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Highest Naturally Aspirated Torque? BBC

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Old 10-09-2008 | 08:55 AM
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Originally Posted by Noise Pollution
I kinda did the same as t500 hps . 502 mpi converted over to a 540 with a carb. 630hp @5300rpm. 700 lbs tq. Crain 741 cam. Dart Iron Eagle heads with some port work.
My numbers were with dyno headers, no accessories.

Sounds like a strong long life motor!!!!
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Old 10-09-2008 | 08:24 PM
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Originally Posted by SB
Not always.

Many builds that concentrate on torque from low to midrange power trip over themselves trying to get a good high speed #. On the reverse, many builds that concentrate on too high of an rpm power peak, trip over themselves in the low to midrange power.

Depends on what exactly you are trying to pinpoint here.

Can you tell us more exacts of what you are thinking and what you are trying to achieve and with what ?
I am in the process of building a new 598" motor and looking for some good ideas to make the most of each cubic inch but not by twisting the thing to the sky RPM wise. I am interested in what can be achieved in big torque because I think that it allows more upper midrange efficiency in the fact that you can turn a bigger pitch prop with a given gear ratio. What torque does a Hawk 750 572" motor make and at what RPM? for example.
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Old 10-10-2008 | 07:56 AM
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If you were to build a 598 with small port but high flowing heads like AFR 315 cnc and a small cam like a 741, you'd probably end up with about 700hp and 775lbs of torque with out revving high.
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Old 10-10-2008 | 08:03 PM
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Remember that big ci usually delivers big torque (650-700+ lbs) from 3000-4500 RPM. This torque is what breaks Bravo drives. If you hold ci to the 500 ci range, you can hold the torque to 550-650 lbs and still make 600 HP at 5250...650 HP @ 5500 RPM and 750HP at 6000 RPM....all with under 650 lbs torque. We have a lot of boating hours from 3500-6000 RPM and have never broken an XR style Bravo drive. We also see zero gear wear on the magnets.
If you up add up the total cost of mantaining the drive train you may find the 540+ ci may not be low life cycle cost for the entire drive train.
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Old 10-10-2008 | 08:25 PM
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So if you have a clean sheat what do you build for a modertly preforming 40 v bottom say 70 to 80 mph range . All the torque you can ? Or cut back on trq. and build some hp.Also keep in mind some type of longjevity probibly not allot of rpm. Im runnig TRS and Borg W. trans.
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Old 10-11-2008 | 08:47 AM
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Start with a pair of Konrads. Any amount of hp is going to cause expensive drive problems. Last year I broke an upper, this winter I have to rebuild a lower.
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Old 10-11-2008 | 09:11 AM
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Originally Posted by IRONMAN
Who has some really high N/A torque numbers from a Big Block and with what combo to make it? HP is no object Torque is king for this post.....

Here ya go...get you a peek at this dyno printout sheet on a motor I did last Easter. Notice the HP and torque at 5300 rpm. This was done on a single Holley carb. This pic is the motor that made the power.

Last edited by pslonaker; 07-24-2012 at 11:53 AM.
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Old 10-11-2008 | 11:04 AM
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My 540s reach max torque at 5000 rpm. We went after hp since I wanted to keep the Bravo drives.
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