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MG Midget and Sprite Technical - Fuel injection for the A Series!

Have you guys seen this? Most know about Specialist Components BMW DOHC conversion, but I didn't realize they're making a bolt-on fuel injection system with full computerized management:

I live at 5,000 ft. and regularly drive the '67 Rivergate 5-speed midget up to 7,500 to service one client, then down to nearly sea level to service another. This is a godsend. When this (original) engine dies, she's getting an aluminum head and fuel injection!

JM Young

If it is just about the efi that can be done on 5 port....
Onno Könemann

It is a throttle body system for the std head. It looks like a quality kit with a quality price. I'm going to "roll my own". But I link to tinker.
Trevor Jessie

Sorry I just read Specialist Components an thought

I hope to have my EFI running for a lot less than that.
Got some motorbike throtle body's and have to get my crank pully machined and make a manifold.
Though i might splash out on 2 wideband lambda sensors to be able to map and measure on the go and save endless roling road sesions.

Be aware that the crank trigger of that kit sticks out in front of the pully and clearance is tight there to the crosmember.
Especialy if you don't want changing the fanbelt to be an engine out job!!
Onno Könemann

Onno and Trevor:

Yes - I like to tinker, too, and had considered hunting around for bits and pieces that would work. But, as she's my daily driver, I can't afford more than a long weekend of downtime at a stretch. Also, I'm not particularly computer savvy and would be daunted by trying to figure out the engine management system, mapping, etc. These Brits have done all that, and I agree with Trevor that it looks well-executed. Nice to bolt something on Saturday, and take a test drive for waffles Sunday morning.

That said, I agree with Onno that it's a bit pricey, and that the crank trigger would reduce the already minimal frame rail clearance to near-zero. This is one of the few engineering aspects of the Spridget that I dislike, and S.C. really should've figured something out that didn't make that situation worse.

Onno: sounds like you're going to modify the existing crank pulley to accept a trigger--is that right? I'd really like to see a picture of whatever you come up with. Eventually, I'll have to yank the motor to get someone to tig weld a crack that has showed up in the timing cover where the breather can attaches. So, if I can modify the crank pulley while the drivetrain is out (again), that'd be great!

I've emailed Specialist Components re: clearance issues on the Midget (the manifold swoops up a bit, and the fuel rail may be close to the bonnet), and other sundries. I'll post their responses.

One thing I forgot to ask them is why, in their video of the dyno runs, they did not utilize the pipe that goes laterally through the manifold. Am I right that this for engine coolant to heat the mixture for quicker winter warm up? If so, it'd help in NM, where it was -4 F. a couple of weeks ago, and she wouldn't run smoothly until ~ 10 miles of driving. However, under-bonnet temp is a serious concern here during the summer (100+ deg. F.). Perhaps in the summer months, when the heater tap is turned off, it might not exacerbate the problem too much... what do you guys think?

If either of you does figure out a tidy DYI EFI solution, I'd appreciate hearing about it. The original motor (60K miles), Datsun 5-speed, and 3.9:1 diff allow her to keep up with 75-80 mph freeway traffic adequately. So, a fully managed EFI system would pretty much be the final component to adapt the A-Series for my highly variable altitude/ambient temp environment.

JM Young

How much tuning work is involved with the SC kit? I didn't see anything about a manual being included or tuning instructions.
JM Morris

The kit is build for mini's and their damper has more space.

I gues they did not conect the heating pipe because it costs power to have a warmer manifold.
And you always want good pr/braging numbers.

You still need to setup the efi program to match your engine setup so there is no saving there compared to other ecu's

I am planing to use the canems ecu ( just google canems)
It supports siameese port injection and has lot's of nice features.
And is less diy than the megajolt/squirt stuf.

Pully is simple just have a normal 36-1 teethpattern milled in to the outer rim
Onno Könemann

JM Morris - They do include mapping software for their ecu, but I didn't ask about a manual. I'll do that.

Onno- Sounds like you're way ahead of the curve (pun intended). Thanks for the info. I'll be keenly interested to hear your results.

Here is what SC said in response to my questions:

Hello Joel, many thanks for your enquiry - it seems there are lots of people in the US/Canada struggling wit Midgets like yourself - your questions have been very common over the past couple of weeks!

