Those running the Aster Bracket, let me know your pulley/belt lengths
 

HU Pulley.................... Idler Position
Diameter................... Close..... Center.... Far
3.25............................... - ..........50.5?...... 51?
3.4............................... 50.5....... 51.0........ -
3.55............................. 51.0......... -.......... 51.5
3.7............................... 51.5?....... -.......... 52.5?
3.85............................... -............ -.......... 52.5
3.9................................. -............ -.......... 52.5
4.00................................-......... 52.5*........52.6??*
4.13............................... -............ -........... 53?
4.25............................... -.......... 53.5........ 53.5
4.38............................... -.......... 53.5?....... 53.5?
4.5................................. -.......... 53.5........ 54?
4.63............................... -.......... 54?.......... 54?
4.75............................... -.......... 54?.......... 54.5?
5................................... -........... -............ 55.5?

NOTE: with a 4.00/7.65 combo, and a Gates belt that is K080525, I needed to move the idler to the position furthest from the blower. Maybe the belt stretched a little, but in the middle, the tensioner would bottom out, and I got belt slip. -The Alchemist.

Belt Matrix Chart when using the Aster bracket with the CBR 8.65 crank pulley:

3.70 pulley/53.0" long 8 rib belt

3.85 pulley/53.0" long 8 rib belt

4.13 pulley/53.7" long 8 rib belt

4.50 pulley/55.0" long 8 rib belt

http://shop.brutespeed.com/Aster-Aut...er-Bracket.htm

Please let me know if you have found and pulley and belt sizes that are not listed above. Thanks! Bob

this would probably be a good sticky when all of the info is compiled

done.

Aster Bracket with 8.65" CBR crank pulley and 3.7" Supercharger pulley is 53".

Thanks! Bob :cheers:

Thanks, I added it to the link. It will take about ten minutes for it to show up from when I post this, as my website is currently saving the changes. Bob

Aster Bracket, Stock crank pulley size. 4" blower pulley 52.6" belt.

Thanks, I added it on my website, which is currently saving the addition. Bob

aster bracket stock crank pulley 3.4 blower pulley center setting 51"

Thanks! I updated it on my website too. Bob

has anyone done the 8.65 crank with a 3.6 pulley ???

You might try a 52.5" belt. Bob

I'm gonna go with the 8.65 and a 3.7. It's close to what i need. And it will be good when I cam the car too. I just don't want to have to switch belts and shit later on. So the 53 is what I'll use.

Sounds good. Bob

i can't find a 51.5 inch 8-rib belt for the life of me, 7.65 crank pulley and 3.55 blower pulley

Gates makes them.
I've ordered that exact belt length in the past from Jegs.
Part# 465-k080515 HD for the green belt. Drop the HD for just a black belt.
You will have to special order it from them since they don't stock that part #.
I order belts all the time that they don't list.

4.13 pulley with 8.65 crank pulley - Gates K080537HD.

Thanks, I appreciate it! I added it to my website. Bob

Where is the idler placed. Middle or closed to procharger or passenger side

I tried putting my 53 inch belt on with the 8.65 and 3.7 or 3.8 I forgot at the moment and it wasn't even close.

I have the idler in the hole closest to the supercharger.

Anybody running a 4.0 pulley with the CBR 8.65 crank pulley? If so what belt length and what position is the idler. Thanks in advance.

If you find out the info, please let me know. Thanks! Bob

Certainly.

That's a good question, because when I'm ready for some more power, that's going to be the route I go. I just need to get my fueling and intercooler sorted out first before I crank up the blower.

I'm just updating this with some new found knowledge. For a 7.65"/4.00" combo, with a Gates, green belt, 52.5" long, you need the idler in the position furthest from the blower. I have mine in the middle position, and I'm losing boost in the upper rpm range, and finally saw the dust on the bracket last night.

As the rpm's rise, and the tensioner takes up the slack, it will bottom out, and no longer be able to take up slack, so that is why the idler needs to be in the further position to allow the tensioner to take up the slack.

In a perfect world, we'd have belts that wouldn't stretch, but till then, we have the Aster bracket setup to take up the slack when they do.

Good info, thanks! Bob

8.65 cank pulley/ 4.0 pulley - 53.7" long 8 rib belt

Thanks, I appreciate it! Bob

I think this belt might have been a bit too tight. I switched to K080545HD with the Idler in the middle hole and that seems to be perfect.

Thanks for the info, I'll get it added. Bob

After blowing through another set of little pulley bearings in three months I decided to try an experiment.

I bypassed the little pulley by routing a shorter belt underneath it, basically doing SDCE style belt routing. Recently made 580 whp on a mustang dyno without meth with this new setup which puts me right at my no meth 650 whp dynojet dyno with the Aster 7.65/3.4 setup years ago. So it doesn't seem to be giving up much not running the little pulley.

Current setup:
52.5" Belt K080525HD. 8.65 CBR, 3.85" Blower, Idler on Far position, little pulley bypassed.

Previous setup:
53.7" Belt K080537HD. 8.65 CBR, 3.85" Blower, Idler on Middle position, with little pulley.

Max RPMS of the pulleys with 7.65 and 8.65 crank pulleys:

Large Idler Pulley 2.75" Diameter, C=8.64"
With 7.65" Crank Pulley: 24.03/8.64=2.78 @ 6500 engine RPM = 18,070 RPM
With 8.65" Crank Pulley: 27.17/8.64=3.15 @ 6500 engine RPM = 20,475 RPM

Small Idler Pulley 1.75" Diameter, C=5.50"
With 7.65" Crank Pulley: 24.03/5.50=4.37 @ 6500 engine RPM = 28,405 RPM
With 8.65" Crank Pulley: 27.17/5.50=4.94 @ 6500 engine RPM = 32,110 RPM

That is good info, thanks for posting it! Bob

Good info.

