Has anyone changed pulleys yet? I've heard the theories on why not to change them. Some of the Performance shops around me say they have put changed several of them, And they say that it helps, But there very broad about the won't rave about them or talk down about them. I haven't run into anyone who has done it yet, just people who say there buddy has got one? Whats the deal from people who HAVE CHANGED YOUR?

 

If you like over-reving your supercharger and straining it for a possible grenade under the hood its a great Idea.If you want power maybe you should Stick to a chip/filter combo.

 

From what I’ve gathered from this forum, this is the deal.

There’s a Jag out there that uses the same Eaton blower as our L, but it’s spinning a little bit higher than us 14,000 rpm. So some people use a smaller pulley to bump up the L Eaton blower to 14,000 rpm.

This could be O.K. on its own, but the problem arises when you try to use the pulley and an after market chip. Most of the chips over rev the L Engine a little, plus most chips make more HP and fix a few things than the pulley alone. A dangerous combo.

Before you try this get a hold of Sals PSP web page, it explains this better than I can.

 

Has anyone tried putting a bigger blower on their L yet? And if so how much additional poer did you get?

 

I am running the smaller pulley, love it, it gets me up to 12.5 psi on the boost, using a Matco Boost gauge. I have also set my shifts points lower than most and am not having any trouble with the pulley at all. It has helped lower the max HP down into the power curve, now 405 at 4740 RPM. Its worth the effort but you must lower shifting points to build in any safety on the SC.

 

im running the smaller pully ,trans shifts at 5600 ,or i can put the other chip in and lower the shifts to 5200.the pully seems to make the best differance down low by getting the boost up quicker.by shifting at 5600 its hard to see any real improvement over the 5200 shift.so i would say put it on but keep the 5200 shift points and put in a transgo shift kit.

 

But the last two posts only prove that their SC are turning 14,000 again, am I missing something here? No improvement!

 

14k rpms is not the blowers rpm limit, it is just where the blower is at peak efficiency without a intercooler. The intercooler makes the whole system more efficienet. There know reason you shouldn't be able to over drive the blower. there is no way that ford would put a product that is that close to the edge on a vehicle, if 14k was the rpm limit of the supercharger.
For you guys that think that you should just put PSP filter kit instead of a pulley, because the boost increase is the same. What do you think would happen if you put the pulley on too! Your boost gauge was at 12, now it's at 14. boost equals HP. Anything you can do to help the supercharger breath better will make more horsepower. The pulley will also build the boost faster! There are some trade-offs with runing a smaller blower pulley. it will gennerate more heat. Is the aftercooler that ford put on our trucks efficient enough to compansate? maybe we'll need to run ice water through the aftercooler instead of the luke warm coolant that runs through there now.

As far as the pulley and the shift points of the chip. The engine is only going to be running from 5200 to 5600 for a split second. Thus the supercharger is only going to "over spinning" for a split second. maybe the answer is the set the chips shift point somewhere in the middle? 5400? This is all realted the just how unefficient the supercharger becomes beyond 14k rpms. ANY EATON SUPERCHARGER DIVISION ENGINEERS OUT THERE?

I was hoping some one out there had dyno tuned there truck with a pulley. And had some results one way or the other. That is the only thing that will tell us where the supercharger makes the most horsepower. So the arguement about shift points and "over spinning" can be put to rest.

 

If I can remember correctly 1BADTK got 10 hp from the pulley on the dyno. Correct me if I am wrong Andre.

 

10 would be fudging, it was more like 9 HP, it was also the last thing I did for improvements. Nothing left to do but N20, and I am not convienced thats the answer either. There is room for more by spinning the SC at a higher RPM but again I like the idea of a little safety. My main goal was to reach max HP earlier in the curve. The boost increase was just a gift .

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4rts2nv,

I have some questions for you:
Are you a Design Engineer for either Ford or Eaton Corporation?
Do you even understand the concept of torsional vibration or the concept of a natural frequency of a mechanical object?
Have you obtained Eaton manufaturer specs on the blower, ie. where did obtain obtain information that 14,000 is not the max rpm of the blower and that the peak efficiency only occurs there?
How can you say there is no reason that you cannot overdrive the blower? Have you been speaking w/the Design/Test/Failure Analysis Engineers at Eaton Corp?

Everything that is designed into this vehicle (and every vehicle on the road), has been engineered and designed to operate within certain parameters. When you start operating them outside of those parameters, you have no idea what can possibly happen.