I'll run down them for you:

- fast idle mechanism - historically, aftermarket throttle bodies do not have any means of increasing airflow for cold start conditions. (stock injection systems have idle air bypass valves for this function)

- hence we introduced the fast idle mech which literally opens the throttle plate slightly to allow more air into the engine when first starting the engine - the ecu does the rest! The other option is to start the engine and blip the throttle until a little
heat is into the engine - as classic cars have choke levers it made sense to use to utilise it.

- our ecu has built in baro sensor so it will adjust fueling to compensate for elevation changes. The ecu also registers air temp - and adjusts accordingly for air temp, it also monitors the water temp of the engine and will adjust fueling/timing to suit as well. So the ecu basically looks at what the engine is doing and whereabouts the engine is doing it and adjusts the fueling/timing parameters to ensure optimum running - as you say something of a revelation for carb cars!

- I would suggest the 50mm throttle body for a near stock 1275cc engine.

- our air filter bolts to the ram pipe

- I believe a HIF44 su on alloy inlet manifold fits into a midget without problem? - our system easily fits within the outline of the HIF carb/air filter package - indeed the fuel rail is 15mm shorter
than the top of an HIF carb

- fuel economy - running 3D mapped ignition and fuel injection will drastically improve part throttle running/efficiency - fuel consumption will improve as will driveabilty.

- the bung in the inlet manifold is for servo equipped cars.

- no need for a heat shield in this application

- its down to customer preference on whether you run a returnless system or run a second line back down the car, in either case a pressure of 3.5 bar is required.



JM Young

It sound like a nice plug and play (apart from the actual mapping)system.
Though the only bonus above other ecu's is the baro sensor.
Most motorbike itb's have an idle control.

My progress has slowed down a bit due to an fresh engine build (crack in my 1380 block)
and a "small" side project.

Hope to have my engine finished this year and the ecu running next summer
Onno Könemann

You never mentioned WHY you want to do EFI... thats the most important question here.

I looked into efi off and on, And I think doing a single throttle bodie is the way to go from what Ive seen

That said your not addressing the most serious reason why EFI is not a popular choice for the 1275...

The "Cylinder Head" ... the stock head of a 1275 is considard by the best people in the biz to be a bad flowing head... to really get the most from efi your going to need to inlist the services of peter burguss in the UK, or in the USA Hap Waltrop at acme speed shop in NC... If hap wont do the work he can tell you who will be the best to flow bench and machine the head to take advantage of the expect a cost of $1000 to $3000 to do a proper head set up

Another option to look at for efi is... the factory option, somewhere around the late 80s and 90s BMC did have a factory efi system, so it would be a direct plug and play system... you would have to do some research and see what car that the 1275 EFI was used in ... mostly in the UK, and just do a daily watch on "ebay UK" or contact several classic breaker yards in the uk... there should be plenty of the Factory EFI systems lying around on shelves and in fairly new condition as most owners quickly exchanged them out in favor of the the older carbs Su's and webbers.. So the factory EFI would be a faster, cheaper, less complicated way to go and would fit your time perameters much better

If your going to do this, and this is your primary daily driver... you really want to buy a $500 beater car that you can get rid of when the efi is done... cause this is all expermental if you dont go the factory option, plus once you pull the engine there will be no doulbt you will want to do some extra repair, freashing up... so the idea that this will be a 2 day operation and drive perfectly, is a bit over optimistic... id say you will need a good month minume if you work it 2-3 hours a day to work out the grimlins... realistically 3 months...just my opinion...

as for some good back ground info and good DIY options... look at the ford edis II system for the crank trigger system and mega squrrit system for the EFI... these 2 systems are a popular choice for hot rodders and are vary basic, fully customizable, the easist to adapt to any non stock application and inexpensive.

Keep us posted... should be fun mod to devolop, I know I will be tuned in ad watching.

Prop... Dont worry all, No efi for me! Hahahaha

Okay... I was sort a wrong on the minor basics

So let me repent and re-prove myself

I did a fast google on the 1275 efi...and here is an update/addmendment to my above info. which is actually has some good news...

1275 TPi
A special "twin-port injection" version of the 1.3 L (1275 cm) engine was developed by Rover engineer, Mike Theaker. It was the last A-Series variant, produced from 1997 through 2000.
* 1997­ to 2000 Mini Cooper 1.3i (TPi), 63 hp (47 kW) at 5500 rpm and 70 ft·lbf (95 N·m) at 3000 rpm

I think "TPI" means twin port induction... meaning there are are 2 throttle bodies hooked up to each of the 2 intake ports of the head, instead of 1 throttle body feeding both intake ports


I need to reconfigure the crank sensor attachment to get clearance due to my vertical flow radiator bottom hose location

Might have to repaint the mounting too, I fancy silver.

