nitrous oxide on a hypereutectic pistons

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old school

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Anyone out there ever ran any nitrous on Keith Black hypereutectic pistons? I've got a mild 1978 360 stock heads,mild cam and flat top Keith Black hypereutectic pistons. I am wanting to add about a 100 or 150 shot of nitrous. Will the pistons hold up to the gas. These are cast not forged pistons. I've heard it doesn't take much to shatter these pistons. Just want to see what it will add to a Duster going down the track. Would like to make it into the 12's. rear end is a 8 3/4 with 391 gears and a 727 trans. Any ideas out there. I know some one has tried this before. Mayb I can learn by your mistake if it is a mistake. Thank Old School
 
Pistons will hold up....IF....You pre gapped the piston rings for nitrous like KB says to. If they are in the car already, you won't live long spraying on them.
 
The tune up needs to be good and stay out of detonation.

Gap needs to be wider on top.

That current set up should be close to 12's if it's got a decent converter and tune up. It needs to 60'...
 
This topic always come up and there are thousands of opinions. A 100 shot is by far the safest to use. I have had extensive conversations with Holley (NOS) and my local speed shop. I was assured and reassured that my Magnum 380 HP crate motor (Hyper pistons) would safely handle the gas after the motor was broken in. People will say to run a seperate fuel system, retard the timing,run this or that plug, rich, lean etc. etc. I wanted a system I could safely use without changing this or that and hands down I was basically assured that my system was perfectly safe with my set up. All I have to do is manually purge at the throttle and I am good to go.
 
The motor is together and running for a year. I set the gap for the rings at .018. Thanks for the opinions guys. Old School
 
w2360Duster said:
I myself wouldn't chance it, those KB pistons have a tendancey to destruct under normal use. just my opinion:eek:ops:
Click to expand...
I disagree, they dont "destruct under normal use" if they are gapped and used properly. Even the best piston in the world can be broken by improper clearance, poor assy, overheating and detonation.
 
old school said:
The motor is together and running for a year. I set the gap for the rings at .018. Thanks for the opinions guys. Old School
Click to expand...

You used the ring manufacturers suggested gapping which is wrong for KB hypers. I've seen KB's rip the top of a piston off in normal street driving using the .004-.0045/inch gapping most ring manufacturers recommend.

The gap on top ring for a 360 should be in the .026 area for street driving.

It's a grenade waiting to go off running juice on that ring gap. Gap for light juice use is around .032 for KB's

See the second page for ring gap factors.

[ame]http://kb-silvolite.com/assets/kb_installation.pdf[/ame]
 
crackedback said:
You used the ring manufacturers suggested gapping which is wrong for KB hypers. I've seen KB's rip the top of a piston off in normal street driving using the .004-.0045/inch gapping most ring manufacturers recommend.

The gap on top ring for a 360 should be in the .026 area for street driving.

It's a grenade waiting to go off running juice on that ring gap. Gap for light juice use is around .032 for KB's

See the second page for ring gap factors.

http://kb-silvolite.com/assets/kb_installation.pdf
Click to expand...


Bingo
 
crackedback said:
You used the ring manufacturers suggested gapping which is wrong for KB hypers. I've seen KB's rip the top of a piston off in normal street driving using the .004-.0045/inch gapping most ring manufacturers recommend.

The gap on top ring for a 360 should be in the .026 area for street driving.

It's a grenade waiting to go off running juice on that ring gap. Gap for light juice use is around .032 for KB's

See the second page for ring gap factors.

http://kb-silvolite.com/assets/kb_installation.pdf
Click to expand...
**** it's a grenade waiting to go off now,that engine gets warm its gonna be by by top ring lands.....i gapped mine at 26...
 
Yup should have been a sheet that came with the pistons...

[ame]http://www.kb-silvolite.com/assets/kb_installation.pdf[/ame]

Sucks to find that out now but at least you can fix it before the engine blows up

Whoops nvm crackedback got it...
 
crackedback said:
You used the ring manufacturers suggested gapping which is wrong for KB hypers. I've seen KB's rip the top of a piston off in normal street driving using the .004-.0045/inch gapping most ring manufacturers recommend.

The gap on top ring for a 360 should be in the .026 area for street driving.

