Pulley 101 .......info for dummies like me

[maxdmax]

Originally Posted by PQ

Mine was tuned with a 2.8 creating 8.5 -9 pound of boost and with a 3.2 creating 7.5 pounds. Vengeance told me that if I wanted to drive around with the 3.2 and put the 2.8 on for track days that the tune would adjust automatically.

Originally Posted by PQ

I'm running a 3.4 inch pulley now with JREs tensioner and making 7.5 pounds according to my OBD logger. BUT dropping to 48 pounds in fuel pressure. So Not sure what to think about that. Obviously I need a fuel pump upgrade.

Originally Posted by PQ

I don't have a clue why the low boost. Even with Janetty super tensioner it's only 7.5 with a 3.4 pulley. And it's as tight as it can be.

I went back and read the past few posts and just to clarify, did you pickup 2 PSI just adding the super tensioner? Did you change to a 3.4 at that time? I was thinking you were at 7.5 PSI on a 3.2. If you are in fact at 7.5 PSI on a 3.4 your car is exactly where mine was with the same setup. Are your RWHP numbers at 560 in your signature made at 7.5 PSI? If so you are right on what my car made factoring in the auto verses the manual. If that is the case from what my tuner says we have a setup that does not have as much restriction as some others, which is a good thing. He said for some reason some cars just do better with less boost than others. If that is the case then I think I can give you some good information on what will happen with the different pulleys front and back given our cars made almost exactly the same boost, crank HP on the same pulleys.

[lexlueger]

3.4 with OD rears@ 7.5 psi is low. As stated OD rears add about 3-4 psi. Boost numbers with the 3.4 W/O cam or LTH's is 10 psi. That's 13/14 + 1 for a C.A.I. Let's say it's 14 psi..... a 7 psi drop for a cam/LTH?

[PQ]

Originally Posted by maxdmax

I went back and read the past few posts and just to clarify, did you pickup 2 PSI just adding the super tensioner? Did you change to a 3.4 at that time? I was thinking you were at 7.5 PSI on a 3.2. If you are in fact at 7.5 PSI on a 3.4 your car is exactly where mine was with the same setup. Are your RWHP numbers at 560 in your signature made at 7.5 PSI? If so you are right on what my car made factoring in the auto verses the manual. If that is the case from what my tuner says we have a setup that does not have as much restriction as some others, which is a good thing. He said for some reason some cars just do better with less boost than others. If that is the case then I think I can give you some good information on what will happen with the different pulleys front and back given our cars made almost exactly the same boost, crank HP on the same pulleys.

No. My car only made 530 with the 3.2 at 7.5 pounds. With the 2.8 pulley at 8.5 to 9 pounds it made the 560. I figured I'd just keep both so I can be safe for my daily driving and put the smaller on when I want to. (only takes 5 minutes to swap them)

Later I realized that with a 2.8 pulley (with no slippage) it should be making WAY more than 8.5 pounds and I wanted to be sure I was getting what I should. If the belt slips all the time it will only get worse and I could be minus power and not even know it.

So I logged it with the 3.2 on it and got 7.4 pounds before I did the super tensioner and then afterward (after I installed the tensioner) I put the 3.4 pulley on it and got 7.5 pounds.

I want to log it again now with the 3.2 pulley to see what I get but I noticed my fuel pressure dropping to 48 pounds. I don't want to do any more boosting till I get a fuel pump. I only have the stock pump with a BAP. I"m not sure what the fuel pressure was when Vengeance did it but I don't think it's supposed to drop that low. And if I go to 8.5 it may drop lower???

But, anyway, mine is the auto and only made 530 with 7.5 pounds of boost. So I'm running my car daily at that power level till I get my fuel issue solved.

I don't like the 'Factory Freak' idea. I don't believe in it. Laws of Physics don't change from one place to another. Maybe a little, but not THAT much. In other words I don't know if I like the terms 'Some cars are different' ..... not when it's the same mods doing the same things.

[maxdmax]

Originally Posted by PQ

No. My car only made 530 with the 3.2 at 7.5 pounds. With the 2.8 pulley at 8.5 to 9 pounds it made the 560. I figured I'd just keep both so I can be safe for my daily driving and put the smaller on when I want to. (only takes 5 minutes to swap them)

Later I realized that with a 2.8 pulley (with no slippage) it should be making WAY more than 8.5 pounds and I wanted to be sure I was getting what I should. If the belt slips all the time it will only get worse and I could be minus power and not even know it.

So I logged it with the 3.2 on it and got 7.4 pounds before I did the super tensioner and then afterward (after I installed the tensioner) I put the 3.4 pulley on it and got 7.5 pounds.

I want to log it again now with the 3.2 pulley to see what I get but I noticed my fuel pressure dropping to 48 pounds. I don't want to do any more boosting till I get a fuel pump. I only have the stock pump with a BAP. I"m not sure what the fuel pressure was when Vengeance did it but I don't think it's supposed to drop that low. And if I go to 8.5 it may drop lower???

But, anyway, mine is the auto and only made 530 with 7.5 pounds of boost. So I'm running my car daily at that power level till I get my fuel issue solved.


I don't like the 'Factory Freak' idea. I don't believe in it. Laws of Physics don't change from one place to another. Maybe a little, but not THAT much. In other words I don't know if I like the terms 'Some cars are different' ..... not when it's the same mods doing the same things.

