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MG Midget and Sprite Technical - A series max power

Just out of intrest whats the max useable power/torque that can be obtained from a road going A series engine.
Engine must be able to do 30k between rebuilds and driveable on public roads.
Tim Dalton

with a turbo
180 should be posible

you would be in the steel cranck/h-beam conrod level of tuning

but 30k between rebuilds is not that much and 200+ bhp has been reached on mini's with turbo's
Onno Könemann

For normally aspirated engines, the numbers I've heard most often are:

60 ~ 80 hp for a 1275

80 ~ 120 for a 1380

more, and less, can be achieved depending on the care with which the engine is assembled and how well all of the components are balanced with each other.

Norm Kerr

120 from a daily driven 1380 thats tactable in traffic, etc

Someones been rolling a race engine or their rollers are a tad optomistic

Would give my lefticle to see a reliable, daily driven 1380 with a genuine 120hp at the flywheel.... N/A

not restricted to 5 ports
Tim Dalton

It depends how tractable is tractable. What one person loves, someone else will hate, either because it is too lumpy or too timid.

One of ours is a 1275 with a 286 camshaft inherited from PO. Some think this is too lumpy, I would have too till I actually drove this one. (And it is definitely a 286, I've checked it.) Sure it's a bit waffly at idle but driving it is fine. For me. Others may not think so. Which illustrates the problem of defining road going and driveable.
Paul Walbran

Nothing wrong with a 286 in a road going 1275, with normally aspirated engines it has been my cam choice for years. Just make sure you have plenty of compression and a well balanced engine and things will be good.
With that combination somewhere between 110 and 120 at the flywheel is not out of the way.
That I would suspect is about the limit for a reliable easily drivable Normally aspirated car.

Now with a turbo or well geared Supercharger I can only guess but my turbo must be in the region of 150 at the flywheel if not substantially more.

If I get the modified clutch finished before the MGCC midget Register rolling road shoot out in November I will know for sure :)
see here
Robert (Bob) Midget Turbo

if you go the 7 port route then 120 bhp from a 1380 should be no problemo.

if you go to a EFI set up you can even run wilder cams while still keeping it drivable low down
Onno Könemann

7-ports/8-ports, EFi, etc etc

What about an actual a-series.

The cost of doing the 7/8 port heads would far outweigh your want for a quick daily driver engine.

The EFi and forced induction route is again a costly one if done properly - ie dont just bolt on stuff and expect reliable hp.

Fuel Injection is a great idea, but there is a huge difference between throwing something together and having a system which can be mapped accurately and give you the results you are looking for - not to mention the cost of a "proper" tuner to do the map. I would dare say that all the costs involved in doing an EFI setup would be recouped from the engines fuel economy over the 30k miles

it depends who is doing the driving on public roads. My 1380 has 90hp at the wheels, but my wife won't drive it now! Mine has done over 30k. I broke a piston on the track, but only replaced the pistons and rings. I would not have needed to if I hadn't missed that damn gear!

I only want 1HP more than Shauns K series :-) preferably more, but i would be happy with the 1HP.

Brad 1380

Brad - :D

That's a tad horny looking.

Tim, buy yourself a copy of Vizards or Danial Stapletons book. They discuss every mod with the possible gain and with some info on drivability versus nippyness (is that plain English?)

Keeps you off the street for many days and helpes you with your X-mass wishlist.
Bas Timmermans

i've still got the SC inlet to make, a HIFF44 BOV adapter, some plumbing for the intercooler re-circ valve, mega jolt wiring & to weld in the wideband, busy times.

Brad 1380

Very nice dude.

Megajolt seems to be a very good job, and of course being opensource has almost endless amounts of help available online.

My main concern with it it user error. I've mapped a few honda's in the past using Hondata and Crome, but most of the time problems occured when the owners then went and changed silly things like the VTEC changeover point and as such ruined their engines through abuse.

Will certainly be interesting to see how yours goes. I am imagining its far from stock underneath all that green paint?

Are you having any difficulty with clearing the bonnet? I dont imagine you are considering the dashpot sits the highest, but after all the pipework, etc are you running into any difficulties?

Peter, the HIFF adapter for the blow off valve will lower the carb enough to clear the bonnet...i hope.