I am intending twin throttle bodies and considering drilling to suit pairs of injectors, biased towards the ports through the intakes

Motor cycle TBs not yet in my stash, soon maybe

Bill 1

fuel pumpd to me but I did it slightly differently on my 1275 (see details in discussion in this section entitled Sprite/Midget 1275 Turbo discussion). I actually separated the injector inlets to a position directly opposite the inlet ports (see plenum design at and also see under bonnet shot in the attached image. (Whoops for some reason I couldn't get that attached... see the under bonnet shot on the blog site already posted...not as detailed but one can make it out) The plenum was very simple to manufacture but was a proven design having been successfully used on other engines. It can be a bit less smooth under about 1300 RPM (I
Bruce Roberts

Sorry JM young

I got a note from david lieb saying you did mention your reason for the EFI... because you travel thur the mountian ranges on a daily basis... Duh, thats a great reason for converting to EFI, agian sorry about that

Another option for having the head bench flowed is to touch base with david (antoington? sorry for the mis spelling) at (APT FAST)... david A. was a college of david vizard


Shut up about the efi mini's when you know nothing about them.

Onno Könemann

manufacturers spend ages getting a fuel system somewhere near, they then spend (esp on motor bikes with wilder cams as standard )even more ages fine tweaking on the road. Fuel atomization is better in an SU than the spray produced by an injector. Manufacturers tend to use efi as a cheaper way of mass producing over a range of engines than carburetion. EFi is essential for emissions as required at the time a car is sold. Older cars do not need all this.

Pulse tuning problems were almost impossible to deal with with bosch type efi with cam changes. I think the only system I thought was good was the Kugelfischer system used on pi Peugeots around 1970; this system was sequential, are any of the modern ones?

You need to have the enthusiasm of Onno to sort the efi and programmed ignition, these are not fit it and it runs somewhere near.

I feel a lot of the time people download a generic map go to a rolling road and hope for the best. I also feel many rolling roads do not have the time required to setup from scratch and understand all the different systems. i also think some rolling roads down;load a near enough (they hope) map!

we find this with the humble VeeDub boxer engine, cos one has to remove the carbs to rejet them.....we get many vws in with very poor fuelling as the rolling roads they have visited havent wanted to take off the carbs.....what effort will be put in if the injection wants mapping? It takes us a couple of hours to remove VW carbs and tune them on the rollers.

I decided I will run cars on the rollers for people like Onno if they can 'play' with the mapping themselves, I will run the rollers and give feedback.

What is needed is an intelligent efi system which is plug and play and self learning.

If I decided to run a tuned car with separate inlet ports I would run weber sidedraughts, the aux venturies accelerate the air enough to provide better atomisation than injection nozzles. I could spend all weekend on my rollers unlimited use on my rollers at no more expense than the electricity but I would still feel I would be wasting my time with efi. I have not seen an efi outperform a muliple Weber setup yet. programmed ignition is good at low rpms and very high rpms to fill in the power curve, especially with hairy cams.

How do you manage to get up and down the hills at present Joel and how often do you make the trips?

P Burgess

Peter hit the nail on the head as usual

Efi does not give more power than a weber and most of the benifits like more mpg and better power curve can be had with programable ignition.

Why do it than?
It does not cost you power!
Easly adapted to other fuels (more bio aditives)
Posibility to get the best mpg/torque.
Switchabel between econo driving (ron95) an all power(ron.....)
Onno Könemann

As ever Peter is right!

I'd like to play with EFi just because it is "playing".

One day I might request such a trip to your place Peter.

Not this year though :)

I need to visit for a better reason soon.
Bill 1

The 'best' practice way of tuning the mappable systems is the way Onno says, buy a logging Lambda sensor such as Innovate, cruise around and set to suit. Do the final foot flat or WOT power stuff on the rollers. You will have to drive over and have a play on our rollers Onno.

We are finding the power figures displayed every 50 rpm indespensable for using fuelling and ignition to remove (as best as possible) torque dips. Of interest the torque dips get greater with wilder cams.

