1967 Barracuda 383 tuning tips
I just read an old Hot Rod article of them going from the stock 330 hp 383 B engine to 454.9 hp at 6,000 rpm, and 456.6 lb-ft of torque at 4,800 rpm with just a carb, intake, headers and cam swap. That means running that power on stock heads. Could this really be true?
For a Streeter, the problems with a power peak at 6000 are twofold;
1) what gears are you gonna HAVE to run?
2) what Stall you are gonna HAVE to run?
6000 with typical 3.23 gears and 28s is 60mph, so you have a one gear to 60 combo. With 3.55s yur gonna hit ~6600, and that usually calls for a shift. Anything after 3.55s WILL require a shift, and that's when the nose drops and yur done.
So right away you sorta limit yourself to 3.23s or 3.55s.
But worse is that the cam to powerpeak at 6000 is probably a fgriggen huge unstreetable beast.
But worse than that is, The powerband of most cams is rarely wider than 1500 to 1800 rpm. So when you peak at 6000, you might carry that to 6400 and on the shift, the Rs drop to 59%, so ~3800, for a drop of 2600, well outside the powerband of that cam.
But even worse is what happens to the bottom end, off-the line jump. It just goes away; Crimminy a 5.2Magnum will blow it away; both with same stall TCs.
But even worse is what happens to the cylinder pressure. With iron heads you run into a wall at about 165psi and pumpgas. and with a cam as big as is required for a 6000 rpm power peak, finding 165psi is gonna be tuff, and if you can't make it, yur bottom-end goes away, or you need a higher stall TC to get off the line.
So yes; maybe you can make 454.9hp, but it comes at an rpm that you don't normally drive, and at a huge cost to street performance.
Where do you spend most of your time? would it be idle to 40 mph? I'm guessing yes. So, what gears do you want to run? Most of us streeters top out with 3.55s so we can hit the hiway at 65=2770(zeroslip) with 28s.. That means 40 mph in first gear is ~4400 at WOT. Well then,you want the bulk of your power from stall to 4400. Make sense? What good is 455 hp at 6000/55mph if you only go there for say 1 minute a week, compared to say 15 hours a week at below 40 mph; or whatever; you get the idea.
There is no Mopar streetable combination of 727 transmission and rear gears that will get you 6000@40 mph. It does not exist. The closest you can get is 4.88s, which is not streetable at all.And you still have not addressed the complete lack of traction with 4.88s.
On the street, if you can't make it hook, more than 350/380ish hp is kindof a waste. I mean, you might ET a hair quicker in the zero to 60mph contest, but firstly, it won't be by much, and secondly, IMO, the sacrifices made to stay with the short stroke, are just not worth it. and thirdly; what your engine lacks in power, you can usually make up for with gearing.
The combo I earlier outlined, is based loosely on my 367 which is a terror at 93mph in the Eighth. But it already is on the limit for an HFTcam (IMO) cuz I just cannot get good fuel economy out of the early-opening exhaust valve. My next cam, if there ever is one, is for sure gonna be a fast ramp solid-lifter design, and I'm gonna push the pressure closer to 190, and I'm gonna tighten up the LSA some more..
According to my 1/8th trapspeed, at my weight and elevation, my 367 is putting out 433 hp.
But IMO, that is not correct. The Wallace calculator does not know that I have a GVod that I use as a splitter. When I ran that trap I was using four ratios;
first, 1-od, second,and 2-od ; and the splits are .78-.80-.78. So my engine never falls into the hole that the 727 makes with a 1-2 split of 59%. It's kindof like running a CVT, the engine is always very close to peak-power. The Wallace has no way of knowing that, so it just spits a number out that it thinks it outta be, based on it's programming.
I don't know how much power my 367 is making, and frankly, I don't care... Because it is such a pleasure to drive as it is. It has the right amount of power, no matter what I'm doing, because it always has the right gearing.
I'm rambling now so
over and out