So the good thing we are on par with the pulley size at 3.4 and both were or are at 7.5 PSI. We upgraded my fuel pump and injectors when we went to 9.5 PSI. The difference in RWHP I would bet is that the tuner could not get the fuel to give you what my tuner was able to do with my car having a dual LPE fuel pump and bigger 65# injectors. My guess is you have your belt slip fixed and are running out on fuel and injectors. When you go with the OD back pulley I would either pulley up to a 3.8 and drive it or do a 3.6 and check the tune to be sure you do not max out your injectors or fuel. Then again you could just get a big fuel pump and 65# injectors and do the 3.4 with a tune and put down some big numbers LOL. Good luck!

OH on the factory freak thing, it is just that our cars make a couple of pounds less boot than most, this could be the cam, headers or a tune or a lot of other things not really a freak thing. Given my car is the same as yours does not make it a freak thing and I have seen a few others like this as well. I think most of them were RPO cars too, who knows maybe GM did a little something different on the first bunch of cars or something. Who knows, but to me it is a good thing.

[PQ]

Originally Posted by maxdmax

So the good thing we are on par with the pulley size at 3.4 and both were or are at 7.5 PSI. We upgraded my fuel pump and injectors when we went to 9.5 PSI. The difference in RWHP I would bet is that the tuner could not get the fuel to give you what my tuner was able to do with my car having a dual LPE fuel pump and bigger 65# injectors. My guess is you have your belt slip fixed and are running out on fuel and injectors. When you go with the OD back pulley I would either pulley up to a 3.8 and drive it or do a 3.6 and check the tune to be sure you do not max out your injectors or fuel. Then again you could just get a big fuel pump and 65# injectors and do the 3.4 with a tune and put down some big numbers LOL. Good luck!

OH on the factory freak thing, it is just that our cars make a couple of pounds less boot than most, this could be the cam, headers or a tune or a lot of other things not really a freak thing. Given my car is the same as yours does not make it a freak thing and I have seen a few others like this as well. I think most of them were RPO cars too, who knows maybe GM did a little something different on the first bunch of cars or something. Who knows, but to me it is a good thing.

Got it.

I wonder if a bigger pump and injectors would actually make me more power? The car would have to be automatically nannying the tune because of running out of fuel which would NOT be a good thing.

I've got a good set of XA coilovers that I am going to sell to help pay for a pump and maybe injectors. But that's my next move. Gotta get my fuel right.

[maxdmax]

Originally Posted by PQ

Got it.

I wonder if a bigger pump and injectors would actually make me more power? The car would have to be automatically nannying the tune because of running out of fuel which would NOT be a good thing.

I've got a good set of XA coilovers that I am going to sell to help pay for a pump and maybe injectors. But that's my next move. Gotta get my fuel right.

The pump and injectors won't make more power but they will let everything else work and the tuner tune the car for more power. If you want to move up any more than the 9.5 psi you should do the pump, injectors and meth as well. Then you can make some power I am making 678 RWHP and 671 TQ on a maggie with an OD cog drive and 3.4" pulley at 12 PSI. You should be able to get within 5% of that with an auto. So you could see 640 or better RWHP at 12 psi. LOL

[PQ]

Originally Posted by maxdmax

The pump and injectors won't make more power but they will let everything else work and the tuner tune the car for more power. If you want to move up any more than the 9.5 psi you should do the pump, injectors and meth as well. Then you can make some power I am making 678 RWHP and 671 TQ on a maggie with an OD cog drive and 3.4" pulley at 12 PSI. You should be able to get within 5% of that with an auto. So you could see 640 or better RWHP at 12 psi. LOL

Even safely I'd be scared to go over 9psi. Isn't that too much on a stock RA?

[maxdmax]

Originally Posted by PQ

Even safely I'd be scared to go over 9psi. Isn't that too much on a stock RA?

My tuner is running stock internals ls3s as far 16 PSI but only under some strict setups. He has gen5s camaros with prochargers and stock bottom ends at 14 PSI. He stopped at 12 PSI on mine due to the high torque a maggie makes. You can do it and as long as it is tuned right and the meth keeps working you are reasonably safe. You just have to be hooked on the meth, that is where you are taking 95% of the risk. Some say a big risk some not so big, I just watch that little light on my dash a lot and have a 4 gallon meth tank LOL

[2010SSRSM6]

Originally Posted by PQ

Even safely I'd be scared to go over 9psi. Isn't that too much on a stock RA?

I'm at 9.5 #'s of boost and running on 91 octane gas. If you have 93 available, you should be safe up to 12 pounds with the correct tune.

There have been several people on here running 12 pounds for a while, but that is WAY to much for me to feel safe. I honestly wouldn't want more than 10 pounds of boost on a stock RA. The only way I would do that in an auto is with the LS3 conversion, which you already have, so I would think you would be fine up to 10 pounds of boost.

It isn't like you will will always be running around on max boost.

[PQ]

Originally Posted by 2010SSRSM6

I'm at 9.5 #'s of boost and running on 91 octane gas. If you have 93 available, you should be safe up to 12 pounds with the correct tune.

There have been several people on here running 12 pounds for a while, but that is WAY to much for me to feel safe. I honestly wouldn't want more than 10 pounds of boost on a stock RA. The only way I would do that in an auto is with the LS3 conversion, which you already have, so I would think you would be fine up to 10 pounds of boost.

It isn't like you will will always be running around on max boost.

True. And I have 93 available all day long here.

Once I get my fuel done I may get it dyno-tuned again.

[zebra]

you get this junk worked out before the engine quit?

[PQ]

Originally Posted by zebra

you get this junk worked out before the engine quit?

I never got it to a dyno. I bought the JRE supertensioner but I suspect it still was slipping.

I have no way to know until I get the new engine dropped in over the next few weeks.

[zebra]

well what about now?

[PQ]

Originally Posted by zebra

well what about now?

Waiting for my cog pulleys and belt and fuel rail to come in.