Now we are very close to issuing the SharkTuner for EZ-F which is mostly aimed at s/c 85/86 cars, I need your help/experiences with sutiable knock alarm systems for these cars.

I am going to carry out sopme experiments with a KnockLite on my own 86 Euro 16v.

As you will realise, the EZ-F has no built in knock system, so there is no automatic knock control by spark retard as there is with the S4 and later cars.

One problem is that even when you have fitted a knock alert box, you need to be confident that it can be set to give relaible warnings as soon as detonation occurrs.

It is clear that the stock 85/86 EZ-F has a large safety margin mapped in by Porsche. Most of the gains attributed to the Autothority chips I am sure are due to taking out some of those safety margins by advancing the igntion at various points.

My assumption is that the s/c 85/86 cars which typically are running 5-6psi are surviving because they are using up most of that safety margin.

Has anyone tried Autothority chips with a s/c 85/86 ?

When you add higher boost than 5-6psi , you may be able still to add a little advance at the low end before any significant boost is made, but most likely, when the high boost builds it will be necessary to take out advance.

I don't have a s/c 85/86 car to use for development work here, so it is up to you, the potential ST
EZ-F customers to help in the development of a safe knock alert system for ST the EZ-F.

Any comments welcome ?

Once we have a knock alert system, I believe a knock signal can then be used to retard the igntion as a safety masure in the EZ-F using the ST...

 

I blew a head gasket on a sc 85 auto with AA chips running about 6psi non-intercooled. When we tore the engine down one cylinder (the one exactly where the gasket failed) also had a gouge in the cylinder that allowed more blow by from crankase pressure. Not sure what caused the failure but have always thought the increased cylinder pressure contributed the most. In reality it sounds like it could have been a combination of the chips and the scar in the cylinder.

 

I blew a head gasket on a sc 85 auto with AA chips running about 6psi non-intercooled. When we tore the engine down one cylinder (the one exactly where the gasket failed) also had a gouge in the cylinder that allowed more blow by from crankase pressure. Not sure what caused the failure but have always thought the increased cylinder pressure contributed the most. It sounds like it could have been a combination of the chips and the scar in the cylinder.

 

Thanks Abby - that's very useful knowledge to add to the database.....

Anyone else ?

 

John:

Just to confirm where I am with my 85 MY I have been running 7 PSI with an intercooler on stock chips and with the low octane loop plugged together for a little over 2 years now. I have had the car at various DE's with up to 90 degree ambient temperature and the temperature guage above the last white mark for 30 -40 minute run groups and no failures. Overall I would say I have about 16 days at the track with 3-4 sessions a day.

Hope that helps..... I would say that I am in the "safe and fat" range.

Ken B

 

Hi Ken,
Thanks for that. As you probably have gathered, the octane loop will give 3 deg retard to the standard "conservatively" mapped stock 85/86 chips.

Did you use the Octane loop as a precaution, or because you thought you had heard pinging ?

Do you have type of knock alert system ?

 

John:

I use the loop as a precaution during track events only and actually for a couple of late fall events when we have had temperatures in the 50's I have unplugged the loop. I also leave it unplugged for street use, even with spirited driving.

Luckily, I have never heard any pinging in either instance and I do NOT have a knock alert system.

I should probably also mention that I am running one of the twinscrews, an Autorotor 424 this big unit seems to be pretty effecient. I also have an isolated cold air intake through the fender well and my exhaust is heat wrapped all of the way from the heads to the exhaust tip (reducing under hood temps)....I think these little things have also helped me stay away from detonation.

Regards,

Ken B

 

I took out a degree of timing between 2000 and 3000 rpm when I tuned for 7 + pounds of non intercooled boost. When the intake reaches 120 degrees it retards timing 3 degrees. I am making the same horsepower and more torque with 5.5 pounds of intercooled boost. Does the octane loop plus high intake temp take out a total of 6 degrees of timing?

 

John,

Been running 10lbs boost for over a year now and no issues . My only problem is in the Vegas summer heat with my intake tubing still under the hood, the temps get "blinding hot". I see a loss of boost (approx 3lbs) after I've been driving her during the hot days.

FYI...I've always left the "pig tail" disconnected.

 

Same circuit. The EZ octane loop grounds the input of the air temp sensor.

 

Thanks, that makes sense.

 

Yes, just the 3 degrees retard would be obtained. You will be able to program that back to as much as 29deg with the EZ-F SharkTuner

 

The safest way to tune these cars is going to be on a dyno. Louie states that there are quite a few degrees advance between maximum power and start of detonation point. In fact the power has dropped slightly after max power as you approach the detonation point.

A knock alert system would also be a good back up, in case of an unexpected issue causing knock at any time.