I'll give you an example. I have been riding Polaris snowmobiles for about 20 years now. I have a 1987 Indy 600 (triple cylinder, 600cc liquid cooled). It was designed to operate at 8,000 rpm at WOT. I put a set of pipes on it years ago. I kept breaking crankshafts, yes completely snapped many cranks in the motor. Well, with the pipes, the motor operated at a peak rpm of 9,000 rpm. The problem was this: The natural frequency of the motor was 8,300 rpm, a mere 300 rpm above where it was intended to operate. Well, anytime I hit 8,300 rpm (and this was only for maybe a split second) as the engine would rev through this rpm quickly and operate at 9,000 rpm, I was literally destroying the crank. I went through about three cranks within SEVERAL HUNDRED MILES till I discovered the problem, and then immediately brought my motor to run at a peak of 8,000 rpm. Since that time, I have not broken a crank.

So, when you make statements like you have made, you better have some statistical data to back up what you are saying. And if you are wondering, yes, I am qualified to make the statements that I am making as I am a degree'd Engineer.

 

Well Peter B,

No, I don't woork for Ford or the Eaton corporation.

I am however A Design Engineer for General Motors. How did ya guess? And yes I understand torsional vibration, and ferquency.

You a absoultly right. I was wrong to say that 14000 rpm is the point of max efficiency. I don't know where that point actually is. But that is what I would like to find out.

Your snowmobile theory as applied to our situation would suggest that people shouldn't even put a chip in there trucks, because moving the shift point from 5000 to 5500 will make the supercharger spin form stock 12700 all the way up to 13900.
Do you think chips are ok?

lets come down to reality. Do you really think a company like Ford would put a product out the door that is that close to a catastrophic failure. I know for a fact that GM won't. (These are things you learn working for the big three. As little risk as possible)

I haven't talked to anyone from Eaton YET! I have talked to a test engineer from Ford who did some work on the lightning engine. I know this is hearsay put, he said they played with smaller pulleys, and didn't have a problem with the supercharger. I don't know at what rpm they where running the motor @. One other interesting thing he said was that the stock short block won't make much more then 500 Horsepower before blows up.

All of this is why I still haven't put the pulley on that I've had for 8 months.
Truth and facts about changing the supercharger pulley is what I'm after!

Just doing what it takes to stir the pot!

 

Can anyone say....AAAhhhhh! THis is not the first time the 500HP issue has come up nor will it be the last. Don't forget the crank either, not well made, just OK. Motors need a serious balance job. I have seen one cratered with a 250 shot of N2O, blowed the bottom out of it. One Big Mess........

 

4rts2nv,

Well, I'm glad I washed my feet yesterday (open mouth, insert foot). Design Engineer for GM, oops, I guess you do know about these type of topics that I questioned.

Very interesting points that you are making. Yes, I know what you are saying that you don't believe that Ford would build something so close to catastrophic failure. But, raising the shift point approximately 400 rpm with the chip is not alot, but as you are aware, there is roughly a 3 to 1 ratio between engine speed and blower speed. Therefore, raising blower speed from 12,700 to 13,900 rpm is approximately a 9% increase in speed. Now, I don't know what the max rpm rating of the blower is, so I can't make any claim as to whether it will fail when you increase the blower speed beyond, say, 14,000 rpm.

If indead the max rpm of the blower is 14,000 rpm, then putting on a chip and a pulley would truly exceed the limitations of the blower. Will putting a chip only on result in catastrophic failure-I don't believe so, if again, the actual max blower rpm is 14,000, as the shift point, although increased from stock, will still keep the blower below max rpm.

FYI, yes, I do have a chip on order. As with any mods that I have done to either automobile, snowmobiles, ATV's or watercraft, I understand that I will be pushing it beyond what it was originally designed to do.

I just believe that from all the posts and all the discussion, and the write up from Sal about max blower rpm. That if you only chip it, you will probably be safe or if you only put a blower pulley on you will probably be safe. But, I would think that doing both, could possibly result in a failure.

Ok, I've probably said more than enough. So now I just gotta say this. Don't be dismantling that L with your GM co-workers and seeing what makes these things tic so that GM comes out with something to exceed to performance of the L. Speaking of which. Is there any secret truck weapon cookin in the design labs that you can share w/us?

BTW, here is location of Sals write up on the blower speed. http://members.aol.com/NLOCsvt/pulleytech.html

 

Peter B. I am glad you understood my comment and had a laugh with me. I thought 4rts2nv's answer was pretty direct. You are one good dude, and he does make a good point. I have never known any of the Big 3 to design anything so close, and most SAE Engineers will build in a 1.5 design factor. Sure we don't know that for sure but it "could be". To it all I say " Go For It" Its your toy and as most men do, we are going to abuse it, aren't we? Good post Peter, see ya around!