TR250 winter project?

[mleyland]

I have a TR250 on the original twin Strombergs. I'm not looking to go very very fast, but it is a sports car after all so I'm thinking about a change. Better fuel economy would be useful too.

 

The way I see it there are 3 options.

 

A shiny new pair of SUs like this: http://sucarb.co.uk/conversion-replacement-sets/triumph/pair-of-hs6-carburettors-for-a-triumph-tr6-tr250-usa-spec-conversion-set-from-cd-strombergs.html

Original-ish insofar as found on other Triumphs, and won't look out of place, but not really much extra oomph - not taking the sites claims as gospel. Should be easy to do, and easy to change back should I ever want to sell (unlikely in all honesty).

 

Convert to TR5 spec Lucas mechanical PI. Again, original-ish, though I don't like the idea of trying to dress it up as something it's not. More powerful, though probably no less thirsty. Temperamental perhaps? Not sure how easily available the parts would be either.

 

Left field option: efi, something like this:

https://sites.google.com/a/mintylamb.co.uk/triumph2000efi/home

You've got to think it would be more powerful and less thirsty than either of the other options - two ticks. Nil points for originality, although doesn't look totally out of place. Not easily reversible, but how important is that?

 

Anyone like to chip in with an opinion?

[had17462]

Hi, if you do go down the efi route I how a complete system from a Vauxhall senator £150.

Nick

[oldtuckunder]

If its an unmodified 250 then your compression ratio is probably 8.5:1 you are likely to see better performance from some head skimming work and refurbished existing carbs. Your not going to do much with an 8.5 head.

 

Alan

[AL TR250]

If its an unmodified 250 then your compression ratio is probably 8.5:1 you are likely to see better performance from some head skimming work and refurbished existing carbs. Your not going to do much with an 8.5 head.

 

+1

 

I was told changing to a TR6 head was the easiest way to boost power- better compression and more efficient porting. If you need to, it is also an opportunity to get hardened valve seats for an unleaded conversion.

 

Ali

[mleyland]

Hasn't thought of that, will give it some consideration.

[YankeeTR5]

You can skim your 250 head to bring it up to PI spec compression. Not that big a deal and will waken up the performance of the car considerably. You can also change the piston/damper in the carbs to take adjustable needles (250/early 6 North American model were non-adjustable for mixture) which will help tuning the car considerably. Can be as simple as finding some old Zeniths and swapping out the dampers.

Bear in mind that the intake manifold and head on the 250 has a narrow spacing that is different than the PI head (and later NA TR6 models - post 72 I think). So if you put a PI head on you will need to find a later intake manifold as well. Otherwise the ports of the intake and head will overlap by about 25% and your performance will be awful. I mention this as its an additional cost/complexity compared to just shaving the head you already have.

Best of luck with things

[mleyland]

OK, appreciate that. Sounds well worth investigating

[Tom Fremont]

I have a TR250 on the original twin Strombergs. I'm not looking to go very very fast, but it is a sports car after all so I'm thinking about a change. Better fuel economy would be useful too.

 

 

Not likely you'll ever get better mileage on this engine than the original configuration will make. With O/D it should be capable of 40 mpg ( Imperial ) on the highway. The non-adjustable emissions carburetors are set up for maximum efficiency. SUs won't improve on them at all on performance either, unless you enrich the mixture and decrease the mpg.

 

I put a Kent cam in my first '250, milled the original [ narrow port ] head and fit Weber DCOEs. The engine was transformed, and a mechanic who was working for The Roadster Factory rode in it told me it ran better than the company TR5 on PI. This was 20+ years ago. After that cam failed, and another of the same after it, I got a wide port head with porting, etc., a tubular exhaust manifold and P.I. cam. Still running with that recipe 80K miles later with no end in sight. It will outrun a stock TR5 in the 1/4 mile, time and MPH. But the fuel economy is 25% less.

 

Cheers,

Tom

[Brian Damage]

Bolt on supercharger kit ? You then un-bolt and sell if you decide to move the car on ? Should work well with the low-compression lump. Will do stuff all for your mpg but the grins and noise will be epic !!

[mleyland]

Haha, not exactly what I had in mind but thanks anyway :-)