edwardsuen

I have Supertech P4-MA790-N1 Forged 4032 Aluminum Pistons with C4122-040 Cometic Head gasket on a 1.6 B6 Engine, with AE111 4 AGE black top ITB, Eagle Rod, 4 to 1 Header, wonder how to calculate the max high lift cam I may use in order not to hit the High Compression Piston?
From nolimitmotor sports, I notice that I have 1 cc additional space in between valve and piston, so, how to calculate 1 cc to lift angle? in order to stay away from piston even if cam belts broken....
Since I do not have a dyno, anyone may guess actually how much more I am gaining? 20HP if install 254 Intake + 260Exhaust?

And anyone knows how much more compression ratio do I get using .40 head gasket instead of .60?

Thanks

NiklasFalk

iTrader: (1)

Measure (and use no HG to get the rod stretch margin)!

And it's not always the max lift at TDC that is critical, it can be tight when the valve is entering the relief.

Using the HG to gain/loose compression is not the way to do it. Get the proper pistons and/or deck the block. No reason to use anything else than a stock MLS HG.
There are many tutorials available how to calculate compression ratios.

Savington

iTrader: (31)

You don't calculate anything unless you've modeled the entire engine in CAD software. If you want to know how much lift YOUR engine can handle, you spend a lot of time disassembling and assembling it with clay on the piston heads to produce a dataset of clearance vs. valve lift vs. piston position, and then build cam profiles based on that and on the limits of your valve springs.

IOW, you ask your motor builder to do it for you.

edwardsuen

Thank you!

I will take the deck block option next time, as I brought the .40 gasket anyways, will put it on, and try to borrow the High Lift Cam and test out the limits with clay options.

Since not much HC piston for a 1.6 to choose from, there are only three choice:
1.) Supertech 10:1 79mm (1638cc)
2.) TODA 11:1 81mm (1722cc)
3.) Wiseco tailor made

For above three, only TODA can be sure to handle 264I + 272E, as they sell these as a kit, any higher is unknown..

I love the clay option, I will try to borrow HL Cam to test out the SuperTech +.40 HG limits.. Glad that Cometic HG is good for many use, so I may do as much disassembling and assembling as I wish..

Yes, I am doing this myself
One thing I do not understand is it will be more critical when valve is entering the relief.. wouldn't the piston is travelling away from valve when valve is entering relief...

Thank you again...

Savington

iTrader: (31)

Don't know who told you you can re-use a Cometic gasket, but that is false. Once you torque and untorque, you should change the gasket. You can use an old head gasket, or none at all to simulate the small amount of rod stretch.

0.040" is also too large of a head gasket, unless your block has been appropriately decked. Again, more questions for your motor builder to answer.

edwardsuen

I got the reuseable thread here, I will use a old head gasket to do the measurement then..
For .040 is too large? I am confused, thanks for reminding me, I kept thinking that the measurement is in mm, this is why I am worrying about hitting the valve, guess I do not need to worry since it is higher the stock, even I got raise piston will not hurt then..

Stock = 1mm
Supertech Recommended = .060 (acutally 1.53mm) NOT .06mm
My shop said usually ppl uses = .040 (actually 1.016mm) NOT .04mm

One more questions that I could not find via forums, I understand using Wiseco Piston will need to bend the oil nozzle away from spraying the bottom of piston due to the oil passage design in Wiesco, but for SuperTech ones, do I need to also bend the oil nozzle away, or I can keep it? I saw oil passage in SuperTech also...






I saw ToDA website said 81mm bore match with .8mm HG, so slightly thinner (smaller) then stock HG, therefore, should be slightly more Compression Ratio.. these are the information I am get and compares the different before I brought the items..