Transaxle

The DME/KLR combination of the 951 is a great system with a lot of flexibility and safety. But it is limited to 14.5 psi boost. So most people switch to add-on boost controllers to remove that limit. In most cases with the loss of the KLR safety mechanism.

But specially on the German autobahn it is not wise to drive a 951 without the KLR...

Looking at the KLR hardware, the limiting factor is obvious. The internal boost sensor is a 200 kPA version - it can't read pressure above 14,5 psi. Replacing that sensor with a modern 250 kPA (22 psi) sensor is fairly easy. In addition the hardware needs to be recalibrated and the boost control map needs to be updated. And you will need to modify the DME chip to meet the new boost settings.

But then the system is able to control boost up to 22 psi. You may not want to do that - but with a stock K26.8 engine you can easily drive 16-17 psi at mid engine speed with full knock sensing, ignition retarding, boost correction and failure recognition.

Attached are pictures of my prototype hardware.

OZ951

Nice work Transaxle, great project. Have you done the chip re-mapping yet ?

Geneqco

+1 Transaxle - great documentation too! There was a thread aseking about this just a few ago.

Transaxle

The remapping depends on the configuration of the car.

I'm currently concentrated on a stock 90' 951 configuration.

Attached is the current status of the KLR boost map in kPA.

And this video shows how the system follows the settings (Quicktime needed)

http://www.mytransaxle.de/video/klr02.3gp

But everything is still under development...

Diver944

Good work Tom. If you get this working properly with full safety features and boost control up to 22psi I think it will be a big hit

evil 944t

Hmm, good job. Looks good!

Acetylene

VERY,VERY interested in following the progress of this - very nice work.

Mike Murcia

Excellent. I'll have to dig through my spare parts to see if I still have the cycling valve. Great work.

rberry951

Looks like the Maxtronic needs to grow into a two emulator in one box system.

Great work Tom!

Regards,
Russell

Keithr726

I have two 86 KLRs, and I've noticed that that chip is different between the two. One is a lot bigger than the other. Any ideas why?

pics here..
https://rennlist.com/forums/944-turbo-and-turbo-s-forum/364972-questions-about-24pin-klrs-and-autothority-chips-sry-56k.html

Pauerman

Tom,

This updated 250 kPA pressure sensor's job is to control the factory cycling valve to achieve knock protection at higher boost settings correct? Am I correct in saying that the KLR will pull timing and reduce boost when it encounters knock?

So, with the 200 kPA sensor, is the KLR still pulling increments of timing in when it detects knock at boost settings above 14.5 psi?

Will higher boost settings be controlled by afermarket options like the jetted banjo, LBE or Accuboost, or will boost control be handled through the KLR and the cycling valve?

Transaxle

There were several boost sensor circuits used with different characteristics. Also from 87 on they used a completly different sensor packed in a plastic box. Be carefull with changeing chips with different sensors since they are not compatible.

Transaxle

It will first pull timing in two steps á 3° and if that does not help it will reduce boost.

Yes - in two steps of 3°.

It will be handled through the KLR and cycling valve. There is no need for any modification. Depending on the target boost you may need to adjust the inline of the CV.

hosrom_951

very smart!

danny951

well done! I think you have finally created the best bang for the buck 951 upgrade ever.

Even a stock 26 car can now safely run 17 - 18 psi and gain a very nice HP boost for very low cost.