Engine Issue #2 - No Power

[ukkid35]

Although I've not put the car on a dyno, I'm guessing it currently has about 280bhp. This is based on my seat of the pants feeling that it's no quicker than my 928 which has 200bhp/ton. In all fairness I've stuck to a self imposed 6k redline, but that is in part due to the fact that it seems to struggle by the time it reaches 6k.

My only theory currently is that the intake tubes are collapsing under full power, the reinforcing wires have long since disappeared, so the tubes are very weak. I've not done any throttle balancing which I'm sure would help, but there is so much power missing that I'm looking for a major cause. Any thoughts would be very welcome. I can post the adaptive maps if that would help.

For what it's worth, the cold compression numbers are 225-260, so nothing fundamentally wrong as far as I can tell.

[N4 FTW]

What condition is the exhaust in?

Do you still have cats?

An exhaust blockage or cats collapsing could leave it feeling breathless top end and rob big power. Also, when was the last time the valve shims were adjusted?

[Gazzab]

Cam timing? Throttle pots? Purple pipes? Cats/exhaust?

[vroom]

Agree with the Collapsed Cat?

I suffered from one of those and before the diagnosis I was really disappointed with the performance (my previous 4 lite Chim was quicker)!

Replaced the old ones with some good 2nd hand ones sourced via PH classified.

I nearly crashed the car on my first drive - the difference was staggering!

[Allandwf]

+1 , also had collapsed cat, though you could hear it rattle from time to time.

[robsco]

Valve clearances?

[ukkid35]

The cats look pretty open to me, there's a honeycomb inner that you can see right through, and it isn't even full width so it rattles around in the can. However I can see the value of a swap, decat pipes would be the easiest option.

The valve clearances were adjusted as part of the headgasket job, all intake valve gaps had closed up, most of the exhaust valve gaps were spot on.

[FarmyardPants]

If you run the car with bonnet open and briefly mash the throttle you might be able to see what the (once) purple pipes are doing

Edit clogged air filter will tend to make them collapse more

Edited by FarmyardPants on Thursday 3rd November 11:00

[leman600]

Valve clearances incorrect tend to affect low rev characteristics more than further up the range. The mention of head gaskets tends to lend weight to the cam timing theory.

[Byker28i]

Not a bad time of year to be keeping the revs down anyway.

Time for my annual - lets be careful out there folks - message.

Wet roads, slippery leaves. Already picked up 3 scooter riders in the last few days, lets not have any Cerbera incidents please.

[ridds]

My money is on cam timing.

Mine pulled an easy 350 bhp with collapsing purple hoses (early ones without wires inserts).

[bobbins]

Byker28i said:

NWet roads, slippery leaves. Already picked up 3 scooter riders in the last few days, lets not have any Cerbera incidents please.

With the front of the Cerb? Ouch.

Same as Ridds really - mine was RRd at 350+ prior to SIC and remap, when a couple of the purple pipes looked like they'd given up.