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MG Midget and Sprite Technical - Turbo Midget project
|Hi, My wife and I have had our 1971 midget for about 6 months. The motor is getting a little tired so I figured if I am doing a rebuild, I am going to turbo it. I have done some research and seen what some have done. I am going to use the basic Metro turbo setup. Looking at using the T25, custom elbow on the carb to push it back to clear the bonnet and some type of intercooler. That's abotu all I have planned out. Need to get the bits and do the motor. Any suggestions, pitfalls anyone has would be great. Thanks|
|Here is a picture of mine when I first did it a year or so ago, I am at present changing things because the standard clutch could not take the power and I have now removed the engine to modify and fit a larger stronger clutch. Whilst the engine is out I am tidying everything up so it looks a little more appealing.|
I am a member of the MGCC and do a lot with the Lincolnshire Centre (Not too far from Suffolk? ) however if you can not get to any of our events then please do not hesitate to contact me via email for information that you may need.
So the first 2 things I would definately advise is, build your engine with low CR (About 8 or 8.5 to 1) also fit an uprated clutch, if that is beyond your ability to do then Peter May will machine your flywheel and sell you the clutch to suit.
rjwelchmidget "at" aol.com
|Robert (Bob) Midget Turbo|
Do you have a picture of the T25 elbow,I have heard of this mod but not seen one and who sells them?
I did a bonnet bulge as I like the look.
If you are having your engine rebuilt then this is an ideal opportunity to get it right the 1st time round.
Go for min rebore i.e. 1293 would be ideal,
11 stud head not 9,
Strapped hardened and balanced crank a must,
I fitted P.M. lightened steel flywheel and 7.5 rally clutch as Bob said this is well worth doing to save problems in the future and now if needed it will rev off the clock!
I learnt all my Turbo info from the mini boys, there are plenty of mini turbo internet sites out there to give you all the info you need.
Once your engine is rebuilt avoid temtation to raise the boost if you want your engine to last 10psi is plenty (metro turbo would have been standard 4psi this was to protect the weak metro gearbox)
Bob might disagree with me regarding boost as I know he runs higher psi
If you are buying a second hand turbo make sure there is no play in spindle as this could cause you big problems to your new engine if that goes bang !
The only thing I havent done is fit an intercooler yet but will keep you posted as this is to be my next project.....Brad will be along shortly.
Will it be done for Midget 50 ???
Bob looks like the forced induction club is getting bigger!
|Thanks for the info guys. The plan is a new or rebuilt turbo. I am very much aware of the pitfalls of used turbo's. I am hoping to pick up a T25 with the T3 flange, so that it bolts straight to the the manifold. If not there are plenty of adapter out there for them. For the carb extension, I am going to have to fab something up, I haven't seen one for sale yet. I am more into the sleeper look, so a power buldge doesn't fit in. |
The plan is to use the 1275 GT motor out of my wifes project mini. Take it in and have it bored and whatever it needs done. The plan is new low CR pistons. I am prefectly capable of building it up, just not the machine work, even though I am used to motors that are a little larger.
The clutch sounds like an excellent idea. Are you still running the stock 4 speed? I am assuming a machine shop can do the 11 stud conversion. Any reccomendations on where to take the motor for the work?
Bob, we would love to get more involved with one of the clubs. Usually our biggest problem is getting a sitter. 2 small kids and a midget, dont go together. A week or so ago, we saw a group of MG's at Cambridge Services, looks like they were out on a cruise.
I have been doing some reading alot on the mini forums about this. Of course, there is more room in the Midget to set this up.
What is everyone running for disttibutor. Toying with the Megojolt thing, just not sure yet.
I guess the first thing is get the motor build and parts collected.
I have a year till Midget 50, correct? Should have it done in time. Once the parts are collected, it wont take long to setup. Just money,
|LOL - 11 June next year, so yes, just under ...!|
If it was on the Sunday, then it was probably for the Anglia picnic day at Anglessey Abbey - but, wasn't my "cup of tea" (plus I was up to my elbows in oil and grease at the time!)
As for work - it sort of depends which end of Suffolk you are in?
You say you intend to use the engine from your wifes Mini project, have a look in the archives its not an easy job to change a transverse A series engine into an inline engine. There are many differences in the block.
