Group A conrods

ppyvabw · Post by **ppyvabw** » Mon Mar 23, 2009 7:02 pm

Have finally decided what route im gonna be taking with my new engine. I'm simply sticking with 3.9 just to be realistic about costs. I was thinking about stroking the engine, but decided against it.

Just won a set of group A rods on fleabay so will be using these with 3.9 crank and pistons. How much hammer will these take?

David Hardcastle reckons 6r4 clubman engines were good for sustained operation at 7000+rpm

Are they trust worthy enough to use forged pistons? I'd like some forged pistons but I didn't want to entrust them to standard rods. Will standard cast pistons take at least as much abuse as the rods to make it worth my while having bought them, shall I just go for a set of casts?

It's going to be normally aspirated, no nitrous or anything, just lots of cam and head work...frequent bursts upto 7k etc....

topcatcustom · Post by **topcatcustom** » Mon Mar 23, 2009 9:18 pm

I always thought it was the pistons that were the weak spot- not the rods- maybe thats just the case on blown engines though.

ppyvabw · Post by **ppyvabw** » Mon Mar 23, 2009 9:32 pm

David Hardcastle reckons not to rev with standard rods above 6500. Don't know the truth in all these figures and opinions but I have got these rods now and they cost less than it would to have a standard set recircled and so on, and they were advertised as having little use.

Boosted LS1 · Post by **Boosted LS1** » Mon Mar 23, 2009 11:54 pm

Out of interest, how are you sure you have bought group A rods?

ppyvabw · Post by **ppyvabw** » Tue Mar 24, 2009 2:09 am

Worry me why don't you

Well I don't yet because they have not been delivered but the guy's got good feedback on fleabay and after the auction ended I got his address to post him a cheque and he runs an engineering firm that works with Metro 6r4's. A guy called Ian Rowlance. Such is the risk you take with stuff on ebay.

When I get them I'll weigh them and compare them with the standard ones. Group A rods are 20/30 grams or so heavier.

ian.stewart · Post by **ian.stewart** » Tue Mar 24, 2009 5:27 am

I have run HRC rods with ARP bolts above 8k, by accident, and regularly to 7, nothing special except omega pistons.

Boosted LS1 · Post by **Boosted LS1** » Tue Mar 24, 2009 9:15 am

ppyvabw wrote:Worry me why don't you

When I get them I'll weigh them and compare them with the standard ones. Group A rods are 20/30 grams or so heavier.

That's what I was hoping you'd say

I've heard they're heavier to.

ppyvabw · Post by **ppyvabw** » Tue Mar 24, 2009 11:22 am

Boosted LS1 wrote: That's what I was hoping you'd say I've heard they're heavier to.

hehehe, you old hands testing us young-uns. Like it!!

chodjinn · Post by **chodjinn** » Wed Mar 25, 2009 1:00 pm

Boosted LS1 wrote:
ppyvabw wrote:Worry me why don't you

When I get them I'll weigh them and compare them with the standard ones. Group A rods are 20/30 grams or so heavier.
That's what I was hoping you'd say I've heard they're heavier to.

I have a set of Group A rods as well, when you get them let me know how much they weigh and I can compare to mine. I bought mine from a reliable source but you got a bargain in those off ebay. Last set I saw were £250.

I'll be running mine with forged pistons and hopefully and upgraded crank.

ppyvabw · Post by **ppyvabw** » Thu Mar 26, 2009 12:58 am

chodjinn wrote: I'll be running mine with forged pistons and hopefully and upgraded crank.

Yeah I vaguely remember reading somewhere that you had some group A rods, but couldn't find the thread. I quickly glanced at your turbo uber-build thread but couldn't find any mention about group A conrods, only rockers. I thought you were only running a standard crank?

Yeah, reality hit me and I decided there was no way I could afford the ambitious mods I wanted to make

, so am going for something more realistic and moderate. Got a late 3.9 block on ebay with cross bolt bosses (undrilled) but has non cross bolt caps so I want to try and either find some caps, or have some billet ones made. (I know a guy, so I can get mate's rates)

Still got to decide on pistons though.

Did there used to be cast Omega's available from John Eales for the 3.9? Are they still available?

chodjinn · Post by **chodjinn** » Thu Mar 26, 2009 8:44 am

If you are keeping it naturally aspirated I'd recommend speaking to Sir John of Eales for pistons. I knwo Dimitri got some old stock Group A forged cosworth ones for a lot less than 'new' forged ones.

Yes currently I have a standard crank (in the engine that's in my car) but I have been offered a Group A crank as well, but for the money I could buy a stock one and modify it to the same spec. All they had were radiussed oilways and were nitrided/tuftrided.

Wotland · Post by **Wotland** » Thu Mar 26, 2009 11:40 am

Yes I bought S/H Cosworth Group A forged pistons at J. Eales last year.
Cosworth doesn't produce them any more. And I can say it was certainly the last set available in UK.