Just installed the aam plenum and i love it. But it feel like i lost some low end torque. Just doesn't feel as fast off the get go but man does it fly up top. I am just wondering if i get the crank pulley will that bring back the low end power that i think i am missing.

Any thoughts and what type of pulley should i get. I don't want to mess with the accessory pullies. Whats a good one.

 

The easiest thing to get is the KJR Lightweight pulley. Same diameter as stock but like 6lbs lighter. You get to keep your stock belts - couldn't be easier. Looks good too!

 

I agree the KJR pulley works great for me. I didn't want to underdrive any thing.

If you have an automatic PM me and I give you some hints on who to get the stock one off. Manuals are easier becaue the damn engine wount keep turning.

 

so this is different than say the UR pulley....this retains the harmonic balancer and is just a lighter pulley....correct? tx

 

the KJR pulley retains stock diamater but is made out of a solid piece of aluminum
through testing we learned that the pulley does not need to be 2-piece.
roughly 4.2 pounds less in weight
stock 6.4
KJR 2.2

Jon-KJR Staff

 

I installed the UR pulley and gained 6hp in before/after dyno tests. I have had no issues with voltage, A/C or anything. I did have it installed at a mechanic's shop though, didnt want to mess with that.

 

Can you tell a difference off the line?

I am kinda ignorant to mechanical shiat...why is underdrive worse off than the KJR pulley.

I heard that the underdrive pully can net 8-12 rwhp.

I just want to make the car quicker....cheap.

 

Well, to be honest, I didnt notice squat. I only know I gained 6hp because I saw the dynos before and after. There are all sorts of posts saying how terrible a smaller underdrive pulley is and how its going to blow up your engine. There are as many posts saying its the latest thing since sliced bread and it wont do anything. The more common concerns I saw were lower voltage and the A/C not cooling as much. Being from Florida, I can tell you my AC is just fine. I notice at idle that voltage drops to 12.5 or 13v once in a while, but so far I haven't had any issues. Then again I dont play XBox on my Z, so ....

 

My engine definitly revs quicker. My son in the passenger seat noticed a difference. Also, I noticed that it seems to run up higher when starting too.

 

The UR Crank pulley would be the way to go IMHO...

Especially if you are going ot do a reflash down the road with a Higher RPM...

An Underdrive Pulley and High RPM's will cause your accessories to NOT be OVERDRIVEN... if you are in the high RPM's all the time an Underdrive pully will actually better for not over working your power steering pump / water pump / etc...

 

Okay....so it revs quicker...does that equate to faster acceleration.
I just feels like the car is slow off the get go.

 

The thing I tell my customers is to sit in the car and try to remember what the car feels like prior to the install. Count in your head how long it takes to get to redline from a 30mph roll and so on. or count how long it takes for the rpms to fly up and drop when you are in neutral. Then after do the same. A good analogy is a runner with weights on his leg. He uses the same energy when running both ways but without weights he can lift his leg faster for his next stride.

 

I like that analogy. Thanks

 

The UR Crank Pulley added 8 RWHP across the full RPM range on Jeff's modded Z...

On a turbo car it would be more...

 

Why would it be more when using a turbo?

 

Turbo works off exhaust gas blowing by to spin the turbine. If the car can rev quicker that means faster exhaust gas blowing by helping the turbine spool up faster. Or someting like that.

 

most every modification you do that iincreases NA horse power will increase turbo horse power...

A free flowing exhaust will improve your NA horse power but, with a turbo car it will increase it some times 2 - 3 times as much...

high flow cats will increase 8-12 RWHP on an NA car... on supercharged cars it will do up to 40RWHP... same with turbos...

etc...

 

so i still dont get why people say an underdive pulley is bad for your car. Although i must say 12-13v is bad for your alternator. My understanding is you need 14v, otherwise you risk damaging your alt.

 

So.....you can feel the difference and should increase your off the line, low end torque?

 

here is a dyno of just the UR Crank Pulley added... Air Fuel got messed up because the re-flash got screwie... when it was reflashed properly the air fuel was better...



as you can see... it added HP and TQ across the full RPM range...