Interesting read

[KevinA 695]

Guide Naturally Aspirated NA Engine tuning and bolt on intake/exhaust mods for FRS BRZ 86

NA- Naturally aspirated
FI - Forced Induction ie turbo/supercharger
E85 - aprox 85% ethanol based fuel (will vary from pump to pump from about E65 to E85)
Flex fuel Tune- requires a flex fuel sensor - device to detect ethanol content of fuel and integrated with appropriate tuning software can automatically adjust tune as ethanol content changes from full petrol to full E85
CAI - Cold Air Intake.
E85 tune - tune for E85 fuel will cope with variation in ethanol content from about E60 to E90, will not cope with straight petrol, need to reflash back to petrol tune. (or switch maps manually if you have Ecutek)
AFR - Air fuel Ratio.
02 sensor - oxygen sensor

Canned, Off The Shelf (OTS) or Flash and Go tune - A tune done for a specific set of mods - your mods must match tune - cheaper than a custom dyno tune , on NA cars will probably yield 90% or more of possible gains

Custom Dyno tune - tune done on a dyno for your specific car with your specific mods - on NA cars not that much gain over a Canned or OTS tune if your mods matched tune. Turbo/supercharged cars benefit much more from custom tuning.

If you want more than about 35-40 wheel horsepower gain then your going to need to go Forced Induction FI either Turbo or Supercharger, just skip NA mods


Exhaust Mods
Most exhaust mods will make your car louder
If you planning on going catless header or catless or high flow front pipe , get a quiet cat-back or keep the stock cat-back.
The cats are very good at reducing noise and rasp/resonance/drone.
If you remove second cat plan on adding a resonator in its place to reduce noise/rasp/drone.

Most of the power gain in changing exhaust components comes from a catless header, the rest of the exhaust wont gain you much at all.
Hi Flow catted headers will work but slightly less gain than catless headers, generally more expensive due cost of cat.


Dyno numbers
All dyno's read different. To compare results they really need to come from same dyno, or at least same dyno type using same calibration.
You generally get about 15-20% loss through drive-train so a stock FRZ/BRZ/86 rated at 200hp at flywheel will generally dyno around 170hp at the wheels (WHp)
Make sure your comparing wheel horsepower or flywheel (engine) horsepower and not mixing them up. 

Will I get a CEL code
If you go to catless header you will get a CEL code P0420 (cat efficiency) it may thak a while to show up though.
Even some catted headers will still cause a cel code
You can try O2 spacers or de-foulers but they will not always work 100%
The only 100% way is to disable the code in the ECU usually done in aftermarket tunes.

Why you get CEL Code when changing header

Integrated in header is a primary catalytic converter. Their is the primary 02 sensor before this cat and a secondary 02 sensor after it. The ECU compares the reading from both and works out if the primary cat (in header) is working efficiently. If it detects abnormal readings it will set CEL Code P0420.


Changing any other exhaust components other than the header will not trigger a CEL code. Its only the primary cat in the header that is monitored by ECU, secondary cat in front pipe is not monitored



 

This image has been resized. Click this bar to view the full image. The original image is sized 1100x542.

Stock header showing both 02 sensors

Tips for changing header

1. Always use new gaskets, if you re-use the old ones it will leak causing 02 sensors to read incorrectly 
2. Run a thread tap or chaser (M18 x 1.5) through you new header 02 bungs to clean them up , 02 sensors should screw in by hand. If you force them they are easily damaged and the threads on 02 sensor easily stripped.

3. Put high temp anti-seize on header bolts and 02 sensor bung threads, DO NOT get any grease or anti-seize on sensor tips, once contaminated they are stuffed.

4. Leave the 02 sensors in the stock header until you remove it from car then remove sensors. Just disconnect the plugs an tethers on wires as per picture below.

5. Black plug to black socket, grey plug to grey socket. and remember to plug both back in.

6. Use correct torque for bolts and o2 sensors, re-torque after a heat cycle.

This image has been resized. Click this bar to view the full image. The original image is sized 1024x675.

