How Much Can Heads Improve Compression???
Now I hear Rumblefish blathering on about How I am stupid for not shifting at the power peak or a little after.
Enclosed please find a dyno curve similar to mine.
So let's say I do it
Rumble's way and shift at 5900, which I imagine will be 430hp. Now imagine I have a TF and the 1-2 split is 59%, so the Rs drop to .59x5900=3480.... and there we have 250 hp. So the simple average power put down will be; (430+437+250)/3=372
Now my way, I'm gonna run it up to 6400@414hp, drop to .59x6400=3776, and now I have 275 hp there. So the simple average is (415+437+275)/3=376; So I lost 15hp after the power peak, but I gained 25 at the bottom. That's like a full cam size down there, maybe more.
But wait, my way is better for another reason; look at the shape of the torque curve. Look at the pivot point at about 3900. From that point and lower, the torque falls off faster, so I want to be above 3900 to take advantage of the meatier curve, and build a higher average power.
But I don't have a TF, I have a manual trans with splits of .78-.80-.78.. So if I shift the 1-2 at 6300@412hp, and drop to .78x6300=4914, where the power is 400hp, my simple average will be (412+437+400)/3=416. Yikes! This is nearly11% more than the 376 and nearly 12% better than the Rumble-Way
And if I shift the 2-3 at 6100@430hp, dropping to 4880@410hp, With the .80split my simple average will be (430+437+410)/3=426......
That shift happens a 72mph, and I am heading to [email protected] the wind at full-power. I think this is why my little 367 goes 93 in the 1/8; it's up on the cam, almost the whole way. You can see it is putting power down, like it had a cam more than 2 sizes bigger. Thank you GearVendor.
But I could just as easy go to 6300@412hp, and drop in at 5040@420hp, for a simple average of (412+437+420)/3=423.......
Your results may vary,lol.
To be fair
I agree that if your powercurve drops like a stone after the peak, then you would do yourself a dis-service to spend more time there than you need to. I always talk streeters, that's all I know. With a TF you gotta carry the revs, or go to the basement, so if you put a combo together that doesn't carry the power but falls like a stone after the peak, well, dig out the sundial.
As for me and my stock-cammed 318,I'm holding her in second "til she hits 60 or blows up.
I'm a lil like Willrun, I screw my junk together and watch it run. Bolt on an 850TQ, on a small-port intake, on an otherwise stock lo-C 318, with TTIs and twin full-length 3" pipes, ,a 2800TC,with 4.10/4.30s, and watch her fly! Find something to hang onto passenger.......
Chart pirated from Hughes Engines
Now I hear Rumblefish blathering on about How I am stupid for not shifting at the power peak or a little after.
Enclosed please find a dyno curve similar to mine.
So let's say I do it
Rumble's way and shift at 5900, which I imagine will be 430hp. Now imagine I have a TF and the 1-2 split is 59%, so the Rs drop to .59x5900=3480.... and there we have 250 hp. So the simple average power put down will be; (430+437+250)/3=372
Now my way, I'm gonna run it up to 6400@414hp, drop to .59x6400=3776, and now I have 275 hp there. So the simple average is (415+437+275)/3=376; So I lost 15hp after the power peak, but I gained 25 at the bottom. That's like a full cam size down there, maybe more.
But wait, my way is better for another reason; look at the shape of the torque curve. Look at the pivot point at about 3900. From that point and lower, the torque falls off faster, so I want to be above 3900 to take advantage of the meatier curve, and build a higher average power.
But I don't have a TF, I have a manual trans with splits of .78-.80-.78.. So if I shift the 1-2 at 6300@412hp, and drop to .78x6300=4914, where the power is 400hp, my simple average will be (412+437+400)/3=416. Yikes! This is nearly11% more than the 376 and nearly 12% better than the Rumble-Way
And if I shift the 2-3 at 6100@430hp, dropping to 4880@410hp, With the .80split my simple average will be (430+437+410)/3=426......
That shift happens a 72mph, and I am heading to [email protected] the wind at full-power. I think this is why my little 367 goes 93 in the 1/8; it's up on the cam, almost the whole way. You can see it is putting power down, like it had a cam more than 2 sizes bigger. Thank you GearVendor.
But I could just as easy go to 6300@412hp, and drop in at 5040@420hp, for a simple average of (412+437+420)/3=423.......
Your results may vary,lol.
To be fair
I agree that if your powercurve drops like a stone after the peak, then you would do yourself a dis-service to spend more time there than you need to. I always talk streeters, that's all I know. With a TF you gotta carry the revs, or go to the basement, so if you put a combo together that doesn't carry the power but falls like a stone after the peak, well, dig out the sundial.
As for me and my stock-cammed 318,I'm holding her in second "til she hits 60 or blows up.
I'm a lil like Willrun, I screw my junk together and watch it run. Bolt on an 850TQ, on a small-port intake, on an otherwise stock lo-C 318, with TTIs and twin full-length 3" pipes, ,a 2800TC,with 4.10/4.30s, and watch her fly! Find something to hang onto passenger.......
Chart pirated from Hughes Engines
