13 seconds might be pushing the reliability factor a little. Shoot for low 15's. There are lots of builds on here
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| Suggestions on how to build my slant six https://slantsix.org/forum/viewtopic.php?t=38575 |
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| Author: | /6 Matt [ Sat Jan 09, 2010 9:09 pm ] |
| Post subject: | Suggestions on how to build my slant six |
After getting many much appreciated replies on my previous topic "Exhaust, Carb, Cam, head, and rear end questions" I became aware that I trying to use the "cookbook method"... So my question is, how can I use a 225 slant six and a A833 overdrive transmission to move a 1970 Dodge Dart through the traps at 13 seconds while maintaining at least 16 mpg along with a stock weight? Or is that senario impossible? I intend to use the car primarily for thrilling cruises and tire shredding. Looking into disc brake conversions and I intend to rebuild the suspension with polygraphite bushings, sway bars and big block torsion bars (for 383 restos). |
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| Author: | Jester [ Sat Jan 09, 2010 10:35 pm ] |
| Post subject: | |
13 seconds might be pushing the reliability factor a little. Shoot for low 15's. There are lots of builds on here
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| Author: | Joshie225 [ Sat Jan 09, 2010 11:11 pm ] |
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13s are a lot to ask normally aspirated and stock weight. I'm shooting for 14s and will spray into the low 13s or high 12s. This build includes a ported head with 1.70"/1.44" valves, +.040" stock replacement pistons, enough off the block and head to get 10.2:1 compression and a 268° advertised, 230° @ .050" tappet rise .483" lift cam. The 3-speed manual comes out for a built A904 and high stall 9.5" torque converter. If you really want 13s with that trans I would go super mild on the cam and turbo the thing or maybe a positive displacement supercharger to get a lot of low end torque. The A833OD has the same problem as a 3-speed and that is the RPM drop between gears. The faster you spin the engine the greater the RPM drop. With a mild cam you don't spin the engine as fast and the gear spread isn't as detrimental to performance. Big cam duration, high RPM engines need a lot of gears. I've played with enough combinations and lost enough off-idle torque (and it doesn't take much!) to really show the problems/limits of stock torque converters and too little rear end torque multiplication. BTW, It costs just as much or more for a good clutch and flywheel as it does for a good toque converter. I did the math on going from a 3-speed to a built automatic or a 4-speed and they were within $100 of each other. Your car being an auto would make the manual option more expensive unless you're getting the clutch pedal and linkage for free. For brakes I like the '73 and newer factory stuff and the much more common 4.5" bolt pattern. If you aren't happy with the stock 10.87" rotors you can change the caliper stands and use 11.75" rotors. I'm not a fan of poly bushings on the street. Nor am I a fan of a lot of positive caster. I do like big torsion bars and good shocks. My 3000lb Valiant has 1.04" torsion bars and QA1 shocks and it rides much better than my friend's '94 Corvette convertible! I may drop down to .990" torsion bars since I have a set in my V8 Dart and the Dart would get the 1.04" bars. There are no good high performance 15" street tires available for cars our size any more so I have 17" wheels. There is a short video of my Valiant on my friend's little dirt track on Youtube. About 1 and a half hot laps. BTW, no sway bars on the Valiant just yet! http://www.youtube.com/watch?v=g4fv0N3LvAw |
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| Author: | ceej [ Sun Jan 10, 2010 5:55 am ] |
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I take it you haven't clicked on the Frequently Asked Questions link above? There's a great deal of information there including an Engine Build Matrix. The Tech Articles I provided a link to also have some build information. Is this car a manual already, or does it have an automatic? You'll give up a tremendous advantage at the tree swapping a manual in there unless you're very, very good. CJ |
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| Author: | runvs_826 [ Sun Jan 10, 2010 1:52 pm ] |
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Frankly I don't think 13's is a realistic goal at all, 15's is a lot closer. In all fairness that is as fast as the new hemi's are stock and many other v8's back than. In fact a certain Barracuda on this went to a 318 and went slower to the 15's. Alot of the same engine building stuff applies here, I would stick with the cookbook stuff especially for your first slant build. |
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| Author: | Reed [ Sun Jan 10, 2010 3:28 pm ] |
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I think the best first step you can make is to determine what RPM range your motor will be operated in most often and then build to make the most power in that RPM range. Don't over cam, don't overcarburate, do come close to overcompressing. |
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| Author: | Dart270 [ Mon Jan 11, 2010 6:29 am ] |
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In my book, the first steps are: 1) Decide on a total budget for drivetrain. 2) Decide what kind of fuel you want to run. 3) Get a car weight and estimate what your final weight will be. 4) Make realistic goals for fuel mileage and performance level you want. After that, we can start to talk about rational drivetrain plans. Lou |
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