'76 914 2.0 engine build advice

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shadd356
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Joined: Tue May 02, 2017 8:16 pm

'76 914 2.0 engine build advice

Post by shadd356 » Tue May 02, 2017 9:09 pm

Hey everyone,
I'm currently rebuilding the engine on a 1976 914 2.0. It has the original detuned GC coded engine that came with California emissions D-jet, air pump and catalytic converter.

My goal is to keep the engine fairly original while doing any worthwhile upgrades in the process. I would like to keep the D-jet fuel injection if possible but I don't mind ditching the air pump and cat as I don't live in a state that has strict emissions laws.

Here is what I am thinking so far:
-Reconditioned Stock 2.0 heads (New valves, new guides, cut seats, CC matched chambers, spark plug inserts).
-Stock 71mm crankshaft w/Stock connecting rods.
-96mm P/C set from Aircooled.net (Cast Piston & Biral Cylinder Set, 96mm x 71mm) Has anyone used these? Are they any good for the $360 price?
-Raby 9590 Cam Kit.

I'm guessing that the original detuned california D-jet setup is going to be useless with the big bore pistons/upgraded cam profile, is this correct? If so can I retrofit the computer from a U.S. 1973 spec/ROW/euro spec computer with my system? How much of the cali emissions 75-76 F.I. components jive with the earlier systems? I'm already planning to buy a new D-jet wiring harness and I don't mind tuning a system to work properly (as close to "properly" as I can get with a 41 year old analog computer running an engine it wasn't designed to run)
Any advice is appreciated and thanks in advance!

999argonaut
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Location: The Netherlands

Re: '76 914 2.0 engine build advice

Post by 999argonaut » Thu Jul 06, 2017 4:24 am

I run the same Raby cam with 96mm pistons, stock stroke, stock L-Jet (vs D-Jet) and it works perfect. This cam has been developed to work with the stock FI system and mild cc increases. Just put a half decent exhaust on the car to make it work properly. My car went from 86 to 112 HP at the crank with these mods.

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raygreenwood
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Re: '76 914 2.0 engine build advice

Post by raygreenwood » Mon Jul 10, 2017 7:03 pm

You can do that with the D-jet as well....same mods apply. The D-jet is not California specific.

The distributor curve is California specific and of course the compression is California specific. Simply get rid of the smog pump as noted... bring it back up to normal 2.0L D-jet compression (or better)....use a D-jet distributor that is not California timing curve....something like the 022 905 205P and corresponding advance unit and the 9590 cam and a good exhaust. Use a better coil and get rid of the points.

The D-jet while harder to adjust than L-jet...IS more adjustable than L-jet by far. Yes....you can get that same average 110-115 hp as L-jet but with better throttle response. Point being that with either system its a great combo. Ray

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Piledriver
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Re: '76 914 2.0 engine build advice

Post by Piledriver » Mon Jul 10, 2017 11:09 pm

The LAST thing you want is spark plug inserts, you want 12mm or even 10mm plugs.
The extra meat greatly reduced the cracks forming.
Plug inserts (even assuming they stay in) use a much larger hole, so far more likely to have cracked heads.

Fixing properly involves welding, which requires new seats/machining etc, but that is normal, and bigger valves are "free" at that point. (porting costs extra, pay the man)

The "oversize" inserts are bad, but I suppose a nice stepped silicon bronze insert might work as an effective plug size and crack reducer, but haven't tried that. Yet. (worth lookin at, Ray?)

Plan on at least a new Djet wiring harness (they exist, far better than factory quality even when new)

...but don't ignore the possibility of a fully programmable engine management system.
It can cost about the same, or even less... than a new Djet TPS.

You can probably go MS3+MS3X and fully sequential with LS2 coils for what that Djet harness and a few new DJet parts cost, you can get lots of help tuning it, and the sensors etc can be had at any auto parts store.

If you manage to blow up the ECU, numerous places fix them, if you cannot DIY. (full schematics etc available, and no oddball/obsolete electronic parts)

The factory manifolds etc work great, but you would probably want to use modern injectors... They can be had in the original (or compatible with the hold downs/manifolds) form factor. The ones used from the factory were ~generation one designs, and probably junk after 45 years.

MS2 or MS3 has excellent diagnostics and datalogging... and full schematics and firmware code is available if you are into that.
The fuel maps can be automatically tuned via a wideband O2 and a registered version of Tuner Studio. (works very well with a simple delay table that depends mostly on your exhaust system length)

Of course there is now the Arduino-based setup... Speeduino IIRC.. $180 for a full up assembled ECU, 4 cylinder fully sequential spark and fuel, and GPL firmware all in C.(as well as hardware, fully Open Source) It uses Tuner Studio as well, and can thus also have fuel tables autotuned.
Thats a ~new project but it seems to have no shortage of developers, and there seem to be quite a few running setups.

You could probably stuff that in the original DJet ECU case.
I, for one, regularly embrace our new robot overlords, as I am the guy fixing the robots...

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