After going from a serp belt set up , to a cog pulley and belt set up . I've noticed and realised a few things. Below is a comparison of both the serp belt and cog set up at each rpm level . I only had one logged run with the cog system to compare , before tearing up the small belt on the blower . But it shows where the problem with building boost with a serp pulley system is .


serp belt PSI........... RPM .............cog belt PSI


not logged ...............3000 ................4.1

4 ............................3500 .................5.8

7 ............................4450 ................10.5

9 ............................4900 .................13

12 ...........................5600 ................15.1

13 ...........................5900 ...................17

slipage ....................6150 .....................18.1
13 to 14 psi

With the serp belt system , the pullys I had on [ 3.12 and 34 tooth cog ] should have made more PSI than the pulleys I have on now with the cog system [ 32 tooth = 3.12 and a 32 tooth on blower side ]

But as you can see the cog system made far more PSI at every RPM level . On average...4 PSI more for every rpm level . This can only be from belt slipage . It basicly shows that the Vortech SCer serp belt is slipping all the time . Ive always asked my self...why the stock system couldn't get near the 20psi they say the blower could make .The above comparison of both answers that question . Running the belt as tight as you can get it and or re-routing the belt system to get a little better grip . Will only help slightly.


As of right now . I have a bigger blower pulley coming [ 30 tooth...stock is 28 tooth ] and see what that will make . If it keeps the boost down to around 16psi . I'll tune it there and run it for a while . A new EMS isnt in the budget right now , so we will see .

 

yeah that's interesting, but i'm kinda curious how you can say re-routing the belt will only help slightly when you never rerouted your belt on the stock blower or the T-trim?




the rest of us who have rerouted the belt have found that the belt no longer is slipping when graphed on a boost chart and we don't have to tighten the crap out of the belt anymore

besides, how can you really know how much the blower is turning compared to before? It's a totally different belt and pulley setup. With that new Cog setup, maybe you're overdriving the blower more than before?


are you basically saying that using the cog system for even the stock 8 psi setup will magically raise the boost 40%?
That just might be true for your specific cog system with how the pulley diameters and belt sizes are setup, but I'm not so sure how a toothed belt will raise a low 2 psi up to almost 3 psi from the belt alone when 2 psi isn't all that much load on the belt

 

Well ..I'll tell you what . You send me your stock blower and I'll put it on my cog pulleys system . Then we can compare PSI levels . You can keep your 2.87 pulley on and I'll run it with what is on it now [ 3.12 = 32tooth ] And I bet I make far more PSI with the same blower as you do with the 2.87 . I'll put my money on it . And when it does...will that prove to you that the serp pulley system is basicly always slipping ?

 

SInce you have re-routed your pulleys and belts....do you make more psi at all rpm levels ? If so how much ? got a comparison ?

 

I make 12 psi where before I was slipping at 10 psi. The boost was otherwise the same below 10 psi

and no I'm not going to take off my blower and ship it off for the sake of a test on your cog setup that no one else has
believe what you want though

 

Vortech says the stock blower can make 20psi . With a 2.87 pulley you are spinning the blower [ if the belt didnt slip all the time ] at over the 53,000rpm level they suggest . At 53,000rpm you should be making the full 20 psi the blower can make . Explain to me why you are not making any where near 20psi then ?

 

While I think having a cogged system would help with the slippage issue, it may be the wrong way in the end. With the belt slipping, at least you can still run the car even if you are not boosting as much as you'd like to at a given RPM level. If you went with a strictly cogged setup and the belt no longer has the ability to slip, if something happens and eats the teeth due to too much tension, your car is now undriveable.

 

Could be one reason why Vortech won't warranty anything past the 3.12 pulley.

 

WHY DO YOU LIKE TO discredit every one elses thoughts and theories...unless you think of them first ?

Think about it SENTRY...Pulleys are pulleys . The same size pulley should produce the same boost level .

The Serp pulleys are NOT grabbing all the time . The serp pulleys are slightly slipping all the time . Its not rocket sience SENTRY...you just like to argue

NOW PLEASE...go find some one else to argue with !!!!!!!!!!!!!

And do not post in this thread again . You always wanting to argue is getting old DUDE !

 

I understand what your saying . The cog system I have is seperate from the serp pulleys that run the rest of it . So if a belt breaks and or hte teeth get ripped off the car still has every thing else .

 

no it's not "rocket sience"
it's engineering


The psi reading we're talking about is in the actual blower and not the manifold

a bigger engine would be capable of sucking in more air, creating more pressure in the blower as the additional air gets compressed. That maximum 20 psi for the S-trim is the maximum pressure that blower can hold before it starts choking

The maximum impeller speed is how fast vortech claims it can spin before it goes out of their design parameters and cause damage, be it long or short term

On their website, it says "Fits engines up to 680 horsepower" for the S-trim and "Fits engines up to 825 horsepower" for the T-trim. They're talking about the NA engine the blower can be mated to, not the power you can expect from the blower. They probably reached those figures based on the compressor map and what the maximum limit the blower can handle with its internal psi (20psi for the S-trim's case)


vortech says the S-trim outputs a maximum of 1000 CFM, probably at the maximum 50k rpms with a 680hp engine
I don't have a way to measure CFM so I actually have no idea how close my S-trim is to being maxed out, but I suspect it has a LOT of headroom left in it
it's pretty much ok to overdrive the blower a little as long as the blower doesn't go above 20 psi of pressure and/or output more than 1000 CFM



I do agree that the cog belt setup will have less slippage, but I don't think it becomes a big deal until the belt starts reaching a certain amount of load

The T-trim is already putting a way larger load on the belt than the regular S-trim, so I'd think in your case with a T-trim, going from the bone stock belt system to the cog setup probably would help a lot more than someone running the stock kit wit 8 psi at redline

