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View Full Version : 2 or 4 bolt main's?



twiget
09-23-01, 06:35 AM
I read somewhere that the '90-'92 LT5's had 2 bolt main caps and that one of the upgrades done for the '93-'95 LT5's was to make them 4 bolt main's.

Is this true or what?

Jason

Rob
09-23-01, 09:38 AM
Yep. It's true.

twiget
09-23-01, 10:14 AM
Thanks Rob.

Jason

ArtZR1991
09-25-01, 07:46 PM
Both have a forged steel crankshaft, and the main caps are heat fitted into a "ladder" frame lower end. When the hoesepower was increased to 405, the rpm was a bit higher (for the rating), so for liability reasons, the cap part of the ladder was changed to 4 bolts.

To my knowledge, there has never been a problem with either. Keep in mind that the endurance records set (and still held) by the ZR1 were set with a 375 hp, 2 bolt engine.

Regards,

rkreigh
11-18-01, 12:01 PM
because of the ladder design of the bottom end the 4 bolt engines probably only add about 5% strength from what I read. Probably more of a marketing than an engineering thing as all the gearhead are after "4bolt" engines.

has anyone ever converted a 2 bolt engine to a 4 bolt config???

could the 4 bolt bearing ladder be added to a 2 bolt block and the engine line honed??? can the 2 bolt ladder be drilled or modified???

I've heard of using studs instead of bolts, anyone ever hear of this being done???

tia for any tips.

Ken
11-18-01, 05:20 PM
Use a girdle. ;)

_ken :w

Ken
11-18-01, 05:48 PM
Didya think I meant "Playtex". :crazy

_ken :w

Bullitt
11-19-01, 02:05 PM
Are the main bolts straight or splayed on the LT5?

ArtZR1991
11-19-01, 03:46 PM
Straight on the LT5, and the "ladder" frame, which it has is another descriptipn of a "girdle", isn't it (I mean automotive, not women's apparel, you wise guys!)


PS, I assume everyone knows, but the prototype w12 Volkswagon broke the ZR1 records a couple weeks ago. My hat's off to them; after all, records are meant to be broken. We ZR1 folks can still feel good in having held the record for so long, and for being the only production engine to ever hold it, since WWII. The W8 was a 600 HP one off prototype, as was the car, not intended for production at anywhere near that level. The LT5, though used in an old test mule Corvette ZR1, was an off the production line engine, sent to the track instead of going into a production car. And that's the way it was when it set the records!

JT ZR-Won
11-19-01, 04:28 PM
Originally posted by ArtZR1991
PS, I assume everyone knows, but the prototype w12 Volkswagon broke the ZR1 records a couple weeks ago. My hat's off to them; after all, records are meant to be broken. We ZR1 folks can still feel good in having held the record for so long, and for being the only production engine to ever hold it, since WWII. The W8 was a 600 HP one off prototype, as was the car, not intended for production at anywhere near that level. The LT5, though used in an old test mule Corvette ZR1, was an off the production line engine, sent to the track instead of going into a production car. And that's the way it was when it set the records!

Well said Art :)

Jay