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Boring the block to 2700cc


aaron77

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I have a 2500TC with a stuffed head and worn big end bearings both having done 207,000km.

I have a PI head ready to be reconditioned and wish to bore out the block to 2.7L, also with a Wade 444C cam with a 285 duration (that's what I've been recommended).

Should the head still fit onto the oversize bores okay and is there anything else I should be Renewing/updating while in there? I dont mind spending the money as long as I get a decent amount of torque and a few more ponies I'm happy  ;)

Cheers

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Mazda E5 77mm pistons are the go = 2654cc

Standard they are slightly dished which helps keep the compression lower if you aren't going mad ... a flat top is available from the 1.5 twin carb model... these should be "Cheep" ... like the budgie

You will need 21mm or 22mm ( I forget which) little end bushes made for your rods to fit the metric piston gudgeon pins... find a good machine shop

S or TC head is better than PI.... more room for a big inlet valve (38mm datsun)

Special head gasket talk to Greg Tunstall... CTM  in queensland... about $70

Actually he is probably a good contact for all this stuff as he does heaps of 2.7 conversions

http://www.triumphowners.com/5

http://www.users.bigpond.com/gtmech/Home.htm



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  • 2 weeks later...

I'm intersted in the mazda piston conversion - however I'd like to do a 200cc overbore on a 2 litre to lump to get a real oversquare screamer. Can I use the same mazda pistons or can you recommend any others that would do the trick?

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That was definately worth a listen.....

I'm not dead set against a 2.5 based engine - it's what I've got in now. It's just that I know what a lovely, revvy, sweet motor the 2000 is. Inherently better crank harmonics and therefore more reliable in the (well thrashed) long run.

Am I being too harsh on the 2.5 lump?

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Depends... if you like the torque of the 2.5 and are happy with 6000 rev limit go for a 2.5.  Lighten the flywheel as much as possible... the crank is all the flywheel that engine needs (29kgs)

A tuned 2 litre has the potential to make more bhp than a 2.5 but will never make the same torque... it weighs a bit less but not much in real terms .... if you build the engine right it is good for an easy 7000+rpm ... not bad for a 1950's design. A short diff ratio and as much lightweighting as possible is the key to good 2000 performance

Try doing 7000+ rpm in a 2.5 and it will get expensive... don't believe anyone who says otherwise

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When I said lightweighting I thought you meant from a 2000 sedan... spit will be no issue.... investigate the Picton Sportcar method of engine installation... james C will enlighten you... basically move the engine back about 8 inches and use a Spitfire frontplate.

Contact Chris Witor for the piston type he used to get 2179cc... VW I think

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The engine is already in 8" back using the method you mentioned- though I don't think Picton sportscars can claim that they did it first..... The car should weigh around the same as a standard Mk III when finished - so 750 - 780kgs, a good 200kgs or so lighter than a lightened saloon I would imagine.

I will contact Chris Wittor to see if he can enlighten me on the pistons. Many thanks.

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From memory I think that Kevin Ginger's final incarnations got the motor a lot further back than that - it was practically in his lap.

I think that the main question has to be why Triumph didn't do it - they could have got the GT6 to handle properly then!

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  • 2 weeks later...

[quote by=itiejim link=Blah.pl?b=2000,m=1153176242,s=14 date=1154419519]From memory I think that Kevin Ginger's final incarnations got the motor a lot further back than that - it was practically in his lap.

I think that the main question has to be why Triumph didn't do it - they could have got the GT6 to handle properly then![/quote]

They did! GT6R engine was pulled back in the chassis (but not as much as the Ginger machine), and lowered significantly. In fact the GT6R didn't need a bonnet hump, it used a standard type Spitfire Le Mans bonnet. Remember this was late 65 before GT6 production had started proper.

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[quote by=andythompson link=Blah.pl?b=2000,m=1153176242,s=17 date=1155715287]Any pictures apart from the published Robson one without a bonnet?[/quote]

There is at least one more in the Heritage archive (the same source as Robsons) but it dosn't show the bonnet. There are several more in the same series of shots that didn't make it into the Triumph archive (subsequently deposited with Heritage) from the  'official' Triumph photographer. They show a bonnet next to the car but not fitted.

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