Good question.
Nick's Garage dyno's a 318 Stroker.
- Thread starter toolmanmike
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My SM heads replaced stone-stock 360 heads that were in good shape.
So, depends on how it's looked at. I could say "not much" because it dropped about 2 solid tenths... maybe 2.5.
- But then I can say my cam is so small it didn't take advantage of the heads. My cam is 204@050 .427 lift.
- I also used the factory stock rocker assembly/pushrods. So, with geometry loss, I can imagine my lift was probably an actual .410 or less.
- At least a half tenth would be attributed to the weight loss, not flow.
Thanks for chiming in. Like they say, There's power in a good set of heads. Wow, that cam is a pretty small one. There's a lot of room to grow there. For another video I bet. That would be a fun one.
If you generalize most street, street/strip type engine builds, cams are in the 215 to 245 range with CR in 8 to 11:1 with appropriate intake/exhaust, Heads in the 175 to 325 cfm range making 1.7-1.9 Hp per cfm and 1.1-1.35 lbs-ft per cid with peak hp in the 4500-6500 rpm range and peak tq 1000-1500 rpms lower.
If you average that out a 230 cam with 9.5:1 cr will make about 1.8 hp per cfm and 1.18 tq per cid give or take.
So 50hp = about 28 cfm
If you average that out a 230 cam with 9.5:1 cr will make about 1.8 hp per cfm and 1.18 tq per cid give or take.
So 50hp = about 28 cfm
It's run 12.8's @ 105 mph with that cam, stock converter, and 3.23 open rear end. We're happy so far.
I’m averaging 290 cfm with a 2.02 valve so it’s easily available if the customer uses the right parts with it. For 100.00 more (2.055 valves) 305-313 cfm is available along with a lot nicer valve job. Ferrea valves are averaging 210.00.
That's a fun place to be. Movin pretty good and minimal parts breakage.
I highlighted the key message: "Minimal parts breakage" - so many look past that until they are complaining about the price of parts.
I do not want to jinx myself, but we got this car on the road in 2016 and the only part we had to replace was the starter. I did that in about 20 minutes with the Doug headers. All other things we have done was just us playing for the fun of it.
But what would you break? While faster guys will be breakin engine parts, you might break stuff like u-joints, engine and trans mounts. Big spender. lol
CUDACOX
Well-Known Member
Hahaha, I love mine!
Dartswinger70
Well-Known Member
I beleive technically this applies to the thread , building a 318 up for horsepower will require machine shop services...people should know what it takes and how long it will take
Depending on the level you want to go. Like any engines, especially when they start life as a 2 barrel, building horsepower doesn't cost much. One or two of these can make a difference in horsepower. Well, performance anyway.I beleive technically this applies to the thread , building a 318 up for horsepower will require machine shop services...people should know what it takes and how long it will take
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Next is an intake and 4 barrel. Too bad dyno time for this kind of thing is so expensive. I bet someone has already done the comparison. Then headers and tune the carb to it. The next step could be a cam unless you wanted to go for better heads and a cam to match. That may include a performance torque converter and/or rear gears to make it work. Depending on where you start, you may be able to add compression with the right heads. Smaller chamber, bigger valve, better flowing ports is a win/win. The last combination would be a stroker. It might not add a ton of horsepower over the head/cam build but it will add more torque and at a lower rpm which is more usable on the street. May be the next level would be turbo or superchargers? Let's not go there though. Not in this thread.Depending on the level you want to go. Like any engines, especially when they start life as a 2 barrel, building horsepower doesn't cost much. One or two of these can make a difference in horsepower. Well, performance anyway.
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Just for as an example with my 70 Teen, I messed with the distributor curve which helped quite a bit. I have a LD4B and a 650 AVS2 that can go on. I also have a pair of Speedmaster aluminum heads that can go on as well. I already have them and they were pretty cheap on the Black Friday Sale. Besides, smaller chambers/higher compression, bigger valves, better ports, lighter weight and aluminum for some detonation resistance ain't all bad. Between all that, I have some 60's 340 exhaust manifolds that I can install at any time instead of headers. I need to replace the exhaust system pretty soon because it is still the original that was converted to duals from way back when. It's pretty rusty. For mild street, the 340 manifolds work well if you don't want to mess with headers and many of the exhaust companies have 340 applications with front pipes that hook right up to the manifolds. If the heads go on of course the cam get's upgraded but there's always the decision how far down the rabbit hole to go. Will I need a converter and rear gear change? Probably so if I go too big with a cam. It's all relative. Just like with any other engine build. Now if I just want to pull the Teen and replace it with a stock 360, there's a horsepower and torque increase there without modifying it with speed parts or modifying the drive train to make it work. Lots of things to think about.
Thinking a 318 needs a stroker kit to make 350-400 hp is a mistake. And in a race to 400 hp, at todays prices, starting from scratch, the 318 is still the better buy on the pocket book than a 340. And 318's have roller cams from about '85 to 2002.
And if looking for 300 hp for a Dairy Queen cruiser, the magnum 318 (sorry folks, it's still a 318 with a 3.31 stroke X 3.91 bore X 8 cylinders) will get you there lock, stock, and barrel for about 500 bucks (that includes buying the engine)
And while I'll say the 360 magnum is the best bang for the buck in the small block mopar world, the 318 magnum is probably the next best choice.
And if looking for 300 hp for a Dairy Queen cruiser, the magnum 318 (sorry folks, it's still a 318 with a 3.31 stroke X 3.91 bore X 8 cylinders) will get you there lock, stock, and barrel for about 500 bucks (that includes buying the engine
)And while I'll say the 360 magnum is the best bang for the buck in the small block mopar world, the 318 magnum is probably the next best choice.
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Dartswinger70
Well-Known Member
I thought they were post J era 360 heads but Im not 100 % on that.
I know where a 318 core is I could get for cheap. Maybe I will, I need something to do after my 340 is together. Can't hurt to have one laying around I suppose. I do have a spare set of j heads to go on it also, you may say I have "one too many sets of heads..."
I know where a 318 core is I could get for cheap. Maybe I will, I need something to do after my 340 is together. Can't hurt to have one laying around I suppose. I do have a spare set of j heads to go on it also, you may say I have "one too many sets of heads..."
Dartswinger70
Well-Known Member
I agree to that. No "seat of the pants" nonsense. LOL! Seat of the pants is cool though I think it would be cool to romp a 318 Duster then get into a 340 Demon, then a 360 Dart sport and make a decision which one you like best ...after driving the same road/highway etc. I beleive it would come down to the earlier car with the non emission drivwetrain etc. but thats just my guess.Whatever you do make sure you dyno it!
Sometimes off the line, the Teen is ahead while the big cube motors are busy in the back spinning their tires. Back in the day cars were rated on how far they could spin their tires. All well and good but they aren't going forward.
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Speaking of which, here's a Dart with a Hellcat. Impressive but fast? Nope. This one will end up wrapped around a tree soon. Here's a link: Video
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