Chip. Raising the limiter

[klmillard]

Am i right in saying that if you have your car chipped then you can increase the rev limiter?

If so i want to know why you would do this? Isnt the limiter there to stop you causing the engine damage?

Just wanna know as my valver is going to be chipped in a while and dont know if i should extend the limiter.

Kev

 

[DTWD]

As far as I can work out your rev limeter can be inreased sometimes. It depends on what you have done. Of course chipping your car in the first place puts extra wear on it, so increasing the revs a bit wouldnt concern me, not that I ever red (sorry thick white) line it anyway.



Paul

 

[klmillard]

Im just a bit worried about doing this. Is it best to leave the limiter as it is?

 

[DTWD]

Why do you need to move it anyway? Dont you have enough power? Think of us poor RT owners.



Paul

 

[klmillard]

na, you always want more power. Just wondered why people move it as i would have thought that this would be terrible for the engine?

 

[Alex M]

na an extra 500rpm wont harm it and given valvers characteristics, it is worth having them, they are dead revvy and even though power tails off up there it doesnt dissappear completly, allowing you to hold that cog a wee bitty longer. Willys aint so fond of the revs being a longer stroke motor and am I correct in saying there standard limiter is lower than on 1.8 16v. The limiter is a setting on the ECU and when you have your car chipped it is often raised a bit. It makes sense with a free flow exhaust etc to raise the limit as they flow beter at higher rpm and so you will get they most out of it by upping the limiter. Manufacurers set these limits on the safe side for the engine and its power delivery. Before limiters became common, people were over revving engines all the time, its ok as long as period of over revving were of short duration, although of course engine going bang is always possible, but if its warm, in good nick it can be ok to go over manufacturers figure.

 

[derv]

ive had my 16v chipped, it now limits at 7800 rpm but i rarely take it that high, i find it is quickest when i change at about 7000 rpm, seems to fall nicely into the power band again!

 

[RobFenn]

Whats the point though, creating more power in unaccessible regions of the rev range? And will make the engine less reliable..

 

[BenR]

why will it increase wear or be more unreliable.

Its only a few more rpm, you can go more damage from downshifting at the wrong point.

 

[RobFenn]

If it revs more than what the engine was originally designed to do its going to wear quicker

 

[BenR]

why will it wear quicker?

there is ablsolutely minimal amounts of wear in a running engine, most of its at startup. By that reasoning, the diff between 1000rpm and 6000rpm is 6 times the wear? and out engine will be kaput in a short time?

 

[RobFenn]

Well no because the engine is designed to do that..if the engine limit was raised to 10,000rpm it would wear the engine quicker right? So obviously it wouldnt wear as quickly but it would still wear quicker than standard. Just because you dont notice it in the short term doesnt mean it wont happen

??

 

[BenR]

well, 10,000rpm is a diff thing altogether.

It wont be wear as such, itll be damage to the rods and crank which bend/stretch and will slap the head.

But an extra 1000rpm in terms of wear will do nowt, but it wont help the crank. But most engines can live hapilly with an extra 1000-1500rpm on a well balanced crank. But wear, with modern oils, its basically non existent. So, the service life wont be any shorter.

 

[JonC]

From what I understand, raising the rev limit only allows you to hold on to the gears a bit longer. Handy when youre in mid corner you can keep the power on instead of changing gears on the limit.

 

[BenR]

That is PRECISELY the benefit!!!

thank god somebody said that.

Eventhough the power tails off, its still making power, it doesnt drop to zero. You can still keep accelerating, and mid corner at 100mph, a shift might not be the best idea.

Top man Jon

 

[rt172]

Did some AP22 runs last night. Changing gear on the rev limit (mines extended to 6750 at the moment) loses me TONS of time. Not even going to say what happens to 0-60 changing there . 6500rpm was also no good. In the Williams, changing around 6200rpm seems to get the best results. Extended rev limit definitely no good for extra top end power.

However, as mentioned, it is very useful when thrashing the car round twisty roads.

Rhys

 

[Dave Hester]

Would a chipped williams be able to cross the 1/4 mile line in third gear then?

Because i have to change into 4th just before i cross the line which in turn probably loses me about 1/2 a second?

 

[BenR]

IF, you have engough rpm to do i i dont see why not.

 

[Adams_16v]

But doesnt the willy run out of steam at just over 6krpm. ask rhys hes been testing using the ap22 i sold him

 

[Craggy]

jim in short, no! a willy with 6800 rpm limit will do 86-87 indicated, so depemds on your et, i still had to use fourth

 

[Frosty]

I raised rev limit helps you in first gear loads though and improve your 0-60 time. You really dont notice that the car is not pulling hard high up the revs in first and by the time youre in second youll be doing nearly 40 mph.

