Valves floating at 7500 rpm??

[bjerre]

Hi Im Martin from Denmark, sorry my bad english
have eny of you experied this?
I have just damaged with my Clio engine, which have going well for 2 years. but the other day it was on the dyno and we raised the rev limiter from 7200 to 7500, not much I think but after some normal driving without problems sudentlig at hi rpm the engine stoped with bad noises. it seem that the valves is floating at hi rpm and they dont get closed quick enough before the piston goes in top, so I damaged the head, valves, pistons and the cylinder block.
The timing belt timing was ok and I have fixed the belt gears with a not. so this is not the problem.
but only 300 rpm more than standard?? is this enough to make the walves floating.??
Have enyone tried to use harder springs or dubbel springs then the one catcams sell?? Maybe if they are too hard to press the hydraulik lifters can not do it?

Have someone tried to build the hyd lifters to mechanical??
ore have another sugestion.

If this helps Engine data:
fixed crank puller
Catcams 292/284
Catcams valves springs
fixed Catcams adjust. camgears
Catcams conrods
Renault Sport forged pistons
4 endividual throthle bodies
homemade 4-2-1 exhaust manifold.
225 hp at 7258 rpm
240 nm at 5516 rpm

 

[Fred@BTM]

what do you mean by "fixed crank puller"

my friend is Danish and is good with clios, i can give you his phone number and you can explain to him your problems, then he can call me and translate if that is easier for you?

 

[sideways danny]

I "think" this sounds like a valve head failure. Fairly well known problem if it is that. I dont think the F4R likes holding high revs as it seems to be when they're over revved that the valves break

 

[Fred@BTM]

luck of the draw danny, i know engines with 100K on them that have had R-sport ecus for 75% of that milage with an 8k rev limiter, i also know of one engine with 30k that had dropped a valve head

camcams 423's with adjustable pulleys? correct?

 

[drhowser]

what do you mean by "fixed crank puller"

vvt removal maybe?

 

[Fred@BTM]

no i think he means "fixed crank pulley" as in he has keyed it

 

[drhowser]

the crank bit gives it away i suppose

i'm not very alert at the moment.....

 

[sideways danny]

luck of the draw danny, i know engines with 100K on them that have had R-sport ecus for 75% of that milage with an 8k rev limiter, i also know of one engine with 30k that had dropped a valve head

camcams 423's with adjustable pulleys? correct?

yeah dont mean the fact they're hitting high revs, but more they're bounced off the limiter for far too long

 

[Barron]

225hp, was that at the wheels or at the fly? :O

 

[Andrew Cooke]

no i think he means "fixed crank pulley" as in he has keyed it

maybe, or maybe he has one without the damper?

 

[bjerre]

the 225 hp and 240 nm is at the fly.
yes 423 with adjustable gears
yes the vvt is removed.
I dont know exatly how I explain the fixed cam/crank gears but original the gears are only hold in posision by the tighten bolt but we have cut out keyway and mount. af key. so this is not the problem. we have measured when we assamblied the engine that there was clearence between piston and walves in TDC.
but now I can see markes from all valves in all piston.
so I think the valves can not close fast enougt.
It just seems strange when we only rew 7500 rpm.

 

[bjerre]

have someone experience with harder or dubbel valve springs or have any sugest.
www.bjerre-rally.dk

 

[Fred@BTM]

why did you bother doing that to the crank?? no need

 

[bjerre]

well when we started racing in the Clio we heard that it should be a problem for ClioCup cirquit racing that the crank gear would ran lose. so thats why we did it just to be sure. we use the Clio for rally and do af lot of hard up and down shift. we drive with the sadev 6 speed sekvensiel gearbox.
we dont have so much experience with renault. only with Toyota and there are everything keyed

 

[Fred@BTM]

no need at all to key it

 

[GodSpeed]

well when we started racing in the Clio we heard that it should be a problem for ClioCup cirquit racing that the crank gear would ran lose. so thats why we did it just to be sure. we use the Clio for rally and do af lot of hard up and down shift. we drive with the sadev 6 speed sekvensiel gearbox.
we dont have so much experience with renault. only with Toyota and there are everything keyed

If you buy a new crank pully from Renault they are now all keyed so there may be some kind of truth to it.

Previously discused from post #16 in this thread: http://www.cliosport.net/forum/showthread.php?t=482783

 

[Fred@BTM]

^the key is removable

no truth to it at all

 

[GodSpeed]

^the key is removable

no truth to it at all

I did not dare to remove it tbh. Thought what if the new one doesn’t have the same "pinching" force on to the crank as the old one, it does not have to stay in place because of the key. Not likely I know but as some smart person wrote: "Assumption is the mother of all f**kups"

Logics = Renault must have made the change for a reason.

 

[Fred@BTM]

they never changed it it turns out, its the same pulley with a key pressed in, it just pings out with a screw driver!!!

so renault designed the 172/182 WITHOUT a key for a reason

 

[GodSpeed]

they never changed it it turns out, its the same pulley with a key pressed in, it just pings out with a screw driver!!!

so renault designed the 172/182 WITHOUT a key for a reason

That was news I must say, no kind of description of this procedure comes with the pulley. Nice one Renault.... *sigh*

 

[bjerre]

In the danish ClioCup it should be a big problem that the crank timing belt gear are going loose but for street use maybe it is not af problem, so to be sure we keyed it.

 

[Fred@BTM]

^never a problem in the uk, maybe whoever looks after the engines in denmark was, erm s**t?

if the bolt comes loose it won't matter if its keyed or not, ifs going to be fucked either way!

 

[sideways danny]

^never a problem in the uk, maybe whoever looks after the engines in denmark was, erm s**t?

if the bolt comes loose it won't matter if its keyed or not, ifs going to be f**ked either way!

yup. I've seen a few engines where the crank bolt has come loose, and it' just ruins the key, the keyway, the pulleys and generally the whole engine

 

[Fred@BTM]

loctite do some stuff that might help

 

[sideways danny]

one of them had the crank bolt crossed. How you cross an M18 bolt is beyond me

 

[Fred@BTM]

airgun + close eyes + scream like a girl = possible

 

[Terry172]

As it's related to this thread I just wanted to know why 7500 would be a problem as I have read so much about people raising their limiters to 7800 etc?

airgun + close eyes + scream like a girl = possible

PMSL at picturing this scenario

 

[Fred@BTM]

we ran 7500 (with a stock crank pulley setup) cira 240bhp F4R

didn't need anymore revs!