It's a grenade waiting to go off running juice on that ring gap. Gap for light juice use is around .032 for KB's

See the second page for ring gap factors.

http://kb-silvolite.com/assets/kb_installation.pdf
Click to expand...

x3...
 
your best bet is to put time & money into planning your next engine. the $300 for the nos kit you could find another block to start your new build. maybe plan out a 500hp SB (it sounds like you like smalls) and go from there. enjoy drivin the car now like it is, believe me it sucks when your abody is not roadworthy :( mine's still getting body work 14 months and counting.

if you spent $$$ on the nos and whacked your engine you would be in the same boat that i am in. cant drive it.
 
I have the sheet that came with the pistons, I gaped them to what it said. I just thought I had set them to .018. Thats what I'm used to setting regular pistons at. But if it blows, I've got a 1999 magnum with 90,000 miles on it hanging on a stand that I've been wanting to build anyway. I guess I'll use forged pistons in it. Thanks for the info guys I guess well find out in a couple of weeks. I'll take it to test and tune for a couple of weeks and break it in some, before i put the gas to it. Thanks for the info guys
 
If it's basically new, you could just stick a new set of rings in it... I'd pull it out but you could do it in the car if you had to... Just a thought. I'd rather drop a hungie on rings and gaskets than plan a funeral. Just my opinion anyway...
 
Something to consider my Kb pistons came with rings that were already at least .026" I barely opened them up when I put my engine together (.035 or so), yours would probably be the same but who knows
 
crackedback said:
The tune up needs to be good and stay out of detonation.

Gap needs to be wider on top.

That current set up should be close to 12's if it's got a decent converter and tune up. It needs to 60'...
Click to expand...

Couldn't have said it better.

crackedback said:
You used the ring manufacturers suggested gapping which is wrong for KB hypers. I've seen KB's rip the top of a piston off in normal street driving using the .004-.0045/inch gapping most ring manufacturers recommend.

The gap on top ring for a 360 should be in the .026 area for street driving.

It's a grenade waiting to go off running juice on that ring gap. Gap for light juice use is around .032 for KB's

See the second page for ring gap factors.

http://kb-silvolite.com/assets/kb_installation.pdf
Click to expand...

Yep. I have put as much as 350 on a hyper motor. It made 800 total and it ran well until a solenoid stuck and shattered almost all the pistons.
 
The Cartech book "How install and use nitrous oxide for maximum performance" by Joe Pettit, claims that the frequency of a nitrous oxide fed cumbustion is bang on correct to shatter them.
I'd like to hear from more people who have run the spray on hypers, as I'm toying with the idea of doing the same.
 
Ok Guys You've scared me. I won't chance any gas on this motor and I'll know better next time. That's what this forum is for. Thanks Od School
 
One year isn;t much, I doubt if the gaps opened u much if it all.

I got 2 years and 5,000 miles on my hypers and ran it as hot as 210--most times 180-190 in the summer. So far all good with a 6,300 shift point..it has been to 6,500 a few times--once in 3rd gear, lol

My builder told me to never run nitrous with those hypers, he built the short block and didn't say what he gap them at expect he likes large gaps and loose bearing clearances
 
I have sprayed upto a 200 shot on an old school Mopar Performance reman 360 short block. They had hyperutectic pistons, Im pretty sure they were Speed Pro pistons. I did make several passes with a 150 shot. And I was also running 6psi of boost from a Roots style blower. Lol
I had alot of street time with a 75 shot, to act as an intercooler and to make for a dense air charge.

The skirts failed on 3 pistons from hi RPMs, IDK how many RPMs as my tach only goes upto 8000.
 
I put 925 passes on my KB's in my 360 before it lost a piston.
Built this engine on 03/31/07 & the piston failed 03/31/12.
I used a 125HP shot on it early on in the second season, ran some 10.80's in street car.
This engine was built to be a street engine & ended up in a race car.
There was absolutly no warning when the piston failed.
It failed at the end of the first pass of the 2012 season, killing my Eldelbrock heads.
The short block can be repaired with a sleeve, the wrist pin still moves freely in the rod on the failed cylinder.
I would advise using a forged pistons.
 
The issue with gap is all about the Keith Black hypers. Other manufacturers use a lower top ring and a different alloy. So the Speed Pros are fine up to their breaking point (although detonation will hurt them just as easy).
 
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