TIGON Diesel Hybrid

[cRiPpLe_rOoStEr]

Altough CNG has a lower energy content than Diesel fuel, being sprayed at the intake it can also act like a chemical intercooler, thus enhancing the efficiency of the combustion process of the regular Diesel fuel.

[Grant-53]

Check with the engine manufacturer to see what options they recommend for Turbo and CNG. There has a lot of research being done and new injectors have been designed for urban buses and locomotives.

[GreenHornet]

Originally Posted by cRiPpLe_rOoStEr

Altough CNG has a lower energy content than Diesel fuel, being sprayed at the intake it can also act like a chemical intercooler, thus enhancing the efficiency of the combustion process of the regular Diesel fuel.

Hey CR,

Yes this is true but not to the degree as methanol does. However you get much more power boost from CNG than you would from Methanol/Water injection. You may even get enough power from the CNG conversion to completely eliminate a turbo or super charger system thus saving you money and time!

[GreenHornet]

Originally Posted by Grant-53

Check with the engine manufacturer to see what options they recommend for Turbo and CNG. There has a lot of research being done and new injectors have been designed for urban buses and locomotives.

Hey Grant-53

I will definitely look into it for sure thanks for the post.

GR

[GreenHornet]

Today I began working on my wheel and hub modifications. The plan is to use the 3 X 112 Smart wheels on the car. The main reason being is they are light and cheap. The other main reason is they are virtually the same offset and stock width as the GT6 making it an ideal option for Spitfire and GT6 owners who are looking for a very light weight 15" wheel.

I was looking at Canley Classics as an option for there alloy hubs as they stated they could be supplied as blanks but further investigation with them led me to the conclusion there hubs would not be big enough for a 3 X 112 bolt pattern to be drilled out.

So this leads me to 2 options which are

#1. design and fabricate my own custom hubs to accept the Smart wheels.
#2. design and fabricate hubcentric wheel adapters for the existing hubs so that the Smart wheels can be utilized.

It is my belief it will be much cheaper and faster to go with the second option. So this is the route I am going to pursue first maybe later I will try and tackle the custom hubs.

There is always compromises on these projects and it always amazes me what I initially set out to do and what actually ends up happening

One might ask why go through all the time and effort on this one aspect of the car but I strongly believe that reducing unsprung weight in a vehicle is very important and even more so on a lighter vehicle as Tigon. The rule of thumb is a 6:1 ratio meaning for every pound of unsprung weight you lose it would be like losing 6 pounds of sprung weight. This is a conservative factor as Porche seems to think its more like 7:1

So the little extra time and effort here can pay huge dividends. Since I am in no rush to finish up this project I figure why not take the extra time and get it just the way I want it. In the end I believe I will be more happy with the results and have a highly desired commuter supercar.

[GreenHornet]

Today was a day of planning and going over the initial designs. While initially wanting to go with a 3 wheeled reverse trike on this I have decided to change things up and keep it 4 wheeled. The main reasons are I think the 3 wheeled design would be better represented with its own chassis design from scratch. Another reason is I like the idea of recycling and reusing the parts I all ready have on hand. This cuts costs as well as time which are both key to a successful and completed project. This also cuts out the need for chassis modification so the stock chassis is all that is needed to get a rolling chassis going. Cuts out the amount of foreign parts that need to be sourced which is often unpredictable and time consuming. In my mind this simplifies the reproduction ability and also creates the opportunity for an highly aerodynamic body shell that can be bolted to any Spitfire or GT6 opening the door for future kits if desired.

I also have a very well thought out plans guide in the Urba Centurion. While the plans guide is out dated it gives you a solid idea of the process and goes a little bit into component selection. The best part is there has been a few completed Centurions to date and all have similar specs as to the originally designed model. So for around $7,000 or less you can certainly have a 100+ MPG car in your driveway albeit at speeds around 50mph only.

GH.

[GreenHornet]

So whats the new plan?

The plan is to greatly improve on the Centurion design creating the Tigon diesel car. I will achieve this by superior aerodynamics, hybrid design, smaller turbocharged engine, overall weight reduction, improved part sourcing and superior gearing.

