Modded Mustang Forums banner

1 - 20 of 53 Posts

·
Registered
Joined
·
16,245 Posts
Discussion Starter · #1 ·
I am thinking of making this swap. My boost is at 9-10 #'s and my numbers are below. My tuner tunes my car really safe so im thinking i can make this pulley swap without another tune. Its not like im going from 3.60 to 3.00 size. Would it be ok as long as i watched my a/f guage under WOT or will it **** with my maf and ****?

for 35 bucks i can get the 3.00 pulley. But would i actually notice the effect of the pulley swap without a tune?
 

·
Registered
Joined
·
4,366 Posts
you should be okay because the tune goes by how much air is being pushed into the engine so it should calculate the extra air from the smaller pulley and adjust fuel accordingly.. the only problem you might run in to is if you start to peg the fuel system or maf.. also if you put more air in the engine than it was tuned for your a/f might not be quite right at the highest rpm where you are experiencing more boost than before
 

·
Registered
Joined
·
16,245 Posts
Discussion Starter · #3 ·
yeah thats my thing... i am worried that there may be more air than what the tune calls for causing it to run lean. Nobody else have an opinion?
 

·
Procrastinator
Joined
·
4,558 Posts
or if anything watch the injectors/pump with a hand held tuner or whatever you go if you don't have a wideband. Wont show afr, but should show if you are closing in on maxing out your fuel system.
 

·
~C~, The Other White Meat!
Joined
·
1,623 Posts
Personally I would have it retuned or have them send you an email tune update for it.

On that note, if you do decide to do the swap, can I buy your 3.2 pulley for a good price? I want to move from a 3.6 to a 3.2.
 

·
Registered
Joined
·
2,363 Posts
i would get a new tune if you plan on upping the boost....that's just me.. :)
i'm pretty sure i have the 2.87 on my car..making about 15psi wihtout the ic 12.5 with....i want to go smaller we'll see in the spring..i want to squeeze more out of it without opening the motor up..
 

·
Banned
Joined
·
7,007 Posts
you should be okay because the tune goes by how much air is being pushed into the engine so it should calculate the extra air from the smaller pulley and adjust fuel accordingly.. the only problem you might run in to is if you start to peg the fuel system or maf.. also if you put more air in the engine than it was tuned for your a/f might not be quite right at the highest rpm where you are experiencing more boost than before
That's not true. I can't remember which way it goes (open loop or closed loop), but your car only runs off the MAF readings 1/2 the time. I think (and somebody correct me if i've got it backwards) that your car runs off the MAF during closed loop operation (idle and part throttle) and runs off of pre-loaded settings in the computer during open loop WOT operation.

That being said, if your tuner is really conservative, then he may have programmed the computer to run kinda rich during WOT, so you might be okay with a smaller pulley pushing more air.

What are your WOT a/f numbers?
 

·
Registered
Joined
·
399 Posts
I have swapped pulley and it has been ok. There is only like a 1-2 psi increase with each pulley size. If your a/f is lets say 11.3 you should be fine my car is 12.0
 

·
Registered
Joined
·
4,366 Posts
That's not true. I can't remember which way it goes (open loop or closed loop), but your car only runs off the MAF readings 1/2 the time.
It still runs off maf counts during WOT since this is the only way the computer knows how much air is coming in, open loop means that the factory o2 sensors aren't being used at that moment to adjust the fuel
 

·
BYAHHHH!
Joined
·
18,672 Posts
yeah you run a little rich when in open loop. Closed loop is operating tempture.
 

·
Baker Jr.
Joined
·
3,472 Posts
Personally I would have it retuned or have them send you an email tune update for it.

On that note, if you do decide to do the swap, can I buy your 3.2 pulley for a good price? I want to move from a 3.6 to a 3.2.
Im buying it bro sorry
 

·
Registered
Joined
·
16,245 Posts
Discussion Starter · #15 ·
i have a wideband. I might swap it out and run it and see what happens. If nothing else, i can always swap back to the 3.2 or just go get a tune.
 

·
Registered
Joined
·
16,245 Posts
Discussion Starter · #17 ·
plx digital one from Joe at trick tuners
 

·
Banned
Joined
·
7,007 Posts
Sorry I'm a dumbass, I was thinking MAF instead of 02s.

Baker, I say swap it and see how it runs. If it's too lean for your comfort swap back or get a new tune. If it runs fine, congrats on the added boost
 

·
Registered
Joined
·
16,245 Posts
Discussion Starter · #19 ·
lol... i have a factory dvd player out of my 07 harley f150 that im about to put on ebay and it should go for a lil over 200 bucks shipped so i might use that for my tune if not. The bride to be just doesnt want me fooling with the stang while we get into the house. Good thing she is there to keep me straight!
 

·
Registered
Joined
·
6,139 Posts
i wouldn't swap unless i was re-tuning myself. but hey, that's just me though.
 
1 - 20 of 53 Posts
Top