Cut off line for Cast and stock internals

[74Dusted]

What's the general census on cast internals & some stock parts (crank for example) at "x" boost before the need to upgrade to better internals?

The creature in question is a '69 340 Short Block with 60 over Keith Black Hyperereutic pistons, Stock forged crank, stock rods. (rotating assembly hasn't been balanced yet) Never assembled, getting the engine in trade for doing work to a friend's car.

Figured the Block & Crank would be a good starting platform for a mild Supercharged 340 to stick in one of my A-bodies. Don't know about the pistons, compression ratio is probably too high on them to use for the build. But is there a certain point where cast pistons are ok to use, or is it one of those deals where I should just get Forged pistons anyway?

Figured I'd keep the boost somewhat low and reasonable, Street Car. No need to go hogwild on exotic parts or an extremely radical engine

 

[Mad Dart]

There is good information here, it will take more than most give them credit for.........

http://www.forabodiesonly.com/mopar/showthread.php?t=165579

 

[Prine]

Depending on your Compression Ratio..8:1 is ideal, 9:1 is workable, anything over 9.5:1, I do not recommend to FI-Charge for street use...(and I know what a stock 69 340 has)....the cut off is when parts break.

There are too many variables in the parts of YOUR System, that YOU will choose based on cost/durability.

The Fuel System is highly important on Forced Induction Engines....inadequate fuel VOLUME, and FLOW will lead to a grenaded engine in a HURRY.

Power wise cast pistons, and cast crankshafts will withstand over 600hp at the crank...and about the same torque.

Detonation (caused by HIGH INTAKE AIR TEMPATURES, and too low octane fuel) is what kills most engines.

 

[Bill Dedman]

What's the general census on cast internals & some stock parts (crank for example) at "x" boost before the need to upgrade to better internals?

The creature in question is a '69 340 Short Block with 60 over Keith Black Hyperereutic pistons, Stock forged crank, stock rods. (rotating assembly hasn't been balanced yet) Never assembled, getting the engine in trade for doing work to a friend's car.

Figured the Block & Crank would be a good starting platform for a mild Supercharged 340 to stick in one of my A-bodies. Don't know about the pistons, compression ratio is probably too high on them to use for the build. But is there a certain point where cast pistons are ok to use, or is it one of those deals where I should just get Forged pistons anyway?

Figured I'd keep the boost somewhat low and reasonable, Street Car. No need to go hogwild on exotic parts or an extremely radical engine

I have an engine similar to what you suggest.
Mine is a 1998 Durango 360 Magnum with cast (hyperuetectic) OEM pistons, stock rods, a cast crank, 9:1 compression (measured with a burette) and a mild cam from Hughesengines. It has a Vortech centrifugal supercharger running at 10 pounds of boost and makes 445 rear wheel horsepower, according to a local dyno shop test.

To control potential detonation, I have a Snowperformance Boost Cooler water/methanol injector set to start spraying at 3 pounds of boost, and an MSD BoostMaster cockpit-controlled retard unit.

I have had no head gasket, or other boost-related problems with this engine so far.

The engine is in a '72 Valiant 4-door sedan.

Installing the blower reduced the car's e.t. from 13.35 to mid-11s, and the MPH increased from 102 to about 118, Made a whole new car out of it, but you have to be careful; detonation will kill a combination like this in a heartbeat... Be careful with mixture and spark advance, and you'll be fine.

Good luck!!!

Here is the Chassis-Dyno sheet and a picture of the car it's in...

 

[74Dusted]

Thanks, I appreciate the info and dyno sheet.

I'm kind of familiar with Water/Methanol Injection, since I was looking into it (briefly) for my '84 Turbo Diesel D50 pickup. But I'm curious, are there any negatives to running it on a Street driven Gas Engine? Abnormal wear, Potential other issues?

Of course when I say street driven... The 340 in question might see 10,000 miles in 30 years, if that. As an Example, I use my '74 Duster as a Daily Driver in the Summer (switching to my truck when it rains...that car is a death wish in the rain) And I've been driving it since 2007... In 2007 it had 103,103 miles on it. When I parked it for the Winter about a month ago, it had 103,890 miles on it.

4 Years of driving it and it has yet to reach a thousand miles of use.

 

[Bill Dedman]

Thanks, I appreciate the info and dyno sheet.

I'm kind of familiar with Water/Methanol Injection, since I was looking into it (briefly) for my '84 Turbo Diesel D50 pickup. But I'm curious, are there any negatives to running it on a Street driven Gas Engine? Abnormal wear, Potential other issues?

Of course when I say street driven... The 340 in question might see 10,000 miles in 30 years, if that. As an Example, I use my '74 Duster as a Daily Driver in the Summer (switching to my truck when it rains...that car is a death wish in the rain) And I've been driving it since 2007... In 2007 it had 103,103 miles on it. When I parked it for the Winter about a month ago, it had 103,890 miles on it.

4 Years of driving it and it has yet to reach a thousand miles of use.

If there are any negatives, I am unaware of them.

The liquid in the spray gets turned into a gas immediately in the combustion chamber, so there are no rust issues.

The advantages afforded by such a system would seem to far outweigh any negatives that might pop up. The hard part, if you did a lot of street driving and were using boost a lot of the time, would be to moniter the reservoir and not run out of fluid...

Other than that, I don't see a problem.

But, I don't have a lot of experience with this; I drive my blown car very little on the street.