54 replies to this topic

[MRA]

200hp is more than possible on a 5port and single SU. Leyland did it in the mid 80's with the Group A Metro Turbos. With the advances in turbo, cam and porting improvements over 30years later it should be somewhat easier.

Phil.

It was my understanding that Ian Hargreaves (Avonbar Racing)was responsible for the group A turbo challenge output..... but totally agree with what you are saying..

Edited by MRA, 17 March 2017 - 11:25 PM.

[Turbo Phil]

The group A engines were built by Howley racing. I was lucky enough to pick one up years ago from Phil Hepworth who was responsible for building them.
The Metro challenge race series is completely different to the Group A Metros which were works cars run by Leyland in the touring cars series.

Phil.

Edited by Turbo Phil, 18 March 2017 - 08:30 AM.

[MIGLIACARS]

Is the Patrick watts metro engine of which he races today the same spec as the original group A metros

[jt19]

You can get close to that without a turbo. Just a 16v head......

Bottom end and box will be the same specs though.

Maybe but what rpm and how much torque?

[mini_mentalist_chris]

I'm getting the bits together for my turbo engine at the moment. I'm building it as a weekend car, with the intention of doing some track days. It will be a 1293 with a GT1752, and I'd hoped for a figure between 180-200 bhp. I'm guessing I'd need to be running about 18-20psi to achieve this. Would the cast pistons be up to the job of an occasional track day, or would I need to go forged?

[mini13]

good cast ones will be ok at that, certainly cast omegas, or metro turbo pistons would be fine

[MIGLIACARS]

I can vouch for the die cast omegas at 170whp,   but it doesnt matter how good the pistons are if the fueling is wrong

 

bang

[mini_mentalist_chris]

Cheers guys, I had originally planned to buy cast omegas, so will stick with that decision. Will be making sure I have a wide band lambda system in place for the fueling for sure.

[HUBBA.HUBBA]

Normally just a 1293 will do it. You can over bore to what ever size you want. But you don't need the extra cc's to make the power

 
But going bigger does pull in the torque better
 
Also its my experience that the Omega cast pistons are good for at least 16psi long hard thrashes, but in reality if its a road car, your long hard thrashes will be somewhat shorter than they used to be so less of an issue, I also don't bother with a center main strap.
A 5626 gearcase is a must as is a four pin diff or better, on my first turbo Mibi in 1986 I killed one diff pin in under a week and removed the next one just before it destroyed itself in under 3 days, there is a picture of this one on here someplace...
 
Don't forget brakes and suspension upgrades, ie rose jointed tie bars and bottom arms if set up correctly will eliminate any torque steer up to about 200 at least

Why not bother with centre strap?

[Steve220]

Normally just a 1293 will do it. You can over bore to what ever size you want. But you don't need the extra cc's to make the power

 
But going bigger does pull in the torque better
 
Also its my experience that the Omega cast pistons are good for at least 16psi long hard thrashes, but in reality if its a road car, your long hard thrashes will be somewhat shorter than they used to be so less of an issue, I also don't bother with a center main strap.
A 5626 gearcase is a must as is a four pin diff or better, on my first turbo Mibi in 1986 I killed one diff pin in under a week and removed the next one just before it destroyed itself in under 3 days, there is a picture of this one on here someplace...
 
Don't forget brakes and suspension upgrades, ie rose jointed tie bars and bottom arms if set up correctly will eliminate any torque steer up to about 200 at least

Why not bother with centre strap?

I was always told the centre strap is for high rpm configurations.

[MRA]

 

 

Normally just a 1293 will do it. You can over bore to what ever size you want. But you don't need the extra cc's to make the power

 
But going bigger does pull in the torque better
 
Also its my experience that the Omega cast pistons are good for at least 16psi long hard thrashes, but in reality if its a road car, your long hard thrashes will be somewhat shorter than they used to be so less of an issue, I also don't bother with a center main strap.
A 5626 gearcase is a must as is a four pin diff or better, on my first turbo Mibi in 1986 I killed one diff pin in under a week and removed the next one just before it destroyed itself in under 3 days, there is a picture of this one on here someplace...
 
