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Discussion Starter · #1 ·
I'm trying to figure out what convertor i need for my car.
Here's the setup:
3200lb. (w/driver) backhalf car with ladder bars, 5.14 gears, 33x15 M/Ts, 565 BBC w/ 15:1 compression, 289 @.050" intake duration, 1005HP @ 7200 and [email protected] 5700 + single plate system jetted for 150hp, TH400 w/ Pro Brake. I currently have a 10" that I had Coan restall to approx. 5500 stall, but I'm convinced I need a better convertor, because my best 60' is only a 1.32. What do you guys think? Should I go with a 8" or 9"? What stall do you think? Thanks for any input.
 

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Discussion Starter · #3 ·
The 9" converter will be the best for your nitrous application.


Hutch
Thanks Hutch. What stall do you think would work? I'm currently leaving at 5200 on the Brake, The covertor will stall to 5500 approx. and I have the nitrous coming in at 5600 @ 25% and ramping in to 100% (125HP+/-)on the progressive, and the car runs the same 60' as without the spray (1.32-1.33)! Thats probably because its spinning though. According to the dyno sheet from Shafiroff, the motor makes peak torque at 5700-5800, N/A. I'm thinking that a higher stall will get me over the torque peak quicker, but I know a Nitrous convertor needs to be tighter, so...:confused:
 

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Tough to say what it will stall. It has to be configured for nitrous on at 100% to have the right stall speed. It may go only 4500 on the motor and I would suggest a start line 2 step of around 4000. You will likely have to have the progressive ramp in much faster with a dedicated nitrous converter and the car will be a bit of a turd on the motor alone. Although your converter is a 5500 stall now , it likely goes 6500 when the nitrous is on but that depends on how much nitrous you use.


Hutch
 

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Discussion Starter · #5 ·
Thanks Hutch.
 

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Discussion Starter · #8 ·
Ok, I will give them a call.
It has the stock 2.48 first gear.
 

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Discussion Starter · #10 ·
Thanks. I have a 10" now. Since I don't (can't) whack it with a big hit (only 25% initial with a .065n/.057f jet) off the line, I don't see the convertor flashing very high out of the hole. It's hard to tell what my 60' would be, since the last time I ran it the track wasn't prepped much at all (and has a very rough surface) so I was sliding around and could only manage a best of 5.78 w/ a 1.32 60. It trapped at 125mph though and that was on a pass that I was peddling it and had to correct it midtrack (nearly took out the 330reflector, so I know if it hooks good I should be able to get a much better ET. So, I'm thinking maybe i should leave it alone for now, because its hard for me to figure out whether I need to change the convertor until I can get a good run on a prepped surface to see what it does.
 

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i had a 9" converter behind my 555 bbc with 2 stages. it had a th400 with 4.10 gears and 33x10.5w m/t drags in a 3000lb car. it would 1.16 60' and run 5.1x's. would only flash 4700 on motor and 5800-6000 on the first stage. that was a fogger with a 32n jet
 
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