Gti6 Revs?

[stegti6 0]

hi guys my first post so be kind...ive just picked up a 205 gti6 over the weekend.i love it and have some plans for it.but at the moment the main question is what does it rev too???? ive noticed the standard 1.9 gti redlines at 6...ive seen clocks on ebay for a gti6 that rev to 7...the rev counter in the car seems to be accurate but what should i rev her to?

[welshpug 1,657]

peak power is at 6.5k, though they will rev to either 7450 for early cars, and 7250 on later ones (the limiter was dropper 200 rpm) though there's no point taking them up this far.

 

peak torque I think is around the 4.5-5k, though it varies quite a bit, cam timing has a big effect on how they behave

[stegti6 0]

ahh... superb,thanks for the reply.

[Rob Thomson 6]

Surely just rev it until it hits the limiter? You'll do no damage at all as long as you don't hold it there all day.

 

In response to WP, I'd be very surprised if the quickest way to drive it isn't to change gear just shy of the limiter in every gear. Peak torque is irrelevent, you want to be developing as much power as you can on average. It doesn't matter if you're past peak power when you change, because you'll be higher up the power curve when you engage the next gear. Thrash the nuts off it.

[Cameron 16]

Hitting the limiter is quite bad for an engine, so I wouldn't if I were you.

[DrSarty 90 1 Cars]

Surely just rev it until it hits the limiter? You'll do no damage at all as long as you don't hold it there all day.

 

In response to WP, I'd be very surprised if the quickest way to drive it isn't to change gear just shy of the limiter in every gear. Peak torque is irrelevent, you want to be developing as much power as you can on average. It doesn't matter if you're past peak power when you change, because you'll be higher up the power curve when you engage the next gear. Thrash the nuts off it.

 

Well there perhaps is one answer to your question elsewhere about how you could improve your lap times Rob.

 

Surely it makes sense to capitalise on the engine's comfort zone where it produces most power and up to that point, rather than the other side of the hump where the engine is starting to starve for one reason or another, and components are getting closer and closer to failure due to either physical forces or heat or both?

 

I'd find what makes your engine perform best rather than aim for a certain figure.

 

As an anology, in mud or ice you don't accelerate any faster with more throttle, because you're not applying the forces efficiently to the road. I cannot see why it wouldn't be any different further back up the power chain, i.e. finding the conditions which apply the most force to the road wheels which can actually be translated into forward motion.

 

It's like getting the best from a woman isn't it? We only take them to dinner for one thing!

 

[dcc 855]

I think its important to remember that the gti6 engines behave very much independant when compared to a mi16 or even the good old 8v'ers, the power development is far more linear and the power band (eek could get this wrong) is somewhat wider from what I could tell by reading threads here. I felt I had to keep my gti6 in the higher revs to keep it 'alive' though my mi16 seemed to be far happier being driven from 2k-5.5k with WOT, where are i felt the gti6 was onyl happy here with slight throttle, only really used WOT from about 4k+

 

The engines will rev happily all day long, but sometimes they can turn to chocolate without you even realising and in a split second you are looking at a small fortune! (keep it off the limiter as best you can )

[welshpug 1,657]

Behaviour like dan said, is quite different to an Mi or 8v, unless the cams are retarded slightly they don't scream all the way to the limiter, I have advanced my inlet cam so it dies off even more once past 6600 or so, but it pulls far stronger at 4-5k.

 

They die down very quickly after hitting peak power at around the 6.5k mark, so holding on to the gear for another 900 rpm or so is rather pointless, change gear at 6500 and you'll make far quicker progress.

[dunc 0]

In response to WP, I'd be very surprised if the quickest way to drive it isn't to change gear just shy of the limiter in every gear. Peak torque is irrelevent, you want to be developing as much power as you can on average. It doesn't matter if you're past peak power when you change, because you'll be higher up the power curve when you engage the next gear. Thrash the nuts off it.

