Horse power limit with exhaust manifold 318

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It's not rpm that matters but hp, a stock 318 grosse under well under 200 hp and even less at 6000 rpm where as a 400 hp 318 (which will be peaking around there) will be moving a lot more air. There's a dyno of 318/360/340/5.9 manifolds on a 300 hp 360 and there's like 5 hp from worst to best even shorties only did a little better. The tube length is what makes headers work. So the more hp you build the more restrictive the manifolds become. If you want say 400 hp you'll probably need to build 440 - 450 hp engine and let your manifolds eat 40-50 hp.
 
Thanks. I understand the concept and I'm not changing the exhaust I have and I know it's a limiting factor.

Is it possible within reason to get into the 13s with my stock manifolds and 2" exhaust is basically my question in a nut shell.
 
Eworth said:
Thanks. I understand the concept and I'm not changing the exhaust I have and I know it's a limiting factor.

Is it possible within reason to get into the 13s with my stock manifolds and 2" exhaust is basically my question in a nut shell.
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Yes
Just got to build a little more engine than you would with headers. Get a cam that's design to work with manifolds and anything else that helps the exhaust side. Pretty sure that's 318willrun's goal and he has manifolds and a pretty mild combo.
 
in 1969,Chebby Econo headers were around $79 Can.And gas was 32Cents a gallonCan.Headers for Mopes were close to $100
'Course I was only making $1.25 an hour.
When you translate that; those Mopar headers cost about 80 hours work.
In 1999 terms when I bought my TTIs at $495; I was making about $22, so that was just 22.5 hours, and that was a top line header.And it was for a Mopar.
In 2016 terms IDK
 
If you are a streeter,
and your budget cannot include headers, I would leave the big cam in the store, and go with 3.55 gears or better.Put some decent seat-pressure on the valves and shift around about 800rpm after your power peak. This might be around 4800 to 5200. You will be fun-quick from zero to 47mph, and just a tad slower to 65, and then you will be speeding anyway. If you need a bit more off-the-line, get a nice 2400TC
Total cost is gears and torqueyTC;Under $1000, for plenty of fun in a lightweight A.
OOps, you will need a SG and or better tires too. Cuz she'll be a ripper, and peg-legging won't cut it......there goes another grand.........
 
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This is PERFECT info. I do have the sure grip 3:55. But not the TC but this is a very good suggestion.

AJ/FormS said:
If you are a streeter,
and your budget cannot include headers, I would leave the big cam in the store, and go with 3.55 gears or better.Put some decent seat-pressure on the valves and shift around about 800rpm after your power peak. This might be around 4800 to 5200. You will be fun-quick from zero to 47mph, and just a tad slower to 65, and then you will be speeding anyway. If you need a bit more off-the-line, get a nice 2400TC
Total cost is gears and torqueyTC;Under $1000, for plenty of fun in a lightweight A.
OOps, you will need a SG and or better tires too. Cuz she'll be a ripper, and peg-legging won't cut it......there goes another grand.........
Click to expand...
 
Well; how do you like it in it's current configuration, and what is the current stall. See; Stock teeners make gobs of torque from idle to about 2400 rpm. So even an 1800TC in a light A will be pretty peppy with 3.55s, up to about 3000 or so.Well 3000 is about 27mph.Of course a 2400TC will put the engine close to it's advertised torque peak, and it will leave that much harder.You won't need much for manifolds to exit that exhaust over that rpm. If you are happy with the current idle to 3000 performance, I say keep the current manifolds and TC.. But if you need more in that range,I would up the TC or pop in more rear gear. Which you choose depends on your hi-way useage.No hi-way use, means gears first. And 3.91s will get you another big fat 10% more torque multiplication. There is nothing you can do to your NA teener engine wise,to punch up the stall-to-3000 torque, that will compare to this increase.
But if you need to keep the Rs down for occasional hi-way use, then the TC would punch up the giddy-up.
A side benefit to more rear gear, is that the engine will wind up quicker to 3000 and to a lower mph. That means it will be putting down more average torque per time period, adding real performance to perceived performance.For instance; 3.91s will get you to 3000rpm at about 24mph.So get ready for the shift! Well not really, cuz with the right spring pressure that teener will pull(with a 4bbl and free-flowing exhaust), well into the 5000s, probably allowing first gear all the way to 40mph and perhaps a lil higher.This sounds like fun to me!
I built one like this, and loved it. It was nothing more than a pure stock short block out of a 73Dart. I added just a small-port TQintake. some valve-springs and seat-pressure and a free-flowing muffler on a single exhaust. Then 3.55s, a SG, 275s and a 2400TC. I dropped it into an 84 D100 no less. It was a lot of fun winding her out.And with the light-weight rear and looong wheelbase,sliding was predictable and super-fun.My son and I have mostly sliding on our brains. We're not into top-end charges.
I guess we're whatchacall posers. Sliding is sooooo much fun.For us 40 to 50mph is the limit, so mostly first gear stuff. With my 367 S- M/T, Second is the good gear
 
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