Evil Talon- 16g 650cc knob AFC

[BC91AWDTalon]

Took it to the track, untuned and on base timing, with 110 octane mix on 93 octane gas. The car felt pretty good, it sucked we snapped the back axle in the rear at the end of the night, so that ride home was fun. The best run we could get off was a 13.3 @ 100, but that run would of been a lot better if I hadn't lit the limiter up in 3rd gear. It's kind of tough looking at the A/F guage in the ashtray, and trying to drive. Anywho, the 60 was real good, came out real steady on those blown struts - 1.78. The eight mile time dropped too by 3 tenths, but then I lit the limiter up in 3rd. So thats what held me back.

I noticed that the A/F guage was running reallllll rich at the top of the gear. I pulled fuel for the next run, but then when the owner of the car launched it, he snapped the back axle....novice driver, popped the clutch.

I want to know, anyone that uses the knob style AFC and if they can give me help on tuning it and where to start out, and what to look for.

Besides that the car also feel like it isnt advancing as much as it could. The motor doesnt make more and more power is it goes through the power band. It kind of feels steady. Is that because of the base timing? Should I have it advanced more? It is a pretty decent setup and rather sturdy, w/ compression reading 180-185 across the board.

So any tuning advice would help. Thanks in advance.

 

[xcelr8n]

Its an AF gauge or a AF ratio gauge from a wideband o2?
If its just an A/F gauge stop watching it so much, its useless anyways.

 

[GILZTSIAWD]

Its an AF gauge or a AF ratio gauge from a wideband o2?
If its just an A/F gauge stop watching it so much, its useless anyways.

Agreed. If you get that gauge out of the rich area and get it to "stoich" you will actually be way too lean and be getting some knock and pulling timing, which may be the reason it doesn't feel like it is making more power now. You really need to get a logger if you are going to be tuning with that afc. Atleast get a wideband, but a logger would really be a better investment in this case.

 

[CanadianTSi]

7500 is way to late to shift with a 16g...shift at 7k.

 

[xcelr8n]

Even 7000 is to late to shift IMO, Look at dyno sheets of 16gs with stock or close to stock engines, similar to youre setup, power drops drastically after 6500 rpms.

 

[NewB2dsm]

Even 7000 is to late to shift IMO, Look at dyno sheets of 16gs with stock or close to stock engines, similar to youre setup, power drops drastically after 6500 rpms.

7000k is not to late to shift, you are going to make peak power on a 16g around 6grand. And it really doesnt drop off to fast from there, Granted it does but not a huge amount. If you shift sooner you will fall way below peak power, You want to come back into your power band asap. I shift my car at different rpm in each gear, 1st i take to 7500, 2nd a little over 7k, and 3rd to 7k and 4th the rest of the track. But its really trial and error on each car, i found this work pretty well on my car so thats what i do.

 

[GILZTSIAWD]

Is your hp updated since that time you ran? If not that is a darn good time for that power!

 

[BC91AWDTalon]

Well, I don't think the guage is COMPLETELY USELESS. I know its not too accurate, but it still reads rich and lean conditions on the o2 sensor and from there you can base the tuning. It's better than nothing. I stated I needed a logger to see what type of timing is being pulled and type of knock I am getting. And, I didnt say I shifted at 7000rpm, I actually shift more around 5500. The car makes way more pulling power at a 5500rpm shift to 4th than at anything over 6000rpm. I already know I need an EGT guage and a logger, but I was just asking if I could get any TECHNIQUES on tuning this 5 knob style AFC.

 

[xcelr8n]

7000k is not to late to shift, you are going to make peak power on a 16g around 6grand. And it really doesnt drop off to fast from there, Granted it does but not a huge amount. If you shift sooner you will fall way below peak power, You want to come back into your power band asap. I shift my car at different rpm in each gear, 1st i take to 7500, 2nd a little over 7k, and 3rd to 7k and 4th the rest of the track. But its really trial and error on each car, i found this work pretty well on my car so thats what i do.

