Big horsepower 318 builds

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One other thin about the 318. Many years ago, Hot Rod or Car Craft magazine (I don't remember which), printed an article that challenged builders to get maximum HP with a $2500 budget from a Mopar 318, 350 Chebby and a Small block Ford (351 Windsor I think). The 318 won. I don't remember any other details, but the 318 won.
 
gregcon said:
"See hear is the faults perpetuation of bullcrap..... start right off saying you don't know much about them and then go on to say how they're going to lose a valve in a couple of years... Solely because the fact that they're Chinese LOL."


See how people get confused so easily? I knew nothing about the heads...my comments about dropping valve seats was a generic one...though from years of experience I know that is one area where aluminum heads fail if they are not done right. And porosity is another issue. Poor valve material is another.

My standard guess is anytime there is a cheaper product, it's Chinese. I don't even know where Edelbrock makes their heads....I assume it's the USA but I could be wrong. I'll tell you one thing....if the Edelbrocks are USA I'd buy them over a Chinese product regardless of all else.

America is a funny place...if you insult the average American's football team, he's ready to kick your ***. But take sides with our country's single biggest enemy? Perfectly OK if it saves you 7%. But I've been saying that for over 30 years and it never seems to do any good. I just look forward to the day my grandkids rush in the door and tell with great excitement that they were chosen to wash Mr. Wu's Cadillac for the entire week.
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So your standard guess is the Chinese make an inferior product? No way possible the Chinese could make a better product? We're not talking 7% here we're talking like a hundred and ten or 120% cheaper... $799 for one head with bad casting as apposed to 700 for two heads with a superior casting... You can work out the percentage on that... my car is running just fine with the Chinese heads... But hands down my favorite is the Chinese air conditioning LOL....
 
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Also, the theory "you just have to spin 318's higher" is just a theory.
 
Here is a way to go, find your own valves and springs and build your own 318 heads. I could see doing that.

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Jumping back in...

George Jets said:
Like that, that is a great deal.

I am sure the 2.02 valves by themselves are not cheep. Exhausts should be the stock 360 exhaust .160 valves, those are readily available.
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The valves are 11/32 stem. Stock 360 3/8 stem ex will not work. SB chevy +.100 long In and Ex will work.
 
318willrun said:
Also, the theory "you just have to spin 318's higher" is just a theory.
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I don't get this one, don't know why you would say that?

To me there two main ways to go about building an engine, for a certain powerband and gearing or for a certain hp level and gear and stall to work with the final powerband results. To a point most are a combo of the two.

The 1st one say you pick 3.23 and idle to 5000 rpm with peak hp being about 5000 rpm, obviously since rpm is fixed torque is the only main way you can build NA power so the bigger the engine the more hp you'll have most street type engine fall into category.

2nd is to pick say 500 hp and pick a displacement and build.

So a 318 vs 360 vs 408 you would have to displace a certain amount of air, there's a rule of thumb saying about 1.4 cfm for every hp, not carbureted but actual displacement (1.4cfmx500hp=700cfm) so if you run a 390 cfm carb or a 1000 cfm carb the engine is gonna pull 700 ish cfm's through either.

At 100% VE using cid x rpm / 3456 = cfm

a 318 would need to spin 7608 rpm to displace 700 cfms
a 360 would need to spin 6720 rpm to displace 700 cfms
a 408 would need to spin 5929 rpm to displace 700 cfms

Obviously depend on how well you design your combo they can overlap eg. a poorly built 360 peaking at 7200 rpm and a well put together 318 peak at 7100 rpm but I don't think you could build the 408 terrible enough for the 318 and it to have similar powerband.

So I guess yes there's exception and there's enough variables to make it, "it's just a theory", but it's generally true smaller needs to spin higher.
 
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273 said:
I don't get this one, don't know why you would say that?

To me there two main ways to go about building an engine for a certain powerband and gearing or for a certain hp level and gear and stall to work with the final powerband results. To a point most are a combo of the two.

The 1st one say you pick 3.23 and idle to 5000 rpm with peak hp being about 5000 rpm, obviously since rpm is fixed torque is the only main way you can build NA power so the bigger the engine the more hp you'll have most street type engine fall into category.

2nd is to pick say 500 hp and pick a displacement and build.

So a 318 vs 360 vs 408 you would have to displace a certain amount of air, there's a rule of thumb saying about 1.4 cfm for every hp, not carbureted but actual displacement (1.4cfmx500hp=700cfm) so if you run a 390 cfm carb or a 1000 cfm carb the engine is gonna pull 700 ish cfm's through either.

At 100% VE using cid x rpm / 3456 = cfm

a 318 would need to spin 7608 rpm to displace 700 cfms
a 360 would need to spin 6720 rpm to displace 700 cfms
a 408 would need to spin 5929 rpm to displace 700 cfms

Obviously depend on how well you design your combo they can overlap eg. a poorly built 360 peaking at 7200 rpm and a well put together 318 peak at 7100 rpm but I don't think you could build the 408 terrible enough for the 318 and it to have similar powerband.

