Race Engine Forum UK

Hi. I'm currently tuning my Fiat Coupe 16VT and I'd like to know what rpm I can raise the rev limiter to with regards to mechanical failure.

I'll try to relay as many relevant details as possible:

Stock valvetrain
400 bhp / 289 lbf ft
Original valve springs from 1996
Fiat Tipo inlet cam / Coupe 16VT inlet cam (on exhaust!)
Wossner forged pistons (84.6mm dia.)
"PEC" branded steel H-beam conrods (2 grammes weight difference between them)
lightened + balanced flywheel (don't know what weight)
stock crank

Aw, nobody? :(

To any Fiat Lancia 16V Turbo owners What rev limits are you running and why? What's your engine spec?

Hello Kj,

Assuming you can make it breathe far enough to break something mechanically . Has the head been ported or standard ?

The valve springs could well be the limiting factor being as the std engine revs to what 6000 rpm ? Lancia didn't intend those springs to go much further, not just in terms of valve float but also factors to do with pressures across the engine. I think the weakest link in the chain concerning the short part of the engine could well be the piston coming off the rod. Not heard of your rods before but I think a rod can go at anytime anyway ie; not altogether rpm dependant.

I wouldn't like to put a number on it and say "yes, that will be ok . I guess the right way to find out is on a dyno and see where the power stops climbing or you start to see diminishing returns.

Hi. Tricky

My engine makes peak power at 6200 rpm and still makes useful power at 7000 rpm. The stock limiter on the Coupe is 7000 rpm. Normally adequate, but with 400 bhp it can hit the limiter very quickly! So the intention to raise the limit is just for "driveability"as opposed to making power, if you see what I mean.

Hi KJ

I would suggest you need to think about gear ratios / final drive / larger rolling wheel diameter, to make use of your improved torque.
That's where the driveability you're seeking lies, not in gaining a couple of hundred rpm at the top end. (& thus a few more mph)

Space the gear changes out so that when you reach 7000rpm you're already traveling faster as you change up.

Its all a compromise somewhere - what are you looking for - increased top speed, or getting to your gear limited Vmax as quickly as possible (which you are already doing) ?

Rgds
Matt

I know theres a tread here somewere on rev limit on the original flywheel wich i think is your limiting factor around 7200-7500 A lightend flywheel and a balanced bottom end would cover you for 8000 i think. Dont shoot me if im wrong though :)

lol, I shouldn't have used the word driveability! What you're saying, MattD is correct, but I'm not after top speed or vmax. These, as you said, are functions of gearing.

The reasons why I want to raise the rev limit are:
1. to make use of the power the engine now makes at high revs
2. to decrease the likelihood of bouncing off the limiter in 1st 2nd and 3rd!
These are the only two reasons you should want to raise a rev limit for!

berjohansen: Thanks I'll search the forum.

With stock valve springs safe limit 7500 really although I have seen them go higher. The float limit is higher than the 8v as the valves are lighter.

GC

Hi guy. Is that all original including flywheel?

yes you won't have any problems with any part of the engine at that speed.

G