998 pistons
Turbo Mini Forums

Ive got some 998 standard dished pistons from an automatic.

When kind of bhp can standard 998 pistons take?

Gather parts for a 998 turbo future project.

Thanks

David

The limit isn't really the bhp. Rather the rpm or heat.

What pistons are they exactly? 20773?

if they are, then I've run them up to 18psi 6500rpm and 140bhp. And they lasted ok.

However, when I changed to a turbo that turned out to be less efficient at 15psi the pistond quickly took a dislike to is and fell to bits.

What are you planning?

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

im currently building a 1380 on carbs but the build has taken longer than expected due to the time it takes to gather all the parts. This build has cost me alot.

Im hoping to use the parts in my garage along with a nice new cam, head and turbo to make a nice 998 turbo hopefully with around 100 bhp if not more. Once the 1380 is finished but i want to start gather parts now to save time later.

I want the build to be cheaper than my 1380 and like the idea of turbo as they just seem more interesting than a normal engine.

So far i have a complete 998 unit some standard dished pistons and a choice of head either a 1275 stage 3 <get block pocketed> or a 998 cooper im yet to work out the compression this will give me but i gather it will be quite low good for turbo?!

Im very impressed with your 998 turbo wil_h its very impressive.

any advice on cam choice and compression ratio?

Thanks

ive also got some +20 thou rings for free :)

My experience of cams is limited, but all my 998 turbos now run the MG Metro cam (or Kent 500).

CR depends on what you want. for 100 bhp, as long as you run an IC I'd keep it at 9:1. Drop it down to 8.5 an you'll be able to run more boost but compromise off boost performance.

My hillclimber runs 8.5 the road 998 runs 9.3

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

the 998 cooper head (12g295) should drop the cr to about 8.5 ish straight away, and would avoid pocketing the block etc

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

Ive got a kent 270 fast road cam lying around would this be any good on a turbo 998?

Thanks

The 270 is probably a bit to severe, it'll really kill the off boost power

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

if i use the 998 with a standard turbo of a metro turbo the cooper head and a kent 500 cam what kind of power would i be looking at?

I managed 140 bananas at 18psi with a similar spec.

The T3 is a dog on a 998 though.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

what turbo should i go for?
Thanks for all your help wil

There is a reasonable choice. I currently run a T2 from an R5 turbo see here http://www.turbo-mini.com/62147.html

This is a great turbo for low boost threshold and moderate psi (upto 12), people run these upto 15psi, but they haven't seen the compressor map!

We're building one with a GT15 atm, but no results on this so far. The GT17 will give you all the power you want, but does compromise the low end power compared to the T2.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

from discussions and reading foreced induction performance tuning ideally we want a something smallish one from a modern turbo diesel with variable vanes over a wastegate, Ideal for small capacity engines they come on new espace's audis and VW's..

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

i thought they used normal actuators connected to a lever arm which controls all the vanes together!?

most of the time on disels they use vacum to operate the vanes on VNT's.

on the dodge shadow they had a presure and vacum side on the actuator this is the setup i am initially going to try,

http://www.thedodgegarage.com/turbo_vnt.html

diesels do not regulate the air drawn into the chambers with a throttle butterfly so there would be no vacum? unless there is artificial vacum created for the brake servo..?"!
cant you get electronic devices to replace the plenum fed pressure feeding the actuator allowing much better control..