GTOFAN91

Hey guys I am just curious as to what the advantages are to building these engines. Why would people spend the money on a 347 CI forged engine, when you could get a 383+ CI? Wouldn't the more CI make more power?

Is it possible to achieve 500+ whp NA with the 347 CI setups?

Also I heard many people don't go above 383 CI on these blocks be it cast iron, or aluminium? is this true!

HCI2000SS

iTrader: (2)

Because stroking the motor is going to cost more. That's why a lot of people choone not to do it

MuhThugga

You can only bore the cylinders so much before wall thickness becomes an issue. This is why people step up to a 6.0L block if they want to stroke to a 402 or a 6.2L block for a 416. There just becomes a point where you can't safely gain more cubic inches with a specific block due to physical limitations.

Can you achieve 500 RWHP on a 347? Sure, but it will cost a lot of money and it most likely won't have great street manners. Instead of worrying about peak numbers, worry more about what you want/need the motor to do and what you want/need to use it for.

Darth_V8r

iTrader: (4)

Yes you can get NA 500+ on a 346. Everything has to be very well optimized. Short travel lifters, intake, top notch heads, lots of overlap on the cam, excellent valve train stability. So, let's say you do all that on your 346 and then decide to transfer it all to a 383. You'll get a much broader torque curve, but not much more peak power. However, area under the curve will be greatly improved so the car will be faster.

Now, let's say you step up to a 4" bore with a 6.0. Now you can go to a 408, and you can flirt with 550-600 NA with an even more broader power curve. The 383 limit is only due to the 3.9" bore and 4" stroke. If you start with a 6.0, you have more options. Can also start with a 6.2 and flirt with 427 CI.

Finishing returns on your dollar in the end is why people build HCI and keep stock cubes. It's up to you if it's worth it.

FWIW, my next bottom end will be 408

brobinson216

iTrader: (11)

Always remember this quote: "There is no substitution for Cubic Inches"

Darth_V8r

iTrader: (4)

better known as no replacement for displacement

RollinSScamaro

iTrader: (25)

I've been curious on this same subject being I want to run heads and cam and my motor has almost 130k on it.. makes me nervous changing the heads and cam without touching the cam or rod bearings.. being on a budget not sure if I should go with a 347 or put in the extra money for an 383/402/408 etc.. if i do that i could sell my motor to recover some costs. I plan staying NA but playing around with some nitrous may be an option down the road.. a turbo or supercharger would be the dream.. but I'd need more money to grow on trees lol... im looking for the best bang for the buck for a high 10 sec or low 11 sec car without at ton of weight reduction and great driveability.. hopefully this thread will keep going, I'm in to hear some different options and/Or opinions

JakeFusion

iTrader: (7)

A lot of people just grab the 6L blocks or go to an LS2/3 block and stroke those to get 400+ cid. The additional bore allows for bigger/better flowing heads.

The added stroke to a 3.9" bore doesn't add a lot of power. For the cost difference, it's worth it to go with a 402/408.