View Full Version : TR6 TR6 EFI - where do I start?

07-26-2006, 01:33 AM
Dear Experts,

I just blew my motor in my TR6. Number 1 piston split. I have the motor out of the car and ready to rebuild.

What I have.
Ex USA car converted to Right Hand Drive for Australia. Twin SU's and extractors.

What I want to do
Stage 1
Insert oxygen sensors on the extractors (2 sensors) to monitor rich / lean. This way I can sort out the SU's.
Fit crank sensor to harmonic balancer.

Stage 2
Replace manifold and fit EFI.

Where do I start and what issues should I be aware of to keep the car as desirable as possible? i.e. I don't want to replace the motor for a modern unit or go V8 etc.
Are PI manifolds available as I last saw one in a wreckers yard 10 years ago.
Is there an after market ECU I should use that is the "Triumph one" to keep it conforming to the norm?
Are Cams available and what do I need keeping in mind it is a daily driver?


07-26-2006, 06:31 AM
I think the best course of action at this time would be to acquire a copy of this book (How to Improve the TR6 by Roger Williams). (https://www.pitstop.net.au/pitstop/page/marques_triumph_tr2_tr8/12699.html) I don't have this one, but have the one for the TR2-4, and in it he goes though the fitment of various types of fuel injection setups. I'm sure he does the same in the TR6 book.

07-26-2006, 07:47 AM
What sort of EFI do you want?
Or put it another way how much do you want to spend?

You can do anything from a relatively simple throttle body injection setup to a full-on smpi job. Its a question of time and $.

Think also about why you are doing this.

Are you doing this for more power? If so then this is not the most cost effective solution.



If you can answer these questions then I'm sure you'll get a much more detailed response, tailored to your actual needs.

07-26-2006, 08:45 AM
One word - Megasquirt

You can see what can be accomplished via Megasquirt at:
I have included all of the VE and spark advance maps that I use. If you have any questions please feel free to contact me at:


Hope this helps

07-26-2006, 03:18 PM
Also take a look at www.sdsefi.com. (https://www.sdsefi.com.) Simpler than MS, easier to tune and maybe a bit limited in comparison. If you are going to build a relatively stock engine, it should work well. It costs more if you don't factor in time to build or de-bug the MS.

With either of these the major challenge and/or cost will be in the intake manifold fab.

07-26-2006, 04:14 PM
Hi Dave,

I'm certainly no expert, but find this topic very intriguing and some good suggestions have already been given. I agree your first step will be to do lots of research, even on a local level to see if there are specialists in your area that might offer help, parts that might be available, others who have made similar conversions and might provide some guidance, etc.

I know very little about the "universal" application EFI systems mentioned, but am always a little skeptical of these. Still, they are certainly well worth exploring and considering.

In Roger William's book you will find several other EFI options discussed.

First, a section is devoted to converting to an original Lucas PI system and includes some ideas how to improve upon that system. There are advantages to this, such as that it is a proven system. I'm not talking about reliability, just that all the myriad system details were worked out for you, many years ago by the factory engineers. The years since have shown up the weaknesses of that system and ways to correct them. Disadvantages would be that some parts might be very hard to find and/or expensive. Also, later forms of EFI might be more advanced and could offer better tuning potential and higher general reliability.

Roger also suggests how you might cobble together an EFI system from used parts, and lists some of those parts and the specific cars they can be found on. In this case, I think anyone doing it would need some level of knowledge and expertise, or be willing to research and learn it, before attempting! Alternatively, a good local shop with a lot of EFI skills and knowledge might help.

The third method Roger covers is to install a kit that's already been sorted out for you, specific to the car. www.revingtontr.com (https://www.revingtontr.com) in England is probably the premier source today, selling Luminition and Webcon (weber carbs manufacturer) EFI system kits carefully tuned for the different TR models. Both are pretty expensive. The Luminition is just a little cheaper but a little less sophisticated, too.

These complex kits are the top end of the price scale, of course. But going the other routes might prove to be false economy, if you end up doing a lot of expensive testing and sorting before getting it "right" (or worse, never really getting results that satisfy you!). What appeared cheaper initially could end up actually costing more.

