Use AAN injectors on a 3B? What FPR

[chris miller]

I'm doing a conversion to a coupe originally fitted with a 7A 20v motor, using a 3B motor. I've also got a set of lower mileage AAN injectors that I'd like to consider using on the 3B.

Anyone done this or similar? I've got two ECUs, stock and a chipped (IA Stage 3+) on a mostly stock car otherwise. I'll also have the stock 7A Fuel Pressure Regulator (FPR). The 3B uses a 3 bar FPR, the AAN a 4 bar FPR, and I'm not certain of the 7A (4.2 bar?). If it is 4.2 bar, I'd think the ECU could compensate for the slightly increased fuel flow using fuel trim.

I've also got the AAN intake and might consider replacing the 3B inlet as the intake path is shorter, but the radiator is in the way. Not sure if I can safely lower the radiator far enough...

Thanks for any BTDT.

[Josh-stateside]

if you use the aby injectors at least 4 bar is a must because the aby injectors would be running lean at 3bar.

Some things to consider about the aan intake:

I believe it hits the power steering pump if I remember right. I believe the 3b water manifold would also hit the aan throttle body? So you would need an aan water manifold too. Which also complicates the issuse because now there is very little room for the hoses with the powersteering pump if you choose to do an aan intake on the cheap. There is some pics around and alot of information on both of these issuses, injectors and manifolds.

If you want to go into details:

Search for doug's and mark halligans custom aan intake manifolds aka "projects"
Search for "injectors cc" or something along those lines.

There is a coupe of coupe with aan intake manifolds and severly angled back radiators but if I remember right they ditched the stock fan setup.

P.S. I told Richard you would be interested in a windshield. I picked mine up today. I padded the bed of my ranger and drove home with no issuses.

Cheers
Josh

[porkkis]

Usually AAN/ABY injectors are used at higher pressure, but if you go with the 3b FPR you should have no problems as the flow in AAN/ABY and 3B injectors is about the same at 3 bar (within few %).
Motronic will handle the tiny difference without problems. When the engine is first time run and you check the fault codes a code for mixture adaptation limit will appear if the Motronic can't handle the difference. In this case I would go for an adjustable FPR. A good investmentfor future needs.

[porkkis]

And about the rad fitment. My friend put an AAN IM to his t89 conversion.

Pics: http://s90.5cyl.net/gallery/2_17

It's a tight fit and don't even dream about it with aircon.

[Josh-stateside]

Usually AAN/ABY injectors are used at higher pressure, but if you go with the 3b FPR you should have no problems as the flow in AAN/ABY and 3B injectors is about the same at 3 bar (within few %).
Motronic will handle the tiny difference without problems. When the engine is first time run and you check the fault codes a code for mixture adaptation limit will appear if the Motronic can't handle the difference. In this case I would go for an adjustable FPR. A good investmentfor future needs.

Pokkis.. that is wrong. Aby/aan injectors at 4bar is 320cc. If he would run these at 3bar he would be less than 320cc/min and have a permanent lean condition. The only way he can use aan/aby injectors is to use the 7a fuel pressure regulator.

[Josh-stateside]

Pokkis.. that is wrong. Aby/aan injectors at 4bar is 320cc. If he would run these at 3bar he would be less than 320cc/min and have a permanent lean condition. The only way he can use aan/aby injectors is to use the 7a fuel pressure regulator.

http://www.s2forum.com/forum/showthr...light=injector

[Erikb]

Yep you are right josh, I fitted some aby injectors in my car. The car didnt drive that well, it started but was running lean. The 3b injectors have the right flow at 3bar, the aby/aan injectors uses 4 bar to flow the same amount.

If i where you chris I would bring my 3b injectors to a place where they can be ultrasoon cleaned, I did it. The car really transformed.

[chris miller]

Thanks. I've already got the AAN injectors, and I've only got 4 good 3B injectors (one was borrowed and never returned). I may look at trying the 7A regulator to start. I'd think .2 bar of fuel pressure (about 3psi) could be controlled with the fuel trim.

[porkkis]

Ok, sorry.

[Mihnea]

Chris,

You can use the 7A FPR with the AAN injectors, this should give you close to the stock 3B injectors rating...

HTH,

Mihnea

[S2central.net]

Agree with Mihnea & Josh on this one.

Paul

[audiman]

Same here

[porkkis]

I've heard that here in Finland is atleast one 3B with ABY injectors and it works fine. Perhaps the adaptation is "on the edge" then so in some cases it works and in some not.