Testing The Waters

[w00t692]

Just so you know, the average amount of boost run on a honda k series is 12-14 psi on stock internal and this will last literally years at this power level.

That's a static compression of 19.98:1 @ 12 psi and 21.48:1 @ 14 psi.

There are even quite a few cars running slightly more than this successfully for long period of time (16-18 psi)

Truly, it just sounds like the stock rods and pistons are a weak point in this engine, as the static compression ratios you're talking about really aren't that excessive.

and honestly those compression ratios you speak of are the effective compression ratio, you can't have a static compression ratio with boost, as the boost isn't there

[Jason@DSG]

Originally Posted by wparsons

Except that if the engine makes 300whp on 8psi with 12.5:1 compression it's going to make a substantial amount less on 8psi with 9.0:1 compression.

More boost means you're heating up the incoming air more, higher IAT's can also cause detonation.

Ultimately you have to tune for the setup, but there's no reason you can't run higher c/r's with boost.

You can't compare how a built engine takes power compared to one with stock internals, I would bet that peak power output on a built engine with 12.5:1 pistons would be very similar to one with 10.0:1 pistons, but with less lag and a broader power band.

As I mentioned above, there are very few turbo applications with high CR's. It's too risky. That's why these kinds of parts exist. You can run small boost on a non factory FI engine, but you can make it what it should have been.

Also, it will make very close to the same power, and much safer. maybe 20-25whp difference, but it will also allow much more boost to exceed even the original 300whp and have a much safer CR under full load

[STV3]

Originally Posted by Jason@DSG

Most factory 4-cyl turbo engines are actually 8.0-9.5:1 (4B11T, EJ207, EA888, etc.)

Yep my SRT-4 is 8.1:1 from factory and can run about 22-23 psi safely on pump gas. Im running around 26 right now with a little bit of meth

[Jason@DSG]

Originally Posted by w00t692

Just so you know, the average amount of boost run on a honda k series is 12-14 psi on stock internal and this will last literally years at this power level.

That's a static compression of 19.98:1 @ 12 psi and 21.48:1 @ 14 psi.

There are even quite a few cars running slightly more than this successfully for long period of time (16-18 psi)

Truly, it just sounds like the stock rods and pistons are a weak point in this engine, as the static compression ratios you're talking about really aren't that excessive.

and honestly those compression ratios you speak of are the effective compression ratio, you can't have a static compression ratio with boost, as the boost isn't there

Your static compression affects full boost compression which was my point:

http://www.goodvibesracing.com/Compression_Ratio.htm

And a Honda K series isn't an FA20 so you can't compare them. They also start burning oil like crazy those K series and don't last under racing applications. Any race series K has forged internals and a built valvetrain.

Also, what I was pointing out is simply (as I mentioned, this was all just numbers and theoretical data): lower the compression for a boosted application keeps things safe as well as having forged internals for racing applications

This car has a lot of untapped power and running 12.5 compression is not the way to go for any big power. Even bigger muscle cars run in the 9 CR.

[Jason@DSG]

Originally Posted by STV3

Yep my SRT-4 is 8.1:1 from factory and can run about 22-23 psi safely on pump gas. Im running around 26 right now with a little bit of meth

Shhh don't say that here, everyone wants to run 19.5:1 compression @ 6-8 psi

[STV3]

Originally Posted by Jason@DSG

Shhh don't say that here, everyone wants to run 19.5:1 compression @ 6-8 psi

[wparsons]

If you look at an SRT4 with a stock turbo, they make about 230whp on ~14 psi, from a 2.4L engine. How much boost does it take to make 230whp on an FA20, WAY less than 14psi. Who cares if the engine can take twice the boost if it needs twice the boost to make the same power? I'm guessing about 3-4psi would get you above 230whp easily, with way less heat than running 14psi.

Boost amount alone isn't the full story.

How does the SRT4 respond to throttle off boost? Hint, it's not great.

@STV3 - how much power are you making on 22psi?

