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MG Midget and Sprite Technical - EFI 1500 Manifold mk3

Hi folks, hope you are all well.

It's been a while, but as ever I have been working away, dreaming up new and ever more complicated ways of extracting a few more horses from my 1500.

Probably only exciting to the engine geeks like Willy and Peter Burgess (!), but I have a new inlet manifold that is slowly coming together.

- Aluminium (current one is stainless)
- Plenum sized increased and now a "tapered" design to try to help improve overall air flow as well as the distribution to each cylinder.
- Runner length increased (I re-did the calcs and they should now be better tuned for a high 5s rpm peak).
- Split design, so the plenum can be removed from the runners/manifold.

Still lots to do, but the basic shape is there, as you can see.

Cheers,
Malc.






Malcolm

That looks awesome Malcolm. How do you find the space for it in a 1500s engine room?
Who's doing your TIG welding? It looks beautifully executed. I haven't done any for about ten years but even in the day I'd be pleased with the look of that.
I like the colour of the stain, but are sure it's right for aluminium?
Haha.
I'm sure you'll tell us what happens when you have it fitted. Can you recurve your fuelling and ignition without too much hassle? And do you think you'll have to play with the exhaust length and volume to scavenge the additional gasflow?
Nice job so far.
Greybeard

Hi Grey, glad you like it.

Plenty of space, it's no more bulky than the original setup with manifold, big carbs, air filter etc. Also, I don't have the bumper girders, so loads more room.

A mate at work does the welding, he used to be coded in every type/material/level. So he is pretty handy. Even with our crap TIG set, wrong gas and any old alloys to weld he makes it look easy.

Remapping fuelling is fairly easy. All done via laptop/Bluetooth to the ECU. Then verified on the rolling road.

Exhaust is my own design 4 into 1 manifold into an exhaust with twin straight thru silencers. I have a wee mod to do to the collector as recommended by Willy. But it *should be up to the job already.

Aim is for over 110hp :-D

Malc.

Malcolm

Malcolm,

Years ago I was told about a local guy in the AH club that was trying to do some Al MIG welding with a low end MIG on a big Healey and wasn't getting on at all well, the MIG was set-up with a soft wire liner and suitable gas but he couldn't make it work so he called in a mate that worked as a welder at RR or British Aerospace and he did the job fine with the kit.

Wrong gas? what were you using?

Manifold looks good, it should be interesting to see what the results are.
David Billington

Hi David,

TBH, not sure what his gripe with the gas is. He seemed to think it was an Argon + other gases mix. But I've just had a look and it's straight Argon, so should be OK. He is one of these people that is a bit of a perfectionist/nothing is every right. Maybe a bit of Helium in there would cheer him up! :-)

Malc.
Malcolm

Malc --that little mod we spoke of is all about scavaging--it's as you say only a little job but important that it gets done-----12" min if i remember X whatever dia. it was--can't remember what we worked out there but I'm sure you have that down somewhere
cheers
willy
Something that'd interest you--
We had our annual historic meeting here at the weekend and a fella bought his 454 Corvette over from the mainland, He's raced it here (Aust) and in the USA with heaps of wins---Met his match here though, a mate here runs a V8 injected MGB and finished in front of the Corvette all weekend---I reckon he got a bit of a surprise how well the B went, saw him having a good look at it in the sheds.
William Revit

Gonna try and get the exhaust off this weekend Willy, then I will have a measure up for some bits to do as you say. 12" x 2.25" IIRC.

Did you do the engine on the B? Was it a Rover V8?

Cheers,
Malc.
Malcolm

12"x2.25"--yep that's it
And yes 3500Rover--on the outside anyway,you'd never know what was inside it, he does his own engine (does big diesels for a job)-
some pics for you to flick through-
If you click on the pic of the red Corvette and open that group, the B is in there(group Lb-S + invited)

There are other MG's in the regularity group, the only one there I play with is the green MGA

https://www.matthewbissettphotography.com/baskerville-historics-2023?fbclid=IwAR1Y6UD92z7hEOLkuvxx3U-kVP0NcdFORAdoCn2GL9A9AMZTTlHmgJLRlrU

willy
William Revit

Cool pics. There are some superb looking cars in amongst them all. The Mazda and the Merc in the Historic Sedans :-o Brilliant!!

