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Discussion Starter · #1 ·
Just curious if it's possible to disable or raise the 6200(?) rpm factory cutoff on a GenII car. -And if so how it's done.
I'm NOT going to do it to mine, just wondering what it takes to do it ...
 

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There is no reason to do it, more rpm's does not = hp or speed. it depends on the powerband of the cams. After a certain rpm's the HP drops.
 

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Discussion Starter · #3 ·
Well if that was true F1 cars wouldn't be turning 15,000 rpm would they?

More RPMs do equal more speed btw, do you want the formula?

Without getting into all the endless stuff about cams, porting etc, which it WOULD take of course, or Viper engine theory, OR a pissing match about it..
I just want to know Can the rpm cutoff be disabled or raised ?

If it can, I'm curious how complicated it is. I don't need detailed instructions, just an overview of how it would be done
/images/graemlins/yay.gif
 

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FEO65...aren you nuts? The reason the F1 cars go to 18K RPM (BMW) is because their engines are completely different and refined. A Ferrari F1 engine costs around 300K as opposed to 11K for a Viper engine.

If anyone does decipher the language and codes of the Dodge computer, then that person would be rich....so to answer yor question, no it can't be done and it hasn't been done. The closest person to do anything to the PC is DLM that I can think of. Dodge guards their PC language very closely.
 

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The RPM limit is in the PCM. It limits the RPM because it has control over your spark and fuel injector timing.

There is no way to raise it unless you can reprogram the PCM yourself.

And I agree with others - there is no benefit to raising the RPM. How much do you think you can get? Another 500rpm? I don't think you can without seriously compromising the integrity of the engine.

You talk alot about formulas - do the math on the tensive and compressive forces at play in the con rods and compare them to what those rods are rated for and you will know *exactly* why the RPM limit is what it is.
 

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Discussion Starter · #6 ·
I get it now..I wondered this question instantly had everyone challenging my intelligence (which I knew was going to happen anyway).
I meant to say "I'm NOT going to do it to mine" which I've now corrected with an Edit.

"There is no way to raise it unless you can reprogram the PCM yourself." is all I really needed.

But THANKS for jumping on me anyway.. I've no intention of doing it to mine, but for the record, it's not THAT crazy of an idea.
 

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FE065 said:
I get it now..I wondered this question instantly had everyone challenging my intelligence (which I knew was going to happen anyway).
I meant to say "I'm NOT going to do it to mine" which I've now corrected with an Edit.

"There is no way to raise it unless you can reprogram the PCM yourself." is all I really needed.

But THANKS for jumping on me anyway.. I've no intention of doing it to mine, but for the record, it's not THAT crazy of an idea.
It's not a bad idea on many engines, but on a V10 with a ton of reciprocating mass, it's not a good idea. The V10 already has high-rpm oiling problems as it is, so if you spin it faster, you're asking for trouble.

Now, if you went through the engine and lightened it up, fixed the oiling issues, and maybe de-stroked it, you could run it much higher, but then you'd lose all that low end torque.
 

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Well if that was true F1 cars wouldn't be turning 15,000 rpm would they?
This, Your talking apples and oranges.

More RPMs do equal more speed btw, do you want the formula? The only formula you need to look at is the powerband of the cam if the cam loses hp at 5250 rpm how will making it turn more rpm's make more hp? Look at the dyno sheets people post you will see once it hits the max rpm for the cam the hp goes away.

Look at the powerband of the cam for the viper you will see once it gets to a cartain rpm the hp and torque goes away.

No it isn't a crazy idea but in order to get a real benifit from it you would have to build a new motor, since the rods, pistons, wrist pins and an array of other moving parts weigh to much to get to a high rpm like 7,500 without exploding. you would have to go with a steel crank, titanium rods tooled steel wrist pins and about $40K worth of other parts.

I gave you an honest answer and you come up with with a F1 answer that is beyond common sence.

The fumes from the zano have gone to your head.
 

