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Old Jan 13, 2006 | 02:14 AM
  #1  
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Default THE PLAN.. u judge

alright.. i have a 78 red vette and im planning on making it into a real mean street machine... its got a goodwrench 350 4 bolt main good for about 220 hp (its a replacement engine).

my plan is to make that into a 383 (or just buy a 383 block.. whatever is cheaper) set up for about 500 horses.. now.. i can go with N/A power .. but would it be cheaper to bolt on a supercharger instead?? i know a guy had a thread about superchargers a few rows back but i
was curiouse if anyone has or thinks its possible to supercharge a 383..

this is all out brainstorming.. so dont hold back with questions.. just do what u think would be best for power yet keeping it on a small to mild budget.... Thanks
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Old Jan 13, 2006 | 03:20 AM
  #2  
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i'm not sure about all the specifics on this seeing as how i'm new to the corvette world myself, but i read on here a little while back that the supercharger setup alone will run u up into $4k. Now ontop of that you're lookin at labor and other what nots... I forget the whole roundoff but somehow he managed to make the final number out to be around $8k for the setup and install. I doubt that's what you're lookin for. Personally, For the same money you could probably N/A it for the same price and then drop the S/C later down the road if you want some more.
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Old Jan 13, 2006 | 05:03 AM
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Default Supercharge It!!!

Anything is possible, given enough money. However, you already have the makings for a strong supercharged engine.

You didn't mention how many miles your target-350 engine has, so I'll say that, if it's less than 30-40K miles, I'd look at using a Weiand 142-c.i. supercharger. Details of it can be found HERE. Summit racing has the kit listed for $1579 (unpolished) or $1979 (polished).

It should put you somewhere around 330 HP (at 5000 RPM), and 450 lbs.-ft of torque at 3500 RPM. That is assuming that you basically just bolt it up, and go. Of course, you dare not spin the engine past 5000- the cam is done by 5200, and with boost on top of the stock (cast) pistons, you're in marginal territory, even at 6 lbs. of boost, at 5000.

Consider this: changing your engine to a 383 SBC requires a new crankshaft, new pistons, new flywheel or flexplate, new harmonic balancer, an overbore to your block, and a significant amount of down-time... And all it gives you is 33 extra cubic inches...

Now, consider your 350, a typical SBC, that you're considering adding a supercharger on... When you put on a kit that can deliver (for example, to make the math easy), 7.35 lbs. of boost at 6000 RPM... What this means is that, instead of sucking air into the engine to get the air it needs, you're pumping in air at a rate that it could never get on it's own... The math works this way:

Your engine, at 100% efficiency, would pull in 350 Cubic inches of air every four rotations. Of course, the engine isn't 100% efficient, but we'll ignore that... Now, you're pumping in air at pressure, 7.35 lbs. OVER atmospheric, or at 22.05 lbs. absolute pressure. 22.05/14.7 = 1.5, or 150% of what the engine could EVER get on it's own... So, instead of using 350 cubic inches of air, your engine is now using (350 * 1.5) = 525 cubic inches... Essentially, you're faking out your engine to think it is far BIGGER than it really is....

Now, what is required to supercharge your engine, you ask??? Well, obviously, you'll need a taller hood, OR you must cut a hole in it... For the engine, you'll need blower pistons (~$280/set, if memory serves). Beyond that, re-use the rods, the crank, the balancer and flywheel or flexplate. I'd suggest going to a better cam... Maybe an RV cam, around 260-270 degrees of duration. If you can afford a roller cam, then I'd say to go for it...

For a performance SBC, the head you have aren't gonna' hack it... BUT, you can find some decent heads that won't break the bank... I'd look at World Products Motown 220 heads... Those heads, with a 142 mini-blower (8 lbs. Max boost, since you still want to run pump-gas, yes? ) and a roller cam???

My computer says you'll see 560 HP at 6000 RPM, and 525 lbs.-ft of torque at 5000. But the really interesting thing is that torque curve is almost flat, with >400 lbs.-ft of torque from 2000 all the way to 6500 RPM... Suppose, however, you choose to run a hydraulic flat-tappet, to save some green... You will see a HP drop of about 10%, across the board... but it will STILL make about 500 HP... be a reliable daily-driver, if that's something you would like....

My opinion is, dollar for dollar, there is NO bigger performance gain for the buck then a supercharger.

(I don't consider Nitrous systems, because I like my power to ALWAYS be available.... )
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Old Jan 13, 2006 | 05:33 AM
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If the sound of forced induction didn't drive me insane, you'd almost have me sold on a supercharger breathial!
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Old Jan 13, 2006 | 07:28 AM
  #5  
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Originally Posted by breathial
Anything is possible, given enough money. However, you already have the makings for a strong supercharged engine.

You didn't mention how many miles your target-350 engine has, so I'll say that, if it's less than 30-40K miles, I'd look at using a Weiand 142-c.i. supercharger. Details of it can be found HERE. Summit racing has the kit listed for $1579 (unpolished) or $1979 (polished).

It should put you somewhere around 330 HP (at 5000 RPM), and 450 lbs.-ft of torque at 3500 RPM. That is assuming that you basically just bolt it up, and go. Of course, you dare not spin the engine past 5000- the cam is done by 5200, and with boost on top of the stock (cast) pistons, you're in marginal territory, even at 6 lbs. of boost, at 5000.

