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Old 01-25-2008, 08:11 AM
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HP limit for 400 Chevy 4-bolt main??

Hey guys,

Just wondering if anyone has a good idea of how much a stock block SBC 400, punched .030, can take. I have a solid rotating assembly, so that's not an issue.

Reason I'm asking is I've added a vortech supercharger to my setup. Engine Analyzer says 690 HP at 6000 RPM, about 8psi boost on 9.9:1 SCR. I am planning on a conservative tune using water/alky injection to ensure no detonation, plus boost retard via the Mallory MAP sensor.

The block is a four bolt main, stock main caps, stock bolts, etc.

A friend of mine was talking to a auto machinist, and the machinist thought it was gonna split the block down the lifter valley.

Any thoughts? I really don't have $3K for a Dart block either.

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Old 01-25-2008, 08:26 AM
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As far as 400 SBC's go I think that the 4 bolt was the weaker of the options because GM removed a lot of casting material to compensate for weight, which they figured out was a bad idea and just went back to the 2 bolt setup, after only a few (or maybe just one) year(s).

If I were you I would spring for some main stud girdles, as well as the lifter valley girdles that they design for SBF motors that have a tendancy to split down the middle.

Even if it only costs a couple hundred more bucks, it will be worth the effort.

Or if you haven't had machining done just find a 2 bolt casting and still get the stud girdles to calm your nerves when you stand on it.

690 HP huh?

What tires are you going with? I want to purchase some stocks in that company!!!
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Old 01-25-2008, 08:36 AM
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Quote:
Originally Posted by hotrodf1
Hey guys,

Just wondering if anyone has a good idea of how much a stock block SBC 400, punched .030, can take. I have a solid rotating assembly, so that's not an issue.

Reason I'm asking is I've added a vortech supercharger to my setup. Engine Analyzer says 690 HP at 6000 RPM, about 8psi boost on 9.9:1 SCR. I am planning on a conservative tune using water/alky injection to ensure no detonation, plus boost retard via the Mallory MAP sensor.

The block is a four bolt main, stock main caps, stock bolts, etc.

A friend of mine was talking to a auto machinist, and the machinist thought it was gonna split the block down the lifter valley.

Any thoughts? I really don't have $3K for a Dart block either.


You really, really, really need a Dart block. You have to stop and think, you are working with 30+ year old cast iron that was never designed to do what you want. I have pulled to mains with webbing included from a few 400 blocks (still holding onto the crank) and these were not near 690 HP. If you do build it, just remember, you just lit the fuse on a high dollar bomb. Hope this helps
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Old 01-25-2008, 08:59 AM
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Quote:
Originally Posted by Double_v23
As far as 400 SBC's go I think that the 4 bolt was the weaker of the options because GM removed a lot of casting material to compensate for weight, which they figured out was a bad idea and just went back to the 2 bolt setup, after only a few (or maybe just one) year(s).

If I were you I would spring for some main stud girdles, as well as the lifter valley girdles that they design for SBF motors that have a tendancy to split down the middle.

Even if it only costs a couple hundred more bucks, it will be worth the effort.

Or if you haven't had machining done just find a 2 bolt casting and still get the stud girdles to calm your nerves when you stand on it.

690 HP huh?

What tires are you going with? I want to purchase some stocks in that company!!!
Up in the air on tires, the last ones lasted about 3K miles. M/T ET Street Radials. Probably do them again, they seem to be the best choice for what I do with the car.

Hmmm. I guess I hadn't thought the block would be that much of a problem.

This isn't good. Now I've got a blower setup on a running motor that I'm scared of. I've already driven it around without the water injection, with LOTS of boost retard and it sure is fun.

Maybe I could find a block used or something from a guy changing over to a big block.
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Old 01-25-2008, 09:00 AM
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Search the Chevy section of turbomustangs.com. There's quite a bit of discussion of this subject on there. I think with a partial fill you should be ok to 700hp if you keep the rpms down. Most guys say the two bolts are stronger. From discussions on there it seems a two bolt with a partial fill and sub 7000 rpm is good to 1000. I have a 362 assembly I've been thinking about putting in a 400 block I have with a turbo. Worst case is it blows up.

Kevin
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Old 01-25-2008, 09:11 AM
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Quote:
Originally Posted by KA67_72
Search the Chevy section of turbomustangs.com. There's quite a bit of discussion of this subject on there. I think with a partial fill you should be ok to 700hp if you keep the rpms down. Most guys say the two bolts are stronger. From discussions on there it seems a two bolt with a partial fill and sub 7000 rpm is good to 1000. I have a 362 assembly I've been thinking about putting in a 400 block I have with a turbo. Worst case is it blows up.

Kevin
I looked in Turbomustangs but I guess I wasn't in the right area. Ill try again.

I know, I just don't want to kill a good rotating assembly. If I thought I could catch it in time, by some other symptom, I would just lock and load. But I don't really like catastrophic failure. Not a big fan. Then I'll need a block and a rotating assembly.
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Old 01-25-2008, 09:11 AM
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I have seen some pretty good deals on racingjunk.com quite a few people selling that kind of stuff.

It is not like you have to put the boots to it every time you drive it, but if you want to get full potential from your setup then you will need to strengthen the block.

In all actuality you ae probably using at most 60% of your power crusin on the streets, as long as you don't wind it up it might last a long time....but there will always come a point when you want to really mash it and then it is a guessing game.

It is not like you are bouncing pistons around in a block made of glass, it will take some abuse, but what you are asking is probably too much.
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Old 01-25-2008, 09:18 AM
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The 400 block with the big cylinders and large main line equals weak main webbing as there where we have seen issues with 400 blocks along with there very weak decks and cylinders and with that much power pulling the thread out of the head bolt holes may also be a problem.

