ryansmoneypit

iTrader: (6)

You can run vacuum only.

See you in 2020.

Sparetire

Best thread ever.

18psi

iTrader: (76)

his next post like that will get permanent hibernation

Goingnowherefast

iTrader: (1)

+1

Wingman703

great thread, would read again, 21/10.

Itty

You mean, will read again, 2110.

EErockMiata

in



acquired.

MartinezA92

iTrader: (4)

toasting an epic bread

Zachary Kidd

Ah yes. It is now 2019 and my first post and it must be here. Just absorbing info. See ya in 2020!

venetox

You mad bastard

Maka

2020 (first post) reporting in

From this thread I gather that around 12-15 psi is the max for stock internals. Good to know.

der_vierte

That totally depends on turbo size...

sixshooter

iTrader: (12)

There's a huge difference in cylinder pressure between 15 psi on a 2554 and 15 psi on a 3076.

Peak cylinder pressure timing is more important than you might realize, too.

It's complicated.

Godless Commie

iTrader: (2)

Best way to boost a stock engine is ducting the eyeball vents to the intake manifold.
You get instant electric boost.
You need to duct all 4 eyeball vents, otherwise you WILL get a boost leak.
​​​​​​​
Just turn the blower **** up all the way to 4 if you want to pass that Ferrari on a mountain road.

matrussell122

iTrader: (1)

What six means to say is all the boost a 3076 will put down in a YouTube video

Full_Tilt_Boogie

iTrader: (1)

So after 13 years we finally have concluded definitively that a stock engine can safely take several boosts.

mixer5

I know this is a old thread but, I'm wondering what your static compression is, I've got a 2001 LS that is 10:1 and adding 10psi will give me 15:1 total, any thoughts?

borka

iTrader: (1)

10:1+10=15?

Need more brain power to compute this one.

venetox

This isn't how compression works in an engine.

It's about the volume of the engine at BDC and volume of the engine at TDC. Pressure is not in the equation of compression ratio.
Only volume.

Of course pressure effects how much mass of air there will be at a given volume and temperature, however again the compression ratio is unaffected, it simply compresses more or less mass of air, but still at the same ratio.

So if you have 1 litre engine, it will compress that 1 litre volume down to 0.1 litre of volume.
This comes with an increase in pressure due to the compression.

This doesn't care about the base pressure when the piston is at bottom dead center.

I.e.

You have 1 Litre at atmosphere (14.7 PSI).

You compress it and now you have the same mass of air compressed into a 0.1 Litre volume, this will increase pressure.

If you are turbo you might have 1 Litre at atmosphere + 5PSI so you have 1 Litre at 19.7 PSI.

You compress it and now have the original mass of air (1 Litre at 19.7 PSI at whatever temp your intake air temp is) compressed to the volume of 0.1L, this will cause an increase in pressure.

The compression ratio of the engine is still the same. It is still 10:1, it is just compressing a larger mass of air into the same volume.

Also note, that this is assuming perfect cylinder filling, i.e. the cylinder is completely fill of air at the mentioned pressure, however even when it isn't this doesn't effect the math, just the individual values of mass air being compressed.

sixshooter

iTrader: (12)

Thank you for the thorough explanation, venetox. I was just going to post the "that's not how any of this works" meme, but you did a better service to your fellow man.