From:
doctorduke_REMOVE_307932_THIS_@yahoo.com
The Vega aluminum block is certainly weaker than a typical cast iron
block. You have to remember that though it is "high-tech", it was
originally designed for no more than about 125 HP, with no eye toward
modification for racing, so it is definitely not "overdesigned". You
can refer to the first quarter 2001 CV magazine for the article I
co-authored with Mike Hall on the development problems Cosworth had in
the early seventies. The production CV blocks are a little better
than those early blocks and the HD block much better, but once you get
up to the 9000 rev level reliabililty is suspect.
For a boosted engine running lower revs you have to take into account
cooling considerations. If you double the indicated horsepower, you
double the amount ot heat that must be removed from the engine.
Rather than using the aluminum Vega block, anyone attempting a high
boost turbocharged engine should consider the "Iron Duke" block. A
lot of racing parts were built for this engine. Cosworth might still
have some DOHC head conversions and Arias builds an aluminum version
of the block. The Iron Duke block actually had a lot more development
for racing than the Vega block, and it proved out to be a durable
foundation for a high specific output racing engine.
Being as how the Iron Duke engine was used in the '77 Astre rather
than the aluminum 140, the mounting hardware to install it in a H-body
chassis is available.
Duke
[This is message #10472 by user doctorduke on Yahoo! Group Cosworth Vegas:
http://groups.yahoo.com/group/cosworthvegas ]