looking for blower pistons for 300

dj65falcon

Well-known member
Hey guys. I have a 300 with 240 rods. Puting on a paxton supercharger. Need to know what part number for a blower pistons. Or where to go to get custom piston. Thank for your help
 
As you already know the Paxton Novi GSS supercharger is a ball drive unit and 7 lbs of boost is a good limit for it.
Even though that is low boost, if you want a good safety margin I still would recommend a forged 2618 alloy piston.

We use Diamond pistons for racing applications.
The least expensive 2618 alloy pistons is Racetec.
In any case it will be a custom piston.

The pistons can be made with an accumulator groove between the top and second piston ring to prevent ring flutter. That is usually standard for Racetec.
If so then use BWE piston rings with a ZG second ring. There will be a lot less blowby under boost.
I picked up 2 inches of crankcase vacuum with a ZG second ring in our blown alky engine.
Bruce Walker at BWE will help you with ring selection.

This is a forged 4032 alloy Autotec piston for the 1965-1968 .912" pin 240 rod on a 300 crank with the accumulator groove.
It has a 10cc dish for a 9.75 compression ratio in a naturally aspirated 300 six
https://dl.dropboxusercontent.com/u/393 ... C01572.JPG

You will need to know the piston ring dimensions before you can order pistons.

I noticed you are using a large mechanical lifter cam.
Is this engine for street/strip?
 
Thanks for the tip. Yes it is a street and strip car. But i took to the track last sunday and blew up the motor. Put a hole in#2 piston and it was missing a top ring land on#2,#5,#6. The piston were Keith Black Hypertech pistons and they suck luckily I have a spare motor in the wings so I thought I put blower pistons on this here's a pic of what they look like after I took them apart today20170815_183733.jpg
 
Thanks for posting a picture of the broken piston. Will make a good reference for hypereutectic piston breakage.
The engine was definitely running under detonation.
Hypers are very brittle and will not tolerate detonation or shock loads.

I recommend dropping the compression ratio down to 9:1
You can also pick up more low to mid range power with a shorter duration camshaft.

Why the choice of a 256* mechanical cam?
 
I got that camshaft because of my 3500 stall. I think I might have found out my destination problem. I have a Holley HP 125 that flows 110 and 7 PSI I don't think that was enough for my supercharger. I'm think about upgrading to the Holley HP 150 it flows at 140. When the car was at top end my fuel pressure reading at 4 PSI. I hope I am on the right track if not please give me some suggestions thank you
 
The fuel pressure needs to be boost regulated so that 1 psi of fuel pressure is added for every 1 psi of boost.
With a base fuel pressure of 7 psi there needs to be 14 psi of fuel pressure at 7 psi of boost.
 
Ok now my question is. I do have a fuel regulater with boost referance. The line goes from the boost line to the carb.was this the right way? Or should it be to manifold vacuum?20170806_130043.jpg
 
The fuel regulator boost reference line goes directly to the intake manifold.
The fuel pump must also be able to supply at least 15 psi of pressure.
 
No my Boost line was hooked up to the carb hat and my fuel pump is regulated at 7 PSI you cant adjust it so there was my problem
 
I stand corrected, carb hat connection is correct. I'm used to thinking EFI.
Fuel pump pressure is a problem.

There is also a concern with the fuel pump pressure dropping that you observed.
When you finish the next setup, test the fuel system before running the engine.
We used to run a fuel line from the connection that goes to the carb into a bucket with a jet at the end of the hose the same size as the carb's float needle jet.
Then we used our leak down tester to regulate the pressure to the boost reference on the fuel regulator to see if the pressure tracks.
 
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