Just sorted some Mahl low compression racing pistons, just need to upgrade my rods now then my car can be tweaked.......again:D

But what will these low compression pistons do for my engine, how will they be better? What will be changed when tweaked?

Standard comp: 9.5:1

S3 comp: 8.9:1

Mahl comp: 8.5:1

Any info will be gratefully received!!

Cheers:thumbup:

I lower compression means you can run higher boost as there will be less cylinder pressure.

But its a trade off as lower compression means less power.

I lower compression means you can run higher boost as there will be less cylinder pressure.

But its a trade off as lower compression means less power.

Wouldn't that be compensated by increasing the boost pressure though? Jabba said with up-rated internals I could add 50ish ibs/ft torque and 25-30bhp, as well as making the engine much safer, especially when driven hard.

yes the higher boost will bring bacl more power than you lose. but will work the turbo / i/c / injectors harder. but the block less.

What is the best answer then? Do I stick with standard pistons and just uprate the rods?

I thought that the 'AUQ' engines weak link was its internals (pistons & rods), especially when compared with the 'BAM' engine.....

If high power is your goal, then go for the Mahls. Down side of lower compression tends to be lower MPG (ISTR somewhere in the region of 7-10%) and a less useful engine off-boost.

8.5:1 is not that low in absolute terms, compared to the Cossie lot and certain modified Imprezas.

J.

Just sorted some Mahl low compression racing pistons, just need to upgrade my rods now then my car can be tweaked.......again:D

But what will these low compression pistons do for my engine, how will they be better? What will be changed when tweaked?

Standard comp: 9.5:1

S3 comp: 8.9:1

Mahl comp: 8.5:1

Any info will be gratefully received!!

Cheers:thumbup:

Get pauter rifle drilled rods to compliment your pistons. They are the only rod I know that provide pressurised oil feed to the small end bearing, like the standard rods. Many rod suppliers rely on oil splash to lubricate the small end bearing, but I found this to be insufficient. I got small end bearing knock off load with my first set of rods. Swapped to pauter rifle drilled and it was quiet as a mouse. Do it right first time and save yourself some money.