Stock FA20 Limits
 

I know I know, this has been asked about a million times but a lot of people have different answers.

Im planing on running a turbo kit (still deciding which one) how much psi can this stock engine hold with premium 91 (I’ll upgrade the injectors of course). I dont daily drive the car but I do drive it a lot on the weekend. :popcorn:

https://media1.giphy.com/media/12aW6JtfvUdcdO/giphy.gif

How much psi can a stock fa20 handle on 91 swamp water gas.... paging @ @ and @ I look forward to this trolling thread.


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I think its about 300 - 350 horsepower before you have issues like cooking connecting rods or shredding 4th gear.

A lot of turbo kits use an appropriately sized turbo for the car and run 7 psi. But if you want to push it, for science, I've read about plenty of people running higher boost on stock internals.

https://www.youtube.com/watch?v=VE9JhiUupY4

It depends on what you want to believe. Most people here will tell you the truth; adding boost at all puts the rods on a timer.

But if you choose to cherry pick what you want to believe, 25 psi is safe and your transmission won't shred gears and your axles will hold

So lets say I wanna run it “safe” at 7-8 psi and then later on buy a built block and turn the boost up. What kit would you recommend

dude .. you can run 26 psi and rape these engines all day... lol


(I had a friend tell me that, couldn't believe he wanted me to take that seriously.. 10 psi on petrol is about the sweet spot but that is going to fluctuate slightly with tune and kit. max 350-360 fly hp)


As someone that's had this debate you are probably debating whether you need the beefier turbo. If so, well. Need 400 or more hp with E85? got ways to manage heat? Is primarily track or at all? Daily drivability an issue? Personally without beefing up the block going anywhere over 360 and near 400 .. total crap shoot how long the rods and head gasket will take it.

Torque breaks rods. Torque from lugging a motor breaks it faster. Torque at low rpms break rods more than at high rpms. Detonation breaks rods more than torque, and the limits of 91 will be reached in order to avoid detonation before the limits of the rods from torque.

For superchargers, most don’t go over 12 psi with 91, and the motor isn’t exactly loving that much boost on 91. For turbos, since torque comes on earlier, unless you do progressive boost, it might be best to limit boost to 8psi.

[QUOTE=Irace86.2.0;3342224]91 will be reached in order to avoid detonation before the limits of the rods from torque. [\QUOTE]


yeah left that little limiting nugget out..

So im just gonna run it at 8 psi, I drive it a lot on the weekends and when I get time off I go to meets the whole time off so if I ever wanna boost more I’ll just get a built engine. Any kit you guys recommend?

I had the same question as you. And decided to go with JRSC three years ago. JRSC would be my decision again today after 35K miles. Initially, I was thinking about a getting a built block and increasing the boost. But the car drives so nice now, I will not touch anything.

Car feels very much normal for daily driving, But downshifting and revving above 3000 rpm starts rapidly increasing the power up to red line. That is so much fun. I think it is safer for the engine that I am not stressing the engine at low rpm.

One negative point (maybe not): Since there is no plateau of the power curve, the upshift especially at 1st and 2nd should be timed carefully before the rev limiter engages. I wish I had a bit higher red line with this kit.

So if you are rev-happy driver, you would be happy with JRSC. If you want to just accelerate at any gear, get Edelbrock or turbo.

It sounds like you're just looking for the answer you want to hear.

You won't find it here.

Neither exhaust diameter, nor kit choice, is REALLY influenced by your parameters.

Your fuel choice puts a hard limit on your power.

Any good kit is fine.


If you are limited to 91 octane then when you build the motor you will want to plan on dropping compression to avoid knock. Probably something around 10.0:1 or less depending on your power goals.

7 psi is different on different turbos.

It's about torque.

I've been running a centrifugal supercharger on E85 at 13psi max boost for over a 1000 miles now. My tuner was happy with all the levels, and honestly it all depends how you drive it.

Mt BRZ makes 340hp at the crank, 310 to the wheels. Torque is 222 ftlb.

So, am I reading right that E85/flexfuel and boost requires injectors and fuel pump upgrades? I'm not really interested in high HP numbers, but I like the idea of running E85 for safety since its readily available where I live.

you need injectors for sure, pump is not mandatory usually but suggested

anyway@BRZ_88 , only 30hp dispersed between crank and wheels is too few at peak power, it s higher

If you're staying NA, I believe you can run on E85 using the standard injectors and pump according to other threads I've read.

If you're planning on going the forced induction route you will definitely need to replace them both to accommodate the increased fuel flow.

