[F-BIRD'88]

There is a dyno test of a similar blown 327 with a 142 bloer and 5psi boost, on a chassis dyno.
it made 312 hp.. it made 234HP on the chassis dyno with no blower.

The Crane F278-2 cam is a nice mechanical street blower cam.
If you want a hyd cam use Crane HMV278-2. another proven great street blower cam.
The boost curve and the resulting engine's whole power curve will be a lot better with these cams.

The headers and exhaust system fix will make a huge difference.

As stated a 650 carb will limit the power the blower can create. it limits the air flow.
A 750 to 850 will make more power, especialy at higher blower drive ratios.
A blower takes big gulps of air and needs a big cfm carb or power is restricted.

A 650Double pumper can be easily upgtraded to a 750+cfm HP carb using the Proform HP carb body kit.
Very effective and you pick up the ability fine tune the idle and hi speed air bleeds. Great for blower motors tuning.
The carb power valve needs to be boost referenced when using high boost. Or the power valve will not function properly and engine damage can result. its easy to do on the proform body.

[F-BIRD'88]

Chassis dyno number are always very humbling..But the drag strip MPH VS car weight(w/driver)
never lies.

Again the high 9:1 compression ratio will require high octane gas for higher boost settings.

When you get the exhaut/cam/carb fixed up get some 110+ octane fuel and up the boost and timing and you will see just how much power that 177 blower can make.
Your "ported" heads may need more work. but the exhaust is a real cork and the comp 292 magnum cam is not helping.

A well designed electronic water-methanol injection system will allow high boost on good pump gas.
allows more boost and timing under boost by supressing detonation.

But always do your initial testing using 110+ high octane gas.

Do you have a boost-- timing retard box?

[1971chev]

Yes I have a msd 6 btm

[F-BIRD'88]

Originally Posted by 1971chev

Yes I have a msd 6 btm

Aussume You are off to a good start and will get there.

Does this 327 have a flat top piston in it.? and a true 64cc head?

piston deck clearance @TDC.? (block was decked) The real cr may be actually higher than 9:1
meaning you really got to watch the boost and timing on pump gas.
It's going to be limited by the fuel in the tank.

A low 7.5:1 compression ratio allows high boost and a lot more power on pump gas with minimal spark retard.

[1971chev]

flat top with 4 valve relief pistons

[F-BIRD'88]

A -26cc to -30cc dished piston would really allows you to hit it with some boost on pump gas.
7.5:1 10 to 12psi
Changing the cylinder head to a modern aluminum hi flow with a larger combustion chamber is a more practical solution.
76cc to 80cc optimum

You could sell your nice camel backs to recover much of the cost.
You will kill two birds with one stone.
Drops the compression ratio to allow more boost
Improves port flow and combustion chamber design for more power.

[F-BIRD'88]

Question: What car is this supercharged 327 in?

[cdminter59]

Originally Posted by Hogg

You realize it has a supercharger on top, right?

F bird has some good advice.

peace
Hog

I read he had a Weiand 177 blower on it. He thought the dyno numbers were low. I gave him the reasons why. Restrictive heads and exhaust, the cam too big (not for use with a blower engine). I didn't even mention the small 650 carburetor. It is just a case of incorrect parts for the type of engine rebuild. I see F-Bird'88 recommends changing to headers, a Crane cam (for a blower engine), larger aluminum heads to reduce c.r., and a 750 carburetor.

[1971chev]

The motor is in a 71 c10

[F-BIRD'88]

Originally Posted by 1971chev

The motor is in a 71 c10

Cool ... Could you tell me more about the exhaust system?

Corvette Ram Horns: The good ones that make power have a 2.5" outlet and large internal passages. 63 to 67 corvette. There are many others that look like Ram Horns but are not the same. Late 70s smog era corvette stink, anything from a truck or old impala 283 really stink. They have a much smaller outlet than 2 1/2"
(2" typical)

. Look similar to the real deal but not a high performance 63-67 Corvette Ram Horn exhaust manifold at all.
What do you have on your truck for manifolds and exhaust system?
The OEM SBC truck center dump exhaust manifolds are similar looking and often confused.
The exhaust system is critical to a blower motor.
Tell me more about the cylinder heads define "Ported"
Fully competition ported and flow tested or a little pocket port job (minor grinding under the valve job in the bowl)
Blowers need head flow too.

Pretty much any 1-5/8" long tube header is going tomake a lot more power than even the best of the ram horns
( average gain is 12% to 15%. May be higher even depending on the actual manifolds and exhaust system.

12% to 15% is typical
A 1-3/4" long tube header is good too. A blower motor needs to breath deep and get rid of the increased exhaust volume.
Much like a big block.

Tell me about the transmission/converter and tires and the dyno test conditions.
Blowers like to breath in cool air. Under hood air can be quite hot and reduces supercharged power.
Cold air is better. Cold air picked up from the front of the truck (Ram AIR) is even better and typically allows more blower boost and timing (more power) www.ramairbox.com or a good sealed hood scoop.

[1971chev]

I believe they are the smaller ram horns cause they dump out the back, Im pretty sure the vette ones are straight down. The rst of the exhaust is 2 1/2 inch all the way out the back with pypes violator mufflers.

[F-BIRD'88]

Originally Posted by 1971chev

I believe they are the smaller ram horns cause they dump out the back, Im pretty sure the vette ones are straight down. The rst of the exhaust is 2 1/2 inch all the way out the back with pypes violator mufflers.

Then switching to a good tube header is going to make a big difference.
SOme tube headers are small inside. only 1.5" internal diameter.
You want to avoid these small headers.
1-5/8" 1-3/4" is best.

Some mufflers don;t flow air very well and also restrict a supercharged motor.
Its all about air flow. No experience with Pypes mufflers thu.
The cam you have tends to delay boost at low/mid rpm.
Too much overlap. BY the time it makes boost at higher rpms the exhaust is restricting power.

A Crane HMV278-2 #113801 camshaft works really good with that blower.
best with a 1.6intake and 1.5 exhaust rocker arm but fine with just 1.5's.
More power, sooner. The valve events and overlap are a lot more blower friendly, especialy on a 327 with the blower and modest boost.
With a 1.6 intake rocker the valve lift is .498" intake and .494" exhaust. (1.5:1ex rocker is fine)
Very near hyd roller cam performance at a flat tappet cam price and very sweet on a 327 w a blower.
The HMV-278-2 cam and lifter set part number is 113802
if you need technical assistance or just want to gab (get a recommendation, etc) you can call or email Crane Cams.
They are there to help you. It's worth the call.
www.cranecams.com

[1971chev]

So with a cam swap and long tubes what kind of hp could I see.

[vinniekq2]

Post your dyno sheet and lets look and see what needs the most work

[1971chev]

I didn't take the print out, but when I get back to the shop I will get it