347 forged bottom end Pros & Cons
347 forged bottom end Pros & Cons Are any of you guys running a 347 forged bottom end on nitrous? I am asking because I wanted a forged bottom end but didn't want to touch the block. So I think this would be my only route. I also will be running a MS4 camshaft and a 250 shot on a progressive system. Any info will be helpful. 
Thanks
Thanks
Well there are a number of force inducted 347 holding 800 hp on a stock crank and aftermarket pistons and rods. The block would need a slight hone for the new rings and pistons and thats about it. You can dress it up with arp bolts and so on with clevite beraings. The one thing I would look at is the off set for a 408. Lets say a 347 comes in at 3400 wich it shouldnet but you can get a 408 at that price the cam might not be as great but a 250 shot hell it wont matter lol.
Yes a 6.0 Iron Block would be needed for the 408. Forged 347s will work great for what you are looking to do, but Outlawz has it right, you will have to have the block honed for any pistons strong enough to take that much nitrous. At that point it is a good idea to look into the 408 because price won't be that different and the stroker will add quite a bit of power and torque to the setup. Feel free too PM me or give us a call up at the shop if you have more questions.
Actually Im not going to shoot a 250 till later on down the road. I want to be able to run on motor and just have nitrous for insurance maybe a 150-200 wet for awhile. So with a 6.0 block will I have to bore it to? Whats my limit with the stock 346 if I was to do a head and cam with a 150-200 shot. If I get good rod bolts want that bottom end hold up for awhile with a good tune. Want to be able to drive the car daily if I want. Will be powered by a TH350.
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From: Where our street cars are faster than your racecars..Mississippi
my boyi had a stock 346 with prc 2.5 heads and a ms3 cam with ls6 intake i was spraying a 100 shot and was in the 6.xx through the 1/8 withe a 3500 stall 4l60e but then a stock rod bolt let go..
383 it will be now..lol
i don't want the added weight of the iron block (75lbs or so)
383 it will be now..lol
i don't want the added weight of the iron block (75lbs or so)
Last edited by denali_on_26's; Aug 9, 2009 at 06:35 PM.
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The pros of a 347 - cheaper when you use your block and crank, can spin big rpm's quick, hold up to a big shot.
the cons - no more hp or torque as the stock shortblock because theres no added cubes. a little extra weight from forged peices (not a con really just thought i'd mention it)
Personally if budget wasn't an issue i would look for more cubes. Especially since you say your going to run on motor most of the time. A forged 347 wont do anything for you running N/A. A 408 will make more than enough hp to make up for the 75 pounds, plus if you dont want the weight go with a LS2 402.
the cons - no more hp or torque as the stock shortblock because theres no added cubes. a little extra weight from forged peices (not a con really just thought i'd mention it)
Personally if budget wasn't an issue i would look for more cubes. Especially since you say your going to run on motor most of the time. A forged 347 wont do anything for you running N/A. A 408 will make more than enough hp to make up for the 75 pounds, plus if you dont want the weight go with a LS2 402.
My 347 combo works great for what it is. Just depends on your future plans/budget. Anyways, you're gonna have to touch the block to get a 3.905 bore for a decent set of pistons.
Yes a 6.0 Iron Block would be needed for the 408. Forged 347s will work great for what you are looking to do, but Outlawz has it right, you will have to have the block honed for any pistons strong enough to take that much nitrous. At that point it is a good idea to look into the 408 because price won't be that different and the stroker will add quite a bit of power and torque to the setup. Feel free too PM me or give us a call up at the shop if you have more questions.
Why is it whenever a customer wants a smaller CI. build you and all the other people at Texas Speed hound the person until they spend more money for what you "suggest is best". He may not want that many cubes he can get to his goals with forged bottom end 347 which I am sure he is prepared to hone and add stronger pistons instead of spending more on a 408. Just venting for the night I just feel and hear it and see it in EVERY one of this vendors threads and about 4 already tonight that I have read. Sorry for the derail guys.
For the amount of money you are spending, you could spend a tiny bit more, and make as much hp N/A with a bigger motor than he could with the 347 on spray.... Most people will just save up a little longer for the added HP...Which is ALOT
I think everyone knows that the forged 347 will be cheaper and if that what is budget allows than go for it, with a nice shot it will be fun.
But to run the car N/A afterwards there wont be a difference than with the stock bottom end. I dont think anyone is pushing him to do anything just pointing out the different options.
Hell he could pick up a used lq4 for a couple hundred and build a forged 370 using the stock crank atleast that way when he runs N/A there will be a performance gain.
And i think when everyone says the 408 is only a couple hundred cheaper than a forged 347, they are talking about buying a whole shortblock 347 vs a shortblock 408.
But to run the car N/A afterwards there wont be a difference than with the stock bottom end. I dont think anyone is pushing him to do anything just pointing out the different options.
Hell he could pick up a used lq4 for a couple hundred and build a forged 370 using the stock crank atleast that way when he runs N/A there will be a performance gain.
And i think when everyone says the 408 is only a couple hundred cheaper than a forged 347, they are talking about buying a whole shortblock 347 vs a shortblock 408.
The pros of a 347 - cheaper when you use your block and crank, can spin big rpm's quick, hold up to a big shot.
the cons - no more hp or torque as the stock shortblock because theres no added cubes. a little extra weight from forged peices (not a con really just thought i'd mention it)
Personally if budget wasn't an issue i would look for more cubes. Especially since you say your going to run on motor most of the time. A forged 347 wont do anything for you running N/A. A 408 will make more than enough hp to make up for the 75 pounds, plus if you dont want the weight go with a LS2 402.
the cons - no more hp or torque as the stock shortblock because theres no added cubes. a little extra weight from forged peices (not a con really just thought i'd mention it)
Personally if budget wasn't an issue i would look for more cubes. Especially since you say your going to run on motor most of the time. A forged 347 wont do anything for you running N/A. A 408 will make more than enough hp to make up for the 75 pounds, plus if you dont want the weight go with a LS2 402.
I am in the same position. Trying to decide which way to go. What about heads on the 408. Will PRC Satge 2.5 be big enough?? Will my 1 3/4 inch Kooks be big enough? Will my Yank SS 4000 need to be re-stalled? These are the questions I have. Sorry to Hi-jack your thread, But these are questions I think will help you as well.
With how tight money is now, unless you have a real low mileage engine or a killer price you might be holding on to it for a while. So I wouldn't necassarily figure the selling price of the old setup into the price of buying the new one, you never know what your gonna get for it or if your even going to be able to sell it.
I went with a forged 347 from TSP for my forced inducton set up because The blower is alway there making the same power at WOT. If you don't want to spray all the time I'm with the rest of them... Go bigger cubes. If 425-450 rwhp N/A is good for you, go with the 347ci and a nice head/cam combo then hit it with the go gas from time to time.
I just want to have a good bottom end to handle a 200 shot max. If i ever wanted to go that big Im thinking I will just shoot a 150 until I start getting beat. As long as I am mid 11's N/A & mid to lo tens on the button I will be happy. Can I go mid to lo 10's with a 347 bottom end and a Heads and cam package? (I'm thinking a head and cam package from TSP) MS3 or 4.
Last edited by HitmanLS1; Aug 11, 2009 at 05:15 PM.