You will need to do other prep work on the engine to bring it up to EFI standards, if you expect EFI to perform well. A different cam is definitely called for and, I think, different compression ratio is used (which might need to be modified from the original specs to accomodate changes in today's fuels and/or regional fuel differences).

Also, the EFI (PI) cars used a different cylinder head than the USA cars. I bet the US head could be used in some instances, perhaps with some modifications. But, for example, I don't think the Lucas PI system can bolt up directly to it. A replacement PI head might make more sense. Depends upon availability and cost. Carefully research other factors, such as if there is a different head gasket and/or valves, etc. used with PI. Even the exhaust might be different. I'm certain the fuel tank arrangement is different from the carbureted models.

All in all, I think it's great you are considering this and I'm not trying to dissuade you in any way. In fact, I'd like to try a similar conversion too, some day!

In general, William's take on EFI is that anyone considering performance upgrades to their TR should try to get a ride in an EFI converted car before commmiting time and money to other routes of improvement (such as dual Weber carbs). He feels strongly that EFI is a super way to bring the cars up-to-date in terms of performance and "fun", and highly recommends EFI for serious consideration.

Please keep us posted!


07-26-2006, 04:59 PM
"Also, the EFI (PI) cars used a different cylinder head than the USA cars"
I suspect the heads in question are the ones on the TR250 and early TR6. (up to '72 ?). The space between the intake ports on the early US heads was less than on the later heads. If you decide to go with the Lucas injection you should confirm the head requirements. Chris Witor in the UK is an expert on Triumph heads. You may want to visit his site. https://www.chriswitor.com/

07-26-2006, 05:41 PM
you need a 73 and on head.
i know because i actually sold the setup i bought about 7 months ago on ebay. decided to go with a custom manifold.

07-26-2006, 07:15 PM
I just found Mega Squirt the other day and impressed by what it offers. I am currently building a Locost with Oct 2005 Ford Focus Duratec motor (same block as MX5) with 4,085 km on the clock. I went this way as the SU's drive me mad or more importantly the variation in fuel drives me mad.

Fuel is crap. 98 octane isn't always 98, as the motor runs on when I use 91 and sometimes a tank full of 98 runs on. I bet this shagged the motor when it runs on backwards. I leaned it up a bit too much and this solved the run on but then the rattle started. I pulled it out before it did too much damage. I really want to overcome the fuel issue.

Oxygen sensors are a start. "To measure is to know." From there the natural progression is EFI. Can I get either original or after market PI or EFI manifolds?


07-26-2006, 07:47 PM
First off - you cant fit the crank trigger to the harmonic balancer. You have to fit it to the fan extension. Or better yet, get an electric fan and use a fan eliminator and fit it to that.

Second - you'll find it hard to get an original PI manifold. This means you have two alternative choices - buy one of the aftermarket options (check out TWM as an example, they don't quote the price online, but I swapped emails with them last year and they quoted $4200 US) or have one made. Given the cost of the off the shelf options I'd recommend having one made. Locally.

Find a shop that makes manifolds for japanese cars and be prepared to write a big check.

This of course presupposes you cant make one yourself. If you can TIG and have a bit of time then you are golden.

After that you get into ECUs. You can go from Motec/Autronic all the way down to Megasquirt. Pick one that suits both your budget and the amount of time you want to invest in it.

To get decent power you'll need to work over the engine. A cam and some porting at the very least.

There are other simpler options if you want a 'kit' - do a search for TBI/TR6 for example. There are also at least two UK ones also that were covered previously.

Good luck whatever you decide to do.

07-27-2006, 06:38 AM
On the bright side I pulled the head off and number 1 piston has a chunk out of it. I can only see the slightest mark on the bore and as such a light hone will clean it up. This means i have very close to original size bores. I can see all of the hone marks from 10 years ago and it has done around 11,000 miles since then. The valves look great but this car was laid up for a year or two and was a little smoky when i got it going again. I assume the rings were to blaim but after a chemical clean out and a hard run all came good.

I am scared by the manafold prices. Kicking myself for not getting the OEM unit 10 years ago. As for the sensor and spocket / notched wheel i had planned to turn a bit off the back of the pully and bung it on there. Should I rethink this?

There is a piston manufacturer in South Australia who sell globally.
Can anyone recommend them or another company or another car OEM piston that just happen to fit?

