You are wrong.

If the ratio was 1:1, you would be right.

The calculation is very simple: Crank / Blower x engine rpm



100 / 70 x 8400 = 12000


I begin to understand when YOU dare to say that there is a lot of misinformation on this site ...

 

Based on the information in this post:
Quote

Opened up the KW kit boxes. Crank pulley is 40 teeth/100mm and blower pulley is 28 teeth/70mm. 8300 rpm red line and 1.428 ratio through the pulleys gives 11,850 rpm on the C38-81 input shaft. Rotrex site says 12,000 rpm is peak input shaft speed.



I was stating that the 150rpm is NOT engine rpm it IS the Rotrex's rpm. The difference between 11,850 and 12,000 is 150. This is what I was stating.

If you use the C38's 7.5:1 ratio and calculate based on the reported "8300rpm" in that quote these are the numbers:
8300(rpm) x7.5(C38 gearbox ratio) x100 (Kraftwerks crank pulley diameter)/ 70 (supercharger drive pulley for 2.2liter)=88928.5714 (C38 blower rpm at 8300 engine rpm). Rotrex states 90,000 MAX rpm.

Yor calculations are NOT wrong. Perhaps I could have been more clear about that part of my reply. (my bad on that one)

The quote that 150rpm is engine rpm IS incorrect.

 

You are right this time.

There are several way to express the same thing.

The fact remains:

Stock pulley on 2.2L(100mm/70mm), engine max speed must be 8400rpm engine = 12000rpm rotrex input shaft.

Stock pulley on 2.0L(100mm/80mm), engine max speed must be 9600rpm engine = 12000rpm rotrex input shaft.

 

Yes...and I agree.

Sorry for the misunderstanding.

 

Problem with injectors solved in 4 days.

Better communication.

Thanks CJ Weidl

 

Incorrect, you were told not to just haphazardly ship the kit back to us without an RMA and when an RMA# was established we would issue a call tag and even ship it back for free, then you requested that we send you the parts to complete the kit, however you wouldn't cancel the chargeback. Not to mention you proceeded to admit that you would keep the kit even if you were issued the chargeback... Are we supposed to give you parts for a free kit?
[/quote]

When Amazon ships something incorrectly they issue an RMA in a day. I gave you and the distributor over a week to figure out the return logistics and then contracted my credit card when it was clear you had no intentions on making good on your promise. I made my intentions clear and you still didn't budge.
[/quote]

Actually just to clarify, we've worked with you every step of the way trying to resolve the issue and trying to give you a number of solutions. As soon as we were notified that you had an issue we contacted KW and began working on a solution for you. You weren't satisfied with anything that was proposed and seemed to change your mind from day to day. I'm sorry you had incorrect parts. Normally, customers will allow us to get the correct part but you were adamant about getting a return on parts you already installed. Thus, we had to contact KW to get approval, an RMA, and a call tag so that you could get the parts returned and we could refund you. I'm not sure where we fell short as we worked to help you out once we were actually notified.

 

Incorrect, we simply provide the customer a great combination for a stock engine. Upper and lower pulleys can always be changed to go for more boost, you will just have to adjust your redline so you are not over spinning the charger. We're getting reports from customers that have installed the kit telling us they are making over 400hp and the dyno tuner wasn't even done yet...

Our pulley combination makes sense:
Kraftwerks: 70mm upper - 110mm lower - 8,400rpm

Has anyone done the calculation on the other kit?
Competitors kit: 90mm upper - 135mm lower - Claimed 8,600 redline at 18psi (?) (we sense some warranty voiding action happening)

Who has the competitors "Race" kit installed, we'd be more than happy to dyno it here at our facility, message, call or email us if you have one. Heck, maybe we can just turn it into a little meet here at our facility!

 

I have ordered it and it should be on the way soon. As for the calculations I have a 2006 with a 2.2 liter and it will be with a 135mm crank pulley ( 2.0 gets a 125mm). I have chosen to order it with a 95mm s/c pulley which will max the blowers speed out at approx 8450rpm (90,059rpm blower speed). One can choose a 90mm s/c pulley which will max the blowers speed at 8000rpm (90,000rpm blower speed).

 

This is the part that contradicts what your saying when you imply that there is plenty of headroom/boost capability with this blower. When you have to lower your redline to not over spin the blower as you say, then its maxed out on our type of motor already. By lowering the redline of the motor, you are not only lowering peak boost back down to where it originally was again as a result, but limiting a key area in the power curve where the F series motor makes the bulk of its power (the top end!) So what you are saying makes no sense. If you have to lower the redline of the motor to not over spin the blower with the next smaller/upgraded pulley, then the blower does not have more room to grow, its maxed out!

All your effectively saying is the result of running a smaller pulley for more power, is its just shifting the higher boost curve further down in the rpm range, which is counter productive to a motor that is most efficient in the upper range. As I said previously, if you had a stroker motor that could only safely rev to say 7500rpm for example anyway, then sure it would make sense to max the blower out at that lower rev limit because that’s where the motor craps out. Capping off a motor prematurely before 8500-9000rpm where our motor makes its peak power, for the sake of the blowers rev limit, doesn’t work, nor can you claim the blower has plenty of headroom to grow. I don’t mean to beat you up, but the story isnt jiving. Am I missing something here? Please clarify if so....

 

Incorrect, you were told not to just haphazardly ship the kit back to us without an RMA and when an RMA# was established we would issue a call tag and even ship it back for free, then you requested that we send you the parts to complete the kit, however you wouldn't cancel the chargeback. Not to mention you proceeded to admit that you would keep the kit even if you were issued the chargeback... Are we supposed to give you parts for a free kit?
[/quote]

When Amazon ships something incorrectly they issue an RMA in a day. I gave you and the distributor over a week to figure out the return logistics and then contracted my credit card when it was clear you had no intentions on making good on your promise. I made my intentions clear and you still didn't budge.
[/quote]

Actually just to clarify, we've worked with you every step of the way trying to resolve the issue and trying to give you a number of solutions. As soon as we were notified that you had an issue we contacted KW and began working on a solution for you. You weren't satisfied with anything that was proposed and seemed to change your mind from day to day. I'm sorry you had incorrect parts. Normally, customers will allow us to get the correct part but you were adamant about getting a return on parts you already installed. Thus, we had to contact KW to get approval, an RMA, and a call tag so that you could get the parts returned and we could refund you. I'm not sure where we fell short as we worked to help you out once we were actually notified.
[/quote]

I think his issue is not with you, but with Kraftwerks, for shipping an incomplete product. In other words, it was not delivered to him as advertised. You're just caught in the middle because you facilitated the transaction, even if you are not at fault for the missing/wrong components.

They have similarly bad reviews on the Miata and FRS forums; someone needs to get it together at KW.