How much boost is a 69mm pulley suppose to make?
69mm VMP pulley...how much boost?
- Thread starter 2014Mustang5oh
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14 to 15ish... If your staying 6 rib, a 15% lower aftermarket balancer coupled w/ a 72mm might be the best way to go. Your running an Aluminator right? Every 5% = roughly 3mm
Why the better route? What about the balancer plus the 69?
Belt slip
So 69 wont grab even tho I have the 90mm idler?
Some discussion about that here.
http://www.svtperformance.com/forums/showthread.php?1078777-2-3-tvs-efficiency-range&highlight=
Seems like it may have issues even with a 90mm idler on there. Might be worth getting Justin@VMP's opinion.
http://www.svtperformance.com/forums/showthread.php?1078777-2-3-tvs-efficiency-range&highlight=
Seems like it may have issues even with a 90mm idler on there. Might be worth getting Justin@VMP's opinion.
He says maybe a little slip but should be fine
Thanks for the info tho. Maybe I'll have a little luck with the 69 and a 90mm I HOPE
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Keep an eye on it for belt dust. I'm honestly not sure exactly where you are supposed to find it but I think it would show up on the snout at least. If it slips bad you'll see it in the gauge on a pull.
A shorter belt, replacing the idler that sits behind the water pump pulley are possible options if you need them. I think corepwn recommended some type of replacement tensioner called a mosaleen.
http://www.mosaleen.com/idler-pulley-systems/
A shorter belt, replacing the idler that sits behind the water pump pulley are possible options if you need them. I think corepwn recommended some type of replacement tensioner called a mosaleen.
http://www.mosaleen.com/idler-pulley-systems/
With a 69mm pulley and stock lower/blower combo I saw 13.5ish PSI. This also had a GT500 throttle body.
Using a 100mm Metco idler I didn't see any slip but honestly I only ran that pulley for MAYBE 2 street pulls before going back to a larger pulley.
Another thing to consider is that the pulley itself is only one of the variables which is why a 69mm will work fine for some and not others.
What I mean by this is that if you're running more boost for a given pulley size for any reason, the friction requirements of the belt become higher on the same size pulley to not slip.
8 rib is the best long term solution, but I stayed 6 rib for now. I calculated and found that by using the mosaleen idler, the amount of belt surface area I'd have with the 6 rib on my 75mm upper pulley would be roughly equivalent to the 8 rib conversion's belt area. After installing this idler I don't see the slip in my datalogs that I had on my test hit at the track at this boost level.
Using a 100mm Metco idler I didn't see any slip but honestly I only ran that pulley for MAYBE 2 street pulls before going back to a larger pulley.
Another thing to consider is that the pulley itself is only one of the variables which is why a 69mm will work fine for some and not others.
What I mean by this is that if you're running more boost for a given pulley size for any reason, the friction requirements of the belt become higher on the same size pulley to not slip.
8 rib is the best long term solution, but I stayed 6 rib for now. I calculated and found that by using the mosaleen idler, the amount of belt surface area I'd have with the 6 rib on my 75mm upper pulley would be roughly equivalent to the 8 rib conversion's belt area. After installing this idler I don't see the slip in my datalogs that I had on my test hit at the track at this boost level.
Corepwn how are you data logging belt slip?
I'm running an 8rib 69mm w/ 5% lower. Only time I get belt slip is on the street if I let traction control pedal the car from a dig... I've had 0 issues, but heard a couple people ran into AC compressor problems.
I'm running an 8rib 69mm w/ 5% lower. Only time I get belt slip is on the street if I let traction control pedal the car from a dig... I've had 0 issues, but heard a couple people ran into AC compressor problems.
I watched my MAF voltage taper off and then fall with compared to RPM in 3rd and 4th gear on my 9.94 track pass. http://i.imgur.com/EVhVtCU.jpg I also have video of the boost gauge dropping 6psi during a pull and you could definitely feel it in the car, ;-)
With the additional idler now the MAF voltage increases linearly as expected with RPM. It actually peaks higher than it ever did even when it wasn't noticeably slipping, it wasn't reaching full potential either.
As you can imagine, I'm excited to get back to the strip with the issues from my first test hit on this setup worked out. (Spinning/Shifting/Slipping) I expect a reasonable gain in both ET/MPH haha.
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I know this is an old post. I’ve been having belt problems for a while and I’m getting ready to go through everything. Right now I’m on a 75mm with 90 mm idler and the Hasty bracket. I just added the heavy duty tensioner and raced one time and belt stayed on. Loaded car in trailer and next day I start the car and there was some knocking and the belt started to walk off of the SC pulley.
So I’m taking it all off and starting from scratch. I debating on going to a 72 mm or even a 69mm . Does the 69 require a shorter belt? Does anyone know where I can order some shims ? I need to get the wobble out of the idler pulley.
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So I’m taking it all off and starting from scratch. I debating on going to a 72 mm or even a 69mm . Does the 69 require a shorter belt? Does anyone know where I can order some shims ? I need to get the wobble out of the idler pulley.
Sent from my iPhone using svtperformance.com
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