MSD Hemi-6 and accompanying harness. Not super expensive, not junkyard cheap, either.
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Thoughts on a 390 cu in. stroker from a 318?
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Rug_Trucker
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Anyone remember HotRodDave40 on Moparts? He was a local friend here until he moved to Montana. He built a 318, actually 2 of them. First one he bored it out further than the casting would allow he crack a couple of cylinder walls. He didn't have all the cylinders checked. It was a weird combo. 273 2bbl cam. Magnum heads, Edelbrock LD340 850TQ 10:1+ compression straight headers with exhaust running out to the rear on his '69 Barracuda coupe. He built it to run E85. Got 29.5mpg on the highway and would spank 5.0 mustangs hard. I'm trying to remember if he had a stroker crank in it. IIRC he was in the lower 400's for displacement.
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i built one for my buddies a-100. A little scallop in the bottom of cyl was all the clearance needed for the rot assy. Kept a small cam in it, due to most of the driving within city limits
I am used to reading threads where the guys build strokers for big power. In some applications, that just isn't necessary.
Problem with gaining low rpm power is the percentage of power made from torque at lower rpms, e.g.. 25% at 1,313 rpm, 50% at 2,626 rpm, 75% at 3,939 rpm, 100% at 5,252 rpm etc.. Every rpm has it's own percentage, as rpm goes up percentage gets higher and more importantly for your application vise versa. Which means big torque gains only make small to moderate power gains at low rpms, why diesel are preferred for low rpm power cause of there ability to make huge low rpm torque per Cid.
Or long stroke gas engines. (take old tractor engines for example) All torque, little horsepower, low compression and low operating rpm.
Woody500
Well-Known Member
318s were used as Marine engines because boat engines require, wait for it, torque. It's what moves a boat, not horsepower.
Let the arguments continue.
Let the arguments continue.
When you say power you mean horsepower right? Not sure what point you're making with this comparison. If comparing a similar built smaller cubic engine at the rpm range where the op wants his power won't the smaller cubic inch engine have less horsepower in that same rpm range? The formula for hp is torque xrpm÷ 5252. So if the rpm is the same and torque is more Hp is going to be more. I don't see what difference the percentage makes as you can't change it. It's built into the formula. Or am I misunderstanding what point you are making.
Outdrive and prop have a major role in getting a boat out of the hole.
Yes
Yes, but by how much for the extra dollars spent making a 390/408
Cause gaining eg. 30-50 lbs-ft @ 1,313 rpms = 7.5-12.5 hp and double that by 2,626 rpms the questions is it worth it to the OP especially 365 VS 390 (least gain), maybe, if the 365 is definitely gonna struggle more power will obviously help but if the 365 will be fine at towing, then extra is really not needed.
360's are only good for flatland towing, I would never handicap myself by using a 360 to tow anything bigger than a riding mower. lol
But bet you wouldn't just only step it up 25 Cid (390) and go straight for a 440
If the 365 has enough then that would be the most cost effective. If cost per gain is the metric then the 390 makes least sense. If the 365 isn't enough where are you going to get more torque/ HP in the rpm range that the op is looking at for less cost per TQ/ HP than what the stroker 360 will provide?
Agree, the choice to me is 365 VS 408, if money isn't really a concern then 408 is probably the best move. But if wants to save a few bucks, OP might just have to down shift a little more often and live with the 360. 390 don't make much sense to me for the
OP's stated goals.
I know what I'm talking about when it comes to towing, stroke gets the work done at a much lower rpm. add cubes and it's even lessBut bet you wouldn't just only step it up 25 Cid (390) and go straight for a 440
Woody500
Well-Known Member
Outdrive? We don't need no stinkin' outdrive!
Inboards rule, dude.
Outdrives are just another scam foisted on the public with promises of superiority, and less initial costs & ease of maintenence. All bs of course, as profit and convincing the public was all they cared about.
I have seen on the dyno motors with a good combination of parts and a bad tune that were under performers. I've also seen less than optimal combinations that, no matter how you tune them, they don't run that well. I've also seen motors that ran well on the dyno but ran poorly in the vehicle due to wrong engine combination for the application, gears, tire size, converter or ????. It is possible that the 408 is running great and your expectations are too high due to what you have heard others report or "over report" about their 408's. Without measuring the performance of your son's 408 it might be hard to tell if it is a case one of these scenarios or a combination of them that is the reason for your less than impressive performance.
Whatever you decide to do, try to focus the entire combination/tune towards working together for your goal. Good luck, I hope in the end you have what you were shooting for.
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100% what 92b said, it’s all in the combo, but also under 2500 or so rpm’s it’s mainly displacement but like I pointed out it’s hard to make substantial hp (work over time) gains, it would take 800 lbs-ft to only make 200 hp (not a crazy amount of power) at 1,313 rpm’s by 2,626 rpm’s a little easier only needs 400 lbs-ft to do so. But luckily you don’t need a crazy amounts of power to drive and tow.
Woody500
Well-Known Member
Notsure what you're asking, inferring, or saying.
Why don't you enlighten us.
rpm goes down. the more torque the less rpm it takes for my Ford to pull your Dodge out of the ditch. lol
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