how much psi can the stock motor hold?
 

does anyone know how much psi the stock motor can handle? im at 340whp at 11psi on e85 and im wanting to boost 20psi but im not sure if its a good idea or not

When you find the limit, let us know.

I've seen a lot of engine failures around 20k miles with boost, I wouldn't suggest putting much if any at all. There's a thread with a list of them.

All of which were reported with either bad tunes, improper supporting mods or just waaaay to high of boost. On pump gas 10-11psi seems to be the "safe" limit (with) a good tune. E85 14-16psi (with) a good tune and of course supporting mods in place day one.

Folks who have a good tune stay within respectable levels seem to be having zero issues. WHP wise under 300 particularity seems to work just fine with stock internals

You're out of your mind if you think this motor can hold 20 psi without support. I am starting to question this motor's reliability based on people's experiences on here. I have read the engine is very stout yet no objective data on this after seeing people with issues without boost. This motor was not intended to be boosted in my opinion. But if you do it right you can bump it up. Forged rods, pistons, HD clutch, etc.

There are plenty of people on here with variable experiences that can provide better input than me.

about 40psi

Interesting question! I know very little about this, but I think I can safely say, it depends on how long you want your motor to last.

Fullblown made 600whp on stock motor. Im at 380wtq and 450 whp at 9,000miles. Theres a guy near atlanta at 579whp and a guy in alphareta with 529whp. I know of them through facebook groups i think its dipstik sportec and sportsguy83 but im probably confusing real people with ft86 usernames. Lexusb was over 500whp as well and i think he was at 24,000 last time he posted. Oh and this motor was built specifically to be boosted, hence the fa20dit only having slightly lower compression and around 300hp. So if the factory build one at 300 im sure 350 isnt pushing it too much on pump gas with a little bit more compression but with a better turbo and tune. Im not scared of 400whp on e85 at all.

PSI is not as good a measure. CFM is what you're looking for.

I'm not boosted, but I know we have a few turbo / Supercharged running around my local meetup chapter. We have most pushing 320-350whp, I believe (uncertain of tq) but I know we have at least one at 400whp running E85.

He's run into some other issues though along the way. like the tail wants to step out under full throttle in a straight line. That and traction control just gives up. almost like it says "Too much power, fuck off -- I quit"

I'm personally going to be going N/A and aiming for around 230-250 and hoping for tq around 190-230. -- reason I want N/A is because I won't ever use 4-5-600 hp. But I will always use ~250. (personal pref I guess, though I have been considering a lower output SC build out just for the fun & simplicity of it)

21psi is the highest I think I've seen. I'm sure there's higher out there.
http://www.ft86club.com/forums/showthread.php?t=59784




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Purely curious. You really think the motor for our platform was built to handle boost? I know the DIT is the same motor for the most part. And that Tada wanted the purchaser to do what they pleased with the car. Just wasn't sure boost was part of his equation or not. Curious for more details from you. Thanks.

I'm on 13 now

Its never gonna happen you can keep dreaming with those numbers and staying NA

No one has enough data to prove one way or another. You gotta pay to play. With a proper tune and the right mods you can reduce your risk. But these engines have proven to pop even under NA. I have driven in a boosted twin(turbo and S/C) as a passenger and I can tell I was giddy like a school girl. Turbo is the best for DD driving.

^ You're welcome :D

I'm at 10 psi on pump and theres no reason to go any higher than that on the 91 we have here. Ill be on e85 soon with a map for 12 psi and one for 14-16 depending on what my clutch can handle without slipping. For safety, its all about the tune and not going crazy high with boost levels

0 if you want it to last any long term miles. These motors just aren't built for these power levels, build the motor and then boost.

I and most of my friends already went down the blown motor road in evos and stis in our 20s. We learned then the smart moves to make when it comes to power. Reports of people with 20k and less miles mean zilch for reliability. When people start hitting 60k boosted miles we will get a better picture, I doubt many will ever make it that far on a stock bottom end.

I know I'm not on stock motor but maybe this will help someone. 9:1 compression, forged pistons & rods. 20 psi, 350whp on journal bearing turbo, 93 octane.

Up next, BB turbo with 93 and E85. Aiming for 375whp and 450whp tunes.

The engine was designed from the beginning to be both NA and Turbocharged. The engine was meant to be used across multiple platforms requiring different levels of power. The major difference between the 86 and other platforms using the FA20 family is fueling and compression ratio.

well i guess my question remains unanswered haha. i guess ill just have to find out

Uhhh what? You've been told how much boost multiple people are running on the stock engine. This platform is still new and we don't know the "safe boost" levels of this motor yet for long term use.

You have also been told that you are out of your mind if you are thinking about running 20psi on the stock internals. Your questions were answered.

and there was other comments stating that plenty of people are boosting large numbers and have had no issues thus far. so its not really a for sure answered question. just very opinionated. thanks

on a fully built motor which is tuned, NA can easily hit ~ (or around) 250. I've seen one dynoed at that. But again, fully built motor and I never said "Reliably".

Besides, why the negative attitude? I mean, what the hell does it matter if I paint my car purple with orange polka dots? It's my car and this makes me free to pop, pay, or play with and for what ever I want. When you buy me a motor, I'll tune it how ever you see fit. :bonk:

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.

Why not ask an actual tuner what would be safe? There are alot of comments that refer to what someone has seen on youtube. Rarely ever do you see any actual street FI data. For the dynos that show 5-600whp on a stock engine, sure the engine survived that 1 pull but how about make those pulls back to back and get some 1/4 times to post up. Alot of times when people say "Yeah I've been boosted with 500whp for 2 years no issues" How many miles is the car actually driven? Is it a year round car? If the car is only taken out on sunny days and good weather or never gets that gas pedal mashed to the floor then that doesnt count for reliability IMO.

Only one person realised psi isn't the right measurement for this as a bigger turbo will flow more air at the same psi as a smaller one, disappointing really.

actually 3 of us responded without using psi.

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You're correct. My response I suppose was based on most common kits out there. However you and some others are correct, the actual amount is purely dependant on what size blower etc.... Also supporting piping, IC and TB etc etc..

That said the folks that have built these motors up and played with various TC/SCs would know best. I still "think" number 1 factor is the tune however. When reading dozens of failures posts seems to always come back to the quality of the tune/tuner...

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.

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

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?

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.

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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

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

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

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!

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 :)

Just curious why you say this?