how much nos will kb-107 safely take

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360moparjunkie

360moparjunkie

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Hello all....forum still awesome and great to be back!..

I have freshly machined, balanced, resized 360 w the rhs heads and healthy cam....kb-107 pistons...its ready to paint and put in. HOW MUCH HAS BEEN SAFELY SQUEEZED W THESE PISTONS?

Ive heard from non mopar racers my new hyper pistons wont hold up and will melt with the juice. I want to be reasonable on shot size so ive pulled jetting for nos down to 75 shot on my current running engine.

Im experimenting with my current running motor in the 73 dart. Current 360 wich has big cam, exhaust j heads n 456 gears, 727. This is the motor my car came with. It seams to take up to 140 shot no prob but internals are unknown. Very cool motor just oil press falls from 45psi to nada once used and warmed up at idle.

Thnx!
 
360moparjunkie said:
Hello all....forum still awesome and great to be back!..

I have freshly machined, balanced, resized 360 w the rhs heads and healthy cam....kb-107 pistons...its ready to paint and put in. HOW MUCH HAS BEEN SAFELY SQUEEZED W THESE PISTONS?

Ive heard from non mopar racers my new hyper pistons wont hold up and will melt with the juice. I want to be reasonable on shot size so ive pulled jetting for nos down to 75 shot on my current running engine.

Im experimenting with my current running motor in the 73 dart. Current 360 wich has big cam, exhaust j heads n 456 gears, 727. This is the motor my car came with. It seams to take up to 140 shot no prob but internals are unknown. Very cool motor just oil press falls from 45psi to nada once used and warmed up at idle.

Thnx!
Click to expand...

if you don't have any oil pressure at idle when warm you need to do something with the 360 before it grenades itself, anything under 10 PSI and I would be worried
 
My buddy built a 360 for his cousin and knowing he was kinda "daring" he put a bunch of gap in the rings. Long story short the cousin ended up shooting a 300 shot through the motor and it lived for about 6 years.
 
I agree about getting the oil pressure seen about first. That said, instead of relying on chebbie guys and forum geniuses, what I would do is call United Engine. Since they make the KB pistons, they can best tell you how much they can stand and how to set them up to do it. The ring gap is critical. If the engine is already together and you did not set the rings up for nitrous, you better not do it unless you come back down with it and either file the ring gaps wider or set it up with new rings with the correct gap. I always like talking to Marco at United Engine. He's a nice guy and knows his stuff. Call them. That way, you don't have 50 different opinions that may all end up being wrong.
 
I think you can get by with a little more than a stock piston - they are stronger than plain cast. But - you MUST gap the rings per their instructions or you'll break the tops off them - not from juice - from heat. They don't melt - they fragment if you go into detonation or ping. The standard cast pistons can absorb the shock from pinging and detonation. Hypers can't. It's like a screwdriver vs a chisel. The chisel's stronger but much more brittle.
Or call Marco.
 
I put 925 passes over 5 years, on my 360 with the KB's before 1 piston crumbled.
Had a 125HP shot on it.
We only used the NOS in case the car spun.
It ran 11.30's & could run 10.80's with the juice flat out.
The piston gave no warning, that is was leaving town.
Matter of fact, it ran as well as it ever had, & failed after he let out of it in the traps.
Good bye Edelbrock heads.
 
I worked with Marko, with a "k", back in the early 80's Sharp guy.

Ring gap is the deal on hypers. The pistons will take a 150 shot pretty easy as long as you have a good tune up, not the real fat, junk jet recommendations in most kits.
 
Riding the same wagon here about ring gaps, and wall clearance. As long as you set it up correctly, and borrowing from the FAQ page from the old KB website, you can run nitrous. They don't specify an amount, but they do state through testing they did safely run power adders when the ring gap and wall clearances are appropriate.

I tried to access the old website, but for some reason I can't open it--if it were me, I'd probably call up UEM and tell them your plan.
 
crackedback said:
I worked with Marko, with a "k", back in the early 80's Sharp guy.

Ring gap is the deal on hypers. The pistons will take a 150 shot pretty easy as long as you have a good tune up, not the real fat, junk jet recommendations in most kits.
Click to expand...

Tell him I apologize for misspelling his name. lol
 
I've talked to him a lot. He's probably one of the nicest guys in the business.
 
crackedback said:
I worked with Marko, with a "k", back in the early 80's Sharp guy.

Ring gap is the deal on hypers. The pistons will take a 150 shot pretty easy as long as you have a good tune up, not the real fat, junk jet recommendations in most kits.
Click to expand...

I requested max gap on my hypers to my builder. Piston to wall clearance im not sure. Builder had pistons in hand before machining to bore appropriately w knowledge the motor will be ran hard.

Good to hear some success on 100+ shot without immediate piston failure. :)

Once new motor is installed I will gradually work my way up on jetting. Hope it runs great w/o the juice. Few of my key parts came from and recommended by Brian. :D
 
txstang84 said:
Riding the same wagon here about ring gaps, and wall clearance. As long as you set it up correctly, and borrowing from the FAQ page from the old KB website, you can run nitrous. They don't specify an amount, but they do state through testing they did safely run power adders when the ring gap and wall clearances are appropriate.

I tried to access the old website, but for some reason I can't open it--if it were me, I'd probably call up UEM and tell them your plan.
Click to expand...

Would like to see that once found. TY.
 
mikedevore said:
I put 925 passes over 5 years, on my 360 with the KB's before 1 piston crumbled.
Had a 125HP shot on it.
We only used the NOS in case the car spun.
It ran 11.30's & could run 10.80's with the juice flat out.
The piston gave no warning, that is was leaving town.
Matter of fact, it ran as well as it ever had, & failed after he let out of it in the traps.
Good bye Edelbrock heads.
Click to expand...

Hope my new motor pushes that good once stabbed.

Know what they say "running best before they blow"

Built Motors do cost some bucks!
 
In the installation instructions section on their site.

[ame]https://www.uempistons.com/installation_instructions/kb_installation.pdf[/ame]
 
That's only part of what I was looking for...on the old website, there were a few articles that I couldn't locate on the new one. Some took forever to read through, but very informative.
 
The instructions that came with my 107's had a formula that you had to use for caculating ring gap for intended useage.
Blowers / Nitrous required more ring gap from what I remember.
 
Definitely more ring gap for the spray.
I read in the Car tech (the publisher who took over S-A design) bok "how to use nitrous oxide injection for maximum perfromance" by joe petitt, that nitrous enhanced detonation is the perfect frequency to shatter hyper pistons.
They say 150 is a safe ceiling. Like anything, get everything right, and you'll get away with lots.
Get something wrong, and you'll get a sump full of piston.
 
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