11 replies to this topic

[NDT]

I'm soon going to be building my engine - probably a 1380, with a (lightly modified) MG Metro head and an HIF44.

This will be a weekend only car - but I'd like it to be reasonably useable.

The complication is that I will start off normally aspirated but may well go turbo later on, so need a cam that works for both options.

 

Anyone got any thoughts?

[Ethel]

Not anything with significant overlap - plenty of choice from road spec cams that have been designed with emissions tests in mind.

[Turbo Phil]

As already mentioned above you generally want minimal overlap for a turbo application. The Kent cams KC500 works well in a turbo motor and will still give decent performance in NA use to.
If you’ve not bored the block already I would avoid 1380cc. The larger bore makes it harder to get the compression down to a suitable level for turbo use and the best quality turbo pistons are available in +0.020” and +0.040”.

Phil.

[NDT]

thanks both

[AP2020]

1380 turbo's Mini's make for good road cars, as the torque comes in sooner you don't need to rev them everywhere, you also don't need to grab gears all the time, as above getting good pistons may be a challenge, but Omega's if you can get them are great pistons light and strong. 

 

Remember:-

 

If you want to go for high boost over 16psi forget 1380.

As above wide cam durations just mean you'll be revving the nuts off it to get anywhere.

The larger the engine the less of an effect the cam duration has.

Use a higher final drive and a good clutch, this way you can control wheel spin, so a SCCR kit is pretty much a must have.

Diff ? a minimum of a cross pin is required, ATB or LSD would be better

Get rose jointed bottom arms and tie bars, as this if set up correctly will pretty much remove any torque steer.

Brakes vented fronts and 4 pots would be my start point.

 

I currently run a similar spec as above with 225/45-13 proxxes and 285mm discs with 6 pot calipers I've built mine for track but also to be road legal.

[OzOAP]

CAM6648 MG Metro is good in Turbo application.

[Turbo Phil]

CAM6648 MG Metro is good in Turbo application.

Yep, and available from Kent as the KC500.

It’s overlap that’s the issue with a turbo as the pressure in the exhaust manifold can exceed boost pressure which causes reversion of exhaust gases into the cylinder. Fitting high lift rockers can also have a negative effect as it increases lift at all points which includes the overlap period.
By using a better flowing manifold and less restrictive turbine and improving the ratio between boost and exhaust back pressure the more “cam” you can use.

Phil.

[OzOAP]

CAM6648 MG Metro is good in Turbo application.

Yep, and available from Kent as the KC500.

Ah ok. I don't use Kent cams

[NDT]

Thanks guys.

I'm not after crazy power.

I'll see whether the engine actually needs a rebore then decide what capacity to go for - it's an MG Metro engine that hasn't run for 30 years...

[AP2020]

Thanks guys.

I'm not after crazy power.

I'll see whether the engine actually needs a rebore then decide what capacity to go for - it's an MG Metro engine that hasn't run for 30 years...

 

Then I would suggest 1380, low boost, so slightly higher than normal CR for a turbo, no intercooler, as your low boost won't need one, you will need a minimum cross pin diff and oil cooler, try Ian Hargreaves at Avonbar Bar racing, his engines are bullet proof and his knowledge is legendary .... don't go cheap on pistons and an ECU for the ignition makes a much better and more driver friendly road car, fit a 3.11:1 FD or higher ratio, 2.95:1 etc even 2.76 will work well with this combo, and don't forget breaks and suspension...

[DeadSquare]

Thanks guys.

I'm not after crazy power.

I'll see whether the engine actually needs a rebore then decide what capacity to go for - it's an MG Metro engine that hasn't run for 30 years...

 

 

Go for the minimum re-bore............blowing it will compensate for the smaller volume.

 

Blowing it also makes more heat in the same space, and from about 60 years experience of lightly blowing engines, if you get the metal between the bores too thin, it seems almost as if there might be fractional movement in the block or something, which sometimes leads to gasket failure between the bores.

[NDT]

thanks both. Will know more about the state of the bores after this weekend.