boost.
 
A couple of good points are made in this thread.

Run W/M injection as Bill Dedman does to ward off detonation. And like Bill, run some gears in the rear, 3.55 or numerically higher. Less strain and load on engine, equals less chance for detonation.

X2 on using aluminum heads as Cudavert suggested. A tight quench will help ward off detonation.

Run a 6BTM (or equivalent) ignition box, use non projected tip spark plugs, and try to keep the engine as cool as possible.


Swinger340, what cam are you running?
 
MiradaMegaCab said:
A couple of good points are made in this thread.

Run W/M injection as Bill Dedman does to ward off detonation. And like Bill, run some gears in the rear, 3.55 or numerically higher. Less strain and load on engine, equals less chance for detonation.

X2 on using aluminum heads as Cudavert suggested. A tight quench will help ward off detonation.

Run a 6BTM (or equivalent) ignition box, use non projected tip spark plugs, and try to keep the engine as cool as possible.


Swinger340, what cam are you running?
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Comp XE282S .520 .540 solid flat tappit. Im pretty sure my bottom end is strong enough. Did oiling mods. SRP forged pistons, Scat H beams, ARP main studs w/ a girdle. Block was originally prepped for a stroker build, but then I got a deal on these pistons and rods so I decided to use what I already own. Weak point is the factory forged crank that has been turned .010/.010
 
cudavert said:
Hope that cam isn't too crazy on the overlap......they say your boost will "go out the exhaust pipe" if it is.
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Not sure on the overlap but duration @ .050 is .244/.252 If need be, a cam swap is easy enough.
 
Do you know the cam manufacturer and part #? I think a narrow LSA is not the hot setup on these, like a 108 or 110.
 
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