BTW has anyone got or know of a PI manafold for sale? (hope this is ok within the rules of the forum to ask.)

Thanks to the repliers too. Great info and it has helped a lot.


07-27-2006, 11:31 AM
I have recently read on another forum that the PI manifold is not the way to go for EFI. Evidently the mechanical injection of the Lucas PI and the needs for EFI are quite different and the butterflies/chokes in the PI manifolds are too large for proper EFI calibration. Really hurting the driveability and tuneability of EFI.

I plan to investigate this some more as I was hoping to use the PI manifold set up that I have as a basis for an EFI conversion. That might now have to be re-thought.


07-27-2006, 06:31 PM
Thats why I sold mine and went custom...
If you can TIG have a look at this:

07-30-2006, 06:53 AM
Great Link. Do you have a picture if the custom deal? I was keen on the PI manifold but removing the butterfly plugging the bushes and hoped to add the air control to the Triumph main air intake of the larger common tube.


07-30-2006, 11:45 PM
where abouts do you live? Here in Perth there are a couple of dedicated Triumph mechanics. They will be able to locate the parts and advise on standard Lucas injection conversions. I'm sure there are a few salvagable systems around that the mechanics can lay their hands on.

07-31-2006, 01:35 AM
I am in Melbourne Craig. I last saw a PI in a wrecker 10+ years ago. To this day I cannot believe I didn't take the manifold. I don't visit the wreckers much.

Back then I did get a J type O/Drive. Looking at the effort to convert now as the old box is out. (graft the J type to TR6 box) I got rear axles out of an auto too as they will not have suffered the same stress as a manual.

AU$700 (USD$500) for JP Pistons with improved rings and oil control. Got the old pistons out and found every OEM ring broken again. Low km's but happy to see the hone marks in the bores. Re-honed bores to be sure and still about 1 - 2 thou inch over original.

Can you ask around on my behalf please craig so I can get an idea on PI manifold pricing. It has be a big week of outgoings. I feel the O2 sensors will tell me a lot but if the price is low I may get it to do the mod later. It has also been suggested making a few manifolds - cast and machined to suit. I like the idea of the OEM set up though.

Does anyone know if it has been done?


07-31-2006, 01:57 PM
Hi Dave,

You might want to have a look at this : https://topshamautoparts.com/tr6/tbi.htm

NFI, but it looks like a economical approach and seems to have good results. I'm considering going with it myself

07-31-2006, 04:06 PM
Dave - this is my one.
It is designed for a single TB as you see so I can supercharge the engine.

07-31-2006, 08:05 PM
Alan, who fabbed that up for you and do you think they would do more?

07-31-2006, 08:11 PM
I'm sure they would - its $$$$ expensive though. It was done by a guy who specialises in this sort of thing, but for 4-pot imports.

Also I had to get it anodized and laser etched myself afterwards.

If you want more info pm me.

07-31-2006, 11:15 PM
I spoke to my mechanic this morning and he can get his hands on a TR6 head, manifold and mechanical metering off an original injection TR6 within a week for approx $1,000, fully reconditioned.
You will possibly need a cam upgrade for USA imports. He has a worked TR5 cam to suit for around $450. Apparently the cam in USA models is not upto spec for injection performance. You will also have freight and fitting costs your end.
If this is within your budget, let me know and I can pass on the mechanic's details.

08-01-2006, 07:38 AM
If you are going that way, have a read of these:

08-01-2006, 12:42 PM
I'm sure they would - its $$$$ expensive though. It was done by a guy who specialises in this sort of thing, but for 4-pot imports.

Also I had to get it anodized and laser etched myself afterwards.

If you want more info pm me.

[/ QUOTE ]

I should have paid closer attention during your initial write ups. You have a PM coming.


08-01-2006, 07:05 PM
In no order of reply. I have the bits for the head but a couple of the rocker arms are worn. I have been told they can be ground and rehardened. I need to find some more as this could be cheaper. The cam is interesting. I will try locally first.
That TB is a ripper. Do you have drawings? Did it work? I am amazed by the work some folk do. Top effort.

08-01-2006, 07:33 PM
For more power you are going to have to change the cam. Whether you do PI or no.

08-06-2006, 07:13 AM
The cam is a good point. What is available? Do you have any specs like degs to open and close inlet and exhaust? My cam is going to be either reground std or fit it is not too expencive I will make it mild rather than hot.


