Discussion
Random question for a wet afternoon.
The Stag V8 has it's enthusiasts and detractors, it's a pretty engine, can be reliable if looked after. Not overly stressed in standard form.
There's a number of re-engined cars come up for sale at a much reduced price, some with the Rover V8 which I know about having owned a number of TVR but also the Triumph 2.5 straight 6 which at least keeps it in the family.
Obviously you lose the V8 "woofle" but you save the cost of two spark plugs (ha ha).
What are the real world disadvantages (or advantages) of the straight 6?
The Stag V8 has it's enthusiasts and detractors, it's a pretty engine, can be reliable if looked after. Not overly stressed in standard form.
There's a number of re-engined cars come up for sale at a much reduced price, some with the Rover V8 which I know about having owned a number of TVR but also the Triumph 2.5 straight 6 which at least keeps it in the family.
Obviously you lose the V8 "woofle" but you save the cost of two spark plugs (ha ha).
What are the real world disadvantages (or advantages) of the straight 6?
It sounds from your few words as though you have a good understanding of the Stag.
All I would say is that any classic car is worth more ££ if it hasn't been "buggered about with". And any engine that's not original is going to fall substantially within that category.
I perceive the Triumph 2.5 as having been pretty good back in its day although I've never actually driven one. Presumably if it was good enough for the TR6 it ought to be able to get a Stag moving up the road.
As ever, buy on overall condition. A cheap Stag can be the very definition of a money pit. As it happens my Stag had its original engine but, for some reason, a Triumph diff. Go figure.
As you probably appreciate the oily bits are relatively easy to sort out. But if you get one with a dodgy body or interior you could be heading into a whole world of pain.
All I would say is that any classic car is worth more ££ if it hasn't been "buggered about with". And any engine that's not original is going to fall substantially within that category.
I perceive the Triumph 2.5 as having been pretty good back in its day although I've never actually driven one. Presumably if it was good enough for the TR6 it ought to be able to get a Stag moving up the road.
As ever, buy on overall condition. A cheap Stag can be the very definition of a money pit. As it happens my Stag had its original engine but, for some reason, a Triumph diff. Go figure.
As you probably appreciate the oily bits are relatively easy to sort out. But if you get one with a dodgy body or interior you could be heading into a whole world of pain.
Cheers, yes appreciate the originality thing.
It's just while perusing ads, I see the occasional 2.5 and wonder what the real world differences are. Similar BHP, but has the V8 more torque? Power in a different area on the rev band? Is the straight 6 lighter or heavier affecting balance....?
It's just while perusing ads, I see the occasional 2.5 and wonder what the real world differences are. Similar BHP, but has the V8 more torque? Power in a different area on the rev band? Is the straight 6 lighter or heavier affecting balance....?
A lot depends which flavour of the 6 is used.
In general it will be one from a 'big saloon' rather than a TR, so put you in the 99 to 106 bhp band by default. It could be a carb-converted PI engine which I think has a hotter cam so gives you a bit more, and on rare occasions could actually have all the PI kit transferred over, in which case you're looking at 124/132 bhp. For reference the Stag v8 puts out 143 bhp - which is basically what you're looking at if you convert a PI to EFi (along with the ability to start on all 6 cylinders, not on 3 or 4 and wait for the others to realise they've been left behind).
Of course one thing not to overlook these days when it comes to buyinig an engine swap classic is when was it done/what supporting evidence comes with the car regarding the engine swap date, as while this DOESN'T impact on historic tax status it can impact the MOT exemption status.
From memory a Rover v8 conversion needs to have been done at least 30 years ago.
You get more leaway when it comes to the Triumph 6 as there's also a something like "or also done by the manufacturer in the day" condition - but while that covers swapping a 2.0 six for a 2.5 one in a big saloon (where Triumph sold both 2.0 and 2.5 sixes) the v8 to 2.5 six swap would need a chat with the DVLA or whoever. From memory Triumph DID fit some Stags with the 6 cylinder engine for testing/evaluation they didn't sell them so a greyer area.
In general it will be one from a 'big saloon' rather than a TR, so put you in the 99 to 106 bhp band by default. It could be a carb-converted PI engine which I think has a hotter cam so gives you a bit more, and on rare occasions could actually have all the PI kit transferred over, in which case you're looking at 124/132 bhp. For reference the Stag v8 puts out 143 bhp - which is basically what you're looking at if you convert a PI to EFi (along with the ability to start on all 6 cylinders, not on 3 or 4 and wait for the others to realise they've been left behind).
Of course one thing not to overlook these days when it comes to buyinig an engine swap classic is when was it done/what supporting evidence comes with the car regarding the engine swap date, as while this DOESN'T impact on historic tax status it can impact the MOT exemption status.
From memory a Rover v8 conversion needs to have been done at least 30 years ago.
You get more leaway when it comes to the Triumph 6 as there's also a something like "or also done by the manufacturer in the day" condition - but while that covers swapping a 2.0 six for a 2.5 one in a big saloon (where Triumph sold both 2.0 and 2.5 sixes) the v8 to 2.5 six swap would need a chat with the DVLA or whoever. From memory Triumph DID fit some Stags with the 6 cylinder engine for testing/evaluation they didn't sell them so a greyer area.
