GTM Performance Engineering: VQ37VHR Twin Supercharger System

The Dimer · 06-07-2012, 03:42 PM

Quote:

Originally Posted by Mike@GTM

Not really. One of the nice things about designing systems in CAD (like we did with this system), is that things like belt wrap can be calculated to tenths of a degree. With that kind of information, things like load profiles can be modeled and calculated. Granted, there are always variables that cannot be accounted for. That's why we do testing and verification in addition to design work.

By the way, how were you able to determine that there is less than 50% belt wrap on those pulleys? I mean, I know Sam takes great pictures and all, but I'm not seeing less than 50% wrap in the pictures myself.

I can see what he's talking about. If you look at the pictures, the "red" pulley on the left (which has more belt between it and the supercharger pulley than the other "red" pulley) it looks like it could be close to 50 percent. Granted we don't have the CAD drawings to know exactly, and it could just be from the pictures.

Mike@GTM · 06-07-2012, 04:54 PM

Quote:

Originally Posted by Nixlimited

Haha, wasn't able to "calculate" at all. Purely going on visual based on the angle the belts are coming off the wheels in this picture:

In fact, it looks like there is more than 50% wrap. However, what seems clear (thanks to Sam's awesome photos) is that relative to the actual SC pulleys, the stacked pulleys have less wrap. With your single SC systems, you do advertise as a feature the large percentage of wrap, which is what got me thinking about it in the first place.

Anyway, don't want to take anything away from what y'all are doing. The work looks top-notch and I am very anxious to see the results.

Ah, you're referencing the main serpentine belt wrap percentage on the driven side of the stacked pulley. Sorry, I thought you were referencing one of the other pulleys.

First, there is an idler pulley on both sides of the driven side of the stacked pulleys to get as much wrap around them as possible. Also, the driven side of the stacked pulleys aren't as critical in terms of belt wrap as the supercharger pulley itself. The reason for that is the fact that the stacked pulleys are smaller in diameter than the supercharger pulleys. As such, the input torque that the stacked pulley receives from the main serpentine belt is not as large as the output torque at the supercharger pulley. Remember, pulleys are like gears in the sense that a small pulley driving a larger pulley multiplies the torque at the expense of speed (the larger pulley will generate more torque, but turn slower).

A supercharger system with insufficient belt wrap around the supercharger pulley has a tendency to experience belt slip. As you can see in our pictures, we have once again maximized the amount of belt wrap around the supercharger pulley itself.

Quote:

Originally Posted by The Dimer

I can see what he's talking about. If you look at the pictures, the "red" pulley on the left (which has more belt between it and the supercharger pulley than the other "red" pulley) it looks like it could be close to 50 percent. Granted we don't have the CAD drawings to know exactly, and it could just be from the pictures.

Interestingly, you guys are talking about the same pulley, just different ends of it. The end you are referencing does have more than 50% belt wrap. If testing reveals that it needs more belt wrap, we've already got a solution worked out. Like I said in response to Nixlimited's concern, however, it's not as critical as the belt wrap around the supercharger pulley itself.

The Dimer · 06-07-2012, 05:23 PM

Quote:

Originally Posted by Mike@GTM

Ah, you're referencing the main serpentine belt wrap percentage on the driven side of the stacked pulley. Sorry, I thought you were referencing one of the other pulleys.

First, there is an idler pulley on both sides of the driven side of the stacked pulleys to get as much wrap around them as possible. Also, the driven side of the stacked pulleys aren't as critical in terms of belt wrap as the supercharger pulley itself. The reason for that is the fact that the stacked pulleys are smaller in diameter than the supercharger pulleys. As such, the input torque that the stacked pulley receives from the main serpentine belt is not as large as the output torque at the supercharger pulley. Remember, pulleys are like gears in the sense that a small pulley driving a larger pulley multiplies the torque at the expense of speed (the larger pulley will generate more torque, but turn slower).

A supercharger system with insufficient belt wrap around the supercharger pulley has a tendency to experience belt slip. As you can see in our pictures, we have once again maximized the amount of belt wrap around the supercharger pulley itself.

Interestingly, you guys are talking about the same pulley, just different ends of it. The end you are referencing does have more than 50% belt wrap. If testing reveals that it needs more belt wrap, we've already got a solution worked out. Like I said in response to Nixlimited's concern, however, it's not as critical as the belt wrap around the supercharger pulley itself.

Good to know. Thanks for taking the time to explain everything.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
GTM Performance Engineering 370Z SUPERCHARGER KIT PRESS RELEASE	SAM@GTM	Forced Induction	1161	02-16-2014 08:21 PM
GTM Performance Engineering Supercharger CARB kit Test Car Needed	SAM@GTM	Southern California Region	11	11-09-2010 07:02 PM
GTM Performance Engineering Supercharger CARB kit Test Car Needed	SAM@GTM	Forced Induction	26	10-14-2010 02:49 PM