Seems like every Viper turbo kit out there puts the turbo above the muffler. That places the turbo at the end of about 4 feet of exhaust that is being cooled by the snow spray in the tunnel. That can't be great for throttle response? No one seems to be talking about this.
Viper Turbo Location
- Thread starter Hornet
- Start date
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BigFish BC
Well-known member
well my nytro motor is done up just a bit
cams porting valves,pistons rods & it spools so fast it has sent a few people off the back of the sled
it has no noticeable lag at all,the only vipers i have rode are the boost it ones & they run no shim & are very close throttle response wise to my nytro.i cant speak for the other kits but i was very impressed by the boost it kit, no lag that you could notice.the reason everybody is putting the kit there is cost savings,you could do a center mount but would need a fuel tank & header adding 2000$ too the kits.
cams porting valves,pistons rods & it spools so fast it has sent a few people off the back of the sledit has no noticeable lag at all,the only vipers i have rode are the boost it ones & they run no shim & are very close throttle response wise to my nytro.i cant speak for the other kits but i was very impressed by the boost it kit, no lag that you could notice.the reason everybody is putting the kit there is cost savings,you could do a center mount but would need a fuel tank & header adding 2000$ too the kits.
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stingray719
Well-known member
Back when I got my first boosted Phazer it was an MCX 160hp? kit. Had about a second or more of lag and everybody I talked to including an MCX dealer said it was lag from head shim. Having raced low compression (9to1 rule) stock cars I found this explanation unacceptable.
So I started looking and found the secondary on a 2007 Phazer was basicaly the same secondary that was on the old 45hp 2 stroke Phazers of yore!! LOL, how did anybody expect a secondary designed for 45 hp to handle 160hp? So I put a secondary off an old SRX on it and NO MORE LAG!! Did the same thing to the Supercharged Phazer with same results (not lag but too quick upshift problem solved).
You might have turbo induced lag, but check clutcing first. Too much power for secondary settings causes too quick an upshift and creates lag.
Any Phazer guys still out there running boost ping me, set up right your boosted Phazer will lift the skis on takeoff.
So I started looking and found the secondary on a 2007 Phazer was basicaly the same secondary that was on the old 45hp 2 stroke Phazers of yore!! LOL, how did anybody expect a secondary designed for 45 hp to handle 160hp? So I put a secondary off an old SRX on it and NO MORE LAG!! Did the same thing to the Supercharged Phazer with same results (not lag but too quick upshift problem solved).
You might have turbo induced lag, but check clutcing first. Too much power for secondary settings causes too quick an upshift and creates lag.
Any Phazer guys still out there running boost ping me, set up right your boosted Phazer will lift the skis on takeoff.
Yes, the response with or without a headshim is better the Nytro.
Decreased throttle response does not come from lowering the compression ratio (head shim) as long as valve timing is adjusted accordingly. I ran a shimmed Nytro engine normally aspirated for a few days and throttle response was as good as stock. Lack of throttle response, or lag, really becomes apparent when the distance between the head and turbo (length of exhaust) increases.
well my nytro motor is done up just a bit
I realize that mounting the turbo closer would require more expense and custom parts. I would just like to know how the lag has just magically "disappeared" for Viper turbos.
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stingray719
Well-known member
Just go ride one..............
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Deep Powder Guy
Banned
On my old Apex with a garrett mounted on the clutch side Turbo to Intake was pretty close to 4 feet with no lag issues.
DPG
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BigFish BC
Well-known member
iam not a motor guru but i can tell you the motor sounds diff than a nytro motor,so they may have changed something internal.i really thought there would be some noticeable lag but there was none.i can tell you i have never rode a rear mount turbo i liked,have owned 4 front mounts & the viper spools as fast as any of my front mount kits did.
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Deep Powder Guy
Banned
iam not a motor guru but i can tell you the motor sounds diff than a nytro motor,so they may have changed something internal.i really thought there would be some noticeable lag but there was none.i can tell you i have never rode a rear mount turbo i liked,have owned 4 front mounts & the viper spools as fast as any of my front mount kits did.
They still make rear mounts ? I remember like it was yesterday the MCX rear mount on the RX1 don't laugh but I was a rocket in her time. If you rode it enough the lag goes away "Mentally".
I don't think there's a quality turbo front mount kit on the market that "lags" anymore unless it setup incorrectly. Lag is long gone and that's good for the turbo guys.
DPG
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stingray719
Well-known member
iam not a motor guru but i can tell you the motor sounds diff than a nytro motor,so they may have changed something internal.i really thought there would be some noticeable lag but there was none.i can tell you i have never rode a rear mount turbo i liked,have owned 4 front mounts & the viper spools as fast as any of my front mount kits did.
Agreed, I rode 3 diff demo sleds in South Dakota Yamaha Demo and it was hard to tell when the turbo spooled it was so smooth.
What do you attribute the difference in the 2 sleds to?
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Evolution Powersports
Well-known member
Turbo sizing, turbine housing A/R, etc have a profound effect on turbo response. Agreed that the cold pipe makes a turbo system less responsive than it could be.
I'm a little too lazy to calculate exact numbers, but here's some numbers to think about. 5' of 2" tubing is .11 cubic feet. The exhaust flow of a 1050 cc engine at 8600 rpm at atmospheric pressure (we're talking lag so this is pre boost) with at exhaust temp of 1100 (guess) is 436 cfm. So to fill 5' of exhaust pipe takes 1/66 of a second.
Now lets say we have a clutch engagement of 4k rpm and recalculate it. that's 204 CFM of exhaust and would take 1/31 of a second to fill it...
Just some numbers to think about when considering header length.
Rick Coffman
Now lets say we have a clutch engagement of 4k rpm and recalculate it. that's 204 CFM of exhaust and would take 1/31 of a second to fill it...
Just some numbers to think about when considering header length.
Rick Coffman