I'm keeping the exact spec close to my chest at the moment in case shaun decides to go all out on his K series build, then again i might be into a 50K miles rebuild by the time that gets out of his garage.

The main problem is siting the intercooler, but i think i have that sorted now.
Brad 1380

fibreglass front valance and cut a big hole ;)

if you want to keep it close to your chest, but fancy sharing - email me dude, I can be very discrete :P

'I can be very discrete :P '
Home visits a speciality?
Brad 1380

;) Camera and notebook in hand :P

who ever mentioned the cost?!
i thought it was just a mind exercise ;)

but when it comes to reliable bhp for buck 90ish from a 1380 is a driveable realistic i think.
I hope to be around that mark (need time/money for the rolers)
Next goal is to get an EFI setup together&running
Onno Könemann

my 2 cents ....

Id use the 16 valve BMW K-series motorcycle engine clyinderhead conversion,(see link below) a ford edis ignition system with NOS injection, cryogenic frozen fuel feed into holley double pumper on a tunnel rammed wet SC blower...running on that will have some pop....for 12 secounds anyway


OH Man, WOW, and OMG all wrapped up in one...

I was just kidding being that price was no option...But having a look on ebay the BMW K 100 duel cam cylinder head in 8 valves is really cheap under $200 on ebay with several to choose from...and the link above im my pervious thread has a complete kit without head for around $750 So its a complete bolt on and go kind of thing all the engineering sorted

Im seriously going to have re-think about this...For a $1000 bucks and have something truely rare and seriously cool, and ultrafast...thats more temptation then I can say NO to, this is going to be on my mind for the next 2 weeks .... Oh Im so screwed, thats So doable

Perhaps I need to but the brakes on the engine build as Ill need a differant (lower) CR If I added a blower to the BMW K 100 duel CAM cyinder head

Now what the heck do I do.... Im thinking this could happen



You have got to be kidding me! ... 230 BHP with forced induction...see mid way on the link below

yeah know if you knief blade the butterflys in the carbs, Id imagine you could see a grand total of 250 BHP...LOL HAHAHAHA!



Have a look at this

The company is only half a mile away from our house!


Andrew McGee

Our 1380 has 112 bhp at the flywheel, and apart from a dropped exhaust valve head during a track day at 7000 rpm, has been very reliable for the last 35,000 miles.

Piper 276 cam, 1 5/32" / 1.4" valves in 12G940 flowed head, 11:1 CR, HIF 6 on flowed Titan manifold, Aldon Ignitor ignition (planning for Megajolt), Maniflow large bore LCB into 2" o/d exhaust system, etc. etc.

Very tractable and responsive, so an easy 20 mph in 5th or 7,000 in 1st, 2nd or 3rd! Have'nt hung on to 4th much beyond 6,000 (106 mph) as it will pull very well in 5th (Toyota T50 box).
Richard Wale

Thanks andrew

I just found a 16 valve BMW head....nice, its set up for the mini cooper and has fuel injection, And a vary good price tag esp considering a 7 port head with fuel injection...Im certialy a fan, This my sound retarded But I think I like the 8 valve better then the 16, just less moving parts and simpler set up...for me its a less is more kind of thing when you compare the 2 (8 vs 16 valves)

on the 8 valve head ... is one side exhaust and the other side intake....I cant graps how the cam opens the valves ... (timing)

Im guessing just the belt on the front crankshaft pulley ...would that be correct, If so, that would make a Ford edis ignition systm really easy, wouldnt it?


Go for it Prop you are just the type of guy that kind of project needs.

I hope you will fit it to a turbo while you are at it and we will have a member of this BBS with a 200BHP A Series engine!! Well part of it A Series!

Even if you can't get it running you can sing about it everyday! LOL
Bob Turbo Midget England

Been a frightfully interesting read this thread - since Pete is convinced I'll have a 1275 before Prop's car is on the road - and, with that new post...!

Bob - why don't you bring that turbo midget to the next Autotest and prove to me that it's worth it!!!!

Well after some additional thinking....IM GOING FOR IT!!

