It's probably been said before many times. So if there is a thread you can lead me too all well and good.

I am having a 2270 built and was told the DJet FI will not be enough to handle the fuel requirement of this engine. I am not interested in a mechanical carburetor at all. And have no room for that discussion.

Why can’t the DJet keep up? Can it be tweaked or larger injectors installed?

“Chicken Little” type members need not answer, as I don’t need someone’s emotional opinion. What I would like is a down to earth technical understanding.

I am surprised no one made a daughter board to augment the existing ECU to test oxygen or whatever would be pertinent.


Thanks for your time and experience.

Joe D2

It's not just "D-Jet" per se, but a lot of things. The 2.0 plenum and throttle body are sized for a 2.0, so if you're running nearly 30% more displacement, you're going to get about 30% more airflow demand, and the air intake will likely be too small to handle that.

The D-Jet MPS can be adjusted to handle a different fuel curve, but it's a fiddely process that requires a lot of expert knowledge very few people have. Bleyseng seems to have figured out how to do it. The stock injectors are actually quite large, so you could PROBABLY get the D-Jet ECU to keep them open long enough to flow the required amount of fuel, up to around 180hp or so.

Most people who are doing what you want to do will replace the D-Jet MPS and ECU with an aftermarket PEFI ECU, which can be programmed w/o any hard-to-find expertise. It also eliminates the MPS, which will eventually be impossible to rebuild. Dave Hunt has managed to make the stock 2.0 plenum with a bored-out throttle body work on a 2270, but I think he's intending to expand the size of the plenum, too. He's using Megasquirt as his ECU. You can also go to individual throttle bodies (TWM, Jenvey, et al), and get the looks, throttle response, and sound of Webers while still having fuel injection.

Actually I have heard it may be able to handle up to 2.3L. Retune the MPS with an exhaust gas analyzer to set it up right.

Part of the problem is the cam, so what cam are you using?? Even a Web73 is a pain to tune due to the valve overlap to get a good idle.

Far as I can tell there should be plenty of fuel delivery even for a 2270. I should try a test on DaveHunts 2270 and stick back on the Djet parts and tune just to get a baseline MPS. I have pretty much go my 2056 with a Raby 9550 (web73) set up and it rocks!

Well, Dave ya wanna try????

The problem with Djet tuning is you have 3 thats it , 3 tuning tools, idle, partload and WOT. Its a lot of trial and error to get them set up right using a wideband O2 sensor. You don't need a O2 after you set it up as it is hard wired then.

RichD, did you repair the exhaust leaks yet so we can tune yours.

I agree with James with regard to the sizing of the intake setup.

I also agree that the fuel delivery system is not a limitation as far as being able to deliver enough fuel for the 2270 or larger.

But d-jet requires a mild cam to function properly because it is dependent on manifold pressure. An agressive cam disrupts this.

So you would need to use a very mild cam with your 2270. But why are you building a 2270? More power right? So why would you cripple your motor with a mild cam? You wouldn't. Which is why d-jet is a bad choice.

It's like putting a 3.2L six into your car but keeping the stock 165 width tires. Sure, you can do it, but it makes no sense.

Demick

I believe the driveability/tuneability depends on what type of cam you use... I have a 2056 w/Webcam 73 (similar to a Raby (aka RAT) 9550) using stock 1.7L D-Jet setup and am in the process of adjusting the MPS per Bleyseng's (Geoff) instructions. Need to get an LM-1 meter (air/fuel mixture) and get on a dyno to get the WOT (wide open throttle) and cruise setting tuned just right.

Bleyseng is the board's authority on this topic. I believe he is looking into some other mods to the stock system but can't speak on his behalf.

No I drove it home from the historics and parked it. Been working like a dog this week cuz I leaving tomorrow for Monterey
To take in theLaguna Seca round of the 06 MotoGP Championship
GO NICKY!!!
When I return I can get focused and we can finish t up.
sorry for the

I agree with Demick (some day I got to sit down with you and BS about djet)
So far DaveHunts 2.0l intake setup hasn't proven to be too small for his 2270. Its been said by "experts" that the 2.0l can support up to a 2.4L.

Yes, you can "Make" the Djet work its not the best solution in the long run. Its just too limited in its adjustments (Three!) to really given you the benefits of EFI.
I suggest going to MS, SDS or Haltech to really get modern fuel management.
I play with the Djet just to disprove all the ole myths about it....."Cuts off the fuel at 4500rpms, runs lean, can't provide enough fuel, can't be adjusted etc)"


I have been talking with Dave Hunt to comeup with a MS solution thats plug and play including MAPS for 1911's, 2.0L's,2056's and 2270's. You would just install it and drive it.

The system can get adequate fuel and air for a 2270.