Midget 1275 engine we built at 9.8:1 Cr, +40 Mega pistons, Fast Road head (1.401" inlet valves), 266 profile cam, 1 1/4 twin SUs gave 40+ mpg on a round trip of 300 miles including the rolling road session.I attach a picture of the before and after graphs. The torque dip at low rpms would have responded better to more advance.


P Burgess


how are you getting on with your new rolling road? the graphs look very good for before/after comparisons.

I think I feel the need to visit again!


d cusworth

You are always most welcome Danny as is Bill.

We are getting used to the new rollers and the two part glue you put in the bolt holes has worked very well for us thanks. The most awkward car seems to be the Midget, we find it hard to get good strap down to ensure both rollers are driven well. This is due to the crappy leaf spring arrangement and the 'arse' end being light. It can mean, after a dozen or so runs we get a small drop off in readings as the tyres warm up and grip. We do not 'bed' the tyres in like we used to with the Clayton. This system relies on strapping down. The front roller is knurled for grip and the rear roller plain finish. I may try running Midgets with the pau set to a few bhp and see if that helps with more consistent grip. Trouble is the load is in 1% increments of a total of 700bhp! 1% or 7 bhp is difficult to drive against!

P Burgess

i'm glad its doing what you hoped for!

speak soon!
d cusworth

>>this system was sequential, are any of the modern ones?

All post (say) 2002 systems will be fully sequential... needed to pass emissions at/near idle when air-flow is more obviously intermittent. That is, each injector is fired once for the complete engine cycle, when inlet valve open.

My Rover K is 2001 and uses semi-sequential injection, that is it fires 1&4 and 2&3 injectors together - the engine doesn't mind 2 squirts of half the fuel needed for each port, even one with the inlet valve closed; it doesn't affect power - only small impact on emissions (as mentioned above).

To go fully sequential (which I won't ever need to do...) I'd need a cam sensor so the phase of the engine is known. The Emerald has a setting for this state (and a pin or 2 on the connector for additional wires).

[I must confess when I first ran the engine, I set it to fully sequential; it defaulted to a condition where it ran OK anyway! After disucssion with Karl at Emerald, I paired the injector wires and re-configured the ECU settings. No-one was to know my error!]

BTW - the VVCs always had cam sensor and fully seq injection AFAIK.

With siamesed inlets, the A series engine presents an unusual challenge to EFI, as you know.

Anthony Cutler


I never Claimed to know anything about the factory Mini EFI system ... only that the mini efi system did exist and is an option

Yes the mini EFI system did exist from the years 1997 to 2000.. Its a fact, regardless of your apperant limited knowledge ...look it up

Change out your rag buddy, take some midol... and relax, Im not your enemy.

>>>>>>Onno Könemann, Netherlands
Shut up about the efi mini's when you know nothing about them. <<<<<<<<<<<


"Prop, and The Black Hole Midget

I think "TPI" means twin port induction... meaning there are are 2 throttle bodies hooked up to each of the 2 intake ports of the head, instead of 1 throttle body feeding both intake ports"


that is why i said:
Shut up about the efi mini's when you know nothing about them"

The efi mini's made more power when put on a carb and where only made to comply with exhaust regulation.
They had a single TB with 2 injectors.

Twin Point Injection.

So not an option.
Onno Könemann

Peter I know why you are a god.

You come in say something contraversial and everyone changes their opinions of a few years

I am not worthy!!

For the past couple or so years EFI has been seen as the holy grail by most here now all of a sudden it is simply a plaything! ?

Anyway Once a weber fan always a weber fan I say!

Nice one Peter.
Robert (Bob) Midget Turbo


where the injectors attached to the head directly ???

Im not sure I understand why the mini efi system is not an is the same 1275 engine as the older 1275 Plus... worse case cant the head just be swapped or re-worked

Still EFI would be the idle induction system for JM young for what he is wanting to do, wouldnt it?

he is not looking for a performance upgrade but rather a way to drive thur the mountians on a daily basis without having to do a carb adjustment everyday

I know those moutians he is talking about ... It is tough to drive though those wide range of elevation with carbed cars... its not uncommon to go from 4,000 ft to 14,000 ft of elevation in the course of an afternoon drive

Maybe Jm young asked an even better question.. is there a better option.


