Rifleshooter
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Is it possible to get 350 horsepower out of an LA 318 engine? If so how?
350 Hp 318?
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MiradaMegacab
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Boost
Rifleshooter
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I'd prefer not to, but just out of curiosity, how much boost would do the trick?
4speedjim
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Id turbo it. 6lbs boost will blow past 350hp with a stock 318 Magnum. Magnums Stock rated at 220. LA are 120-140hp. The Magnum heads are far superior to la heads so I would start with a Magnum and a $100 Cummins junkyard turbo, new $50 Blow Off Valve with a 6 or 7lb spring and a $50-$400 boost ref. 650 carb and a (not required) intercooler for good measure. No need for anything else as long as you keep the boost below 15Lbs. To do it NA LA you'd need W2s or ported Edelbrock Alum heads, maybe well ported 2.02 Magnum heads. High comp pistons and a good sized cam. You'd lose a lot of daily driver quality going 350hp NA. With a Magnum turbo you dont need to open the motor up, give up idle quality or vacuum for brakes. The torque that breaks seat backs, whistle of the turbo and the manners of Grandma driving to church on Sunday. Its so addicting...
89.Fifth
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Here's a 356HP that used 3.58 stroke crank and cheapo cast pistons.
[SOLD] - MRL 318 Mini Stroker 356hp
[SOLD] - MRL 318 Mini Stroker 356hp
kkritsilas
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There are a number of articles on how to get 400 HP out of a 318. The Hot Rod site has at least two. In general, it involves raising the compression (with pistons and reducing the deck height of the block), getting better heads (EngineQuest usually, or Magnum), and getting the correct cam, pushrods and associated valvetrain parts, intake and 4 barrel carburetor (or third party EFI), and headers. While doing the block work, it goes without saying that the standard stuff like new bearings all around, resizing the rods, and align honing and hot tanking the block should be done, as well as checking to see if the block needs to be bored out due to wear. If using Magnum heads, they will need to be checked for cracks between the valves, a common failure point.
One (of many) articles is here:
318 Engine Build - A Parts Book 400HP 318 - Mopar Muscle Magazine
It is possible to build a streetable 318 that isn't running boost. To run boost reliably, you will have to open up the engine, realistically, just to check on the condition of the bores, bearings, valves, etc.
One (of many) articles is here:
318 Engine Build - A Parts Book 400HP 318 - Mopar Muscle Magazine
It is possible to build a streetable 318 that isn't running boost. To run boost reliably, you will have to open up the engine, realistically, just to check on the condition of the bores, bearings, valves, etc.
4speedjim
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I assumed yoy had 318 block and crank. That adds 13%, 40 Cu In more displacement. More torque/HP comes with more Cu In, everything else equal. Its not impossible to get to 350 hp from a Magnum teeener. You can even get it out of an LA teen. You just need to open your wallet a little further. IIRC 5.9 carbed crate motors make 380. An LA 360 made 140, an LA teen 120. So to answer your question, yes you can make 350hp with a 318.
brotherGood
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Throw magnum heads and a nice cam on your 318..youll be happy. That's what I've got in my car now and it's night and day versus the AHB engine that came out.
That being said..I couldn't tell you what the numbers are, I've not dyno'd it yet, but it pulls hard.
To follow up though, I'm working on dropping a 360 mag in there shortly..but it's because I'm greedy
That being said..I couldn't tell you what the numbers are, I've not dyno'd it yet, but it pulls hard.
To follow up though, I'm working on dropping a 360 mag in there shortly..but it's because I'm greedy
Rifleshooter
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What's the difference between a single plane and a dual plane intake manifold when it comes to performance?
4speedjim
Well-Known Member
watch this
Displacement is one Item, forced induction is another. The more air being pumped by engine = more horsepower - and both methods do just that.
If I was going with a small block, I would go with a stroker crankshaft kit to get 400 (or so) cubic inches. With all else the same, a 400 ci engine will run better than a 318 ci engine.
