Stag Engine PI and manifolds

[mikew]

Quoted from andy thompson

What  Stags desperately need is a decent inlet manifold and dare I say injection ? The standard set up serves only one purpose I can see and that is to fit under the bonnet

Thats my other long term project. I have made up a new "dummy" set of inlet manifolds - 2 so they can be individually bolted to the heads, one has the thermostat housing, with the other manifold connected via a hose - this means less sealing problems in the V (even with skimmed heads) you will even be able to dowl them to the heads to get port matching correct.

I am going for the single plenum, throttle body approach (like rover v - I am having some difficulty resolving the "adjustment" of the second manifold into the plenum but this will get sorted when time allows.

It should all be done in 3 castings, 2 manifolds and the plenum, with a removable flat alloy top plate on the plenum. Room in the plenum for standard intake trumpets.

Use megasquirt etc etc

Should improve fuel economy, hot starting etc etc

But what would be the demand?

mike

[iani]

I imagine the demand would depend on the cost to a degree, do you have a view as to what the final cost would be once all other parts were bought?

Ian

[harvey]

I know someone that built a fuel injection system for a Stag as a project and that was about 20-25 years ago, from what I remember he just made and modified what he needed, but I can't remember the details, and technology has moved on such that what he did would have been rendered obsolete by now, but it was pretty clever at the time nevertheless. It worked as it should, but he never made his fortune from it. It must be easier now with the advent of the mappable EFI systems.
He went on to work on Formula 1 powerboat engines, and the Toyota Le Mans team.

[Jason]

The factory played with Lucas Mk2 mechanical injection - http://triumphmuseum.blogspot.com/2009/01/stag-v8-lucas-petrol-injection-inlet.html would look great with some ram pipes going straight up out the bonnet!! 😎

[Richard B]

Quoted from mikew

Thats my other long term project. I have made up a new "dummy" set of inlet manifolds - 2 so they can be individually bolted to the heads, one has the thermostat housing, with the other manifold connected via a hose - this means less sealing problems in the V (even with skimmed heads) you will even be able to dowl them to the heads to get port matching correct.

Interested, depending on price. Been an idea on the back boiler for a while...

The PI manifold does not include the water ways.

[Nick Jones]

This has been done by a gent in either Denmark or Sweden who modified the  carb manifold fairly extensively and used Megasquirt.

I found him via the Megasquirt "success stories" before I'd even started mine (5 + years ago) and it was there for a while as I looked at it several times.  Of course I can't find it now I want want it 🙁  Seem to remember he claimed huge torque and vastly improved fuel economy from an otherwise standard but carefully built engine.  If I had a Stag with original V8 I would do this, and probably lpg it at the same time.

Nick

[Richard B]

I like Mike's idea to split the manifold into two. Resolves the problems of sealing the waterways on both heads.

There must be a better way to deal with those Stag waterways! 🤔

[mikew]

Collective reply to the above, sorry about this but I am busy in Edinburgh at the moment.

Costs:-

Megasquirt, and the injectors, sensors, throttle body etc about

[Nick Jones]

Sounds ok to me.  I'd imagine the main cost would be the casting patterns and tooling up for the machining.  I don't have any kind of feel for what that might be.  Numbers produced will obviously have a huge effect on total manufacturing cost but I reckon that anything up to

[Richard B]

Quoted from mikew

Castings ??? not as much as you think once the patterns are done, but they will need machining as well.

Well I'm only concerned about the cost of the casting's (preferably machined) at present.

This would be yet another of my 'projects'. The megasquirt etc would be acquired later. I've always thought the Stag Induction & Extraction systems needed improvement.

[StagNL]

Out of curiosity, has anyone made up a better manifold for use with the standard Stomberg carbs?  If there is that much to gain from a better manifold I would have thought that it might have already been attemped.  I've seen photos of different project Stag PI manifolds that were custom built out of alloy tubing and plates, but nothing as yet for carbs.