Edited by //j17 on Friday 7th October 11:02
//j17 said:
Of course one thing not to overlook these days when it comes to buyinig an engine swap classic is when was it done/what supporting evidence comes with the car regarding the engine swap date, as while this DOESN'T impact on historic tax status it can impact the MOT exemption status.
Now that's something I didn't realisePanamax said:
Good point.
Whichever way you go, watch out for the fuel consumption. Obviously not a big deal if you only do 1,000 miles a year but there's a hell of a difference between 19 mpg (Stag 3-speed auto, driven gently) and 50 mpg (modern hatchback at motorway speed).
Fuel consumption of a 2.5 six is about the same as the Stag.Whichever way you go, watch out for the fuel consumption. Obviously not a big deal if you only do 1,000 miles a year but there's a hell of a difference between 19 mpg (Stag 3-speed auto, driven gently) and 50 mpg (modern hatchback at motorway speed).
One other observation, that I think I made on another thread the other day, is that the Stag was originally designed around the straight six. The Stag's manual gearbox is essentially the same as a TR 5/6. The V8 was considered to give driving characteristics more suited to a GT and – most importantly – be more attractive in the US market. Ironically if they'd stuck with the six until the V8 was sorted they'd have probably sold a lot more Stags.
When my uncle was buying his Stag (a long time ago now admittedly) the Triumph 6 conversion had quite a few fans among the cognoscenti. As noted above, car was designed around that engine, and being cast iron the weight is about the same as the Triumph V8 whereas the Rover engine is lighter, which was reckoned to affect the handling by some.
Never owned or driven a conversion of either stripe however so can't comment directly.
Never owned or driven a conversion of either stripe however so can't comment directly.
Yertis said:
One other observation, that I think I made on another thread the other day, is that the Stag was originally designed around the straight six. The Stag's manual gearbox is essentially the same as a TR 5/6. The V8 was considered to give driving characteristics more suited to a GT and – most importantly – be more attractive in the US market. Ironically if they'd stuck with the six until the V8 was sorted they'd have probably sold a lot more Stags.
That's interesting, Yertis! But, by that time, TRiumph was associated with BMC, which had the Rover V8 (ex-Buick) engine well established, developed and ready to drop into the Stag. But no, they had to go ahead and develop their own V8. Then, in typical Triumph penny pinching mode they didn't train the dealers about bi-metallic corrosion and the need for protective antifreeze all year, which crippled the reliability rating of the engine. Just like Lucas Pi!John
tapkaJohnD said:
That's interesting, Yertis! But, by that time, TRiumph was associated with BMC, which had the Rover V8 (ex-Buick) engine well established, developed and ready to drop into the Stag. But no, they had to go ahead and develop their own V8. Then, in typical Triumph penny pinching mode they didn't train the dealers about bi-metallic corrosion and the need for protective antifreeze all year, which crippled the reliability rating of the engine. Just like Lucas Pi!
John
Now you're just opening up the old "Triumph refused to use the 'Rover' v8" / "Rover refused to let Triumph have 'their' v8" argument! John
With the truth being multiple governments wouldn't let <insert random collection of letters being used that week> do what they needed to to ensure long term survival of the British car industry, which was kill off 75% of the brands and staff, so different parts of the same company spent more time and effort fighting one another that keeping up with the rest of the world.
Edited by //j17 on Tuesday 11th October 15:16
I have a Stag and had 2.5S Estate for about 10 years. Carbs, Mk1 PI cam, big bore Chris Witor exhaust - it went pretty well and sounded pretty good.
...but nothing like as good as the Stag.
The Stag V8 revs more freely, feels quicker and more engaging.
At least 50% of the Stag's appeal is the exhaust note. I can't think of any other standard production car of the period, except maybe some TVRs* that sounded so good, even when just idling.
A Stag without an original V8 is not really a Stag.
...but nothing like as good as the Stag.
The Stag V8 revs more freely, feels quicker and more engaging.
At least 50% of the Stag's appeal is the exhaust note. I can't think of any other standard production car of the period, except maybe some TVRs* that sounded so good, even when just idling.
A Stag without an original V8 is not really a Stag.
- Were TVRs ever 'standard' ?
Panamax said:
Ain't that the truth. It was my first V8 and gave meaning to the word "burble"!
They (the original V8) do make a wonderful sound. Back in the day when I had a couple the exhaust note changed somewhat for the better when the timing chains were replaced as the design made them quite long and so when stretched the cam timing was affected, hence the different exhaust note. 
I’ve never really understood Stags, they’re a tarts handbag. They’ve got the team Triumph 70’s looks but a bit camp. A Dolomite Sprint or 2500TC looks far better IMO. And they’re definitely no ball of fire and as for engine issues ?! TR5/6 for performance so where does that leave it ? ‘It sounds nice ….’
Each to their own etc
Each to their own etc
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