273 Supercharged...ITS HAPPENING PEOPLE!!

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Hey Baker, were ya been? It's been like... A month!

Bakerlite said:
Buying new rods, but not changing the pistons?? Then not balancing an assembly that has different rods and will need to make decent RPMs to make any boost/power???
Your making a bunch of poor decisions here...
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Oh hell yea... AGREE!

Bakerlite said:
When's the last time you found an Eagle forged rod to fit a 273 that were the same weight as a factory rod?, not to mention he's talking about swapping out cranks...The rods are overkill...
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Maybe so, but the OE rods are no hero size units ether. So I guess I'm leaning along with him. Unless he's building a super charge 273 for mileage, ha ha ha ha....
 
Bakerlite said:
Buying new rods, but not changing the pistons?? Then not balancing an assembly that has different rods and will need to make decent RPMs to make any boost/power???
Your making a bunch of poor decisions here...
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Not sure I understand what your saying. It will have new rods and new Pistons. I fully plan to weigh the new assembly vs the old. If it's over 10 grams different I will balance. Once again though this is not a race engine. What would you consider "decent rpms"? I am working with Hughes on the correct cam and will tune the blower for the rpm I plan to hit.
 
Chrissock you will be surprised as to weight differences between using eagle rods vs std. It will be more than 10g difference.With my 318 the differnce between std piston,pins rod vs hypers pistons pins ,scat rods was 2.5 kilo ,thats 5+ lbs. I know your using cast pistons but.... for a few hundred its like insurance smoother idling , less harmonics, ...
 
Well I have some information to share. First thanks for all the interest. I know we haven't made great progress yet so it not exciting but I promise it's coming. Should have the block and parts back next week to start assembling the bottom end. As long as I can find a crank!! Still looking for a forged crank so that might hold us up a bit. The assembly WILL BE BALANCED. I was able to "negotiate" the price down to a point where it makes sense and we decided to just do it. Cometic is making a set of head gaskets that are the correct bore and are set up for the boost. They are not cheap but I didn't want to skimp on that. I wasn't aware they offered that service but it's good info for anyone doing weird bore sizes. I am getting anxious to start getting this thing together. I have so much to do!! Don't want to rush the machine work though. Stay tuned!!!
 
chrissock said:
Well I have some information to share. First thanks for all the interest. I know we haven't made great progress yet so it not exciting but I promise it's coming. Should have the block and parts back next week to start assembling the bottom end. As long as I can find a crank!! Still looking for a forged crank so that might hold us up a bit. The assembly WILL BE BALANCED. I was able to "negotiate" the price down to a point where it makes sense and we decided to just do it. Cometic is making a set of head gaskets that are the correct bore and are set up for the boost. They are not cheap but I didn't want to skimp on that. I wasn't aware they offered that service but it's good info for anyone doing weird bore sizes. I am getting anxious to start getting this thing together. I have so much to do!! Don't want to rush the machine work though. Stay tuned!!!
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You probably already know this, but here's some info on the crank just in case. All 68-72 340 cranks were forged. 73 340 cranks were not forged, but were shot peened for extra strength- not quite as strong as forged, but stronger than cast. Also, the 273 cranks were supposedly forged 64-66. There were also some 318s that came in trucks with forged cranks.
The way to tell by looking, besides knowing the casting numbers (which I do not) is to look at the casting or forging flash on the throws. On a cast crank, the casting flash is 1/4" wide; forged cranks have a 3/8" to 1/2" flash on the throws.
It might be hard to find an original forged crank, but you should be able to find an aftermarket forged 340 crank pretty easily. They have them at Summit, Jegs, Mancini, ebay, etc. for around $750.
 
64physhy said:
... Also, the 273 cranks were supposedly forged 64-66. There were also some 318s that came in trucks with forged cranks.
The way to tell by looking, besides knowing the casting numbers (which I do not) is to look at the casting or forging flash on the throws. On a cast crank, the casting flash is 1/4" wide; forged cranks have a 3/8" to 1/2" flash on the throws...
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273 cranks were all forged, from 1964 through 1967, from what I have seen.
 
66fs said:
273 cranks were all forged, from 1964 through 1967, from what I have seen.
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Well, there you have it. So finding a crank shouldn't be hard at all, even if you need to buy the whole engine to get it.

I have seen some claims that the 273 forged cranks aren't as strong as a forged 340 crank, but that's probably just internet BS. I would think it would still be strong enough.
 
64physhy said:
You probably already know this, but here's some info on the crank just in case. All 68-72 340 cranks were forged. 73 340 cranks were not forged, but were shot peened for extra strength- not quite as strong as forged, but stronger than cast. Also, the 273 cranks were supposedly forged 64-66. There were also some 318s that came in trucks with forged cranks.
The way to tell by looking, besides knowing the casting numbers (which I do not) is to look at the casting or forging flash on the throws. On a cast crank, the casting flash is 1/4" wide; forged cranks have a 3/8" to 1/2" flash on the throws.
It might be hard to find an original forged crank, but you should be able to find an aftermarket forged 340 crank pretty easily. They have them at Summit, Jegs, Mancini, ebay, etc. for around $750.
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This is good info to have. I am working with Herbs Mopar parts to locate a crank. So far no luck. Hopefully he can come up with something. Don't want to shell out another 750ish for an aftermarket crank.
 