[Jason@DSG]

Originally Posted by wparsons

If you look at an SRT4 with a stock turbo, they make about 230whp on ~14 psi, from a 2.4L engine. How much boost does it take to make 230whp on an FA20, WAY less than 14psi. Who cares if the engine can take twice the boost if it needs twice the boost to make the same power? I'm guessing about 3-4psi would get you above 230whp easily, with way less heat than running 14psi.

Boost amount alone isn't the full story.

How does the SRT4 respond to throttle off boost? Hint, it's not great.

@STV3 - how much power are you making on 22psi?

You can't compare the two. It's not the same turbo, one is a factory turbocharged engine and the other isn't.

IE. while he's make 230whp at 14psi, that's downtuned from the factory. He's probably making about 350whp now at 22-23psi and the engine is easily capable of that (MOPAR STAGE III).

Whereas the FA20, yes you can make 280-300whp fully tuned, full bolt ons on 8psi. However, that's the most you can do before it blows up. Try running 14psi on your stock FA20 and let me know what happens. Bye bye engine

So that brings me to my point all along.....allowing the FA20 to run 14-20psi with proper LOWER compression and forged internals would be pretty damn potent wouldn't it Lot's of untapped power and potential here. I'm betting 9.0:1 on this car at 18-20 psi would make in the 450whp range with a proper turbo/intercooler setup.

[STV3]

Originally Posted by wparsons

If you look at an SRT4 with a stock turbo, they make about 230whp on ~14 psi, from a 2.4L engine. How much boost does it take to make 230whp on an FA20, WAY less than 14psi. Who cares if the engine can take twice the boost if it needs twice the boost to make the same power? I'm guessing about 3-4psi would get you above 230whp easily, with way less heat than running 14psi.

Boost amount alone isn't the full story.

How does the SRT4 respond to throttle off boost? Hint, it's not great.

@STV3 - how much power are you making on 22psi?

I dont know because my car was tuned on 26psi and made 417whp 415tq. When I am not in boost it drives no different then my FRS. If I were to swap to a larger aftermarket cams then I may have some low end torque issues but that is not the case.

[wparsons]

My point was that it's a larger displacement engine making less power on way more boost.

The key to holding together with more power is stronger internals, not a lower c/r. Give an FA20 forged internals with 12.5:1 c/r and it'll hold a lot more power than the stock internals too. Sure tuning isn't as foolproof, but that's not a good reason to not do it.

I'll take harder tuning to get way better throttle response off boost as well as less lag and cooler IAT's every day of the week.

[STV3]

Also my block, internals and head are bone stock

[wparsons]

Originally Posted by STV3

Also my block, internals and head are bone stock

That's because Dodge way over built the engine stock, they're known to be very strong from the factory.

It doesn't hold 400whp + because of the low c/r, it holds it because it has very beefy internals stock.

[w00t692]

Originally Posted by Jason@DSG

Your static compression affects full boost compression which was my point:

http://www.goodvibesracing.com/Compression_Ratio.htm

And a Honda K series isn't an FA20 so you can't compare them. They also start burning oil like crazy those K series and don't last under racing applications. Any race series K has forged internals and a built valvetrain.

Also, what I was pointing out is simply (as I mentioned, this was all just numbers and theoretical data): lower the compression for a boosted application keeps things safe as well as having forged internals for racing applications

This car has a lot of untapped power and running 12.5 compression is not the way to go for any big power. Even bigger muscle cars run in the 9 CR.

There's tons of oem race series using stock stuff, you speak like the stock internals are weak, yet people run 400+ whp without issue.

Cmon now, don't sell those engines short.

High compression + boost is amazing

I'd make:

9.5:1 pistons
10:1 pistons
and 11.5:1 pistons

Since all the demand seems to be mostly for boost anyways.

[CajunFRS]

2.0t Genesis has crap internals and its FI from factory. Plenty of guys who tune that car end up with issues. Stock internals vary widely is all I'm getting at. The SRT4 block/head is not the norm.