RR 2.65" upper puley w/ factory lower (w/ pics and dyno sheet)

[myslowstang]

When I was trying to figure out which pulley to go with it was hard for me to find info on using the 2.65" upper pulley. Many people told me not use the 2.65" because of belt slip but I've come to find out that the GT500 guys are using pulleys smaller then the 2.65" so I decided to give the 2.65" a try.

Here's what I found... I have very little, if any belt slip. I'm used a 100mm auxiliary idler, which you have to remove to put on/off the belt due to the high side wall of the RR 2.65" pulley. I used a Napa belt (part # 080740), I believe it's a 74 5/8”. The car made 14.41#s of boost. I have LT headers so I may have lost a little boost but I wouldn't think it'd be much. I'd guess that if I had the factory headers that I may have hit 15#s.

Here is a list of my mods so you guys know what I had and the results I got.

MODS
Posi Performance race port (on factory Eaton blower)
2.65" upper pulley (factory lower)
Accufab single blade throttle body and plenum
JLT 12" high boost cold air intake (new version)
SCT BA-3000 MAF with 105mm housing
60 LB injectors (from Sieman Deka)
BAP
MAC long tube headers
MAC off-road H-pipe
MAC 3" catback
ECG delete
BilletFlow 100mm idler pulley
Napa belt (part # 080740)


Cobra made
518rwhp
497rwtq
14#s of boost


Here are a few pics to show fitment

DYNO

Tuned by HBH

 

[96juicedGT]

Nice numbers!

 

[myslowstang]

Thanks! I just figured I'd put this out there for those guys that were like me trying to find more info on the 2.65" pulley.

 

[96juicedGT]

Posi port FTW!

 

[myslowstang]

Yeah he did a great job on the blower

 

[va boy]

Congrats, nice numbers, now you're a member of the 500 club.
I'll bet that thing screams, would love to hear it with that exhaust set up too.

 

[myslowstang]

I do love the way it sounds. I've only had the car back for the tuner for a few days. Videos to come, just give me some time.

 

[96juicedGT]

Yeah I would like to hear it also.

 

[myslowstang]

In order to get the 3" MAC catback to fit with the 2.5" system you have to cut off the 3" flange off the catback and weld on a 2.5" flange. It just so happens that a 2.5" pipe slides nicely right into the 3" pipe so it's an easy job.

I'll see what I can do about getting an exhaust video clip

 

[myslowstang]

Just a quick video of the car at WOT. Sorry about it being so jerky, I forgot to tie down the camera. I'll get some more videos later


500+ hp Cobra - YouTube

 

[myslowstang]

Just wanted to give you guys an update on things.
I've only been to the track a few times and so far my best run was a 11.6 @ 122mph
I only had a 1.8 60' so I still think there is room for improvement.
This was also on a narrow tire. M/T street radial 255/50/16 (26" tire).
I figure it's a low 11 car if I can get that 60' down a little bit.

 

[Lstruck03]

I ran the same pulley on a stage3 steggy port in the past, also with great results. I too noticed very little slippage. I eventually added a 4lb lower and a posi port with a dragon. Talk about tq!

 

[myslowstang]

I ran the same pulley on a stage3 steggy port in the past, also with great results. I too noticed very little slippage. I eventually added a 4lb lower and a posi port with a dragon. Talk about tq!

Now that I'm getting closer to 10's I'm thinking about adding a lower. How much boost did you make with the 4# lower?

 

[Lstruck03]

it would peak 18psi and hold ~16.5 .. stock engine with kooks lt's and no cats.

with higher compression, cams and big heads, it would peak and hold steady 15psi.

 

[myslowstang]

Yeah I'm not sure if I wanna spin the factory blower that fast. Maybe I'll get a 2# lower, 18# of boost seems like a lot on the factory blower.

 

[Lstruck03]

it ran like a champ. i had a afco h/e and a big i/c tank. never really had a problem with heat. I believe others have ran this pulley combo as well.

i ran a 2# lower at one point. coudnt really tell a difference with or without it. the 4lb made a big difference.

 

[chitowncobra]

Nice setup!:beer:

 

[myslowstang]

it ran like a champ. i had a afco h/e and a big i/c tank. never really had a problem with heat. I believe others have ran this pulley combo as well.

i ran a 2# lower at one point. coudnt really tell a difference with or without it. the 4lb made a big difference.

That's good to know

 

[snakerider]

Just wanted to give you guys an update on things.
I've only been to the track a few times and so far my best run was a 11.6 @ 122mph
I only had a 1.8 60' so I still think there is room for improvement.
This was also on a narrow tire. M/T street radial 255/50/16 (26" tire).
I figure it's a low 11 car if I can get that 60' down a little bit.

I ran the same tires as you my times are in my sig. The best 60ft I got with them was 1.7. But I have MM coilovers in front and rear with 575lb springs in the back and 375lbs springs in the front. Result of this suspension is zero weight transfer.
The car is actually setup for handling rather than 1/4 mile racing. But I'm happy with my times.