Increasing max rev limit safely.

[Leejay-b 1]

I have always liked high revving cars...

I noticed a while back the ecutek mapped cars used 7800 rpm for the new rev limit.

Now fensport use 7650 rpm, which is still good and they must have their reasons. Also American tuners do opt for higher limits but have seen some also go no higher than 7600 rpm. Because of this I would question long term reliability of going higher. Even 7800 rpm could be a risk or why would some tuners keep away.

Anyway I'm now questioning 7600 rpm as have heard fensport have done a car at this revs only in 1st, 2nd and 3rd gears. Is this showing that it's still not fully safe?

Apologies if this doesn't make sense, basically don't see the point of more revs if damage can occur!

 

Probably only fensport will know why!

[rob275 1817]

Fensport have probably done that on a car sporting some forced induction, which is for obvious reasons. 7800 on N/A Shouldn't be an issue, though it seems to flatten off on the top end anyway so realistically you aren't going to gain from it. 

[Varelco 211]

You'll get a few different answers tbh, saying that 7600RPM seems to be widely agreed upon as safe, in fact there are guys stateside testing upto 9000RPM with varied results. However on the standard car the power tails off over 7k RPM so not sure what benefit you are looking for. IMO there is no point in raising the rev limiter for the sake of liking RPM. 

[Ade 517]

To get an FA20 revving to 9k it needs extensive work. Not just to actually get it to produce useable torque at those revs, but also to prevent something breaking.

[smudge 1020]

Anything over 7k is nearly pointless. No real power gain to be had from tests on the American forums

[Church 209]

I guess most don't go for higher rpm-s because 1) there is no more power on the plate at higher rpms on this engine, rather contrary, 2) higher rpms require more expensive and intrusive upgrades to engine vs simple bolton intake/exhaust upgrades including forced induction. It's not that often that one absolutely must on particular track due gearing have higher redline to cut down a bit laptimes, so maybe you shouldn't waste too much time/think too much of details of how much higher vs stock, or is it safe, as average driving both when daily driving and on track rarely sees reaching redline. Imho most wished gains should come in middle rpm range, as most commonly ran at, and also at which one shouldn't care about safety of too high rpms.

[Leejay-b 1]

Thanks for the responses.

If the FA20 is tailing off over 7600 rpm then I can see now there isnt much point, whether safe or not. Doesn't feel nice when an engine starts to tail off top end anyway, especially not a revvy N/A engine.

Only slight gain would be bringing you into higher revs for the next gear.

I think 7600 rpm max would be useful enough, added flexibility and means you can aim to get the revs up to 7250-7500 without hitting the limiter which is not good anyway.

 

[Leejay-b 1]

A post from an owner of a fensport mapped car on pistonheads- - -

'Power starts to flatten out just after 7650 rpm onto 7800 rpm after which it starts to drop.'

Their limit was set at 7650 rpm.

Maybe the standard car loses out after 7000 rpm, and the mapping unlocked some power 7000 - 7600 rpm. 

[Kodename47 446]

Maybe the standard car loses out after 7000 rpm, and the mapping unlocked some power 7000 - 7600 rpm. 

The standard car peaks at 6800, you can get it a little higher but not over 7k. It's due to the intake setup.

[JamesP1991 222]

My peak power now I am turbo is 7150rpm. For N/A I think intake work and valvetrain mods will need to be made to get it making power as the RPM increases closer to 8k. 

7K generally seems to be the sweet spot though with a stock engine. 

[Leejay-b 1]

I wouldn't be going far with N/A engine mods anyway... Seen dynos showing drops after 7000 rpm as suggested. 

So no real gain, think I may lift the limit to 7500 rpm or so, just so there is less chance of hitting limiter when going for max revs to try and get above 5000 rpm in the next gear!

[Sonic 4]

I think the main issue is the stock valve springs are pretty soft so I wouldn't be going past 7600rpm until these were replaced

[Mark@Abbey M/S 235]

stock GT86 max power at 6800rpm;

That's why we set the rev limiter to around 7300 rpm.

Issue with revving these motors harder;

 

1, valve spring specification;

2, crankcase issue with oil being churned around at high revs (engine breathing)

3, engine componets

4, piston speeds

 

 

 

 

 

[Leejay-b 1]

Cheers for the dyno and explanation.

Interesting to get info from a tuner with experience of the potential weak spots, better safe than sorry. 

 

[Leejay-b 1]

I have gone full circle...

Originally I was intending high revs for this engine at 7800 rpm.

After early responses I reduced my aim to 7600 rpm.

NOW just going safe with standard 7400 rpm at most. Later responses concerning peak power, and notes of risks to engine, so decided to go back to where the car is standard. 

Some minor extra revs won't affect the N/A character or peaky fun so I don't mind. 

[Sonic 4]

you could use the gear dependent rev limit in ECUtek so have 7600 in 1st & 2nd and then tail it off for the taller gears, as its only very briefly seeing the high rpm in the lower gears

[Tim Radley 18]

I've been running mine to 7800rpm for the last 1500 miles.  I did uprate the valve springs though when I blueprinted the engine but pistons and rods are stock and it's just fine at that.