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Considering Whipple 2.9

Discussion in 'SVT Shelby GT500' started by weider1717, Aug 2, 2019.

  1. GT Premi

    GT Premi Well known member Established Member

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    Wouldn't that be an argument for running a smaller pulley on the bigger blower, though? To put it into its efficiency range quicker? You can run a 2.8" pulley on the Whipple 2.9 on pump gas. For the '11/'12 GT500, you can run up to 21psi of boost on pump gas. I'm sure running a 2.8" pulley would nearly eliminate any advantage the smaller TVS has. I still stand behind my statement that a 2.4" - 2.6" pulley on the Whipple 2.9 would destroy a TVS running the same size pulley. Only problem with the Whipple there, though, is that you'd have to convert to E85 or race gas full time with a pulley that small.
     
  2. Catmonkey

    Catmonkey I Void Warranties! Premium Member Established Member

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    That's my point. To get the larger supercharger to operate more efficiently, you need to spin it harder to get to it's adiabatic efficiency range. Adiabatic efficiency has more to do with how efficiently the blower is compressing the air, as opposed to just how much air it moves. The problem with running 21 psi on pump gas is how much ignition timing you're going to have to back out to keep the engine from detonating. Boost adds power, decreased timing takes it away. You can do it, I just think most people believe it's safer to run 17-18 psi on pump gas and time it accordingly.

    Let's look at it this way. Take that graph I posted, 2.3 and 2.8 are the number of liters of air the supercharger moves with one revolution of the drive rotor. I know the TVS has a 2.4" upper pulley. Given that, the TVS should theoretically be moving something like 1,441 cfm of air at 6,000 engine rpm. I'm going to assume the KB had a 3" upper pulley, since that is what KB sells for 93 pump gas applications. They sell them in 1/4" increments, so it's a safe bet. Given that upper pulley size, the KB would be moving 1,403 cfm of theoretical airflow at the same 6,000 rpm range. Granted the TVS has a ~2% edge on theoretical airflow, but they're closely matched in terms of how much air they theoretically move at similar rpm. Now look at the boost each makes throughout the rpm ranges. The reason the TVS is making more boost at all rpm ranges below 6,500 is it has better adiabatic efficiency than the KB in that range. 4 psi more boost is pretty significant from 3,000 to 4,000 rpm and it clearly shows the KB is outside of its efficiency range. Either it's not effectively compressogn air and/or using too much power to drive the supercharger. After 6,000 rpm, the TVS has fallen out of its adiabatic efficiency and the KB is just getting into its effective range. If you didn't have an engine limitation at 6,500 rpm, you'd see that gap get further apart.

    I can assure you a 2.9 Whipple isn't going to act a whole lot different. The results just get more bizarre, the bigger the blower. If anyone is following the dynos on the 2.65 Gen 3 TVS on pump, you'll notice a drop in boost in the lower rpm range for that blower over the 2.3. There's a reason the bigger blower manufacturers only focus on "peak" horsepower. The KB made 29 more hp at the peak than the TVS, but the TVS made 26 more average horsepower between 4,000 and 6,500 rpm. The TVS made over 60 more hp at 3,000 to 4,500 rpm than the KB. Now, that's power you're going to notice on the street. So if you only focus on peak, the KB would seem to be the better blower for an otherwise stock application on pump gas. Now let me emphasize that these were different dynos on different days. All I can guaranty is that they both occurred in Florida, so the altitudes weren't that different.

    Now if you want to throw more octane into the mix and/or more cam timing to increase the engine's ability to utilize greater quantities of airflow, you will need to spin both blowers higher to push the limits of boost and/or octane, which will leave the little 2.3 further behind and that adiabatic efficiency will occur much lower in the power band. By the same token, it will push the KB further into the territory where it's using more of its adiabatic efficiency. If you follow @biminiLX's engine build with his ported 2.3 blower, you'll really see what happens to the little 2.3 when you step up the engine's power and airflow capabilities.
     
  3. weider1717

    weider1717 Member Established Member

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    I agree with the above I know they can be made to whine but you have to run such a high boost it puts you in the BMC club I believe it's call on here, lol.

    Anyone up on the Whipple gens? I get confused when I visit their site they have several for the GT500 what is the latest Gen that is out for these cars? Also I watched a video where it was said they're releasing or already realeased a ten 5 and plan to release ten 6 soon not sure if that is for our cars or not though.
     
  4. tvspower

    tvspower Active Member Established Member

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    Thanks. Very interesting
     
  5. Tob

    Tob Salut! Staff Member Super Moderator

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    Well said cat.
     
  6. tvspower

    tvspower Active Member Established Member

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    Cat monkey give me your op on my setup, please
    Built 5.4 ,BPS cams ,ported vmp gen1 n elbow, etc
    Psi 15lbs....upper 2.5. lower 15%.
    Very conservative 91 tune......
    Built is good for 1200 hp I'm told,
    Which new blower for street/highways
    Now 682whp. 727wtq
     
  7. Catmonkey

    Catmonkey I Void Warranties! Premium Member Established Member

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    Do you know your cam specs? I've seen them in the past, and I don't know if BPS has changed their grind or not. With a built bottom end and only pushing 15 psi with a near maxed out Gen 1, I'd look at either the 2.65 TVS or the latest 2.9 Whipple. Either one of those should put you around 1,000 on race gas with a pulley change. While the newer versions of the 2.3 would pick up some power, I don't think you'd pick up much more boost and you're one pulley size from the most you'd be able to spin that combination. At 6,000 rpm, that TVS is almost spinning 20,000 rpm with your pulley combination. It's likely generating a lot of heat at that level. You're not going to need that 15% lower with a bigger blower, but if you keep it, consider a larger upper to compensate for it.
     
  8. tvspower

    tvspower Active Member Established Member

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    Builder sent cams for specs n built from there....
    i stayed away from high hp, cause the drivetrain is a PIA...rearend,, clutch, axles, ....etc
     
    Last edited: Aug 7, 2019

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