Wow! This generated quite a lot of response, which was surprisingly less
bitter than I had expected from the purists. First off, many thanks to all
who offered advice (Brad Kahler, Maurice Dykes, Ken Nuelle, Dave Terrick,
Chris Kantijarev, Michael Porter, and Joe Cowan) and encouragement (all the
above and Andy Mace). I'm just going to post the stuff to the list for
everyone else's benefit.
Issue #1: Can the 2.5 be bored successfully to 2.7?
Well, everyone agrees there wouldn't be very much cylinder wall left after
this, so maybe that's not such a good idea. My logic here might have been
flawed, but I know someone who has a TR6 and had his blown engine replaced
by a Triumphtune 'bored' 2.7 liter. I was assuming that any 2.5 could be
safely bored to that displacement, as TT doesn't seem to be a hack
operation. I think I was assuming that the block for the 2.0 and 2.5 were
the same, which is probably wrong. I know the heads are the same. I'll
contact them and do more research.
Issue #2: Can the 2.0 be stroked to 2.5 liter? And what's involved in
this?
Simply, yes. The crank is incorrect and will need to have throws roughly
.75" longer than the 2.0. Additionally, the #1 & #2 (or #2 & #3) rod ends
may have clearance problems which require the oil pan to be dimpled, but no
other mods appear to be necessary.
Issue #3: What about that gearbox and rear end made of toothpicks?
Everyone (myself included) is aware of the, um...shortcomings of the GT6
gearbox and rear end. My plan is not to exceed 150 horsepower or so, no
matter what engine I end up with. It sure would be nice if a TR6
tranny/diff could be made to work, but that would appear to be a lot of
frame mods, etc. Another possibility here is to work the existing units
over and go *easy* on them. The GT6 gearbox can be beefed up and made more
reliable in a few ways, and the rear end as well, but I doubt any amount of
mods will allow them to handle 200 hp!
Issue #4: Why do you want to do this and 'ruin' an otherwise 'stock' GT6?
Because I can. It's MY car and I can screw it up how I want! ;0
Acutally, I'd just like to see more usable horsepower out of a fabulous car.
I love my GT6! I had my first one when I was 17 years old; it was my first
car ever and I've never been out of love with the things yet. Guess I'm
hooked, huh?
RESULTS: I think I'm going to buy a TR6 to satisfy my craving for
horsepower while I continue to do homework on the GT6 mods. Now if I can
just convince my wife that we don't need that 50 square feet of garage
room...
Again, thanks all for your input. More will follow. Anyone around Atlanta
have a good TR6 for sale? ;-)
Later!
Scott Decker
70 GT6+ KC79034L
Braselton (near Road Atlanta), GA
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