SAFC II Help - 370cc's on a non-turbo KA

[Lurkable]

I have 370cc sr injectors in my non-turbo motor. To adjust fuel to stock as if I was using 270cc's, I know the settings should be -27% for all RPMs. My question is, should the actual settings on the AFC be - or +?
I've been having troubles with my motor, and in it's current state, it runs crappy as hell at -27%, much better at 0%, and even better at +50%.

I'm afraid to test drive the car before I get the settings right, because it's a brand new motor and I want to know things are straight before I break it in. Another point of interest - the motor has 8.5:1 pistons because I was planning on turboing it. This effectively increases displacement, does it not? And if so, I assume, wether the settings should be + or -, they should also be greater than or less than +/-27%.

Can anyone offer me any advice on this? I'd really appreciate it, thanks!

Sorry, I know there's alot of information out there about the SAFC but I feel like I've read it all before. I learned alot first, and I was positive that I understood what I was doing by the time I went to install the unit in my harness.
I do know 100% that the I installed the SAFC correctly, it's been checked by multiple people. (The instructions are pretty easy to understand anyway).

I just feel kinda at a loss here. I can only hope that someone here has had similar problems. I'm going to visit my car tomorrow night to hopefully hook up some smog equipment and see just how dirty rich it's running. Any information I could take with me would be greatly appreciated. Again, thanks in advance for any help!

[orion::S14]

1) Displacement has nothing to do with S-AFC tuning...it doesn't care how much air the MAF is moving, it will make corrections no matter the value. Plus, the difference in 8.5 and 9.5 will add so little displacement it's negligible.

2) What in/out are you using?

3) What MAF?

4) Are you SURE there are no vac leaks?

5) Are the injector O-rings OK???

??? - Brian

[tre]

throw the stock injectors back in and fire it up

[tiresmokes13]

no neeed for bigger injectors..take them off

[rollhard]

Originally Posted by Lurkable

I have 370cc sr injectors in my non-turbo motor. To adjust fuel to stock as if I was using 270cc's, I know the settings should be -27% for all RPMs. My question is, should the actual settings on the AFC be - or +?
I've been having troubles with my motor, and in it's current state, it runs crappy as hell at -27%, much better at 0%, and even better at +50%.

I'm afraid to test drive the car before I get the settings right, because it's a brand new motor and I want to know things are straight before I break it in. Another point of interest - the motor has 8.5:1 pistons because I was planning on turboing it. This effectively increases displacement, does it not? And if so, I assume, wether the settings should be + or -, they should also be greater than or less than +/-27%.

Can anyone offer me any advice on this? I'd really appreciate it, thanks!

Sorry, I know there's alot of information out there about the SAFC but I feel like I've read it all before. I learned alot first, and I was positive that I understood what I was doing by the time I went to install the unit in my harness.
I do know 100% that the I installed the SAFC correctly, it's been checked by multiple people. (The instructions are pretty easy to understand anyway).

I just feel kinda at a loss here. I can only hope that someone here has had similar problems. I'm going to visit my car tomorrow night to hopefully hook up some smog equipment and see just how dirty rich it's running. Any information I could take with me would be greatly appreciated. Again, thanks in advance for any help!

Hi Lurk,

I will try to help you the best I can. Dont take anything personally if I point out any mistakes you have made.

First of all, youre going about this the wrong way. Normally aspirated at a compression of 8.5:1 and large injectors like that...your car is going to run like complete crap...assuming it will run at all. I really question the mechanic that is doing the work for you as he should know this.
The compression of the motor does not effect the displacement of the engine itself at all. You can have a 2.0 motor go from 11.5:1 compression to 8.5:1. All that has changed was compression and not displacement. Its still a 2.0L.
Tuning NEEDS to be done on the dyno with a wideband. Simply saying -27% is not going to cut it because you have no idea how rich or lean you are running... In this case, youre running piss rich. So rich that I can see your car hardly idling and hesitating as soon as you give it gas. If you plan to turbo the motor, you should really do it at the same time. A motor with that low of compression will rely on the boost to give it the power it needs. Without the boost pressure, its going to be a dog. Im talking less tq than a b16 engine. The best thing you can do now is to get the turbo on there and take it to a real shop that knows what they are doing. Any mechanic that will install that stuff for you and let you drive off is not worth a penny. You would be surprised at how many of our customers are other shops who completely F'd up their customers cars. If you want to drive the car as it is right now, swap the stock injectors back in and leave the afc settings at "0". The injectors are easy to install so you can do that when you are ready to turbo the car. Dont expect it to run like your stock KA though since your compression is so low now.

[tre]

It does affect displacement maybe like 5ccs :P
why does everyone say normally aspirated instaled of naturally aspirated? lol

[sunnys14]

Originally Posted by rollhard

Hi Lurk,

I will try to help you the best I can. Dont take anything personally if I point out any mistakes you have made.

