|
Re: 470 to 512
[Re: ProSport]
#1712440
12/26/14 01:50 PM
12/26/14 01:50 PM
|
Joined: Jan 2007
Posts: 305
Mentor,Oh.
fattire
OP
enthusiast
|
OP
enthusiast
Joined: Jan 2007
Posts: 305
Mentor,Oh.
|
Found the card:@1.5 rocker ratio lobe lift-int. 0.435 exh. 0.430 valve lift- int. 653 exh. 645 adv. dur. - int. 289 exh. 300 dur@.050 - int. 259 exh. 267 lobe centerline - int. 108 exh. 116 valve timing int. open 21.5 btdc close 57.5 abdc exh. 69.5 bbdc 17.5 atdc lobe separation 112 degree intake lobe to 108
|
|
|
Re: 470 to 512
[Re: fattire]
#1712445
12/27/14 01:42 AM
12/27/14 01:42 AM
|
Joined: Jan 2003
Posts: 6,591
Canton, Ohio
Sport440
master
|
master
Joined: Jan 2003
Posts: 6,591
Canton, Ohio
|
Quote:
Well it is a street car that goes to the track D.O.T. tires full exhaust air cleaner even a kick butt sound system just think there is some more in it, thinking heads and carb should get me 10.30 - 10.40 
Well, you posted 1.46/1.48 60ft. times. That's kind of soft for the engine combo. More carb and ported heads might even make those 60,fts slower.
But even with that said, those EZ heads OOTB arent that great, so yes have them ported.
It seems you have the budget for the 512, so YES   Id go ahead and do that too. But , I say NO on the 12.5 comp.512 motor, if you do that you've just "lost" your Street car combo. Keep it around 10.5/11.0 max and enjoy pump gas.
Further, that cam you have now will be better suited for the 512 vs the 470.
That 470 is a good motor, if your going to stick with it. Change the cam and port the EZheads and swap carbs. @ 3700# your ride isn't running to bad, but she does have more in her.
With a 1.46/1.48 your running what, about a 10.75 to 10.9 ET If your ET,s are faster then that, your actually running pretty good with that motor at 3700# Maybe you need more Vert.
Id say just go with the 512, more streetable at a 10.5 comp, and plus you know you Want one. 
|
|
|
Re: 470 to 512
[Re: ProSport]
#1712450
12/27/14 04:27 PM
12/27/14 04:27 PM
|
Joined: Jan 2003
Posts: 9,994
Frostbitefalls MN (Rocky&Bullw...
gregsdart
master
|
master
Joined: Jan 2003
Posts: 9,994
Frostbitefalls MN (Rocky&Bullw...
|
David Vizzard's latest book HOW TO BUILD HORSEPOWER has some great info on why and where the LSA should be for different motors. In a nut shell, it is about intake valve to cubic inches,valve to valve relationship, combined with a bit wider LSA for high compression. Our big blocks suffer from small valves to start with. They are also parallel, which doesn't help. Then we stroke them to the limit and reduce the overlap flow needed per cubic inch even more.
When you get into large engines there is a need for more exhaust flow, and in my case with 528 cubes and 7100 rpm shifts it works out to 110 to 112 LSA IF it has more exhaust duration. Because I have over 15/1 compression and poor exhaust flow for the cubes and fuel, it works. The cam timing is brought back to more like a 110 or 108 LSA by advancing it combined with the extra exhaust duration. If you look at the card numbers, my cam current cam which is 284/296/112 installed at 108 looks like a 108 LSA cam with 284 intake and 284 exhaust duration on all three opening and closing points but the exhaust opening point.
With very high compression, the pressure in the cylinder decreases at a high rate compared to low compression, and for that reason opening the exhaust early is less detrimental than the gains from more exhaust flow.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
|
|
|
|
|
