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Going from 3.15 to 2.75 Pulley on YSI

 
Old 04-26-2016, 08:12 AM
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venomws7
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Default Going from 3.15 to 2.75 Pulley on YSI

What's up everyone ?

Received the new pulley & dewitt radiator from BLOWNBLUEZ06 (Thanks buddy) a couple of months back and my friend is finally ready to install them

I have a Couple of questions:

Estimated boost gains from the pulley swap?
We are seeing between 17-18psi around 7k rpm

Estimated HP Gains from the pulley swap and going from 91 octane + straight meth to C16 Fuel + straight Meth ?

We're now at 805rwhp with VERY VERY Safe tune with 91octane + Meth
*17 timing high 10s A/F Ratio.
I told him I'm expecting 940-980rwhp with the new pulley, Race fuel/Timing does that seems realistic ??

It's 408ci 9:5 Comp
AFR 225 Heads
Blower cam.
Full Exhaust
6 Speed C5Z

What do you guys think? Any suggestions or recommendations ?

Sam.

Last edited by venomws7; 04-26-2016 at 08:12 AM.
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Old 04-26-2016, 12:35 PM
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Milan
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3-4 psi if I had to guess. I think 950-1000 whp is what you will get...I think the Ysi is way out of its efficiency range with the 2.75 pulley. Still makes good power though...
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Old 04-26-2016, 04:40 PM
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NVTHIS
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I say somewhere between 935-955 rwhp. I say about a 4psi increase.
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Old 04-26-2016, 10:49 PM
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Originally Posted by Milan View Post
3-4 psi if I had to guess. I think 950-1000 whp is what you will get...I think the Ysi is way out of its efficiency range with the 2.75 pulley. Still makes good power though...
What pulleys are in a Ysi's efficiency range?
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Old 04-27-2016, 12:24 AM
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MVP'S ZO6
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I think you will be at 20+ psi and 950+ with pump gas and meth.
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Old 04-27-2016, 03:12 AM
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Originally Posted by Milan View Post
3-4 psi if I had to guess. I think 950-1000 whp is what you will get...I think the Ysi is way out of its efficiency range with the 2.75 pulley. Still makes good power though...
Do you have personal track times to verify this? 2.85 puts the YSI in its sweet spot given the impeller speed on an 8 inch crank. Just looking for racing proof, not dyno's since my C5 trapped very well on 91 pump with a 2.85.
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Old 04-28-2016, 03:59 AM
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Thanks for the info guys looking forward getting the car done.


Originally Posted by MVP'S ZO6 View Post
I think you will be at 20+ psi and 950+ with pump gas and meth.
I wish we had some good pump gas here
With the new pulley we're going with race fuel and hopefully it will help even more with power gains + meth
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Old 04-29-2016, 03:57 PM
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Originally Posted by venomws7 View Post
Thanks for the info guys looking forward getting the car done.




I wish we had some good pump gas here
With the new pulley we're going with race fuel and hopefully it will help even more with power gains + meth
I made 1014 with a 408 and 2.75 ysi at 21 psi.....I think the dyno was a bit happy but I did trap 157 at 3650 lbs race weight ...oh ya...always on c16
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Old 05-01-2016, 03:06 AM
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Originally Posted by c5mtl View Post
I made 1014 with a 408 and 2.75 ysi at 21 psi.....I think the dyno was a bit happy but I did trap 157 at 3650 lbs race weight ...oh ya...always on c16
Auto or manual?
Those are awesome trap speed
I'm sure the owner of the car will be happy with anything over 950rwhp traction will be a major issue with his 18s but we will see how it goes form 3rd gear.
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Old 05-01-2016, 01:58 PM
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lsxvette
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every .1 pully size is 1psi of boost
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Old 05-01-2016, 01:59 PM
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Originally Posted by venomws7 View Post
Auto or manual?
Those are awesome trap speed
I'm sure the owner of the car will be happy with anything over 950rwhp traction will be a major issue with his 18s but we will see how it goes form 3rd gear.
Auto.....I had a couple more mph in it ...one of my pipes blew off at the 1000 foot mark......oh ya that's on 15inch m/t pro radials
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Old 05-03-2016, 02:00 AM
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Milan
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Originally Posted by winters97gt View Post
Do you have personal track times to verify this? 2.85 puts the YSI in its sweet spot given the impeller speed on an 8 inch crank. Just looking for racing proof, not dyno's since my C5 trapped very well on 91 pump with a 2.85.
I know this because I have dyno'd my car a lot with multiple pullies while keeping the rest of the setup the same. Once you hit 2.95/8 the returns are severely diminished.
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Old 05-04-2016, 04:41 PM
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Ksths2
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I was 1010rwhp @ 6500 890tq @ 21psi with a 2.75" - 408 & E85

Last edited by Ksths2; 05-04-2016 at 04:42 PM.
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Old 05-10-2016, 05:25 AM
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Originally Posted by Ksths2 View Post
I was 1010rwhp @ 6500 890tq @ 21psi with a 2.75" - 408 & E85
Compression, H/C/I And trans?
Great numbers
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Old 05-10-2016, 11:43 AM
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10.5:1, LSA, Custom cam, Holley hi-ram - RPM Level 7 4L60e
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Old 05-10-2016, 10:59 PM
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Originally Posted by Ksths2 View Post
10.5:1, LSA, Custom cam, Holley hi-ram - RPM Level 7 4L60e
nice who tunes your car
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Old 05-11-2016, 12:59 AM
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Originally Posted by Milan View Post
I know this because I have dyno'd my car a lot with multiple pullies while keeping the rest of the setup the same. Once you hit 2.95/8 the returns are severely diminished.
I guess that 8 second pass with a 2.75 pulley done below could be accomplished with 4-5 pounds less with a 3.125 that Ksths2 just ran? No, it wouldn't. Your world is on the dyno. Not the track. My 2.85 trapped very well in the 1/8 mile on 91 pump. I'll be interested to see how it runs soon with a new engine.
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Old 05-11-2016, 12:09 PM
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Ksths2
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Speed inc in Chicago
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Old 05-11-2016, 04:17 PM
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robert miller
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The YSI loves the 2.75 pulley if it does not slip on you you going to love it. 21psi and 965 rwhp..
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Old 05-18-2016, 05:41 PM
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Milan
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Originally Posted by winters97gt View Post
I guess that 8 second pass with a 2.75 pulley done below could be accomplished with 4-5 pounds less with a 3.125 that Ksths2 just ran? No, it wouldn't. Your world is on the dyno. Not the track. My 2.85 trapped very well in the 1/8 mile on 91 pump. I'll be interested to see how it runs soon with a new engine.
If we are bench racing trap speeds then what documented trap speed increase have you seen going from 3.125, 2.95, 2.85, 2.75? Do you have this data or are you just conjecturing like usual?

IMO the 2.75 might give a small bump in midrange but I don't see anything posted in this thread that makes me believe there is a noticeable gain over my 2.95.
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