"Have it bored and whatever else needs to be done" its a lot, in fact I dont think it can be done economically.
|M J Pearson|
|11 June, plenty of time!!|
Acually it was a friday. They then headed up the A14 and got onto the M6 (I think). I am down in Mildenhall, so northwest suffolk.
So your saysing just pick up another Midget block and start from there. I would assume most of the internals (pistons, timing set, valve train) are interchangable between mini and midget. I have o problem picking up another motor. I don't want to tear the motor out of the car without having a replacment. Can't have too many cars in pieces. Plus would be able to drive it. So time to look for another engine.
|Jesse, two tips:|
assume nothing, and get a copy of Vizard's A series book; there are many detail differences between different years and models of 1275 engines Mini / Midget / Marina / Ital. Some parts will mix and match, some won't.
|Jesse - Midget, Minor, Ital or Marina.|
Later Marina or Ital blocks with the A+ strengthening ribs would probably be your ideal.
There are a myriad of minor issues with which bits fit which block/crank/flywheel - but whilst pistons/rods/valve train etc are all common to the mini, you do need the crank to match your block for an in-line setup.
Random ebay search shows up 220632393774 which would be an ideal starting point. The ital flywheel/clutch is *huge* so you'd need a midget flywheel aswell - which needs a small amount of machining.
some pics of my build of NA 1380 based on Marina block...
|Dean Smith ('73 RWA)|
|Turbo A-series is neat for a road-going car - plently of torque without all the 'fun' of long-overlap cams and high-lift rockers.|
I hope Tamsin won't mind my saying that she wasn't overly impressed the first time she drove a K Series Midget; but then we found out how much boost she'd been using on her A Series (adjustment behind the dash)...(!)
|So what should I expect to pay for a motor like the one on ebay?|
|on ebay seem to be 125 to 150 but sometimes you get lucky and they go for less.|
|Similair looking Marina one went for £80 (220623400938)|
You need to consider you're buying little more than the block and crank in reality. You will need Midget/Minor front and back plate aswell. (the marina/ital engines mount in the middle of the block - minor/midget via the front plate).
|Dean Smith ('73 RWA)|
Jesse, fit a Ford clutch, Peter May can lighten your flywheel & drill for the new clutch.
I would get your head opened up too, Peter Burgess did a fine job on mine & increased the Turbo head from 17cc to 25cc which has brought the CR down to 8.5:1
I will be Megajolting my new engine & will aslo be using a wideband lambada on the aux i/p to help fine tune the mixture.
Of course you can just bung in a standard Turbo motor, but thats no fun really is it.
I'm still mulling over the intercooler & oil cooler fitment.
|Brad, Are you running dished pistons? Or just the larger chamber heads? How is the best way to contact these guys when I am ready? I will just start collecting parts. I have the turbo intake, carb and plenum. I also have the exhaust with the T3 on the way. More than likely wont use the turbo though. I guess the next thing is source the motor then. |
Thanks for all the ideas so far. Gives me a direction to work.
Agree with most of the previous comments.Do put an intercooler on if you're thinking about serious boost (10psi and up) Also megajolt to map the timing.DO get it set up on a RR by someone who knows about these funny old motors.I didn't the first time out and blew a piston.Think about a T3 for max power but lots of lag,or a T25 for good low speed grunt.The ultimate is a GT1752 off a modern Saab.Have fun!(this is mine)
I forgot to ask you on previous thread if once the front mounted intercooler was fitted that you have any cooling issues (air flow to rad) as I have now found a 600mm x 14mm universal intercooler that I think will do the job.
So I now have a brand new Renualt 5 intercooler going very cheap!surplus to requirements.
|Plenty of comments which is nice to see.|
I think boost of well over 10 psi is a must. With correct CR and ignition the engine flies. Also it is not too dangerous as with the acceleration been so fast the excess boost is only on full song for a few seconds before your desired speed is reached.
The Marina crank and block is a good idea. As stated the rear of the crank on the Marina is slightly larger in diameter than the midget thus the Midget flywheel requires slight machining to fit the crank. My bottom end is also centre strapped.
Do not bother with the Mini/metro block too much of a pain to modify.
The benefits of the Turbo head are the exhaust valves which are sodium filled. These can be purchased and fitted into a normal A series head casting so no problems there.
Metro Turbo piston are best value here as they are probably the best quality pistons available. If using the Marina crank then Marina or other 1 3/4" rods are required because the big ends are bigger than the standard Midget (Could simply use the rods from the Metro turbo
I use an alpha mappable ignition which I think is a must.
