Dumb question... but I know very little about overdrive pulleys, but i'm familiar w/ the concept... I have a vortech v2 T-trim and was looking at a 10-15% o.d... i have a 2.8 6 rib on the blower now and it'll make 16lbs at the peak. I have no power pipe and stock balancer. What kind of boost increases have you guys seen on a 10 or a 15? or a 10/15 w/ a power pipe? i'm guessing a 10% and a power pipe would be a pretty good jump in peak boost, but are there problems w/ the O.D.? like burning things out early since its overdriven? i Know on the mach 1's underdrives are a no no cuz of the high rpm capability and the crank vibrations etc... i was wondering if it was the same on the other end w/ the overdrives...? thanks. -Dylan
10-15% overdrive pulley...
- Thread starter sgtboylan
- Start date
Don't have many answers but have heard your water pump and alt pulley can be overspun. Agin no first hand knowledge.
I would also post in the New Edge Cobra section as many of those guys are running Centri with OD pulleys.
I am also considering an OD crank pulley
Im buying a 10% overdrive for my Cobra. A 10% overdrive is like dropping 2-3 supercharger pulleys down. Its going to be at least 4psi or more depending on if you are using an aftercooler/intercooler. I have a 3.0" pulley on my V1-Si trim and I plan on making 15-16psi with a 10% overdrive. If you use Vortechs impeller speed calculator with my setup I am overspinning my blower by 3000 rpm's at 7000rpm.
Your T-Trim has the same 55,000 RPM limit as mine. If you do a 10%-15% with a 2.8" you are going to be way over the superchargers limit. I would definitely stay away from the 15%. I would be afraid of damaging other acessories.
I did a 8 Rib conversion and my new 8 Rib water pump pulley is much larger than my stock 6 Rib so I will be fine there. I also could use more amps at idle for my stereo system so my 10% overdrive should be perfect for me.
By the way I dont think a V2 T-Trim even exists. V1?
Check out Vortech's Calculator:
http://www.vortechsuperchargers.com/support.php?support_section=Impeller Speed Calculator
Here is a link to your blower and it's RPM limits:
Vortech V-1 T-Trim Supercharger | Vortech Superchargers
Your T-Trim has the same 55,000 RPM limit as mine. If you do a 10%-15% with a 2.8" you are going to be way over the superchargers limit. I would definitely stay away from the 15%. I would be afraid of damaging other acessories.
I did a 8 Rib conversion and my new 8 Rib water pump pulley is much larger than my stock 6 Rib so I will be fine there. I also could use more amps at idle for my stereo system so my 10% overdrive should be perfect for me.
By the way I dont think a V2 T-Trim even exists. V1?
Check out Vortech's Calculator:
http://www.vortechsuperchargers.com/support.php?support_section=Impeller Speed Calculator
Here is a link to your blower and it's RPM limits:
Vortech V-1 T-Trim Supercharger | Vortech Superchargers
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yeah, i was thinkin that too. i looked at the blower rpms and i was a bit freaked... are you cool w/ spinning it that far over? yeah, there is a v2 T-trim... its a send in upgrade from the S trim. i was thinkin about running a 3" or 3.3 that i have w/ the o.d. 10% just to prevent belt slippage and keep boost roughly the same. i just worry about overdriving everything else for durability purposes.
I dont plan on taking my motor to 7000 rpm's very often. I plan on setting my rev limiter at 7K and only taking it to 6800rpm.
At 6800rpm the impeller speed is around 56,000 rpm. If you think about it i'm only taking it to that speed for a split second.
I'm building a 4.75 Stroker and i'm not sure what I should be revving the motor too.
At 6800rpm the impeller speed is around 56,000 rpm. If you think about it i'm only taking it to that speed for a split second.
I'm building a 4.75 Stroker and i'm not sure what I should be revving the motor too.
I've been running at ATI overdrive crank pulley for a while now. I can't tell you how much boost I gained because I changed a lot of stuff when I put it in. I did get an underdrive alternator pulley because I was overspinning mine and it was dropping power near red line. I've heard we can use the underdrive alternator pullies made for the 03/04's if you want to do an 8 rib swap.
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What size overdrive.
Wouldn't getting an underdrive alternator spin it more? The ratio between crank and alternator would increase?
I think it's a 12% overdrive. No. It's underdriven compared to what it was before. Since I went to a bigger pulley the alternator is spinning slower then if it had the stock pulley on it. Like going to underdrive pullies.
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Wrong. You send them your old S trim and they credit you like 800 bucks toward the T-trim.
They used to upgrade them but not anymore since they started selling the Si upgrade.
I run a 3.1" on my Si trim vortech with a 10% overdrive and at 7k engine RPMs am producing 16psi. I do have a 2 valve but the TFS heads and cams I'm running flow just as much if not more than your 4 valve heads. I am also over spinning the blower for a little bit and my tuner didnt say anything unusual about the alternator or water pump.
@ stanger 00: damn. thanks for the info, but you come off a bit abrasive bro... yeah... you send in your S trim and get a T-trim... how is that not a send in? anyway, that neither here nor there.