Personally I'd prefer a setup that uses the carbs and LPG rather than pay double the price for both PI and LPG.
LPG systems in this country (NL) generally must be installed by certified businesses which often drives the price up and I don't have a money tree in the garden.

Julian

[Richard B]

EFI should improve the power & economy of a V8.

and I can't afford a V8 PI Metering Unit.

[andy thompson]

Definitely interested in finished manifolds....

[mikew]

Quoted from Nick Jones

Sounds ok to me.  I'd imagine the main cost would be the casting patterns and tooling up for the machining.  I don't have any kind of feel for what that might be.  Numbers produced will obviously have a huge effect on total manufacturing cost but I reckon that anything up to

• Quote

[mikew]

Quoted from StagNL

Personally I'd prefer a setup that uses the carbs and LPG rather than pay double the price for both PI and LPG.
LPG systems in this country (NL) generally must be installed by certified businesses which often drives the price up and I don't have a money tree in the garden.

Julian

Gas systems here have to be certified, but you can do the work yourself and get it inspected and certified.

If you are only really after LPG, why not use the old gas mixer type - this works reasonably with carbs and could be made to fit your manifold, as it would sit as a mixer ring just under the carbs.

My intention was to allow the possibility of "injection" lpg, which works as well as efi

mike

[mikew]

Quoted from Richard B

EFI should improve the power & economy of a V8.

and I can't afford a V8 PI Metering Unit.

why not ?

they are only used on Italian exotica and race engines ?

EFI on the 6 pot unit takes fuel economy from 25mpg to 35/40 mpg so its a significant improvement, should be similar on the V8

mike

[Richard B]

Quoted from mikew

why not ?

they are only used on Italian exotica and race engines ?

Last quote I heard was about

[tonypy2]

Definitely interested in efi manifold(s), I've already converted my Jag V8 to lpg and would be very keen to do this to the stag.  Fully sequential lpg injection kits are much better than the mixer types, I can't detect any difference in power on lpg.  does the megasquirt operate on the OBD II system, if so it would be dead easy to fit the gas kit.  Cost me about

[StagNL]

Quoted from mikew

Gas systems here have to be certified, but you can do the work yourself and get it inspected and certified.

If you are only really after LPG, why not use the old gas mixer type - this works reasonably with carbs and could be made to fit your manifold, as it would sit as a mixer ring just under the carbs.

My intention was to allow the possibility of "injection" lpg, which works as well as efi

mike

I've briefly looked into the mixer ring system and it seems a simple enough approach.  What I really am looking for is a way to improve the running cost as the price of LPG is way lower than petrol here, plus it is widely available.
If I were to fit injection gear (at a price) I would still not reap the benefits of low fuel prices unless I also install LPG.

My line of thought is that if there is an advantage to be gained by good manifolds, why not use them with carbs and LPG?  I guess the biggest problem is space.

Very simplified math:
Injection gear = 2.500-3000 euros
LPG gear = 2.500-3000 euros
Injection and LPG - 5000-6000 euros

Performance is something I hold dear and if possible would like to increase that too, but the price of fuel dictates my choice toward lower cost LPG.  I simply don't have the reserves to shell out on a combined EFI LPG setup.  (or maybe I just don't want to pay so much)
Again, simple math tells that an LPG system will repay itself in 3-4 yrs.  EFI on its own cannot come close to that.

I reckon my best bet is to go talk to the LPG installation guys down the road from my work.  A good chat with them on what is possible might be enlightening.

Julian

[Nick Jones]

Megasquirt is not OBDII or even OBDI.  ONly worth using Megasquirt if the car is not already injected as it can then perform both the Petrol and LPG functions (dual maps) as well as the ignition control if wanted.

On a car that is elready electronically injected it makes more sense to use the "piggy back" ECUs that the LPG folks supply.

