Let's say someone just bought a TR6 with rust-free chasiss, straight bodywork, and clean interior ... but a non-running engine (looks like a dropped valve).
Would you rebuild the stock engine, or swap for something more interesting? If you'd swap, what would you recommend?
Asking for a friend ;)
How about a 325ish HP british supercharged inline 6?
I'm a huge fan of small-capacity, twin-cam engines. A light, compact, 16v 4-banger is always the way to go in my book.
My first instinct is Honda F20C. Looks like you can buy a complete engine/trans with wiring harness and ECU for around $4k. Could even fit the stock digital dash cluster to complete the transformation. Perhaps too much power for the wet-noodle Triumph chassis?
Mazda Miata drivetrain might not be a bad choice. Considering the stock US-spec TR6 only puts out something like 75-80 hp at the wheels, even a stock 1.6L Miata engine wouldn't be out of place.
The G13B engine from the Suzuki Swift GTi has been swapped into Sprigets. That's about as small and light as it gets. Only 100 hp, but 7.5k redline. Should mount to the 5-speed from a Geo Tracker for RWD applications.
Since I've been racing a Mercedes 190E 2.3-16 for the last few years, I've got enough spares to put together a Cosworth engine. Prices to rebuild an engine and trans will be high. And I'll need carbs or ITBs since the original runs on CIS/KJet ... and I'm not going there!
Finally, as a former BMW E30 nerd, my thoughts go to the M20. I can get them dirt cheap. Close in spirit to the stock Triumph engine, but considerably more power and torque.
The Triumph 2.5 engine weighs about 450lbs and makes a staggering 124hp. It is a counterflow head design and has a big old anvil shaped counterweight in the center of the crankshaft that limits the motor to just over 4000rpm.
That being said it sounds FANTASTIC. Really great noises and it has enough grunt to move the flexy body on frame chassis well enough to experience some pretty unsettling cowl shake 
Pretty much any other motor you can think of will take weight off the nose and make more power.
I am a big fan of inline six motors and it is a long engine bay so I say BMW M50/52 with cams and whatever other bits help them make real power. Keep the BMW transmission to rid yourself of the 4 speed plus electric overdrive unit.
Drove a friends stripped out TR6 at an autocross for the first time the other month. Now, it has to be said, the motor is pretty built and is megasquirted.
http://www.terrykrebsphotography.com/Autocross-Pictures/i-wW7JJnJ/A
it was held back more by rear suspension than it was by the engine...
Joe S. can tell you much more on it than I can.
Torque for days.
I would probably rebuild the existing engine, but I don't live far from GoodParts, so...
Otherwise, I'd go with a LS or SBF. (Relatively) simple and cheap. http://www.britishv8.org/
124 hp? 4000 rpm? With some effort an cash you can push 180 and 6000 with mostly stock components and have a car that is an absolute blast to drive. BTDT.
Marty
The sound, feel, and overall character are more important to me in a fun street toy than any performance measure...And I loved the sound, feel, and character of my dad's mostly stock TR6. Considering that substantially more powerful engines should also have a bigger heavier transmission, a bigger heavier differential, bigger heavier brakes, and all of the associated costs and complexity/time/effort of doing so, combined with the fact that collector values on these cars are going up...I'd just do a nice street-performance rebuild on the original engine.
But if looking for a 'project' to take it up a notch and make it unique regardless of the financial or time/effort ROI for 'just' a moderate performance gain, a BMW M5x, Nissan RB25, or maybe even Volvo 'white block' I6 would certainly be interesting. And if looking for a major project to make into something completely ridiculous that simply looks like a TR6, yeah some type of V8 or boosted I6 would certainly fit the bill.
Apexcarver wrote: Drove a friends stripped out TR6 at an autocross for the first time the other month. Now, it has to be said, the motor is pretty built and is megasquirted. http://www.terrykrebsphotography.com/Autocross-Pictures/i-wW7JJnJ/A it was held back more by rear suspension than it was by the engine... Joe S. can tell you much more on it than I can. Torque for days.
You rang?
An S2000 motor is no doubt a screamer. It has loads of horsepower with a peak torque of 155 lb/ft @ 7500 RPM. A stock US-spec TR6 motor has peak torque of 143 lb/ft @ 3000 RPM. So it may not rev past 6000 without a forged crank and doubling the number of flywheel bolts, but it will move the car fairly well. I doubt the F20C would be too much power for the chassis, but it would significantly change the character of the car.
If it were me, I'd stay with an inline 6. A V8 will fit, but the width and height are tight. The BMW E46 (M54B30) engines can be had for fairly cheap and are aluminum, so not too heavy. The length will be the biggest fitment issue. I simply added an ATI damper and trigger wheel to a stock motor and had clearance issues with the steering rack. Worst case, you'd need to notch the battery tray and move the battery to the trunk. The frame has a crossmember under the front of the sump that may foul a stock oil pan. Swapping to fuel injection entails some extra work as well.
I can understand not wanting to spend piles of cash on making the stock motor produce more power. It can be done, but will not be as powerful nor long lived as a more modern engine.
This is just a weekend fun car. Maybe the occasional informal track day. I've already got a dedicated racecar and a pair of reliable/boring daily drivers for me and my wife.
