Piston/Ring combo's for 10:1 383

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Reddartowner

Reddartowner

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Hi...

Working on setting up a build for a 383 to go in my son's Dart. The basic setup will be like this:

9.5 to 10:1 compression
Comp Cams XE262H (building this motor for torque, not all-out HP)
Stock Crank
Reworked stock rods
Approx. 75cc heads to get compression with flat top pistons.

What pistons/rings would you recommend for this sort of build.? So far I've looked at Speed Pro and Diamond pistons. Any particular brand of rings that stand out..?? Any other pistons to consider.?

Thanks....
 
While I'm not a big fan of hypereutectics, what opinions are there on the KB162's with 75cc heads or KB400's with 84cc heads ?? I've begun to see that my piston choices are rather limited.
 
I feel about the same way when it comes to hyper pistons...if you can swing the extra money, Diamond makes great slugs. The only other way to select light 383 [forged] pistons I know of would be to run a 440 rod...it's longer, sets the pin up higher; therefore, less skirt, less height, less weight. It also raises the rod ratio a little bit...not that a 383 needs to increase rod ratio, but it would.

I don't know of anyone running the KB hypers, but I have seen pictures of them cracking/breaking at the first ring land if they're run too hot or with too much advance. I'm sure that's probably the exception not the rule, but it still lunched that cylinder and one head. I would have to believe that if you abide by KB's recommendations they'd probably be OK to use as long as you weren't spraying more than 100 shot or more than about 8lbs of boost and appropriate tuning.
 
Iron or aluminum heads? You may already have considered all this, so forgive me if this is just preaching to the choir. With that mild of cam you may run into detonation on pump gas with 10:1 on iron heads. Lot of factors can come into play including proper quench and true static compression. Damn this crap gas! I have not yet cc'd my heads nor have the short block assembled to measure piston depth, but I figure my compression should be in the same range as you are looking. To keep the dynamic compression in a safe range for pump gas I jumped from the 268 duration cam I wanted to 276. Just something to look into. Here are dynamic compression calculators online, and from my own research it appears 8:1 dynamic is optimum for street use.

The Hypers get a bad name from people not filing the top ring properly. The top ring will expand and bind if not gapped properly and breaking the top ring land. When properly gapped a healthy motor will run strong for a long time with Hypers. They fit tighter in the bore so Little if any knock.
 
MTmopars said:
Iron or aluminum heads? You may already have considered all this, so forgive me if this is just preaching to the choir. With that mild of cam you may run into detonation on pump gas with 10:1 on iron heads. Lot of factors can come into play including proper quench and true static compression. Damn this crap gas! I have not yet cc'd my heads nor have the short block assembled to measure piston depth, but I figure my compression should be in the same range as you are looking. To keep the dynamic compression in a safe range for pump gas I jumped from the 268 duration cam I wanted to 276. Just something to look into. Here are dynamic compression calculators online, and from my own research it appears 8:1 dynamic is optimum for street use.

The Hypers get a bad name from people not filing the top ring properly. The top ring will expand and bind if not gapped properly and breaking the top ring land. When properly gapped a healthy motor will run strong for a long time with Hypers. They fit tighter in the bore so Little if any knock.
Click to expand...

We'll be running aluminum heads, probably Edelbrock E-streets since they come with 75cc chambers and will allow us to get the compression we want (9.5 - 10). In the range this motor will be run, huge flow numbers aren't necessary. And I think we'll probably go with the Diamond forgings. They are considerably lighter than the Speed Pro's (150 grams per piston lighter....). That takes a LOT of stress off the recip. assembly. I also plan to have the skirts coated by Swain Tech to help prevent any scuffing and maybe free up a couple of HP...

Just checked the planned combo with a dynamic compression ratio calculator and it comes out to 8.38:1. So based on your experience I'm into aluminum head territory, which is what I figured I would be. Here's a question..... think this motor will run on pump premium OK with aluminum heads ??
 
The rule of thumb is the aluminum heads generally allow you to run an extra point of compression.
 
I am building a 383 with the KB400 pistons with stock rods. I am using 84cc Stealth heads that have been prepped by Muscle Motors. I expect around 10.5 to 1 compression. I will be using an RPM intake with a 750 carb. I will initally fire it up with a .528 Mopar solid cam. Don't have it built yet but I think that it will run pretty good. It is ready to assemble.

The current plan is to install it in my 64 Dart with a 4 speed and Dana 60. Ultimately I am looking for approximately 450hp.

Good luck,
Mike
 
Well, it looks like the final hardware combination will be this:

KB162 flat top pistons with skirts coated by Swain Tech
Block decked to run pistons .004 down
Edelbrock E-Street heads cut .015 to give 73cc chambers
Comp Cams XE262H cam
Edelbrock Performer 383 intake
Schumacher headers
Holley 600 vac. secondary carb (off the 318 we're running now)

The CR for this combo comes out to just under 10:1, with a DCR of 8.4:1. Should be interesting to see how it runs once its built (probably Sept. since the headers are 8 weeks backordered...).
 
Good luck with that DCR and pump gas on a hot day. I think you're pushin it. It can stand more cam.
 
RustyRatRod said:
Good luck with that DCR and pump gas on a hot day. I think you're pushin it. It can stand more cam.
Click to expand...

What do you think would be a more reasonable DCR ? I thought anything under 8.5 with aluminum heads was acceptable.... If I don't cut the heads and leave them stock at 75cc, the CR drops to 9.78 and the DCR to 8.19.... We already have the cam, so that's not going to change.
 
OK, so now I'll ask the question that everyone building a new engine asks.... how much hp/tq do you think this combo will make?

Once again:

.030 over 383
stock crank
reworked stock rods
KB162 pistons, skirts coated by Swain Tech
block decked for pistons .004 down
Comp Cams XE262H
Edelbrock E-street heads with 75c chambers
Edelbrock Performer 383 intake
Holley 600 cfm vac. secondary carb
Schumacher headers into 2 1/2 inch dual exhaust
Compression ratio of 9.8:1
Dynamic CR of 8.2:1

Thoughts, anyone..??
 
i just don't know how much hp but when you put a bigger carb, something like a 750-800 on it it will like it a bunch more and make more hp for sure.

my 318 bored +.060", somethinglike 321" with 9.9-1, stock 360 heads, a towing cam and the stock 4v factory holley on it didn't like regular gas at all. it ran and towed great premium though.
 
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