pulley change

I am trying to decide if I want to change the pulley on my 04 cobra. I need to know if it's worth it: is there going to be belt slippage, how long can I expect the charger to last due to increased demand on the bearings due to the increased heat.

If it is done, will there be any other mods that needs to be done.

Reply to
qk_slow_qk69
Loading thread data ...

have you done any mods to it yet? i am in the same boat as you trying to decide whether to do the pulley/tune. its my daily driver so i am kinda leary about it, but i'm sure that it would be wild, man.

if i do do it, it will be with the 4-piece idler setup from billetflow. from what i read, you should definetly do at least one idler to minimize belt slip.

i have already done an intake and exhaust on my car. i would recommend at least those mods before or with the pulley swap so that it can breathe. (and of course also the dyno tune)

good luck with your choice. also keep in mind, the more power you make, the more likely to break other drivetrain pieces.

chris

04 comp orange cobra vert

Reply to
Chris Shea

Here we go again... Underdrive pulleys free up a very small amount of power... where they shine is in cars that are subject to continuous high rpm operation. They can reduce the chance of winding separation in the altermator as well as reducing cavitation in the waterpump. For a daily driver subject to leng periods of normal to low rpm operation, you can expect poor charging system operation, possible overheating and even reduced power steering assist at low speeds. Any serious horsepower gains will be more placebo effect than actual........ please don't trot out the dyno tests that show a whopping 2 horsepower gain. In a street car this is pretty much negligable, especially in light of the downsides.

Ahhh, I can get a bigger alternator that will offset the reduced rpm..... and the bigger alternator will chew up the appropriate amount of horsepower to maintain charging system efficiency..... can you say "Back to square one??"

It's not difficult to apply logic to the "don't buy" side of the equation..... with you young'uns, the glitter of billet aluminum far outweighs any sensible decisions.

Reply to
Jim Warman

Akshully Jim, I'm pretty sure he meant the upper blower pulley on the S/C. Which by itself has added gobs of power.

Reply to
Jafo

Adding my $0.02

Get an aftermarket chip or one of the reflashed programs like Steeda's. More boost (depending on how small a pulley) at the least would more than likely warrant changes to the timing. Not sure whether you'd need bigger injectors. As far as life of the S/C, I don't think thats a problem..although theres not a lot of info on that, seein' as the blower has only been on the Cobras since '03. Like any performance upgrade, it kinda depends on how much you use the LOUD pedal.

Reply to
Jafo

Yea Jim. Can't you read? :)

Reply to
Mark C.

No, we're not :-) You are right BUT he is talking abotu the pulley's on the supercharger on his Cobra. You can get HUGE increases by changing them. Best bang for the buck ever. One thing though; Make sure the AF ratios are adjusted as well. He needs a predator that's programmed to use the extra boost.

Remove NO-SPAM from email address when replying

Reply to
Rein

Probably guilty as "charged"..... I'm not used to calling assemblies in this kind of short form and took "charger" as someone forgetting what an alternator is rather than supercharger ( a term more easily understood).

What's in a name??? Who knows what a gudgeon pin is... or a front wing.... or a demister...

You guys are just like everyone at work.... "let's pick on the old fart".... (just kidding 8^)

As I recall, the supercharger (yes, supercharger) is underdriven to start with. Think of it this way... A normally aspirated motor of (just for argument) 300 cubic inches, thinks it's a 300 cubic inch motor.... at 7 pounds of boost, it thinks it's a 450 cubic inch motor and at 14.7 pounds of boost it thinks it's a 600 cubic inch motor. Of course this doesn't take into account atmospheric pressure variations, intake air temp or pumping losses...

Reply to
Jim Warman

as far as breakage, the good thing is the lightning guys have been overspinning this eaton m-112 unit for a few years and supposedly durability problems are rare.

here's what is making me hesitate on my decision though: eaton's website shows that the max rpm for the m-112 unit is 14,000. on a stock cobra, the blower spins to approx 13,580 at redline. (3.65 upper, 7.625 crank). but at redline with an aftermarket 2.80 pulley and stock lower, the blower spins to a whopping 17,700!

does it survive because the wot runs are usually brief? that the time spinning over 14K is so little? these are the things i am trying to learn more about. of course i guess i could just rob a bank and go twin-screw... =)

chris

04 comp orange cobra vert
Reply to
Chris Shea

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.