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MICROSQUIRT CONVERSION


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Hi Everyone,

 

I'm new to this forum but have been a TR owner for many years. I'm in the process of converting my TR6 to run Microsquirt EFI. I've got the electrics installed and intend running with the throttle bodies machined to take Bosch injectors and the normal plenum with a Ford throttle body and position sensor grafted on the end; fuel pressure to be controlled with an adjustable regulator.

 

My question concerns the return from the regulator to the tank. The standard return plumbing from the metering unit is 1/8" BSP (I think) so rather small. Being small will it lead to back pressure in the microsquirt system and cause poor pressure regulation? It would be convenient to use the 1/8" piping but does the 1/8" pipework need to be replaced by perhaps 3/8" to overcome any problems?

 

I know that some members on the forum have fitted Megasquirt to their TRs and therefore have experience of these conversions and can advise on any likely difficulties, so I'd be grateful for any recommendations/advice, please.

 

Regards,

 

Nick.

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Nick,

The PI tanks have two return pipes on the top of the tank* - one takes leakage form the MU, the other takes the rejected fuel from the PRV. I suspect if you use say 8mm bore pipe back form your sytem, and then fit a reducing Y to use both tank pipes there may be enough capacity.

Worth feeling around the top of the tank- thay are both on the nearside of the filler.

 

Peter

 

* well, mine does!

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Hmm, this probably isn't much help but I have another vehicle which is Megasquirted and that uses a 7/16" return to the tank after the PRV.

 

Can I pose another question on this... any views on the correct position for the return to the tank - towards the bottom, middle or top ? ? ?

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the 5/16 th / 8 mm pipes will suffice for returns..

BUTT, ye need to put the returns thru a filter, then into tank.

and try and get the pipe that goes into tank, as farrrrrr away frae the outlet as possible.

been there, found all the pit falls, unforeseen probs, and now weel sorted

 

Note, Bigg pipes will lessen frothy return petrol,as it has time to reconstitute itself

but a filter is still a good idea

I actually ran 15 mm copper pipes as returns when using the B26 pumps

but not needed on the small vol / pressure that modern EFI uses

but still have the filters in place.

 

m

Edited by GT6M
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Nick,

 

8mm is more thane adequate for a return. We (Ihave EFI too), are using a much lower fuel pressure than the mechanical Lucas system. I have a swirl pot fitted in my boot (trunk), and my return goes into this. I never have the fuel starvation problem when cornering and I don't have a filter on the return as it has been pushed through a filter already and a second one is overkill.

 

Cheers

 

Tony

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Thanks to you all for the replies. From what has been said it looks as though the standard return from the MU will suffice. The addition of a swirl pot is a good idea to remove any foaming from the return fuel. Does anyone have any fuel and ignition settings to use with the Microsquirt. It would certainly make for the eventual start up.

 

Regards,

 

Nick.

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Hi

 

I have just got back from having my TR set up on a rolling road, which I think is a must when undertaking this type of conversion. Saves the chance of getting it to lean and damaging all your hard work on the engine. The drive back was amazing and money well spent.

Like you I have done a two stage drill to accept bosch injectors, enabling the use of the injector plates to hold them in place.

I made a stainless fuel rail, and made use of an external fuel pump and filter from an old cavalier SRI, mounted on the outside of the car. I have kept the original fuel filter to act as a small reservoir to keep a constant feed.

We had a smooth constant build up of power and a wide rev range of torque delivery.

I'm using a canems ECU and wasted spark ignition set up.

 

Looking forward to some European trips

 

Happy motoring

 

Russ

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  • 2 weeks later...
  • 3 months later...

Question to Microsquirt users:

 

Do you use alpha-n for metering as it has no atmospheric pressure box

or did you add it and use speed density?

 

Question to all EFI users:

 

Did anyone get the single throttle body solution work properly

together with a wilder cam beyond 280 degrees?

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Question to Microsquirt users:

 

Do you use alpha-n for metering as it has no atmospheric pressure box

or did you add it and use speed density?

 

Question to all EFI users:

 

Did anyone get the single throttle body solution work properly

together with a wilder cam beyond 280 degrees?

 

Hi Andreas,

 

Initially, I used a single throttle body and it worked quite well. I then changed to individual butterflies (using the original throttle bodies), and noticed a vast improvement in acceleration and drive-ability. I have separate air filters on each pair of bodies and an air feed to the filter area. I have now made this permanent as it gives the oomph I wanted...and it seems easier to tune for some reason. I also use 'Speed density' and my setup maps are available to anyone.

 

Cheers

 

Tony

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Interesting to read Tony. I was convinced to use six butterflies

but could not compare both versions.

What I can add is the swap from stock cam > 280 > 290 degrees

what was together with the manifold design each step a good choice.

Cheers

Andreas

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One of the biggest challenges in using a cam with a large overlap is that not a lot of vacuum is produced. This affects the MAP sensor (not to mention the brake servo), which tends to fluctuate which in turn affects the settings. I got over this by fitting an alternator from a 4 wheel drive car which has a vacuum pump fitted. This was connected to my brake servo and I now have good, constant brakes. I also made up a breathing system for the engine which maintains a negative pressure in the engine and has virtually eliminated oil leaks. The only slight leak I have on the car now is from the gear selector rod o rings...not a good design unfortunately but I'm working on that.

 

cheers

 

Tony

 

alternator1.jpg

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