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Discussion Starter · #1 ·
A friend is telling me that more than a 150 shot of nitrous or more than 5 psi from a supercharger will cause the hyperutetic (sp?) pistons used in the newer Vipers to crack. The older Viper used forged pistons and can take more.

I find it hard to believe that the Viper engine is just 150 HP away from destruction.

I hear there is no knock sensor in the Viper's system.

Maybe N2O and or boost with aggressive timing and low octane fuel???

What gives? There are lots of people running lots of boost in much smaller engines with hypers and not breaking.
 

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Discussion Starter · #4 ·
Slow Eddie I already mentioned some things about it to him. He said then why will none of the tuners go more than 150 shot or 5 psi on the hyper motors?

He has a supercharged Viper and he is one to do some research on any of his toys.

It all started when i found a few cracked Speed Pro Hyper pistons in my engine.
 

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Yellow Fever said:
DChan415 said:
Paxton has a kit for newer cast piston Vipers that bumps up power 171HP at 6-7 psi. www.paxtonauto.com

The horsepower isnt what kills pistons... heat kills pistons.
Incorrect TUNING and IMPROPER A/F ratios KILL Pistons
:stupid: if the tuning is right, then it will last....as long as you give it enough fuel, and keep the motor cool your set(for the most part)....My mustang could take a 150shot with the right tuning. And i promise the Viper motor is MUCH stronger than a 302W motor...


Anthony
 

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The stock Viper engine will take more than an extra 150hp on heads and cam etc, but when you add Nitrous or boost the bets are off. Some get away with it - some don't - but understand this....

some of those that fail had a safe air fuel ratio and plenty of timing pulled from what I've gathered asking around.

The problem is not engine strength it is the location of the top ring land. It is very high - which is great for all motor - bad for boost and the violent power of Nitrous.

Anyone adding either to the cream puffs does so at their own risk. Personally I would build the engine and replace the pistons rather than wait for the big bang.

I know some cars have taken it - but to say all can is wrong and you will take their advice at your own risk. You could take a cream puff car and add 5lb boost or a 150hp shot, then add a sophisticated ECU and spend MANY hours of tuning and that would still be no gaurantee!
 

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Torque is right on. I've been running the 5 lb Roe blower for 1,000-1,500 miles and decided to upgrade my creampuff before I had a problem. Much to my surprise, this is what my no. 3 piston looked like when we pulled them:

[image]http://imagehost.5gigs.com/uploads/R%20RANGE%20%20VIPER%20GTS%20JUNE%202004%20070.jpg[/image]

There just isn't enough material above the ring.
 

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Discussion Starter · #12 ·
RedGTS that looks like the picture my friend sent me when I mentioned my cracked hyper pistons. How did the head and valves fair? Unless it came apart in pieces it looks like something else may have gotten tweaked! -ouch! It looks like a classic knock caused failure.

Good excuse foe some forged slugs. Maybe at a lower CR for more boost?

Torquemonster Good point about the position of the first ring.

I still believe a knock sensor would be a good idea - KNOCK breaks parts. Every knock does a bit of damage that eventually will cause a failure
 

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I only dyno'd 600 RWHP & 788 RWTQ on my last pull. I didn't have the propane nor the nitrous tank warm enough. It's pulled 646 RWHP & 818 RWTQ best.

Is that over 150 more than stock on a 2000 GTS....uhmmm probably note.....

Carl
 

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11sec, amazingly enough, there was no sign of damage on the head or in the bore. The electrodes on the plug were pushed in just slightly, and we speculate that the piece(s) hit the plug and went straight out the exhaust port. My new heads are 9.1 compression, so with forged pistons it should be a much more suitable combo for boost.
 

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So what's involved in a piston swap, parts and labor wise? Does someone make a set of forged pistons you can just pop on the OE rods with new rings and you're done?

Do you have to hone the cylinders for the new rings (I suppose you do)

Depends on how many miles on the cream puff I suppose..

Or..?
 

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So what's involved in a piston swap, parts and labor wise? Does someone make a set of forged pistons you can just pop on the OE rods with new rings and you're done?

Do you have to hone the cylinders for the new rings (I suppose you do)

Depends on how many miles on the cream puff I suppose..

Or..?
You're on the right track. There are forged pistons you can use with the stock rods (and new rings of course), and on a low mileage car with clean bores a bead hone with the engine in the car should work, assuming it's all done by someone who knows what they're doing. The question is, how much power do you really plan to make, and depending on the answer to that question, how many other things should you consider upgrading while you've got the engine apart. At a minimum it would probably make sense to upgrade the lifters to a non-bleed down version.
 

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and you should always hone the cylinders and replace the rings when you remove the pistons from their bores...it's next to impossible to get the rings back in exactly the same place...and they seat to a certain wear pattern on each cylinder...Len
 

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Seems like someone ( a shop owner?) recently replied to this subject on another thread saying you could do it 'in frame'.. but with honing required (of course) and all that honing solution contaminating the lower end (not to mention the engine compartment) I'd think the block would have to come out to get it squeaky clean afterwards wouldn't it?

Hmm I could swap heads, add the Al flywheel, and forged pistons all in one long tear down. Oops..camshaft too!
 
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