Hi Bob

For years I assumed the injection 'had to be better' per se. My old sd1 Vitesse seemed good on the injection, I could only run a very mild cam as I was told by the guy who designed the system it would take 25% more air flow from head work and still work correctly, change the cam much and you are in trouble with pulses....the same system with downdraught webers made 30 bhp more!!!! The injection was a means to an end for the factory not a means to an end for us tuners. Take the Calibra Vauxhall red top thingy...showed 142 at the wheels on my old rollers....put the engine into an old Escrot, add a pair of Weber 45s and see the power go to 168 at the wheels!

I think some are attracted to the computer approach to tuning as they can see it on the screen. Sadly the number of load sites makes it damned nigh impossible to get it right. Without alot of hard work. We ran a B with a 45 on it today. it showed about 13 afr everywhere foot flat....drilled the main jets from 145 to 165 and we were bang on 12 afr everywhere and up 5 bhp. Cruising and pick up for driving away still a little weak so we drilled the idle jets from 55s to 60s. Job done and customer now has smiling face.

I guess I am in love with Webers ....mind you they do stink of petrol dont they :) And as Prop says...they wouldn't be too great up and down those hills!

I wonder if it would be easier for Joel to alter the fuel by adding a little pressure to or depressurising the float bowls to compensate for the altitude pressure differences?

P Burgess

It would cost him power!!!
That 1275 on carbs would deliver +65bhp
It is not adjutsable in anny way.
Onno Könemann

Peter, it seems you are comparing a poorly designed fuel injection system to a well designed Weber/manifold setup. What exactly is your point?
Trevor Jessie

Hi Peter guess I will need to copy your post and paste it the next time this lot try to convince people that webers are not too good.

I think the biggest problem is as you rectified today the Primary/idle jets. These are so important for smooth running and cruising speeds. Everyime I see a weber set up that someone has complained about (Many years) the primaries are too small. Generally 50s fitted I always end up at 60 but do occasionally get away with 55s assuming the chokes are well sized. :) just need my own rolling road and I would be happy!!
Robert (Bob) Midget Turbo

Gents, maybe I may add something to this topic. I run a 1275 supercharged EFI sprite. I run the Megasquirt for only ONE reasing: full control (incl feedback from the WB sensor).

I started with a turbo SU, but for me (with no rolling road at hand) I was immediately confronted with the limitations of the SU regarding tuning
a.o. arnold

Hi Trevor

I am trying to say stick to the KISS principle and one cannot go wrong so easily. People try too hard. I am not sure what you mean about poorly designed injection? webers are pretty basic too as is the manifold design. Solex triple jet sidedraughts are more complex and produce better results.

I also forgot to say how badly efi systems react to changes in the wiring integrity with age, less bullet proof than Olde Worlde Carbies.

My Jimny gets upset with short runs and displays a warning light, reset it and it is happy fpor a few weeks. I have a Mitsubishi Pinin 4x4 with a GDI engine, mpg is brill for a 2 litre 4x4 but the sytem is easy to fool, a little hard on the throttle and the fly-by wire doesn't quite follow.

I am trying to say carbs cover a wider range of performance.

With digital fuelling the software has to tell the fuelling nozzle what to do. With a jet reacting to pressure drop and changing in proportion to the signal the system is working within nature. The digital system relies to a large extent on the programmer and it does not 'feel' the nature. I suppose in Behavioural Science terms it is Second Hand knowledge versus the carburettors First Hand Knowledge.

P Burgess

Granted, the more complex a system, the more things that can go wrong. However, a computer controlled system allows the tuner to decide how the fuel nozzle reacts to engine state. Minimum requirement in my opinion is TPS, MAP, coolant sensor, wideband o2. Then you can also add additional parameters such as intake air temp, egt, maf, etc.

I contend that a well designed and tuned EFI can yield as much HP as carbs, but have the added benefit of being more fuel efficient and better drivability.

Trevor Jessie


You posted while I was typing away. The problem I have with WB sensors is they like to be very close to the ex ports for heat with a pretty clean environment in terms of fuel. They are all to easy to damage with excess fuel. We have WB sensors on the rolling road (special NGK ones at silly cost) and Bosch run of the mill sensors on the Innovate system. Unless we get close to the ex ports we get poor readings at idle and part throttles as the gas temp is not high enough. My point is with OE efi systems the manufacturers have spent alot of time and effort trying to smooth out the bugs. IMO most efi cars have little quirks and irritations people accept which they might well find unaccetable with carbs. The efis seem to be easy to upset on trailing throttles when the fuelling cannot quite decide whether to shut off or what...kangarooing ensues!

