03 Cobra Pulley / Tune Questions...Help!

1wildGT

Founding Member
Jun 4, 2001
1,026
6
38
Abilene TX
Ok, I'm ready to get a smaller pulley / tune for my 03 Cobra. Is the Diablo Predator and 2.81 pulley a good combo. I also want an additional idler pulley to wrap the belt around the smaller blower pulley. Which 2.81 pulley and idler pulley is best and how do I know what length of belt to get once I get a good idler pulley. Is there a place for one stop shopping for this stuff online?

I don't want belt slip and want a safe tune.

Thanks for any help guys. :)
 
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Where to start. Ok, there are many different pulley sizes you can go with. Really depends on how much you want to spin the Eaton up.( or over spin it :( )You have sizes anywhere from a touch smaller than stock all the way down to a 2.76. Some like to do an upper and lower combo.(Ex: 2.93 w/ 4# lower. Got tourque :banana: ) Either way you will need a good tune. The Diablo Sport Predator is a good tuner and I recommend a nice dyno tune to go with the handheld tuner. Find a tuner in your area and use whatever he uses.( Predator, SCT, etc.) As far as which pulley and idlers to go with the 2 most popular seem to be Billetflow and Reichard Racing. Can't go wrong with either. I know you can buy the upper and all idlers and snub bracket directly from Billetflow, not sure about RR. As far as which belt to use, Billetflow has a chart on their website telling you which size you will need. Good luck. :nice:
 
Now I need to decide how many idlers. 4 would be nice they look awesome, but it's an extra $125 and seems like a cosmetic upgrade. My nearest tuner is 200+ miles away so I need a "safe" tune that I can install that will provide the best gains. Are there any other recommened other than Diablo Predator? Anyone else running Diablo Predator with 2.93? What gains can I expect?
 
I just bought a Redfire Billet Flow 3.1 (whimpy but price is right) and a Billet Flow 100mm aux....I will be putting a 6lb lower crank on soon from Billet flow as well. serious HP dude...period. 50 maybe 60 with a tune
 
1wildGT said:
Now I need to decide how many idlers. 4 would be nice they look awesome, but it's an extra $125 and seems like a cosmetic upgrade. My nearest tuner is 200+ miles away so I need a "safe" tune that I can install that will provide the best gains. Are there any other recommened other than Diablo Predator? Anyone else running Diablo Predator with 2.93? What gains can I expect?
Some just opt for the main idler, but I recommend to do all 4. The stock one's are crap and have been known to break under heavy load. The Diablo Predator has canned tunes loaded in to it so you can go with a 2.93 and load the performance tune for that pulley into your car. Just remember that these tunes are crap and you will be leaving some power on the table with it. Dyno tune is highly recommended. Another handheld you can go with is the Superchips SCT. It would be worth it to you to travel the 200 miles and have everything installed at once and get the tune done at the same time. :nice:
 
Just so it's clear... you only need the one upper idler pulley to ensure good belt wrap around your 2.93. The other idlers are better than the stock pieces, and they do look very nice, but bottom line is they are cosmetic and are not required.

The pre-programmed pulley tunes should only be used to get your butt to a dyno and have the car tuned properly. 99 times out of 100 those tunes are safe, but it's the one time where your car just happens to be a little leaner than the rest....
Give yourself some peace of mind and use that canned pulley tune to get you to a dyno and nothing more.

U.M.
 
I just bought the Billetflow upper idler...(Thanks U.M)

I have the 2.8 and I also just bought the Gates 74" Belt. In case you haven't researched it, the 2.93 requires the same as the 2.76/2.8 pullies.
 
Uncle Meat said:
Just so it's clear... you only need the one upper idler pulley to ensure good belt wrap around your 2.93. The other idlers are better than the stock pieces, and they do look very nice, but bottom line is they are cosmetic and are not required.

The pre-programmed pulley tunes should only be used to get your butt to a dyno and have the car tuned properly. 99 times out of 100 those tunes are safe, but it's the one time where your car just happens to be a little leaner than the rest....
Give yourself some peace of mind and use that canned pulley tune to get you to a dyno and nothing more.

U.M.
:D They do look trick, now don't they. Cosmetic only. :rolleyes: I do agree 100% with Meat about the canned tunes. Only to get to your dyno tune. :nice: Be safe.
 
Think my mind is set on 2.93 billetflow with 4 idler set-up and custom SCT tune by Dallas Mustangs. I'm told I don't need to really worry about the stock MAF pegging with these mods.

Now, do I need to be conerned about the stock plugs/stock gap with the increase boost? Will they blowout at high RPM?

Anyone running 2.93 on stock plugs??? :shrug:
 
The stock Motorcraft plugs (AGSF22FM1) are a fine wire platinum plug and are surprisingly good. Even though I'm still on the stock pulley I run the AGSF12FM1's myself which is what came on the 1st run Cobra's from the factory.

I had run the NGK TR-6's and after only 3K they looked really bad and my idle was never smooth so I went back to the stock Motorcrafts and have never looked back. If I were you I'd try re-gapping the stock plugs to .035 and running them first. It won't cost you anything but a little time.

Oh, and yes there are guys running the 2.93 on the stock plugs.

U.M.
 
I have got a 2.9 pulley, no idlers, 74" gatorback belt, SCT hand held tuner,
C&L C.A.I. 95mm mass air meter, and a 3"
mac cat back exhaust on my cobra. It made 437hp and448tq. The car would have made more but my clutch was slipping around 3500 rpm. They also told me that for a hand held programmer with fixed tunes it that I would need to go to a 2.8pulley because my a/f was geting as low as 11.5. The 2.8 pulley is suppose to keep me around 12-13.
 
my roush said:
I have got a 2.9 pulley, no idlers, 74" gatorback belt, SCT hand held tuner,
C&L C.A.I. 95mm mass air meter, and a 3"
mac cat back exhaust on my cobra. It made 437hp and448tq. The car would have made more but my clutch was slipping around 3500 rpm. They also told me that for a hand held programmer with fixed tunes it that I would need to go to a 2.8pulley because my a/f was geting as low as 11.5. The 2.8 pulley is suppose to keep me around 12-13.
No, what you need is a custom tune! That 95MM MAF needs to be accounted for in your tune! Adding an aftermarket MAF WITHOUT tuning specifically for it on these 03/04's is just asking for trouble. The stock MAF is good for 500 RWHP so why you thought you needed a bigger one is beyond me. :shrug:

Your car should be closer to 460 with those mods. Get to a respectable tuner ASAP and have him hook you up!

U.M.
 
1wildGT said:
Think my mind is set on 2.93 billetflow with 4 idler set-up and custom SCT tune by Dallas Mustangs. I'm told I don't need to really worry about the stock MAF pegging with these mods.

Now, do I need to be conerned about the stock plugs/stock gap with the increase boost? Will they blowout at high RPM?

Anyone running 2.93 on stock plugs??? :shrug:

Yeah, I am. I'm putting down 459hp and 458 tq.....no problem. If you can't get to a dyno....get a Custom Tune from James @RWTD.