help with hypereutectic pistons & a procharger

[jubin]

I need some help I am building a 400 for my 72 roadrunner and I am using kb240-40 hypereutectic pistons that I have already fitted to the stock rods but here is my problem I just picked up a procharger that I would really like to put on this set up . Can it be done and would it last?

 

[jubin]

paid 400.00 for the blower and it is in perfect condition

 

[moparpoor]

Yes you can,you will just have to limit the boost.What are the specs on the blower and the rest of the motor.

 

[lewtot184]

top ring gap will need to be increased. i'd probably use a cam with 112-114 lobe separation and limit boost to 6-8lbs. look on the KB website for additional info.

 

[Budnicks]

Yes you can make it work, but, It really depends on, What compression ratio ?, What are your current bore clearances ?, With supercharged engines, many/most times they need a little more clearances for the extra heat that a supercharger adds to the equation... What camshaft ?, Is it designed for boost ?, What are the piston down in the block ?, Are they at zero deck or what measurement down in the cylinder hole ?, What is the quench area ?, Have the heads &/or block been shaved/milled ?, What size are the combustion chambers ?, What size are the valves ?, What style of head gaskets & thicknesses ?, What ring sizes, materials, gaps & locations ?, What diameter blower drive pulleys are you going to use ?, What boost level ?... Forged pistons are far better for engines with high boost, you probably can get away with running the KB Hypertech. style pistons, you will probably need to limit the boost level for sure, to be on the safe side...

 

[HEMI-ITIS]

Yes you can make it work, but, It really depends on, What compression ratio ?, What are your current bore clearances ?, With supercharged engines, many/most times they need a little more clearances for the extra heat that a supercharger adds to the equation... What camshaft ?, Is it designed for boost ?, What are the piston down in the block ?, Are they at zero deck or what measurement down in the cylinder hole ?, What is the quench area ?, Have the heads &/or block been shaved/milled ?, What size are the combustion chambers ?, What size are the valves ?, What style of head gaskets & thicknesses ?, What ring sizes, materials, gaps & locations ?, What diameter blower drive pulleys are you going to use ?, What boost level ?... Forged pistons are far better for engines with high boost, you probably can get away with running the KB Hypertech. style pistons, you will probably need to limit the boost level for sure, to be on the safe side...

What he said:iamwithstupid:

 

[jubin]

it is a early 1972 block 40 over
I have a set of 516 casting heads with the bigger valves
and I am using a purple shaft cam I have a set of flatline multilayer
head gaskets and the rings that I am using are the ones that came
with the keith black pistons as I said this was going to be a simple pump
gas motor but I ran into the blower????

 

[Deleted member 214]

There are a lot of "purple shaft" cams - every single Mopar Performance cam from the stock split duration "Road Runner" cam through the .484 and .509 cams and beyond. Which one are you using?

 

[jubin]

.509 sorry

 

[67 coronet]

the hole key to this is comp ratio to boost amount.if it is too much you just make a bomb!ring end gap is a big deal as well,too little with the forced induction and your rings will cut the top off your pistons when super heated.if you are assembling a fresh motor ask your machineist if they know the spec answers.

 

[HEMI-ITIS]

I don't think those pistons are boost or nitrous friendly.Yea,they can handle just a little.But for how long and what you think is "just a little".
I would change the pistons while you have it apart.I went with Diamond this go round.Had CP last round.If you want to step on it with a power adder,new pistons:violent-smiley-100:

Here's some detonation damage.

 

[jubin]

I call kb and they told me .008 per inch of bore 4.380 that makes the top ring gap of .035
This sounds like a lot to me but could it be that the top ring on this piston sits so high up
Man and I just got these pistons and they are on the rods I can return them. looks like I am stuck like chuck what a dilemma to have. LOL LOL

 

[HEMI-ITIS]

I know it suks that you already bought pistons.If they won't exchange them,you'll be able to sell them.Once you have BOOST,you'll wonder why it didn't happen SOONER!!!:toothy10:

 

[jubin]

You are right HEMI-ITIS the foot is going to the floor more sooner than later I wish I did not find that blower but it is here so I have to do something with it. I cannot use it for a paper clip it is to big
Going to see how much new piston cost ???

 

[jubin]

Yes I now boost is the sh*& I have a 72 Buick gs with a sbc and twin 6765 precision and I love it
I have JE pistons in that motor

 

[HEMI-ITIS]

Have I seen that buick at Home Depot in Davies on a Friday night??

 

[jubin]

Not mine my hot rod has not seen the road like in 5 months
and it leaves at my house in islamorada florida

 

[robinsonwr]

Jubin,
I called KB and was told they have tested their hyper pistons up to a 300 shot of nitrous. The pistons are pretty rugid parts that will with stand alot more than they say it can handle. Manufacturers always set tollerance levels much lower than failure limits. Do not get me wrong if you are building an all out racing motor I would use forged, just saying.

 

[HEMI-ITIS]

I have not been in Fla for over 2 years.My parents were in Coconut Creek for years.When I used to see them for vacations,I scoped out all the hot rod hang-outs in that area:blob1:

 

[jubin]

It fun down here at the bottom of the USA