Bruceman

iTrader: (5)

I have an '82 GS with 12A and Racing Beat Dellorto setup. I have been tooling around for the past 6 months with fuel injecting this before installing a turbo from a TII. The injection system is a Bosch K-jetronic from an '84 Audi 5000 Turbo. Don't ask why... it's just a fun thing to do.
Anyway I have it running with the fuel injection installed. Using a 13B upper manifold and throttle body on top of the RB lower manifold.
It's not fully sorted yet - the fuel mixtures need some more tuning.
I have noticed an incredible increase in the torque at low rpm's. This thing now accelerates like crazy whereas with the Dellorto it would have very little below 2500-3000rpm. Now I would have to be very carefull on wet slippery roads.
I don't know about the top end power although I assume if there is lots more down low then its probably weak up top. I think the turbo should fix that though.

Why do you think it has so much more bottom end power?

Directfreak

iTrader: (2)

RB 12A Lower manfold with GSL-SE upper?

Aren't the RB 12A Manifolds only for Holleys (4 barrel Openings)



and for Webers / Dellortos (2 Barrel openings)



So if the stock GSL-SE (or any other F.I. 13B) has four runners on the upper and lower manifolds


Then how did you get them to mate up?

2 need 2, 4 needs 4, etc.

Or am I missing something altogether? I really got confused on this one..

peejay

That is sweet! I was always tooling around with the idea of putting K-Jet on a rotary. Glad to see I'm not alone, AND that it works

I see how you did it. The Dell' setup is designed with a 2-piece manifold - the upper mates with a GSL-SE lower manifold, and they make a 12A lower manifold that will mate with that. So you could bolt a GSL-SE upper manifold on a 12A Dell' lower manifold. Neat.

Another thing you could do is put GSL-SE fuel injection on a 12A, by putting a GSL-SE center plate in a 12A for the injecor bungs, and of course the Dell' lower manifold to mate with the GSL-SE upper. That's actually something i've been wanting to try, too

Bruceman

iTrader: (5)

Direct freak

The RB Dellorto consists of an upper and lower manifold.
Both need to be used on a 12A while for a 13B just the upper is needed because it bolts up to the original 13B lower manifold.
Therefore the lower 12A RB Dellorto manifold matches the 13B stock fuel injection upper manifold.

It took me a while to figure that out to.

moremazda

iTrader: (4)

So what is special about K-jet FI? I have only heard about it. I have never heard an explanation on it though.

Ryan

setzep

Isn't that mechanical FI?

Directfreak

iTrader: (2)

Thanks. I understand it now. I used to have a Dellorto 13B setup on my old 81 GSL, and got confused. I haven't even seen a 12A in years...

Well, for all those people who want to make a Fuel Injected 12A setup, this sound like a good Idea.
Just add a few of injector bungs to the runners and you're there. Less hassle than trying to use a GSL-SE center plate too.

peejay

K-jet directly measures air and uses this measurement to alter fuel pressure to the injectors. The injectors are constantly flowing (the K stands for Kontinuerlich, if I'm not mistaken - continually).

I just think it's a neat system. Simple and bulletproof.

What many people don't know is that this system which was used up until very recently on Mercedes, Porsches, and earlier on BMW and Volkswagen, is all based on the Rochester fuel injection system. (Think '57 Chevy and Corvette) Bosch bought the rights to it and developed it into K-jet.

edit: my keyboard is going flakey, keeps dropping letters While I'm editing, it's no hassle to put a GSL-SE center plate in to an engine... my logic is, why bother going with fuel injection unless you've got a modified engine? So when you're building the engine up, just use a GSL-SE center plate instead of a 12A unit and you're in business

Bruceman

iTrader: (5)

It is cheap - full system with injectors, fuel lines, air sensor, fuel distributor....for $50 on ebay.

It is simple to tune. Fuel mixture is determined by the responce of the air flow sensor and engine temp + manifold pressure.

Oh and it is cheap.

Not necessarily easy to install. Lots of fabrication required to hold injectors etc.

Would I rather have a Haltech? Hell yeah but I'd have to go without beer for 2 years to buy one.

Mr. ImportGuy

This is kind of off topic but can that heat sheild be used on a 12a, with racing beat headers and a stock intake manifold?

peejay

They are trivial to fabricate... it's just a piece of metal with four bends in it so it doesn't flop all over the place, and a couple holes drilled into it to attach to the top header studs.

I don't think you'll notice much difference, but it does help keep gasoline from dripping on hot headers.

Mr. ImportGuy

Ya I could make one at the shop I work at lol. See what work does to you it makes you not able to think when you get home haha.

diabolical1

iTrader: (3)

well, first off ... congratulations!!!!! i tip my hat to you for figuring that one out. for all the years i was running 12A's and wanted to get fuel injection for it, i NEVER thought about that one. it pisses me off now because, back then i could actually have gotten a lower Dell'Orto 12A manifold ... now i would imagine getting one is like getting "real" Cuban cigars!

but seriously, man, that sounds like a sweet setup! sounds like a lot of fun!

about the bottom end issue. i will hazard a guess! i think the longer runners of the upper RE-EGI manifold are responsible for it!



peejay ~
kontinuerlich???? your knowledge really SCARES me sometimes!