I am not a Luddite or I wouldn't go high tech with my dyno and monitoring equipment.

Think how infinately variable the SU is in terms of fuelling and compare that with the number of sites you have with the Megasquirt. You say you could not tune the SU without a rolling road. I am not sure the squirt is much better? You could have used a WB sensor, logged the fuelling and got it closer on the road with the SU. In terms of needle position we found by the simple expedient of filing a notch in the needle we could see from the blip on the log when we were at that point on the needle.

P Burgess

Hi Trevor

I think the basic throttle body (Weber style) systems will almost match straight Webers but the atomisation with any efi is much poorer. The very technical manufacturers efi systems which are very economical as you say do not produce as much power as Webers although they will be more fuel efficient ....more like an SU?

Motorbikes hung on to carbs for a long as possible compared with cars even though the carbs are more expensive to produce I would imagine.

How much would a proper setup as you describe cost compared with say a pair of SUs and if you are talking in terms of MPG improvement how long would it take to recoup the costs?

Many many times we see cars suposedly set to perfection on a rolling road with mapping are poorly done. It takes along long time to setup from scratch and costs a lot of money. It needs, as I said at the beginning, a real enthusiast like Onno to set one up.

I rather admire the American Holley way of being somewhere near in terms by a carb suited to airflow requirements based on engines size and fit, adjust and forget as they are close enough.

P Burgess


you rasied my eye brow when you mentioned air pressure

>>>>>I wonder if it would be easier for Joel to alter the fuel by adding a little pressure to or depressurising the float bowls to compensate for the altitude pressure differences?<<<

Is it the limited air pressure affecting the carbs at high altitude, or is it that the oxygen level is much thinner at higher altitde

I was kinda thinking in the past hour that perhaps Joel could hook up an oxygen bottle and connect it to the inuction system like a NOZ system activated by somekind of altimeter type sensor.

But if its air Pressure that affects carberation at high altitude... the oxygen bottle wouldnt work ... unless it was pressurizing the carb somehow

If it is extra air pressure thats needed, could additional restriction at the venturies of the carbs be the answer... like a shop vac, where you use a reducer at the end of the hose to create more suction.


EFI is by no means cheaper than carbs in terms of initial cost or tuning. Here in the US, there are many guys that "build" streetrods. These cars need to have excellent driving characteristics (in terms of idle/ cold starts/ AC idle/ etc), but still be able to perform very well when they go to the drag strips. For years many people turned to Holleys for easy setup and excellent tuner support. However, people are now wanting their fun cars to have manners like their daily driver (until the loud pedal is mashed). Carbs can not easily make this happen.

Ultimate power as in peak HP? I believe that it is possible to set up carbs to beat out a fuel injection system. But if we add all the other criteria, FI wins in my mind.

I did see a rather elaborate FI system that used a cam sensor and sequential injection. It was a total custom fabrication (including the ITBs). The creator was explaining all the various tables and modifying tables and it became obvious that he had spent much time on the tuning. He said that he made the swap to FI because he wanted the drivability without giving up the performance of his 2-four barrel carbs.

That is an extreme example. What about the guy that wants to be able to do his own tuning? Lets suppose a person changes his headers/exhaust and air filter configuration, with carbs he may need a trip to a rolling road, but with most FI systems he can simply log a bit of his driving and go make the changes on the maps.

For someone that needs adjustment for elevation changes, FI systems can easily sense atmospheric pressure and modify the maps accordingly.

So, in my mind: carbs=ultimate power, but with drivability compromises, FI=near ultimate power, but with ease of tuning and great drivability.

The local chassis dyno has a full time operator, but freelance tuners that specialize in various FI/carb systems.
Trevor Jessie


Just reading between the lines.. I think what peter means by EFI being cheaper is from a manufacturing point of view not from a one off set up... once the factory works out all the bugs... then its just fire up the trolly press and let them fly exactly the same one after the other 24/7 for months at a time

as for one offs both side of that equesion gets expensive fast.

Peter - My stock '67 1275 high compression will climb the long hill from Albuquerque (5,000 ft) to Santa Fe (7,500), but gets noticeably less responsive. She's a daily driver here in town, and I make the SF run and/or head south (losing anywhere from 2,000 to 4,000 ft) a few times each month. It'd be really nice to zip up to the top of 10,000 ft. Sandia Crest for a picnic, immediately east of Alb, without losing so much of the car's wonderful responsiveness.

