340 Build help please.
I'd be more concerned with building more ave tq per cid than peak hp numbers, an average build range 1.15-1.25:1 tq:cid, which 1.25 + is a big difference over 1.15 -, 431tq vs 396tq, plus lowers were peak occurs for a given hp by hundreds of rpm probably 500+ rpm.
To that I add that, for a streeter, torque off the line can easily exceed the tire/chassis ability to deal with it. In fact, it may be 40/50/60 mph before the chassis catches up.
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I know for a fact that my chassis cannot handle it. By it's trapspeed, my current combo 367 is making ~430 hp with a 230*@.008 cam... and the peak is around 5250, so as we all know, at 5250, torque equals horsepower. But at the torque-peak, it will be more, using @273s 95% estimate, that makes it about 450 ftlbs; somewhere near 3800, which, in Second gear for me, is 44mph. Hammer-down at 44mph results in instant tirespin with 295/50-15s.
The point is, what streeter needs 450 ftlbs?
I have a rule of thumb,
It goes like this;
If all you can fit on your car is 255s, then 255 crank hp is your target.
If you can install 325s, then 325hp should be your target.
Anything more, on the street, at WOT, is all of it going to tirespin, and bragging rights.
A stock rebuild lo-compression 360 with a 4bbl and headers, is already around 255 hp. Throw in a 220* cam and its pushing 275hp. Pop the compression up, and yur knocking on 300, a lil headwork gets you to 325, another couple of cam sizes is near 360
If yur replacing pistons anyway, it costs the same to rebuild from 255 to 300 maybe even 330, but headwork is where the money goes. So I get it, throw a 292(
[email protected]) cam into it and have at it.
But the 292 cam will not be happy with the stock convertor nor 3.23s, so right away yur looking at gears and a TC, and an 8.75 rear end if you don't already have one. mo-money,
and I well-remember, that the 292 cam was not all that much fun for me. even with a clutch; plus it drank fuel like a two-hump camel on fire. mo-money. It was only in there for one summer,
If I was to do it over, with a 360, I would top out at ~330 hp, which if an HFT, then a 218* cam, and 3.23s; the clutch is staying.
But if a 340, I'd want a lil more low-rpm torque with that clutch, so I'll trade some advertised duration away and get a Solid lifter cam.
A hot streeter, does not mean a detuned race car. Build your car for it's intended purpose and whatever you get at the track .... is what you get.
My 360 combo has run three cams;
292/292/108 which was 250/
[email protected]
270/276/110 which was 223/
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276/286/110 which was 230/
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Guess which combo was the favorite... HYUP the lil 223* was; All the torque I could ask for, fuel-thrifty, and still went 106 @12.9. I drove that thing everywhere all the time.
and yes; Major tirespin at WOT.
By it's trapspeed of 106, the Wallace pegs it at ~335hp. Super-fun car.