Get compression ratio back to something respectable, on pump gas (high 8’s or maybe as high as 9.0:1 ratio, or so (higher if using aluminum heads.
Check your gear ratio. Driving a car with 2.2 ratio gears is for the birds (like what I have in my ’86 5th Ave). Get something like 2.9 or 3.2 ratio and that will wake any engine up, all by itself.
I have two similar cars: ’86 5th Ave and a ’77 Volare Wagon. Both are 318 2-bbl automatics. The wagon has 2.94 gears and 2.2’s in the 5th Ave. Otherwise the two cars are the same.
From a stop, the wagon will literally go circles around the 5th Ave. When both are at say 50 MPH, they run about the same.
Gears might give you more bang for your buck, early on.
BudW
If I was going with a small block, I would go with a stroker crankshaft kit to get 400 (or so) cubic inches. With all else the same, a 400 ci engine will run better than a 318 ci engine.
Get compression ratio back to something respectable, on pump gas (high 8’s or maybe as high as 9.0:1 ratio, or so (higher if using aluminum heads.
Check your gear ratio. Driving a car with 2.2 ratio gears is for the birds (like what I have in my ’86 5th Ave). Get something like 2.9 or 3.2 ratio and that will wake any engine up, all by itself.
I have two similar cars: ’86 5th Ave and a ’77 Volare Wagon. Both are 318 2-bbl automatics. The wagon has 2.94 gears and 2.2’s in the 5th Ave. Otherwise the two cars are the same.
From a stop, the wagon will literally go circles around the 5th Ave. When both are at say 50 MPH, they run about the same.
Gears might give you more bang for your buck, early on.
BudW
Rifleshooter
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I have already taken the gear ratios into consideration. I currently have the a230 3 speed trans in with my slant six and a 2.76 rear gear. But I just got ahold of an A833od trans and I plan on putting that in with the 318 and I plan on putting a 3.55 gear and a 8 1/4 rear all when I drop the 318 in at the same time.
AJ/FormS
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STOP!
a 350 hp 318 will hate that od trans
To get 350 out of that 318 will mean lots and lots of rpm, and that means a big cam, and that means sacrificing low speed torque.And the trans will not have a decent ratio for around town cruising.
That od trans has ratios that are very wide and work best on hi-torque/low rpm engines, like slantys and stock 318s.
For decent acceleration at 30 mph, you need about a 6.80 ratio final drive. With 3.55s this is a second gear of 1.92. But the od box has only a 1.67, so you get a second of 1.67 x 3.55=5.93, and so your rpm with 26.5s will be 32mph=2400 Guess how much power your HOT318 will have at that rpm. I'll tell you; squat. Ok but say you downshift. Now your Rs will be 4550 and your teener is a screaming banshee, for about 1 or 2 seconds and then you're back into the lame-oh second gear.It's not good.
So that leads to the question of why are you targeting 350 hp?
There are far cheaper and better ways to get there, than starting with a 318.
a 350 hp 318 will hate that od trans
To get 350 out of that 318 will mean lots and lots of rpm, and that means a big cam, and that means sacrificing low speed torque.And the trans will not have a decent ratio for around town cruising.
That od trans has ratios that are very wide and work best on hi-torque/low rpm engines, like slantys and stock 318s.
For decent acceleration at 30 mph, you need about a 6.80 ratio final drive. With 3.55s this is a second gear of 1.92. But the od box has only a 1.67, so you get a second of 1.67 x 3.55=5.93, and so your rpm with 26.5s will be 32mph=2400 Guess how much power your HOT318 will have at that rpm. I'll tell you; squat. Ok but say you downshift. Now your Rs will be 4550 and your teener is a screaming banshee, for about 1 or 2 seconds and then you're back into the lame-oh second gear.It's not good.
So that leads to the question of why are you targeting 350 hp?
There are far cheaper and better ways to get there, than starting with a 318.