Manntis

I had an Audi Coupé for a while, and that K-jet system was elegant in it's simplicity. Then again, SOOO many things on that car were like that. My only beef was that Germans tend to use wire gauges that can just barely handle the current, and fried fuseboxes were frequent on them.

you know how strut tower bars stop excess engine bay flex? Audi extended the top of the firewall out to connect just behind the strut towers.

You know how rack & pinion steering often means the engine is elevated so the steerong rack can sit beneath it? Audi put the rack OVER the engine/tranny.

If VAG (Volkswagen Audi Gruppen) ever teams up with Mazda ew'd see the world's best cars, bar none.

peejay

That top-mounted rack is garbage IMO... it means the steering forces have to be transmitted through the strut tube before it gets to the knuckle - there's a fair bit of flex at the strut/knuckle joining. Also any looseness in the strut shaft or in the upper strut mount will be felt in the steering wheel as looseness, and the steering focred being fed up that high will CAUSE the struts and the mounts to fail more rapidly. And let's not forget that the adjustment is a complete pain in the *** because it's way up high where you can't reach it when you're crawling around under the alignment rack.

But I'm not BIASED or anything....

(call me crazy but if I had any VW it'd be a VW Fox with a Quantum close-ratio 5-speed trans, and either a crossflow 8v head or a 1.8l 16v engine swap... I'd just have someone else do my alignments )

ObRotary: NSU rushed their Wankel to market to have a production Wankel-powered car before Mazda, in order to get licensing rights. The NSU engines turned out to be rather unreliable, and they turned back to new boingers to build more profits. The VW/Audi engine was the last engine designed by NSU before they were bought. That engine has basically been unchanged from the '75 Dasher right up to the modern 20v engines.

So just think... if Mazda wasn't so good, VW would have been screwed with no decent watercooled engine and declining interest in their aircooled stuff. Because of Mazda, NSU made the engine that kept VW/Audi alive!

Manntis

VAG had a ton of European options, but Mazda's impending purchase undoubtedly helped.

The upper steering is very reliable. The Canadian Armed Forces even use a VW/Audi Iltis (kinda like a jeep) and that steering can take a beating that bottom-mounted racks can't.

In addition, by mounting the rack high up there's 2 frame rails front to rear that expand where the transaxle shafts emerge, and have a hole through 'em for the half-shafts to poke through. No hanging diff or t-case, just frame rails to protect all the moving bits.

but I'm getting way off topic.

BTW: Congrats on the swap! Amazing work, and kudos to you for your ingenuity

j9fd3s

iTrader: (3)

i hate the way the tension the timing belt on the 5 cylinder, wtf is that. mazda would have made a sealed pump so it didn't have to slide on the gasket. and i liked the bonus radiator for the #5 cylinder too.

congrats on the fi 12a, i was thinking about doing that with the r100, but webers are sexier. i've been curious about a setup like that for years

mike

WackyRotary

I also had an idea to get more out of a '84-85 13b. Do this: Use front and endplates from a 12a and extend port them, using the 13b centerplate and use a lower Delarto manifold for a '70's 4port 13b(if such one exsists)and hook that to the upper GSL-SE manifold? Would that work? I'd REALLY like to know so I can recommend this possible mod to someone when we rebuild it.

I'm aware that by doing this, some lowend would be lost, but some highend gains would be made also. I'm not suggusting bridgeporting the front and rear endplates though since I have no clue if the stock computer/injectors could even handle it.

j9fd3s

iTrader: (3)

it would work, but i think the stock se injection is too restrictive to see big gains. you might see big gains on a 12a though. who knows though i could be wrong, and it would run nicely

mike

peejay

You can actually get more high RPM power from the 6-port endplates than with the 4-port!

Dave Lemon from Mazdatrix detailed this a while back in the 2nd-gen forum. They were having problems getting the power peak on their '91 E/Production engine (6-port 14B street ported) DOWN BELOW 10,000rpm. Power would just keep climbing the higher they revved it.

I'd sure like to have problems like those

WackyRotary

I am wondering what the conditions for this were to determine this. What did they do to the ports and what the heck is a 14b? With all things being equal, there is some discrimpency on how that occurs they make more above 10000rpm? From normally asperated?

I'm thinking a potential 4port 13b using 12a endplates '84-85 setup has been done before sometime to make a bridgeport '84-85 13b with a aftermarket EFI computer. Also it makes sense using 12a endplates should have more flow then stock 6port endplates with porting? Why would a 4port based on 12a endplates on '84-85 13b make less power? It seems that the endplates with 6port design would flow less stock and is designed better for 2500-4000rpm operation. I was meaning high rpm as(4000-8500rpm)operation with endplates from a 12a extendported.

diabolical1

iTrader: (3)

i'm guessing he just missed the "3" key ...


again, i'm only guessing ... but, it probably all comes down to sheer volume. when all 6 ports are open, it will suck in a whole lot more than the ports outer ports of a 12A housing. it would only take some reshaping and i'm sure the 5/6 ports will essentially provide more than a ported 12A housing used in a 13B application ...

peejay

The stock 6-port end plates have a closing time as high as a rather large street port! (I think they close at 70degATDC, most 4-port street ports close at 50-60degATDC)

I think I know what they did... they didn't say exactly, but I'm guessing they used a T2 center plate and streetported the crap out of it, or at least used a lot of JB-Weld on a stock 6-port center plate to get the closing time up high enough, and then ported the crap out of the end plates.

And yes, I mis-typed 13B.