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  1. #1
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    New Prefix motor

    I've been working with Scot over at Prefix for awhile on a new motor, trying to get a little more power. It's tough getting parts over the last year as everyone knows. A lightweight crank with Callies fell through, but lots of other goodies have gone into this motor. Nothing groundbreaking individually, but hopefully everything combined will be worth 30hp, maybe more? We were a tad over 800whp, 850 was our goal with the lightened crank, so 830-840whp would be awesome. Engine dyno is Thursday, then the motor will get shipped back to me here and we'll run it on the chassis dyno. Thanks to Scot for his hard work on this!
    We did:
    Ligher Mahle pistons
    Lighter valvetrain
    Bigger cam
    Slightly bigger bore (5 more cubes 551")
    a few other small tricks

    41D40736-2E48-4C3D-B885-12F58B581E53.jpg

    6AE83367-6330-4BC4-947E-B8F51D6EBC87.jpg
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  2. #2
    Enthusiast Lawineer's Avatar
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    Nice! Is that a custom made manifold?
    2013 GTS- Black w/ Gunmetal stripes. DSC Tractive Coilovers, ACR sways, carbon stuff, big wing
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  3. #3
    Enthusiast Steve M's Avatar
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    Quote Originally Posted by Lawineer View Post
    Nice! Is that a custom made manifold?
    That's what they all look like...had to go verify the one on mine to make sure. Never really noticed how weird it was in the back, but you never really see the engine from that angle once installed.
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  4. #4
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    That looks and sounds awesome !
    Looking forward to your final numbers !
    Charter Member , SS OHIO

  5. #5
    What was the condition of the 9.0L that you sent back for refresh? When the took it back down ti the block did it look good? Was the overbore for cyl taper/out of round?

  6. #6
    Enthusiast Lawineer's Avatar
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    I’m surprised you’re not running sheet metal manifold. Is it a clearance issue?
    2013 GTS- Black w/ Gunmetal stripes. DSC Tractive Coilovers, ACR sways, carbon stuff, big wing
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  7. #7
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    Fantastic Cable. Can't wait to hear the results. I hope it get 850 .
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  8. #8
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    This is exciting!
    Nick Anderson

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  9. #9
    This sounds incredible. Cant wait for the final nums and how she sounds.

    BTW what did losing out on the lightweight crank and Callies cost in terms of performance left on the table? Higher revs/hp up top?

  10. #10
    Enthusiast Lawineer's Avatar
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    Quote Originally Posted by Snakebit10 View Post
    This sounds incredible. Cant wait for the final nums and how she sounds.

    BTW what did losing out on the lightweight crank and Callies cost in terms of performance left on the table? Higher revs/hp up top?
    I'm going to venture a guess that he was limited by airflow and/or valvetrain limitations on a pushrod engine before the bottom end.
    2013 GTS- Black w/ Gunmetal stripes. DSC Tractive Coilovers, ACR sways, carbon stuff, big wing
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  11. #11
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    Nice!
    I am envious! That would be amazing!

  12. #12
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    Quote Originally Posted by SRT_BluByU View Post
    What was the condition of the 9.0L that you sent back for refresh? When the took it back down ti the block did it look good? Was the overbore for cyl taper/out of round?
    We had a small valvetrain piece fall into the block after 3 years of hard use. It put a tiny hole in the block, not much damage, just two pistons which we were replacing anyway.
    The bigger bore is just to get 5 more cubes, 6-7hp and 8 ft/lbs maybe.
    Follow my Instagram- @9literviper 2013 track car, 2016 ACR, 1996 GTS, 2001 RT/10, 2003 SRT/10

  13. #13
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    At the level that you're at, is the thinking that 840whp equates to measurably quicker lap times than 800whp? Generally, increasing HP is great for roadcourse cars, but there is a limit and, after that, lap times just do not decrease any further with more power (unless you start running longer tracks). I have to think that you're at, or very near, that limit with 800whp (nearly 900hp crank) for a roadcourse Viper. When the ACR-E was announced, I expected the optimal setup to be slicks, max downforce settings, and approx. 750whp for your typical American roadcourse. I can see it being more fun to drive, but I am curious to see if lap times can continue to improve. Keep up the amazing work because we're all anxious to see what these beasts are truly capable of!!

  14. #14
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    Quote Originally Posted by Lawineer View Post
    I’m surprised you’re not running sheet metal manifold. Is it a clearance issue?
    We can't find anyone that would make just 1. Would have to be at least 10 or so for big bucks for the best guys to be interested. this guy would make some, but he needs at least an order of 10-
    https://www.instagram.com/shaunscustomalloy/
    Scot has talked to Kinsler as well, but it hasn't worked out.
    Follow my Instagram- @9literviper 2013 track car, 2016 ACR, 1996 GTS, 2001 RT/10, 2003 SRT/10