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Rifleshooter
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I'm choosing a 318 because I don't want the 360 or 340(weren't in the 80s anyway), aside from that. I'm targeting the 350 range because I want power yes, but I don't want to be overdoing it to the point of blowing the rear every so thousand miles, I want a good street performance engine
AJ/FormS
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So, I'll tell you a secret
3.55s are a great middle of the road gear. And the od trans can be made to work quite well on a low-rpm/hi torque engine.
If you insist on keeping the teener, then you're gonna have to boost it.
Or you can heave that od box, go back to the A230, and redefine why you want 350 hp.
To get that 350, means sacrificing low-speed driveability. You can't have both with a 318 and 3 gears. Not even with 4 close ratio gears. You will need 5 gears. Think Mustang;302 engine and 5 gears. There is no way around this.
But if you broaden your horizon to a 360, then this all works out so perfect.
360hp is easy for a 360 with a small cam and good heads. Then you can use that A230 and the 3.55s or even 3.23s.
Or you can use the od and 3.91s. These will get you a second gear of 1.67 x 3.91 =6.53 which is very nice for blasting off at 32mph=2650 with a mild 360 cuber. Your hiway gear will be 3.91 x .73=2.85 so 65=2350
and your starter gear is a tire-frying 3.91 x 3.09=12.08 which will take you to 35mph easy enough, at about 5500.It's way more starter gear than you need,but that's the way it is with that od-box.
Stop worrying about blowing up the 8.75, properly set up and on the street, it will never happen. I've been pumping over 400hp into mine with 295s back there for probably 100,000 miles or more and well over 10 years; it's a non-issue.
But if you just want to have a lil fun with a 318, then forget the 350hp target for a bit.
On the street, you spend like 85% of the time at under 3500 rpm. A 350 hp engine will not make 350 until maybe 5600rpm or more, which is way down the road. No you need power from idle to 3500 where 85% of your driving is gonna be.Am I wrong? I'd be willing to bet that 95% of the time will be spent below 4000 rpm.
Ok so how fast will you be going at 3500 rpm with the A230 and 3.55s? Well the math says about 26mph. With the right small cam, you will be very near to your torque peak and ready to blast off. At 5000/36mph will be the 1-2 shift. The Rs will fall to 2900 and and if you had a 350 hp teener, you'd be sunk. But the small-cam teener gets right to work pulling that up, and by 63 mph is again at 5000rpm.
So while the 350hp engine might get you to 60 faster than the 275 one, it probably won't be with the A230 and 3.55s, and it won't have near the driveability below 3000rpm. And it will suck gas supremely on the hiway.
3.55s are a great middle of the road gear. And the od trans can be made to work quite well on a low-rpm/hi torque engine.
If you insist on keeping the teener, then you're gonna have to boost it.
Or you can heave that od box, go back to the A230, and redefine why you want 350 hp.
To get that 350, means sacrificing low-speed driveability. You can't have both with a 318 and 3 gears. Not even with 4 close ratio gears. You will need 5 gears. Think Mustang;302 engine and 5 gears. There is no way around this.
But if you broaden your horizon to a 360, then this all works out so perfect.
360hp is easy for a 360 with a small cam and good heads. Then you can use that A230 and the 3.55s or even 3.23s.
Or you can use the od and 3.91s. These will get you a second gear of 1.67 x 3.91 =6.53 which is very nice for blasting off at 32mph=2650 with a mild 360 cuber. Your hiway gear will be 3.91 x .73=2.85 so 65=2350
and your starter gear is a tire-frying 3.91 x 3.09=12.08 which will take you to 35mph easy enough, at about 5500.It's way more starter gear than you need,but that's the way it is with that od-box.
Stop worrying about blowing up the 8.75, properly set up and on the street, it will never happen. I've been pumping over 400hp into mine with 295s back there for probably 100,000 miles or more and well over 10 years; it's a non-issue.
But if you just want to have a lil fun with a 318, then forget the 350hp target for a bit.
