20vt high rpm engine?

Hi,
I'm rebuilding an engine for my 4x4 coop and have some questions about revving the engine

When we were mapping the car (450bhp FWD) we set the limiter to 7900, the camshaft was too "weak" for that rpm so we lowered to 7500.
As I have BW S200SX, this turbo have full boost around 5000rpm so I have power in range of 2500rpm (toooooo short)

Now I'm rebuilding an engine with 2.4 head. Dry sump fitted (so no problem with pressure on high rpms). Accralite 83mm pistons and Cunningham rods stays in from old setup.

What I want is cc8500rpm, maybe some more . Solid lifers conversion is no problem to do. Suppose Stilo 2.4 valve springs are too weak for 8500?

Engine will be fully balanced (without balance shaft)

What about other parts? Crank, block? How It's dealing with higher rpms?
What is the highest rpm that someone reach with 20v engine?

Thanks and cheers!
Josip

I believe that JohnS experimented with an 8,000rpm limiter.

I run 7,400 (I also run Cunningham and Accralite) and I know several others run higher than this.

I would think you'll need stronger valve springs to get to more than 8,000, or solid lifters to reach 8,500

Biggenz was running upto 8,250rpm not sure if he carried out any work in relation to this or not though. (500+ bhp)

I've been told the standard head setup is fine for around 8200rpm more than that you'll need upgrades

Yes Biggenz was the highest rpm I have ever taken a Coupe too at 8200rpm. This was his decision, because it was certainly unchartered territory, but there were no apparent issues.

I have been pushing Coupes to 7800rpm for the last 7 years, never had any problems on a balanced engine. We are lucky that the 20vt is a shorter stroke, piston speed/rod ratio is not a problem.

I was just comparing 2.0 and 2.4 valves and springs.
2.0 valves are 54g intake and 46g exhaust
2.4 valves are 61g intake and 52g exhaust

The 2.4 valves are cc14% heavier with same springs on 2.0 and 2.4
So, to reach safe 8000+rpm uprated valve springs are must to do

I've just emailed Cunnigham and Accralite about max rev on their components. To be safe about that

Anyone buy uprated valve springs? where? I read somewhere about triple springs?

Flea> I'm not expert in engines, but I think that 8500 with good valvetrain and solid lifters is not problem?

If your going to the big valve head it's worth going for uprated valves which can take the extra heat of a turbo engine.

I know people have used the standard valves but I'm not trusting them in mine.

limit is the mean piston speed... it should not exceed 20-22m/s ..so for the 2ltr 5 cyl engine the safe limit with proper components is wery high.. at 8500rpm it has something around 21m/s... and stock components at lower bhp levels could handle these rpm.. maybe NA engines with right valvetrain can work with such high rpm when they are only properly balanced (and maybe for to be safe + new rod bolts)

the problem is in the valvetrain...

Yes and as already mentioned by flea 8200rpm is what has been tested at so far with out moving onto solid lifters or triple valve springs etc but also theres only a handful of people running turbos which require a rev limit near or higher than that.

Most of use with gt28 and the gt30 frame turbos won't need anything more than 7400rpm because they run out of puff/ efficiency

This is probably not very conventional, but another option would be to increase the resistance to flow oil in the hydraulic valve train which could increase the RPM level at which you might incur valve issues.

The lifter below is that of the 2.4 Stilo, in the past we have welded the little hole shut and re-drilled it to a smaller size, but to be honest I don't know if it made a difference since we fitted upgraded valve springs etc..

What I would like to do is to weld the valve lifter seat in the lifter solid so that there is no more play, but still space for the oil to enter the top part of the valve lifter so that the lifter can be lubricated through the hole on the side.

Risk, starving the valve lifter of oil

Better solution might be to "slit open" or extend the oil supply hole in the cylinder head towards direction of movement of the lifter.
This has been done in high rpm Ferrari heads with hydraulic lifters as well. Then the oil has more time to change towards the lifter.
This I did with my head.
Juergen

People rev the 16vt to that on stock crank
(25,5m/s)
Stock S2000 revs 25,2

they could..crank is not in this case problem, rods and pistons are..

S2000 is different category.. this engine is engineered from beggining to rev so high..our 16V/VT not (pistons weghting 412g wit big compression heght + short heavy rods - 810g..)

Im talking about stock crank, stock pistons and rods are 7500 or thereabouts?
Valvesprings and flywheel aswell..

ask here if they cam make stronger springs

www.performancesprings.com.au/

they have made reinforced springs for engines that nobody sold