First of all, youre going about this the wrong way. Normally aspirated at a compression of 8.5:1 and large injectors like that...your car is going to run like complete crap...assuming it will run at all. I really question the mechanic that is doing the work for you as he should know this.
The compression of the motor does not effect the displacement of the engine itself at all. You can have a 2.0 motor go from 11.5:1 compression to 8.5:1. All that has changed was compression and not displacement. Its still a 2.0L.
Tuning NEEDS to be done on the dyno with a wideband. Simply saying -27% is not going to cut it because you have no idea how rich or lean you are running... In this case, youre running piss rich. So rich that I can see your car hardly idling and hesitating as soon as you give it gas. If you plan to turbo the motor, you should really do it at the same time. A motor with that low of compression will rely on the boost to give it the power it needs. Without the boost pressure, its going to be a dog. Im talking less tq than a b16 engine. The best thing you can do now is to get the turbo on there and take it to a real shop that knows what they are doing. Any mechanic that will install that stuff for you and let you drive off is not worth a penny. You would be surprised at how many of our customers are other shops who completely F'd up their customers cars. If you want to drive the car as it is right now, swap the stock injectors back in and leave the afc settings at "0". The injectors are easy to install so you can do that when you are ready to turbo the car. Dont expect it to run like your stock KA though since your compression is so low now.

ummm... heres somethings u should think about.

#1 making the safc run -27% across on 370cc injectors threoretically should make them run like 270cc's (do the math). i ran 480cc injectors + safc2 and i set it to -44% across while NA and it was fine. (my wideband even said so)

#2 running 8:5 compression NA isnt that bad. i ran 9:1 compression while breaking in my motor with 480cc's + safc2 + z32 maf and it felt like stock. only .5 compression difference between mines and his. 1 compression point drop from 9.5:1 to 8.5:1 would be like what, at the most, 10 hp?

#3 having less torque than a b16 while a lil lower compression? i was still able to take off on my bro's vr6 jetta with my "lower compression" pistons + "larger injectors"

[Lurkable]

Thanks for the replies. Actually, the reason I'm hesitant to put the stock injectors back in is because they're dirty as hell. The screens are practically solid black, which is part of the reason I installed the 370's, as I planned on installing an sr t25 turbo eventually. I guess I could still try it though...

I actually have the turbo and all the piping and stuff I'll need. I've had it for quite some time now, but I was worried about installing it before properly breaking in the motor.

[tre]

go get them cleaned. i dunno pricing but i'm sure its cheap

[BigVinnie]

1st problem is spray pattern and effect. It will spray nothing like the 270cc injectors did no matter what the pulse width is. It won't atomize your air and fuel properlly.
2nd stock compression isn't high enough to crunch enough air for the type of ratio you are looking for.
3rd I'm betting that timing is advanced which will throw off the ignition timing and fuel maps you probably need to lean out more than -27 IMO, stock tune increases richness (HC) the hotter cylinder temps become with advanced timing.
4th why are you even attempting it without a wideband o2, not smart IMO.
5th reason using a stock KA maf and stock ecu tune is getting you no where.

[thejester03]

Ok, just one quick thing, the difference between high and low comp pistons in the shape of the surface of the piston right? If the Bore and stroke are the same as before, you will have the same displacement. But with lower comp. you will have a slightly larger combustion area, not displacement, correct?

[kuramaya]

Some great info ^ up there. Wideband, Wideband, Wideband. I run one all day long, it is the ultimate insurance.

[orion::S14]

Originally Posted by thejester03

Ok, just one quick thing, the difference between high and low comp pistons in the shape of the surface of the piston right? If the Bore and stroke are the same as before, you will have the same displacement. But with lower comp. you will have a slightly larger combustion area, not displacement, correct?

Yes, but for pretty much any forged piston...you'll need to bore/hone the motor.

So even if you go the minimum of .020 over (89.5mm pistons)...you're going to get a slight bump in displacement.

- Brian

[BigVinnie]

Originally Posted by thejester03

But with lower comp. you will have a slightly larger combustion area, not displacement, correct?

Assuming that you mean a lowered dish to increase combustion area.
Increasing the combustion area such as lower CR at 8.5:1 means that the energy output is less than optimal for stock 9.5:1. This means in order to make enough energy that is more effecient to the A/R ratio, fuel would have to be less than if it were at 9.5:1 (more lean than usual), just due to the fact that 8.5:1 compression will compress less air with a much larger combustion area. I don't understand how -27% was calculated to use on a 8.5:1 CR?
8.5:1 is a horrible atomizer for NA, but works great for FI.
Only reason why it works so good on FI is because when air is forced inducted it is already being compressed into the surface area, and is more controlled to too much air being compressed in the combustion stroke. Much safer to use and it uses less fuel to cool the cylinder charge from detonation than what would need to be done with 9.0:1 CR or higher.