Please post your cam success and failure stories.

08-06-2006, 03:50 PM
Hi Dave,

Oh geez! There are literally dozens of cam grinds possible! And probably just as many or even more opinions about what makes for a good cam.

First of all, it is usually no more expensive to have a cam ground to be moderately more aggressive, than it is to have it ground to stock profile. The same work needs to be done, either way. It is only more radical cams that get more work at higher cost.

And, there are many aspects that can be changed to tune a cam's performance. Often degrees of duration or duration plus lift are used as a key point of comparision, although there are many other factors (overlap, symetry, lift at the lobe, lift at the valve, timing and lobe profile are some that come immediately to mind).

I would call a 270-290 degree cam a moderate improvement. I don't know what the original P.I. cars used, would suspect it was relatively mild since most of Triumph's cams were: best guess, about 260 degrees. (Carbureted cars seemed to be fitted with about 245 degree cams).

Once you get up over 290 or 300 degrees, it's more of a full race cam and has to have more work done, thus costs more, and will lose some street drivability because it moves the effective rpm range much higher (and reduces low end torque). Of course, once you get into aggressive, high rev cams, that means many other engine mods will be needed to keep it all together at those higher rpms.

Many people seem to over-specify their cams, but it sounds like you are aware of this potential pitfall.

In terms of lift you'll see some cams specs stated at the valve, others at the lobe. The rocker arms give a ratio that moves the valve farther than the lobe lifts the follower. Usually, when a cam grinder states the dimension at the valve, this is using a relatively common and mild 1.5:1 ratio (but this is a good thing to ask a grinder about). Be aware that stock Triumph rockers are really more like 1.45:1 ratio, so are conservative. That means a little less valve opening (and thus a little less gas flow). But, it's "safe", I suppose. At the other end of things, some aftermarket roller rockers provide 1.6:1 or even 1.7:1 ratios, which can lead to other problems and really change factors after the cam grind, make for unpredictable results (and sometimes broken valve springs and other nasty problems).

The point is, usually you can convert back and forth between lift at the valve and lift at the cam lobe using a 1.5:1 ratio. That's what many cam grinders use. This is often necessary trying to get apples-to-apples comparisons between cams, I'm afraid.

You'll have to do some research, chat with some folks and match the cam to other work you are doing or have already done on the engine.

A brand new cam, freshly ground on a blank, is preferable in some respects, but is a lot more expensive. The main difference is that whenever a cam is reground, there is some loss of the lower part of the lobes, too, necessary to establish the new profile. Because of this, new, slightly longer pushrods might be needed as well. (But that might be offset a little or a lot if the cylinder head is skimmed to straighten it up, or if it's milled significantly to increase compression.)

When changing a cam, I'd usually plan on new lifters (cam followers), pushrods, and possibly valve springs, as well. In your car, you will likely want to install cam bearings (just a matter of adding Spitfire bearings in TR6/GT6 motors), since the cam is probably now running directly in the block. Also, a freshly reground cam usually needs to be hardened (nitriding or similar), or it simply won't survive past the first ten minutes of running. When it's installed, use lots of cam lube to help it survive, too.

With significantly more aggressive cams and higher rpms, stronger springs are often used to prevent "bounce" or "float", where the cam follower doesn't stay solidly planted on the lobe, messing up valve timing. However, with stronger springs comes faster lobe wear. Ask around what's needed. I can only tell you that stock springs are pretty good on the 4-cyl. TRs, these engines don't tend to have problems with bounce of float, so at most only a slight spring rate increase is needed in most circumstances. It might be different for the 6-cyl. TRs, though.

To start finding out more about cams, check out all the usual suppliers and info they have on their websites. One place to start is Elgin Cams. They have lot's of cam info online. https://www.elgincams.com/

Kent is a big manufacturer of LBC tuning parts, and might have a website. I don't have a URL for it.

I know there are some other websites with lots of info very specific to TR6, but don't know how much info they offer about cams for P.I. applications.

Finally, with an improved cam, you might want to fit an adjustable cam sprocket up front, so you can really dial in the valve timing as close as possible and get the best out of the cam. These sprockets are pretty widely for the 6-cylinder TR motor.

Hope this helps!