This is true, yet to see an engine this isn't the case with - even turbo engines with the boost dropping off at the end of the rev range. Look at any power graph to see for yourself. You'd need very, very close gears for this not to be the case - it's nearly impossible.

 

Don't hold it on the rev limit for long as said though if you want to test for yourself.

 

Dunc.

Edited October 29, 2009 by dunc

[Cloverleaf 1]

I have to agree, changing gear after peak power is quicker for the majority of engines. As said, it puts you higher up the curve in the next gear. However, avoid hitting the limiter as it's not good for the engine and will waste time. Change just before

[Rob Thomson 6]

Hitting the limiter is quite bad for an engine, so I wouldn't if I were you.

Hitting it briefly won't do any harm at all.

 

Well there perhaps is one answer to your question elsewhere about how you could improve your lap times Rob.

Certainly not with a revvy 1.6 GTi.

 

Behaviour like dan said, is quite different to an Mi or 8v, unless the cams are retarded slightly they don't scream all the way to the limiter, I have advanced my inlet cam so it dies off even more once past 6600 or so, but it pulls far stronger at 4-5k.

 

They die down very quickly after hitting peak power at around the 6.5k mark, so holding on to the gear for another 900 rpm or so is rather pointless, change gear at 6500 and you'll make far quicker progress.

I've only driven a GTi-6 once, but it seemed quite happy to buzz round to its limiter. Perhaps it was a good one?

 

Still, it takes an extremely aesthmatic (sp?) normally aspirated petrol engine to not develop it's peak through-the-gears performance when revved to (near) its limiter. Less than peak torque in a low gear is almost always better than peak torque in a high gear, unless you have a very odd power/torque curve (ie. forced induction).

 

Incidentally, why would Peugeot set such a high rev limit if there wasn't a performance benefit?

[Cameron 16]

Weeeeel, actually weather you should wind it round to the limiter or not depends on your gear ratios, particularly the rev drops in each gear and how that coincides with the power curve. An engine that makes it's peak power at the limiter will benefit holding onto each gear for longer. But with an engine that has peak power at say 6K and revs to 7K you may well find that it isn't worth holding out for the rev limit, as your gearing will drop you to an area of equal power at fewer revs, but the crucial difference will be that you are just coming on power rather than off it.

 

We have a very good ratio calculator at uni, that compares in gear torques versus power curve and gear speed (amongst other things). I'll be sticking my ratios into it to find ideal gearchange revs and I'll be quite surprised if it turns out to be on the limiter in every gear.

Edited October 29, 2009 by Cameron

[Cameron 16]

Hitting it briefly won't do any harm at all.

 

Hitting it briefly repeatedly will.

[taylorspug 7]

Hitting it briefly repeatedly will.

 

Mine must be knackered then...its been doing it for a year and a half.

 

Or not as it made the best part of 190hp a few weeks ago!

 

Ive retarded the inlet on mine, so it makes power right up to the limiter, and then drops nicely back into the power band on gearchange. Granted its got throttle bodies on but even before this it was the quickest '6 engined 205 id driven (and thats a fair few now).

Edited October 29, 2009 by taylorspug

[Batfink 201]

Erm is the limiter not there for a reason - to protect the engine from overreving. Whats a standard rev limiter?soft cutout? Wont it just retard the ignition to drop the power. Obviously higher revs means more wear....

[jackherer 543]

I don't know about the GTI6 but an Mi16 will happily sit on the rev limiter in fifth (1.6 box) for quite a while without causing any harm...

 

As Batfink mentions, I think its a soft cut which retards the ignition until revs drop below the limit then advances again in a continuous cycle. A fuel cut limiter might cause problems I suppose.

[Cameron 16]

Its more the bouncing back and forth on the engine mounts that's bad for it, have you ever looked at an engine when it hits the limiter? Especially on standard mounts, they go bezerk!

