Jimmy325i

I'm about to rebuild and port a GSL-SE 6 port 13b engine and am wondering what will need to be done to the fuel management to accomodate the 40% increase in power?

I'm a 2nd gen guy who has no experience with the 1st gen engine management what so ever. I'm helping a buddy of mine with his car and want to know what it'll take to get the thing running properly without going stand alone ecu or carbs.

Will bumping the injector size up or boosting the fuel pressure up be enough to compensate for the additional air flow or will some things need to be modified in other ways?

peejay

The stock setup should work.

You do not want to "compensate" for additional airflow because the stock ECU does it automatically. That is the beauty of EFI that directly measures airflow.

The stock injectors are good to about 200hp or thereabouts.

Jimmy325i

it doesn't get screwed up from the airflow being so much greater than it "should be" due to the porting?

the problem with most EFI's is that the computers cant handle a moded engine because they run outside of parameters set by the factory as "normal." so anything too major gets the comp into limp dick mode or floods the hell out of it.

Directfreak

iTrader: (2)

I has a streetported GSL-SE 13B with the stock FI. you'll be fine. Nothing to do except get a good exhaust, and maybe a cone filter (I had those).

Back then Pineapple Racing sleeves disn't exist either, a worthwhile upgrade IMO.

The GSL-SE FI system is analog, so you don't have to worry about limp-home modes.

Jimmy325i

This car already has a header and pineapple sleeves.

I have a 2nd gen that I heavily ported and used the TII intermediate housing (also ported) in, and it pulls pretty darn hard compaired to the stock GSL-SE in my buddies car. I also have all the exhaust and intake mods done with the exception of porting the intake manifold and throttle body. I'm getting air flow readings over 60% on my s-afc without being dyno tuned yet. Its a very healthy breathing motor and was running so lean before adding the s-afc I had to bump the fuel pressure up to keep it in stoich at 3K doing 80mph.

I'm very concerned with the fuel system being maxed out on the gsl-se with these same mods being done on his car.

peejay

It measures how much air enters the engine with the airflow meter, injects a certain ratio of fuel, and that's about it. No worries. I even think it's analog.

Many EFI systems can and do handle modified engines very nicely. Speed-density systems (they do not use an AFM or a MAF) get screwed up by altering the engine in any way. Some modern MAF systems also get screwed up because the calculate engine load and choose a certain A/F ratio and ignition timing based on that.

The GSL-SE's system isn't like that. It's old-tech, simple-as-an-anvil electronics, and the emissions requirements back then were still loose enough that the engine controls didn't have to be super precise.

WackyRotary

a s-afc is at best a flimsy toy to tune a engine compared to a real upgraded fuel management system such as a Haltech or Motec. The price intically is high, but is always transferable to different cars in the future which makes it much more worthwhile.

Jimmy325i

Well, when you've spent a total of 1500 dollars on a car including the purchase price, its hard to justify another 1200 on a fuel management system. I know that the s-afc has its limitations and downfalls, but for less than 1/4 the cost of a stand alone fuel computer it works for what I need.

So now can we please get back to the matter at hand? I'm concerned about the 1st gen EFI system.

David88vert

The stock fuel system is fine for your streetport. It works fine for my streetport also.

Jimmy325i

Does your street port use a ported TII intermediate housing producing over 200rwhp? This is a 6 port motor that breaths nearly as well as a bridgeport.

OK, I want to hear that the stock FI system can handle a bridgeport. The ports in my engines make mazdatrix ones look tiny....

Directfreak

iTrader: (2)

My previous Streetported SE had about 210 Flywheel HP using the stock analog FI system. I think it was limited by the MAF flap, and the 2 injectors. If I wouldve gone carbed, I probably could have freed up another 10-15 HP. After reviewing in hindsight, I think I was close to 100% duty cycle on the two 720cc injectors. Not a good thing.

If you're gonna run that close to the ragged edge, make sure you get a better fuel pump and increase the fuel pressure.

Jimmy325i

Cool. Thank you Drectfreak! Thats what I needed to know. I was thinking bigger injectors and bumping the fuel pressure. My buddy doesn't want to go back to carbs, so we're limited to either spending a mint on FI or making this system work.

peejay

Note that if you go with bigger injectors or increased fuel pressure, you'll need that s-afc or some other method of leaning it out, otherwise you'll be overrich everywhere.

If Directfreak's right and about 200hp is the limit of the AFM flap, then there's no point to bigger injectors. You don't need more fuel when you can't get more air.

