At 740ft above sealevel, and aluminum heads, you have the potential to build a screamer. But you are gonna have to co-ordinate very carefully, your Static compression ratio and the cam's Intake Closing Point..... to achieve the end result.
And for a streeter, horsepower usually takes a back seat to driveability.
The 4-speed indicates that you can use a tight LSA cam, and the TBA rear gear is a bit of a stumbling block. I have heard that Oklahoma is large and flat and the cities are spread out,lol. Does that mean you, like me, are miles from nowhere and spend a lot of time on the hiway, getting to somewhere? And what tire-size are you planning to run?
The point is that if you put a 6000 rpm cam in there, you need a matching rear gear, but cruising with 4.30s ain't the most fun thing to do. And 24.5" tires are pretty small, compared to 28s which are about the tallest that will fit in the stock tubs.While the difference in tires is about 14.5%, this is worth between 1 and 2 gear sizes.
So before you chose a cam, you kindof need to nail down the useage; how important is hiway cruising to you?
I like to gear my manual trans combo to be at or near the power-peak at 60 mph at the top of second gear, so I get max performance in two gears, without having to shift into third.
The formula is;
mph= (rpmxTc)/(1056xR1xR2)................. where Tc is Tire circumference, 1056 is a conversion factor, and the Rs are your gears. Rearranging and plugging in the known numbers, we get;
Rpm =(60x1056 x 1.92second gearx R2)/Tc; and I'll use 27" or 85"TC
And that simplifies to; rpm/R2=1431, rearranged to 1431 x R2 =rpm....
And so the power peaks would be
1431x3.23=4620
1431x3.55=5100
1431x3.73=5340
1431x3.91=5600
1431x4.10=5870
1431x4.30=6150
That's what I like to do.
Now here's how this works;
Example #1
Say you put that 284/484 in there and say the power-peak is at 5400. But say you run it on 3.23s; so the rpm at 60mph is 4620. You had to outshift first at about 5700 or 53mph, coming into second at 4110. So your monster 383 has to pull second from 4110 to 4620. Ima thinking it's gonna be struggling, with TM(TorqueMultiplication ) of 6.20.
Example #2
Say you put the same engine together, but run it with 4.30s.So that at 60mph the rpm now would be 6150. sounds good right? But your power peak was at 5400, and the shift point shoulddabin at about 5700. So she is 450rpm past the shift point and already way down on the power curve. You shouldda shifted at 5700/55 mph and third would have struggled again, from 55 to 60mph and from 4150 to 4490, but now with TM of just 6.02. Wait where have we seen that before? Oh yeah, in example #1.
Example #3
Ok so lets put the proper gear on it, of 3.73s
Now you are gonna run first up to 5700@46mph, and shift into second. The incoming rpm will be 4110, and ending at 60=5340. Oh lookitthat we could advance that cam a bit or go to the next gear. And the second gear-TM is now 7.16; whoa! that's 19.4% better than either of the other two; and it began at 46mph, so that monster 383 will be blasting thru there faster than either of the other two combos!
Ok so say you like these numbers, and decide that the 3.73s are what you want. Are you OK with 65=3010rpm?
If yes, then you have to figure out what compression ratio to run with this 284/484 cam,and those 75cc aluminum heads.
And with an ICA of 66*,I get over 11/1. Ima thinking 11.3 actually. And that would take a total chamber volume of 76.28cc. Next question is; how expensive is it gonna be to achieve that.And what's gonna happen if all you can achieve is 85cc? Well 85 would get you just 10.24Scr, and might make just 160psi, and below 3000rpm is gonna feel like maybe a 340. And let's not forget that you can run iron heads at 160,and pump-gas; so you have given up the prime reason for using the aluminum heads, their ability to swallow copious amounts of pressure with out detonating.
But now, if you spent the money to achieve the 11.3Scr, you would be rewarded with so much low-rpm torque, that your car is gonna spin the street-tires all the way to 60mph anyway, and so who cares what gears are back there,lol.
Now go back to the formula, pick a different power-peak
and work it out with a smaller cam, or a cam with an earlier closing intake
