Gti6 Head On S16 Pistons And Connecting Rods

[Darko_BG 0 1 Cars]

Hi guys,

i have a question for you i would like to try something but i don't wont to destroy engine.

My engine block is RFS,inside are pistons and connecting rods from s16,and head is from GTI6 i was reading about 1.9TD crankshaft in s16 engine but i supose it is with s16 head,what would be if i put TD crankshaft in my engine with GTI6 head?

Edited May 8, 2016 by Darko_BG

[petert 586]

If crank/rods/pistons are S16, then the piston crown should be 1mm below the deck at TDC. Using an 88mm crank will bring the piston flush with the deck at TDC. Whilst this is good in terms of increased capacity and CR, you will need to check your valve-piston clearance and pocket the pistons accordingly. It doesn't matter whether it's GTi6 or Mi16 head.

[Darko_BG 0 1 Cars]

My plan is to remove gearbox,oil sump,and to drop the crankshaft.Can i check valve-piston clearance from that position or i need to take head off?

[dcc 855]

Take engine out and do it properly, else you'll be in a world of s*it

[welshpug 1,657]

you measure valve clearance by checking how far a valve drops with the piston at or just past TDC, remove the main spring and use a light weight spring and a DTI gauge on the top of the stem.

 

you'll need to remove some material from the pistons to reduce the compression, or make the cutouts larger and run wilder cams.

[Darko_BG 0 1 Cars]

I need to remowe material because of GTI6 head or i would need to that with S16 head too?

[welshpug 1,657]

both, but more so with gri6 due to smaller chamber

[petert 586]

S16 pistons have big cut outs, but until you drop a valve onto the piston you won't know what the total clearance is. I know my Stage I cam fits with that spec and it has 0.065" lift at TDC. My Stage II doesn't fit and it has 0.105" lift at TDC. It's going to have around 11.25:1 CR and will thus need more than standard cams. You'll need cams with around 0.080" to 0.120" lift at TDC, else it will have too much dymanic compression. Build it properly and will run fine on 98 octane fuel.

[Stu 18]

This is more or less the exact spec of engine i'd planned on building next, got a good '6 head with one of your stg 1 cams Peter, and a set of S16 pistons and rods with an Mi crank.

 

I'd generally thought the cut outs in the pistons were ok with this lift? i know the compression is quite high mind!

[petert 586]

When you hear the engine running with over 11:1 and those cams you'll say to yourself, "I should have gone bigger". The cranking pressure does get high and can limit ignition timing.

[wicked 103 3 Cars]

With bigger cams (longer duration), your dynamic compression will drop compared to mild/stock cams. And that is the reason why you want higher static compression; to compensate for the dynamic compression drop. It's not a goal on its own to have high static compression. It goes hand in hand...

 

Your dynamic compression should remain in the same ball park as the stock engine.

Increasing dynamic compression will limit the ignition timing. Dropping dynamic compression will give a lame engine.

[Darko_BG 0 1 Cars]

If you get bigger compression i think for atmo engines from 11 to 11.5,more Nm,if compression is 12:1 - 13:1 that is bad for performance and engine i think..