After trying Moss's leaner needles, which made her run terribly, I'm running standard needles with K&N filters sold by Moss, which after readjustment have leaned up the mixture enough to make her run tolerably well.

Frankly, I love the SUs, as carbs go. Easy to clean, easy to adjust, elegantly simple design. That said, what the SC setup evidently does automatically--adjust for barometric pressure, engine and ambient temp--seems like a neat idea, purely from the standpoint of drivability.

Onno - what a lovely 'side project.' I look forward to following your progress, and hearing how your EFI car runs.

Thanks to everyone for taking the time to post; I've learned quite a bit from listening to your discussion.

JM Young

Hi Joel

Some of the problem is (as Prop says)lack of O2 at altitude you will not overcome the power loss unless you add a supersharger for altitude :) My thoughts were in terms of using pressure loss/gain compared to Your 'standard' conditions to alter float bowl fuel height or pressure on fuel (same thing?)


I do mean cheaper from the point of view re manufacturing costs, one size fits all methinks.


I still feel the time spent on efi might not be as good as you say. You can still log and change the needles, jets and accelerator pumps of a carb. It is simpler to install Lambda /sensor/sensors and alter the fuelling by jet change than install an efi system on an old car from scratch. You just need data logging facilities which is what you also need for efi. Efi still does not respond the same as carbs. It has to be told what to do and it does not fuel by instant pressure drops to the source of the fuel. Even VWs on a single carb in the middle with long intake runners seem more responsive to me. Do you feel modern factory efi cars drive as well as a factory set carb system? All the efi cars I have driven have annoying quirks I dont remember with carbs....apart from cold start! With regard to mpg most modern cars do more mpg cos they are ligfhter and more aerodynamic. The 4 valve technology for emissions is not as torquey as our old 2 valve technology.


P Burgess

Hi Trevor

I would just like to add....I am not trying to say 'DO NOT FIT EFI' . It is a project which will challenge and reward and punish just like any other and so worth doing for the experience and good of the soul etc etc and as you like to tinker, what better reason could there be?

I am trying to say,imho, the use of our classic cars does not warrant hi-tech efi, we dont need to meet such stringent emissions. Our cars are basic and from there derives some of the pleasure of ownership.

I know it is off subject, I love riding my Harley Skirtster down the road. Basic, black with shiny exhausts and handlebars, no fairings or suspension (!), rough running, enough vibrations to shake fittings an old Brit bike but without the oil leaks :)

It would be easier to uprate carbs for modified engines, many many tuning firms out there have stunning experience and knowledge, we have a Weber specialist at Chesterfield who can give you a carb to fit set so near it is eerie. There are too many efi bitsa kits out there to pool knowledge of a near to run map.

All things said, I hope you enjoy the challenge and rewards of efi'ing your motor.


P Burgess

OK... final note from me.

I have one last reason why our cars (or at least mine) would benefit from EFI: it would keep my wife from fouling the plugs as she forgot to turn off the choke... again.

Trevor Jessie

The kit looks a good one; and by using single-point injection, they've avoided the problem of 2 siamesed inlet ports and no cam phase sensor. (I see they still use 2 injectors, to avoid mod to ECU!)

[Problem with A Series is: firing order 2-1-3-4; but this gives suck-suck-nothing-nothing on front port; and reverse on rear port; you don't know cam phase, so must fire ingition and injectors for 2&3 together and 1&4 together... but that means both ports together... which means both injectors needs to fire 4 times per cycle even though on 2 consecutive occasions of the 4 there's no inlet open, and hence 3x more fuel available for first of each pair than the second. Nightmare. Hence easier for single point injection.]

Being able to map for air and coolant temp is great; not just for the main map, but for the acceleration enrichment and starting too.

And it has compensation for barometric pressure - without this, for you the kit could be worse than carbs (which at least compensate to a degree for altitude changes).

Plus you'll have 3D map for ingition too - much better than the 3-straight-line mechanical approximation to the advance curve and vac advance for part-throttle operation.

As you know, I love EFI... being able to put numbers in boxes/cells to the events in the engine makes sense to me.

The proof of course, would be to compare the engine on a RR before and after.

As Peter says, setting up 3D maps for ignition and fuel is time-consuming; most RR will set for WOT only - you should also try to pin down cell setup for your main cruising throttle & revs; find out what they are from the ECU.

