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Why Is This Man Smiling?
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Because he's standing in front of a midget that owes him money??
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Because he just made 758 HP with that thing.
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Because the motor didn't litter the floor.... :)
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Do you have any ideas about the hole (chasim) in your torque curve? Were the Hooker headers or the overall exhaust system too long? The intake runners or the carb spacer too short?
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He just bought a hummer?
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Barry Rabotnick
He had the strongest FE at last year's Jeg's Engine Masters tourney. 505 incher with Blue Thunder heads. Best pull 752 hp.
....Fred |
He know it's a really a 302 'disguised' as a 427... :D
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I wish I had the answer to the crater in the curve. I think they mentioned in this months Popular Hot Rodding article that we ran into a "twilight zone" quality issue on the dyno. The engine ran smooth and solid all the way to 6500 - - and it was a pooch - - down by 100 from expectations. Though we eventually found the problem (a coil) it killed us a full day for tuning time.
I can tell you that the hole is entirely insensitive to timing and fuel changes - - we had the A/F all over the map, and ended up with a very smooth 12.5:1 as a reference for the contest itself. We also tried a variety of carb spacers that only seemed to push it around a bit. With more time we'd have tried a different cam. We also would have tried some header options - - seems the rules guys were flexible - - with others using smaller or venturi collectors (I saw a bunch of 3" stuff on applications where I know they would ship with 3.5 like I had). Next year's contest is 434" so I expect that the package will change a bunch... |
Have you played with Larry Meaux's PipeMax? The intake ports are clean, however I'm wondering on the lengths.
Is there a way to get longer intake manifold runners? |
Its an FE. The runners are already as long as your leg... JK :)
Realistically, the modified Victor seems much better than a tweaked Dove I also have. Of course my old Holley Street Dominator (complete with about three pounds of epoxy) was also better than the Dove, but external welding rendered it illegal. The cam on the other "sister" engine is longer duration - - has the same RPM HP peak, and it soots the intake so I know thats not right. I have the HP peaks right where I want them at 6300-6400. I just have a "feelin' that some exhaust changes - - maybe dropping pipe dia or collector dia - - would help fill the hole... A shorter cam might find its way in next time... |
With the lower compression this year, I wondering if the intake duration may end up with an LS7-like 20° difference between intake and exhaust. Are you also looking at lobes with more lobe lift, .45-47"?
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That may be it. I tried a comparison and this is the result:
http://www.clubcobra.com/photopost/d...Comparison.jpg The one with the hole at 33", 2.125 (2" ID) primaries, the one without had 29", 1.875" (1.75" ID) primaries. |
Boy that looks familiar.
The rules call for unmodified production headers for a passenger car. I literally ran the ones from my car - 6876 Hookers, along with also trying a set of 2-1/8 dyno pipes for reference. The bigger ones killed the whole lower end so I knew which way to go - but never had the chance to try smaller yet. I wanted to run some Cobra headers - - hey they were factory in '65 right? Rule guy said that they would not like that. Next bet looks like some 6113 Hookers.... |
Also note, that although the peaks, at 4750 and 5750, are lower than you had last year. When I try to optomize area under the curve from 2500 to 6500, it seems to prefer setting with peaks around there, and that flat-in-the-middle torque curve. For that curve I was using a TK Hi Lift Roller, .470 @ the tappet, over .800 at the valve; 252/276 107.5+1.5
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Yeah - - that peak at 5750 ain't gonna cut it - - it drops off way too fast looking at the curve. I'm suspecting that we'll end up with a non-conventional cam to get what we need. I would expect to investigate the header thing though.
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Well, I can't match your experience. However (I love those howevers), this contest is over 61% of the engine speed range, vs. 25-40% for a typical race engine. Peaking 5% from the top at the expense of the bottom 20 percent may be to much of a trade-off. I'm surprised that the torque peaks on my analysis are at 4750. I was expecting closer to 4000, more like a Viper.
The rules also added torque and power. In a race engine, I'm only looking for power...the gearing handles turning it to 'torque'. Here, they add both. So, those low engine speeds are more important then they should be. 5 lbf-ft at 2500 is only 2.5hp, vs 6 hp at 6300. 2.5x the power. But since the torque counts that is 7.5 vs 8.5. Only 13% more. And since the engine would be losing ti over 2000 rpm, vs gaining it over 1000...it isn't as clear. BTW, are you going to get 434 the extreme way: 4.44 x 3.5? |
Finances dictate a conservative approach this year - - as always. That means 4.350 x 3.64. I have a crank in the works right now.
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That's what makes your results so amazing...some of the top entries are so extreme...
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Why is he smiling???
Barry why are you smiling? we can only see you from the chestup;) That cheesy smirt is what worries me, was there a blue bottle in that oil pan?? Nice write up in HR, sure they could have put it a couple more pages to the rear like in the 120's? Is where a groove in the lifter rollers on page 105? Barry is it possible that the dip in the dyno pull is from the load of the dyno?Boy you run lean 13.3? I know you are working on the 434, are you going with the same heads? Why this big bore thing when the winner ran a long stroker and small bore. Cam was huge. @ of the others also did well with small bores. I know about the 1.88 honda rods and bearings and low resistant drag on internal parts. The gas porting for the rings makes some good sense. Do you know what the dip was at 5950 rpm? Did you run a PVC valve on the motor? Could the drops be a timing curve change in the MSD? I would like to see what a set of 26095 springs would do on the same motor. As for that I built it in my GARAGE thing, Warren Johnson, Bob Glidden, and a host of others build motors in there garages. Gollllllly. Great Job, even Jon Kaase is looking over his shoulder%/ DavidNJ are you in Jersey and what Part?? Rick Lake
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