So, it's all about fun.
Rebuilding the stock engine might be reasonable. They look good and sound good. No real reason to swap, except to be cool.
Either one of the in line Volvo 5 or 6 cylinder engines or the BMW straight 6 would make an interesting project - a lot more interesting, not to mention better sounding than the usual V8 options. Need some work to the rear suspension and drive shafts though.
Other way (doesn't sound as good) would be modern high output 4 cylinder - Ecoboost, Ecotec etc. Drop 100 lbs, while gaining 200 bhp.
I spent a fair amount of time behind the wheel of a tr250 this weekend and my favorite part was the soundtrack that the 6 generated.
The rest of the car wasn't something I would be interested in but the noise was glorious.
13B
13bT
NA powered Nissan RB20-something
NA JZ engine variety same formula as above
some jag I6 that isn't the length of the spaceshuttle.
suzuki/mazda kei car 3 cly turbo 660cc?
If you are seriously considering a swap, I wouldn't bother with the boat anchor that's in there.
Since there is no budget or limitation for this question, I'm going to go with a bunch of wild swap ideas that I think are cool.
1 - Saab engine connected to GM 4 cylinder transmission (S10 or Solstice)
2 - Ecotec engine connected to same GM transmission
3 - 2.5 Duratec engine out of a Ranger with a Cosworth head for 8K rpm power
4 - RB20DET from your favorite JDM engine provider (to keep the 6 cylinder sound)
5 - Volvo white block with volvo transmission (the transmission might be hard to come by)
I would keep the stock engine, although possibly with webers or fuel injection or maybe a supercharger. I would say those are a car that I'm a bit disappointed when I see one and it has an ls swap (always with the Corvette engine trim) or some other modern engine.
For a fun weekend car, keep the stock inline 6. Shave the head a bit, throw in a slightly hotter cam, rebuild the carbs and ignition system (Pertronix) and go. You can get enough power out of the stock mill to have the car be fun, and you can't beat the sound. They are also pretty darn reliable as long as you drive them regularly, and don't overbuild the engine looking for high hp.
Or you could completely re-engineer the entire car--- including rear end, suspension, brakes, cooling system and all electrics. If you go this route you may end up with a fun car........or you may have an incomplete project sitting in your garage 10 years from now. In either case, the car will be worth less than a stock TR6.
Sometimes more power isn't always the answer. The TR6 has a notoriously flexy chassis---- adding much more power would entail adding more bracing. Also the rear end is suspect even with the stock engine. Add lots of power and you'll run into more problems to solve.
My TR6 is lightly modified and runs like a champ. No, it's not fast, but it's plenty quick enough to be fun. It makes those absolutely tremendous I-6 noises, and is easy to service and fix. It's also getting worth more money instead of less.
We all have our own path, but I'd take the easy route on this one. If you want to chop up and engine swap a car, I'd start with a different chassis.
If you're just looking for a fun weekend car, do a budget rebuild of the original motor but use one of Richard Good's GP2 cams and do a 9:1 compression bump. That's what my drivable TR6 has, and it's entertaining enough and fairly reliable.
The big problem with upping engine output is that the diff mounts aren't really up to stock levels of power. If it hasn't already been done, plan on boxing in the diff mounts. For anything over 180 hp, I'd also swap in a Nissan LSD diff and upgrade the axles. Whatever you do, ditch the stock rear hubs for something stronger.
Have seen one with a small block (302ci)Ford. Engine compartment appeared to be wide enough although the firewall had to be cut for some extra room. This had a 4 speed but maintained the stock T6 differential which owner said was weak point and limited how much abuse he could apply. Small block ford weighted less them stock engine I was told.
Was going to link you to a great Miata 1.8 swap that a gal did on the Miata.net swap forum. Very clean and civilized result.
Maybe too tame for most people.
Sadly, the 32 page build got wiped by the photobucket scam.
Rebuilding the stock engine is definitely on the table.
When considering swaps, increased output wasn't really the goal. I was more interested in lightness and reliability, which is why I was looking at 100 hp 4-bangers from Suzuki and Mazda.
The stock TR6 engine does sound great. A stock rebuild might be the best choice.
Regarding 100hp I4's: At similar peak power, I don't know that I'd want to trade a ~33% peak torque reduction for a ~5% vehicle weight reduction.
NA 13B or stock build. Both sound great.
Head over to British V8 site for some inspiration. Problem with upping the engine anti is now you have to address every other issue the extra power brings on. If it were me, I'd stick another better straight six in there. Maybe a turbo BMW or a Toyota Supra engine. Really don't like TR6s so my opinion shouldn't be taken too seriously. If you want to talk about dropping an LS3 into a TR8, then I'm your guy.
Jumper K. Balls wrote: The Triumph 2.5 engine weighs about 450lbs and makes a staggering 124hp. It is a counterflow head design and has a big old anvil shaped counterweight in the center of the crankshaft that limits the motor to just over 4000rpm.
This! I have seen a couple of pictures of BMW swapped TR6s, the S50/52/54 sits in that bay like it was designed to go there.. Just be sure to upgrade everything else if you go that route. While the S52 only developed 240ish hp, the S54 went to 330. I doubt lightly modded TR6 brakes and suspension could handle that much oomph
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