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6 Cylinder Fuel Injection Conversion

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glemon

glemon

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Does anyone know if converting a US Spec car (TR250 in my case) to the later spec euro fuel injection as used the TR6 (I think it was supposed to give about 130 horsepower) is a simple (being a relative term) bolt on type installation of the fuel injection parts, or are there other modification that need to be made to the engine/car, I know it uses a different fuel pump, but that is part of the deal I am looking at.

P.S. I live in the US, but not in a smog state.
 
You need to talk to Alana. He'll be around when he sees your thread about fuel injection.

Just give him a little time.
 
The Euro-spec TR6 (PI) had a different cam and compression ratio in addition to the fuel injection. The original Lucas mechanical fuel injection was set up based on the engine having that cam and compression ratio. To get it to work on a US-spec car, I believe you will either need to go to the PI cam and compression or modify the fuel injection to work with your cam, etc. Of course, if you don't change to the PI cam and higher compression ratio, you won't get the performance of the PI engine (150 hp for the early cam and 124 hp for the later cam).

Bryan
 
In addition to the above, you also need the plenum, throttle bodies, metering unit and (even harder to find) the correct distributor. The throttle bodies are a bugger to balance.

You also have to provide provision for the fuel return, and no-one recommends using the original pump, so get a Bosch replacement.

Also remember that the PI system for the TR6 operates at very high pressure (about 60psi). If you get it wrong it will spew a LOT of fuel into the engine bay in very short order.

If you want the benefits of PI, and aren't desperate for originality look at Rick Pattens TBI setup - https://www.sidedrafttbi.com. You could also do it all yourself, using an aftermarket ecu (customefis or megasquirt spring to mind) but it is a lot more work.

One other option - the original PI system was 150hp. You can get that with a cam and triples for a lot less.

<edit> You have a 250. Then you will also need to get a late head.
 
What Alana says. The Lucas system is very temperamental and requires a lot of effort to keep it working as it should. The original fuel pump (Lucas), pumps fuel at 100psi and has a ceramic fuse in the engine bay, should something go wrong. I have read forum threads from the UK where the original PI system has been binned for carb conversions with greater horse power, upto 230hp. If you are looking for more ponies, maybe that is the way to go?
Regards
Craig
 
If you are interested in learning more about gaining performance, read Kas Kastner's three Performance Handbooks and Roger Williams "How to Improve Triumph TR5, 250 & 6.
 
Thanks for all the information, I am looking for a little more horsepower, nothing too radical, I had heard about the fuel pump issues, the vendor told me the later system, which is what he has, works with the American spec motor.

I realize it is far from state of the art, but I was interested in it as a period modification that would also bump the HP a good bit. As far as other mods I do want to look into that as well, do these drivetrains benefit from lightened flywheels?, I have a local shop that does that work quite reasonably.

I'll have to give it more thought and research.
 
If you do a search, you'll find hundreds of people that want to get more power out of their TR6!

The limit is the amount you want to spend.

If you are just looking for more power, rather than having a thing for the original PI system, then I'd say look at a cam, a header, a head skim, and triple carb conversion (look at Richard Good's site - https://www.goodparts.com - as a starting point). You can buy extra ZS carbs fairly readily, and the whole package will be less than the cost of the parts for PI, and will go in with a minimum of aggravation.

I don't think there will be too many dissenting opinions that this is an easier route to more power than trying to shoehorn the original PI system in there.

(Just so you know, I sold the one I had and went custom. It looked like a horrible install, and what I have in there is so much neater).

btw: A lightened flywheel lets it rev a little easier.

Good luck.
 
Look at Kastner's Triumph Preparation Handbook. You'll find that you can get to about 140 hp with just a new cam and higher compression. The dates on the dyno curves in the book are Dec. 1968 so I guess that makes them period mods!

Bryan
 
Hello all,

a lot of the myths still exist, I see.

I run a Triumph P.I saloon, still with the original Lucas fuel pump. I rarely ever touch any of it, and it just keeps soldiering on. (New air and fuel filters now and again)
I agree that over where you are P.I. parts are probably very rare but in the U.K they are easily sourced.