Consider this: changing your engine to a 383 SBC requires a new crankshaft, new pistons, new flywheel or flexplate, new harmonic balancer, an overbore to your block, and a significant amount of down-time... And all it gives you is 33 extra cubic inches...

Now, consider your 350, a typical SBC, that you're considering adding a supercharger on... When you put on a kit that can deliver (for example, to make the math easy), 7.35 lbs. of boost at 6000 RPM... What this means is that, instead of sucking air into the engine to get the air it needs, you're pumping in air at a rate that it could never get on it's own... The math works this way:

Your engine, at 100% efficiency, would pull in 350 Cubic inches of air every four rotations. Of course, the engine isn't 100% efficient, but we'll ignore that... Now, you're pumping in air at pressure, 7.35 lbs. OVER atmospheric, or at 22.05 lbs. absolute pressure. 22.05/14.7 = 1.5, or 150% of what the engine could EVER get on it's own... So, instead of using 350 cubic inches of air, your engine is now using (350 * 1.5) = 525 cubic inches... Essentially, you're faking out your engine to think it is far BIGGER than it really is....

Now, what is required to supercharge your engine, you ask??? Well, obviously, you'll need a taller hood, OR you must cut a hole in it... For the engine, you'll need blower pistons (~$280/set, if memory serves). Beyond that, re-use the rods, the crank, the balancer and flywheel or flexplate. I'd suggest going to a better cam... Maybe an RV cam, around 260-270 degrees of duration. If you can afford a roller cam, then I'd say to go for it...

For a performance SBC, the head you have aren't gonna' hack it... BUT, you can find some decent heads that won't break the bank... I'd look at World Products Motown 220 heads... Those heads, with a 142 mini-blower (8 lbs. Max boost, since you still want to run pump-gas, yes? ) and a roller cam???

My computer says you'll see 560 HP at 6000 RPM, and 525 lbs.-ft of torque at 5000. But the really interesting thing is that torque curve is almost flat, with >400 lbs.-ft of torque from 2000 all the way to 6500 RPM... Suppose, however, you choose to run a hydraulic flat-tappet, to save some green... You will see a HP drop of about 10%, across the board... but it will STILL make about 500 HP... be a reliable daily-driver, if that's something you would like....

My opinion is, dollar for dollar, there is NO bigger performance gain for the buck then a supercharger.

(I don't consider Nitrous systems, because I like my power to ALWAYS be available.... )
man does my head hurt now...
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Old Jan 13, 2006 | 07:44 AM
  #6  
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some other options: look for a 400 c.i. shortblock and build a 406 or take the crank out of your 350, buy main bearing spacers and install the 350 crank in the 400 block and you have a 370 cube inch motor.

If you're thinking of forced induction, you will have to use a forged crank.
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Old Jan 13, 2006 | 11:00 AM
  #7  
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Originally Posted by breathial
Consider this: changing your engine to a 383 SBC requires a new crankshaft, new pistons, new flywheel or flexplate, new harmonic balancer, an overbore to your block, and a significant amount of down-time... And all it gives you is 33 extra cubic inches... My computer says you'll see ...
Shirley1978:
To clarify, there's more to a 383 than just 33 more cubic inches of volume. Most of those inches are gained via increased stroke ... about 84% of the increased volume from 350 to 383 is due entirely to stroke. In general, more stroke = more torque. Torque is what folks enjoy as that "seat of the pants" acceleration. A typical 383 is recognized more for its much-improved torque (foot pounds of force) than its extra cubic inches. And you won't need a computer to see it ... your butt will know it ... and your wallet will like the $ of a simple but well-planned & executed 383.

BTW, there are many INTERNALLY balanced 383 stroker cranks that DO NOT require new or use different harmonic balancer/damper or flywheel/flexplate ... new INTERNAL balance 383 cranks start at about $210. External balance cranks do require damper & flexplate different from 350 ... INTERNAL can use 350 damper & flexplate/flywheel.

If you were to rebuild your Goodwrench 350 you'd spend about: $80 grind & polish stock crank, $100-$200 new pistons, $90-$100 to resize stock 5.7" rods, $75 new cam ... that's about $400 for just those parts.

In contrast, the same new parts for an INTERNAL balance 383 are about: $210 new INTERNAL balance 383 crank, $190 new 383 pistons, $200 new 6" rods w/new bolts, $140 new small base circle cam ... about $740 to replace those 350 parts you'd have otherwise spent $400 to simply refurbish/replace. So, going to an INTERNAL balance long rod 383 would cost only about $340 more to replace w/ new those 350 parts you'd refurbish/replace.
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Old Jan 14, 2006 | 03:06 AM
  #8  
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Originally Posted by Kalway
If the sound of forced induction didn't drive me insane, you'd almost have me sold on a supercharger breathial!

Actually, I LIKE the sound.... Of course, having a 6-71 Jimmy sitting on top... So I'd better like it!
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Old Jan 14, 2006 | 10:43 AM
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This is all fine & well but IMO you can't just throw some parts on and hope for the best. There is no point in building a fine structure on a poor foundation. There is no reason that you can not go either way (383 or blower), but please,don't just throw some parts on. For these kinds of setups you need to either have your block machined or purchase a new short/long block. I see nothing wrong with using your engine as the starting point, but a good shosrt block really won't cost much more. Just don't go cheap now, you know the old TV saying "Pay me now or pay me later"
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