On the street, you spend like 85% of the time at under 3500 rpm. A 350 hp engine will not make 350 until maybe 5600rpm or more, which is way down the road. No you need power from idle to 3500 where 85% of your driving is gonna be.Am I wrong? I'd be willing to bet that 95% of the time will be spent below 4000 rpm.
Ok so how fast will you be going at 3500 rpm with the A230 and 3.55s? Well the math says about 26mph. With the right small cam, you will be very near to your torque peak and ready to blast off. At 5000/36mph will be the 1-2 shift. The Rs will fall to 2900 and and if you had a 350 hp teener, you'd be sunk. But the small-cam teener gets right to work pulling that up, and by 63 mph is again at 5000rpm.
So while the 350hp engine might get you to 60 faster than the 275 one, it probably won't be with the A230 and 3.55s, and it won't have near the driveability below 3000rpm. And it will suck gas supremely on the hiway.
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AJ/FormS
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Here's another secret
a 275 hp 360 is so cheap and easy, it's ridiculous. And it has even more lowspeed power. So you can give up a lotta rear gear if you want to hit the hi-way. And that almost always means more miles per dollar spent .
So get this; starting with the 360, the 275hp rebuild is waaay cheaper,and running it is cheaper, and it can get you more miles per dollar,and it will have more low-speed performance, more midrange, and more WOT power at every rpm , than a 275hp teener.
If you spend the same amount of money on the 360 build that you would on the teener it will probably make in excess of 360/318= 13% more power, and a lot more torque than that.
In fact, just by adding a 4bbl and headers,it's hard not have at least 275 hp with a 360. Toss in a cam and some compression and she's over 300. Add some nice heads and 350 is right there. A little more cam and she's kissing 400. And all the while, the bottom end torque is still stronger than the stock teener.
a 275 hp 360 is so cheap and easy, it's ridiculous. And it has even more lowspeed power. So you can give up a lotta rear gear if you want to hit the hi-way. And that almost always means more miles per dollar spent .
So get this; starting with the 360, the 275hp rebuild is waaay cheaper,and running it is cheaper, and it can get you more miles per dollar,and it will have more low-speed performance, more midrange, and more WOT power at every rpm , than a 275hp teener.
If you spend the same amount of money on the 360 build that you would on the teener it will probably make in excess of 360/318= 13% more power, and a lot more torque than that.
In fact, just by adding a 4bbl and headers,it's hard not have at least 275 hp with a 360. Toss in a cam and some compression and she's over 300. Add some nice heads and 350 is right there. A little more cam and she's kissing 400. And all the while, the bottom end torque is still stronger than the stock teener.
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AJ/FormS
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If you're really married to the teener,I recommend; boost it,and get an automatic.
Although..............................that od box might actually work now. Yeah!, I think it just might.
Just don't unleash the beast in OD gear, unless you are close to home, cuz walking ain't my cup-O-tea anymore,lol.
Yeah, remember when I said that a good second gear ratio was 6.80ish? Well that was normally aspirated thinking. With a boosted engine, you maybe wouldn't need that much. Now I'm thinking that 1.67second gear x 3.55=5.93 would be enough. And this gear will get you 60mph@ 4500, so it's a bolt it onto a stock 318 and let her buck!
And now you have Dial-a-Torque/Dial-a-Power. Just keep cranking it, 'til it blows up. Just keep a spare teener in the garage, I mean they are so cheap to buy.
Although..............................that od box might actually work now. Yeah!, I think it just might.
Just don't unleash the beast in OD gear, unless you are close to home, cuz walking ain't my cup-O-tea anymore,lol.
Yeah, remember when I said that a good second gear ratio was 6.80ish? Well that was normally aspirated thinking. With a boosted engine, you maybe wouldn't need that much. Now I'm thinking that 1.67second gear x 3.55=5.93 would be enough. And this gear will get you 60mph@ 4500, so it's a bolt it onto a stock 318 and let her buck!
And now you have Dial-a-Torque/Dial-a-Power. Just keep cranking it, 'til it blows up. Just keep a spare teener in the garage, I mean they are so cheap to buy.
