Stock EFI limits, is it RPM or HP? Options

[qa1142]

Ok, so I am still thinking through my winter engine project. I plan to stay in "stock" class so EFI is staying. I have an L jet on my 1.8L, I have "spair" 1976 L Jet, and I have a D jet that came with my 2.0L project motor.

2.0L give longer stroke and more torque (right) while staying 1.8L would give faster revs and (more rpm??)

So what is CFM / RPM / power limits of each injection system. Seams like L jet with air flow sensor would keep mix better at all RPM. Is that true? Would I run out of CFM if I bolt it to a 2.0L?

I am thinking, RAT EFI cam to match D or L jet, Mallory if L jet, 2.0L heads reworked by Len that match, then either 1.8 or 2.0 basically stock Piston / cyl kit from Jake also.

Let me hear your "un-biased" (IMG:http://www.914world.com/bbs2/html/emoticons/slap.gif) inputs, I need to start ordering parts soon. (IMG:http://www.914world.com/bbs2/html/emoticons/mueba.gif)

[Mueller]

QUOTE (qa1142 @ Sep 5 2005, 08:42 AM)

Ok, so I am still thinking through my winter engine project. I plan to stay in "stock" class so EFI is staying. I have an L jet on my 1.8L, I have "spair" 1976 L Jet, and I have a D jet that came with my 2.0L project motor. 2.0L give longer stroke and more torque (right) while staying 1.8L would give faster revs and (more rpm??) So what is CFM / RPM / power limits of each injection system. Seams like L jet with air flow sensor would keep mix better at all RPM. Is that true? Would I run out of CFM if I bolt it to a 2.0L? I am thinking, RAT EFI cam to match D or L jet, Mallory if L jet, 2.0L heads reworked by Len that match, then either 1.8 or 2.0 basically stock Piston / cyl kit from Jake also. Let me hear your "un-biased" (IMG:http://www.914world.com/bbs2/html/emoticons/slap.gif) inputs, I need to start ordering parts soon. (IMG:http://www.914world.com/bbs2/html/emoticons/mueba.gif)

well, "stock" is "stock", so the mods you are talking about is not allowed more than likely and would be "cheating" (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

with the L-Jet, I've run it on a higher compression 2.0 motor with a header, ran great, but I never checked the O2 levels or dyno'd it.....I do know the car ran great as does a few other people that rode in it...

with the L-jet, once you reach a certain RPM, the flapper is pretty much wide open and the ECU then just adds fuel based on RPM....it does work, but at what RPM or HP level will it lean out at?? I'm sure you could monitor the O2 level and compensate for it if you understand the fuel injection thru and thru...the easiest method would be to tie into the CHT circuit and "fake" it out so that it adds more fuel at the RPM threshold due to it thinking the

both the D-Jet and L-Jet are going to be limited somewhat....since more people have tweaked the D-jet, you are safer going that route unless you want to learn how to optimize the L-Jet...personally if I "had" to stick with one of the factory FI's, I'd go with L-jet since that is what I was more comfortable working with.

Oh yea, you can run a Mallory with D-jet, I've done it.
The mechanical trigger points are replaced with an optical trigger circuit. Do a search for "mallory" and "circuit" using my name. Pretty easy, cost about $10 or so I think

[Bleyseng]

You will also have to improve the stock valve springs as they give up around 4500rpms.
Djet is suppose to work great until about 5000rpms, then it starts to "lean out" according to "Myth". I am going to do some data logging soon to see if this is the case.

Previous dyno work of stockish 2.0l's shows serious hp drops at about 5000rpms (hmm, like a 500ft cliff really). This is probably the valve springs crapping out.


Ljet is still a unknown to me, but as Mike says the flap eventually is wide open so at some point you will run lean or rather inacutate fuel metering.


( . )( . )

[TravisNeff]

I know nothing about LJET, but it uses the same cam as the DJET. And the stock cam falls on it's face at 5K, you can't really add much cam and still have DJET run OK, I assume similarly with LJET. If you had an aftermarket injection kit allowing you to run a much different cam - your ceiling raises a bunch.

[sean_v8_914]

jake makes a cam t run w both stock FIs

[sean_v8_914]

I want to do some back-reading about Meullers FI posts and other non stock FI posts but my searches dont work. what do I need to type in and where? (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif)

[Jake Raby]

9010 for D jet and 9550 for L jet.. The 9550 sells so fast that I cannot keep them in stock at all.

[Rick_Eberle]

The Renault 17TS squeezed 108 hp @ 6000 RPM out of 1565cc using D-Jet. I'd like to know how their cam profile compares to ours. I would imagine that water cooling helps, though.

These parts look familiar: Diagram