Cheers,
Malc.
Malcolm

That Mazda is on a spaceframe chassis running speedway style Willwood hubs/brakes and a Hallibrand quickchange diff, all fibraglass body----good car
The killer car in that category is the Gowans Celica built on all Lola F5000 running gear--very fast car
The best race of the weekend is usually the highly competitive Kit Ellis memorial race for Minis, they really get stuck into it- I missed that this year, I went Saturday and it was Sunday----bugger--Kit was a good friend and a real racer, His old Mini, now raced by his nephew is still super competitive , it's the dark blue one with yellow roof and bonnet stripes

https://www.youtube.com/watch?v=LLt1BqLCask
William Revit

Slowly chipping away with it and almost there! Hopefully be done by the end of the week :-)


Malcolm

Looking good Malc.--What's the plan for holding the fuel rail/injectors in place.--just interested
willy
William Revit

I plan to weld a wee "pad" onto the runners and simply hold it with a couple of P-clips. It has worked fine in previous iterations, like in this pic but more refined!


Malcolm

Mmmm--I think I'd be going something a bit stronger than P clips, specially if they're going to be mounted on that side of the rail---On the other side(pulling) they might be ok but I'm a bit worried that with 45psi or so fuel pressure, the P clip could give in to the pressure---It's only got to move not much and the fuel will spray out like a garden sprinkler from the top O ring and up she goes--
The reason I asked was--
Down at the Historics at Baskerville a month or so ago a guy went past me in the pits with fuel running out the bottom of the engine bay of his BMW--pulled him up and we had a look and his rail bracket had moved just enough to spit no1 injector o ring out--he was very lucky it didn't go poof, the only thing that saved him really was a large heat shield he had that stopped it spraying everywhere where the hot bits were waiting.-
willy
William Revit

Thanks Willy, always appreciate your advice.

It's worked for the past three years, but it's like the stock market I suppose - past performance isn't an indicator of future success! Always room for improvement, so there we go, clips "pulling", with a nice fat pad and spacer under it all.

I will obviously do the screw up tight ;-) no socket/spanner handy.

Malc.





Malcolm

It (pretty much) fits!!!


Malcolm

All looking a bit special Malc- Nice job
William Revit

Hi Malc
have you done a spear point where the 4 becomes 1?
Peter
Peter Burgess Tuning

Spear point - check ✅


Malcolm

Getting the collector off the manifold was an absolute pig and I have some repair work to do.

On my way to Anglesey in the summer I overtook a cyclist, when straddling the cats eyes, there was a bump/dip and the exhaust smashed into a cat's eye with one helluva bang!! I was going a reasonable lick, 50 - 60 mph, as it was a long straight and quiet road so I didn't have to slow down.

It hit it so hard it shifted the exhaust as it was banging on the chassis for the rest of the trip!

Couldn't do it again if I tried!! But made a right mess!

Malc.



Malcolm

Willy... This exhaust collector feels to me way over the top, but I trust you know what you are on about! :-s

(And yes... I know for scientific thoroughness I shouldn't go changing two variables at once, but I can't be popping up to Peter's place every other weekend! Although the inlet manifolds would be pretty easy to change and do a back to back... Hmmm...)

Cheers, Malc


Malcolm

Nice bench....
Greybeard

Kitchen... Not garage! ;-)
Malcolm

From the magic of my 'pooter I get around 15" all up from the merge point to the start of the reducing--If you're stuck for room you could cut it shorter by a couple of inches if you really had to---but if it fits up ok as is I'd be leaving it as is---I can feel the power dripping out of it from here---
willy
William Revit

15 is a bit optimistic, it's 12" give or take.

- 3" bit with lambda boss
- 1" around the centreline of the elbow
- 6" straight bit
- 2" before reducer kicks in.

Should be plenty of space, it just flaps around underneath the car!

Cheers,
Malc.

Malcolm

Perfect--
My apologies, I'd blown the pic up to get it to 2 1/2" dia. to determine the length instead of the 2 1/4" that it is which threw the length out--my boo boo--it'll be good.
William Revit

Youre having a "flexible" bit in your exhaustpipe Malc?

Eventualy I had one in my 1500 pipe as stress caused cracking on mine.
Think mine was positioned under the lH footwell/seat...
A de Best

This thread was discussed between 02/11/2023 and 16/12/2023

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