Do you really think someone with a stock kit would get 0-4 more psi by changing to a cog setup?
I'm just asking questions. I think the T-trim blower is probably too big of a blower for the Z engine, which is normally mated to engines twice as large like the LS2 and LS7
Vortech even mated the LS1, LS6, LT1, mustang, and mustang cobra engines to an S-trim

My theory why you suddently gained so much more boost is the T-trim was always causing the bone stock regular belt setup to slip a lot, but I think it's a different story for the S-trim which isn't nearly as strong. I'm basically agreeing with you completely in regards with running a T-trim on a VQ35
I'm just skeptical it's an identical situation for the S-trim

 

nice

 

Vortech web site says . That the blower for the stock G35...350Z kit will produce 20psi . That PSI should be produced at 53,00rpm blower speed . If a 2.87 pulley is put into Vortechs calculator for blower speed .[ cant remmber exact rpm ] it is spinning the blower at or above the 53,000rpm level at the motors redline . Add in a intercooler with a 1psi drop and the difference of PSI at the blower and the PSI at the manifold...isnt that big..maybe 1 to 3 psi max ? So if the 2.87 pulley can only make 12psi, the blower must not be spinning as fast as the diameter of the pulleys would suggest it should be . Which means the serp pulley is slipping . Now if the boost rose to 12 psi very quickly...say 5000rpm motor speed . Then flattened out the rest of the rpm range . I would say that the serp belt doesnt slip until a certain rpm level . But as soon as there is some load put on the blower [ my guess 1 to 3psi ] the serp belt starts to slip slightly .

 

Another arguement was something about a bigger motor .

With the smaller V6 motor we have . The blower will reach 20psi sooner if the belt didnt slip because of the motors not capable of pumping as much air as a bigger motor would be able to . SO the boost will build [ back up ] sooner .

 

how would a smaller engine make the blower reach 20 psi sooner than a bigger engine. That's backwards.

A bigger engine sucks in more air which all has to go through the supercharger that spins at whatever rpm to compress to whatever psi

 

the S-trim says the maximum rpm is 53k rpms
the T-trim says the maximum rpm is 55k rpms


that's the max that the blowers are capable at spinning at, not the rpm the G35/Z kits spin at in stock form at redline
I think they spin at like 46k or something around that at 6600 rpms with the 3.33 pulley

 

Geeeez think about it Sentry ?

Take a blower seperate from a motor , spin it at the same rpm ...now put a V6 at the end of that blower running at WOT . The boost will build faster because the V6 isnt capable of pumping as much air as a V8 will . Its the same theory of running a open exhaust as compared to a restricted exhaust . You will be able to make more boost with a less flowing exhaust . And an open exhaust will run less boost but make more power...SAME THEORY....ARGUE SOMETHING THATS TRUE WILL YOU ? listen to my earlier post....DONT POST AGAIN PLEASE !!!!!!

Again your arguing a point that isnt true , just to be arguing

 

you're talking about psi in the intake manifold, not the blower

it's a different story inside the blower


but yeah I know, I've been saying for a very long time now that going with a bigger engine will lower boost pressure (in the intake manifold) with the same blower setup
however, it will raise boost pressure inside the blower



here's some scenerios:

LS7 and S-trim = 4 psi manifold pressure and maybe something like 15 psi in the blower
VQ35 and S-trim = 8 psi manifold pressure and something like 7.5 psi in blower
civic engine and S-trim = 14 psi manifold pressure and maybe around 5 psi in the blower

















you need to lay off the emotional outbursts.

I'm responding to what you've claimed based on my understanding of superchargers and engines. This isn't an argument to me, this is an open discussion where we try to pool all of our knowledge and ultimately try to come away with everyone learning something they didn't know before. And that is how progress will ultimately be made

If you started a thread called "I saw a pink airplane, so all airplanes must be pink" and I disagreed with you, it's kinda lame listening to your outbursts where every 2 posts you say I'm arguing just for the sake of it and to stay out of your thread. Kids act like this when they don't want to share toys with each other, but want to play with everyone else's - get what I'm saying?

I appreciate you starting this thread - I think I read in another post where you posted the side by side boost log comparison. And it is interesting how much power you gained from the cog setup. I think there's some different circumstances from your old setup vs mine or other people with the S-trim and rerouted belts. You have a really powerful blower and were previously running it on the stock belt system that's the most prone to slipping. It's a different situation than an S-trim with a rerouted belt setup

I think you made the right move switching to the cog setup for your T-trim. It would suck though if you snapped the belt when driving because those sort of belts don't have any give, they just snap, where the regular belts will slip too much stress is put on them

 

The shock loads imposed on the blower drive train by a timing belt need to be evaluated by many hours of use to simulate street use if that is the intended application or less obviously if it is a drag race application. A V-belt design while always permitting some degree of slip does provide a lot of cushioning to the drive components. That is why you don't see timing belts on many supercharger kits. As a matter of fact you don't normally see timing belt used for anything that doesn't require precise timing because of the advantages of built-in slippage. If the size of all timing belt drive components were increased to a size capable of handling the shock loads it may be a different story.
I do however believe this R&D is a very worthwhile project to explore the practical limits of timing belts.

 

LS7 and S-trim = 4 psi manifold pressure and maybe something like 15 psi in the blower
VQ35 and S-trim = 8 psi manifold pressure and something like 7.5 psi in blower
civic engine and S-trim = 14 psi manifold pressure and maybe around 5 psi in the blower

Your taking a huge guess and you have no idea what preasures would be .

The fact is..the preasure at the end of the blower and whats in the plenum isnt going to be a huge gap as you are trying to state. Thats why IC company's claim a 1 psi drop in preasure