Is the 8.65" pulley still available?

Yes it is, I even have one sitting on my desk right now.
http://shop.brutespeed.com/CBR-8RIB8...8RIB865PLY.htm
Thanks. Bob

Good deal Bob.

I might pick it up this spring when I decide I need more power ;) :devil:

Belt
 

Did this belt work out for you? Idler position?
Thanks

Yes. Idler was in the middle hole.

Hey guys
I've got a 4.38 pulley and the cbr crank pulley . Wondering what I should go with for belt length? Bases on 95 1LE post I'm guessing I should be near the 55 range?

From the chart on Bob's Aster bracket page it says a 54.125". Closest Gates I found is a 53.9" K080539HD. There's also 54.5" K080545HD which might work with the idler in the far position. The different idler positions make a big difference in belt tightness. Be sure and let us know your results and good luck.

K080505HD
K080510HD
K080514HD
K080525HD
K080530HD
K080537HD
K080539HD
K080545HD
K080550HD
K080553HD

I had seen some of those, I was looking at the gates RPM line of belts and was basing that off 951LE saying the 54.5 worked for his slightly smaller pulley than mine. I think the next RPM belt size up was 55.14 but I'm worried that will be too big!

Hello All,

I feel lucky to be able to contribute to this thread. Thanks Bob for answering questions via email so promptly. The build is done. Now to the contribution:

Asters + F1X + 7.65/5.25" pully:
This will ONLY fit if you mount the Idler furthest from the blower. The pulley is far too large for any other hole to be used.

55.5" Confirmed working. At first, this belt will go on very tight and fight a bit and just barely slip on, causing the tensioner to lock down between the very top mark and the second top mark.
After you let it idle, and run a few miles, this belt will lock down perfectly just below the second highest mark.

Thanks,
Andy

Edit:

This means, do not go any shorter than 55.5" on above combo. It simply will not fit.

Thanks Andy, I appreciate it! Bob

J Bracket: Aster Bracket using both idler pulleys
Idler Adj Hole: Middle Hole
Tensioner Pos: Exactly in middle location with engine off. Belt tension about a 1/4 turn when twisting belt.

Crank Pulley: CBR 8.65
SC Pulley: ATI 3.9
Belt: Gates K080437HD Green or Gates K080437RPM

Thanks DuWayne!! Bob

Don't know if this is the correct place for this information;

There is debated on the Corvette forum as to which Gates product line to use for the blower belt:

The Gates HD product line is identified with HD at the end of the part number (Gates KO80525HD). The exterior face/side of the belt is green.
The Gates RPM product line is identified with RPM at the end of the part number (Gates KO80525RPM). The exterior face/side of the belt is black.

RPM product line was recently introduced to eliminate belt stretch which is common with the HD green belt.

What members on the Corvette forum report is that the RPM belt is not as forgiving as the HD green belt if the tension is set too tight. If the RPM belt tension is set too tight it will snap compared to the HD green belt that member report does not.

So the consensus if using the RPM belt is to NOT set belt tension too tight.

Aster bracket
CBR crank pulley
4.25 blower pulley
54.5" belt works for me

Hey guys - Could use some belt length help

CBR Crank Pulley
4.38 Blower Pulley

Ive got a 54.5 belt and my tensioner is fully compressed (if looking at the engine bay, the tensioner is as far to the left as can go and is hitting the metal of the bracket)

If i get an half inch longer belt, will I be in the proper working space for the tensioner? Or Should I go with a full inch? I don't want to overshoot it.

My local parts store will let me buy 2 or 3 and bring back the ones I don't use as long as they are absolutely clean..
Its better to be at the higher end of the tension which means the shortest belt that you can and leave
a little room for belt harmonics to move the tensioner..

That should be the correct length, have you run the belt to break it in, as they grow in length?

I have, and its still tighter than can be. Normally id be fine with it, but its so tight when the tensioner actuates i can hear it tapping on the metal bracket (bottoming out) so I think I need to go a bit longer.

A half inch longer belt should certainly take care of it then. Thanks. Bob

Okay bear with me guys - overthinking the hell out of this.

A 54.5 belt (RPM gates belt) has me at 100% tensioner load

The aster bracket tensioner range has an Arc Length of about 1.25inches, and the body the tensioner range is printed on has a diameter of about 2.25inches, meaning an angle of about 63 degrees.

The tensioner swing arm is about 2inches from center of pulley to center of tensioner body, so a 63degree sweep is an arc length of about 2.2inches

Doing some reading - Looks like the guys at gates state that it is "imperative that a belt length is chosen that will put the tensioner at 50% load or less"

So that would be about 1/2 way through the arc length, meaning I need to let the tensioner out about 1.1inches

So I would need a 2.2inch longer belt to achieve that.

Does that seem right? Or completely wonky.

what pulley combo are you running , i have the 8.65 crank and have run a 3.7 3.9 4.13

Running 8.65 crank and a 4.38 on the head unit

What idler pulley positions have you tried? Close - Middle - Far This makes a big difference in belt tension and fitment.

On my current setup I've actually had the adjustment slot machined out and using a ribbed style lock washer to hold it in place. Once the belt tensioner is held at max tension, the pulley can be slid into place and tightened down in place, then the tensioner released right on the max tension mark. The adjustment pulley hasn't budged in 3 months so far and no belt slip at all.

Close doesn't fit with this large of a pulley on the supercharger, and I believe middle doesn't either from what I recall trying to make work - Its only the furthest setting. That sounds dooable, just a lot of work compared to buying a longer belt. Just wanting to make sure my math is right, I dont want to end up with another belt that misses the mark.