Just not yet, Heres the plan after I get the car finished, Ill get a frog/bug eye sprite and do the 1380 with the BMW K100 clyinder head on it with some kind of small blower

like this one on ebay ... 360292716934, a little over driving the pulley I should get around 10psi of boost ... (maybe)

then build the bug eye with fiberglass (or make new panals out of carbon fiber...lots of info on youtube)big brake kit, rx 7 rearend, frontine suspension, tilton masters, Datsun dog leg 5 speed, lambdo door kit, nice roll cage, alloy alum mag slots, quick release steering wheel...ect

Ill tell ya, with everything Ive learned on this current build this next engine will be a cake walk, Im definatly getting pumped up with excitement about this next engine build...I hardly slept at all last night... the mind is just racing at top notch,

I saw some carrielo rods at dirt cheap price recently, I just cant remember where and I know where I can get hold of maybe 2 EN40B chrankshafts, that will need to be wedged,indexed and nitrated, definatly need All 3 of those 4 bolt main caps for the A+ and have modded to the reg A series....this is going to be so freaken cool.

Prop, stop wasting our time by having to read your dumb posts.

Tim, I think Richard has it on the head for a N/A engine, forced induction I guess the skys the limit. Bob has built an engine with quite high power outputs that sounds and looks very tractable on the road.

Hey Tarquin,

Im not sure I understand what you mean about a dumb post...Do you mean building a 1380 with a BMW K100 clyinder head and a blower IS a bad idea???

If so, What draw backs or negitives are you aware of that would make it a dumb engine... It certianly seems impressive to me


The drawbacks, Prop, are that it takes time and sorting out to do, and you've not been able to get your only very slightly modified engine to run yet.

He was being sarcastic that you spend too much time talking here about grand plans, on the forum, and too little time working.

Norm Kerr

Norm, bingo.

Goodness, I thought Prop was joking.
Trevor Jessie

heres another sleepless night for you prop

Ah ... I gotcha! I thought the new engine idea had a huge flaw in the design or something that wasnt vary appearent

Sorry for taking the air out of the room, I fell victem to the inspiration of a new canvace to work on, and when I stumbled on the possiabilitys of what can be done...I knew it right then and there...sorta of a "meeting jesus on the road to damascus kind of thing, ya know"

Yeah this Current build did get a bit taxing didnt it? Im so glad Im still on track to have it runninng in 6 days from now! As long as the UPS truck dosnt crash into the lake or one of the machine shops catch fire...really the ONLY real issue I can for see Is the needles being to lean, but thats a no brainer at this point

I got some good research in today for the new engine build, the good news, I cant see that build beginning till well after midget 50 next june. I got way to much work on the midget between now and june.

But Im stoked about the new engine build....I even cleaned out the closet (Agian today) so the parts collection can begin as stuff goes on sale.

BTW.... Thank you for backing me up BOB Turbo. That was cool of you. and Im vary appericative for the comment of support

Also considering the K100 8v head for the spare engine.

With wanting to have Kerry out competing aswell (despite having to get my own car competitive) I feel the need to delve into the machine shop with an otherwise worthless 1275 block and begin the modifications required.

I would go for 16v, but i fear the power band would be too high to make for a torquey autotest car. We shall see.


hey peter.

Thats exactly what i found out... the cams dont come on till around 3000 and maxes out at 7000

an interesting point the K 1200 has longer valves then the K1100 and the K100 so Im guessing the with a good cam grind on the K1200 the cams may come on a bit faster

But Im with you... I think the 8 valve may give better options then the 16 valve....Just less to do more with... besides the price tag for a 16 valve is steep if you can find one from what Ive read

besides Im thinking it will be alot easier and safer to pocket the piston crowns for 2 valves instead of 4 valves

Tomarrow Im going to drop in to a local motor cycle shop up the road and find out who the players/movers are for BMW motor cycles and what I can find for performance upgrades for this head.

Prop, you can't leave home tomorrow, you have stay at the fence waiting for the courier!!!
Alex G Matla

Im ahead of you alex...

I got the lawn chair and the cooler already on the front porch...Vigil begins at 9:30 am.

its like christmas eve... just counting down the hours


I would go for 16v, but i fear the power band would be too high to make for a torquey autotest car. We shall see. <<<< GO FOR IT PETER!!!!!!! I think it would be the best option available at this stage :)!

