stock efi

olivajeep · Post by **olivajeep** » Tue Feb 13, 2007 1:57 pm

will the stock efi (djet) work with 96mm pistons and cyl keeping the 71mm stroke (914 2.0) or is the little increas just to much motor for the efi.

Dave_Darling · Post by **Dave_Darling** » Tue Feb 13, 2007 10:32 pm

It can be made to work... It should be "OK" even without any real modifications, but stick it on a dyno with a Wide-Band O2 meter (or get your own WBO2 like the Innovate one and drive a lot) so you can tweak the various adjustments in the system and get the mixture where you want it.

What adjustments? See: http://members.rennlist.com/pbanders for tons and tons of D-jet info, including the stuff that can be adjusted.

--DD

Bleyseng · Post by **Bleyseng** » Wed Feb 14, 2007 7:35 am

It will be fine if the Djet system on your engine is complete with the correct matching parts.
Problems arise with people mixing and matching the parts. I just worked on a 914 2.0L with 1.7l injectors and other mechanics couldn't figure out its lean missing/hesitation problems. DuH!

olivajeep · Post by **olivajeep** » Wed Feb 14, 2007 12:36 pm

i thought it might be fine. its only a little increase. what is the biggest i might be able to go (bore and stroke) before i start having problems. i would like to view my options since im going with new pistons a cyl.

raygreenwood · Post by **raygreenwood** » Wed Feb 14, 2007 2:00 pm

Others may have better advice.....but I would not stray much over the stock 71mm stroke. Yes it can be done.....but to use a longer stroke and get all of the benefit it could provide, it will entail a bit different cam than the stock cam (which you should dump anyway).
With D-jet, valve overlap is very important as well as the intake valve timing pattern. Excessive lift is also a detriment.

In my experience the complete system from a 2.0 with D-jet can be tweeked to run up to about a 2.2. I think it could actually go further...but at that point the plenum and runners will generally not support much larger.
The 1.7 system can also be tweeked to work with just under a 2.0...but you generally need a better cam, exhaust, 2.0 914 runners and a slightly larger TB. Ray

olivajeep · Post by **olivajeep** » Wed Feb 14, 2007 2:51 pm

so let say i keep the stroke at 71mm and go to 96mm bore what cam do you think will work best. also in the future i will be running sds efi and a turbo just thought i could get the motor done first.

raygreenwood · Post by **raygreenwood** » Wed Feb 14, 2007 3:36 pm

If you were keeping the stock injection....keeping stock stroke and 96 bore and changing nothing else...an excellent upgrade is the Webcam #73 with matching lifters.
It is a slight increase in lift and duration if memory serves....but utilizes the early 411 pattern intake valve timing and overlap so it is friendly to D-jet. By the way...the VW 411 and 412 used the exact cam with D-jet as the 2.0 Liter. The only difference was that theearly 411 pattern (not seen on this continent) had slightly different intake valve timing.

That being said, Jake Raby offers several unique versions of the Web #73 that should be even better. They are a split pattern from what I am told....to allow much better exhaust breathing. I have not used one yet...but will be soon. You should contact his store and tell him what your engine and exhaust specs are...and he can set you up with the correct cam. Ray

olivajeep · Post by **olivajeep** » Wed Feb 14, 2007 5:42 pm

thanks ray i will do that

Dave_Darling · Post by **Dave_Darling** » Wed Feb 14, 2007 6:26 pm

Note that the more you change on the engine, the less well the EFI will be able to deal, generally speaking. Chances are good that a 2056cc with a Web 73 (or Raby EFI cam) will require quite a bit of fiddling with all of the available adjustments to get it to run half-decently, and maybe more than that to get it completely decent.

--DD

raygreenwood · Post by **raygreenwood** » Thu Feb 15, 2007 9:02 am

Yes....Dave is spot on. Things like increase in compression are generally not the largest problems (within reason). Displacement changes that outrun the manifolds will change the vacuum signature and response of the MPS. Larger valves are another facet (but necessary) It will take quite a bit of tuning work. But it is do-able. Ray