Building "Thor"

[Storer]

eliot said:

Max_Torque said:

That's why you want one or two normal but large throttle bodies on a large normal plenum.

This is going back a bit, but I think Charlie originally had a throttle at each end of a single plenum (Omega 2.5 v6 items IRRC):



Are you in touch with Charlie?

Edited by eliot on Saturday 23 August 09:12

Edited by eliot on Saturday 23 August 09:13

Oh yes. Charlie has been very helpful and supportive.

His opinion is that if you want to do something, and do it your own way, then it doesn't matter what others think. If it doesn't work, then change it.

It will be interesting to see how he organises the intake when he fits his supercharger.


Paul

BTW. He thinks the M3 bodies will be fine!

[ARAF]

Storer said:

BTW. He thinks the M3 bodies will be fine!

[anonymous-user]

Storer said:

These M3 throttle bodies are very simple. The actuator shaft is mounted in bearings on the bodies and each butterfly is connected to the shaft with a ball and socket rod.
Each has an adjustable stop on the butterfly and it's own spring return.

The two shafts will be linked together again with a ball and socket shaft. All very simple and mechanical (none of the mystical electronic wizardry!) and all controlled by a simple throttle cable from the loud pedal.


Paul

Indeed, but by the time you have 12 of them, all interlinked, on long flexi and vibrating shafts, that need to be able to take into account the expansion of the engine structure you can easily run into problems. Then there is the issue of being forced (unless you are clever) to use throttle based load determination, your low speed driveability will suffer enormously. Then, you have to adjust 12 idle stops and try to ensure all the throttles open the same amount at the same time (otherwise AFR distribution will be poor) and again driveability suffers.

If you wanted to make more torque/power, then you would need a much longer inlet tract (with this engine being a very "slow speed" design) and without a plenum you loose any hope of secondary volume tuning etc. With the super short, throttle by each valve approach, the transition from idle torque (ie torque = friction) to drive torque (ie net positive flywheel torque) will be extremely sudden and likely to be very changable with things like engine temp, air temp etc.


but as you say, it's good to do your own thing.

[RoverP6B]

What, the Meteor SD1 is getting a blower? Surely not the proper Merlin blower?

[LewG]

Hi Paul,
Top work! Someone recently posted about Megasquirt injection and through our military vehicle hobby it reminded me of the guys at REME Bordon who run the vehicle collection. They have a Conqueror armoured recovery vehicle with much the same Meteor as a Centurion tank except that it's an M120 variant with around 800hp as opposed to the original 650. I'm not sure if these were fuel injected instead but I remember the Bordon guys having lots of running problems with their preserved example. In the end they put a Megasquirt system on and I believe it's been successful ever since. So if you decide to go down that route there may be some knowledge to be gained from them.

[Storer]

markh1 said:

After reading through this I had to post this short film from 4oD.....

http://www.channel4.com/programmes/guy-martins-pas...

I love Guy's attitude to life. He is way braver than me but he does like to 'have a go' which I applaud.

Lord knows what his running Merlin cost!! I recon a nice running Meteor on a chassis is £10k all day, so a Merlin must be 4 to 5 times that at least.


Paul

[Storer]

LewG said:

Hi Paul,
Top work! Someone recently posted about Megasquirt injection and through our military vehicle hobby it reminded me of the guys at REME Bordon who run the vehicle collection. They have a Conqueror armoured recovery vehicle with much the same Meteor as a Centurion tank except that it's an M120 variant with around 800hp as opposed to the original 650. I'm not sure if these were fuel injected instead but I remember the Bordon guys having lots of running problems with their preserved example. In the end they put a Megasquirt system on and I believe it's been successful ever since. So if you decide to go down that route there may be some knowledge to be gained from them.

I know nothing about Megasquirt so will have to do a bit of Googleing.

Don't want more power, just an engine that runs reliably.


Paul

[Storer]

Storer said:

markh1 said:

After reading through this I had to post this short film from 4oD.....

http://www.channel4.com/programmes/guy-martins-pas...

I love Guy's attitude to life. He is way braver than me but he does like to 'have a go' which I applaud.

Lord knows what his running Merlin cost!! I recon a nice running Meteor on a chassis is £10k all day, so a Merlin must be 4 to 5 times that at least.


Paul

I was off by quite a bit as I found this add.

http://www.prewarcar.com/index.php?option=com_cara...

Paul

[Steve_D]

Storer said:

I know nothing about Megasquirt so will have to do a bit of Googleing.

Don't want more power, just an engine that runs reliably.


Paul

I found this firing order
1A, 6B, 4A, 3B, 2A, 5B.
6A, 1B, 3A, 4B, 5A, 2B.

I believe this is indicating the first firing in the sequence will be cylinders 1A and 6A together.

If so then you would need to set MegaSquirt up with 2 Ford EDIS6 units and 2 Ford 6 post coil packs.
This would run the engine in what is known as wasted spark. In your case it would fire 4 cylinders at the same time only 2 of those will be on the exhaust stroke so will not do anything.

There are plenty of places to buy all the MegaSquirt and EDIS stuff but Triggerwheels.com is probably the easiest. They may be keen to assist so they can mention your engine on their web site.

One of the sensors for MS is the manifold vacuum sensor which is why Max has been suggesting the use of a plenum rather than individual throttle bodies. MS can be controlled from a throttle position sensor but is not ideal.

Steve

[Storer]

Hi Steve

Thanks for the post. I have still to look into the control of the injectors/ignition.

Would the Megasquirt be able to support 24 spark plugs??? I assume you can't fire 2 plugs from one distributor outlet due to voltage drop. The two plugs per cylinder fire at a slightly different position relative to TDC to enable a complete burn.

