Hopefully this is an easy one. Ive got a long road trip coming up and was wondering what needs to be done when swapping out pulleys. I bought mine earlier this month with a 2.8 pulley already on it, no stock pulley came with it. Im thinking about putting on a huge pulley for the 15 hours on the highway when I wont need any boost or supercharger drag. What must be done? (And I can only assume the last guy got a tune for it, it doesnt throw a CEL and I THINK the injectors have been upgraded)

Thanks for the help

 

I'm not a rocket scientist here, so run this by me real quick....wouldn't a bigger pulley cause more drag? Srs question.

 

A bigger pulley gives the drive belt more leverage on the supercharger. Same principle behind underdrive kits.

 

This dosent sound right at all. Do you have larger fuel injectors on it? Cause if you swap pulleys, youd have to retune. Simple logic. And you'd have to put the stock injectors back on. Please explain more with what you have.

 

Id love to be able to tell for sure if the injectors arent stock. What should I be looking for?

 

pull the injectors and see what color the o rings are

 

If you have stock injectors, and a 2.8 pulley....rip that bitch out and put a stock one on.

 

I would leave it as is. Ur on the highway no boost anyway. Its not throwing any codes should be alright. And there's no ecotech kick to worry bout.

 

Are you people serious...

A 2.8" is not crazy by any means, it's rather sedate actually.

If your not on the throttle the boost is bypassed so you won't lower your MPG's. Your IAT2's should be really low too as your not 'making' any boost.

You can run larger injectors with a larger pulley, think about E85 where this is necessary.

Now it's a different story if you have an improper setup and you have stock injectors and a 2.8" pulley.

You need a retune for a larger pulley as well as a smaller one, unless you're going up one step and the tune is good. Less/more air coming in = your engine not knowing WTF is going on. The tune PCM can adjust a bit, but not indefinitely.

In a nutshell so long as you have the injectors and a tune, you'll be fine...

 

this. don't start swapping pulley's if you don't know what you have in the first place. if you're that paranoid about the drive, do the smart thing, find a good shop that will dyno tune to check the tune for you. if everything checks out fine, a 15 hour drive is no big deal, even with some minor work done. and a 2.8 pulley is pretty standard around here. you're definatly not doing anything to the supercharger, or causing bad drag on the engine.

 

Stock LSJ injectors have lime green tops and are otherwise silver/aluminum in color.

(found these on a quick google search)


If you don't retune for the larger pulley you will cause more damage than good than keeping the smaller pulley (unless the car isn't tuned for the smaller pulley). If the car is tuned for the pulley you have on it, it will be fine. Now unless you wanna go back to stock in general than go for it, but everytime you change the pulley or injectors you NEED a re-tune.

 

Well of course I was just mainly hoping for the mpg to bump up a bit. Would this be the case if I were to jump from the 2.8 to say a 3.3? With a proper tune of course

 

As long as the tune's are equivelent and one isn't running richer than the other... as far as the pulley itself making an effect. It will make no difference on the highway or normal driving conditions.. now if you start getting on the throttle, the smaller pulley will suck up more gas because it's forcing more air in the engine thus requiring more fuel to keep the correct AFR mixture. It all depends on how you drive it though..

 

This.

I went from a 2.9 to a 2.7 and my gas mileage didn't change at all.

 

i went from stock to a 2.8 and my mileage got better surprisingly. its about the same in town but a few mpg better on the highway. i average about 35mpg if i set the cruise at 60. dont know how common that is tho...

 

If your car has a 2.8 pulley and upgraded injectors then don't touch anything because you have a long drive.. Changing pulleys isn't going to get you better gas mileage. The supercharger has a bypass that opens when your cruising. No boost either way. Doesn't matter what size pulley you have..

 

Yeah I get that it has the bypass I wanted to know if the bigger pulley would result in less supercharger drag but based on what Im seeing here Im not gonna bother with it. I already get 30 hwy easy. A little off topic but how the mileage with the TVS?

 

It takes less than 1hp to spin the blower when the bypass is open. Changing the pulley is a waste of time.

 

I swapped my 2.8 to 3.06 for my highway trips so I could run regular and save some wear and tear on the blower. I just kept the boost below 5psi. It only takes 5 mins except when I lost a screw and I only had 3 to start with so I had to swing by the hardware store to get more.

I am cheap like that. I see it as allowing me the race for "free" cause i saved money that one time.

 

As someone who's actually done it would you say its worth it?

 

People who have no idea how a ecu works need not reply to this thread.

Going to a larger pulley from a smaller one does not NEED a retune. It would perform better with a retune because with less boost the timing could be advanced. The car will not start to knock from less boost lol.

If you downsize pulleys that is when you go from a tune being highly recommended, to actually needed.

 

That helps. With the larger injectors hopefully fuel delivery wouldnt be a problem when going to a bigger pulley, my big was with other aspects like the timing A/R and the potential to use a lower octane fuel

 

I'm assuming you meant A/F? If so the ecu uses the maf to measure incoming air to calculate the amount of fuel to add. If you change the pulley, it wont make the maf incorrect, and fueling will still be fine. the ecu also uses ve tables, which use pressure, but the concept is still the same.

as I said before, your timing wont be what it could be due to the fact that it was retarded to allow for more boost with the smaller pulley. so you wont have as much performance as you could on the larger pulley.


Due to you most likely having less timing than stock most likely, I would say you would be fine to use regular if you also use a stock sized pulley(3.3")

 

timing advance/retard

 

Lol, I thought there was a comma inbetween timing and A/R. Its way to late. bed time lol