Warning to Nitrous users !!!

[PBJ]

Hey Guys,
I had a little problem with my car the other night while horsing around. I had a T&D rocker break in half on the exhaust side of # 8. This resulted in the pushrod dropping into the block and hitting the connecting rod which pushed it into the bottom of the piston. It looks like a grenade went of in the inside of my motor. Everything is repairable with no major problems... thank god for having spare parts with the help of my friends. Anyway, my reason for posting is, I called T&D about the problem. When I talked the tech he knew exactly what happened before I told him....he said that their aluminum rockers are only designed to last a season or two before failure on nitrous. He said the additional heat and cylinder pressure causes them to stretch and break in half on the exhaust side. He said you can send in your rockers and they will check them for free....maybe we should all send them in this winter while the cars are sleeping. I would hate to see this happen to anyone else. I have been using T&D rockers for a long time and I have never had a problem, but I guess there is always a first time. To give you a idea or time frame on how long mine lasted, I have been spraying my car for over a year and have used at least 60-70 bottles of nitrous. The nitrous has broken every other piece on the car...transmissions, rear ends, half shafts...etc. This is the first engine related problem I have had. So just beware guys.
Later,
Joe

 

[FE 065]

I'm not sure why additional heat and cylinder pressure, - inside the cylinder, causes a rocker arm to stretch and fail...because the exhaust valve train is facing higher exhaust valve opening (EVO) pressures?

Is there a difference in cylinder pressure between a stock engine with a 100 shot making 525hp, and a n/a engine with no nitrous making 525hp? Are high horsepower non-nitrous n/a engines at risk as well?

 

[GR8_ASP]

Higher cylinder pressure will indeed apply more load on the valvetrain, especially the exhaust side. In effect the exhaust valve must push open against a higher force right at the opening point. If you have a higher cylinder pressure, then you must have a higher cylinder pressure just before blowdown or exhaust valve opening. heat transfer and expansion are the primary causes for pressure reduction as it goes from TDC to BDC.

Not sure I understand the temperature argument as N20 generally uses a high enough fuel air ratio to actually reduce peak cylinder temperatures.

The bottom line is I have observed many engines having exhaust side valvetrain problems as the performance wick is turned up.

 

[Fast Freddy]

60-70 bottle of nitrous is alot. especially in just over one years time. if you are using a 15 pound bottle like i think you are that is an average of 650 pounds of nitrous assuming you refill your bottle when you get down to the 5 pound full mark. did you bother to adjust your valve train geometry at all in the last year? if not i could see why you would have a rocker arm failure at that point. nitrous likes and works best to have a dual pattern camshaft with more lift and duration on the exhaust side. i assume you are using such a cam. also how much nitrous are you spraying? i am gonna assume you are spraying a 250 hp+ shot with that much use in just over one years time, especially considering that fact that you have broken all of your drivetrain components. if i was you i would get jesels new steel roller rockers. they are the strongest and best engineered rockers in the world. the mounting system is more rigid than the t&d mounting system as well.

 

[PRVT JET]

You are not going to break half shafts or transmissions on street tires, I think the stickier tires put more pressure on the rest of the parts.

 

[FE 065]

I read a recommendation recently that racers with high lift cams & hd valve springs etc remove their rockers if the car sits for extended periods between races, or over the winter, to prevent some cylinders' valve springs from inadvertently being parked at full compression too long and weakening the spring/putting extended high loads on that part of the valve train. Or at least turn the engine over frequently.


Though the 1.7 ratio may not be a huge increase in ratio, I'd assume it does put more tension on the spring and therefore the Al rocker at a given lift compared to stock, especially at full lift/compression.


It might be prudent to bump the engine over on days you're not driving it if you have Al rockers.. (ounce of prevention)

 

[PBJ]

Hey guys,
I have 2 10 pound bottles and run on drag radials all the time. I have a split cam for nitrous that comp cut for me and I check my lash on a regular basis. Maintenance is not the problem. There are a whole bunch of us here in St.Louis that street race on a regular basis. It is not uncommon to go through 2 bottles in one night, I run a 200 shot and keep my pressure over 1150 at all times. I have also been to all of the v 10 nationals except Florida and race at our hometown track on a regular basis. I went through 7 bottles in Bowling Green this year alone, I know customers of mine who go through more nitrous than I do. The car definitely gets abused, it is not a trailer queen. I would say that the drag radials are as hard or harder on the drive train than the street tires. If you can keep the wheel hop down on street tires you won't break that much. The drag radials don't flex and they hook hard all the time. At least a slick the sidewall gives a little and seems to be a little easier in the driveline. My car cuts consistent low 1.50 sixty foot times on the spray with a best of 1.49...this is all on BFGs. That is why I have broken all of the stuff I have...in my opinion anyway. Anyway, I just thought it was weird for the rocker to break the way it did, I have never seen that happen before.
Later,
Joe

 

[2MANYTOYS]

Thanks Joe! Good info...

