Best piston for street/strip 340?

-
I'm not sold on the kb's. They are a great way to make power and are left / right valve reliefs. I just replaced kb 107's with speed pro pistons in a 360. This motor had a little over 10,000 miles on it and popped the ring land of at the valve relief. They were gapped just they way the instructions said and timing was set at 32 degrees total. The top ring is very close to the top of the piston and takes more heat. I would run them again but it would be a race only application where I new for sure what my fuel octane was. I now others have had good luck with them in daily drivers and that's what we would expect, just not for me.
 
Fellas, he is running a stock stroke 340, not a stroker.
 
Keith Black Hypereutectic

'KB-243'

Proven durability, and a good performer for the Street/Strip application.

The Best 'Bang-for-the-Buck'.

Flat Tops ................. 2 Valve Reliefs {-6.0 CC volume}
Ring Lands .............. 5/64" ~ 5/64" ~ 3/16"
Compression Ratio .... 10.2-1 {w/ 68.0 CC ~ Combustion Chamber}
Piston Weight ........... 585 Grams
Pin Weight ............... 132 Grams

Price Cost ................ $295

In our Machine Shop we've built many 340's with this Piston application, and have never had a problem.

And we've done many 're-freshen jobs', and we've never seen a bad slug during a tear down.
 
I have been trying to keep up with a couple related threads,
340 Stroker Build Need LOTS of Advice
and
A few questions about stroker small blocks
Since I started my project I was convinced I wanted a stroker esp since a buddy of mine gives me loads of **** about just having a small block. I remind him that at least I have a classic car.
Anyway, life changes are having me think about scaling back cost to finish, & rethinking stock stroke option, but getting most bang for buck without being cheap about it.
I was interested in MRLs last build,-stock stroke, but longer rod-shorter piston. I now think it might be prudent just to keep as stock as possible, but use "newer thoughts & materials" for my gains. Lighter pistons, less friction, etc. In my reading I remember seeing Total Seal Gapless rings a few years back. The gains weren't huge, but it seemed like sound logic, & not a huge cost. Lighter pistons, less friction don't offer huge gains on their own either, but combining as many small gains as possible will add up.
Does anybody have experience and/or recommendations?
 
Blue printing the motor and have the cam degreed with help. Double roller taming chain, good port and blend in the head. Gasket match the intake and head. Good quality header. Good ignition setup. I windage tray or crankscraper in the bottom will prevent a small loss of hp and keep oil where it needs to me. If you have the spare coin, get a roller cam. A roller cam brings you into the power curve sooner and keeps you there longer.
 
Captainkirk said:
What do you guys consider the best piston (best price considered) for a street/strip 12 second 340?
I have heard some negative reviews on the Keith Black Hypereutectics shattering...although some or all of this could be internet rumor.
Wisecos are little bit outside my tax bracket
KB's..well, see above
Speed Pro?
Any others I may be overlooking?

10-11:1 compression range....
Click to expand...

I've never shattered a KB hyper.

Who here has shattered a hyperutectic on a good tune?

Who here has shattered one from too much timing on pump gas street/street driving?

You can ping them on unleaded and they'll take it for a while, longer than credit is given.
I've hammered mine in my 410 during the tune process a few times, no issue.
I did have a spacer gasket leak that caused idle speed drop, fixed that.

I'll say like this...
The last 5 motors i built and sent out into the world were all KB hyper piston equipt in the 9.6-11 compression, "2 360's and 1 408" were quench domes with .028-.035 quench, the other 2 are KB243... one a 318 bored to 4.040 and the other .030 over 340 sitting in the late spinmans '69 dart which he rode hard and put away wet for a yr or so before he passed into mopar heaven. To this day...no issues.
It's your money...so what keeps you from spending it on what "some" say are the "best",
Is it common sense by chance? ;)
 
Last edited:
MOPAROFFICIAL said:
I've never shattered a KB hyper.

Who here has shattered a hyperutectic on a good tune?

Who here has shattered one from too much timing on pump gas street/street driving?

You can ping them on unleaded and they'll take it for a while, longer than credit is given.
I've hammered mine in my 410 during the tune process a few times, no issue.
I did have a spacer gasket leak that caused idle speed drop, fixed that.

I'll say like this...
The last 5 motors i built and sent out into the world were all KB hyper piston equipt in the 9.6-11 compression, "2 360's and 1 408" were quench domes with .028-.035 quench, the other 2 are KB243... one a 318 bored to 4.040 and the other .030 over 340 sitting in the late spinmans '69 dart which he rode hard and put away wet for a yr or so before he passed into mopar heaven. To this day...no issues.
It's your money...so what keeps you from spending it on what "some" say are the "best",
Is it common sense by chance? ;)
Click to expand...
Thanks for the reply, but the train has left the station...
I chose the Speed Pro forged pistons on the recommendation of my machinist...
 
The speed pros are fine. Ive taken mine past 7000 many times with stock rods and no problems. Not recommending this just saying.
 
Captainkirk said:
Thanks for the reply, but the train has left the station...
I chose the Speed Pro forged pistons on the recommendation of my machinist...
Click to expand...
Where did you find that machinist, the 70's?
Some heavy pistons. I'm sure you will be happy anyways.
 
Last edited:
Captainkirk said:
What do you guys consider the best piston (best price considered) for a street/strip 12 second 340?
I have heard some negative reviews on the Keith Black Hypereutectics shattering...although some or all of this could be internet rumor.
Wisecos are little bit outside my tax bracket
KB's..well, see above
Speed Pro?
Any others I may be overlooking?

10-11:1 compression range....
Click to expand...
Speed pro's, great pistons for the $
 
Yeah the speed pros are the same as the old TRW. They are heavy alright, but they'll work.
 
I'm sure it will be plenty quick with the Speed Pro's. I won't be racing it anyway. I appreciate all the advice and input, but I chose the SP based on price & reliability. My machinist knows what my end goals are and concurred that the forged SP was the right piston. Matching these with the Eagle forged rods and the stocker forged crank should yield a pretty bullet-proof bottom end for a small-block street motor.
 
I'm not saying that the sp pistons are the best. Just that your engines not going to fall apart because you used them. The 2316s can be set as close as .0015 but I always set them at .003 and have no knock.
 
I prefer forged piston engines to be loose anyway. A little rattle never bothers me. At least I know they ain't gonna seize up. The old TRWs (and I assume the Speed Pros as well) were "cam ground" pistons. In other words, they were not round at room temperature. Once they get to operating temperature, they expand to the proper size. That's why the old school forged pistons would sound like a diesel when cold, but quieten down when warm.
 
As long as we're piling on I'd be more concerned with the Eagle rods...
 
You must log in or register to reply here.
-

Back
Top