Prop, I fear that it is because the rest of us can't cope with the idea of you doing another ruddy engine, and, I'm with Trevor - I was hoping that you were joking. Get off that ruddy lawn chair, into the garage - send the UPS man there - and get working, coz, 6 days ago, you reckoned you'd have it on the road LAST FRIDAY.

Rach - in time, when the money allows.

Prop - what you on about pocketting pistons etc etc. Just throw it on and see how you go. Dont over complicate it like your current build.

However, i really really fancy a single Jenvey 1"3/4 throttle body and run megajolt on both the fuelling and ignition side of things.

All pipe dreams that I will get round to some day, but my wee book of ideas is exactly that, a book, at least you can access the forum for your ideas Prop :P

Peter ...

Im disappointed... you have "A" book! you should see My book shelves of various ideas, I once had a girlfriend that called it the 2nd hall of Alexandia...LOL

pocketing the pistons ... yeah I read that on a mini forum, But they where refering to flat top pistons, It has to do with the angle of the 4 valves sit at, Im guessing with dished pistons probably not an issue, No mention if the 8 valve head needed the pistons pocketed...But Id think it all depends on the set up you'd have, type of cams, aftermarket valves, valve timing all the usally suspects, that are cousins to the gremlins ... but pocketing pistons isnt an issue to lose any sleep over.


I hope things are well for you, you seem a bit bitter lately. I feel ya, Lots of pressure here to, Im seem a bit more on edge myself. Hang in there kid.


haha, Prop, this isnt "A" book, this will end up being "THE" book.

With the serious development that goes into a lot of the irish cars, now and then you will see something and have to jot it down.

It lists part numbers of all the gucci parts we could need from the likes of Goodridge, Earls, Aeroquip, Koni, Ohlins, AVO, and many many other really nice bits. Also has 4/5 link designs, all midget dimensions i'll ever require, wiring schematics (not those dodgy haynes diagrams), drawings and dimensions for different backplates, sump guards, other custom parts, etc etc. Basically anything i couldnt find in books or online.

Peter All kidding aside....

Your on the right track, I think keeping a book,or a diary of mechanical ideas is Just the way to go, esp if your the machanical creative type, which you clearly are, Most people wont understand that concept, but you certianly do...I have to admit, I dont keep well enough notes like parts and vendor numbers...But I think it shows disapline that you can, I hope you keep up the practice, I really belive it will serve you well in the long run...If for no other reason I wont be the only one that looks like a wacked out kook when I die. Cause someone will have to look thur all my books, shelves, binders, napkin scribbles, odd bits of paper and scratch notes. and when that happens it wont take long before there gonna scream out with mad terror ....WTF!!! HAHAHA

Hopefully Ill have enough advance warning to burn it all before I go. hahaha

All told, I find a blank book and pen in my by bed is my only link to sanity. At times I cant seem to write and draw fast enough or long enough to shut it all down



I hope Your "THE" book will be just the 1st of many great additions....And I have a sence It will, ultimatly It can define you If you allow it to.


LOL Prop - when I get exasperated with you - it's not ALL to do with me - honestly!!!!

Things are good - apart from the obvious nightmares about my dad's arrival today - and the one in which I have Primeroses' engine in pieces in front of the Rayburn is particularly disturbing - since we're off to Holland in 48 hours ;)

I'm suggesting it's a great idea to Pete coz, well, I might not roll over and play dead when they say they are coming over like some of the Lincs lot - but, every advantage is good ......... :P

You'd so better have that car running by the time I get back from holiday :)

will Do rach,

Im Curious, what does your fathers arrivel mean to you?

you've mentioned him several times in the vain of apperhinsion, But as a general norm, you have lot of love and respect for him as well.

>>>>>>>>and the one in which I have Primeroses' engine in pieces in front of the Rayburn is particularly disturbing <<<<<<<

Thats nightmare that can screw you up for life, I dont know who rayburn is, But Id call him before you leave just the same to say..."HELLO! I like our friendship" lol least he will be thinking of you if primrose does decide to take a defiant attiude, Your car WILl make it to holland okay wont it? any issues you want to share with the BBS, Im sure all our friends on your side of the pond would find it a gentlemans honor to set up a series of check points for you to ensure your mechanical viability on your journey...Trust me, I know they are there for you just for the asking.

