c5r and other 427's

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Jun 27, 2006 | 05:51 PM

wvaboy

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From: midland,nc

c5r and other 427's

couple of questions.

what is the biggest difference in a c5r and "other" ls based 427's?
why would someone pay the extra 3 grand or so for the c5r? i read everything about sleeves being cast into the newer 427's, but is the c5r that different.

i'm getting a 427 from sdpc as we speak for my t/a. what cam should i be considering? want it big, but driveable.

thanks,
rob

Jun 27, 2006 | 08:18 PM

11 Bravo

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Quote:

Originally Posted by wvaboy

I'm not sure why anyone would buy a C5R over a LS7 nowadays. Don't know the difference between the two's sleeves. I'm sure someone will chime in. My 244/250 is perfectly drivable but still has a pretty radical lope. I wouldn't go a whole lot bigger than that for a street car.

Jun 27, 2006 | 08:34 PM

Haans249

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The sleeves in the LS7 block are pressed in liners, they're not cast in. A resleeved LS2 block will be stronger then the LS7 block, but i've only heard of one instance of the LS7 block dropping a sleeve, and that was on a early production block that was horribly machined plus a 100 shot.

Jun 27, 2006 | 08:58 PM

wvaboy

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From: midland,nc

hans249

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For those that are wondering, the LS7 block is a different casting than the LS2. The differences are that the bore is larger, (4.125 finished hone), the timing chain dampener is different (larger bolt pattern), and it has 7.0 cast in the side of it. These blocks are not like resleeved blocks because the sleeves are installed during the casting process, not pressed in afterwards. From dealing with sleeved blocks in the past I would think there would be less chances of problems because of this process. I have actually seen a sleeve come out of a block (none LS) after it was cleaned in a jet washer because the water was so hot it expanded the aluminum and the sleeve fell right out. No, they are not a C5R block but they are a good piece. As for the price, Katech's post earlier is absolutely correct. This is not a mass production block like the LS2 block so the price is higher

please please, i hope i've done my homework on this one and definately don't want to start a i'm right you're wrong thing here.

11bravo thanks for some help. even though you bumped your head with that whole dallas/steeler thing i read a few days ago!

any other helpful hints appreciated.

later,
rob

Jun 27, 2006 | 09:29 PM

Steve - Race Eng

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C5R vs production blocks

C5R and LS7 blocks have pressed in gray iron sleeves and steel main bearing caps. Other LS blocks: LS1, LS6 and LS2 blocks have cast in gray iron liners and powdered metal caps.

All LS blocks except the C5R are cast from 319 alloy aluminum. The C5R is cast from 356 alloy which is the same alloy used in most aftermarket racing aluminum blocks. The 356 alloy is slightly stronger and considerably more ductile than 319 alloy.

The C5R uses very long liners (6") making them very difficult to properly hone. That length leaves only .250" of over travel to the main bearing webs.

The high price of the C5R is due to low volume production and the higher cost of the 356 alloy casting.

Steve

Quote:

Originally Posted by wvaboy

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