Max boost on a stock A+
Turbo Mini Forums

How much boost would be the limit for a stock bottom end on a A+ 1275?

And how much power could be made with a stock head?

Standard NA A+ pistons, or turbo type ?
The turbo type will handle plenty, the NA standard ones I have no first hand experience of, but they're not a bad piston, so I'd say you'd probably be ok at 7-8psi maybe a little more ?
You need to consider the compression ratio of the engine you're hoping to use, this will go a long way toward dictating how much boost you can safely use.
With a decent head you'll make more power on the same boost or the same power with less boost when compared with a stock head, how much power are you hoping for ?

Phil.

WWW.TURBO-MINI.COM

They'll be standard pistons. I've punched the engine code into guessworks and its an A+ that was 9.4:1 compression from factory.

But I know the head has been skimmed at least once so it might be closer to 10.

My reason for asking is I was quoted £800 for a worked head and the supplier suggested the head would be capable of ~85bhp and #90 lbsft of torque. I thought I could probably build a turbo setup for less than that.

Anything over 100 would be great.

With 9.4:1 compression it won't take much boost at all. You need to budget in lowering compression with either different pistons or a worked head. I doubt it will be any cheaper than the NA route.

I disagree. The MT turbo ran up to 7psi on 9.4:1 and made 94hp if you believe the spec

With an intercooler I,m sure a little more boost and fuel and over 100hp would be on.

I ran 10 psi on Midget pistons at about 9:1 and got 110hp without an IC but I was never convinced it would last very long,pistons being the concern.

Methanol injection is going to be your friend.

I'm the same vein, once you spend the money on everything to make it run at high compression you may as well have gone the NA route. I don't think there's a cheap way.

Max 9psi boost, decent intercooler and a rolling road set up to ensure it's getting enough fuel should see north of 100hp. After that yes I would start opening things up.

So theoretically 9 psi on a completely standard engine is possible?

9 psi on standard metro turbo pistons would be no problem, but from what you have said it appears you are talking about a standard 60bhp NA 1275. The pistons might not be up to it.

We did run more with a rich needle and decent intercooler, but as per the other comments I wouldn't advise it! To be honest if it's a bog standard non turbo 1275 they are all getting old I would just rebuild it, or boost it and accept it may not last. The turbo pistons are a stronger design so compression is only part of it.

Edited by minimole23 on 22nd Jun, 2017.

There is no cheap way to boost an engine, you can literally throw a turbo on it and the carb etc, but it will end up goosing your engine and you will have lost everything.
Take the time, save up the money and do whichever route you plan properly.

Edited by Carlzilla on 22nd Jun, 2017.