Stock header is is Equal length stepped design , but its not perfectly equal length
see diagram below of stock header with heat shields removed showing integrated cat








Tune only on completely stock car

About 10 wheel hp
Reduced torque dip arround 4000rpm
smoother running
smoother idle

If you run E85 on completely stock car with appropriate E85 tune you can get about 20 Wheel HP gain.



Catback exhausts
Little power gain maybe 2 or 3 wheel hp , just do it for the sound- no cel code problems as your not altering the primary catalytic converter in header.

Catted header (hi flow cat) without tune maybe 5 wheel hp 
you might still get CEL code due cat efficiency
you can try the O2 sensor spacers or de-foulers on the second (rear) 02 sensor but they don't always fool the ecu and you might still get CEL code P0420


Catless Header without tune - 5 to 8 wheel hp
You will definitely throw a CEL code eventually
Again you can try the O2 sensor spacers or de-foulers on the second (rear) 02 sensor but they don't always fool the ecu and you might still get CEL code P0420


Catless header with tune (petrol) around 20 wheel hp
Catless header with tune (E85 fuel) around 30 wheel hp
Catted header with tune (petrol) about 15 wheel hp
Tune will take full advantage of your header
Tune will disable the P0420 cel code - no need for spacers or de-foulers
Tune will further smooth out torque dip
Smoother running, smoother idle


Header types.
Any decent well designed header will produce similar gains on an NA car

EL header is traditional sound for a 4 cylinder 
UEL header is classic subaru boxer rumble , dropped cylinder beat, similar to wrx.

EL header generally produce a couple more peak horsepower 
UEL header generally produce more low/mid-range power/torque but can fall a couple of hp short in top end compared to EL header.

Their is really not that much in it just stay away from cheapo, dodgy brothers, Ebay headers.
Pay the extra for a known and tested header.


Changing the rest of exhaust after a catless header does not yield much more power on NA cars.



E85 fuel.
If you retune you car for E85 you can add about 10 wheel hp gain in addition to mods above.


Intakes CAI short RAM ect
The Stock intake is quite efficient for NA cars
Maybe add a performance drop in filter and an intake tube but best to leave stock airbox and maf sensor location unchanged. Unless you have access to a tune to suit the new intake
or you can do maf-scaling and a bit of tuning yourself

Changing the entire intake ie (CAI or short RAM ect) will require the MAF (Mass air Flow) sensor to be recalibrated via a tune

Their is little power in intakes for NA cars

If you MAF scaling is way off due to your aftermarket intake (or you have an air leak in intake) you can get cel codes due to lean/rich limits
If you MAF scaling is "off" by even 10%-15% it can still cause hesitation or bogging rough running and incorrect AFR.
Just because an intake requires a MAF rescale does not mean its flowing more air, the MAF sensor just samples the air flowing through through the intake.
So if the position of the MAF sensor is changed or the size of the tube the MAF sensor sits in is changed the sample will be different. It does not mean the intake is actually flowing more or less air, just means it not calibrated for that intake.

Beware not all mods will produce cumulative power gains 

eg intake manufacturer claims intake add 5hp to stock car, maybe it does but its possible this is due to intake adjusting AFR due maf scaling errors . You now get a tune which adjusts afr and timing other parameters usually tune would add say 10hp. So you assume with your intake your going to get 15, often not the case.

This can also happen with exhaust mods, your initial mods may produce some gains and the exhaust is flowing better, subsequent mods will have diminished gains as the exhaust now flows sufficiently well for the pumping capacity of the engine.

Crawford power blocks seem to work quite well on stock cars as they alter volumetric efficiency, however so does tuning (adjusting intake/exhaust valve timing), and so does exhaust/intake mods . But the overall gains with all these components is often less than the gains of each individual component used by itself.

Their are so many options its very difficult to predict the outcome.