Don't forget brakes and suspension upgrades, ie rose jointed tie bars and bottom arms if set up correctly will eliminate any torque steer up to about 200 at least

Why not bother with centre strap?

 

1) Never needed one.

2) They are really suited to higher revs 8k+

3) Most (although I can machine my own) are not of the correct material grade or quality of manufacture.

4) There are processes that can be applied to the block that will make a CMS redundant for 95% of Mini engines

5) You would need to have the cap machined to suit the strap, ie both surface ground to get 2 flat as possible surfaces, not possible with milling even on a brand new machine.

6) You would also need to have the block and caps line bored to remove any possibility of distortion.

 

It's been proven that most move in use which is potentially very bad, so sticking with standard on my engines unless somebody wants one then I would of course supply one, I have a few in stock made with S156 Steel with SAE8 bolts (not the ISO8 which are completely useless in this application and not even close to standard.... 

 

But like all things Mini, it's a personal thing and people will continue to request them for engines that only make 85bhp and never go over 5500 rpm's

[MIGLIACARS]

 

 

 

Normally just a 1293 will do it. You can over bore to what ever size you want. But you don't need the extra cc's to make the power

 
But going bigger does pull in the torque better
 
Also its my experience that the Omega cast pistons are good for at least 16psi long hard thrashes, but in reality if its a road car, your long hard thrashes will be somewhat shorter than they used to be so less of an issue, I also don't bother with a center main strap.
A 5626 gearcase is a must as is a four pin diff or better, on my first turbo Mibi in 1986 I killed one diff pin in under a week and removed the next one just before it destroyed itself in under 3 days, there is a picture of this one on here someplace...
 
Don't forget brakes and suspension upgrades, ie rose jointed tie bars and bottom arms if set up correctly will eliminate any torque steer up to about 200 at least

Why not bother with centre strap?

 

1) Never needed one.

2) They are really suited to higher revs 8k+

3) Most (although I can machine my own) are not of the correct material grade or quality of manufacture.

4) There are processes that can be applied to the block that will make a CMS redundant for 95% of Mini engines

5) You would need to have the cap machined to suit the strap, ie both surface ground to get 2 flat as possible surfaces, not possible with milling even on a brand new machine.

6) You would also need to have the block and caps line bored to remove any possibility of distortion.

 

It's been proven that most move in use which is potentially very bad, so sticking with standard on my engines unless somebody wants one then I would of course supply one, I have a few in stock made with S156 Steel with SAE8 bolts (not the ISO8 which are completely useless in this application and not even close to standard.... 

 

But like all things Mini, it's a personal thing and people will continue to request them for engines that only make 85bhp and never go over 5500 rpm's

 

I to have never used them for the reasons above its not easy to improve on standard factory items they were not idiots you no..

[mini13]

yep, in my opinion, std caps or steel ones with a 4 bolt centre,

 

more important in my opinion is a line hone.

[Jarvey]

What about gearbox mods / upgrades?

 

Going from a standard A+ to 200bhp would need some serious help surely?

 

What have you guys done to maintain reliability and driveability?

 

Obvious things like SC gears, RTS clutch, pinion bearing housing ... what else?

[mini13]

you'll be supprised how styrong the std box is,

 

you will need a x pin diff, helical gearsets wil take circa 150 hp, for the figure your talking most people fit the minispares evolution sc gearset, quite a few people are running helical drops still at 200 hp as you get a quiet 4th gear for cruising, personaly I run the taper bearing minspares ones, and find them not that noisy, but it varys car to car.

 

not many people run the pinion support, another thing, use a casing that has three holes for the pinion bearing block, not 4, as the 4th one can cause cracking.

 

clutch wise I would always run an RTS these days ( unless the car was a track screamer and would beinifit from an uber light flywheel), so much less hassle and more user freindly.