The Spitfires and GT6 cars have a solid parts sourcing community where its relatively easy to find stock as well as performance parts. I will be upgrading the parts I do not have and rebuilding and reusing the ones I do have with some exceptions. The wheels as stated in an earlier post will be upgraded to a 15" 10lb Smart wheel over the stock 13" 18lb steel units and the Centurion 13" X 6 wheels that are heavy and negatively contribute to rolling resistance. The front hubs, breaks, and shocks will all be upgraded to reduce weight and add strength and I need them anyways!

The rear end will stay stock all nuts, bolts, washers, shocks, and leaf spring will be replaced. Possible CV joint upgrade as well as lowering block will be used. I will use my stock 3.27 rear differential rather than try to locate the 3.89 diff in the Triumph Spit and GT6 overdrive units. This saves me money and gives me a big advantage with my gearing as you will soon discover.

I will still be using the Yanmar but in variable speed form and will be moving to a manual T5 5 speed transmission. They are cheap solid and easy to source. They are also easy to work on for the DIY guy like me. The are literally hundreds of combinations with this transmission which makes it ideal for a purpose built vehicle such as Tigon. When comparing the Centurion gearing to my proposed Tigon we have major advantages. Firstly we can purpose build our T5 to have better 0-60 acceleration over the 4 speed Centurion do to the lower 1-3 gearing with the T5 tranny. We also have a much taller overdrive which gives us big advantages during freeway cruising situations. The T5 is also lightweight and compact which makes it every bit as ideal as the original GT6/Spit tranny. The T5 is also much more durable and can handle much more torque which will be nice when the hybrid system is installed onto the Tigon.

For comparison the Centurion had the following gear ratios:

1st= 2.65/10.3 2nd= 1.78/6.92 3rd= 1.00/3.89 4th= .80/3.112 FDR = 3.89

Tigon proposed gear ratios:

1st= 3.75/12.26 2nd= 2.19/7.16 3rd= 1.41/4.61 4th= 1.00/3.27
5th= .63/2.06 FDR= 3.27

Again the advantage with the T5 is that these gears can easily be swapped if the need arises and there are tons of combinations and options for the builder as this was not the case for the stock Triumph transmissions used in the Centurion. Also having the fifth gear helps move gears 1-4 closer for better acceleration and in town usage with the smaller displacement Yanmar. The T5 also gives me a much taller final gear ratio of 2.06 which is ideal for freeway cruising and greater top end speed out of Tigon. The Centurions top end speed was only 65mph with its 3,000rpm 17hp 3cylinder Kubota. Tigon will have an estimated stock 2 cylinder 13.4hp diesel only top speed of 85mph and turbocharged will put it over 100mph! So here you can see Tigon doing more with less and will reap the rewards through vastly improved fuel economy compared to the original Spit/GT6 and the Centurion diesel variant.

As far as I know there are 4 different rear differentials that can be used which are:

#1. 3.27 this is stock and easiest to find
#2. 3.63 good option for acceleration and top end speed
#3. 3.89 typically used on the overdrive cars and used in the Centurion
#4. 4.11 typically seen on the track cars

This allows anyone down the road to further explore gearing options. This was one aspect that I did not like in regards to the Goldwing rear swingarm and rear differential. It had a 2.75 rear diff and that was it no other options available. Not to mention it would have made using a manual transmission difficult from a connection stand point. I think giving multiple differential options and simplifying the attachment of the drivetrain is a big improvement. No belts and chains needed just a solid heavy duty mechanical connection that will be more reliable and less maintenance.

[GreenHornet]

I want to take a moment and dive more into the gearing and its importance as it pertains to small tractor diesels such as the 2 cylinder Yanmar. Often times we see people swapping these engines into small cars thinking that they will get incredible fuel mileage. Few do and most don't and a big part of the reason is the gearing. Transmissions are mated to engines to compliment them and most of the time its a compromise even for the stock engine whether more acceleration or fuel economy was the primary focus. Rarely you get a stock tranny that gives you both performance and economy. So we are usually stuck with what we got and have to live with the powers to be. The trend recently has been to offer more gears in a way to improve fuel economy without sacrificing acceleration. For many cars this strategy has helped to a point but with more gears weight starts to play a factor and you get to the point of diminishing returns.