I have spent a considerable time 'perfecting' the maps on my Kseries, based on WOT setting and then extrapolating each for part-throttle across rev range. You need to have a good idea about the shape of each of these maps before you start... else you're heading for no improvement or even worse.

I had a Weber-45 on BRB for around a year; these days I make do with sucking down the nasal cavity to make the 'Weber noise' whilst the EFi is doing its stuff. Having said that, carb-wise I'm firmly with the SU brigade. Each to their own!

Anthony Cutler

sorry guys, this leads to nothing. There are good reasons to keep the carb, and there are good reasons to ditch them. For myself it was crystal clear, I wanted:

- full loop back
- full control over ign and fuel
- no mechanical issue as wearing of needles or whatever.

I am not sure if I loose any power, in fact I do not care at all. I raise the boost a bit if I want more power. What I do want is to keep the engine. I my case (in fact all FI engines) pinging is the MAIN danger. So one needs full control over fuel and ign... (IMHO)
a.o. arnold


One still needs a rolling road and skills to do the tuning whether it is efi or carb.
I had a mini on the rollers this week, the guy had a megajolt with a 1293 map to run his turbo A+ engine. He does not know how to work the megasquirt. Luckily he was only in for initial tune so he can get some miles on the engine. Bad news he is boosting straight to 20psi...good job he came down to say hi....he will sort the teething problems out then come and see us when he has mastered the megajolt. I was happy with his fuelling on his standard su.

The problem I am trying to get over is that setting up the efi and ignition requires skill and perseverance as does carb/dizzy tuning. It is not plug and play like a computer game. It requires 'specialist' tuners like yourself and Onno to make it happen. I don't see how you bypass a rolling road even if it is just to confirm you got it right? Sometimes the problems don't show up until the engine is worked hard such as run what you brungs, ciruit racing, hill climbs/sprints or even have-a-go days. We are not just talking about road use, with one owner with one engine. I am talking about the whole spectrum of engine use. It varies across the board and we get to see lots of different engines/people/philosophies and I am just trying to pass on what I observe. It may help someone save some money by not wrecking their engine.

P Burgess

Oops...I meant he does not know how to control the megajolt :)

P Burgess

I agree, tuning for optimum performance needs to be done on a rolling road. However, the last FI retrofit I worked on was a 455ci V8. I did most of the tuning while sitting in the passenger seat as we put the car through various runs. Then once we felt it was very close I smoothed out the maps and we did some more runs and logged the results. After examining the logs I discovered a couple areas of concerns and made some more corrections. Total time required just for the initial tuning was about eight hours. After a couple weeks of casual driving to sort out any other mechanical glitches the car went to the rolling road for final tuning. We had everything pretty much dead on, but he made several timing adjustments and gained a few more HP in the WOT portion of the map by making some fueling adjustments. That was an area that was hard to tune on the street.

Having typed all that... the FI system was purchased as a kit and it had a "base map" that was supposed to be "very close" for the engine setup. It allowed the car to run and drive, but it was WAY off. At times the computer was making 35% corrections to the fueling map based on the wideband O2 readings.
Trevor Jessie

Hi Trevor

My friend who used the Innovate and little steps in the SU needles did the same effort to tune as you have. He spent many many weeks at the task. Some years ago one of our customers had a Fiat with a pair of Webers, he used one of thos K&N AFR monitors and got pretty close. He was just a little weak at higher rpms where he couldn't find the right angle and length hilly roads to do the top end. We also tend to find the rolling road under load conditions is a good way of checking for detonation, which shows up as bhp drop or noise or both!

The above examples, yours too I believe, are tuners who know more than the average driver and work hard to get somewhere near. All these people, I suspect, have spent many years learning their art. I do not think having efi/ignition systems which are computer run cut much off the 'real' learning curve. I also suspect those using Megasquirt/Jolt are trying to do it all as cheaply as possible and that once fitted will never have a problem many of us are still on 15 year old computers I wonder?

P Burgess

Talking of which, I believe that there are some ex F1 cars out there which are unstartable becuase they use now defunct software on extinct computers.
Gary & Gaps

NASA did a search through pc junk jards/second hand shops a couple of years ago.
The space shuttle and controle systems run on pc's/software that is totaly ancient and had no more spares support!
Onno Könemann

This thread was discussed between 13/02/2011 and 19/02/2011

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