Head Gasket Issue.

[AlfaJack]

Has this been seen on other Lampredi blocks? Is it down to the sheer amount of full on power it has had on track?

[jimnielsen]

Jack, I think its really down to an overboost situation that occurred last year. I was convinced it was a head gasket problem.. but no. I saw this 'crack' when I took the head off to replace the gasket a couple of weeks ago. - but though it was just a scratch from some foreign matter - it looks worse now..

We only did one lap with the overboost - of probably 2.2 - 2.5 bar. I don't think this would have been a problem, but we didn't have the injector capacity to provide the fuel for that much boost..blew the exhaust off the car though..

[AlfaJack]

Jack, I think its really down to an overboost situation that occurred last year. I was convinced it was a head gasket problem.. but no. I saw this 'crack' when I took the head off to replace the gasket a couple of weeks ago. - but though it was just a scratch from some foreign matter - it looks worse now..

We only did one lap with the overboost - of probably 2.2 - 2.5 bar. I don't think this would have been a problem, but we didn't have the injector capacity to provide the fuel for that much boost..blew the exhaust off the car though..

Are you running a different MAP sensor? The OEM ECU should not allow anything about 1.5 bar.

[jimnielsen]

at the time I was not using the pierburg valve/IAW P8 to control boost - so the boost level was not under its control, even though I was using the standard MAP sensor for fueling etc..

[jimnielsen]

I removed the pistons from the cracked block today - the good news for me is that they are still just fine - a testament to how robust they are! But I did get a big surprise - two of the oil squirter necks had been broken off by the lower inside skirt of the piston - they were just rattling around loose in the motor!!

There are a few tiny dents in the underside of a couple of the pistons - but this could have easily been fatal. You can see in the pics how the pistons have been hitting all of the squirters so I was lucky that they didn't all break and cause a catastrophe. I don't believe that the oil squirters being broken and the block cracking is related. The crack is 5" long and you can even see it from the water jacket side!

[Steve Webb]

How much clearance was there between the pistons and squirters when you spun the motor round by hand? Is it just down to reduced tolerances when at high rpm or do you think something moved in there.

Like you day, I can't see the squirters having anything to do with the crack.

[SteveNZ]

We have pretty much finished mapping the sm4,
So that won't be a problem.

Jack - 290 hp @ 1.1 bar boost - injectors are maxed!

Thats bloody good power Jim. pity about the block. I'll have a ask around fr a block

[jimnielsen]

Thanks Steve! I appreciate it...

jim~

[jimnielsen]

Steve (webb) - this is the only picture that I have from original assembly that shows a piston (#1) and the oil squirter together. It is close, but I can't remember whether I saw that and thought it would be ok, or just didn't realize that I didn't have enough clearance. There is plenty of room in which to bend the squirters - and I will do just that. I think that with E85 and the very low internal temperatures that the squirters are not needed anyway...


jim..

[jimnielsen]

My new injectors have turned up today... I am currently using the Siemens Deka IV 630cc injectors (384cc is standard). I am changing to the Siemens Deka IV 875 cc/min.

Its amazing how much fuel you need with E85!

jim

[Steve Webb]

Might have missed it, but why are you using E85 Jim? Is it for the higher Octane rating or cooling?

And what sort of mileage do you get from it?

[jimnielsen]

Steve I use it purely because is has excellent protection against detonation for turbo engines. Its also much cheaper than ELF racing fuel!

I am getting about 2km per litre. In a normal configuration E85 cars use about 1.3x volume as petrol cars - but race cars can use 1.6 times because they can be run richer and still run well.. This is why I need new injectors..

384 x 1.6 = 615 - that's 97% of the 630 cc/min that my current injectors can deliver - and on the dyno they were running at 97% capacity! The system was working but there is no headroom for 'fuel trims' - ie to add more fuel if the engine gets hot (etc) And obviously no more fuel to enable boost increase...

[Steve Webb]

I was just asking because of the lower energy content of the E85, but the higher octane of it means you can use more compression/boost.
Are you going to have a switch able map, just in case you need to run it on pump fuel?

[jimnielsen]

no I'm not planning on that steve, but with the Autronic that would be very simple, you could actually make an alternative fuel table and activate it with a physical switch. I am running 9.2:1 compression however, so I would not want to run too much boost on pump fuel..