Small Problem at Sandown Raceway

**jimnielsen** · 18-01-09, 08:12

well, A big problem really, As you can see and hear in the attached video at 3:15 seconds in - the car loses most of its power. A quick check found that the spark plug electrode in #3 had melted (presumably due to detonation). In the video you can see that boost is well controlled at approx 1.05 bar during the previous two laps but suddenly it spikes to 1.3 bar and stays there. From the sound of the engine this is as a consequence of the problem - not the cause of it. I have checked the timing and the cam belt tooth positioning - they are still fine - but I have not had time to do a compression test yet. Will do one tomorrow.....

video...

[ame="http://au.youtube.com/watch?v=Q6DPSQPoOUU"]YouTube - sandown09[/ame]

**wrinx** · 18-01-09, 11:27

Bugger

Is this with your new turbo?

Odd that it suddenly spiked to 1.3, does your map allow for enough fuel at that boost? Perhaps that melted the plug?

...and what's that annoying squeak?

wrinx

**jimnielsen** · 18-01-09, 19:36

No, it still has the standard turbo. The 'squeak' is the metal on metal of the rear harness mountings. I think that the problem happened before the car went to 1.3 bar boost. Normally, the car cannot make that level of boost at those revs. it seems to me that something about the failure mode caused the extra boost to show up, but was not the cause of the failure. I could be wrong. I am going to give it a compression and leak down test this morning.

jimn~

**jimnielsen** · 18-01-09, 23:40

I have searched the site, and cannot find an answer to this question -

what are the typical compression test values found in a healthy Q4 engine?

Thanks - jimn~

**cuore_sportivo_155** · 18-01-09, 23:40

how rich are you running? going slightly richer reduces the chance for detonation... maybe one injector isn't delivering quite what it should?

**cuore_sportivo_155** · 18-01-09, 23:42

Originally Posted by jimnielsen

I have searched the site, and cannot find an answer to this question -

what are the typical compression test values found in a healthy Q4 engine?

Thanks - jimn~

can't say, depends on the cams, timing and valve play. make sure all cilinders are producing the same pressure, that's most important...

**jimnielsen** · 19-01-09, 02:01

Compression Test results..

1 # 172 psi
2 # 158
3 # 0
4 # 131

Also did a leak down test, which showed 1 & 2 to be ok, 4 very marginal and 3 total failure. I suspect a failed head gasket between 3&4.

fuel ratio is approx 11.5:1 at WOT. I will test the injectors before I put it back together.

**jimnielsen** · 19-01-09, 05:32

I have made a little progress.... Should have the head off tomorrow (if all goes according to plan..) When I drained the radiator, I noticed that it was very dirty, and obviously very contaminated by combustion gases. It had been clean at the start of the run - so another pointer towards a failed head gasket.

I have taken the turbo off as I'm planning on implementing a different one at the same time a s fixing this current "issue" - easier to do that with the radiator out, that I need to flush anyway!

Any suggestions on what sort of head gasket to go with - or should I just use a 'standard' Alfa one?

cheers, Jimn~

**wrinx** · 19-01-09, 07:24

Spesso are supposed to be very good

...and as you drive the car more or less as a race car, I'd be wanting an uprated gasket.

wrinx

**Evodelta** · 19-01-09, 10:52

Cometic are the best ones to have, as Wrinks says, Spesso are also good.

**cuore_sportivo_155** · 19-01-09, 16:51

get an extra thick one, to reduce compression a bit, and see if there's a need or chance to unschroud the valves on the intake.... this will increase flow and reduce the CR a bit more, allowing for more boost without detonation

BTW, what about your knock sensor?

**Stuntz** · 19-01-09, 18:13

Hi jim! Im very glad to se you changed you driveing style a bit.

1.3 bar was probably caused by unburned fuel igniteing in the exhaust due to failed spark plug.

Greets Klemen

**mindus** · 19-01-09, 22:51

Also, I would change head bolts to a larger diameter ones if you are going for uprated headgasket. The head lifts under high boost since the bolts can not hold it in place.