I notice someone mentioned 230 H.P., yes it's possible but requires a huge amount of money to get the engine to stay together at the revs that are needed for such power.
I would have thought that having a good head with about 9.5:1 compression, cam and most important a 6-3-1 exhaust manifold and just a pair of HS6 S.U's would give P.I spec power, maybe more without the need for special inlet manifolds etc.

Alec
 
piman said:
I would have thought that having a good head with about 9.5:1 compression, cam and most important a 6-3-1 exhaust manifold and just a pair of HS6 S.U's would give P.I spec power, maybe more without the need for special inlet manifolds etc.

Alec
Click to expand...

And, according to Kastner, you would have been right. He dyno'ed an engine with 10:1 compression, his cam, a GOOD extractor exhaust and the stock ZS carbs with the stock early style intake manifold and measured a peak of 150 hp. I believe 150 hp is the quoted PI number.

Of course, that doesn't have the bottom-end torque of the stock US-spec engine - but then I don't think the PI engine did either.

Bryan
 
I believe Kas also stated that the factory PI system was worthless, he could get more power with ZS carbs.
 
Hello Randall,

I thought that he did a lot of work with the injection system and has some very interesting modifications for it. These of course are not suitable for a road car. A large enough throat area is important with carburettors and I'd be surprised if two 1 1\2" Z.S. would equal the injection system, all other things being equal.

Originally the injection route was chosen by Triumph to meet American emission laws at that time, but they found that it failed and that the carburettors were able to meet it anyway which is why that is what you have over there. Unfortunately, for a sports car, it lost a lot of power over the U.K. specification injection cars.

Alec
 
piman said:
I thought that he did a lot of work with the injection system and has some very interesting modifications for it.
Click to expand...
I believe that is true. Kas doesn't seem like the kind of person to state what the development potential is, without trying it himself.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]I'd be surprised if two 1 1\2" Z.S. would equal the injection system, all other things being equal. [/QUOTE]Well, of course original was 1.75". And I'm just repeating what Kas wrote, I've not tried it myself.

Generally, though, any additional air flow capacity beyond "enough" is wasted and can actually hurt peak power.<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Unfortunately, for a sports car, it lost a lot of power over the U.K. specification injection cars.[/QUOTE]Also true. But most have said that the majority of the difference was the milder camshaft and lower compression, not PI vs ZS. Don't forget that the TR4A actually made more power than the US-spec TR6, with not only carbs but less displacement to boot.
 
Alec
you are doing well if all you need to do is change air and fuel filter on your injection system. My system requires constant maintenance from service to service (I don't touch it myself for fear of upsetting it). The Lucas pump probably works well in cold climates, but try putting up with one when it gets above 35C.
Maybe your fuel is also cleaner in the UK, but even with a replacement filter on mine a still get blocked injector heads now and then.
Regards
Craig
 
OK, I think I am talked out of it, I was partly taken in by the "wow factor" of opening up the hood and seeing the fuel injection system, but it sounds like more trouble than it is worth, sounds like skimming the head and a cam is the much more practical route.
 
For "wow factor" you might look into the triple ZS carb set up. I don't know if it gets you any hp but it looks really cool. Brosky and some others have it on their cars. It should be much simpler to install than the PI.

Bryan
 
Hello Craig,

certainly the ambient here is cooler than yours, but there are a couple of things you might like to look at such as what is the actual voltage at the pump with it running, as low voltage due to old connections and old cutout switch contacts can lose some power. Personally I have fitted a relay and heavy gauge wire to feed my pump. Make sure you don't let the tank level get too low if possible as the fuel return from the pressure regulator is heated somewhat.
I don't know what work you get done but there is very little adjustment on the system so what maintenance is necessary? Certainly the throttle balance can be awkward especially if it is worn, however that is easily overcome by opening the throttle wide, balance doesn't matter then :smile:
Actually i have fabricated a different linkage with a common rod and ball jointed links (as used on S.U. carburettors)

Alec
 
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