TR6 TR6 Fuel Injection

[Morris]

I am raiding over from the Spridget list, but I thought you fine TR folks might enjoy this link...

https://topshamautoparts.com/tr6/tbi_updateSep04.htm

 

[michalotti_tr]

I've corresponded with this guy and although the website doesn't say it, these TBI can be mounted on the TR2 - TR4A as well - pretty sharp setup I think!

 

[aeronca65t]

You guys may also wish to look here for a DIY, low-cost fuel injection system (there's also a forum associated with it for tech questions):

https://www.megasquirt.info/

 

[jerrybny]

Article was very interesting. Now if I can just get the wife to part with the money I'd be all set.

 

[vettedog72]

Now THAT's WHAT IM TALKING ABOUT1! An inexpensive fuel injection that will hold an optimum fuel to air ratio.

Any body got it?

 

[piman]

Hello all,

as someone who runs an injection Triumph, I think that the above is an interesting exercise but I doubt that it is significantly better than the original carburettor system as it retains the original manifold so has the same restrictions and fuel distribution drawbacks that the original six throttle body injection does not have.
There have been a few people over here who have utilised the Lucas throttle bodies and fitted electronic controlled injection systems.
While the Lucas mechanical system is very basic it does have the facility to be tuned without requiring a computer to so do.

Alec

 

[vettedog72]

If the system works as describe, it is 35% better in fuel management (avg 20mpg vs 27mpg). The even burn at 14.7 is incredible. All of this with a stock manifold. I don’t know the theory of manifold flow, but common sense would make me think the individual “tube” per cylinder with the same lengths from the atomizers would be superior to the conventional manifold (it would seem that cylinders 2 and 5 would all ways be rich vs. 1,3,4 and 6 with the stock manifold). On the other hand, I wonder how efficiently the stock PI system actually gets the fuel to air ratio over the normal RPM range.

Consequently, I am interested in how well the throttle body would perform vs stock carburetors, as this new FI system appears to cost a little more than the professional refurb of 2 carburetors.

Even more convincing would be before and after dyno test.

 

[piman]

Hello VD,

quoting fuel consumption is not a good indication unless you do a strictly back to back evaluation, ideally as you say on a Dyno. 14.7 to me is an economy value and not a performance one, so that is one factor. I would certainly expect some improvement in control with a sensor feed back system to control fuel but it is, of course, an average reading of all six cylinders. That is why I query the benefit and expense.
The original mechanical P.I. system is not as good as a computer controlled systems in controlling the mixture, I would say but from a performance point of view the six throttle bodies must be better than the 2 x 1 into 3. That is why there has been some discussion as how much better the triple carburettor set up is as the air flow is improved.

Alec

 

[Webb Sledge]

The sheer amount of hoses and wires running through the engine bay on that car scares me.

 

[vettedog72]

Your correct about the ratio, I was thinking ecologically (without cats, EGR’s etc that may reduce the power performance and add maintenance problems). There is no one air/fuel ratio where all emissions are minimized. At an air/fuel ratio of 14.7:1 oxides of nitrogen peak, while hydrocarbons and carbon monoxide (CO) increase substantially as the air/fuel ratio richens.

Bosch states that most spark ignition engines develop their maximum power at air/fuel ratios of 12.5:1 - 14:1, maximum fuel economy at 16.2:1 - 17.6:1, and good load transitions from about 11:1 - 12.5:1. However, in practical applications, engine air/fuel ratios at maximum power are often richer than the quoted 12.5:1, especially in forced induction engines where the excess fuel is used to cool combustion and so prevent detonation. I wish I were at that point of concern.

My interest in the new system is the simplicity (fewer parts vs a complicated system as noted by Webb Sledge), low cost (initial cost and up-keep) and apparent reliability (pump failure on PI’s are pretty common). The technology advances of the new system are, no doubt, a significant improvement over the old PI (feed back for control for one). The ultimate tuning of each system to produce the most power could be a continuing challenge. I am interested in a system that would give maximum power and good behavior when starting cold, stop and go driving as well as spirited driving. For me, there is no doubt that a separate injector for each cylinder would be an improvement, especially if they are monitored and controlled electronically. How does the PI compare to these requirements?

 

[piman]

Hello VD,

there is no comparison between modern electronically controlled injection systems and the old mechanical system.
What I queried initially was that I did not think there would be a significant benefit over the twin carburettor system, in terms of performance, with a much more complicated and expensive set up.
The reason that Triumph went to the injection system was because of the then stringent emmission regulations that America introduced and it was felt that an injection engine would be the way to go. In the event it didn't work as they thought and Triumph found that they could meet the required regulations with the Stromberg carburettors.
The injection engine, however, was a powerful engine which the British market was fortunate to have all because of your emmission regulations

Alec

 

[Rabid_Dolphin]

I think part of the modern FI allure that entices the carbed crowd comes from the element of computerized control as much as the actual injection. Modern fuel systems incorporate not only fuel curves(and usually indv cylinder injection) that automaticaly adapt to load and ambient environmental variations, but also alter timing to increase power and decrease detonation in all scenarios. heck, I can even program a seperate fuel/timing table that would go into effect should I get a tank of crappy gasoline. That tends to be a little more difficult with a distributor. The benefits of a good TR6 system would include better gas milage, more power, easier cranking, and better overall driving manners. Having said that, I don't think a really good FI system has been produced for this application. I think two things really hold back the benefits of any induction system on this engine: manifold design and lack of ignition control. Honestly, I don't think the side draft design is such a hot idea. Even if you could get the air flowing well enough through the runners, I don't think the imperfect atomization of the mixture allows it to behave in a beneficial manner over such a horizontal distance.

