still getting top end cut out (death)
Turbo Mini Forums

Second Nic, on the valve guides, ive had this problem with 3 different heads on turbo motors using bronze guides, my car is still doing it at the minute with a new head, be careful as you could drop a valve or bend it as the valve sticks and the piston can clip the valve, i solved it before by taking the head off and running more clearance in the exhaust guide.

i had this problem & it was leaning out what needle you useing? & what boost? ive got a bca reprofiled to get fueling right for around 13-15psi & if iam right in thinking the bca is richer than the bdd when both in std form so you might have to start with a richer needle to begin with (have you not just had this set on the rr?)

On 26th Nov, 2011 eden7842 said:
theres never any smoke, and its one of your heads benross.

from what everyone's saying i think it must be fuel, how do i go about richening top end even tho my needle is like a pin?


Nobody has stated anything to do with the needle or richening the top end.

You need fuel to the carburettor !!


my car is a little lean top end,

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

i do have bronze guides, its a benross fast road head ''i think'' do people have this problem with these?

how do i confirm this?

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

I think MR Riz may be onto something thinking about it. If it has only happend since fitting the new head.

Nic did you find it made a difference when the engine was cold and up to full temp? Could be an easy way to confirm if it doesn't do it from cold?

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1/4mile in 13.2sec @ 111 terminal on 15psi

matty you thinking i start it up thrash is down the bypass (cold) and see if it does it?

the head is starting to look like the probable cause

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

It will still happen when cold I think. It just may take a longer full throttle run to happen. I seem to recall this happening when I thought I had fixed it but hadn't.

Looking at what people have said, you're best off whipping the head off, dismantling it and checking the valves, I'd have thought you'd have wear marks if the guides have been 'pinching' them. And then ream the guides out ever so slightly more as others have done just to make sure.

valve stem seals on all 8 valves?

Yes i moved to the darkside

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If you have changed the head for one with more porting and large valves and not had it on the rollers again, chances are it will need more fuel at the top end...

The head spec was less ported than my old 1 just better valves and guides.

I think im going to whip the head off and have a look at the exhaust valves + guides and probibly slacken them off a tad

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

eden i always ream the valve guides, when they have been pressed in,

any missfires under boost is usally caused by mixture too lean

i have not had any problems with the valves nipping up with other heads..... but if your judgement is pointing you in that direction then by all means pop a 9/32 reamer through the guides, to possibley eliminate this............ if you have any problems at all please pm me.

But the symptoms as described do not sound like a head issue anyway !

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

I don't think it sounds like the head either stevie.

I'd be looking at the pump and any restrictions to the carb first.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

The pump is 1 year old bosch. With new pipework and filter. And the carb has been checked,

But to me if it was a fuel issue it wuld lean rite out on the afr?

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

not necasaraly,

if the reg/pump/ fuel feed is playing up you still have a float chamber (or part of one) of fuel to burn, then it'll fuck about.

wenever ive had fuel supply issues its just cut out on boost?

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

T PEICE trick eden ? have you implimented that

its got the T piece in, was the 1st thing i tried

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

sorry i ment 13.2 not 3

ive gave the best description that i can, obv the best thing would be for someone to come out in it with me for a second view on things.

ive experienced fuel issues before and that would lead to the car cutting out, where this problem makes the engine go, or close to idle, but wont pick up for a few seconds.

which would make sense with the guides as they would need those seconds to recover

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

is 13.2 not lean tho on wot? iam looking at low 11s high 10 afr on flat out

So.

Still no answer to fuel pressure.
Still no answer to does it do this when static.
Still no answer does it do it if you gently go to high rpm
Still no answer does it do it at various boost pressures.

When you say 13.2 AFR, when is this ? You dont give any info. if at full load, this is too lean and risks damage.

Again, the more sensible information you give, the more chance of getting help.

The only valve guide related problems I ever had, the first head the valves ripped the sleeves inserted for offset guides from the head.
These were then grub screwed into place...they then ripped the guides from the head.
He did yet another head, and whilst the guides did stay in place, the engine nearly always hit a brick wall around 6500rpm in 4th, slightly higher in 3rd.
Although it was more like a rev limiter in my case. Nothing whatsoever like what you describe.

I never did figure out why. I changed back to my old head which was badly cracked, and it ran perfect. I then had a head done by Swiftune, and it too was perfect, 7500rpm in every gear no problem at all.
It's still on the car today...well, what is left that hasnt rusted away of the car lol

So certainly a cylinder head done badly can cause weird problems, but not like the symptoms you are vaguely describing.

I will add that the shoddy head I got years ago was not done by Benross just in case it reads that way. Mine was way back around 1995.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

yes it is lean, i was aiming for around 12.7ish but couldn't get it there. but (ashamed, head down) ive ran leaner in my old lump with no such issues?

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

If its wa me I'd.

1. back the boost right off and see if the problem gets better..if it doesn't..

2. Keep it on low boost and try and get to top revs using part thottle...see if it cuts out still...if so..

3. The other thing ive tried in the past, is running a peice of clear tubing between the FPR and carb and poke it out of the back of the bonnet. Drive along and keep an eye on the tube, if you see air locks in the tube just before or during it cuts out, its got to be fuel starvation.

Edited by matty on 28th Nov, 2011.

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1/4mile in 13.2sec @ 111 terminal on 15psi