good compression for turbo

[blue]

i have a d16z6 and was wondering what a good compression for a turbo application would be.

[rmcdaniels]

Here's the math to figure it out, but it depends on what you want to use the car for.

http://www.highaltitudeimports.com/t19643-.html

[Mario]

Here's the math to figure it out, but it depends on what you want to use the car for.

http://www.highaltitudeimports.com/t19643-.html

Just for shits and giggles, I tried it with my planned setup.

((7/14.7)+1)x10.5 == 15.5

You said effective compression to be reliable and solid is 18-20.... any insight on my future setup here? 7psi on a b16a.

[rmcdaniels]

Just for shits and giggles, I tried it with my planned setup.

((7/14.7)+1)x10.5 == 15.5

You said effective compression to be reliable and solid is 18-20.... any insight on my future setup here? 7psi on a b16a.
18-20 effective on a built engine with forged internals, I'd keep it under 18 effective on a stock engine. I've heard of people running 10 PSI on a stock B16, but I knocked the ring lands off mine with 10 PSI, although my engine management was crap at the time. So I can't tell you what to run, because I won't pay for it if it blows up, but I'd run 8-9 PSI on a daily driven JDM B16 with very good management and tuning.

[Mario]

Fair enough. My initial setup will be an AFC, 450's, and Walbro pump with transition to Uberdata soon after.

[blue]

Here's the math to figure it out, but it depends on what you want to use the car for.

http://www.highaltitudeimports.com/t19643-.html
how does that make sence...ur saying if i were to run 20psi i would need 19.8:1 compression pistons....how does that work......never seen pistons for 19.8:1.............

[ryanman]

Ask myshtern, he knows all about comp ratios and what's best.

[rmcdaniels]

how does that make sence...ur saying if i were to run 20psi i would need 19.8:1 compression pistons....how does that work......never seen pistons for 19.8:1.............You have to use the formula. In case I wasn't clear, "motor compression" in the formula refers to the static compression ratio of your pistons. If you want to run 20 PSI, then you'd be looking at about 6.77:1 pistons to keep it relatively safe. Here's how the math wortks:

((boost psi / 14.7) + 1) x static (piston) compression = effective compression

So if we want to keep the effective compression down around 16:1 to keep your stock rods intact, and you want to run 20 PSI of boost, we just plug the numbers in:

((20 / 14.7) + 1) x static compression = 16

Solving for static compression gives us 6.77, but 6.77:1 pistons would probably be too low for a daily driver, so let's upgrade your pistons and rods to forged units so we can run 18:1 static compression. The new formula is:

((20 / 14.7) + 1) x static compression = 18

That gives us 7.6:1 pistons, which is still a bit low, so let's say we will only go as low as 8.5:1 on the pistons and solve for boost. Here's the formula:

((boost / 14.7) + 1) x 8.5= 18


Solving for boost gives us about 16.5 PSI of boost with 8.5:1 pistons, which isn't bad. If you can do that math, then I've got another formula that will tell how much power you will make at that boost level, but it's a little harder.

[Mario]

If you can do that math, then I've got another formula that will tell how much power you will make at that boost level, but it's a little harder.

I would like to see this equation. :)

[blue]

ok give me the next formula and also "static compression" = PSI???????

[Weston-work]

I would like to see this equation. :)

:werd:

[JL LGT]

This thread RULEZ! Keep it coming RMcDaniels! That first link you provided has been printed out!

[rmcdaniels]

ok give me the next formula and also "static compression" = PSI???????
static compression = the compression ratio of the pistons

[rmcdaniels]

I would like to see this equation. :)
I'll have to find it again. I had a link to an article on www.turbosaturns.net (http://www.turbosaturns.net) that explained it, basically calculating pounds/minute of air and AFR to figure out power, making some VE assumptions and getting it pretty close, but the turbosaturns site appears to be down and Google doesn't have a cache of that article.

[rmcdaniels]

Looks like they're back up. Here's the article:

http://www.turbosaturns.net/articles/compressor%20maps_2.htm

[Zach]

dude, awesome site. thanks for finding it again