9550 mileage

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Breaker
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9550 mileage

Post by Breaker » Mon Feb 20, 2012 2:25 am

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.

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Piledriver
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Re: 9550 mileage

Post by Piledriver » Tue Feb 21, 2012 6:23 am

AFAIK Jake will provide specific advise once you actually purchase a complete valvetrain kit.
I, for one, regularly embrace our new robot overlords, as I am the guy fixing the robots...

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bradey bunch
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Re: 9550 mileage

Post by bradey bunch » Tue Feb 21, 2012 9:08 am

I would try asking on his forums, I am sure some of his customers will chime in, and maybe he will too.

http://forums.aircooledtechnology.com/index.php

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raygreenwood
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Re: 9550 mileage

Post by raygreenwood » Sun Apr 15, 2012 6:23 pm

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

68Ghia
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Re: 9550 mileage

Post by 68Ghia » Sat May 05, 2012 9:18 am

Haven't been around for a while and this might be too late but to answer your question: I just built a 2.0 GC w/ Raby's 9550 cam and "complete" drive train. Compression set # 8:1 and stock DJet with an adjusted MPS. Just completed a 996 mile rt to AZ with my wife (and several other teeners). Hiway speeds were 80-90mph and town driving was about 1.5hr's total. Our mpg was a little over 37mpg.

Frank914
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Re: 9550 mileage

Post by Frank914 » Thu Jun 11, 2015 6:08 am

Hello, I'm new here and about to rebuild my 2.0 914.

I'm interested which ignition timing works perfect for the 9950 or 9590 cam with 2056cc and a CR of 8,5:1?
And how could you achieve it by using the original distributor?

Does anybody have experience with that setup?

Jake told me initial timing should be 14°BTDC to enable me to run spec idle for emissions testing.

Thank you and best Regards,
Frank

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raygreenwood
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Re: 9550 mileage

Post by raygreenwood » Fri Jul 24, 2015 10:08 am

Wow...sorry I did not see this in June.

Yes.....go with Jakes recomendation. Personally......I have fiund that with any type 4 with D-jet...even stock.......a bare minimum of 10° btdc at idle is required for stable idle timing. I used 12° with the web 73.

You need to pull the breaker plate and take some alop out of the smaller spring and its mounting pin. It gets weak, with age.

The common thought most will tell you.....to time with hoses off at max advance.....and just let idle timing fall where it will....does not, work well with D-jet.

This is, because poorly controlled off idle advance and timing, causes a very momentary vacuum signature dip due to poor combustion efficiency. Since this is a MAP controlled system.....that screws up fuel mixture.

It, will also cause you set the baseline fuel mixture excessively lean on the MPS...to keep from geeting this flat rich spot.

The other problem is that moving the distributor slightly, to give you better idle timing ....changes the injection timing because injection timing is set by the trigger points in the, distributor. When injection timing on D-jet gets far, enough off of correct at idle......it screws with the vacuum signature...which screws with pulsewidth at, the MPS....which screws with fuel pressure stability at idle....which you can with an accurate fuel gauge.
So you may need to slot the trigger point screw holes so you can, return the trigger platr to center to keep fuel pressure stable at idle when you advance, the distributor.

Also....the advance can should have an adjusting screw in the center of the can. The best fan for 914, and 411/412....arm number,917......had one. You can install one on any advance can.

Also...if you system uses a retard side on the advance...which helps to keep the advance from being choppy at idle....you can install a small set, screw in the can to keep the can frkm over, retarring at idle. Ray

Frank914
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Re: 9550 mileage

Post by Frank914 » Thu Jul 30, 2015 11:42 am

Hi Ray,

thanks for your input.

The distributor has advance and retard but I'm not planning to use the retard.

I'll slot the holes of the trigger plate to retard trigger timing to original when I advance initial timing and limit the travel of the centrifugal weights to avoid over advance at higher RPM.

Did you build your engine with a CR of 8.5:1? Does it run well with that CR and D-Jet?

Best Regards,
Frank

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raygreenwood
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Re: 9550 mileage

Post by raygreenwood » Thu Jul 30, 2015 4:19 pm

I have not assembled the engine yet. Everything is ready. But....there is no point until the car is a roller. That may be a couple more months. Just finishing the suspension.

Yes....it looks like 8.5 or 8.6:1 will be the final. The heads came back recently but I have not had time to do a final cc.

I have already run D-jet at 8.5:1.....the higher compression is the way to go. It makes the vacuum signature more uniform. This allows tighter tuning.

The vacuum retard is very useful on a tightly tuned engine....dont count it out. The retard pulls the ignition out of advance.....only when the throttle is all the way closed.

Depending on which D-jet system and TPS.....I typically disconnect the fuel cut-off function. The TPS system, especially late build Bosch TPS are not sensitive enough resolution wise...at the proper adjustment point...to make a quick enough transition from off-throttle to on throttle and back.....without creating a lean or dead spot.

This means that at high rpm overrun.....going through a corner and lifting off the gas or deceleration onto a ramp.....leaves you with high rpm and advance....and very lean fuel mixture. Although you still have the mechanical in the distributor....pulling back the vacuum advance with the retard unit at closed throttle helps keep this under control....less risk of detonation.

Having a stop on the retard prevents ever having the idle drop below exactly what you want...while being able to keep the idle higher than stock (a necessity on tuned out D-jet to keep the idle very close to the immediate advance point of the centrifugal advance)....and also a necessity on the Web 73....and from what Jake noted....on his cam designs as well. Typically 900-1000 rpm idle will run and tune much better with D-jet.

Also using a retard unit with a disconnected fuel shut off can sometimes allow you to eiither tunne the deceleration valve very tight...or in some cases...omit it. Ray

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