Big chamber vs small chamber

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by Danny Humphreys, Dec 1, 2004.

  1. Danny Humphreys

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    I have a question for all you hemi experts. What is the difference between a big combustion chamber motor, ie Veney, AJ/WAR and small chamber Brad 5 combo? I realize a big chamber combo takes a heavier piston to get the compression where it needs to be, but is there a difference in power, is one more forgiving than another as far as tune up, easier on parts, etc? In this scenario lets assume that overdrive is not limited, and running a screw blower so boost is not a problem either, so it would not be necessary to spin the motor past 8500-9000 rpm. Any thoughts?
     
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  2. rpmhiperf

    rpmhiperf Blown Alcohol

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    The Brad 5&6 stuff makes more power because the ports are better, The smaller chamber makes a lighter recipicating assembly so you can spin it harder and not kill the bearings as bad. :cool:
     
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  3. Mike Pavia

    Mike Pavia Member

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    Who says the ports are better?
     
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  4. rpmhiperf

    rpmhiperf Blown Alcohol

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    You're right, I don't know about the WAR/AJ combo/heads. Only that the Brad 3's are also big chamber and not as good as 5's or 6's. And require the heavier piston as well.
     
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  5. Dragster503

    Dragster503 Dragster

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    There has got to be something out there since Veney's and Brad's (5/6) are at opposite ends of the scale (valve and pocket size wise), but both are part of winning combos. We have WAR stuff as well and they fall somewhere between those two.

    Surely there is a way to run Veney sized valves with a Brad 5 type piston weight (600-650g)....
    .....
     
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  6. Mike Pavia

    Mike Pavia Member

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    What bore size is the 600-650 gram piston. Our 4.310 piston weighs 775 grams.I would just like to know for my own information. Thanks Mike
     
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  7. Dragster503

    Dragster503 Dragster

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    Not sure on the Brad 5 stuff as we are running WAR parts for now. Our 4.310 piston is 740g with the rings. I'm also curious how the total flow heads compare.
     
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  8. Maynard

    Maynard none

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    Gene, I have a set of billet Veneys with 160cc chambers I want to try. Are you recommending 50-55 degrees lead on those as a starting point also?
    EDIT: Single Mag without alot of boost. Just trying to make 1500-1800 hp.

    [ December 03, 2004, 01:53 AM: Message edited by: Maynard ]
     
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  9. john348

    john348 Top Alcohol

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    on what fuel, NITRO???
     
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  10. Mike Pavia

    Mike Pavia Member

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    If you put 50-55 degrees in with any head on alcohol, It won't make it off the jackstands.I had a customer accidentally put 40 degrees in, and blackened 4 mains, and 3 rod bearings.
     
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  11. Tad117

    Tad117 Member

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    Hey Mike how is the weather up there? Did you sell your sled? franny
     
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  12. Mike Pavia

    Mike Pavia Member

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    Hey franny, Sold it, and another will be here within the week.
     
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  13. dirty rat

    dirty rat Jr. Dragster

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    Mike" as a point of referance for myself and many others, what timing do you recommend for a large chamber engine? Is there a differance between a 450 vs. 526 cuin., roots vs. screw, single mag. vs. dual and dragster vs. funny car. Thanks STAN
     
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  14. Tad117

    Tad117 Member

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    Mike how is the weather looking any snow on the ground yet? So what did you 600 1000
     
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  15. Mike Pavia

    Mike Pavia Member

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    Stan, There are many different ways to run each combination. if you want to talk about a particular combo, send me an e mail, or call me 518 864 5575. monday-friday 8:30-4:30
     
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  16. Mike Pavia

    Mike Pavia Member

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    We got 2inches last night, but it is already melted. another 440 racer. But i will order another new 600 in the spring
     
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  17. FAT HEAD JOE

    FAT HEAD JOE racer

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    correct me if I'm wrong if you run 27 on the lead with brad stage 5 heads your crank will live longer like 40 runs Vs big chamber heads with 40 to 48 on the lead 25 runs or less on the crank . joe
     
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  18. Mike Pavia

    Mike Pavia Member

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    Who has big chamber heads and runs more than 32 degrees with an MSD 44?
     
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  19. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    28-30 degrees on fat head :eek: maybe in a low compression application. i wouldnt think you could get away with anything over 10:1 cr with that on an entire run.
     
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  20. BenchRacer

    BenchRacer Super Comp

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    OK I’ll take a crack at it, the taller piston dome might limit the flame travel. That is why Fathead stuff can run leaner or on less fuel volume, but the bigger chambered Hemi heads flow better, because of valve size, angle ??? The Fathead takes less timing because it needs less flame travel, but I think most combos even with the bigger chambered heads are in the low to mid 20s on the timing with a single MSD 44. Although some combos have certain mechanical advantages and disadvantages over the others as long as you have the latest stuff none are easier on parts in all areas. The biggest thing that makes them harder or easier on parts is the kind of tune up some run them with a lot of compression and fuel, but if you are off a little, the blower will be sitting in your lap. On the other side you can run low compression and a lot less fuel and it will haul ass as it melts its way down the track if the wick is long enough.
     
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