VERY special thanks to Herbs Parts!! they came up with a good forged crank that was in great shape for a very reasonable price. I drove up today to pick it up and ended up chatting for an hour and a half! They are great group of people and very passionate about all things Mopar! After i picked up the crank I drove it straight back down to the machine shop to get the ball rolling on the balance and polish and surprise surprise.....More headaches. So the cast pistons that are available from speed pro are number one super expensive ($400) and number two are only made in a press wrist pin. So the upgraded rods that are available are only made for a floating pin. :banghead: So at this point its either go back to stock rods and cast pistons OR get pistons made. He believes he has a company that can do them for about $700 so I decided at this point another $300 for a forged piston is worth it. And because of the upgrade in piston we upgraded the Rods to a scat rod with a 7/16 arp bolt.

At this point the only thing holding me back from more boost is the head flow. We should be through the headaches in the bottom end at least. My wallet is getting light for sure. Ive sold some stuff to make some extra cash. I am getting alot of local buzz for people wanting to see how it does when its done. Hopefully at the new year I can start actually assembling stuff. Very interested to see how this thing works.
 
if it helps you out at all, you can skip on buying me a Christmass present this year, and put that money towards the build
 
are your stock rods and pistons floating? I think all 273s are, so replacement pistons would be, who said the speed pro are pressed only. and with a blower I would not worry about flow on the intake side, use the performer intake-very close in flow to a stock 340. run a cam with 10* more exhaust flow, and 1 5/8 - 1 3/4 headers
 
Marcohotrod said:
are your stock rods and pistons floating? I think all 273s are, so replacement pistons would be, who said the speed pro are pressed only. and with a blower I would not worry about flow on the intake side, use the performer intake-very close in flow to a stock 340. run a cam with 10* more exhaust flow, and 1 5/8 - 1 3/4 headers
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All 273's are floating pins with bushed rods. I've never seen replacement 273 Pistons in pressed pin only.
 
A blown 273 huh? Oughtta make about as much power as a hot N/A 360.
 
Build a 360 and tell everybody it is a 273. 99% of people will not know the difference. I ran 6.40's in the 1/8 with a stock cast crank 360 at 3450 lbs. Factory cast cranks are pretty strong.
 
So since the last I have posted things have been moving along slowly. Until I have all the numbers and measurements in front of me I will just say we are boring the block (after sonic test) and using Chevy 305 Rings. Still custom piston. Going to roller cam and lifters, possibly rockers. All progress had to halt until we worked out the bore size. Custom rings would have been another insane expense, Although at this point its all silly anyway.
We had a conversation about staying with the super charger. Its the easiest to do but I have been researching the down sides. The whole point of this build is to build an engine that is fun on the street. So power really high in the RPM range 3500-6000 and a small CI engine i'm afraid it would feel like an import. So the thought is that I can purchase the stuff to do a twin turbo set up for the same cost. just have to add the time to construct. In the end a pair of 58mm Comp turbos would spool quick and bring the power back down to the 1500-5000 range. So thats the way Im leaning. Probably going to use regular manifolds and just run two pipes up to the front to mount the turbos. long way to go still. Transmission and engine parts should be back in a few weeks. Then the fun can begin.
 
RustyRatRod said:
A blown 273 huh? Oughtta make about as much power as a hot N/A 360.
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THIS

You have to rev the piss out of a centrifugal supercharger to make boost

5psi will not make 400whp unless it has 11:1 compression in a small block application

My stock short block 5.0 fox made 350whp/400torq with 8psi (170cc heads,70mm TB, full exhaust)

recon the stock rods, buy replacement hyper pistons, stock crank, mill the decks, port the heads or get better heads, single plane intake, good fuel system, 1 3/4" headers, 3" exhaust, and forget about the car being a sleeper.. EVERYONE will hear you coming..
 
Quote:
Originally Posted by RustyRatRod
A blown 273 huh? Oughtta make about as much power as a hot N/A 360.

chrissock said:
Dont care.
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Head on Sir !!! Stay the course !!!!
Myself & more than a few of My psychotic Gearhead Buds are subscribed to
Your build thread . Hell & Damn we even got a 'pool' going ...

Details as You update Sir !!!!
 
mech1nxh said:
Quote:
Originally Posted by RustyRatRod
A blown 273 huh? Oughtta make about as much power as a hot N/A 360.



Head on Sir !!! Stay the course !!!!
Myself & more than a few of My psychotic Gearhead Buds are subscribed to
Your build thread . Hell & Damn we even got a 'pool' going ...

Details as You update Sir !!!!
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That's awsome!! I kinda needed this actually. It's been slow going due to getting all the custom parts and pieces in. The engine should be ready to start assembly in a few weeks. I've changed corse just a tad. I'm going to do a twin turbo set up. Still fiddling with the sizes of the twins but thinking two 58mm's. I will have to do some fab work but ultimately I think the car will be more fun in the low rpm range with a set of small snails. Also they will eat less HP.

Thanks to all who are following. I'm excited to get the parts and pieces and start getting this thing together.
 
Don't get too discouraged. Your pace is kicking my paces *** by light years..
 
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