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  1. #1
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    9.0 liter Prefix stroker Gen V Viper vs. Heads/Cam Gen V Viper

    Prefix as you likely know took over for Arrow Racing in the Gen V Viper modding market for whatever reason. As Prefix is the parent company the 9.0 liter stroker motor is now known as the Prefix 9.0 liter (550 cubic inch) Xtreme engine.

    Click here to enlarge

    It's good for 747 naturally aspirated rear wheel horses thanks to the following:

    • Pump gas friendly (93 octane), 10.5 compression
    • Factory engine control system with custom tune
    • Factory intake manifold and throttle bodies
    • Custom Comp Extreme camshaft (Non-VVT) with PAC double springs
    • CNC cylinder heads with 2.125” diameter intake valves with 1.608” exhaust valves
    • Aluminum block with press in cast iron liners
    • Callies “stroker” billet crankshaft, 4.200” stroke with 2.100” diameter rod pins
    • Callies H-beam forged connecting rods with Daido tri-metal rod bearings
    • Mahle custom forged pistons with 0.927” diameter piston pins. Rings are Steel Moly-filled and are 1mm, 1mm, 2mm in thickness

    The car it runs in the video has the standard heads/cam package. The 9.0 liter pulls as expected but not by much. It only has another ~80 whp or so on a Arrow heads and cam setup.

    Is that worth what amounts to roughly a car length by 150 miles per hour for $15k?

    Three sets of brand new 991.2 3.0 headers for sale: Kline, Fabspeed, and Vektor Ceramic Coated

    IPD plenum for Porsche 991.2 3.0 for sale: $650

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    Two badass cars for sure, but an 80WHP difference should translate into a helluva lot more than 1 car length at 150MPH! Something is amiss here...either it's not really an 80HP difference, or the heads/cam only motor Viper is more highly tuned or something (all other things being equal?)???

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    Click here to enlarge Originally Posted by stosh1 Click here to enlarge
    Two badass cars for sure, but an 80WHP difference should translate into a helluva lot more than 1 car length at 150MPH! Something is amiss here...either it's not really an 80HP difference, or the heads/cam only motor Viper is more highly tuned or something (all other things being equal?)???
    We're talking 650+ whp plus levels here. The higher the whp the less the impact of a 80 whp difference.

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    Click here to enlarge Originally Posted by Sticky2 Click here to enlarge
    We're talking 650+ whp plus levels here. The higher the whp the less the impact of a 80 whp difference.
    Feels about right to me... Those are 140+mph cars so 150mph comes up in a hurry. The slow walk away we saw feels about right.

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    Click here to enlarge Originally Posted by Stevenh Click here to enlarge
    Feels about right to me... Those are 140+mph cars so 150mph comes up in a hurry. The slow walk away we saw feels about right.
    About right. I probably wouldn't waste my money no the stroker though after seeing that. Some nitrous though...
    Three sets of brand new 991.2 3.0 headers for sale: Kline, Fabspeed, and Vektor Ceramic Coated

    IPD plenum for Porsche 991.2 3.0 for sale: $650

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    Click here to enlarge Originally Posted by Sticky2 Click here to enlarge
    We're talking 650+ whp plus levels here. The higher the whp the less the impact of a 80 whp difference.
    Ya, I realize that, but an 80HP difference is usually around 4-5/10's in da 1/4 mi...and the old rule of thumb that every 1/10 of a sec=roughly 1 car length is in my head. Soooo, I was figuring a conservative beat down by at least 3 car lengths-IDK? Maybe that doesn't apply in roll racing?Click here to enlarge If that's the actual difference in the vid...think I'm keeping my $15k!Click here to enlargeClick here to enlarge

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    Click here to enlarge Originally Posted by stosh1 Click here to enlarge
    Ya, I realize that, but an 80HP difference is usually around 4-5/10's in da 1/4 mi...and the old rule of thumb that every 1/10 of a sec=roughly 1 car length is in my head. Soooo, I was figuring a conservative beat down by at least 3 car lengths-IDK? Maybe that doesn't apply in roll racing?Click here to enlarge If that's the actual difference in the vid...think I'm keeping my $15k!Click here to enlargeClick here to enlarge
    The rule of thumb for 12 second cars doesnt apply to all cars. As numbers go so do power increase requirements to maintain those splits. These are both high 9 second cars. An extra 80hp isn't getting them another 4 tenths in the 1/4.

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    Click here to enlarge Originally Posted by Stevenh Click here to enlarge
    The rule of thumb for 12 second cars doesnt apply to all cars. As numbers go so do power increase requirements to maintain those splits. These are both high 9 second cars. An extra 80hp isn't getting them another 4 tenths in the 1/4.
    Ya, I've been racing for more of my life than not, and I'm pretty familiar with how HP/speed/weight/etc all works in regards to 1/4 mi times. If you use a 1/4 mi ET calculator you will see that an 80 HP difference between a 600HP car and a 680HP car still works out to about 4/10...but again, I realize that this isn't a 1/4 mi race and other factors can certainly creep into the equation. It's racing-afterall...certainly not worth debating any further.

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    Click here to enlarge Originally Posted by stosh1 Click here to enlarge
    80HP car still works out to about 4/10...but again, I realize that this isn't a 1/4 mi race and other factors can certainly creep into the equation. It's racing-afterall...certainly not worth debating any further.
    They tested the cars in the 1/4 mile and I believe the stroker did do 4/10's quicker.

    The added displacement likely helped off the launch.
    Three sets of brand new 991.2 3.0 headers for sale: Kline, Fabspeed, and Vektor Ceramic Coated

    IPD plenum for Porsche 991.2 3.0 for sale: $650

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    They tested the cars in the 1/4 mile and I believe the stroker did do 4/10's quicker.

    The added displacement likely helped off the launch.
    Ok, so that's what I would've expected for a 1/4 mi outcome (all other factors being equal). Just not sure how 80HP calculates out in roll racing, as I'm not nearly as familiar w/that form of racing...but certainly factors that affect 1/4 mi comparison times between vehicles such as weight/gearing/who gets the jump can also affect roll race outcomes as well. Yes, I realize that these are two identical cars in terms of the model, sooo...these variables should be minimized. However, if one weighs a little bit less, has different gearing/driver mod, or one gets the jump...then certainly results can be skewed just as in 1/4 mi racing.

  11. #11
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    Click here to enlarge Originally Posted by stosh1 Click here to enlarge
    Ok, so that's what I would've expected for a 1/4 mi outcome (all other factors being equal). Just not sure how 80HP calculates out in roll racing, as I'm not nearly as familiar w/that form of racing
    Depends on starting speed among other factors.

    To pull hard at these levels you would need 200+ whp on that Heads/Cam Viper. Plus the Viper is a very efficient platform.
    Three sets of brand new 991.2 3.0 headers for sale: Kline, Fabspeed, and Vektor Ceramic Coated

    IPD plenum for Porsche 991.2 3.0 for sale: $650

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