86 la 360 build help
I’ve got a 86 la 360 in my 72 dart wanna do a top end build on it is it worth it to do heads a cam with the stock 8.what ever compression ratio can I get that to a decent number without getting in to the bottom half
For a DD, waste of time.
for a dual purpose with DD rear-gears, waste of time
For tire-fryer, waste of time.
For a track car, well it will be faster.
The point is this; you didn't tell us a single thing about your application other than
72Dart.
Here's the thing; Pressure is heat; heat is power; power is performance and could be economy.
Put a cam in it, with a later-closing intake event, and you are guaranteed to lose pressure. To get the pressure back, is gonna cost you money.
A bigger cam, with no other changes, will move the power to a higher rpm, but subtract power at the lower rpm. The power increase is a sliding window, about 1500 rpm wide. If you are running hiway gears, say 2.94s, and the stock cam that peaks around 4500rpm, that will be ~46 mph.
Getting a decent power increase will cost you about 2cam sizes. That will put your powerpeak at about 5000/51mph with those 2.94s. Will your car be any faster?
Probably not.
why?
Because at under; 5000 less 1500=3500, your engine LOST power. So the average power from zero to 46mph will be close to the same or maybe even less.
In second gear, it might be faster, cuz the rpm does not drop to the factory stall ever again. But Second gear does not start until 51mph and you gotta lift around 65/70 mph. 70 will be 4100... but your power is is just starting! So it's debatable if the car will be any quicker, in Second gear., and probably not at all.
So if you want to be quicker from zero to 70 , IMO, you need a different game plan.
If you want to be quicker from zero to 70;
The very first thing you gotta do is up the stall rpm. And the second thing is to get rid of the hiway gears.
#1
Lets say your current stall is 2000rpm, and your engine make 270 ftlbs down there, which is 103hp
But by 2800, maybe she is making 290ftlbs=155hp... which is plus 52hp! There is nothing you can do to your Normally-Aspirated engine, that can match this change in this range. Which is why it should be your #1 go-to.
#2
Now you need to gear your car to be Reved out at at 70 mph, in Second Gear. so
Say your current combo tops out at 4500, but still makes decent power at 4800. Ok then to hit 70mph at 4800, in Second gear, with 10% slip, will take a road gear of 5.00, and divide by 1.45 Second gear in the trans, is a rear gear of 3.45, rounds to 3.55s. Now this will make your average power from zero to 70mph, about as most as it can be with your current engine.
Will it be faster than the current combo?
You better believe it!
Conclusion;
Go get you some 3.55s, and a 2800, and leave the engine alone; unless of course it burns more oil than gas, lol. If you already have 3.23s, then just get the 2800, because 3.23s will get you 70=4500 @10% slip, ending about right on the power-peak of the stock cam.
Now I realize that this doesn't actually answer your question. But you really didn't give us anything to work with.
Here's my thinking;
If you up-cam your engine, with a later-closing intake valve event, and no other changes; like I said, this is guaranteed to make your bottom end softer. One of the ways around that is to just put a higher stall TC in the trans, and the engine just never has to pull down there. So then, installing a higher stall TC is a given, and that takes care of blasting off.
But the higher-stall does nothing for you after the stall is reached and you are climbing up to the power peak. That will take gears no matter what. So since you pretty much HAVE to do the stall and gears thing, anyway; you might as well spend your money where it will make the biggest change.
Just maybe, stall and gears will satisfy your craving for acceleration.
Happy HotRodding