Heck Im a great example of that... they still havent stopped helping when I ask, so thats SAYing something.


LOL Prop - sorry to confuse you ... and, for the record, the engine is very firmly IN the car - and working ;)!

The Rayburn is a sort of cooker/boiler/lambheater/stove/centre of the kitchen and very warm (hence, at least, even in my nightmares I'm thinking of my own personal comfort!)

Yeah, my parents are pretty good really - hence why he's coming down to do the animals for me so I can go to Holland at all - but, my mum is clean to almost the point of obsessive and organised within a millimetre of her life - so, I always feel somewhat inferior to her abilities! I think also they wish I'd gone down the line of polishing the car, like dad, rather than taking it to pieces like my uncles!!!!

She'll make the journey - baring any emergencies which are totally unforseen - and, since I risked the teasing of Arie to ask what I needed to take, then, I've discovered another few inches that more tools can be fitted in ... ;) I'm looking forward though to catching up with Alex and Onno as well as the weekend - and hope to FINALLY!!!!! see Onno's "cousin of Primerose"!

I think, Prop, that Fraud would have nightmares trying to bring some reason to my dreams, so, if I was you - I'd laugh at the dumbness of it all - and put it down to another mad Brit trying to save another couple of fractions of seconds ... ;)

How does an 'A;' series distributor work on these OHC heads? Is the old cam left in place or something?


p.s. Prop. Go for it and ignore these miserable buggers that complain that you'll never have your car going.
graeme jackson


You'd want to keep the cam in place if for nothing else to drive the oil pump.
David Billington

I'm getting more and more the urge to try this conversion.
But unlike Prop I will do it with a spare engine and then swap. Yes Prop I know you where forced to, because of your crankshaft, but we started almost at the same time and I've just passed the 5000 mls mark...
Alex G Matla

^^^ owned

What - you mean one of these?

Dont need a dizzy as you have a crank sensor. Cam is machined down to a rod to drive the oilpump.

You can see it in the photos...
Toby Anscombe

Toby, I reckon at the minute it's a dead heat between you and Prop as to who finishes their engine first!

Looks well smart, that is the only other mod I'd want to do to my 1380.

Hey Alex,

Sorry for the confusion...I know hard to belive, Id be unclear...LOL But Im doing a completely new engine not the current one Id keep this one for the midget and the Beemer head in a bug eye sprite

500 miles??, Buddy you better get driving or ill pass you by the end of sept. LOL


I thought there was someone on here that built on, I forgot it was you....You havent fired it yet? I guess it is a race... how far off are you?


Have a great time, looking forward to hearing of your adventure... yeah My mother is a clean freak also, she buys so much tolit bowl cleaner they had to replace there 15 year old tolits last year because she wore the porclein off the inside of the tolit bowls


To right Tarq, I remember someone saying a few months before Spridget 50 that with a bit of work Toby would be going in his Midget! LOL When I saw it I thought he would be very lucky to make Spridget 75 but you never know.
Robert (Bob) Midget Turbo

LOL Prop - Alex has done 5 THOUSAND - not 500 :P - including a visit to the UK ...!!!!

LOL 15 year old loos is quite old though ... ;) I think it is something that is put out of sync when you have babies - something that I will never find out!

Am looking forward to the trip - honestly :) I'm sure you'll hear what a scary and mad person I am from Arie, without me saying anything ...............

Bob - I guess you missed the post about bring the midget on the 26th and autotesting it ...?! After all, as is well proven on the website - I went to the drive!

Didn't miss it Rach but I had a problem. I am trying to sort out my modified clutch. As you will remember before I went on holiday I had someone do a big machining error that cost me my Toyota conversion backplate. I have been trying to fabricate a new one of thosed along with modifying a larger clutch and plate.
I am nearly there now except with the engine installed for a second time it will not turn over very well? I suspect the stater position is to tight to the flywheel but am not sure.
Bob Turbo Midget England

Well, that's alright Bob - you can always autotest the MGA :)!

Bob - fire me an email with the details of your back plate - may be able to help you out there

This thread was discussed between 27/08/2010 and 01/09/2010

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