Nick

[Flying Farmer]

I have built several efi stag engines over the last 10 years using a variety of inlet manifolds, some modified stag and lastly scratch built from steel tube to suit a Rover plenum. All my systems have used Rover vitesse flap type injection as you can use the standard ECU. It may or may not be relavent but all my engines have used 4:2:1 exhaust manifolds in one and a half inch tube copied from the rover V8 but rearranged to suit the different firing order.
On a low compression 8.5:1 engine (mk 2 with dished pistons) I am getting about 165bhp at 5250 rpm using a modified stag manifold.
I then built a high compression 10.1:1 engine with fast road cams and tried a stag manifold with the middle opened out.This made 175bhp at 5500 rpm but had a disapointing lack of bottom end torque.
Next was a steel tube manifold to link to a Vitesse plenum. This has external waterways taken from the water transfer housings. This one made 172bhp at 5500rpm but had hugely better torque at low revs and made 49bhp at 1500rpm against 34bhp at 1500rpm for the stag manifold
The final set up was arrived at after reading that rover V8s needed the plenum trumpets shortening to make them rev. I shortened mine by 1 to 1.5 inches to make them all the same length and also split them down the side and bashed in a big socket to flare them out before welding a piece into the resulting triangular hole.
Next dyno run was a spectacular improvement, 201bhp at 5500rpm rising to 207bhp at 6000rpm and it was still making 206bhp on the limiter at 6500rpm. Torque was better all the way through the rev range and best of all fuel consumption normally runs at high 20's though I did p*ss off a lot of TR owners when we did an economy run and I won with 35mpg (the engine is in a TR5)
To conclude, do away with the stag manifold but watch inlet tract length very carefully as this is where sucsess or failure lie.
PS complete injection system cost me

[anthropoidape]

For EFI, I would not look just at megasquirt, I would look first at dropping in working EFI from a similar displacement V8 engine... BMW, Rover, etc. Early 90s EFI would probably be the easiest, as more ECUs then were standalone and didn't require BCMs and other extraneous bits. All you'd have to worry about is the manifold (which admittedly is a fair bit of worry).

If you are going to install LPG, installing EFI is a complete waste of time anyway. One or the other.

I assume it is unacceptable to mention that a complete engine and gearbox swap would give much better results for both performance and economy than anything you could do with the Stag engine.

[mikew]

Quoted from anthropoidape

For EFI, I would not look just at megasquirt, I would look first at dropping in working EFI from a similar displacement V8 engine... BMW, Rover, etc. Early 90s EFI would probably be the easiest, as more ECUs then were standalone and didn't require BCMs and other extraneous bits. All you'd have to worry about is the manifold (which admittedly is a fair bit of worry).

If you are going to install LPG, installing EFI is a complete waste of time anyway. One or the other.

I assume it is unacceptable to mention that a complete engine and gearbox swap would give much better results for both performance and economy than anything you could do with the Stag engine.

Megasquirt ecu's, and enerald, omex etc, are programmable and can be mapped exactly to your engine, an old ecu from another car will probably not be correct but a compromise.

The point about efi and lpg is the availability of lpg. you certainly cannot get lpg every where, probably only 1 in 50 filling stations - I don't think you could possibly do the rbrr with lpg.

And yes, it is pointless swapping for another engine - particularly from my own view point with a ff system on the bw35 box.

mike

[mikew]

Quoted from Flying Farmer

To conclude, do away with the stag manifold but watch inlet tract length very carefully as this is where sucsess or failure lie.
PS complete injection system cost me

• Quote

[Richard B]

Quoted from Flying Farmer

The final set up was arrived at after reading that rover V8s needed the plenum trumpets shortening to make them rev. I shortened mine by 1 to 1.5 inches to make them all the same length and also split them down the side and bashed in a big socket to flare them out before welding a piece into the resulting triangular hole.
Torque was better all the way through the rev range and best of all fuel consumption normally runs at high 20's though I did p*ss off a lot of TR owners when we did an economy run and I won with 35mpg (the engine is in a TR5)

Could we have some pictures please?