 

[ChicagoGTS]

Crap, do you think this applies to people wanting to run a small shot on top of a blower, or is it just related to the quantity of No2. I've never driven a sprayed car so I don't know the temp difference. I wonder if propane enrichment help this problem? I'd be curious to see how many people have had this issue that have been running BTR's propane setup with T&D's for an extended peiod of time.

~Matt~

 

[V10 MOJO]

good info Joe; i personally plan on a complete inspection this winter. especially since ill be doing a stroker upgrade.

 

[DEADEYE]

I really hate to resurect an old post but this topic is of concern to me. Has a cure to the problem been found?

 

[TOOOFST]

The truth hurts and most high power tuners won't spell it out.Thanks for posting.T&D could be really nice guys and replace it,sounds like the basic that's racing.I wonder what other no/no's they neglected to tell!Good running with 60-70 bottles through er.

 

[plumcrazy]

hhmmmmm

 

[IEATVETS]

Maybe a defective part?? I know a lot of people that run nitrous and have never heard of that. But then again, they don't run that much through there car either. Good info to know though.

 

[sun diego]

It happened to me. My engine is being rebuilt. I have used similar amounts of nitrous.

 

[joe117]

Get some steel rockers. The inertial weight saved by making the rockers out of aluminum isn't much.

I also remember that aluminum connecting rods are only good for a certain number of hours use. They flex a little and this causes cracks.
At least they used to be rated this way. They can only take so much before they break. They could be used in a very high powered dragster for a certain number of runs but using them in a street engine wasn't a good idea.

I wonder if the added strain of 1.7 and heavy spring and opening pressure against the increase nitrous gives,
Bring the aluminum rockers to the point where they, like aluminum rods, only last so long.

If that's the case, they should be replaced at intervals.

I'd rather use steel or titanium if you think that would be worth the money.

 

[Camfab]

Based on the response from the manufacturer it sounds like they are to be replaced once a season. In the Small and Big Block Chevy world this was a big problem along with bearing failures about 20 yrs. ago. The failures tended to be in the trunnion area. In all fairness though, anytime your thrashing on a car your going to find the weak link. Nitrous just helps you find the problems much sooner. Inspection is very important and aluminum unlike steel strethces very little before it fails.

 

[joe117]

Exactly what is there to be gained by aluminum rockers. The Viper V10 isn't turning any high rpm. The valves shouldn't ever float.

There isn't any reason that I can see for aluminum rockers.
And now that at least a few people have damaged engines because of this aluminum part,

why would anyone use them?

 

[Jerry Colpitts]

Jezel Rockers / Awesome

 

[JonB]

You are not going to break half shafts or transmissions on street tires, I think the stickier tires put more pressure on the rest of the parts.

Not so fast..... THE YEAR MATTERS !

You MIGHT Break half-shafts

 

[plumcrazy]

jonB, what years are you talking about ?

 

[dblankenbaker]

Early years... '92, '93, maybe '94. (my '95 had beefier halfshafts from the factory)

 

[BlueGTS]

Can someone explain why a NX car would be more prone to this failure versus a SCed car? I would think the cylinder temps would be less in a NX car versus a ROE car for example.

 

[DEADEYE]

You'd think that since N20 is used waaay less than any other power adder that it would be the last to expose this problem. I might leave the car to H/C and bolt on mods only.

 

[pedro]

I just purchase a set of t&d 1.7 rockers the rockers have a blue color on them.I looked on roe web site they have t&d rockers and they are not blue in color are there diferent rockers out there????

 

[viper spray]

I just purchase a set of t&d 1.7 rockers the rockers have a blue color on them.I looked on roe web site they have t&d rockers and they are not blue in color are there diferent rockers out there????

Same rockers , you have the "special" Mopar T&Ds.

 

[George Bryce]

When you go to the next NHRA race, check out the fuel cars. Look at the difference on the ex side. You can see everything....they take it apart right in front of you. On our turbo bike engines, we treat the two sides like two different engines. Our intake side is blown open, a stock Suzuki valve spring may only have 25psi seat pressure. When we run 20 psi of boost....well...we end up with only 5psi holding the valve shut. So we put springs in with 45psi of seat pressure. On the EX side, every thing catches hell, valves, spings, rockers or lifter buckets, cam lobes, etc. The intake is blown open, the ex opens at or near peak cylinder psi! This is over 1000psi!!! Imagine if you can, what the pushrods must do to open the EX. verses the intake. The nitro cars have everything bigger on the ex side. Just some FYI stuff.

GB3