Triumph Spitfire

[fujioko]

Hi,

The Suzuki G10 3 cylinder and a Samurai transmission is small enough to fit in a Spitfire, however the intake manifold might be a problem.

I also own a Triumph Spitfire and I kicked this idea around for a while. I'm pretty sure you'll see a 200 pound weight reduction with the swap.

I ended up putting a G10 engine in a Mazda Miata... a significantly heavier car.
The performance is certainty slower but the fuel economy is awesome.

I get 45 + MPG real world driving and can squeeze out over 50 MPG with modified driving.

I drive the G10 Miata regularly and I'm still experimenting with mods to improve real world fuel economy.

[fujioko]

I posted in the wrong thread. Disregard this entry.

[GreenHornet]

I think I am qualified to try and answer this question as I have 2 GT6 cars and am building a diesel electric hybrid based kitcar from the Triumph Spitfire/GT6 chassis

I am going to try and be objective here as I am biased to diesel!

First it depends on your goals and objectives. If its gonna be a one off build only for you and if it is to simply get better fuel economy than you can not ignore a small displacement diesel such as what you may come to find in the VW 1.2L Lupo or 1.4L Polo another option is the 1.3L CDTI found in the Opel Speedster cars and the famous Eco Speedster! The Smart car diesel will not work as I have all ready spent the time exploring that option so no need to waste your time with that!

If you live in the states it will be tough to source these engines but I do have a friend who imports these engines and can help but I will say right now they are not cheap they are new crate engines from VW. So expect to pay north of 4 grand for them.

If you went the used diesel engine route you could get older VW 1.6L TD engines super cheap under 1 grand and they will give you 60mpg or better all day in a Spitfire with stock transmission. If you wanted to upgrade the transmission to something more modern than I highly recommend a T5 transmission. They can be found cheap and have literally tons of custom options available to the DIY builder. This would net you even better MPG and performance if modded correctly out of any engine you decide to go with!

Now for the objective part I guess that means gas options LOL

Some have mentioned all ready Geo and Honda. The Geo is light and cheap. The Honda is lighter and well its Honda you get reliability for an increased cost over the similar displacement Geo Metro engine. If it was me I might try and hold out for the Ford 1.0L Ecoboost engine as it is a gassers dream engine in my opinion! You can mod that little thing to over 200hp and still get more than 50mpg!

Here is a link to an article that talks about the engine being offered in the Fiesta for the US market = Ford Details 1.0L EcoBoost 3-Cyl Engine for U.S.-Spec 2014 Fiesta | Car and Driver Blog

Here is a must see video of it in action =

http://www.youtube.com/watch?v=tmZMwk14r4c

GH

[GreenHornet]

Now for the bad news!

If you try and put anything in the Spitfire with increased levels of Torque over stock say North of 150 Torque you will destroy your rear differential in short order! They were built weak and not designed to handle much more than stock. The GT6 later differentials in the MK3 were stronger but still will not stand up to constant punishment from a torque increased engine. There are modifications you can make to these differentials to net even more increased strength but it will never stand up to a modified high output street or racing engine!

The other issue is the swing spring in these Spits they are dangerous under high acceleration they cause jacking which is not a pleasant feeling when you are driving to say the least. The later GT6 MK2 and MK3 went to a rotoflex suspension and vastly decreased this jacking effect but did not do away with it! You still had it with high output engines over stock!

If you want an engine that is gonna be high output diesel or gas you will need to sort out these 2 key variables as they will be show stoppers for you guaranteed.

My TIGON diesel electric hybrid GT4 model is using a VW 1.9L TDI with a T56 6 speed transmission. Currently I am trying to sort out the rear end as I stated above its not meant for this kind of torque! Many people have swapped in R160,R180 Suby and Nissan diffs with great success. So you might check into that as an option. There is lots of info flying around the net in Triumph circles on this upgrade.

The other thing to also keep in mind is the Spitfires can easily upgrade the breaks from the GT6 models as parts are easily swapped between the 2 cars. If you go with a higher output engine I would highly recommend swapping your brakes for a GT6. They are bigger and will help you cope with the increased power levels better resulting in a safer and more reliable ride.

GH

[mozul]

One thing you can think of to reduce the tuck under for the rear suspension on the Spitfire is adding a Camber Compensator. This is a kit you can get here It is an additional spring that mounts to the bottom of the diff and the bottom of the Wheel mounts to reduce the tuck under. I have it on my car and it works well.

[Frank Lee]

I put a '68 Toyota Corona engine in my Spittie and promptly broke a couple of those toothpick half-shafts, and I never even got on it hard. What a piece of junk.

[GreenHornet]

Hey Frank,

The Spitfire axles were super weak! it is no surprise you snapped them in to. The rotoflex system was much improved over the spitfire system however still weak in my opinion.

They eventually came out with a CV kit that fixed the single U joint issue and turned it into a true IRS. However I still do not trust those CV axles for increased torque above and beyond 200 ft-lbs. The axles are real spendy also I would hate to test them out and bust em

This CV kit still did not solve the weak differential problem!

GH