Now, if you could pop an injector into the runner of each cylinder and angle it towards the head, I think you would be in business even without ignition control. You could still use TBs and maybe a speed density unit to meter the air on the end of the manifold, you get the charge moving the length of the runner without the impedence of (comparatively)poorly atomized fuel, then hit it with nice, FI, computer controled, atomized fuel as its entering the head. There may be some trouble with the the angle of injection and the angle of the port entering the head. I would hope it could be minimized.

That may not be the most practical approach, but I think it would help with one of the major drawbacks of the TR6 induction system. Next up: putting the frigging exhaust ports on the other side of teh head.

 

[Rabid_Dolphin]

[ QUOTE ]

The injection engine, however, was a powerful engine which the British market was fortunate to have all because of your emmission regulations

Alec

[/ QUOTE ]
We do what we can. /ubbthreads/images/graemlins/laugh.gif

 

[martx-5]

[ QUOTE ]
...
The reason that Triumph went to the injection system was because of the then stringent emmission regulations that America introduced and it was felt that an injection engine would be the way to go. In the event it didn't work as they thought and Triumph found that they could meet the required regulations with the Stromberg carburettors.
The injection engine, however, was a powerful engine which the British market was fortunate to have all because of your emmission regulations

Alec

[/ QUOTE ]

From what I understand, the mechanical FI'ed 6 cylinder engines produced about 150 hp. That's almost 50% more power then the carburettor counterparts. I find it difficult to believe that the increase was just due to the injection system. There had to be other differences such as compression ratios, cam lift and timing, etc. that accounted for the increase.

 

[Hayfever]

[ QUOTE ]
From what I understand, the mechanical FI'ed 6 cylinder engines produced about 150 hp. That's almost 50% more power then the carburettor counterparts. I find it difficult to believe that the increase was just due to the injection system. There had to be other differences such as compression ratios, cam lift and timing, etc. that accounted for the increase.

[/ QUOTE ]

According to this article from 1991 the PI cars have 9.5:1 compression (US cars had 8.5:1 or 7.75:1 depending on year) and a hotter cam.

 

[Hayfever]

[ QUOTE ]
Now, if you could pop an injector into the runner of each cylinder and angle it towards the head, I think you would be in business even without ignition control. You could still use TBs and maybe a speed density unit to meter the air on the end of the manifold, you get the charge moving the length of the runner without the impedence of (comparatively)poorly atomized fuel, then hit it with nice, FI, computer controled, atomized fuel as its entering the head. There may be some trouble with the the angle of injection and the angle of the port entering the head. I would hope it could be minimized.


[/ QUOTE ]

That's what I did for my Megasquirt setup. I used a set of PI manifolds that I removed the butterflies from and used a single throttlebody on the airbox. I'm also planning on drilling a carb manifold for a friend which will be fitted with twin throttlebodies.

 

[Rabid_Dolphin]

[ QUOTE ]


That's what I did for my Megasquirt setup. I used a set of PI manifolds that I removed the butterflies from and used a single throttlebody on the airbox. I'm also planning on drilling a carb manifold for a friend which will be fitted with twin throttlebodies.

[/ QUOTE ]

That sounds pretty sweet. What are you using to control the injection and mixture? The PI manifold sounds like it would work fine, but I was thinking more along the lines of the carb manifold you are talking about with twin TBs.

 

[Hayfever]

I'm using Megasquirt for fuel control initially, then adding spark control once I have the fuel control tuned well.

For the carb manifold, Datsun 300ZX's have twin throttlebodies that are almost bolt-on to the TR6 carb manifold. Note the ALMOST. /ubbthreads/images/graemlins/smile.gif That's what's holding the carb manifold back, I haven't decided whether to redrill the manifold studs or redrill the TBs.

 

[Rabid_Dolphin]

[ QUOTE ]

Note the ALMOST. /ubbthreads/images/graemlins/smile.gif That's what's holding the carb manifold back, I haven't decided whether to redrill the manifold studs or redrill the TBs.

[/ QUOTE ]
Which is cheaper? /ubbthreads/images/graemlins/grin.gif

 

[Hayfever]

Well, since I got the manifold for free, the TB's for free, and have free access to a vertical mill......

I've got ~$300 into my PI manifolds including purchase and I like the way they look a lot better than the carb manifold would, but that's just me.