triumph 2500s twin carb engine in to gt6

[Richard B]

GTEVO wrote:

Most of it, is down to the 2L having a MUCH better cylinder head than the 2.5L.
The 2L ideally should have been made as a 2.2/2.3L, it then makes a true sports car, something which a lorry engined car will never be....  ::)

Gareth are you saying the TR5 is not a Sports car?   :o

[Clive]

My vitesse was driven pretty hard, no problem. Just not into the 7000rpm thing, personal choice.
But compare it with a similar 2 litre, it will leave it for dead. Friend of mine used to go the same way to work, up a great hill. He was always gobsmacked by my car, and he was into all sorts (currently RS500).

Fuel consumption is pretty much the same as my old GT6 I had years ago, maybe 1-2 mpg worse, but marginal.
And it is all down to personal choice, the majority of my 6 cylinder mates (all I think) drive 2.5's in spits. There are a couple of GT6's being put together, and they both haven't yet driven them as 2.0, one is already sniffing round my zetec. The other, well I suspect he will be glad to get his car on the road!!

And I repeat, the only valid RR comparisons are done back to back, Or at least same RR, operator etc etc.
The results in the mag really show that a)much time, effort and money are wasted in the pursuit of power, b) the bolt ons do not do as much as claimed and c) Triumph were probably optomistic in the first place.
RR are very useful for getting the most out of an engine, Sadly no adjustmants made to amost of the cars on the day we did the shootout.


Clive

[JohnD]

Clive,
IMHO, and this supports tim's point, a 2500 engine desperately needs bigger wheels than the 13" of Spits/GT6/Vitesses. IE, 15" a la TRs & saloons.   Without them, they need very high geared transmission and/or an overdrive.
   Like you, I limited to the Sb to 6K and although it never ran out of puff, it would hit the rev limiter before the end of a longish straight, and that was with a 3.89 AND O/d.   While an O/d is not ideal in a race car, the 3.27 could be ideal for such a torquey engine, if it were not for the impossibility of fitting an LSD.

BUT, I read in the latest Courier that TLD has been building an LSD'ed 3.27 for exactly this reason.  I shall look on with great interest.

GT?  I have no doubt you'll have an opinion aabout a TLD project!

John

[Spitfire2500]

JohnD wrote:

Clive,
IMHO, and this supports tim's point, a 2500 engine desperately needs bigger wheels than the 13" of Spits/GT6/Vitesses. IE, 15" a la TRs & saloons.   Without them, they need very high geared transmission and/or an overdrive.
   Like you, I limited to the Sb to 6K and although it never ran out of puff, it would hit the rev limiter before the end of a longish straight, and that was with a 3.89 AND O/d.

Interesting. My Spit is very much set up as a road car, uses the 3.63 diff + O/D (and slight undersize 185/60-R13 tyres). A few laps at Knockhill a few years demonstrated exactly the same thing. Even on the short main straight at KH I was just hitting the rev limit in O/D top (which I restricted to 6k also) rather than running our of puff  :o Pretty damn scary -- but fun (much more fun than the MGF trainers I'd driven there previously) :o

But I'm happy enough with the set-up for a road car -- no need to change IMHO but can understand the point from a racing perspective.

Agree with Clive -- I'm not really into the 7k thing either. More in to the GT -- Gran Turissmo -- thing myself. Long runs north and south... :D

[ncoll]

JohnD wrote:

ncoll,
It HAS to be power at the wheels, unless the engine is on an engine dyno, and Dennis's is a rolling road.  So, 125 at the wheels NOT the flywheel.

Today i spoke to duncan campbell who is one of the mechanics at dennis vessey's rolling road, and he confirmed that what i had written earlier was correct. The power plot graph you have is the fly wheel brake horse power and torque. This is achieved by accelerating the car in 4th gear on the rollers where the computer programme records the wheel brake horse power throughout the rev range. When brake horse power has peaked the car is put in neutral gear and allowed to coast down and the computer programme records this, it then adds the two together and comes up with the torque and brake horse power at the fly wheel.

Neil Collingwood

[JohnD]

Neil,
In which case why has Dennis hand written in the form "140" - the rest is illedgible.
If the graph documents flywheel power (pace GT) at 125, then what is this higher figure?  Power at the piston heads?  Indicated mean effective pressure?
Maybe DV has a new rolling road?
I didn't see anything like a "computer" when I visited in, AFAICR, 2004.

GT,
No argument with your words about RRs, and Neil's may indicate that the DV RR has been replaced since that run.  It was looking, shall we say, well used so may have been on its last legs.    Despite what you said about the readout, and no argument there either, the other means of power comparision, other people who drove it, were complimentary.    So like the other RR, Rolls Royce, I am content with a performance that is "Sufficient".

John

[James]

Picton's old Green car (2.5PI spit) had a 3.27 on OD - and was wonderful to drive... a totally brutal beast...

Gearing was perfect...

[Clive]

Interesting, I have broken 2 or 3 3.27 diffs, always teeth. Always on hard acceleration, the last one in first (saloon box) on a roundabout.
So a late dolly or TR7 diff in a spit etc housing, will that work. Also want a longer first gear, hoping my spare dolly sprint box can be made to fit the shorter saloon input shaft?

Clive

[James]

I have no idea how long it lasted as it wasn't my car - I only got to drive it by invitation ;) - as far as I know it lasted a good few years of abuse.

It had a saloon gearbox with longer first gear - which may have helped.

[DoZ]

I now have my eye on a couple of 2.5L engines but can anyone tell me the difference between a 2500 and a 2500s engine.  Someone told me the s was due to the head being flowed.  Is this true?  Were there any other mods?  Getting more and more tempted by this option :-)

Every decision I make at the moment seems to end up costing me :-(

[jango]

3.63 is better i have found for track days etc