  15. #15
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    What's the compression ratio?
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  16. #16
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    Quote Originally Posted by Scott_in_fl View Post
    At the level that you're at, is the thinking that 840whp equates to measurably quicker lap times than 800whp? Generally, increasing HP is great for roadcourse cars, but there is a limit and, after that, lap times just do not decrease any further with more power (unless you start running longer tracks). I have to think that you're at, or very near, that limit with 800whp (nearly 900hp crank) for a roadcourse Viper. When the ACR-E was announced, I expected the optimal setup to be slicks, max downforce settings, and approx. 750whp for your typical American roadcourse. I can see it being more fun to drive, but I am curious to see if lap times can continue to improve. Keep up the amazing work because we're all anxious to see what these beasts are truly capable of!!
    It's a huge difference, on any track. The big boys that I compete against that have 1200+hp are EIGHT seconds faster than me. My turbo car should be similar, at least 8 seconds faster than this car. You are taking SECONDS off each straight, even small ones. With slicks I can put the power down at very slow speeds, so much less bog with more power. A good example is East track here at Bondurant/Wild Horse Pass. It's 1 mile, basically an autocross track. My bone stock ACR on slicks is 57.7, this car is 54.4. With 840whp I'll be 53.7 ish

    More importantly than just faster mph on the straights with more power, having more power lets you keep increasing downforce as you can overcome the drag. My wing is now at #4 setting and have Doug Shelby's extended splitter. Take a look at the downforce on the Unlimited Time Attack cars, it's ridiculous they can run all they want and never worry about the drag

    Check out LYFE's new twin turbo C5-
    https://www.instagram.com/p/CVB-vP4FMjp/
    https://www.instagram.com/p/CVvVww6FKhD/
    Last edited by Arizona Vipers; 01-19-2022 at 09:30 AM.
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  17. #17
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    Quote Originally Posted by TBSH View Post
    What's the compression ratio?
    12.75 to 1
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  18. #18
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    Quote Originally Posted by Arizona Vipers View Post
    We can't find anyone that would make just 1. Would have to be at least 10 or so for big bucks for the best guys to be interested. this guy would make some, but he needs at least an order of 10-
    https://www.instagram.com/shaunscustomalloy/
    Scot has talked to Kinsler as well, but it hasn't worked out.
    If he could make a Gen V styled one run on my Comp Coupe, I'd be in for one.
    Nick Anderson

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  19. #19
    Why didn't it work out with Callies?

  20. #20
    Quote Originally Posted by Arizona Vipers View Post
    We can't find anyone that would make just 1. Would have to be at least 10 or so for big bucks for the best guys to be interested. this guy would make some, but he needs at least an order of 10-
    https://www.instagram.com/shaunscustomalloy/
    Scot has talked to Kinsler as well, but it hasn't worked out.
    wow.. engine jewelry for sure!

    - - - Updated - - -

    Quote Originally Posted by Arizona Vipers View Post
    We had a small valvetrain piece fall into the block after 3 years of hard use. It put a tiny hole in the block, not much damage, just two pistons which we were replacing anyway.
    The bigger bore is just to get 5 more cubes, 6-7hp and 8 ft/lbs maybe.

    hold in the block or pistons? Did you need to weld and re-sleeve? was it a rocker arm bolt that backed off or valve retainer?

  21. #21
    Quote Originally Posted by ViperC View Post
    Why didn't it work out with Callies?
    I'd bet on it being because Callies couldn't get their hands on the raw materials / round stock / etc that they needed for the crank.

    Dupont had a nearly 6 month national backorder on (at least) one of their Molykote greases. They told us they simply didn't have the raw materials necessary to make it.

    Running through a similar issue with another company being out of 316/316L and they can't get a firm date from their vendor on resupply.
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  22. #22
    Enthusiast Lawineer's Avatar
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    Quote Originally Posted by Arizona Vipers View Post
    We can't find anyone that would make just 1. Would have to be at least 10 or so for big bucks for the best guys to be interested. this guy would make some, but he needs at least an order of 10-
    https://www.instagram.com/shaunscustomalloy/
    Scot has talked to Kinsler as well, but it hasn't worked out.
    Really? That's the whole freaking point of a sheetmetal intake manifold- you can make just one, lol. You dont need a whole cast/die, etc.
    I can't help but think a lot of power is left on the table using factory manifold. Optimizing the runner lengths is a really big deal for making big power NA.
    2013 GTS- Black w/ Gunmetal stripes. DSC Tractive Coilovers, ACR sways, carbon stuff, big wing
    2014 BRZ: Race/track car. Full retarded. 2016 Lexus GX460: Full boring

  23. #23
    It's going to be awesome to see what the engine dyno reads vs the chassis dyno. We may settle the debate once and for all that the drivetrain loss is less than 15%. That's always been the "rule of thumb" but I think it's less than that with the modern drivetrain.

  24. #24
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    Quote Originally Posted by Whiskey View Post
    It's going to be awesome to see what the engine dyno reads vs the chassis dyno. We may settle the debate once and for all that the drivetrain loss is less than 15%. That's always been the "rule of thumb" but I think it's less than that with the modern drivetrain.
    Much closer to 8-10% now.
    Nick Anderson

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  25. #25
    Wow! Very cool!
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