toofast928

Ok let's revisit this. Split Second now has a project 928 turbo with MAF system attached to a Bosch L Injection. $900. Adjustable and calibrated to the AFM. Anyone closer to this goal? Any sponsor willing to make a kit advailable? Sell like hotcakes.

G Man

I'll bet if you contact Kevin at Injection Labs he would be able to help out. He is one of the brains that engineered the Bosch Mass Air system. He used to operate his business just down the road from me in Gardnerville, but moved his operation to Colorado last year. www.injectionlabs.com is the way to contact him.

toofast928

Thanks Jim I sent Kevin a note. Any other ideas anyone?

I myself have already made plans for a voltage conversion box (no software, linear adjustable) Any MAF sensor would work. Just need to program the MAF to show 5.0v around 3000 RPM.

G Man

Toofast. Let me know what Kevin has to say. When I visited him at the shop he was very informative and willing to discuss all subjects relating to Porsche. He seemed to have a genuine interest in 928's. At one point he said he wanted to develop a turbo kit for the 928, however I don't think that ever happened.

toofast928

Yep, I also sent a note to carl 928motorsports. This is my winter project.

Garth S

Toofast,
This AFM - MAF conversion has been done on the M30 3.5l BMW : Some of the points of interest are discussed here . Bruno (back search "racingking") did market such a conversion - so at least the details have been worked out for a Motronic ECU .... I had followed this for a bit with my E34 chassis in mind ...

toofast928

Thanks Garth,
The 928 L Jet operates on a 3.5v - 7.5 voltage. So the MAF Sensor .9 - 5.0 v needs a voltage converter to step up. The 928 Ljet is not Motronic. The only hard part is getting the MAF Sensor programed to output 7.5V around 3000 RPM at a given airflow.

pvoth

The fuel/air computer on the L-jet is a simple analog system.....it seems to me in order in really improve things we need to scrap the whole thing and go digital....then install a MAF along with couple of new sensors like crank sensor etc.
In order to really get the best from these early engines we need something we can tweek with a laptop or other programmer.
It would be nice to just change the brain add the MAF and sensors (affordable off the self even salvage yard used) program and go......it seems to me this shouldnt cost that much $$$$$$....thinking way way less than a grand
adding this along with a larger throttle body and redesigned intake setup would/should show wonderful results....
thoughts??

p

toofast928

I agree Paul upgrading the L Jet fuel system to OBD II is what's really needed but too $$. ECM, Engine harness, macining of intake runners for new injectors, mounting of CAS, tuning time, dyno money.........
The L Jet offers base adjustable timing, injectors that never fail, simple & cheap components, an 02 feedback, and able to fuel the 16v into the 320hp and up. Just needs the MAF to open up the intake.

Herr-Kuhn

You want the system? I hold the key to this... I have the only two AFM to MAF L-Jet 928 conversion cars out there. It is not an easy swap but has been done. That is my car you see on the Split Second website.

The real advantage is in the transient response, not in an overall peak HP number. In fact, the gains might be minimal. You do get a nice crisp throttle after the conversion. There is one achillies heel in that the correction factors off idle make a huge jumps so there is a little off-idle blip you can feel going from very light cruise to throttle. With the MAF conversion and the turbos my car runs really nicely now.

I have toyed with the idea of making such a setup for the L-Jet cars, but the turbo development consumes my spare time at the moment.

I think you might see like 10 HP or something, not huge gains. The real advantage to MAF is a crisper throttle and better transient response. When I pull off throttle, there is a much crisper engine braking effect.

I'd be willing to develop a system...but there would have to be lotsa people interested in the setup. There are some tricks... and I don't mean trick or treat

toofast928

Herr-Kuhn you mean at low speed you feel engine surge?
When you said "more engine braking" you mean with the Turbo installed right? That would make sense at the turbo is an exaust restriction.

Did you have the chance to drive the MAF w/o the turbo? If so what's thats like.

Herr-Kuhn

No, there is a slight off idle blip you can feel when driving...it is because the correction factor rate of change in this area of the map is large. The best way I could describe the throttle is it feels much more connected...that would be with or with out the turbo. Snappier would be a good description. Also, the clear advantage is in tuning the whole fuel curve...

I could easily set up a NA system, but I just don't see the demand being there. By the time you were done it would be like $750-$800 to make it all work properly. People poked fun of the $9K I wanted for twins on the 4.5/4.7 but they forget there was over $1,000 just in fuel components alone. I could have slapped a RRFPR on there for $300 and done it, but I chose the best route possible. Never is the real apples to apples comparison done on this board.

It is nice to be able to hook up the laptop to my old 81 and alter the fuel curve. I run my cars in open loop...the early L-jet isn't that great a system and you can always feel the corrections being made off the O2.

I have not searched lately for MAF comapnies since Pro-M went out earlier this year. I'm sure there are others doing it now. They were one of the few outfits that really could tune with MAF alone for custom applications. Granatelli shut them down...such a shame, they were cost effective and had great products.

This would be a good option for a SC 928 for sure...put the MAF in front of the SC and away you go.

DK

I'm with Mr. Voth on this one - scrap it all for a programmable, but no MAF needed really.
I have converted a CIS 928 to custom EFI, if I can do it anyone can!
Custom EFI is ultimately the way to go for a boosted project.
I used this: www.sdsefi.com

www.eaglesledge.com/cars.htm

hacker-pschorr

Not to burst your bubble, but not everyone with a modified 928 is on Rennlist. Unless that was you at Road America.

toofast928

All that is needed is a MAF. (MAP would be nice but almost impossible working with the L Injection.)
The AFM is a 50mm square restriction in the intake tract. Deleate the AFM alone will yeild more HP and throttle response, also make the most of any other engine mod. 944 guys do it, MB and BMW also. Even Mitsu.
Why reinvent the the fuel system when everythig about L Injection is easy? and cheap...........