silvertop 20v to turbo

[toymaz]

thats ARIAS claims for their pistons , not mine!
wouldn't the compression height of the pistons being different 16v and 20v change the comp?

[Sam_Q]

yeah I know. Yes the compression height would change things. They should be the same and if they are smaller to lower the compression then thats a very poor practice

[adamaw11]

how would someone get about a 10:1 compression ratio with forged pistons with a blacktop head?

what does it take to get custom made pistons made up?

[Youngy]

Talk to special piston services in Vistoria.

Address: Factory 13 112 Hammond Rd, Dandenong, VIC, 3175

Phone number: (03) 97931110

They do custom work.

[Sam_Q]

how would someone get about a 10:1 compression ratio with forged pistons with a blacktop head?

what does it take to get custom made pistons made up?

probably the acl/mahle pistons and a 0.8mm head gasket, want me to calculate it

[adamaw11]

probably the acl/mahle pistons and a 0.8mm head gasket, want me to calculate it

just for interest sake at the moment, if you feel like calculating it go ahead.

I figure anything below 9.5:1 wouldn't be 'interesting' enough for a high-comp turbo 20v build.

[Sam_Q]

ok when I am back home I will work it out. I would think 9.5:1 would be decent but yeah 10:1 would be neat

[Sam_Q]

ok done, heres what I worked out using a 35cc assumed ST chamber, 38cc BT and a flush deck height:

1.2mm gasket-

ST 10:1
BT: 9.41

0.8mm gasket-

ST: 10.42:1
BT: 9.8:1

7AFE bottom end, 1.2mm gasket and with Mahle pistons:

BT: 10.32

[DX20VT]

I built a silvertop 20V Turbo motor a few years back with bits and pieces that I had aquired
to compare against my race spec engine I had in the car at the time.

I took a 100% stock standard ST 20V and put AE101 GZE pistons and rings,
new head studs and rod bolts, and slapped it all together with a new head gasket,
and fitted it in place of my race engine.
Put 20psi and a decent tune into it and it made as much power as my good low compression race motor.
I actually ended up running it for about 2 race seasons before selling it off and it is still running now.

It made about 200kw atw with a hybrid modified T28 turbo.

And as far a a budget build, there were no expensive bits in it other than having to buy the Toyota pistons and rings.
But that's just the base engine. There's also having to make the inlet and exhaust manifolds.

Same can be done with a BT, but you'd need to replace the rods with earlier version ones.

[Sam_Q]

well said. So what was the specs of your race motor then?

[DX20VT]

well said. So what was the specs of your race motor then?

The engine I had at that time was built for massive boost, about 30psi,
before the class I race in was limited to the 18/20 we are allowed now.

Was basically a ST 20V, with aftermarket cams and cam wheels, extensive headwork
with heavy valve springs and aftermarket ross pistons with 7.8:1 comp ratio,
and all the usual race stuff.

I still have that engine in the garage, doing a rebuild on it now,
But when I sold the engine referred to in the previous post I went to the 1800 7A hybrid.

[Sam_Q]

oh ok, I am guessing that compression was too low for the boost limit right. Either way for any dyno 200kw is impressive and well done to you

[DX20VT]

oh ok, I am guessing that compression was too low for the boost limit right. Either way for any dyno 200kw is impressive and well done to you

Yes and no. It still made the same power around 200kw at 20psi, I presume the other mod's made up the difference,
but it was very peaky and had a very narrow power band as with the lower compression,
and different cams etc, it didn't come on boost till over 1000rpm later than the high comp version.

[sprinter86]

I have the ROSS made, ACL brand silvertop pistons in my turbo engine(i think sam is referring to my engine) and yes, the compression still seems quite high, the 10 to 1 calculation sounds right.

For anyone thinking of buying these pistons, be warned, the arrow stamped on them to ensure you install them the correct way into the engine are BACKWARDS. a quick look at the valve reliefs will see you installing them correctly. (have a look at the photo on the acl website, you will see the stamp is on the wrong side of the piston.)

i have yet to get to a dyno to properly tune my engine, but i will post my results when i do.

[Sam_Q]

Oh yeah I forgot about that arrow thing, again how could such a professional company get something so simple wrong. Did the apprentices make these or something?

Would very much like to see that dyno result