Kitcarlson EMS update, Engine Management System Development Options

[Mark Henry]

anyone use cb performance's Digital fuel injection? what about a modified djet w/ dual throttle bodies?

CB's system, all I've heard is that it blows chunks and D-jet will only tolerate minor changes to the cam and intake, dual TB's would just totally F___ it up.

[mightyohm]

If you use multiple TB's, where do you get the vacuum signal, and how do you interpret it?

I would love to have multiple TB's also. But without combining the intakes into one plenum I suspect that it's hard to measure airflow or manifold pressure in a straightforward way.

Porsche did it with MFI by NOT measuring anything except throttle position and RPM. This is an open loop system and very different from the programmable aftermarket systems I have seen.

[Air_Cooled_Nut]

Humm, I've heard that the CB system is pretty good.

To me, a FI system MUST be tunable to whatever it mounts to. If you have an after-market system on a stock engine then later transplant it on another like engine that's been beefed up there should be no problems except for the necessary mapping/tuning i.e. no new parts necessary or else a very limited number of parts changed (injectors, intakes: YES; brains, TPS, etc.: NO).

Using off-the-shelf parts is great! Systems I've seen that are specific to a particular car actually cost more so I don't see that as an advantage.

[Mueller]

Humm, I've heard that the CB system is pretty good

Compared to?? Stock FI, single carb, dual carbs???

The CB system works, it's just that now there are better and cheaper options that work better (or at least have more options or inputs/outputs)

The Megasquirt (and almost all other good PEFI systems) allow one to set it up similar to the factory MFI, basicly TPS and RPM based = Alpha-N, a total pain to setup if you don't know how to tune it, and it does not compensate for changes all that well, if at all

For systems setup to use a MAP sensor, multiple T/Bs are handled by running a line from all of the T/B's to a common port. Some experimenting must go on to optimize hose length and size.

[mightyohm]

I wonder if you could run 4 lines to 4 separate MAP sensors?

I think it could be made to work if there was custom code involved.

[Air_Cooled_Nut]

Oh god, yeah, you could, if you wanted to waste...er, spend...that much money on parts and programming.

[Mark Henry]

My SDS system runs on both the TPS and MPS, or just the TPS, or just the MPS.

You only need one MPS.

A_C_Nut, go and ask about the CB system over on the STF fuel injection Forum. You won't find very many fans.

Kitcarlson has the right idea, a bolt on system would be great.

Below is the link to my SDS install, the big problem with my system is fabracating the crank trigger mounts and disc, welding in a bung for the O2 sensor, coil mount etc. etc... total PITA. The rest was not that bad.

http://www.914world.com/bbs2/index.php?act...f=2&t=5396&st=0

[KitCarlson]

EMS setup:

In answer about Jeff's question about out of the box ready for 914's. I have both 2.0L and 1.7 liter Porsche engines, and 1.6L T1 and T3 VW that will be tuned with the system. These setups could be retrieved from setup library for excellent starting points. Plenty of memory exists for setups.

Setup is very simple at the moment. The VE table is 2D at the moment. I will move to 3D when I get a dyno.

VE closely follows the torque curve of an engine. %'s are entered in table Vs Rpm. A fuel base and fuel scalar #'s are used to bias or grow the table. This enables an engine to be started and roughed in moments. Readings of the total FI pulse in mS and the base and enrichment values are displayed. Also all engine operating parameters are displayed. RPM is updated every 1/3 of a second. All setup values can be changed real time while the engine is running without hesitation. You must at the correct cell for the operating parameter (Rpm, or Temp) for example to feel the change in the engine.

Timing adjustments are similar, two tables (RPM and MAP) and base timing # set with distributor. These curves can be found in service manuals as starting points. Additional tables for temperature and TPS timing controls may be added.

There are also the typical starting fuel table Vs time, Enrichment vs CHT Temperature, and TPS and MAP derivative controls. The enrichment Vs air intake temperature is part of the fuel calculation.

Alpha-N (TPS fuel) is also implemented and can be used in conjunction with the speed density for wild cam applications. I have not played with it much yet.

This is what exists at the moment, things may change as part of the development process.

I have a G-Tech and 5-Gas.

I have been thinking about a brake dyno using an old VW swing axle trans. Locking the differential, and operating the brakes regulated by rpm could give load points long enough for gas tests, with cooling periods. Might be able to measure a crude torque at spring plate (Torsion bar movement). Has this ever been done??