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Even with 40K in a motor, it will only rev a bit higher and give you maybe 700 HP from it. So the F1 answer does apply since the technology they use (pneunatic lifters, titanium and other materials that are lighter and more resistence) and your point applies as well (lighter materials needed to have a smaller rotational mass so that the engine does not explode). And the F1 cars make 900 HP and do rev to 18K.

Straight from team engineers published by F1 Racing:

BMW: 90 Degree V10 900bhp @ 19200rpm

Ferrari: 90 Degree V10 890bhp @ 18700rpm

Mercedes: 90 Degree V10 860bhp @18200rpm

Ford Cosworth (Jaguar): 90 Degree V10 860bhp @18200rpm (surprise!)

Toyota: 90 Degree V10 855bhp @18400rpm

Honda: 90 Degree V10 840bhp @18100rpm

Renault: 111 Degree V10 810bhp @18100rpm

Ford Cosworth (Jordan, Minardi): 72 Degree V10 810bhp @17800rpm

Maybe the AZ heat is making mirages down there....
 

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He was talking about the stock viper engine then came up with a comment that if i wanted a formula for the rpm to hp ratio he would give it to me and that racing engines rev to blah blah rpm's

Comparing a factory stock engine to a race engine is comparing apples to oranges.

I gave him a straight answer and then in return get a lame poser comment this isn't the VCA bord we give smack where smack is due. :cheers:
 

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brianflynn said:
Well if that was true F1 cars wouldn't be turning 15,000 rpm would they?
This, Your talking apples and oranges.

More RPMs do equal more speed btw, do you want the formula? The only formula you need to look at is the powerband of the cam if the cam loses hp at 5250 rpm how will making it turn more rpm's make more hp? Look at the dyno sheets people post you will see once it hits the max rpm for the cam the hp goes away.

Look at the powerband of the cam for the viper you will see once it gets to a cartain rpm the hp and torque goes away.

No it isn't a crazy idea but in order to get a real benifit from it you would have to build a new motor, since the rods, pistons, wrist pins and an array of other moving parts weigh to much to get to a high rpm like 7,500 without exploding. you would have to go with a steel crank, titanium rods tooled steel wrist pins and about $40K worth of other parts.

I gave you an honest answer and you come up with with a F1 answer that is beyond common sence.

The fumes from the zano have gone to your head.
Right on! Hit the nail on the head! :cheers:
 

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Discussion Starter · #13 ·
This never ends..I shouldnt even perpetuate it.
You said, "There is 'no reason' to do it" (if there's no reason to do it, F1 teams wouldn't be cranking 15k rpms or more- there are reasons to do it or want it),
You also said, "more rpm's 'does not' = hp or speed. (but more RPMs always equals more speed of course,and I offered the formula)
If you weren't making absolute comments I wouldn't have countered them...

Thanks again.. I just asked because there's a Viper owner (who shall remain nameless) on the VCA site indirectly claiming 8000rpm capability, and even though he has aftermarket rods, porting etc, I wondered how easily he could get around the OEM computer's 6200rpm fuel shut off.
It looks like it's highly unlikely he's going above the RPM limiter doesn't it?
 

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AFTERMARKET hence it's not stock, It can be done if you have the programs to do it.

If you go beyond the rpm limit in the powerband of the cam you will not get more speed, look at some of the dyno sheets people post you will see the hp and torque curve drop after the point of where the cams stop making power, yes the engine will rev past that but what is the point.

There is no reason to do it, more rpm's does not = hp or speed. it depends on the powerband of the cams. After a certain rpm's the HP drops. If that isn't absalout then what is.
 

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FE065 said:
This never ends..I shouldnt even perpetuate it.
You said, "There is 'no reason' to do it" (if there's no reason to do it, F1 teams wouldn't be cranking 15k rpms or more- there are reasons to do it or want it),
You also said, "more rpm's 'does not' = hp or speed. (but more RPMs always equals more speed of course,and I offered the formula)
If you weren't making absolute comments I wouldn't have countered them...

