Has anyone ran a underdrive crank pulley on a M45? How much did it lower boost? I realize this is not the way to go, but wanting to see.
FU Tuning
What brand pulley?
Also, I'm sure I have a few STOCK pulleys laying around.
Edited 1 time(s). Last edited Wednesday, January 28, 2009 3:18 AM
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
Im not sure, but maybe take this for instance..say if an overdrive crank pulley is 10% larger it adds this much boost, maybe just subtract it? I know not all pulleys will be the same size and not all m45's produce the same boost levels but if you can figure out how much smaller the pulley is you could prolly do some math. I dont see what belt you would use with an underdrive pulley and the sc though, I guess it would work with the stock sc pulley/underdrive crank since many have used smaller sc pulleys and kept the stock sc belt.
The smaller crank pulley will not work with the supercharger. My sisters car had one on it and I tried putting the belt on just so she could get around town till my buddy made her a new stock diameter pulley but it would not go tight at all like I could pull the belt off with my hand and put it on without any tools.
The First Twin Charged jbody
blue car (R.I.P) - 240whp @7psi..
silver car - 305whp 315lbs.tq @15psi (91 Octane) or 420whp & 425lbs.TQ @20psi (94 octane+Alcohol Injection)
All dynos run on a Mustang dyno
Josh F wrote:The smaller crank pulley will not work with the supercharger. My sisters car had one on it and I tried putting the belt on just so she could get around town till my buddy made her a new stock diameter pulley but it would not go tight at all like I could pull the belt off with my hand and put it on without any tools.
I think it will work, but require a different belt, which that part is not that hard top figure out.
FU Tuning
I ran the AEM underdrive pulleys for the crank and alternator....with the stock s/c belt they all fit together......BUT this was before i realized what it would do. Threw check engine lights and hardly made any boost. As soon as i put the stock pulleys back on, saw the 4-5psi that run stock on the M45.
John Higgins wrote:Josh F wrote:The smaller crank pulley will not work with the supercharger. My sisters car had one on it and I tried putting the belt on just so she could get around town till my buddy made her a new stock diameter pulley but it would not go tight at all like I could pull the belt off with my hand and put it on without any tools.
I think it will work, but require a different belt, which that part is not that hard top figure out.
So why go out and buy a smaller belt only to get like 2psi from the supercharger? Why not use a stock diameter pulley and have normal boost? Would be a total waist to have the supercharger on there
The First Twin Charged jbody
blue car (R.I.P) - 240whp @7psi..
silver car - 305whp 315lbs.tq @15psi (91 Octane) or 420whp & 425lbs.TQ @20psi (94 octane+Alcohol Injection)
All dynos run on a Mustang dyno
Ok I think people are not understanding what I'm asking. I was trying to figure out how much boost drop one might see running a underdrive crank pulley. If normal boost for a M45 is 5 on stock pulley and say 8 on a 2.5 pulley would running the 2.5 charger pulley and underdrive crank pulley see 5, 4, 3?? Trying to get a idea.
FU Tuning
How much of an underdrive crank pulley is the pulley? As said maybe reverse what the 10% overdrive pulley adds with the m45 and it may be similar.
Not to be a dick but may I ask why this question was even brought up?
icemike89 wrote:How much of an underdrive crank pulley is the pulley? As said maybe reverse what the 10% overdrive pulley adds with the m45 and it may be similar.
Not to be a dick but may I ask why this question was even brought up?
Someone I know is getting a M45 with a 2.5 on it. His car already has a underdrive pulley on it. He does not want to run the 2.5 (too much heat produced). he also likes the weight of the underdrive pulley, and since it is a hard to find a stock size pulley that weights less than the stocker we were thinking of running the underdrive pulley with the 2.5. I'm thinking the underdrive will off set the 2.5, but wanted some feedback.
FU Tuning
Gotcha, I figured it was something like that. I would say keeping the underdrive crank is not worth it though, as noticeable gains from that would be nothing compared to the sc as Im sure you know. I dont think even the 2.5 pulley is enough to make up for the lower boost levels,plus your spinning the sc faster and building alot more heat without even getting any more boost.
^Not true, lol. A 2.5" pulley spins slower with the underdrive crank pulley than it would with a stock pulley. The 2.5" pulley is there to "make up for the boost" as you say but only in that it spins the supercharger just as quick (or slightly quicker) than stock (with the underdrive).
As for number specifics, who knows, you'll find out when it's on. lol
2001 Olds Alero (LD9)
636 whp / 543 ft-lb
@turboalero
John this is a post from a while back where the stock diameter and 10% over driven diameter crank pulley...plus charger pulley were calculated for boost. I'm unable to find it...but I know it exists.
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
i disagree that finding a stock sized light crank pulley is hard to find.. thats just not true.
mike, how many have you sold you? 200?
RSM's old stock is always on ebay via frankieZ as well...
Needing 2.3 oil pump stuff? PM me...
z yaaaa wrote:i disagree that finding a stock sized light crank pulley is hard to find.. thats just not true.
mike, how many have you sold you? 200?
RSM's old stock is always on ebay via frankieZ as well...
Mike has no more. currently.
FU Tuning
Mastin, has one I believe....
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
Frank has one.
*** correction, frank has more then TEN.
Edited 1 time(s). Last edited Tuesday, February 03, 2009 8:44 AM
Needing 2.3 oil pump stuff? PM me...
^^ are those factory sized.
I think I got an underdrive from him in way back in like 2006.
lol
But, yes, I have 2 of Mike's pullies.
One installed,
One not installed, but is 'supposed' to be put in with the Fire.
-M
Remember....syringes go in the RED waste basket.
I'll have to pick up one and compare.
Asthetically, the clear 'gunmetal' coated one from Mike is hella nice.
And i know fitment is 100% dead on because of his first run.
I remeber the RSM/ZSpec underdrive was the lightest at 12 oz.
But Iwasn't brave enough to test it on the car.
-M
Remember....syringes go in the RED waste basket.
^^^ yes. i know it is because of the picture. its the exact same one i have on my car.
here is a pic of the RSM pulleys side by side....
stock sized left, UD right:
Needing 2.3 oil pump stuff? PM me...
^^ Cool.
Maybe I'll get one to use and place Mike's up on my mantle just cause its so purdy.
-M
Remember....syringes go in the RED waste basket.
from what ive heard, mikes fits more snugly.
however, ive never not once had an issue with either of my rsm's. ill be running the underdrive one once again this summer on my 97z.
Needing 2.3 oil pump stuff? PM me...
Mastin wrote:^^ Cool.
Maybe I'll get one to use and place Mike's up on my mantle just cause its so purdy.
-M
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
does running an overdrive crank pulley make the supercharger spin faster to create more boost with the stock pulley?
also, does anyone know how much boost is added when using the stock 2.8" pulley and an overdrive crank pulley?
01' Z24 5 speed
422whp/400wtq
T4 Turbocharged
Built LD9
HP Tuners