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AJ/FormS
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Hyup, that's just the way of it.......
The A833 with overdrive is close (not quite – but good enough for illustration) to your current A230, gear ratio wise - but with an overdrive gear.
I would agree with AJ/FormS that for a /6 or stock 318 (stock 360?) the A833 with overdrive will work great – for it is considered to be an economy (and not a high performance) transmission.
Now the A833 without overdrive – is a whole another animal.
1st gear and “drive” (1:1 ratio, which would be 4th gear in non-overdrive or 3rd gear with overdrive) would be about the same ratios. The difference is you have either 1 or 2 gears to shift to get to “drive” (1:1 ratio). What performance engines like, is more gears to keep you in the powerband.
What would be excellent would be an A833 4-speed with another/additional gear for overdrive (ie: a 5-speed) – that way you have the best of both worlds.
The A833 w/overdrive has a purpose (economy) – and it is not for high performance cars.
I have mentioned it before, my brother is building a pair of ‘Cuda’s, one Hemi and other 440-6 (both non-original cars). The 440-6 - he has pair of A833’s, one of which is overdrive so he can drive the car and get better mileage with it/less wear and tear. http://www.forfmjbodiesonly.com/classicmopar/threads/the-long-and-short-tails-of-a-4-speed-od-with-the-j-body-console.6800/#post-75364
(He has a lot more disposable cash than I have).
He has told me that the 440-6 “get up and go” is a “no go” with the overdrive installed, but at least driving the car is far more fun than trailering it.
BTW, don’t get into a race with a built 440 6-pack with overdrive, on the interstate. The car is out of your sight, before you know it.
BudW
I would agree with AJ/FormS that for a /6 or stock 318 (stock 360?) the A833 with overdrive will work great – for it is considered to be an economy (and not a high performance) transmission.
Now the A833 without overdrive – is a whole another animal.
1st gear and “drive” (1:1 ratio, which would be 4th gear in non-overdrive or 3rd gear with overdrive) would be about the same ratios. The difference is you have either 1 or 2 gears to shift to get to “drive” (1:1 ratio). What performance engines like, is more gears to keep you in the powerband.
What would be excellent would be an A833 4-speed with another/additional gear for overdrive (ie: a 5-speed) – that way you have the best of both worlds.
The A833 w/overdrive has a purpose (economy) – and it is not for high performance cars.
I have mentioned it before, my brother is building a pair of ‘Cuda’s, one Hemi and other 440-6 (both non-original cars). The 440-6 - he has pair of A833’s, one of which is overdrive so he can drive the car and get better mileage with it/less wear and tear. http://www.forfmjbodiesonly.com/classicmopar/threads/the-long-and-short-tails-of-a-4-speed-od-with-the-j-body-console.6800/#post-75364
(He has a lot more disposable cash than I have).
He has told me that the 440-6 “get up and go” is a “no go” with the overdrive installed, but at least driving the car is far more fun than trailering it.
BTW, don’t get into a race with a built 440 6-pack with overdrive, on the interstate. The car is out of your sight, before you know it.
BudW
MoparKidD-4
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Here's my idea: Get a nice-running 5.2L Magnum on Craigslist, they go for $100-200 around here and check the short block for cylinder bore wear, usually there will be little to none if it was at least half taken-care-of. Have the heads checked for cracks between valve seats, if no cracks do a performance valve job and if you're able a mild porting; stock valves are fine. If there are cracks some say to junk them some say they're OK, you're call but there's the EngineQuest replacement Magnum heads available for $330 each last time I checked. Get a replacement hydraulic roller cam, either regrind or new, in the 220* at .050" duration range, maybe a tad more depending on the rear-end gearing. Add Air-Gap dual plane intake (or the Chinese Crosswind), 650-cfm carb, 1-5/8" headers, and that thing will shred pavement all day long. You can even bolt LA valve covers onto the heads and paint the whole thing black (maybe blue in your case?) for the "stock" look.
