I have a question on using an 82 as a base for S/C:

It has an L-jet with Euro cams and MSDS headers. Other than that, the motor is stock.

With the L-jet, this cannot deliver the amount of fuel required for a S/C. Has anyone brought the Inj system over to and K-jet or L-H, if so what kind of cost and the end result.
Thanks
Mark

 

Who says L-Jet can't fuel a S/C? I pulled 330 HP and was still too rich. Enzo broke the 440 mark. Be nice to convert to MAF but continuous injection is perfect for S/C application.

 

yah see Enzo's build....

 

I guess my PM didn't make any sense. I used one of these:



With an S4 pump fuel will run out around 390-400hp so that IMO is the limit of the L-Jet system. Yes I hit 400rwhp, but not very well. It's not a setup I would ever duplicate, this has been 100% experimental. Next step is going beyond L-Jet with a different igniton system & probably MAF.

I've been working on a "conclusion" write-up, not quite done yet.

Bottom line is the igniton system gave up past 10-11 psi with stock compression and stock range plug gap. Closing the gap helped pull a few more rpm & psi, then fuel ran out.
Problem with running such a tight gap is gold running, it is not a happy engine until it's warmed up.

Someone else asked about placement of the AFM (barn door) - doesn't matter. Keep it in the stock location so when cruising without boost the car runs normally.
IMO the #1 rule of these projects is keep as much as you can 100% stock (for a street car). Change only what you have to or driveability will suffer.
This is why I never messed with different intakes, cames heads etc.... I only addressed the exahust because the original setup is horrible (proved this with my 79's dyno chart).

So do I recommend supercharging L-Jet cars? Hell yes - 100%. I don't think I would push a stock engine past 11psi though. At 9.5 psi the car ran perfect, made over 350rwhp (had room to go, was running rich). So with my new open intake I might go to a slightly larger pulley for now, bring the boost down a bit until I decide on what system to switch to.

Before I ever put boost into my car I replaced everything except the rings & bearings (ended up swapping the rod bearings later, long story).
So every piece of rubber, gasket etc... was stripped off & replaced.

I know I'm going to get some slack over this post from a few people

 

Great post Hacker. I was the one asking about relocating the AFM. The idea was to move the AFM to the inlet side of the compressor. This way the L-Jet will still fuel properly up to its max and you should retain the great driveability you have w/ a stock car. When tuning you will be able to see when you run out of fuel and use an AIC (additional injector/s controller) to fuel the top end. There are quite a few companies who make these stand alone systems that bring in extra fuel based on RPM and boost inputs and you program the parameters. Here is one such system http://www.rbracing-rsr.com/rsraic400.htm & here is another http://www.splitsec.com/products/datapdfs/aic1ds.pdf . Has anyone here had any experience with these? HKS also makes a similar system but theres can drive up to 8 additional injectors. This may help your fueling issues but it won't address your ignition issues.

 

I see no reason to move the AFM - works fine where it is on my car.

Z and I talked about a 9th injector, problem is there is no way all eight cylinders will receive an equal amount of fuel. IMO a dangerous situation waiting to happen.

Larger injectors are the answer, prolbem is there is no way that I know of to program the L-Jet system for non-boost driving.

I might try the MSD box next, tinker with replacing the stock Bosch ignition box (tach signal seams to be the big hurdle). That will not solve my fuel problem but it should help with driveability.

 

I respectfully disagree. Larger injectors will effect low RPM/off boost driving. Adding an additional injector to each intake runner will insure that each cylinder recieves equal fuel. This setup should allow you to leave the fuel pressure alone too. The additional injectors come on board as boost increases
and fuel needs rise. Keeping the AFM as a draw through system should allow it to accurately meter the air since it will still be at one atmosphere. At some point the L-Jet will be maxed out. This is where the additional injectors will supplement the fuel supply.

Please don't take my posts to be argumentative. I have been thinking about this for awhile and just need peer review to flush out my ideas. Please feel free to shoot holes in my theory.

 

I said adding a 9th injector, not 8 more.
Before I go through that much trouble I'll switch to LH.

The AFM is maxed out long before boost kicks in anyway, no matter where you put it.

 

So with these modified setups, why would you not just go with a modern management system? It just seems to me that the investment in time and money would pay big dividends by going to TEC3, or even Haltec or full Motec systems. I know they are money, but can be had on the used market reasonably.

 

That's the way I see it. I pushed the stock setup as far as I could make it go. Next step is to scrap it for something else.

I am going to try and boost the ignition system, see what happens. If it works it will not be wasted since my track car will benefit from it.

 

I think there is a common misconception about idle quality and big injectors. I'm running 60 pound injectors on my Audi. I can get a rock solid idle at 500 rpm.

I think if anyone wants to go beyond what Enzo did, get bigger injectors and run something like a Haltech E6. They go for a few hundred bucks on EBay. With that you can drive a much more powerful ignition easily.

 

I didn't realize I had to be so specific. Let me clarify. Larger injectors will effect your low RPM/off boost performance if you don't have a way to shorten the pulse duration.

 

True...

 

Fabio, the L jet systems do use an oxy sensor, so there should be some closed loop effect keeping the mixture correct as you change injector size. I don't know the limitation of what they do or do not do with the oxy sensor though...some how it is used in combination with the flappy valve between idle and WOT, I think. I don't know if it is used at idle. In theory the L jet brain should not be hard to modify. As I understand it it is basically a analog pulse shaper which takes the ignition pulse and creates a longer or shorter version of it based on the input from the sensors. I have thought about reverse engineering one, but my current car is CIS, so why bother. Unless there are ASICs, it should be possible to figure it out and modify it. I don't really know of who else might have looked at this in detail. Perhaps John Speake?

 

Has anyone Megasquirted an L-jet yet?
That was the route I was going to take. Since it's a MAP system you'd be able to ditch the barn door without having to add a MAF. But I think you would probably need to fit a different TB or maybe add a TPS to the existing.