Any experiences with a FMU on a otherwise stock system?

[theKbStockpiler]

I'm going to try to adapt a porche 914 D-jetronic system on a 1904 type I engine. I may just end up with the intake system and run something modern to control it but I have to fail first.

Any thoughts or experiences on the use of a Fuel Management Unit like the one in the link? I don't see a lot of talk about having one just to offset the boost in the manifold or using one to get your stock FI system to enrich more because of a add on turbo.
Thanks for your expertise!


https://bloxracing.com/shop/index.php?r ... path=61_93

[66brm]

Wouldn't a normal boost referenced fuel pressure regulator be enough or do you need the variable rate?

[theKbStockpiler]

I think a boost referenced regulator is just for carburation. A carburetor should see about 7psi where as a injector is 40 and up I believe. I read one manual on these and for every pound of boost it will increase the fuel pressure by one pound so it breaks even to supply the carb float chamber. If boost is 14lb the fuel line will have 1 plus the 7 plus the 14 = psi22

[66brm]

The fmu you linked to is a variable ratio regulator, you want one that is1:1 ratio designed for fuel injection

[theKbStockpiler]

FI with a turbo?

[theKbStockpiler]

From reading this;

http://fuelab.com/11-boost-reference-fu ... egulators/

I need a RRFPR. A Boost reference only overcomes the manifold pressure from boost and is not meant to add enrichment,

[66brm]

Correct, you add enrichment through changing the pulse width, ie add more fuel, the regulator just compensates for the increase in manifold pressure by increasing the fuel pressure to maintain the pressure difference of 43psi approximately

[theKbStockpiler]

D-jetronic is a analog system so the whole idea is to enrichen the mixture using a stand alone ,add on device like the rrfpr.

[risk]

I suppose that would work with the Djet system.. that is an old school method before fully tunable efi systems like megasquirt became popular and cheap.. but your injectors will need to be able to open at higher pressures. Some injectors will not operate correctly at much higher fuel pressures.

I have no experience with the FMUs just throwing in my 2cents. I would definitely want some sort of O2 sensor to monitor afr under boost.

[theKbStockpiler]

I found a thread here that has a lot of info pertaining to what I want to do.


http://forums.pelicanparts.com/porsche- ... wners.html


I want to do a PowerBox project with the D-jetronic but as is expected ,hitting the same reality of using a analog system.