I know that Charlie uses an Omex system on his engine so I do have a choice of systems.


aul

[Steve_D]

Storer said:

Hi Steve

Thanks for the post. I have still to look into the control of the injectors/ignition.

Would the Megasquirt be able to support 24 spark plugs??? I assume you can't fire 2 plugs from one distributor outlet due to voltage drop. The two plugs per cylinder fire at a slightly different position relative to TDC to enable a complete burn.

I know that Charlie uses an Omex system on his engine so I do have a choice of systems.


aul

I assume it has 2 dizzys in order to get the two plugs per cylinder firing slightly off each other. Do you know what the difference in timing is and does that difference remain the same across the rev range.

With the low revs the engine runs at I suspect you may be better running sequential injection which I don't believe MegaSquirt can handle but I stand to be corrected.

Steve

[Fastdruid]

Steve_D said:

I assume it has 2 dizzys in order to get the two plugs per cylinder firing slightly off each other. Do you know what the difference in timing is and does that difference remain the same across the rev range.

With the low revs the engine runs at I suspect you may be better running sequential injection which I don't believe MegaSquirt can handle but I stand to be corrected.

Steve

It can but you need MS3X plus some extra modifications, as stock (with MS3X) it only does sequential for 8 cylinders.

Source: http://www.msextra.com/doc/ms3/v10_v12.html

[anonymous-user]

Storer said:

Hi Steve



Would the Megasquirt be able to support 24 spark plugs???

Does the engine actually "need" 2 park plugs per cylinder? i.e. are they there for performance reasons (possibly, given the big bore / low speed nature of the engine i.e. slow burn = detonation limited) or for reliability reasons (you don't want your plane or tank "misfiring" when some one else is firing at you!!

I bet you could blank half the plugs, run with a modern high voltage ignition system, using wide gaps, and possibly a multi-strike strategy on the remaining 12 plugs and it would be fine.......

[Steve_D]

Fastdruid said:

Steve_D said:

I assume it has 2 dizzys in order to get the two plugs per cylinder firing slightly off each other. Do you know what the difference in timing is and does that difference remain the same across the rev range.

With the low revs the engine runs at I suspect you may be better running sequential injection which I don't believe MegaSquirt can handle but I stand to be corrected.

Steve

It can but you need MS3X plus some extra modifications, as stock (with MS3X) it only does sequential for 8 cylinders.

Source: http://www.msextra.com/doc/ms3/v10_v12.html

The 8 cylinder restriction I don't believe will apply if the 12 cylinders are actually not running as 12 sequentially but as two sets of 6 sequential.

If all 24 plugs have to fire you could perhaps run the first set and fuelling from MS3X then run a megajolt just for the remaining plugs.

Steve

[ivanhoew]

if its on magneto's I would run the mags ,and use ms for the fueling .

mags have a long spark duration ,which is nice for a big cylinder.

[anonymous-user]

But what you want for decent driveability, good performance and economy (relatively ;-) is mapped ignition!

Looking at pics of the meteor/merlin combustion chamber, it seems the plugs are diametrically opposed across the width of the chamber, without any obvious squish zones etc. Assuming both plugs actually ignite the mixture, then the burn rate is roughly twice what you would get from a single plug (because you have two flame fronts). However, the engine is such "slow speed" design, burn rate is really only going to improve fuel economy rather than add (much) absolute performance.

The question is does the charge dynamics actually allow both plugs to light the charge evenly and symmetrically. Highly doubtful looking at the piston / port / valve design. So i'm going to suggest the twin plugs are an "aero" thing, designed for reliability rather than performance. (on the highly boosted and faster rev-ing Merlins, a fast burn is definitely going to help increase the engines detonation resistance, moving MBT closer to TDC. but on the Meteor? Unlikely it will make much difference)

I suspect that adding much much better control of absolute ignition angle and fuel mixture with a modern EMS system will render the "dual plug" architecture un-necessary for this engine!

[chuntington101]

I thought the dual plug thing was as a backup in case of a system failure. I thought that pretty much all system had some form of redundancy.

[eliot]

Dug out this old post of Phil Ringwood supplying a wasted setup for a meteor, this is on the very old(now) msextra code.
http://www.msextra.com/forums/viewtopic.php?t=2462...
He's on this forum, usally lurking around the v8/tvr sections and has his own website. He wrote many of the early enhancements to megasquirt and continues to develop and sell products to this day.

[Storer]

I am glad to see that this thread is generating some exercise for other peoples grey cells. Part of the reason for building this 'special' is to give others pleasure/a sense of involvement, so please keep the comment coming.

As far as I am aware the differential between the two plugs firing stays the same through the rev range. I am sure the twin plug arrangement is primarily a left over from the aero design but it does help achieve a complete burn (remember, each cylinder is 2.25 litres so a long way between plugs which are opposite each other). The planes didn't rev much higher though.

I like the 'theatre' of twin plugs and I will probably use the two distributors to feed the plugs but then use technology to manage when they fire.

Starting is an issue due to the low 'energy' in the spark from the magnetos at low revs and this is aided by a switchable booster coil which fires a 'boost' to all spark plugs on one of the distributors. Modern plugs will help but may not be sufficient to avoid this issue.

As you may already have gathered I am not very tech savvy. I need to be able to see how something works to be able to understand it so I tend to take the proven route from people with experience when it comes to this new fangled electricity stuff. The suck, squeeze and blow bits I can sort. It's the 'making it bang' bit I will probably use others experience for!

Keep the comments rolling.


Paul

[Fastdruid]

I think I'd lose the magnetos but keep the distributors (are they 2x12's or 2x6's with wasted spark?). Add an couple of ignitor + coils (one ignitor+coil per distributor) and use megasquirt (or similar) to run them.