Wheres my missing ponys?

[Alexdaredevilz]

I've checked the timing 12 degrees idle, 36 advance with vac 28 with vac hose off 4000 rpm
Compression test, most were 180-210 psi
Checked the fuel pressure
Checked the fuelling (little rich 12.2:1)
Checked throttle pot
Cats cant be blocked as there is non(blocked silencer?)
Spark plugs renewed and checked
Renewed fuel filter
Checked AFM
And probably a few more things I cant remember off the top of my head

What's left to check?

I know my car revs OK, as I recently saw it at 6700rpm on a dyno
Idles ok
Starts ok

Is there some thing staring at me in the face that's not right ive missed?

The prize to pin point this problem will be a 5 course meal with my self

Thanks

Alex

Edited by Alexdaredevilz on Tuesday 21st June 19:55

[MADMAX2]

try pressing the accelerator pedal harder

[carbon14]

Hi,
I went through a similar long list of checks looking for lost HPs, plus I also checked all sensors and feeds to ECU. At the end it was the valve guides that were not tight anymore. The car made only 240 HP on a serious rolling-road... it was basically sucking oil through the valve guide (previously it made 167HP with a completely worn cam (2 lobes were just circular)). So worth to check if your oil consumption is high. This was part 1 of the search for more HPs. Part 2 was a visit to V8D - and upgrade the heads, the whole intake and changed (again) the cam to a stealth cam. Now around 300HP with a very nice torque curve.
Cheers,
C14

[Alexdaredevilz]

Oil consumption isn't that bad, but does get through some especially at higher rpm,

The heads are already V8D

But are 11 years old and done about 50k

[Chimpafrolic]

Hi Alex, once the cam was out I measured the lift on each lobe and cross referenced with the figures from my on car method.

Turned out my on car method was more or less spot on.

Well, it was good enough to highlight the one dead lobe, the one on the way out & the others slightly but evenly worn.

So although the method I used wasn't very scientific and the hydraulic lifters can mask the exact lift figures I feel its still a useful way of getting a general picture of the cam wear without pulling the cam.

When I did my on car lift checks the same two lobes kept jumping out at me as being worn, I measured them over and over & it was always the same.

Sure enough with the cam out it was those same lobes that proved to be the problem ones.

Looking at my old cam off the car it certainly wasn't as bad as some of the horribly worn ones you see posted on here from time to time, but Rob did point out the followers were quite badly dished.

Interestingly I had spoken with a guy from Piper Cams at the Race Retro show just a week before the old cam came out, Piper man suggested the followers were often more of a problem on the RV8 than the cam itself.

Any how its all pretty academic really because once Rob had fitted the Stealth cam the difference was immediately obvious, the car felt much much stronger.

In fact it showed up another issue, my clutch was slipping!

So I now suspect my dismal power run last year was mostly down to a worn cam & a bit of slipping clutch when it got a good spanking on the rollers.

With any luck the Helix clutch and Rob's lightened flywheel will all be in place next week & I will toddle off to a rolling road to see what it does.

I think "Surrey Rolling Road" is closest to me, everyone seems to get 5-10bhp more and come out happy when they go there

If I am really lucky and with a strong tail wind perhaps it might even break the 200hp barrier this time

[JonathanT]

carbon14 said:

Hi,
At the end it was the valve guides that were not tight anymore. The car made only 240 HP on a serious rolling-road... it was basically sucking oil through the valve guide (previously it made 167HP with a completely worn cam (2 lobes were just circular)). So worth to check if your oil consumption is high.

hmmmm. the oil consumption is high-ish on mine (a litre every 500ish miles) with no evidence of leaking when it previously used very little. Is there any other way of telling if my valve guides are worn? and is there a relatively easy fix?

[Chimpafrolic]

JonathanT said:

hmmmm. the oil consumption is high-ish on mine (a litre every 500ish miles) with no evidence of leaking when it previously used very little. Is there any other way of telling if my valve guides are worn? and is there a relatively easy fix?

If your oil consumption is a little on the high side and you want to establish where the wear is you could try this:

• Stand at the back of the car & get someone to rev the engine to 2,500rpm (or more) and hold it there for a few seconds

• When you are ready, get your able assistant to lift off the throttle sharply

You are looking for blue smoke from the exhausts.

Lifting off the throttle sharply, momentarily creates a very strong vacuum in the inlet manifold.

The higher the revs before you lift off the higher the vacuum will be.

If the valve guides are badly worn this vacuum will draw oil down the guides into the inlet manifold.

The oil then gets drawn into the combustion chambers on the next induction stroke and burnt, this burnt oil eventually exits the exhaust as a volume of visibly blue smoke.

The general rule is:

• If it produces a bit of blue smoke all the time it's normally the piston rings

• If it only produces blue smoke on the over run it's normally the valve guides

If its smoking on the over run ,replacing the valve stem seals may help a bit but you really need new guides (& possibly valves) to sort it properly, and that's a full heads off & recondition job.

My advice would be to clean all your breather pipes out before doing any testing, blocked breathers can significantly contribute to excessive oil consumption.

If the breather pipes are even partially blocked it will use oil, but the rings & guides may still be perfectly serviceable.

So a good inspection & clean of the the breathers should always be your starting point.

When you are sure the all breather pipes are clear do the over run test above.

If your visual smoke tests are inconclusive you need to do a compression test.

This should be done with the fuel pump & 12v coil lead disconnected (you don't want the car to start when you are doing a compression test), make a note of your readings on each cylinder.

You are looking for any cylinder/s that are showing a lower figure than the others, cylinders rarely wear evenly, if you get good consistent figures across all cylinders its probably not the rings or bores that are worn. "This is known as a dry compression test"

Then with the fuel pump & coil still disconnected squirt a small quantity of oil down each bore, repeat the compression test and record the figures. "This is known as a wet compression test"

The general rule is:

• If it you see an improvement when you do the wet test its normally the piston rings, this is because your squirt of oil made a temporary seal where the rings are failing

• If the compression fugues don't vary much between the wet & dry test, your breathers are clear and its still using oil its normally the valve guides

Hope this helps?

[JonathanT]

Chimpafrolic said:

Hope this helps?

thanks for your very comprehensive list of things to try!

I presume I need to check both the breather/flame trap on the front of the driver side and the mushroom filter on the back of the passenger side?

Edited by JonathanT on Thursday 26th May 10:50

[Andy_mr2sc]

Hey Alex lets swap engines! Then you can say you have a great healthy 4l that is only a few hp down on yours. Slip a cam in it while we are swapping and you will have the same hp.
Then I can save you all those head aches of sorting your lump out!
All of this for no charge!

I'll go and dig out the engine hoist.......

ps. any joy on the work front?