318 Build
So I've decided to build the top end of my 318. I have a 480 cam, an ldb4 intake, 308 heads, and a holley 750 available. Thoughts and tips? I don't want to build an over fueled dog.
My info on the cam is really shotty. I'll have to get it in my hands to get more and that won't happen for a while. It's just a cruiser but will want to break the tires loss at will. Might take it to a race night or something just to see what happens.
Just had someone measure. 230 @ 050. Didn't measure LSA.
OW!
You're gonna need to;
A) make some compression,or
B) forget about that cam, or
C) start over with a bigger engine, or
D) Start over with a new plan.
The biggest stumbling block is this;
"just a cruiser but will want to break the tires loose at will".
Here is what your cam will do to this combo; I grossed the cam up to 272 advertised and selected a 62* ICA.
Static compression ratio of 8.0:1.
Effective stroke is 2.61 inches.
Your dynamic compression ratio is 6.51:1 .
Your dynamic cranking pressure is 121.91 PSI.
V/P (Volume to Pressure Index) is 92..............................................
92VP
92VP is about as powerful as a 225 slanty.This will never get you the results you want, even if you pump the compression to the moon.
To run that 272cam you need;
Static compression ratio of
10:1.
Effective stroke is 2.61 inches.
Your dynamic compression ratio is
8.09:1
Your dynamic cranking pressure is 162.22 PSI.
V/P (Volume to Pressure Index) is 122...............................................
122VP
This is about the max cylinder pressure that you can run with pumpgas and iron open-chambers..
Now 122VP is not bad, but this puts your powerpeak way up at about 5400rpm which with 2.76s is about 58 MPH at the top of 1st gear. You didn't say you wanted power at 58mph. No you want to lite it up at will.
To that end and interpreting that to mean from a dead stop,mostly, Here is what your combo would look like with the stock cam, and the compression boosted to the max,again;
Static compression ratio of 9.2:1.
Effective stroke is 2.86 inches.
Your dynamic compression ratio is 8.07:1 .
Your dynamic cranking pressure is 161.70 PSI.
V/P (Volume to Pressure Index) is 133..............................................
133VP
Notice the VP is up to 133, which is 133/122=9% more powerful than that 230@050 cam, and a whopping 133/92=
Plus 45% more powerful than the stocker. And the power peak is down at around 4500, or 50 mph with those 2.76s!, which is 8 mph sooner.
.
Now the torque peak of the 272 cam will be at maybe 4000, whereas the T-peak of the 240 cam will be at maybe 3300,700 rpm sooner. There is a slim chance that the 272 will make similar torque at 4000 to the 240 at 3300, but there is a waaaay bigger chance that at all rpms below 3300, the 240 cam will make more torque.
That means below 3300 or 37mph with 2.76s, the smaller cam has a better chance of busting the tires loose, and the slower you drive it the more advantage the smaller cam has.
But this is still a relatively poor way to spend your money!
The cheapest,easiest way to busting the tires loose is with torque multiplication (TM).
So the first thing to do is get rid of that 1750 stock TC (torque convertor), and get you at least a 2800 in there. Next, put the biggest rear gear in there that you can stand. If hiway cruising is not required, then I recommend something in or near the 4s, like 3.91s . These will put your Rs right close to 25mph at peak-torque. So when you go hammer down at 25mph, and it downshifts into first, hang on!
Now, you're gonna need this TC and the gears anyway if you cam it up, so you might as well start here; with the TC and gears.
Now don't go putting 295s on, cuz you know, it's only a teener.lol. But she will break 2.45s loose at will, to about 30mpg,guessing, with a 2800 and 3.91s. And it will all be cuz of the 3.91s cuz the TC will be "locked up" by about 22 mph.
Now, from here,you can put some power into the teener, but without a compression boost you will be trading away low rpm torque for high rpm power, that's just the way it works.
Now in case you're wondering, I used to have a winter engine and a summer engine. The winter one was a stone stock 1973-teener short block with a TQ and headers, that same 2800, and gears; sometimes as high as 4.30s and sometimes as low as 2.73s. My favorites were 3.55s, cuz there was very little tirespin with studded 235/75-14s,(28" tall) then she dug in and got to business,hitting about 40mph at 5000rpm with a 2.74 low-gear. I ran this combo many different ways, the 4.30s were with a stick, and therefore with an adjustable stall,lol, and it smoked 275/50-15s (25tall). shredded them.
I could tell you about the 2.73s and the manual-shift valve-body. This was also a favorite. I would floor that poor sucked out teener and jam it into 3rd as soon as she'd take it without detonating, and then sit back and listen to that TQ moan, and the dual 3" full-length pipes "roar", for what seemed like forever; but was really only maybe 3 minutes to 65mph,lol. Then stop and do it again,lol. What a blast that was. Yeah that was with the 2800,too.So pretty much 2800 from take-off to close to 80 mph,lol!
If hiway cruising is required, then I highly recommend the 2.74 low gear in the trans. This will let you run 3.55s with the same first gear performance as the 2.45 and 3.91s. Ut will be well worth the hunt to get that trans. It will allow you to hit 37mph at about 5000rpm, but the shift into second will kindof spoil things as the Rs drop to 2800ish again. But first gear will be a blast, with a 2.74 x 3.55 =9.73 starter gear. Add the TC TM on the start line, which can be as high as maybe 1.8, so the starter gear could be as high,momentarily as 9.73 x 1.8 = 17.50 to 1. That is tire-frying territory with a teener spinning 2800. This TM rapidly diminishes tho, so don't wet yourself. By the end of the 60 ft it has all evaporated, but the engine Rs are up and into the torque, and you will hardly notice that TC trick.
In your best interest tho, do not install that
[email protected] cam into an 8/1 teener. A 223*fast-rate would be way better for you, and and for torque a fast-rate 216* even better.And if you really wanna burn rubber, pump up the compression. A very nice side-effect of this is the way better fuel-efficiency.
