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| Gear Ratio Selection https://www.slantsix.org/forum/viewtopic.php?t=57761 |
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| Author: | MR. DIPLOMAT [ Tue May 26, 2015 8:14 pm ] |
| Post subject: | Gear Ratio Selection |
I am building a V/SA Dodge Diplomat. So, basically a stock 225 with a good blueprint job and a cam with all the duration I want. Looking for a suggestion for a rear gear and torque converter specifics. Thanks |
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| Author: | wjajr [ Wed May 27, 2015 3:55 am ] |
| Post subject: | |
Basically the bigger the cam (increase in overlap) the shorter the rear gear and higher the stall of converter. This marriage of optimal engine torque rpm due to cam choice, converter stall, and rear gear (including tire size) has to be calculated to end up with a combination the works well for vehicle's intended use. Miss the mark with any one of the above parameters and the car won't function as well as anticipated. In other words it becomes an expensive dog. One has to first decide what the car is going to be, a full out race, street & track, daily driver, and design drive train from there. One needs to know cam specs, engine dimensions, compression ratios (Static & dynamic) calculated torque curve, before rear gear, tire diameter, and converter stall is selected. |
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| Author: | nm9stheham [ Wed May 27, 2015 5:26 am ] |
| Post subject: | |
V/SA looks like and SCCA class to me but SA means 'Stock, AWD' so that can't be it! What is V/SA? As above, give more info on what you want to do with the car. Cam and gears will change radically with the application. Is this a 3 speed Mopar trans (904/727)? |
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| Author: | MR. DIPLOMAT [ Wed May 27, 2015 6:35 am ] |
| Post subject: | |
Drag race only. |
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| Author: | wjajr [ Wed May 27, 2015 2:36 pm ] |
| Post subject: | |
[quote]Drag race only.[/quote] So how much money is available to be sucked up in this project, or rather, how crazy do you want to get with this build? Slants are not cheap dates when one wants to make one go real fast. For an example: My car is fully dressed 1967 GT Ragtop, 225cid that was built as a drag queen early 90’s: Head ported, oversized valves, shaved 9.5:1 compression Clifford 4v short intake, Holley 390 cfm, and shorty headers. Cam of unknown manufacture, which will allow engine to turn 6000 rpm & 0.030†over pistons. 904 with performance valve body, 2600 rpm stall converter, deep pan, oil cooler. 8 ¾†Suregrip, 3.55:1 rear gear, 24.5†tall tires. Sub-frame connectors, front K-H disk brake, tubular upper control arms, reinforced lower control arms, 1 1/4†anti-sway bar, stage II firm feel power steering box. Last time I ran her a few years ago on 1/8th mile track: 10.3 seconds, at 68.3 mph. This car was built for quarter mile track. |
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| Author: | DusterIdiot [ Wed May 27, 2015 5:46 pm ] |
| Post subject: | Class Racing |
Quote: So how much money is available to be sucked up in this project, or rather, how crazy do you want to get with this build? Slants are not cheap dates when one wants to make one go real fast.
Regardless he is shooting for a certain class so he has an 'index" per the NHRA handbook that takes factory weight vs. HP into account... V= 15.25 on the 1/4 mile race and SA = Stock Automatic...so he may also be limited on what mods and equipment can be used under the hood pending the NHRA rule book.
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| Author: | sandy in BC [ Wed May 27, 2015 7:43 pm ] |
| Post subject: | |
Mike Jeffries |
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