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TR4/4A 92mm bore engine pros and cons

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Bremer

Bremer

Jedi Hopeful
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Most people seem to discourage the use of the 92mm pistons and liners due to the difficulty and accuracy required to machine the block. However, inquiring minds need to know if there are any board members here that could share first hand experience of such an engine build. Was it difficult (i.e. expensive) to get the machine work done? If yes, what were the issues? Which pistons and liners did you use? Are there any effects that diminish usability for a road car (leaks, overheating, others)? What other modifications have you done to support the larger displacement, and finally how does the engine feel?

Thanks! :encouragement:
 
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I chose a smaller bore so no experience to offer -- but my concern was heat. But then I live & drive in the desert so I am always wary of the effect of any mod on cooling.
 
Sorry i can't help you out with this, as I have no experience with using 92mm liners. However, unless you're going all out racing , it seems to me that the expenses involved would not gain you enough to warrant the extra work.

Here's a breakdown of the available liner bores that I know to be commercially available...displacements based on 92mm stroke.

83mm = 1991cc
86mm = 2138cc
87mm = 2188cc
89mm = 2289cc * largest available without extra block work
92mm = 2446cc
 
I;ve been doing quite a few 89mm's for vintage racing and been looking into doing a 92mm as an option and the only major hurdle would be a head gasket. Cometic can make a shim gasket ( I like them). It would take some effort, to make them a pattern to work from. Liners and pistons are not a problem as I have those custom made anyway. Boring the lower block should'nt be too much of a problem and the cooling is always an issue for #4 if the nessary precations/mods are not taken.
my 2 cents
Tony
 
Tony,
The Gasket Works can provide solid copper gaskets in pretty much any thickness you require. Using one probably requires a fire ring.
Also, 92mm pistons and liners are available from Cambridge Motorsports (although they don't claim that they are matching pairs).
Who does your pistons and liners? Any opinion on the above mentioned parts?

Thanks.
 
Bremer said:
Tony,
The Gasket Works can provide solid copper gaskets in pretty much any thickness you require. Using one probably requires a fire ring.
Also, 92mm pistons and liners are available from Cambridge Motorsports (although they don't claim that they are matching pairs).
Who does your pistons and liners? Any opinion on the above mentioned parts?

Thanks.
Click to expand...

Most of the Cambridge stuff is probably parts being sourced out of the US anyway. LA Sleeve makes the liners and I'd call JE / Wiseco / or Venolia about the pistons.

Don't know anyone running 92s, but be aware you might have to go with some sort of dish design to keep compression within the reach of pump gas. A benefit of larger displacement (other than the obvious) is you can run a wilder camshaft and it will be 'more streetable'. Sometimes you might have to jet it leaner since there is more pull on the carburetor.
 
I have used the copper gaskets, but I have had more reliability with the steel shim gasket sourced from Europe. As for the Sleeves, I was having Quality control issues with the regular suppliers, so I went My own way. The buy Product of the reliability is more HP and Torque but the back side of this coin is the expence! It's very hard to have one without the other. As I said, these are full race engines.
 
Thanks for the information Bob.
 
Thanks for the info Tony.
 
While there can be no real substute for cubic inches, there is a point where the loss
of reliability becomes hard to deal with.A properly prepared 87 mm engine can make over 150 hp
at 9.0 to 1 comp. Is more Better?? maybe,unless your first mate gets wind of the $$$.
Never show her a Carrillo rod and ask her to wright the check......
MD(mad dog)
 
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