 

Anyway, my opinion is that its bad to bounce it off the limiter. You lot can carry on!

[Anthony 1,003]

Its more the bouncing back and forth on the engine mounts that's bad for it, have you ever looked at an engine when it hits the limiter? Especially on standard mounts, they go bezerk!

Won't do the engine itself any harm though, will it?

[Cameron 16]

Certainly isn't going to do anything good for it..

I'm not talking about hitting the limiter in 5th here, I'm talking about 1st and second where the force is far far greater and the frequency higher.

 

Anyway.. Seems we aren't going to get anywhere until you lot hear this this so..

 

I'm wrong.

 

Can we move this along now?

Edited October 29, 2009 by Cameron

[Batfink 201]

OK lol

 

its pretty stupid to hit the revlimiter in 1st and 2nd

i'm intrigued now to watch an engine hit the limiter for a while on a dyno run then as thats about the only time the bonnet is up. I never thought about the engine mounts. Wonder what happens when the engine is sold mounted...

Edited October 29, 2009 by Batfink

[Cameron 16]

Well I was thinking more about what's happening inside the engine.. sudden loading of the bearings due to the on / off power can't be good for them. The rev limiter is there purely to stop damaging the engine by over-revving it, but that doesn't mean that no damage can be done by the limiter itself.

 

If you want to get really into it, even if the rev limiter doesn't hurt the engine, it wastes precious time. If you're waiting for the limiter, by the time you've hit it and reacted by changing gear you've wasted an amount of time equivalent to your reaction time. Ideally, you would pre-empt the limiter and change gear 1rpm before you hit it.

Edited October 29, 2009 by Cameron

[Rob Thomson 6]

I'll be quite surprised if it turns out to be on the limiter in every gear.

I'll be surprised if it doesn't!

 

Hitting it briefly repeatedly will.

I'd be very surprised if the additional wear is significant. I'm mechanically sympathetic in how I drive, with the one exception of revving engines to, or near to, maximum revs when pressing on. None of my cars have ever shown any ill effects despite being thrashed relentlessly. Be that the 205, my old 106 Rallye, or the Mondeo. They've all hit the limiter many times with zero effect.

 

Obviously higher revs means more wear....

Yep, which is why a manufacturer would set the limiter lower if there wasn't any benefit to be had from the higher revs. Wear and stresses increase exponentially with high revs, so why permit them?

 

If you want to get really into it, even if the rev limiter doesn't hurt the engine, it wastes precious time. If you're waiting for the limiter, by the time you've hit it and reacted by changing gear you've wasted an amount of time equivalent to your reaction time. Ideally, you would pre-empt the limiter and change gear 1rpm before you hit it.

Obviously. But you need to hit it once to know where it is.

[Cameron 16]

Well, since my engine makes peak power very close to the rev limit I'd guess that it would be better to rev to 7.25K, but the ratios are a compromise naturally, being OEM designed, they aren't specified with perfect rev-drops in mind. I won't be accepting anything as right or wrong until I've seen it for myself, assumption being the mother of all f***-ups.

 

I'm not saying that your engine will shatter into a bunch of cogs and springs if you touch the limiter in each gear, but I can imagine what's going on in there while you do, so I stay off it.

[CaptainK 11]

I have a GTi6 in mine (now with throttle bodies). When it was standard I found driving it up to around 6500-6800ishrpm was the best performance way of driving it. Anything after that and it just seem to slow down. Obviously it isn't as its still accelerating, but it didn't feel as quick. Quick gearchange and off she goes again.

 

Now its on the ITBs, fully mapped and Catcams set up correctly its a different monster and just keeps going until my new shift light scares me into changing gear.

[Cameron 16]

That's what I was saying, after peak power the power starts to fall away, and torque falls rapidly. So depending on your gear ratios it may well be better to short shift as you would drop nicely to an RPM where you're making as much power, but more torque!

Edited October 30, 2009 by Cameron