D Jet hardware on a bigger engine

[412le]

Is anyone having experience with the capacity of the 1,7 W engine throttle, plenum and intake tubes.
I am thinking about a 1,9 66/96 engine with 1,8 AN 85HP cylinder heads and with a programmable EFI
Cam will be standard W
Hardware from the old W engine will be reused.
As it is an automatic, max rpm will be appr. 5000

Has anyone tried something similar, and do they have some experience to share ?

[Vanagonsgoslow]

The standard 1.7 Djet FI system can probably handle an increase to 1911cc fine on a street car. If it's running lean, you can probably upgrade to 2 liter size fuel injectors. An adjustment to the MPS unit might also be needed for best performance.

[KTPhil]

I think the real limit (especially if you go programmable EFI) is what your question specifies... airflow.

On my Type 3, the practical limit is 1.8l, given the small intake tubes. Type 4 tubes look larger and could probably handle 1.9l without trouble.

But I'm just guessing... I bet it's been done. Maybe ask in the Performance Forum? Buses might have been upgraded and you wont' find their answers in the forum.

[raygreenwood]

Sorry I did not not get into this answer. As KTPHIL notes....the limiting factor is going to be airflow.

The 1.7L stock injectors can handle 1.8L no issues. Same overall volume per hour. The 2.0L injector from the 914 is only really different in the fact that it can support more pulsewidth. The pintle and flow rate is pretty much the same as the 1.7L.

The stock 1.7L runners, TB and plenum work fine to 1.8L. After that and even with certain versions of 1.7L and 1.8L (with better tuning, cam, valves and exhaust)....it can help to put a 2.0L bus TB on either the 1.7L or 1.8L when running 1.7L plenum and runners.

You can get away with 1.7L runners right up to about 2.0 to 2.1L....but you should have the later 2.0L bus TB and probably the bus 2.0 plenum. A full 1.7L intake set up....runners, plenum and TB will be too restricted.

And you are wise to use aftermarket EFI. The problem with D-jet with making significant changes in size and swapping around manifold components is that it greatly screws with the vacuum signature....which really screws with the MPS and fuel tuning. Aftermarket EFI only uses map as a secondary data point and not the main data point for tuning.

Ray