Overspinning Eaton or What?

[getstung]

Had the 3.1 in pulley for the first upgrade and went straight to the steeda 2.8 took the car to the dyno this week and got less horsepower than the 3.1. but I made 37 more on the torque end. Watching the boost gauge it peaked out at 15 psi then started dropping off when we hit 4000 RPM and went down to around 12 psi. Dont really know what to do about it. i hear people talking about the 2.76 and a different lower pulley setup . just wondering on what some of your thoughts are and if i should switch out the lower with the setup i have now thanks


Mods: Steeda 2.8 in pulley, 100 mm idler pully, Diablo Flash Tuner, UPR o\r X, Flowmaster catback, M/T ET Street Radials--NOS wet kit not installed yet
3.1 made 447RWHP/427RWTQ
2.8 made 434RWHP/465RWTQ

 

[04cobracop]

2.93/4#lower and have some fun. You really need to get that blower ported!!!!

 

[04SLOBRA1]

belt slip or clutch slip. same dyno?

 

[Titter]

That's kinda weird..more that likely belt slip. I have the same set up as you do and I hit 468RWHP and 503RWTQ. Steeda did my tuning with the SCT XCAL2 and there software.

 

[93 347 Cobra]

belt slip or clutch slip. same dyno?

+1

 

[getstung]

All done on the same dyno. I just got back from dinner and i ran the car hard on the way home playing with a firebird. I dont think that its the clutch because it would slip when i stand in it in all the gears right. Anyways the guy with the same setup as me, those are the numbers I thought i would have too. With the 100mm tensioner i shouldnt have the belt slip right. I guess im gonna have to get me a lower and see what happens next.

 

[93 347 Cobra]

You might not be able to tell if the clutch is only slipping a little bit. The snub idler should prevent any belt slippage.

 

[Titter]

Well I have the 100mm idler with the snub but i do lose boost and HP at the high RPM range. Just after 5700 RPM my boost drops off to about 10PSI. I think im going to get the idlers to help with the belt slip. Not sure why your HP is that low. Who does your tuning for you? You should get steeda.ca to give you a mail order tune as i was really impressed with the numbers that i recieved

 

[Blown04GT]

Can you post a pic of the graph? Most of the time you can see the belt slip in it. I currently run the 2.8 and snub idler and don't have any issues. According to the chart on Cobrabob's site, just a 2.8 is not overspinning the Eaton.

 

[Yellow2003]

belt slip or clutch slip. same dyno?

+1 (Leaning toward belt)

 

[Titter]

Ok guys heres the graph to show you the boost drop off. The red line is the boost and the blue line is the A/F ratio.

http://www.facebook.com/photo.php?pid=58413&id=513375817
http://www.facebook.com/photo.php?pid=58414&id=513375817

My set-up is a 2.8 Upper with a 100mm idler with snub, HE, cat-back, TR6 plugs, and a K@N. With a SCT tune from Steeda.ca. Not to bad for that kind of set-up pushing 468rwhp and 503rwtq. I recommend Steeda to everyone.

 

[iBiTe03]

i notched my tensioner and run no idler pulley and mine pulls a constant 15psi through all rpms...