In order for a small 13.4hp Yanmar engine or any tractor engine for that matter to have good acceleration and great fuel economy you have to purpose build a manual transmission. The transmission needs to be relatively light, efficient, and have good gear swapping ability and options. This way we can have both acceleration and fuel economy. Now obviously this is not the only piece of the puzzle as weight and aerodynamics also play a huge factor but like the old saying goes you are only as strong as your weakest link. The saying definitely holds true when it comes to optimized gearing.

Another trend for car manufacturers in today's sub compact car market to use smaller turbo engines and couple this with lower 1-4 gearing and then give it 1 or 2 overdrive gears for increased fuel economy. A good example of this is the Honda Insight Gen 1 and the Chevy Eco Cruze. However the Cruze being a 3,000lb plus car actually utilized 3 over drive gears in its transmission to help give it its 50 plus freeway cruise fuel economy. Pretty good for a modern 5 seat non hybrid car that weighs over 3,000lbs.

So the candidates currently for the Tigon are the T5 which I proposed earlier and a T56 6 speed. Further investigation needs to be done to determine if a T56 will even fit into a small car such as the GT6. I have my doubts to be honest but the T56 would give some interesting options for the Tigon ecomodder.

For example a typical T56 gearing with a 3.63 rear diff may look like this:

1st= 2.97/10.78 2nd= 2.07/7.51 3rd= 1.43/5.19 4th= 1.00/3.63 5th= .84/3.04 6th= .56/2.03 FDR= 3.63

also can be like this:

1st= 2.66/9.65 2nd= 1.78/6.46 3rd= 1.30/4.71 4th= 1.00/3.63 5th= .74/2.68 6th= .50/1.81 FDR= 3.63

The dry weight of these units are 115 and 108 respectively compared to 75lbs for the T5 regardless of configuration. However you get 2 overdrives and a taller one at that for 6th gear. However you have far less options for gears 1-3 which is very important for a small tractor engine being used in a car application. So the rear differential would need to be bumped up to the 3.63 for adequate acceleration most likely. However by adding the electric hybrid option and turbocharging you might be able to comfortably get away with the taller 6 speed. From the stock Yanmar perspective the T5 gives you the best trade off between acceleration and economy at a cost effective price point. So if I was going to only keep it stock diesel than the T5 would be the best candidate in my opinion. If the length of the T56 is not prohibitive than in a turbo and hybrid design the T56 would give some interesting potential with better fuel economy potential despite the added size and weight.

T5 gearing specs = TTC: TREMEC Transmissions

T56 gearing specs = TTC: TREMEC Transmissions

GH..

[cRiPpLe_rOoStEr]

Originally Posted by GreenHornet

Hey CR,

Yes this is true but not to the degree as methanol does. However you get much more power boost from CNG than you would from Methanol/Water injection. You may even get enough power from the CNG conversion to completely eliminate a turbo or super charger system thus saving you money and time!

I wouldn't disconsider a turbocharger not even with the supplementary CNG injection, since it reduces the power loss in higher altitudes.

[GreenHornet]

Hey CR,

Yes you are correct most likely what you will see in the Tigon is a Water/Methanol injection system that helps support a turbocharger system! As much as I like the sounds of CNG injection, Methanol injection is more realistic and offers in my opinion more advantages with few downsides. Not to mention it is much cheaper and can be a DIY based project where CNG is much more expensive to set up as well as difficult for the DIY guy like me. CNG tanks also take up a lot of cargo space and being that Tigon is a small car I just can not see how I would fit a tank big enough to make a real appreciable difference over a methanol set up! I have been thinking about this a lot actually as I see this as a great way to help boost as well as protect the diesel engine over its lifetime. When working with a tiny diesel as I am every little bit of extra horsepower I can safely squeeze out of it will make a difference. I have yet to decide on what kind of turbo charger system I want to go with. There are some interesting candidates but nothing that so far takes the flag above all the rest.