It's my opinion that you are wrong, on a stock cammed dsm, with a 16g, you will make very little power beyond 65--rpms, and times wont be any better if you shift at redline compared to mid 6000's range. The only gear I can see takin that far is 1st since it spikes so quickly anyways.

 

[NewB2dsm]

It's my opinion that you are wrong, on a stock cammed dsm, with a 16g, you will make very little power beyond 65--rpms, and times wont be any better if you shift at redline compared to mid 6000's range. The only gear I can see takin that far is 1st since it spikes so quickly anyways.

Thats fine, and i will agree there is little power above 6500 but here is a old dyno chart of my car on stock cams. Peak power is 6grand again, and the power lost above that is shown but you want to come back into the mid peak powerband, that is how you determine when to shift.

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And there is a correction factor for the dyno dynamics dyno. Its about 17% so my numbers come closer to 338awhp./

 

[prophecy7115]

on a complete stock dsm with a 16g, and mbc, what can you run on about 16psi?

 

[GILZTSIAWD]

on a complete stock dsm with a 16g, and mbc, what can you run on about 16psi?

You can almost make it to the end of the bench....

 

[prophecy7115]

bench whats that?

 

[hybridshooter]

it's what your racing on!

go to a track and find out what it will run. Bench racing means nothing because every car is different, no two setups are identical.

 

[prophecy7115]

thanks.

 

[4pistons]

I was just asking if I could get any TECHNIQUES on tuning this 5 knob style AFC

I've had one for years. The technique you'll need to learn is a gentle twisting motion to change the position of the knob!

Seriously... If there is ANY technique to tuning ANYTHING it's you must have DATA and know what it means. You can't just say "the car also feels like it isnt advancing as much as it could". How on earth would you know without actual data? You're guessing. It could be knocking, boost leaking, maxing injectors, overrunning the MAF, cam timing off... etc.

Guessing is not tuning. You have to know, and you can only know with information.

Rick - '91 GSX

 

[NJdsmguru]

hey allen....i see ## having probs w/650cc injectors and tuning.i would put a 2g mas,maft,or eprom ecu w/chip compensated for 650cc.

 

[BC91AWDTalon]

AIGHT THANKS GUYS...

im in the process of buying a datalogger and a fpr beacause my 255 fuel pump is overriding my stock regulator and its running rich so i cant tune it good enough..im also getting an egt guage and then i should be able to tune it a hell of alot better..

also i never thought it would be so hard to find a rear axle since i snapped it...

now does anyone know if i take the other rear axle out if i can use a long extension to know out the peice stuck in the other side...

 

[NJdsmguru]

yeah you are overrunning your stock fp regulator...BUT being though you 650cc injectors and an afc.....you're decreasing your airflow signal to the ecu too much which gives you high timing advance=no power .......buy an eprom ecu and a keydiver chip compensted for 650cc and be done with it.

 

[NJdsmguru]

Oh yeah i have a stock 3 bolt rear for sale if you need one?

 

[titogs95]

Not a bad time!
BTW what numbers do you have in the Safc?
I am trying to compare with mine, a backgroud Idea. I am trying to get a hold of a WIDEBAND and finnaly tune the car. I am impatient.
and getting the 2G mas is a idea.

 

[BC91AWDTalon]

i have the knobs turned down about 3/8 of the way on the last 3 knobs and about 1/8 on the 1st and 2nd....

its not a afc digital its a 5 knob style...

 

[4pistons]

Here's where my AFC was set when AMS adjusted it on their dyno a year and a half ago using a wideband, staying on the safe side and putting down 255 whp at 16 psi. My mods are basically the same as listed in my profile. Air temp was about 65 degrees.

800 (-6) 2400 (-4) 4000 (0) 5600 (-10) 7200 (-10)

Each tick mark on the AFC is 2.

This won't apply directly to your car with different mods so don't use it as the bible. You need to get a logger and find out what is going on with yours.

Rick - '91 GSX