Other than that you really dont need the extra revs except for the reasons others have stated (significantly the cornering idea).

 

[SteveJJH]

Trouble is with the valver engine - its already revving pretty high. I know you cant really generalise all the time, but ive read that a decent engine in a rally state of tune (not even road) should have a mean piston speed of 3800 feet per second max. The valver is doing 3835 at 7000 rpm.

Just a comment, i dont want to go against anything said already.

 

[McBunny]

just look at F1 engines they idle at about 7k rpm and redline at about 17k (could be wrong on redline)

 

[BenR]

peak piston speeds are achieved just before 90 and 270 deg ATDC and only for a minute amount of time. The mean speed of 3800 fps means the actual peak speed will be FAR higher than that.

The 2ltr Maxi meganes and F2 clios were running about 9500rpm..........

In a ltd capacity, more rpm is the ONLY way to process more air and make more power, simple. You just work at making it tougher.

 

[BenR]

F1s are nearing 19K now and idle about 3.5K........

 

[McBunny]

you can make a 2ltr ford pinto 205 block rev to 10k

 

[McBunny]

anyway revs sound good just think superbikes

 

[BenR]

998 cooper Ss in works trim reved to about 11,000 in the 60s!

 

[Simon172]

i put mine in second gear at 80 racing a Fiat coupe turbo once, oops..... never seen the needle jump so quickly! what a horrible noise "neeeeeaaaar!"

 

[SteveJJH]

Ok Ok, you CAN make these engines rev high, but how long do they last and what construction are they?

F1 engines are the pinacle of engineering, very strong and very light, with very short stroke. they are the b****cks, but they still only last one weekend (if your lucky)

Rally engines and so on are rebuilt regularly, its not something i fancy doing on mine every few thousand miles.

Mines ten years old, and although the valver engine is good, its not a full race engine, and i wouldnt expect it to last very long running much higher revs than it does now.

Before i start an arguement - I agree with the comments made here, higher revs are cool, and it can mean more power if youre set up for it, its just something that could significantly shorten the life of your engine thats all.

 

[Eddd]

Im looking to raise my rev limit as it would eliminate a couple of awkward shifts at the ring.

Just like JonC said. Sometimes you just want to be able to hold a gear a split second longer without it bouncing off the limiter.

 

[Alex M]

Na disagree raising a valver to 7800 limit will not make your engine wear out quicker, assuming everything else is sound. Given the nature of the engine it is not really that much higher and manufacturers are understandably super safe when it comes to these things. Perhaps prolonged spells above 7000 might eventually cause something to go, but I suspect that in day to day use a raised limiter wont damage your engine, unless you start it from cold and hold it flat out unloaded.

 

[RobFenn]

Quote: Originally posted by BenR on 04 April 2003


well, 10,000rpm is a diff thing altogether.

It wont be wear as such, itll be damage to the rods and crank which bend/stretch and will slap the head.

But an extra 1000rpm in terms of wear will do nowt, but it wont help the crank. But most engines can live hapilly with an extra 1000-1500rpm on a well balanced crank. But wear, with modern oils, its basically non existent. So, the service life wont be any shorter.





So it will and it wont?

 

[RobFenn]

Quote: Originally posted by dogmaul on 07 April 2003

anyway revs sound good just think superbikes



Yours wont sound like a superbike at those revs!

 

[Frosty]

Quote: Originally posted by RobFenn on 08 April 2003

Quote: Originally posted by BenR on 04 April 2003


well, 10,000rpm is a diff thing altogether.

It wont be wear as such, itll be damage to the rods and crank which bend/stretch and will slap the head.

But an extra 1000rpm in terms of wear will do nowt, but it wont help the crank. But most engines can live hapilly with an extra 1000-1500rpm on a well balanced crank. But wear, with modern oils, its basically non existent. So, the service life wont be any shorter.






So it will and it wont?

What bens saying is that if you try and raise the limiter to 10k, the inertial forces on the rotating assembly and components will be so great there will be no WEAR, but things will literally TEAR APART! Even the best factory blueprinted car engines dont go that far.

 

[BenR]

this till goin!?

there is no wear problem! sheesh, i best i could run a 8000rpm engine jsut as long as you could at 3000rpm!

its a strength problem, and the 1.8 crank is actually pretty good, as are the rods and pistons. dunno what all the worry is........people seem paranoid that their engines will last only 2 days longer all because of 500 extra rpm!??