Breaker wrote:I'm considering rebuilding a 2.0, and am tempted to keep everything stock, but then again...
Anyone running Raby's 9550 cam, with stock 2.0 D-jetronic F.I.? I've read that the MPS needs adjusting, etc.. so I was wondering if mileage suffers, and by how much... I've heard lots of good things about that cam, just wondering what the downsides are.
And the MassIVe type 4 website says not to use greater than 8.0 compression. This Euro 2.0 is stock at 8.2, if I remember correctly. I ask because I think raby will only give advice on purchase of an entire engine kit. Any experience?
Any input welcome, thanks.
I will be installing my 9550 in my 412 engine (which uses the exact same series of MPS as the 914 2.0L...just different part # series but exact cross match). I will be using 8.5:1 compression.
Jake has very good reasons for his low compression reccmendation. Its because with normal effort he system has a habit of running the system lean at part throttle settings.
I have been working with D-jet most of my life...since 15...and this problem can be gotten around with careful tuning. You have to do it all...and you can't cut corners or you will have lean spots at part throttle settings.
About 99.5% of all D-jet owners are too lazy or scared to do what is required to run this system like it can be run.
(1) rebuild your distributor and get the slop out of it and the advance weight system.
(2) make a few mods to get adjustability to advance and retard...this is virtually free to do.
(3) I like pertronix...because it does not diminish voltage with wear....but suit yourself...just get a btter coil for Gods sake because at 18Kv...which is 10-12Kv actual on the stock engine..it was seriously underignited.
I can help you with all of the ignition mods...just contact me.
(4) get a better cam...which you have
(5) solid spacers,swivel feet
(6) get much better than factory stock fuel pressure stability. You need 1/2 psi stability. Make a fuel accumulator with a a return line bleed oriifice. Bet a better pump than stock...or get a feeder for your d-jet or Ford pump.
(7) Get the best exhaust you can afford.
Important:
(8) Ideally you should get a new EFI harness. The factory harness has sorry connectors when new (design wise). they do not age well. There are two people one one on STF and one on Samba that sell factory perfect repros...great work and worth the $. 90% of all EFI faults (e4specially D-jet)...and poor tunability...are harness related.
(9) If you are not willing to fully adjust...all three adjustments...in the MPS....stop right now and give up. These are not hard to do...just tedious.
(10) Get a ballast resistor for the CHT....you will need one. A fair portion of the lean situation that happens in part throttle enrichment problems is due to im,proper fuel mixture baseline from the CHT. Contact me if you need help.
(11) The 2.0L 914 intake plenum was the worst of the...it could use a couple of simple mods.
Jake has to warrant his parts and systems. I would never tell anyone to do something to void their warranty....but the simple facts are this:
D-jet does not run well when tuned for performance.... in any configuration...when it uses low compression. 8.0;1 is just hanging on by the skin of its teeth. Its survivable with stock levels of tuning with stock condition parts....but the fuel mixture will not be ideal at either idle or WOT with compression this low....but it will be safe.
VW/Porsche knew this as well. Its why the system with 1.7L got the odd compression of 8.2:1. that little bit of difference makes a world of difference in MPS vacuum signaturestability...and the ability to tune it.
I know for a fact that 8.4;1 through about 8.6:1 are a very nice sweet spot for tuned out D-jet. It can be done and will give you,............much better running and tuning than any factory ...either Porsche of VW ....gave it. But....you have to be willing to do everything correctly. No skimping...no cutting corners. You have to improve virtually every component in the system. Ray