So I guess yes there's exception and I guess there's enough variables to make it, "it's just a theory", but it's generally true smaller needs to spin higher.
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To get out of the minds "318 vs ***", lets look at a single cubic inch. 360 per say. Some build them to shift at 7200 rpms all day and do it going 11's in the 1/4. Some build them and shift at mid 6k and run mid 9's. Why would that be?? Because it's about how well the heads are flowing, and a cam to match, and a intake/carb to sit on top of it that compliments the design of the build. I bet my 318 makes more power at 5000 rpms than a stock '73 340, and I have less of just about everything. Why would my smaller engine make as much or more power at the same rpm??? Is it my smaller valves? Or less compression? I don't say this sarcastically, I say it because there is a theory that one HAS to spin the daylights out of the smaller engine to make equal power. Simply not the truth.
 
318willrun said:
Also, the theory "you just have to spin 318's higher" is just a theory.
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Theory ? Please explain your theory. lol
My theory is, a 318 will have to spin 8K with 280 - 300 cfm head with a 600 lift cam and 11.1 comp to produce 500 hp.
 
fishmens67 said:
Theory ? Please explain your theory. lol
My theory is, a 318 will have to spin 8K with 280 - 300 cfm head with a 600 lift cam and 11.1 comp to produce 500 hp.
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Not with a ebay turbo, I bet 5500 rpms gets it done .... :poke::poke:
 
273 said:
The 318 in this article only spins 6500 rpm to make 477 hp, don't thing you would need another 1500 rpm's to make the last 23 hp.

Iron-Headed Mopar 318 Magnum Engine- Popular Hot Rodding Magazine

But it's a very well put together engine.
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And that motor made a lot of torque as well. To me, there has to be a ton more thought in a smaller motor, not necessarily a ton more rpm's. For instance, a 440 has a lot more "wiggle room", if you will, for error in the build and still make decent power. Throw a few errors in a 273 build and you might get beat by a good super six in a volare... lol.
 
PRH said:
My take on it is....... unless it was built to fit within some specific set of rules....... or someone took it on as a personal quest....... I look at it as.....why would I do that?
(When a 500hp 408/416 will be easier and likely cheaper).

It’s going to require a fairly high level of effort to end up with a 500hp 318.
From a hp/ci standpoint, it’s like building a 446 at real close to 700hp.

I have built a few 440’s that got into the 700hp range(a bit over 1.5hp/ci).
Those were fairly well thought out builds with good cylinder heads and fairly stout cams.

I’d be happy to follow along though, if someone decided to “go for it” with the 318.
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Don't hold your breath...:rolleyes:..
This entire thread is just food for controversy...:(...
 
318willrun said:
To get out of the minds "318 vs ***", lets look at a single cubic inch. 360 per say. Some build them to shift at 7200 rpms all day and do it going 11's in the 1/4. Some build them and shift at mid 6k and run mid 9's. Why would that be?? Because it's about how well the heads are flowing, and a cam to match, and a intake/carb to sit on top of it that compliments the design of the build. I bet my 318 makes more power at 5000 rpms than a stock '73 340, and I have less of just about everything. Why would my smaller engine make as much or more power at the same rpm??? Is it my smaller valves? Or less compression? I don't say this sarcastically, I say it because there is a theory that one HAS to spin the daylights out of the smaller engine to make equal power. Simply not the truth.
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The problem with ANY discussion of RPM is the simple fact that even in 2020, 7000 RPM is considered “race” engine RPM. It’s barely an acceptable RPM for street/strip cars.

Cue everyone running “fast” shifting at 6200. It doesn’t change the fact that RPM makes horsepower.
 
yellow rose said:
The problem with ANY discussion of RPM is the simple fact that even in 2020, 7000 RPM is considered “race” engine RPM. It’s barely an acceptable RPM for street/strip cars.

Cue everyone running “fast” shifting at 6200. It doesn’t change the fact that RPM makes horsepower.
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Do you have a 500hp recipe for a 318 at 6200-7000 rpm
 
yellow rose said:
The problem with ANY discussion of RPM is the simple fact that even in 2020, 7000 RPM is considered “race” engine RPM. It’s barely an acceptable RPM for street/strip cars.

Cue everyone running “fast” shifting at 6200. It doesn’t change the fact that RPM makes horsepower.
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IF the combo is set up to make HP "up there"..... IF not, then power drops off and the car slows up. I've played "shifting" games at the strip, and there is a happy spot for every engine. Can you spin it more??? Yep! I spun a 340 7200 RPM's and slowed up a 1/2 second vs 6000 rpms. It's wherever the power band is set up to run. BUT, you don't NEED 8500 rpm's to run 9's. To many of them doing it at 6500- 7k.
 
318willrun said:
IF the combo is set up to make HP "up there"..... IF not, then power drops off and the car slows up. I've played "shifting" games at the strip, and there is a happy spot for every engine. Can you spin it more??? Yep! I spun a 340 7200 RPM's and slowed up a 1/2 second vs 6000 rpms. It's wherever the power band is set up to run. BUT, you don't NEED 8500 rpm's to run 9's. To many of them doing it at 6500- 7k.
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You won't be crossing the stripe in the 9's with a 318 under 7000 rpm NA . Not going to happen. :D
 
fishmens67 said:
You won't be crossing the in the 9's with a 318 under 7000 rpm NA . Not going to happen. :D
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You don't think that 477 hp 318 @ 6500 rpm's wouldn't go 9's in a rail (under 7k and N/A in the 9's) :poke::poke:

.. I guess I was talk'n "motors in general", not 318 specific (I know, off topic a little).
 
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