To upper or lower pulley, that is the question.

[CobraSVT657]

Well I'm rounding up the last few parts for my Eaton swap and trying to decide on pulleys. I can either run a 2# lower with stock upper, or run a stock size lower and a 3.1? upper.. Just curious what combo's you Eaton guys are running and any benefits to either direction. BTW the Eaton going on mine is ported.

Thanks

[RacerX]

Keep the upper and run a larger lower. Less work involved and I believe less possible belt slip on the upper (more surface area).

http://www.mercurymarauder.net/gallery/data/579/EatonPulleyCombinationsUpdated 09-08.jpg

[ImpalaSlayer]

heres some number

my car
2lb lower 3.1 upper= 14lbs

Rex's car

2lb lower, stock upper = 11lbs


bigger the upper less belt slip you would have but i dont have any problems and neither does Rex.

[RacerX]

Stock upper and 4lb lower = 12 to 13psi ;)

[CobraSVT657]

Thanks for that chart... very good quick reference. Whats the avg. boost you Eaton guys are making with your pulley combos?

[ImpalaSlayer]

See my first post

[CobraSVT657]

heres some number

my car
2lb lower 3.1 upper= 14lbs

Rex's car

2lb lower, stock upper = 11lbs


bigger the upper less belt slip you would have but i dont have any problems and neither does Rex.

Would you say that 14# is the limit on a stock bottom? Or is that pushing it?

[SC Cheesehead]

Thanks for that chart... very good quick reference. Whats the avg. boost you Eaton guys are making with your pulley combos?

I put together a little spreadsheet with pulley combinations and boost for the guys that responded to thread I started a couple months ago;

Ave boost calculates to 11.5 lbs.

Ave. RWHP: 434 Ave. RWTQ: 430

[sailsmen]

Allways go bigger, less belt slip and spools quicker.

[DOOM]

DO BOTH!!!


MORE
POWER!!! :burn:

[CobraSVT657]

Just got off the phone with LFP... 2# lower getting shipped out today. :banana:

[RacerX]

BTW the Eaton going on mine is ported.
Just caught that! Posi or Steig? Mine is going to be ported also (Posi). That will lower your IAT temps, excellente!

[ImpalaSlayer]

DO BOTH!!!


MORE
POWER!!! :burn:

wrong, as sailsman and my self said, bigger pullys slip less. only reason i did a 3.1 is because there was a concern of hood clearance because the eaton sits farther forward then the trilogy. but its been proven since that there isnt an issue.

[ImpalaSlayer]

Would you say that 14# is the limit on a stock bottom? Or is that pushing it?
i wouldn't wana go any more, mines really dialed back though in the tune. i could make 470hp tomorrow if i really wanted to test my luck

[CobraSVT657]

i wouldn't wana go any more, mines really dialed back though in the tune. i could make 470hp tomorrow if i really wanted to test my luck

Having Doug at Billetflow as a longtime friend and Lidio tuning the car... and all the helpful direction from you guys.. I'm sure I'll be happy with the end result. :beer:

[CobraSVT657]

Just caught that! Posi or Steig? Mine is going to be ported also (Posi). That will lower your IAT temps, excellente!

Posi ported the one I have.. Friend had it done then before putting it back on decided to go turbo on his 03 cobra... needless to say I picked up alot of swap parts at the right time and price. :beatnik:

[ImpalaSlayer]

Having Doug at Billetflow as a longtime friend and Lidio tuning the car... and all the helpful direction from you guys.. I'm sure I'll be happy with the end result. :beer:
set it up like Rexs car then, that car was a blast to drive.

[CobraSVT657]

set it up like Rexs car then, that car was a blast to drive.

I have the 2# lower on the way.... so 3.4 or 3.1 upper or stock?

[SC Cheesehead]

I have the 2# lower on the way.... so 3.4 or 3.1 upper or stock?

A 2lb lower and stock upper will give you around 11 lbs boost.

With a conservative tune and stock exhaust, my car dynoed 423 rwhp and 411 rwtrq with that combo.

[RacerX]

Not to mention that your combo (stock upper, 2lb lower) is probably as much as you want to go with the stock motor and miles already on it. You're good.

[CobraSVT657]

Thanks... I think I'll stick with the 2# lower for now... I'll get a hold of Doug @ Billetflow for a stock size upper with hub. So I can change it once the built shortblock is done

[RacerX]

Nice! Should be able to get 15psi on the heaton with the porting and built block. Whipple time if you want more! :D

[Vortech347]

Good call. I'm having Posi port the one on our Cobra.

[CobraSVT657]

Nice! Should be able to get 15psi on the heaton with the porting and built block. Whipple time if you want more! :D

I might have a chance to get a 2.8H for a deal

[CobraSVT657]

Good call. I'm having Posi port the one on our Cobra.

He knows what he's doing

[RacerX]

I might have a chance to get a 2.8H for a deal
Sheesh, that would blow. :( Or suck depending on how you look at it! :D
Yeah, whipple down the line for me too. First, a bb stroker and a built trans/rear. Nothing worse than leaving parts at the track...

[DOOM]

Good call. I'm having Posi port the one on our Cobra.

Excellent choice! :beer: :banana2: