Quote:
Quite a careless splurt - there is more to it but pat yourself on the back if you think youve nailed it.

The vitara pistons I have measured in my possession tonight g16b and g16a have 28.5mm and 27.75mm comp height. The 27.5mm one was milled for my brothers 1.6 Sierra which threw a leg out after 210,000klms from severe overheating and trying to drive it home. After 1 year he got lazy by replacing expired coolant with water for another 5 years and kept overheating and refilling for months until it had enough.

Rings, comp height and pin size are:
G16b
1.2, 1.5 and 2.8mm , 28.5mm , 19mm
Late A12
2mm, 2mm and 4mm , 32.5mm , 19mm

The Vitara OEM slugs on inspection seem weaker than the A12 due to ring sizes and crown design. The vits have very little support around the crown with 4 valve indents coming close to the top ring while the single E15 piston I have has 1.5mm, 1.5mm and 4 mm and nice decomp dish design. Anyone wanting to test the A12 vs g16b slugs is welcome to take them for postage price only for more accurate tests or analysis as they are junk remnants to me.

Hi Dave,
That A14 sounds like it would have been a bit of fun. How much boost were you running with the ign at 28deg?
Im using a standard type head gasket. Its a Durapro brand and $18 each when I bought three. Im using the ARP head stud kit that ive retensioned once after a working the engine for a while. Ive not had a gasket failure yet but doesnt mean its not just around the corner. It runs at a max of 80c(thermostat) on the track and i use a 16psi cap. The radiator is a VS commodore V8 core that ive made into a double pass unit and has no problem keeping it cool.

I was runing the engine fairly hard on the dyno yesterday. It picked up another 15Ftlb at 4,800 to 5200rpm. But started poping at the top end. I`ll check the valve clearances and springs today. Im not running enough seat pressure on the springs and im guessing this is starting to show itself now with the extra boost pushing on the back of the valve.

Hi Simon,
From memory 8 lb on the street and 12 on the track.Never wound it up too much and once I sorted a few issues out ( such as feeding it unfiltered oil from the oil pump and destroying several turbo cores ?!? ) it was very reliable. Used to use it as my daily driver, drive out to the race track and home again.
But as I said primitive compared to what you are up to. The figures that you are achieving just blow me away and to be honest if I didnt have the SSS that really is too nice to molester I would be seriously looking at replicating something similar to what you are doing.
By the way what gearbox/ rear end are you running?
Cheers
Dave

hats off to you sikyne!!!

unbeliavable power from a12 turbo.Your development thread could very well lead to a rise of turbo a-series rather than sr/ca/fj swaps into 1200s.This are power figures of 1.8liter plus capacity engines but with the light weight of a-series engines.

keep it up mate

from sandown, sikyne's beast




full size

If you're still going to be running stock pistons, have you considered thermal barrier coatings on the crowns as a bit of cheap insurance? I had the E5 pistons in my a15 done, as well as dry film lubrication on the skirts too.
The E15 pistons D mentioned earlier, are a very strong looking bit of kit. No oil drain holes behind the oil control rings, just slots above the pins. Amd VERY thick crowns. Probably no use to you if you're stuck with 1200cc for class regs.
Another place where you might sqeeze a bit more power, is I'm told that with a little clearancing to the roof of the lifter area that the SD22(Or was it sd23?) lifters will fit an A series. (B110SSS runs a set in his engine) As these have a larger diameter face, you could probably get a cam ground with the same specs as you have now, but with a faster opening ramp. Get more charge in sooner, and perhaps even more charge into the cylinder, for the same boost figure.

Thanks for the input guys,


I`m using a 260Z 5 speed, I grafted it to the front of a 56a bellhousing,. The diff is a H165. The diff will need an upgrade soon. I hadn`t thought about the thermal coating on the pistons, I like the idea. How much does it cost and where do you get it done?
Thanks for puting up a pic Ange. Love the B&W!

Just put another engine together. 1mm larger on the inlet valve and 1.5mm larger on the exhaust and some porting. Ive also fitted some better springs.

I`ll have it running in a few days, I`ll keep you posted.

I hope its all good cos im racing at Sandown next weekend!

Man that looks tuff that pic!

I really don't believe in coatings or treatments in a high performance engine. Do you really think it's going to be fully intact after 20000k's ? and you are building an engine around the component being in that state indefinitely. I haven't had any conclusive proof that these coatings work to either increase horsepower / reduce friction. personally I'd rather spend the extra money or more headwork / machining where I can see the gains readily. or get the pistons / rods whatever made from the better material to start with.

Most new engines have coated internals & they seem to last well
Nissan QR25de has heaps of side loading with 1.48 rod stroke ratio
& coated slugs definitely do their bit. Alot of top racing classes
use them and at worst if they only last 20,000kms in a race engine
its definitely worth the investment to keep temps & friction down.