Thanks again.. I just asked because there's a Viper owner (who shall remain nameless) on the VCA site indirectly claiming 8000rpm capability, and even though he has aftermarket rods, porting etc, I wondered how easily he could get around the OEM computer's 6200rpm fuel shut off.
It looks like it's highly unlikely he's going above the RPM limiter doesn't it?
You can't compare it to an F1 engine. HP is just a function of torque produced at a given RPM. If you can carry the torque high in the powerband, then you can make more HP, which allows you to run shorter gears. HP and RPM's are all about gears.

The Viper is not a high-revving, engine that makes its torque high up, it's a lot revving, large displacement engine that makes all it's torque down low. Given that, there really is no reason to try to spin it up more. Yes, if you could *safely* turn it to 8,000RPM, you could get more power to your wheels, but I don't think anyone is running 8,000RPM without MAJOR longevity compromises. In some cars, raising the redline 500RPM will allow quicker 1/4 mile times. I don't think that will really happen on the Viper, because since it makes so much torque down low, raising redline by 1,000RPM more isn't going to give you that much more *usable* power, since torque is already falling off.

To take advantage of a higher redline, you would really want shorter gears and a motor designed to breate better at higher RPM's instead of the stocker that breaths well at low RPM's.

So, in theory does more RPM's = better acceleration? Answer is yes, IF the engine and driveline are built around the RPM's the engine can attain. In the Viper, they are not built around a high revving motor, so no, raising the RPM limit will not do anything on a Viper, IMO.
 

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Discussion Starter · #16 ·
MPH = RPMxTD divided by GRx336;..GR = RPMxTD div. by MPHx336;....TD = MPHxGRx336 div by RPM;....RPM = MPHxGRx336 div by TD
GearRatio means overall gear ratio (trans gearxdiff gear) , TD means tire diameter.
I'll just post them in case someone, someday viewing doesn't know them. They're fun to play with. Even without the formulae,it should be obvious that if you can squeak a few more RPMs in any gear your MPH has to be higher in that gear. Rods may 'short out the ignition' (as the Brits used to say),bearing may weld themselves to the crank, and rockers may shake themselves silly, but any additional RPM will give more MPH. (Unless your clutch is slipping) Why do you continue to argue? I didn't really want to compare anything. I just wondered how the guy could run 8000rpm plus. Now you tell me if the guy has/had the program, he could do it... It's just a query you know.. All the science, engine theory, etc. you're all adding into it, I'm aware of, and more importantly, was hoping not to get into. Especially back and forth hair splitting, looking for minute loopholes to argue over.etc When I get my carbon fiber Kevlar re-inforced rods and pistons we'll get into it again /images/graemlins/smile.gif Let's hope for nice weather in Norwalk! I'll be there (spectating this time).. Look for the guy with the pocket protector and calculator in hand.
 

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any additional RPM will give more MPH. This is not true. Stating fact is not arguing. You also have to figure in arodynamic effincy. the faster you go the more air you have to push through and the more air you have to drag behind you. This takes more HP the faster you go. it might take 300 hp to get a viper to go 150 mph it will take another 150 just to get it to go 190 mph.

It's not easy to get a factory body car to do 200 mph thats whay car and driver do tests. it takes over 750 hp to get a fox body mustang to go 203 mph.

Here is an example.

take the 700 hp mustang with a rear 355 gear running 5,500 and it maxes out at 198 mph ajust the rear gear to 410 and the car runs out of the rpm range to make the 700 hp at 177, put in a 327 rear gear and it doesn't have enough hp to push and pull the air the only solotion was to put in the 355 and add another 50 hp just to get 2 more mph out of the car.
 

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On a Gen 2 you can eliminate the rev limiter by installing the Mopar Performance computer.
It does that and eliminates need for the input from the rear O2 sensors, along with changing the fuel and ignition curves.

But as everyone knows the M.P. computer doesn't add any horsepower on it's own.
You have to do other mods to gain any HP.

As it's been said, there's no reason to rev a stock Viper engine any higher when the max HP is at about 5200 rpm. It's way over it's peak HP rpm at 6200 already.
 
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