Cheapest Naturally Aspirated Power Gains


Approx Wheel Horsepower Gains over stock

Canned Tune Only petrol 10 wheel hp

Canned E85 tune on stock car aprox 20 wheel HP

Catless Header plus canned tune petrol 20 wheel hp

Catless header plus canned tune plus E85 fuel 30 wheel hp.


You can do Catless header + canned or off the shelf , flash and go tune on E85 or petrol for about $1000 if you fit header yourself.

That about $30 per hp if your on E85



After that the last 10 hp is going to cost big

To get near 40 wheel hp gain over stock you would have to do in addition to above mods

Intake
overpipe, hiflow secondary cat or catless front pipe
cat back exhaust

Custom dyno tune on E85 fuel.

That going to cost you probably in excess of $2000 extra. ie about $200 per hp, time to think about Forced induction.





Tuning options (ECU flash tuning)

Ecutek
OFT -Openflash Tablet
BRZEdit
Tactrix/Ecuflash 

You can get "piggyback" devices for these cars but we have a flashable ECU and flashing the ECU is a much better option than "piggyback" devices. Piggybacks like Uni-chip work by adjusting the ecu sensor inputs to fool the ecu. They are very limited in their adjustments and require wiring .

Flashing the ecu allows hundreds of tables to be changed to specificly alter parameters and limits. You generally have the ability to flash the ecu back to "stock" in minutes so its virtually undetectable.

Whatever flash tuning platform you use on an NA car you will get similar results power wise with a competent tuner

You can run dedicated E85 or petrol tunes with all options, but an automated flex fuel system is only possible with Ecutek

Dedicated E85 tunes will cope with the variance in ethanol content between fuel company's, but you need to flash back the petrol tune to go back to petrol.



If you want true flex fuel (integrated flex fuel sensor) and map switching on the fly, then Ecutek is your only option at present and obviously that will cost you more.

Flex fuel tune (with flex fuel sensor) will not give more power than a dedicated E85 tune but its more convenient and safer in case you filled up with wrong fuel.



See links below for more info on tuning, logging ECU flashing , E85 ect.


Hope this is useful.
If you find errors or omissions let me know and i will fix it up.

[Guest]

Great reference Kev. Thanks for posting.

[Lauren 2259]

Interesting and a good reference, apart from the Americanisms! 

 

Also there is absolutely no such as a 'Cold Air Intake', it can only ever receive ambient air!

[Mark-in-Stoke 488]

Kevin, Nice find :-)

[Stan Hawrylak 23]

Good article. Expecting a noisy motor this year then

HKS catless manifold and unresonated Milltek cat back system. The only saving grace in noise suppression terms is a Berk catted front pipe. Sound check at TSS round 1 will be interesting...

Will see if I can sound check it before

[Mark-in-Stoke 488]

Stan, fingers crossed mine will be a little quieter, Tomie UEL header ordered, Milltek res cat back fitted yesterday, Cobra o/pipe and sports cat fitting next week, and Takeda air box going in today, then down to Adrian mid Feb for a tune.

 

Just like Christmas

 

I was going to go turbo and all the bits that go with it, I saved all but £1500 and then my wife reminded me that her train and car parking ticket needed renewing, £3900 straight out of my fund  . 

 

Speaking to people with similar set-ups they are well impressed,

[KevinA 695]

Good article. Expecting a noisy motor this year then

HKS catless manifold and unresonated Milltek cat back system. The only saving grace in noise suppression terms is a Berk catted front pipe. Sound check at TSS round 1 will be interesting...

Will see if I can sound check it before

Stan

 

I have a fairly good db meter, if you need a pre TSS check lol

[Stan Hawrylak 23]

Stan

I have a fairly good db meter, if you need a pre TSS check lol

Thanks Kevin. Need to get me one of those or just have Adrian sound check it if he can. Don't want any nasty surprises later. Will see how it turns out, can't be sure but we might be struggling for Croft...