Originally I ran my turbo with about 8.5 CR, basic 6 psi boost non ported head. On a rolling road shoot out it registered 113BHP at a very low 5500 RPM compared to an ultrahigh revving normally aspirated A Series that saw about 118BHP at somewhere in the region of 7000 to 8000 RPM Its called Torque :)
I also have an intercooler
The man I have used for many many years of A Series mods works in Lincoln and is called Mike Barret, has plenty of experience with Turbo A Series and does a good job website here http://www.mberaceengines.co.uk/
|Robert John Welch|
My post above reverted to an identity I used to use a good while ago??
Did't say I had a turbo! LOL
|Robert (Bob) Midget Turbo|
|I'm using dished Omegas & larger chambered Turbo head. |
Having been through quite a lot of clutches previously & carbon bearings, the Ford one has lasted 5 years now with no problems on a high reving 1380.
|To echo Brad I think to get a low CR it will be necessary on all engines to enlarge the head chambers, what is the largest dish on the omega range Brad?|
|Bob Turbo Midget England|
|Apparently it does that Bob!|
Mildenhall is not hideously far away from Milton, so, if you got the chance to go to one of their Natters and speak to Bruce, he'd likely know a really good workshop down there that does that work you need to have done. They are the first Wednesday in the month.
i'm on my travels again at the moment so don't have a lot of info at hand.
However i had a target CR of 8-8.5:1, wanted the pistons to be near flush to the block & have most of the squidge in the head rather than the bores, & didn't want a CR spacer between the head & block, so i basically worked out the build in reverse on paper first.
Theres a mini engine CR calculator knocking around on the web which is ideal for this.
|Rob, what are you looking to get for the intercooler? May be interested. |
I will have to see what my work schedule looks like. I am an early to bed person, as I get up early. Try and make it over to Milton Keynes.
Any suggestions on transmission, or keep the original?
No overheating problems,but I do run a thicker core radiator.also the large intake below the grill ducts air past the oilcooler and up to the rad.
I would argue for forged pistons if you plan big power,but solid stainless exhaust valves-the sodium cooled ones are v. expensive,have thicker stems,and being 2 piece,the head can drop off!
|Thats what I like about this game:|
Ask 10 people how to do something and you will get 10 different opinions and all will do the job!!
Brad I am a believer in squish and also subscribe to the decked block theory. however I thought the Omega only did an 8cc dish? I am not the expert in this field and leave such decisions to M Barret!
|Robert (Bob) Midget Turbo|
Buy me a drink and its yours, when ever your passing DY6 or if you go to any meets I could meet you there.
Transmission..I have run the turbo with a standard ribbed 1275 box and Ford type 9 and they are both up to the job as long as they are in good fettle, down to preference I think.
Thanks Steve, hopefully two weeks and i will have an intercooler fitted in front grill,I presume a good amount of air will pass through the intercooler and into the rad, in the winter I had trouble getting up to temp as I have removed stat and bypass hose so hopefully it will be ok
|Bob, Omega race pistons come in 7cc and 11cc dish - maybe others too|
|Rob, I may take you up on that offer. You are Stourbridge direction right?|
Rach, is Milton, over near Cambridge? If so, that is an easy run. Who meets out there?
I picked up a motor today. It was the ebay auction Morris Ital 1275. What don't I need off the Ital parts that I can rip off and get rid of? Is there a decoder for the engine number?
|The Ital prefixes are usually 12V639 or 12V923; what do you mean by decode?|
|Milton's just off the A14 at Cambridge, so yes, very easy run from Mildenhall area ...!|
Having said that, there was only a couple of us who are into "playing around" with our cars, so, probably better to try and check first .... LOL I'm still on my "I'm not making mine into a K" kick, but, I'm now saying that, well, if I don't go to Canada .....
The other possibility is that Bob sometimes comes down to the natter at Terrington - so you could perhaps sort out a day for that ...??????????? That's a pretty easy run too - about 40 minutes up Prickwillow, A10 to A47, then just off there a couple of miles.
|Here is the car.
|Yep, the prefix is 12V923 EH7. That's pretty much what I was looking for.|
When you get together, shoot me an e-mail. Even if I dont bring the car I can bring the brood with me. To actually bring the car we need a baby sitter. Dont feel like the ticket for children loose in the back.
This thread was discussed between 05/07/2010 and 13/07/2010
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