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Discussion Starter #1
Wanting to bore out engine. 289 in 68 coupe. No super serious thoughts on doing but curious on cost and how much hp would add... It’s at ab 300 rn

thanks
In case anybody wanted to see....
759924
 

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Just an overbore will add little hp. The machine work is probably the cheapest part. New pistons and the rebuild will cost you. Absolutely no reason to pull an engine down just to bore it.
 
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Not what you want to do. Boring out is only when rebuilding due to wear. You might get 5hp strictly boring .060 which would be the max you'd want to do. Maybe you meant stroke but I think even that is not advisable for a 289
 

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Discussion Starter #4
Wanting to bore out engine. 289 in 68 coupe. No super serious thoughts on doing but curious on cost and how much hp would add... It’s at ab 300 rn

thanks
In case anybody wanted to see.... View attachment 759924
Just an overbore will add little hp. The machine work is probably the cheapest part. New pistons and the rebuild will cost you. Absolutely no reason to pull an engine down just to bore it.
Okay thanks
 

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Not what you want to do. Boring out is only when rebuilding due to wear. You might get 5hp strictly boring .060 which would be the max you'd want to do. Maybe you meant stroke but I think even that is not advisable for a 289
Why is it not advisable
 

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Well I'm not an expert on stroking engines but I believe the cylinder walls are a little short in the 289. When you stroke the engine the pistons will have a longer stroke and come down lower in the cylinder. A 302 is better suited for stroking. If you are looking for horsepower there are other cheaper ways to get more.
 

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Well I'm not an expert on stroking engines but I believe the cylinder walls are a little short in the 289. When you stroke the engine the pistons will have a longer stroke and come down lower in the cylinder. A 302 is better suited for stroking. If you are looking for horsepower there are other cheaper ways to get more.
Any other suggestions for producing more hp/ lb ft? Sorry for randomness.
 

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Not without knowing what you have or the budget but intake, exhaust, cam and heads are all good place to start.
I’m 99% sure it has all of those upgraded
And speaking on budget, I’m not super serious ab it and don’t need right now but I’d like to get some ideas stirring but know nothing about it. And thanks for ur help so far
 

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Galactics, tell us what the engine has done to it now, and what supporting systems you have, and we'll help you figure it out. Yes, you CAN stroke the 289. The difference in cylinderwall length is minimal, sometimes ~ .060, sometimes ( usually ) no measurable difference. If you want to stroke to 347, you can. Tell us what heads, cam, intake, and exhaust you have, and I'll help you choose some pieces. I retired from the engine building shop last summer. what kind of power are you looking for ? and how much can you spend ? LSG
 

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Galactics, tell us what the engine has done to it now, and what supporting systems you have, and we'll help you figure it out. Yes, you CAN stroke the 289. The difference in cylinderwall length is minimal, sometimes ~ .060, sometimes ( usually ) no measurable difference. If you want to stroke to 347, you can. Tell us what heads, cam, intake, and exhaust you have, and I'll help you choose some pieces. I retired from the engine building shop last summer. what kind of power are you looking for ? and how much can you spend ? LSG
Honestly feel dumb for posting this now and wasting time. As far as I know it has 302 heads, upgraded cam, aftermarket exhaust, and Holley 4 barrel. I’d like to know the Max HP we could pull from it and on spending I’m not looking for something immediate so I’d be able to save up over time. So I don’t have particular price range
 

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First, welcome to the hobby. Your car looks nice. If you do the work yourself you can think in terms of:
  • Aluminum heads $2,000
  • New cam $400
  • Headers $300
  • Rear end gear change $1,000
  • Stroker kit and machine work $2,500
Pay to have the work done and you can add 50% to that.

Those are lower end prices. One can spend $1k on headers if they want.
 

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Max horsepower? Well, you can technically push a 289 to well over 400 HP, but it will be pretty useless at low RPMs and you risk splitting the block in two. (Not talking about a stroked engine. That's not a 289 anymore.)

Again, give us an idea about what you want to do with your car and we can help you out. I know the TV car shows always drop in 500+ horsepower engines into almost everything. That sounds way cool, but in a '68 Mustang, you couldn't do much with that kind of power unless you completely rebuilt the car. You'd just melt the rear tires and likely wrap it around a telephone pole. :D

My 351 Cleveland dyno'd at 266 HP at the wheels. That was before I did any real tuning. I'm sure I could coax much more with a different intake, bigger carb and such. But to be honest, right now the car is more than fast enough for street use. If I get on it at all, I'm doing 100 MPH by the time I hit third gear. Yeah, 266 HP sure doesn't sound like much, but it's still more than I need in a 1970 fastback. If you're drag racing or road racing a lot, that's a different story.
 

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Boring a 302 .030" only adds 4 cu. in. Stroking a 302 .250", which requires a new crankshaft, adds 25 cu. in.
 

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You really need to figure out what you have first. Replacing those heads with having the right intake and exhaust combination. Could give you a big increase in power. If the intake/ exhaust combo is not optimal. You may see dismal results working together. If your engine runs good already. You may see a big performance boost with lower rear end gears. Everything needs to work together to get what you want.
 

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Yes, what is it now? I highly doubt its 300hp or even 250 or it would be hella fun in the right hands.
Is it really a 289? Is it OE to the car? NO? Then get a junkyard 302 roller and build it up over time like a savings account or...
Get some lower rear gearing and advance the timing:)
 

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1965 Mustang Fastback GT350-Tribute Restomod. 2019 Shelby GT350.
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Here's an option to get you some ball-park performance numbers and pricing:
If you have a solid 289 bottom-end, you could look at a top-end kit (heads, intake, cam, with further options for ignition & fuel system). There are a variety of kits with a wide-range of prices and performance. I did this using Edelbrock products. Just search for "Edelbrock top-end kit 289" and look at the Edelbrock and Summit Racing websites (among others). This approach is not the least expensive, but the vendors can demonstrate their performance results, you have a documented plan for installation and it removes most of the guesswork in configuring your system.
 
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