[Special K 442]

Thanks Kevin. Need to get me one of those or just have Adrian sound check it if he can. Don't want any nasty surprises later. Will see how it turns out, can't be sure but we might be struggling for Croft...

 

Stan, I think there is a mobile phone app which does a db meter's job....

 

Also, if anyone is considering an f/i upgrade for optimal track use I would suggest thinking carefully about a new exhaust system - better to go 3inch than 2.5inch is my personal view..

 

Spec K

[rob275 1817]

Stan, I think there is a mobile phone app which does a db meter's job....

 

Also, if anyone is considering an f/i upgrade for optimal track use I would suggest thinking carefully about a new exhaust system - better to go 3inch than 2.5inch is my personal view..

 

Spec K

 

There are apps out there, but they can only read up to 71db 

 

EDIT: Before some nerd corrects me, this is due to phone hardware and 71db is just an assumption based on my current phone that reads up to 73db and my previous of 71db..

[Stan Hawrylak 23]

Stan, fingers crossed mine will be a little quieter, Tomie UEL header ordered, Milltek res cat back fitted yesterday, Cobra o/pipe and sports cat fitting next week, and Takeda air box going in today, then down to Adrian mid Feb for a tune.

Just like Christmas

I was going to go turbo and all the bits that go with it, I saved all but £1500 and then my wife reminded me that her train and car parking ticket needed renewing, £3900 straight out of my fund .

Speaking to people with similar set-ups they are well impressed,

Interested to hear how you get on with the Tomei header (sorry Lauren - Manifold).

It was a toss up for me, Tomei or HKS. I went HKS because Adrian had mapped one already and seen good air. About 170g/sec. They seemed impressed so it would have been a punt go for another type. The Tomei might be better, time will tell...

As for UEL versus EL, I went for EL - slightly stronger top end, torque less important. The car is used primarily for competition plus I have shorter final drive so the priority is top end grunt :-)

Shame about the turbo plans. It does mount up when you add in all the bits n pieces :-) My wife does salary sacrifice to pay for her season ticket, something to think about.... ;-)

[Kodename47 446]

Steve's post from ft86club. He does like his quick guide posts...

[Mark-in-Stoke 488]

Stan, I went for the UEL for the opposite reasons, as wasn't so much bothered with top end. I can't see an outright winner with the EL or UEL as they both do different things.
Looks like we've entered modding season again :-D

[KevinA 695]

Always found this handy

[Deacon 1357]

Mark and Stan you're giving me a lot of manifold envy!

[Mark-in-Stoke 488]

Sorry Buddy, Maybe when you hear them the envy will dissipate   

[Deacon 1357]

Haha! Yeah may be a little loud...

[KevinA 695]

Spanners out on Tuesday

[Mark-in-Stoke 488]

Very nice, but I'll go for this one

 

[Keethos 842]

Get a room you two.....I want one too

[Mark-in-Stoke 488]

Keith, You need to stop getting distracted and get your baby back to looking her best 

[Kodename47 446]

I went HKS because Adrian had mapped one already and seen good air. About 170g/sec. 

You can't tell much by the MAF reading, because a) you can change it and the intake will play a massive part.... even different filters make a difference.

[Stan Hawrylak 23]

You can't tell much by the MAF reading, because a) you can change it and the intake will play a massive part.... even different filters make a difference.

Of course that figure is an amalgam of the system as a whole but it was measured before and after the header was changed, and a good improvement was recorded.

I don't know how good that figure is, you'd have to ask Adrian. But I do know he and the owner were pleased with the results.

Haversack

[JamesP1991 222]

Great and concise info for anyone looking at modding their car. It is tough after I/H/E to get more HP out of the engine effectively if staying N/A and are on a limited budget. 

 

Just going to try and pick and choose further mods carefully now as I really want to stay N/A. 

[griffinnn 11]

If this has just been nicked from ft86 club (it has) you should really credit the original poster.