Redwood

A hell, if you're so worried about it, drop the $700 or so and get a Microctech system. I have it on my FI 13B and it works great. Simple as hell to install, too. It can also run off the base maps for as long as you're n/a. Very nice system.

rotarygod

iTrader: (1)

I have a streetported GSL-SE and it runs pretty good. Needs more fuel on the top end though. Pulls great through the low-midrange but starts to taper off on the top end. Shifting after 7K is pointless. My '88 n/a pulled harder towards redline and it wasn't ported but it did have more fuel up there. You definitely need more fuel up higher than what the stock system can provide. I'm trying to figure out exactly how much power I can extract from the stock efi system but I'm only estimating around 200 fwhp or so. The stock afm is only 4 square inches so it is a big problem. The s-afc would probably help a little bit but a fuel computer that removes the afm would be better.

Jimmy325i

Yeah, if it was up to me (since its not my money) I'd make him get a motec or wolf or something and start fresh, but he's already sunk a lot more cash into this car than he wanted to. (some other guy screwed him on the last motor swap and charged him crazy money to fix mistakes the guy made the first time around on the clock) So I want to be dead sure that we're not going to be creating a monster that can't breathe. He claims he'll be happy with another 50whp, but i don't like under building engines that can make the 200whp #'s and still get 26mph. Just doesn't make sense to me to make a motor weaker than it could be considering it'll still be fuel efficient.

If I've come off like an ******* to anyone, I appologize. This is a mechanically inept older guy (60) and I don't want to make promises that he has trouble understanding why they couldn't be kept. Another mutual friend is trying to get him to go for the Wolf 3D system. If he'll spring for that, then I'll have no problems getting him tuned enough for the trip to the dyno. I'm just not sure he wants another 2K in parts this time around.

Also, S-AFC's cannot be used on the 1st gen ECU. Ghetto rigging or 1st class engine management are the only two options for fuel control.

P.S. My motor pulls hard all the way to 8135rpm when either the computer shuts it down or the fuel runs dry. (don't know which is happening yet) I was building for a 9500rpm or so rev limit, but haven't managed to get there at this time.

David88vert

Who told you that misinformation? The S-AFC will most certainly work on the GSL-SE stock ECU.

A better solution is to use a standalone though. MegaSquirt is probably the option that you will want to look at. It eliminates the AFM and saves a lot of money. You don't NEED a computer to control timing, although you may WANT it.

Directfreak

iTrader: (2)

Sorry David, The GSL-SE ECU is analog, just like the 12ATurbo in Japan. the S-AFC will not work with it. There are no "Chips" for SE's.

I do agree with you though, a Megasquirt is cheap alternative (Less than $200 I heard) and I was abount to recommend it. It should definately be used to avoid the crappy MAF in the first place.

fatboy7

I've heard with flap MAFs you can get larger injectors, and put a stiffer spring on the flap, so the ecu thinks its getting less air than it really is, shortening the pulses. So that it isn't over rich, and it increase the max capacity of the flap. That would be a getto rigging for sure, though.

David88vert

Do explain please, the AFM send the stock ECU a signal. The S-AFC breaks that signal and alters it and sends the modified signal to the ECU. Why wouldn't this work on the GSL-SE? I have done this many times on 2nd gens, and am very familiar with the wiring of the GSL-SE ECU. It will work from a wiring standpoint. Is there something in the programming of the GSL-SE ECU that is different, if so, exactly what? And where might I find documentation on this. I have the FSM and do not see anything about it in there.

Directfreak

iTrader: (2)

Hey, I am just repeating what Crispeed told me. The analog signal cannot be altered same way. Think of it as almost mechanical and you'll understand, that the software can't really cheat the system. It's too primitive to do what you want it to do with the S-AFC.

Again, even with an S-AFC, you would need more fuel/more injectors. IF you want a simple solution to get more fuel, keep the MAF flapper door partially open, and it will always add more fuel across most of the powerband. Again - you ar elimited by injectors and duty cycles.

David88vert

I see what you are saying, but I don't think you understand how the afm and the ecu work together. I have looked at the circuit quite closely, and I cannot see any reason why it would not work. I will let you know in the next couple of days with 100% certainty. The circuit is almost 100% identical to the 86 N/A ECU - and I know that works with the S-AFC.

BTW - I have larger injectors already.

Opening the AFM flapper door is a bad idea, you decrease it's range of movement. This gives tooo much fuel when you are at idle, possibly causing flooding if your idle dipped too low. Of course, if you idle at 3K rpm (BP), that's probably not a problem. :-)

Jimmy325i

Analog = varied voltage based on amount of pull on flapper.

Digital = varried pulsewidth based on same mechanical actuation.

S-AFC's aren't listed as being usable with 1st gens for that exact reason.

Tell me more about the megasquirt. Is this an analog device? I've never heard of it

Directfreak

iTrader: (2)

Megasquirt.

Jimmy325i

Ah, I was thinking it was just to replace the MAF... not a full computer.