Stock injectors with E85 is good to about 280whp it can handle 300whp but it’s close to the limits and advised to change but not 100% necessary. Beyond that you will most likely need to. Always check with tuner and their recommendations. I believe fuel pump is good till about 330-350whp on E85 before necessary.

Yup. I think I ran out of room just before that but tunner wanted extra headroom. Any boost on turbo around 8-10psi on e85 can be done on stock injectors and pump but tuners each have there own ways and preferences.

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Installing JDL kit now with a GTX2867R. The plan is somewhere between 6-8lbs of boost. I can't offer any personal experience yet, but the impression I've got from reading stuff here and talking to tuners, ~8lbs should be "safe". Every motor is different and if it blows up on the dyno, I'll be upset, but not really surprised. My goal (hope) is to stay low boost daily driving for a year or two until I can get a built block that can handle near 400, if I even want the extra power later.

I do know some folks with the JRSC who absolutely love them. I didn't get one because I may want more power later and superchargers have more limitations than turbos.

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I'm supercharged, sprintex s5-210 w/ intercooler kit running 9psi on 93 octane. Have been supercharged for more than 20k miles. When did I supercharge it? 88k. I purchased the car used at 55k without any prior knowledge of initial owner abuse or anything.

Fast forward to today, I have gone through two transmission, and everything else is still running fine. I have mods to help with the FI and I have a very safe tune from Open Flash Performance.

My opinion, I am absolutely tickling the structural integrity of my connecting rods. If i take steps forward towards 12 psi, I would have already bent my connecting rods with this many miles.

So I'm after similar if not slightly higher numbers (320-350WHP) with a supercharger on E85. Seems like Jackson Racing and Kraftwerks have been the most recommended. Are you on stock rods? I don't mind spending the money for better rods if it means I can push closer to 350WHP more reliably. Any other parts besides oil cooler, clutch and rods I should be looking at if I want to push towards 350WHP?

I've been NA and running E85 for months with the OFT flash, no issues here I just use a can of injector cleaners every once in a while.

Only the Jackson Racing kit

6k-ish on the turbo. 257hp at 3k-something RPMs on 93. Seems to be going well, but I did find an uncomfortable amount of metal on my magnetic drain plug on the first oil change post-turbo. Blackstone said I'm probably good. :-) We'll see what the next oil change has to offer...

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2 transmissions both after the supercharger? Damn 2 in 20k miles seems extreme at those power levels.

Possibly the recall?

Not even injectors?

Only the Jackson Racing kit, as in the Kraftwerks it not recommended.

There is no transmission recall

The limits on the motor are as much a question of driving style and maintenance than anything. Stock motors go just from abuse and poor maintenance.

I believe Mike is saying that generally the Jackson is recommended not the Kraftwerks. Check the kraftwerks thread there's been a bunch of problems with belts and tensioners.

Jackson can't think of any issues off the top of my head except for the centrifugal units themselves failing. I've no idea what the failure rate is. I stayed away mostly because of how the powerband is.

Aisin published information that our transmission rated for max 250 Nm torque (184.4 lb*ft)
So no surprise here

Fourth gear is the issue and isn’t the I know enough. Can be remedied with strengthening rebuild.

I’m running a Harrop on e85 and FlexFuel outputting 226kw and have had no issues. You just don’t floor it at low revs in fourth. I do have a spare transmission ready to install though.

Unless your rebuild is strengthening the casing, it's not really strengthening anything.

Guy who just broke his 8th stock transmission (but refuses to do a swap).

Do they just let go all of a sudden? My trans feels fine after 14k Edelbrocked miles.

It probably depends on how someone drives.

As far as I know there is no alternative, not reasonably priced that doesn’t require cutting and hammering, trans for the car.. if there is, and it’s not a $15k sequential, I stand corrected.

Depends on your driving habits (how much sudden load you're putting on the transmission).

in other words: Are you putting it into first from 900 rpm and normally driving, or are you dumping it at 4k rpm and constantly ripping through your gears?
Do you have normal street tires, or do you have super grippy tires while you shift aggressively into high RPMs from lower RPMs.

4th gear is a Common issue due to the single cone compared to triple cones 1, 2, and 3 (one third of the surface area of gears to spread the loads). Doesn't mean gears 5 and 6 are free from this problem. Other parts of the transmission are also not designed to hold more loads, as CSG Mike mentioned.

Mazworks CD009 requires minimal cutting and welding. No real hammering.