Forged or Cast needed?
Turbo Mini Forums

Hi, had a search but cant find the definitive answer.

Is it worth spending the extra £200 on forged pistons or will cast be ok for the job.

Im planning on building a 1380 n/a engine, however it is going to rev pretty high as im planning on using a kent 310 cam, hence my question.

Cheers, Oli.

cast should do it. I had a 1071 overbored to 73.5 mm using powermax pistons (cast). That saw 9300 rpm from time to time. That said, the pistons speeds will be higher with the longer stroke of the 1380 compared to my 1191, but I would still go for cast pistons.

Why are you using such an extreme cam? what kind of useage will the engine see?

Cheers.

Trackday car basically. looking for around 120-130bhp, so a lary cam is pretty much necessary, however i am looking at using a 296, or even a piper 649+.

well I was very happy with the STR930 miglia cam in my 1191 engine. It pulled nicely, and had a good top end. Think I would rather choose that compared to a maybe too extreme 310 cam. Listen to Bill Sollis advice on the cam for the 7 port engine in the new film from minifilms.

For this kind of hp, you really need a quite extreme head aswell.

I'll have to order that then, as i am planning this around a 7 port head, 37/31mm valves, going to be pretty hectic, hopefully.

Edited by Oli on 3rd Dec, 2008.

he didnt mention the STR930 cam for a 7 port, but he thought the 310 cam was too much for it. It made it hard to drive.

ahhhh, might have to go back to the drawing board on that then.

Do you know what the power band is on an STR930 is?

Edited by Oli on 3rd Dec, 2008.

The head on my 1191 engine was not extreme enough to give max power, so that had max hp at 7000, but kept on fairly flat after that. I have not got knowledge on where it is in the miglias, but I would suspect around 8000-8500 rpm.

8000-8500 sounds about right, on utlimate mini performance bill sollis says his miglias never below 6000rpm on the track.

Utter bollocks about 310 cams being too much. I drive one on the road. It pulls from 3200 in 4th gear all the way to well over 9000rpm.

Paul

I seriously doubt it!

Funny you should say that i have just been reading an old thread of yours where you mentioned this, and about the salisbury diff.

Can i ask if you run cast or forged pistons?

You only need cast pistons for n/a really. Ive run them for 9 years although Ive just splashed out on new forged ones because theyre lighter

Paul

I seriously doubt it!

Brilliant cheers, ill probably just go cast, as im not on a weight saving crusade like you lol.

Cheers

Hi there,
I run 300 scatter cam and i find it is just fine in my 1380 n/a, but it is a 5port head i run. it pulls well from under 2700 ish and is driveable under that too.
Just to add, this is my road car which sees about 8-10000 miles p/year. The bigger cc engines tend to be able to come on cam a bit earlier, so the lower end does not suffer so much.
But 5 port is as far as ive been, so no help to you there, but i was just trying to draw out the wealth of expertise (and opinion ) in the lads on here.

I reckon 310 is no problem at all for a trackday yoke.

Regards
Colin

EDIT: oh yea, cast! defo! (read it back afterward and forgot the Q:$)

Edited by 1972-ANGUS on 4th Dec, 2008.

If your going for cast, consider the Hypatecs from Australia.

The 73mm (1360) and 73.5mm (1380) ones seem a really good design (a few people on here have bought them, inc, me) and are considerably cheaper than anything you can buy in the UK.

Schrödinger's cat - so which one am I ???

I have reservations on these Hypatechs untill they have been tried and tested. Any one had them in an engine abused them and stripped the engine down yet?

Cant help but hear the phrase 'you get what you pay for' in my head.

Just me being over causious

Powermax pistons are cheap, and have been around for years, basicaly AE's performance pistons. Johnspeed Minis aslo do a piston that is Identical, yet they state that they are not, but do not say why?

If the budget can streach, I would buy Omega cast pistons with out hesitation.

Edited by Sprocket on 4th Dec, 2008.

Schrödinger's cat - so which one am I ???

A set of forged omegas took 5000 miles of abuse (fun in the rush hour on the country lanes against idiotic bmw drivers) Only reason i dont have them any more is because i dropped a valve through one, so i put in a set of cast pistons in.

Although i do think about winding it upto such high revs now.

Pistons in general are waaaay cheaper in OZ than here, although this may only stand true for the Yanky V8 stuff. Infact I can't think of seeing pistons over there for the price people pay for decent forged ones here.

OMEGA cast pistons WELL proven and hard to beat at £280 inc delivery including rings, there well priced

but ........if you have the money ?

I seriously doubt it!

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE

Racer's what its ment to be, but it'll probably end up being a bloody heavy mini, compared to everyones on here! (I like my creature comforts lol)

Edited by Oli on 6th Dec, 2008.