Hi@all,

just wanted to share the results of a little race on the german autobahn between my 930 (Kokeln IC, K27, GHL headers, Mille Miglia Exhaust, 1 bar boost spring, Tial wastegate) and a SL 55 AMG:
I won and accelarated him out completelly revving each gear over the redline, only wondering that in 4th gear I was not able to rev over 7000. Afterwards I was driving at mid speed (about 200-210 Km/h) and mid rpm for about 20 min when suddenly a big bang stopped me. Leaving the autobahn and looking under the car I saw steam coming out under high pressure between head and cylinder no.3.

This weekend we took care of the engine and you can see the results on the photos: Typical signs of uncontrolled detonation on piston no.3 and a bullet hole in head and cylinder no.3.
Also detonation marks on piston no. 1 and beginning marks on piston no. 5 and 6.
The mechanical stuff should be fixed in a week, but what I want to cure is the problem of running lean at high rpms under 1+ bar of boost.

Is a fuel enrichment system like the Andial a proper way to go or are there other solutions to solve this problem?
What would the experts suggets?

Thanks and Greetings from Germany

Stefan

 

That is gruesome looking. Why not look into one of the low cost EFI conversions? A wideband AFR sensor would also be in order here.

 

Stefan...tutt....tutt....not good...but you have the right attitude. Heat is always the enemy!! I hope next time around you invest (cheap to buy now) into a good wideband and do some extensive testing and data logging before racing those pesky AMGs.

Forget the Andial Fuel enrichment, you need to have your fuel head modified for more flow two people that can do this:
1) Stephen at Imagine Auto
2) Steve at Rennsport Systems

Both are in the U.S but I am sure they can turn this around quickly for you.

Regards and good luck - Yasin

 

Like Mr slonnrusty says, contach Stephen at Imagine Auto to do a fuel head mod to flow an extra 15-20% of fuel which should be good for 500bhp.

 

Sameer 500HP is a reach. 450HP is a safer level, with the fuel head modification.

 

Being in Germany he most likely has a euro fuel head that is/should be fully capable of handling the mods that he has. I would check on a dyno to see if it is tuned correctly before doing anything else.

 

I would also check the injectors to see if they are flowing at the same rates across all cylinders. Number 3 cylinder is definitely running leaner than #2.
If you are running near 1 bar boost, you should strongly consider a twin-plug setup.

 

Hi@all,

at first thanks alot for the good feedback that leads me into a good direction.
Very good timing indeed that the latest thread exactly discusses the proper topic - fuel head modification.

As far as I have learned till now this might be the best way to start, but cleaning the injectors in addition is also mandatory before rolling road the car.

I will give stephan at imagine a pn to discuss further steps.

Cheers and thanks again
Stefan

 

Hey I've got a set of those!!!!

It happened when I overboosted my car when the wastegate line came loose!

11 days later I was at the track running!!!!

Brian

 

I don't think a Euro fuel head flows enough for continuous high speed running with those mods. Optimum would be EFI, then Imagine Auto's fuel head, and then the Andial set up.

The PO of my car did something like this happen at a DE, he went with the Andial set up after his engine was rebuilt. I still have the Andial fuel enrichment if someone wants to buy it.

 

Never choose the Andial setup. It dumps more fuel through a single injector, it may or may not be distributed evenly into all the cylinders. Especially with our manifolds. With this setup you can have 5 rich cylinders and one lean one to ruin your day. You would not be able to check this with a standard sniffer.

I dissagree on the euro fuel head comment. Mine produces plenty of fuel as shown on a dyno.

 

How about on a big track for an extended run (or the autobahn)?

What's your AFR at full boost and high RPM?

 

That's a good point. At VIR it takes maybe 20 seconds to go down the back straight and the entire time you are at full boost.

Brian

 

I have got to try that track!!!!!!

 

Interesting point, but how would you know either way to suggest that the engine is not getting enough fuel at such times? You can also emphatically state beyond all doubt that our cars run lean at 500 feet elevation when ambient temps are 85 degrees and the relative humidity is 82 and when following a Cayenne, but that doesn't mean it is right.

I think to suggest that the fuel delivery tapers off over time is a bit suspect.

You can't much do a track run with a quality AF gauge hooked up, and the small cheap ones that some people put in there cockpits aren't of much use. The only reliable or controllable method is to test on a dyno.

That said, our CIS based cars are all engineered with a slide rule. There are variations from unit to unit on how much they can flow. Some are good up to 430hp while others are show to be good to 470hp.