Spesso headgasket with separate rings (group A) can handle loads of torque, and also NOS if you are up for drag racing

And you need less skills (and not so perfect head surface) to install spesso than cometic

**jimnielsen** · 20-01-09, 09:02

I almost had that head off today - until I discovered that the bolts are of the Ribe/polydrive sort. They are very uncommon here. I have Torx type drives but they don't quite fit. Hopefully I can get something tomorrow.

I am going to put 12mm bolts in it before I reassemble the engine. Has anybody tried using 12mm studs instead of bolts - that would make it easier and cheaper. ARP has a good range.

I am planning on using a copper head gasket with ORings in the cylinder liners.

jimn.

**na15575** · 20-01-09, 09:31

Originally Posted by Stuntz

Hi jim! Im very glad to se you changed you driveing style a bit.

1.3 bar was probably caused by unburned fuel igniteing in the exhaust due to failed spark plug.

Greets Klemen

i agree with Klemen

i have use 12mm bolts
and a spesso headgasket with separate rings (group A)
from here
http://www.walkers-garage.co.uk/shop/

**jimnielsen** · 20-01-09, 10:36

did you pull out the block to have the M12 holes drilled or was it done with the block still in the car?

:0 cheers - jimn~

**arjunior45** · 21-01-09, 16:33

Originally Posted by jimnielsen

I almost had that head off today - until I discovered that the bolts are of the Ribe/polydrive sort. They are very uncommon here. I have Torx type drives but they don't quite fit. Hopefully I can get something tomorrow.

I am going to put 12mm bolts in it before I reassemble the engine. Has anybody tried using 12mm studs instead of bolts - that would make it easier and cheaper. ARP has a good range.

I am planning on using a copper head gasket with ORings in the cylinder liners.

jimn.

I'm going to use 12mm studs {instead of the bolds} as, in my opinion, does not deform {length increase} that much as the bolds. Go for them.

Nick

PS.
Could you please measure the exact length of the oem bolds?

**jimnielsen** · 21-01-09, 19:52

yes, i'll measure the original ones for you as soon as I get out out!

jimn~

**na15575** · 22-01-09, 07:55

Originally Posted by jimnielsen

did you pull out the block to have the M12 holes drilled or was it done with the block still in the car?

:0 cheers - jimn~

yes the block was out of the car?
if i was you
im going to pull out the engine and make it from the begin
forget pistons bored,drilled and all this

**1NRO** · 22-01-09, 15:33

Hello everyone on Berlina Sportivo. Whilst this isn't quite my first post I'm obviously new and an introduction is in order. My name is Nik Osborne and I reside in the tax sucking contry that is the UK, up north in Carlisle. I have a selection of parts for your interest

Both head and main studs. The head studs are 12mm.

These are made by a company that makes the fasteners for almost all the F1 teams, from the same material as they use until very recently. The level of quality can't be beaten and the design is not at all random. They feature rolled threads and a proper seating detail. The main studs have a pip on them locate the main caps perfectly and a girdle that fits over them to make sure all is as perfect as can be.
The studs are available for purchase from me. They come with ARP nuts and washers. The head studs cost ?250. Not cheap I know but quality never is and I work on a very small margin, there's no ripping folk off. From a personal point of view I'm an avarage Joe and know what it is to watch the pennies, I will spend the money in the right areas though.

Nik

**jimnielsen** · 23-01-09, 00:50

Well, after a long battle to get an M12 Ribe bit to remove the head bolts, mine finally arrived - so after a few minutes the nature of the problem has become more apparent...

**jimnielsen** · 23-01-09, 00:52

Just a couple more photos...

**Evodelta** · 23-01-09, 06:39

Now there's classic detonation if ever I saw it.

**wrinx** · 23-01-09, 08:46

Owww, not good

Certainly matches the description here:
http://www.streetrodstuff.com/Articl...ion/Page_2.php

Hope the fix is not to expensive...or is it time for forged pistons???

wrinx

**arjunior45** · 23-01-09, 08:53

quite a lot of mess!!! sorry to see that Jim.

What do you think is the reason for all that?

Hope to see this car buck on the tracks soon.

Regards

Nick

PS.
Thats the kind of stud {mentioned by 1NRO} I meant