@ rob: yeah, I won't be getting anywhere near 7K 99.9999% of the time. thanks alot for the comprehensive info. Also, I read your catch can write up... that shit got crazy... haha. awesome write up though. I take it its still good to go?
@ blackdeath and 984now: thanks, i'll definitely look into that.
@ rob: yeah, I won't be getting anywhere near 7K 99.9999% of the time. thanks alot for the comprehensive info. Also, I read your catch can write up... that shit got crazy... haha. awesome write up though. I take it its still good to go?
@ blackdeath and 984now: thanks, i'll definitely look into that.
@ stanger 00: damn. thanks for the info, but you come off a bit abrasive bro... yeah... you "send in your S trim" and get a T-trim... how is that not a send in? anyway, that neither here nor there.
@ rob: yeah, I won't be getting anywhere near 7K 99.9999% of the time. thanks alot for the comprehensive info. Also, I read your catch can write up... that shit got crazy... haha. awesome write up though. I take it its still good to go?
@ blackdeath and 984now: thanks, i'll definitely look into that.
@ rob: yeah, I won't be getting anywhere near 7K 99.9999% of the time. thanks alot for the comprehensive info. Also, I read your catch can write up... that shit got crazy... haha. awesome write up though. I take it its still good to go?
@ blackdeath and 984now: thanks, i'll definitely look into that.
unless his blower is an older blower that was sent in for the upgrade a long time ago before the SI came about. i know a couple people with older V2 T trims.
also unless your bearings were upgraded to the HD (i would hope vortech would do that with the upgrade) your only good for 52k rpm.
best bet is to call vortech and give them your serial number to make sure you have what you think.
The V1 Si Trim is good to 55,000 RPM
I'm not sure about the Legacy model V2-T Trim
Talk to Jamie in the service department at Vortech and he can tell you the info you need.
It's ok to overspin your blower but for a very small amount of time
I'm not sure about the Legacy model V2-T Trim
Talk to Jamie in the service department at Vortech and he can tell you the info you need.
It's ok to overspin your blower but for a very small amount of time
No worries. I was on the iPhone.
True. Forgot that those could be still around.
We're in the same boat. I thought I would have to drop to a 3.0" but my 3.1" worked out just fine for the octane I have here in CA.
Vortech also says you are ok to overspin the blower by ~10% because no matter how efficient the setup is there will be some slip up top. I've been overspinning my V2 Si trim by 5k rpm for 2.5 years now without any issues. In fact I may be pulleying down to a 2.8 soon but lowering my shift point to 6500rpm rather than 7k. This is using a 10% overdrive crank on a H/C/I 2V.
overspinning the blower puts the supercharger out of its efficency range which causes much more heat which isn't good for bearings or anything else. I just returned my 3.0" pulley for a 3.25" pulley and at 7200 rpms my impeller will be at 55500rpms. that way I know im good when rapping my motor past 7K. Im just going to to more compression and not boost so high 
Badd281 is right about the slip. There will always be slip, it is unavoidable. Something I forgot about.
Let's look at it this way. Yes, technically overspinning the blower pushes it out of it's efficiency range but the majority of people running at or just above the max impellar speed are still producing great power with very little heat increase. Seeing as how the 2V really won't make much more power past ~6700 even with the edelbrock intake it is useless to even talk about overspinning when the motor itself really doesn't need to be spun much higher than that in the first place.
I already run a 10% overdrive with 3.12 pulley making 17psi @ 7k rpm. My peak hp is right around 6300rpm due to the stock intake. If I were to switch to the edelbrock intake my peak would probably shift to around 6600rpm. I plan on switching to a 20psi pulley next but lowering my shift point to about 6500rpm that way I will produce more power under the curve, more power at peak, and still spin the blower just as fast as I would have with my setup at 7000rpm. I'd take the higher torque and higher power under the curve with lower max rpm any day.
Oh and to add about the whole comment regarding overspinning and all the extra heat produced. I currently spin my vortech to 58,500rpm at 7k rpm (not taking into account the 10% slip) and have yet to reach over 100 degree intake temps unless I am racing in ~87 degree+ weather. That is with a 3" core intercooler and no meth.
I already run a 10% overdrive with 3.12 pulley making 17psi @ 7k rpm. My peak hp is right around 6300rpm due to the stock intake. If I were to switch to the edelbrock intake my peak would probably shift to around 6600rpm. I plan on switching to a 20psi pulley next but lowering my shift point to about 6500rpm that way I will produce more power under the curve, more power at peak, and still spin the blower just as fast as I would have with my setup at 7000rpm. I'd take the higher torque and higher power under the curve with lower max rpm any day.
Oh and to add about the whole comment regarding overspinning and all the extra heat produced. I currently spin my vortech to 58,500rpm at 7k rpm (not taking into account the 10% slip) and have yet to reach over 100 degree intake temps unless I am racing in ~87 degree+ weather. That is with a 3" core intercooler and no meth.
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Got confused... you were talking about the spin as underdriven..I thought you were talking about a UD pulley for the Alternator...
Makes sense now...
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