I'm not sure how much I can add that's concrete but I can add some conjecture. First for any engine you need enough air and enough fuel. I'm sure the stock injectors can supply more that enough fuel. I believe that my stock intake with a 50mm throttle body will provide enough air. Support for that comes from datalogs which show no decrease in pressure in the plenum under WOT through 6500 rpms.

The question then become will D-jet provide the right amount of fuel for a given rpm and manifold pressure to provide good drivability and performance. This I'm not so sure about. For example, the close to stock engine I pulled out of the car sucked about twice as hard at idle that the 2270 I have now. And, the whole fuel map is moved about 400 rpm’s higher. I have a hard time believing D-jet has that much adjustability.

Dave

so how and when does a less than mild cam come into play...

If at part load and at WOT an agressive cam works ok with DJet, in theory...

Is the problem only at idle?
Can idle be overcome by fooling the circuitry...Im thinking of adding some adjustment on the elec output side of the MPS...to be able to interactively tune the MPS output for a given engine...

what are the elec signals coming out of the MPS for a stock system...does anyone know?
Are there some graphs that plot the manifold pressure verus certain conditions...??

Rich

It's not that a signal comes out of the MPS, but there is a variable inductance (actually 2) between 2 sets of terminals. So it's not like you can just add resistance, capacitance, or voltage to fool the ECU.

When you come up with a simple voltage controlled variable inductor, then you'll be in business.

Demick

My cam is fairly aggressive for fuel injection at least that what I've been told. The fueling map for it is completely different that the one for the earlier engine. The easiest place to see it is at idle. Just off idle it needs more fuel and it requires more fuel at higher rpms. Both of those things are pretty much to be expected. Cruise where fuel cosumtion is less is about 400 rpms higher. Also, it criuses at a higher manifold pressure (less vacuum). The fuel maps look related but, you couldn't just shift the stock one to higher rpms or pressure. They will not superimpose on each other.

Dave

I'm no d-jet expert, but I've studied it enough over the past 6 months to have an opinon....


Certainly things like intake plenum, throttle body sizes are a valid concern, but from a pure engineering point of view if you could get information on the variable inductance ranges for several motors (1.7 , 2.0, 2.2, ad nauseum), it seems plausible that you could calculate the approximate ranges for bigger engines, tune an mps to match broadly and then fine tune in a car.

The reason I believe this is because I have been investigating theorectical means of accomplishing this. From a scientific perspective it seems very doable with a lot of hard work, smarts, and of course some basic contextual data as to the ranges for other engine sizes.

Just my .02....

I too have a 2056 running d-jet with a mild cam(not the 73 web).Can`t remember what cam it is! I bought it many years ago from Ed Atkins along with the Aris pistons. My only real problem has been finding the right head temp sender for a `73 2.0(Anyone know where I can find one?) for the last two years I `ve been playing with radio shack fader switches(potenteomiter?SP?).Tried the 270om resistors attached to the temp switch it would start but not stay running. But I`m close to having it dialed in.pulled over 5000 rpms in 5th gear no sputters last weekend. I only have a flutter when I don`t ease the rpm`s in first gear!

Wow, I asked for it and I got it. Thank you so much for all the practical knowldge you guys shelled out and going easy on the grief. Quite a learning experience.

I do want a more radical cam so seems the easiest route would be after market FI. I'll probably get it from Jake but since there is only 90 days help with it I have to wait until the cam issues are done. Don't want to use up my time while the mechanicals are happening.

Thank you all for chimeing in with all the data.

Joe D

Click to view attachment

Come on Joe! Those are some damn fine chickpics!

Pretty good discussion here. Thanks for the input.

One of these days...

I knew the grief would seep in. LOL "Etu Butus"

Its my understanding that in all engines volumetric efficiency changes as the rpms and loads increase and decrease. An engine’s fuel demand changes along with the efficiency. As Bleyseng mentioned, there are only three adjustment areas in the d-jet mps; idle, partial throttle and wot. The slope created by these data points is constant. The slopes are idle and partial throttle and partial throttle and wot. The slope that has the greatest effect on drivability, in my opinion, is the partial to wot slope. You can adjust the slope to provide enough fuel at peak volumetric efficiency but the mixture will be rich when the efficiency drops at other loads and throttle settings. If the mps slope is adjusted to provide the correct mixture at other loads and throttle settings it will probably be lean at peak efficiency.

I’ve been adjusting mps’s on my two web 73 cammed cars, 75 914 and 77 912E targa engines for several years. Both engines have more but equal compression then stock and have completely different exhausts. I’ve found that because the individual volumetric efficiencies of each engine are different (probably because the exhausts are completely different) the engines require unique mps adjustments. I’ve been able to balance fuel economy with good performance but it has been a time consuming struggle. Both cars have a great idle and my average mileage is around 27-28 mpg. Does this explanation make sense to any one else?

Norton

Sure does and welcome to the qroup.

Dave