Studs don't make the main caps any stronger as there still just grey cast iron caps with better hardware and filling a block doesn't do anything to strenthen the deck and the top of the cylinders.

A good Dart block all machined out should run about 2395.00 and would stand up fine for what you are doing.

Here is a pic of a 400 block where the guy was not making 700 horse but here are the results.

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Old 01-25-2008, 12:25 PM
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255-265 horsepower according to
http://www.montecarloss.com/SSThunder/SBCinfo.html
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Old 01-25-2008, 01:23 PM
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Originally Posted by CNC BLOCKS N/E
The 400 block with the big cylinders and large main line equals weak main webbing as there where we have seen issues with 400 blocks along with there very weak decks and cylinders and with that much power pulling the thread out of the head bolt holes may also be a problem.

Studs don't make the main caps any stronger as there still just grey cast iron caps with better hardware and filling a block doesn't do anything to strenthen the deck and the top of the cylinders.

A good Dart block all machined out should run about 2395.00 and would stand up fine for what you are doing.

Here is a pic of a 400 block where the guy was not making 700 horse but here are the results.


Exactly what I was talking about......
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Old 01-25-2008, 01:25 PM
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Quote:
Originally Posted by dawg
That appears to be just what the motor was rated at in that combo in that vehicle.

I have been driving the car making close to 500 HP for a couple years now. No problems . . .. yet.
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Old 01-25-2008, 01:28 PM
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Quote:
Originally Posted by CNC BLOCKS N/E
The 400 block with the big cylinders and large main line equals weak main webbing as there where we have seen issues with 400 blocks along with there very weak decks and cylinders and with that much power pulling the thread out of the head bolt holes may also be a problem.

Studs don't make the main caps any stronger as there still just grey cast iron caps with better hardware and filling a block doesn't do anything to strenthen the deck and the top of the cylinders.

A good Dart block all machined out should run about 2395.00 and would stand up fine for what you are doing.

Here is a pic of a 400 block where the guy was not making 700 horse but here are the results.

Okay, i hear ya. That's what I need for piece of mind. I was thinking the same about the block fill and girdles. Doesn't seem like it would get me to the promise land anyway.

Is the block I have worth anything? Like $500??? For someone doing NA I would think it would be fine. Probably would just take a good honing and be ready to go.
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Old 01-25-2008, 02:05 PM
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Originally Posted by hotrodf1
That appears to be just what the motor was rated at in that combo in that vehicle.

I have been driving the car making close to 500 HP for a couple years now. No problems . . .. yet.
Boy I wish I could base all my info on one block that has worked for me for 5 years but I can't as we deal with a couple hundred blocks a year and about 500 phone calls and emails and problem blocks.
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Old 01-25-2008, 02:37 PM
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Here is a little blurb taken from that montecarloss site. I was reading along and found this way at the bottom. Just hadn't gotten that far until later.

"2-bolt blocks with OEM main bolts are good to 400hp
2-bolt blocks with ARP main studs are good to 550hp ++High Nickel Blocks to 700hp
4-bolt blocks with OEM main bolts are good to 475hp
4-bolt blocks with ARP main studs are good to 700hp
OEM Blocks with Splayed 4-bolt main studs are good to over 950hp
Bowtie blocks with splayed 4-bolts main studs should handle over 1500+hp! "


I guess I probably need to face the music on this one and build with a different block before I really do some damage.
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Old 01-25-2008, 05:01 PM
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Quote:
Originally Posted by hotrodf1
Here is a little blurb taken from that montecarloss site. I was reading along and found this way at the bottom. Just hadn't gotten that far until later.

"2-bolt blocks with OEM main bolts are good to 400hp
2-bolt blocks with ARP main studs are good to 550hp ++High Nickel Blocks to 700hp
4-bolt blocks with OEM main bolts are good to 475hp
4-bolt blocks with ARP main studs are good to 700hp
OEM Blocks with Splayed 4-bolt main studs are good to over 950hp
Bowtie blocks with splayed 4-bolts main studs should handle over 1500+hp! "


I guess I probably need to face the music on this one and build with a different block before I really do some damage.

Where in the hell did you come up with this info. as I do this type of work every day and I find your post not very factual.

Adding main studs to a set of 2 bolt caps does not make the caps any stronger as they are just a grey cast iron and will break and 010/020 two bolt block with studs is good for 700 horse NOT LIKELY.

Hell we rate our best 350 block at 600 horse.


Dart rates there nodular iron block at only 900 and it has beefy decks, webbing and thick cylinders and bulk heads fornt and rear on there blocks and a stock block with just splayed caps is better then a Dart block.

Here is a pic of a two bolt block that made 425 horse and it did have studs and the customer pulled it down because the oil pressure was dropping and after we installed splayed caps and the customer installed all the same parts in the block after they turned the crank it has run for the last 3 years with no more problems.

And this guy listen to some like you who does not do this type of work for a living and gives ill advise cost this guy alot of money to build the engine twice.


It really hard to believe you are an engineer and thinking studs makes cast iron caps stronger as thats like putting ARP rod bolts in an old set of rods does not make the rods any stronger they just have better hardware they are still old rods.

I am sure Dick Maskin from Dart would like to meet you and you should also meet with the GN engineers that have designed the OEM blocks and let them know about you theorys. Look in the Chevy catalog and see what GM rates there blocks at.

You must be realated to F-BIRD-88

Just when I think I have seen it all.

Go over this link if you have time.
http://www.chevelles.com/forums/showthread.php?t=38173
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