how much psi can the stock motor hold?

[AVodka14]

I love teaching moments. Educate me how smaller vs bigger turbos can put different volumes of air at the same PSI. Is it simple physics of ratios....i.e. volume per unit of pressure?

As far as reliability is concerned I understand having it tuned well is your best bet. As stated above.

[billwot]

Originally Posted by AVodka14

I love teaching moments. Educate me how smaller vs bigger turbos can put different volumes of air at the same PSI. Is it simple physics of ratios....i.e. volume per unit of pressure?

As far as reliability is concerned I understand having it tuned well is your best bet. As stated above.

You can't. You can't "flow more air at the same pressure".

The only way to get more air into a fixed volume (the space above the piston) is to increase its density (pack more air into a smaller unit). And air density is directly related to pressure, and inversely related to temperature. So to increase air flow into the engine, you either increase the pressure, or decrease the temp.

That's the whole basis of FI. The more you pressurize the intake air charge, the more fuel/air charge you can push into the cylinder.

To increase power, you need to increase the mass (weight) of air, not the volume.

[AVodka14]

Originally Posted by billwot

You can't. You can't "flow more air at the same pressure".

The only way to get more air into a fixed volume (the space above the piston) is to increase its density (pack more air into a smaller unit). And air density is inversely related to pressure, and inversely related to temperature. So to increase air flow into the engine, you either increase the pressure, or decrease the temp.

That's the whole basis of FI. The more you pressurize the intake air charge, the more fuel/air charge you can push into the cylinder.

To increase power, you need to increase the mass (weight) of air, not the volume.

That makes sense. Reminds of Chem II and Physics I in undergrad. Great explanation.

[Braces]

Noob question. I've had stock turbocharged cars in the past and iirc they were on low compression engines. Our engine is high compression. does it matter? High vs low compression?

[Reaper]

Direct and port injected. Smarter ecm. Better combustion chamber shape. But still has limits. Like 325whp on 93. As an example the fa20dit is turbo, around 300hp and comes with a warranty with only slightly lower compression.

Sent from my SAMSUNG-SGH-I747 using Tapatalk

[billwot]

Originally Posted by Braces

Noob question. I've had stock turbocharged cars in the past and iirc they were on low compression engines. Our engine is high compression. does it matter? High vs low compression?

Absolutely! FI increases the effective compression ratio. 1 bar boost (approx 14.5 psi) effectively doubles the compression ratio, so for our cars, 14.5 psi would give you an effective 25:1 compression ratio.

The biggest risk with FI is detonation, so the real question is how much boost can you run without getting detonation. The higer the CR, the greater the risk of detonation. That's why factory-built FI cars almost always use lower CRs than naturally aspirated cars.

Effective Compression = ((Boost PSI / 14.7) + 1) * Current Static Compression Ratio

And here's a calculator for effective CR:

http://www.gtsparkplugs.com/Effectiv...ssionCalc.html

[Celadrielas]

Originally Posted by MidnightRunner

I agree. Different strokes for different folks. Awesome na thread on here if you haven't seen it already:

http://www.ft86club.com/forums/showthread.php?p=1796150

Or if you wanted a more simple route to your goal, the innovate sc or speed by design turbo gets you there at really good prices. Just my two cents.

haven't seen it and will catch it when I get home. Thanks

[whatsinaname]

[regal]

How many thousand miles do you want the car to last 1k,10k,100k,200k, or 300k ?

[EAGLE5]

With a good tune, you'll replace your transmission, fuel system, drive shaft, clutch, and axles before you replace the engine. With a bad tune, boom!

[JAK_SPYRO]

The FA20 can comfortably and easily handle 9-10 PSI. You can safely go up to 12 PSI, but you should secure all valves that hold pressure like the PCV side and any other valve you see that doesn't have a clamp. Also upgrade the PCV it self to an STI one IF you are turbo charging it. If super charging, go with the Jackson Racing PCV. Also make sure that you upgrade to 5W-30 for any PSI above 9 instead of the 0W-20 because you will burn oil fast. Going above 11 PSI, make sure to upgrade the engine mounts and my favorite are the Perrin ones. Other than that I would add 2 oil catch cans on the PCV side and on the intake side if turboed above 9 PSI. For super chargers add 1 oil catch can on the PCV side. In general make sure to have a big enough intercooler and if needed upgrade the radiator to a Mishimoto one. I would personally remove the AC to lose 30 pounds of weight, not have a lack of power when the AC is on, and get more airflow to the radiator by removing the condenser. Also don't forget about your transmission, anything above 9 PSI will need a stage 2 clutch depending on how you drive and make sure to get a lightweight flywheel for better accelerating. Good luck to everyone and have fun with the awesome tuner FA20! Please be responsible and do not go above 13 PSI without upgrading the internals like the pistons, rods and mainly, the block. If you have any questions, do not hesitate to message me

[stevesnj]

Originally Posted by JAK_SPYRO

Going above 11 PSI, make sure to upgrade the engine mounts

Just curious why you say this?

[JAK_SPYRO]

Originally Posted by stevesnj

Just curious why you say this?

Just from personal ecperience, the FA20 engines all shift to the left and actually bend over a bit when put under pressure. If you pay close attention to every engine in all Dyno videos, the engine just leans to the left and jumps right back when letting go of the gas pedal. Obviously this is normal and since the stock mounts are plastic, they can be flexible at time, but to me that's not good, the engine shouldn't move that much especially when you're racing and need the engine to be still to make the most constant and efficient power

[Jaden]

It's a crap shoot. If you've been running at 340 whp for a while on e 85, you'll probably be alright to turn it up a little. 20psi may be too much I wouldn't go over 15 if I were you without building the motor.

As has been stated, there are people out there who have been running north of 500whp but there are people who have lunched motors at less than 300whp.

It seems there is a common theme of either defective rods or bad tunes or a combination there of.

The rods are what seems to fail most readily, so if you really want to run 20psi of boost, I would suggest at least getting some forged rods for it. but if you're going to rip into the engine anyways, you might as well do it right.

You have to think about taking the risk though because it's not like you're likely to just lunch some bearings requiring a rebuild if it does fail at 20 lbs of boost. Like I said the most likely failure are the rods which usually result in complete catastrophic failure requiring a replacement block.

It could be an expensive lesson.

Jaden