Head job

The previous engine damage was not fixed. The car was lacking power, and another compression test still gave low figures on the middle two cylinders. Since the bottom end is fixed for sure, that leaves the valves.

Damaged intake valve. Caused by
excessive heat?

I just had the engine disassembled, why didn't I examine the head more thoroughly? Stupid!

Anyway, head off. With the engine still in the car it took just a couple of hours to get it apart. It is funny how much easier things are when you've done it before. Separating the head from the engine was for me something unthinkable not long ago.

A water test confirmed that the middle two cylinder's valves was leaking. So, time to disassemble the head as well. That is a bit more time consuming but not very hard, and can be done inside at the kitchen table :-)

- Do you have to keep the engine in the kitchen?
- It is just the head, dear.
- Ah, ok then.

Almost all of the valves on the middle two cylinders was damaged, both on the intake and exhaust side. Fortunately all of the valve seats looks as new. The pitting on a couple of the valves looked like it could have been caused by a foreign object. But if that was the case wouldn't it be dents in the seats as well? No, I still believe in the fuel starvation theory.

Seven new valves. Some lapping compound and the valves sealed again.

Here is a really good YouTube video of how to make a basic valve job.

Piston-to-valve clearance check

Before I put the head back to engine I decided to do a piston-to-valve clearance test using modelling clay. It is a very tediously process where you put some clay in the cylinder, and then mount the head, cams and timing chain back together and then turn the engine two turns and disassemble it again. To my surprise the clearance was about half of the Cosworth recommended 1.00mm!

Damn! Now what? I just want my engine back!

After a bit of grumble I decided to do the test again, this time being extra super careful with the cam timing. And the clearance was back. Now I know how sensitive it is. Under no circumstances the exhaust cam should be retarded. In fact, one or two degrees advanced exhaust timing is not wrong to be on the safe side. The same goes for the intake cam, but the other way around. I don't believe it was this sensitive with the old engine block.

Lash

"Lash" is the distance between the underside of the cam lobe and cam follower and is checked using feeler gauges. Because of the new valves I was required order four new cam followers from Burton. DHL is the best. They're the only freight company where my experiences has been positive most of the times.

First start today and first test drive this tonight. Always hard to tell if all the power was back or not, especially when it is dark outside, but the engine felt good and a new compression test gave the same results on all the cylinders.

Yay!

Engine rebuilt

I spent the first part of my summer vacation to rebuild the damaged engine. 

New block and new pistons, and a new built loom.

Started without troubles, but I forgot to turn on the video recorder!

A couple of test runs without issues. Ahh I've missed this!

My family is a bit tired on me working on the engine but now I can take a real vacation and enjoy the short summer.

Meanwhile - read Croc's article Getting decent video audio on your Seven.

New engine block

New Cosworth pistons.
I reuse the rods as they're not damaged.

Finally, here it is!

I couldn't find a replacement Duratec 2.3 block in Europe so I had to order one from California.

GPWerks had both new and used blocks. It took a while to get it but eventually a brand new block arrived.

Beware of TNT Express! They're totally incompetent and should really change their slogan. I'm surprised they manage to deliver any packages at all!

Now I could start to rebuild the engine, I thought, until I dropped a spanner and damaged one of the main bearings.

I ordered new bearings from xpower-engines at eBay and they were very helpful and posted the bearings right away. I can start with other parts in the meantime.

Engine damage

Bad start this year. 

The fuel surge on last trackday caused more damage than I initially thought.

Damaged spark plugs. These are from cylinder #2, #3 and #4

A compression gave the figures 14.5, 12.5, 12.0, 13.5 bar and they're supposed to be within 10%. Some oil in the bad cylinders increased the compression quite a lot. According to Google that puts the suspicion to damaged piston rings. I also see a little bit of smoke from the breather.

I had to take the engine apart.

The pistons are damaged, and so is the block. I put the block into the trunk of the daily driver and asked around among professionals and the verdict is that three pistons are gone, the block can be saved but it would be easier and cheaper to simply buy a new one. Fortunately the head and the rods are not damaged at all.

Damaged block and #3 piston

Damaged piston

I found a good document about piston damage.

Except that, all bearings and everything else looks as new.

The people I've asked about the engine agrees with my theory of what happened - the alternator stopped charging, and when the battery discharged during the day the fuel pump could not keep up on the long Mantorp straight and the engine run lean.

Mantorp first time 2013

This years first trackday was a warm day with blue skies on Mantorp and a huge mix of different types of cars.

Things didn't go that well. It started with me being a bit late.

Then there was a Porsche that spilled oil on a long section of the track. (Those German cars....)
Then someone else went off and one corner was covered with gravel and the track was closed again.
When I finally got the tires warm there was too much traffic and no clear laps.

Engine problems

Lost top end power and the top speed on the straight was a bit too low. It got worse and worse, so I stopped driving and went home instead, worried that there was something very wrong with the engine.

When I got home I did some troubleshooting and found out the alternator warning light connector was broken, and that prevented the battery being charged. (Stupid design!) My speculation is that the battery's voltage went down during the day and caused the fuel pump not being able to keep up the pressure when the fuel demand was peaking, making the engine run lean. Running an engine like this lean is not good at all and could cause fatal pre-ignition.

I need some way to prevent this from happening again.

I would like to be able to log the fuel pressure, and have some warning system for a fuel or oil pressure drop.

Here is a video I found describing how voltage affects the fuel pump flow:
http://www.youtube.com/watch?v=RjykWzDr1Kk

Noise check

A couple of months ago I bought a cheap noise meter from Hong Kong, and today I asked someone to measure the drive-by noise of my car.

The guy told me it made 106.4 dbA!

In many race circuits in this country have from this season a drive-by noise limit of 95dbA.

I started measuring the other cars, and no-one, except a stock Corvette, was below that limit.

Then I moved a little, and all readings changed. Then the wind changed, and the readings changed as well. Then I realized I could not get the same reading twice for the same car.

It seems like measuring noise at a race track is not an exact science.

I refuse to think my car makes as much noise as 106db, but I'm not surprised I have to do something about it if I'd like to drive on other circuits. I just don't know what yet.

What about all the work done this winter?

All good!

The roll cage... stayed in place. 

The suspension bushes hold together. The car felt nice and precise.

The exhaust manifold was not leaking!

The silencer mounts did not break.

No oil spew from the catch tank.

Engine did not leak oil from the front cover

Overall the car feels wonderful. Too bad I was worrying about the engine instead of enjoying myself.

I did not have the aeroscreen mounted as I didn't think it would do much difference. At the end of the straight the force against the helmet was overwhelming. I must put the aeroscreen back on.