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Boosting 1990-2002 USDM Subarus: A Chronological Guide

120K views 149 replies 67 participants last post by  JededaiahSoup 
#1 · (Edited by Moderator)
I'll start from the very beginning as far back as I've ever touched an aftermarket boosted Subaru. We didn't need much in the way of electronics at all way back when. You still don't. All of this info pertains to the now older 90's-02 cars. It doesn't seem like 10+ years ago!

Some folks are making a simple thing way too complicated for the older cars. You don't really need "all the JDM components you can find." I need to put my simplistic view of swaps and the work that is being done out there. Basically, don't argue with me junior. Sit there and read and shut the hell up. This works for superchargers and turbos both. I used all of this same knowledge later with ethanol fuels. With no boost and all the fuel system flexibility, I was off and running down a different trail. The same limits apply but in different respects. Don't outrun your AFR with boost, just like you don't outrun your AFR with too much ethanol.

There's 2 kinds of boosted classic Subarus.

1.) 300hp and less that lives for 300k. There's a few still on the road but not many.
2.) 300hp+ that blows something up frequently (by that I mean yearly, not weekly...)

Most of you working on older scoobs that want to have a little fun are in category #1. That is who this is written for. If you just want to boost your older Subaru and have a little fun then this is a short and concise guide for you on using stock parts. Fab work and mild tuning does you right as opposed to a swap. There's not much tuning to do and you leave the electronics alone. If you like to build stuff and aren't such an electronics wizard, then you are why I wrote this. Stop throwing away good equipment. At the same time, noone ever told you how simple it is to use when done correctly. You don't need a WRX crossmember and never did. It's nice to have, but not required. $2k-ish on quality components and labor goes a long way.

Rules thou shalt not breaketh!

#1) Always pay attention to FUEL! These motors are very thirsty because they are oversquare like our powerful domestic gashogs.

A.) get a walbro 255
B.) An RRFPR is your friend!
C.) That's enough fuel mods to handle 8psi comfortably. Don't worry about big injectors and electronics because this is still just mild boosting. The airflow isn't there to need all that extra fuel. 565s are too big!

Fuel quality is a separate issue. Subarus run lots of timing, not lots of boost. That's why bolt-on turbos were still fast on stock vehicles--they used just marginally more air with just enough fuel from a fuel pressure bump. We augmented fuel and quelled knock with charge temp reduction and plugs. Subarus respond so well to better fuel quality because of their aggressive timing curves. That also gets them in trouble with knock so quickly.

I'm the spoiled bitch that hates using unleaded gas and noodles with his fuel ;). I noodle with the fuel specifically because it fixes problems like knock and lets me run aggressive timing. The other 99% of you that don't have that option have different tools at your disposal.

#2) Charge temp reduction is your best friend outside of fuel quality. Most of you are still on unleaded gas. Charge temp reduction is probably weapon #1. Intercooling is a requirement, not an option. On alcohol fuel it's a different story, but for the rest of you petrolheads it's a requirement. Get a good quality intercooler!

#3) Cold plugs and a slightly tighter gap. Removing more of that heat in the combustion chamber is a good thing. Colder plugs also help top end performance. Charge cooling, low boost, and a happy compressor lets you run lots of timing SAFELY on pump gas. Colder plugs remove heat from the combustion chamber and transfer it to the cooling system. You will notice your heater running a lot warmer when in use. Cold plugs may also be a little grumpy below freezing but just until it warms up. Just dropping one heat range can reduce combustion chamber temps that much.

#4) Don't shoot for sky-high boost levels. This means don't overwork a small compressor you found in a junkyard. Stay at 8psi or less and you'll always be happy and never left stranded. A VF turbo is probably the best bang for the buck on home made combos. These engines breathe better than you think, even on older heads. You are selling your combo short with a td04. They still run hot even on a modded older motor. A 2.5-3in DP also works wonderfully. If you want to build something from scratch, then do it right.

#5) Sorting electronics can be a pain, but then again you should see a Honda swap. Where do you go with all of the options and model changes? Sometimes, the answer is nowhere. Older cars are one of the vehicles you can do that with AND get away with it! Keep the MAF in front of the compressor and everything else falls into place. Fuelling is handled mechanically and timing is left alone. Don't run a stupid boost setting and you'll drive happily. Most new WRX owners jump too quickly into the electronics. There's actually a heck of a lot of flexibility in there already, even on OBD0! 300hp on a stock ECU is a no brainer IF you know the mechanical side of things that supports it.

#6) Do not pressurize the emissions lines! Those vent tubes from the valve covers and straight out of the crankcase need to see vacuum and only vacuum. The PCV valve is fine but everything else needs to see vacuum, preferably after running into a catch-can.

#7) Specifically for superchargers.
A) 180D of belt wrap
B) Use tensioners!
C) Make sure the belt alignment is spot on.
D) Make sure the supercharger alignment is spot on. (C+D are for longevity and maintenance sake.)
E) Always use a recirc valve.
F) Relocating the TB is worth it!
G) When you add an exhaust, get ready to add fuel. Boost may drop but they get even thirstier at WOT! Instead of 2-1 on the RRFPR, you might need 4-1 or 6-1 depending. There's enough wiggle room here for <50% ethanol blends, too.

8.) Mind the little things! When you change your fuel pump, change the filter sock, too! Don't boost an engine on old spark plugs. BTW, you will go through plugs marginally faster. 100k on plugs is "possible" but isn't smart. Older Subaru engines are awful about carbon. Tune up the car before you boost it with new filters, o2 sensors, and an oil change. Make sure you have a good timing belt and pumps.

9.) Don't use an N/A Borla header on a bolt-on turbo kit. They're ok on superchargers but EQ headers are always the way to go.

10.) A stage 1 clutch will always do fine for 8psi setups. Don't do 4wd burnouts or hard launches and your clutch will be fine. Too stiff of a clutch plate kills the hydraulic clutch cylinder quicker ($300+ part).

Boosted USDM combinations that work.

You can actually save some money here but strategy changes. A good welder is your friend. Swapping the crossmember and exhaust manifold can work on dual port engines, allowing for a motor upgrade later still under the older stock electronics. This guide covers all 1990-2002 Subarus.

Turbos--do it right and get a VF or 16g. The stock 2.0WRX turbos are too small. T3-T4s are almost too big for such low boost levels. t28s and 13ts are to small. VFs are the happiest, IMO.

Superchargers--don't go smaller than a 300hp capable blower. No M45s. Stick to M60, M90, 1L+ twinscrews, or smaller centrifugals. Rotrex's felt good, but a roots or a twin screw just feels better. All the same tuning rules still apply. Always use a recirc valve and relocate the throttle body for better response. 6-8psi will definitely do you right. Clearing the ABS with a sidemount is a pain. I went for the throat and got new P/S lines. Between us, poking the blower out of the hood just isn't a big enough fad yet but it's coming :p ;) :lol:. I <3 u Spud!

1.8T--the little sleeper that could.

It used to be cheaper and easier to build a turbo system to fit these older cars. The 1.8s were high compression and dual port. High compression and boost is a different ballgame. 8psi with intercooling, cold plugs, and plenty of fuel was a hoot in AWD or FWD. It made about 200whp in a 2600lb chassis that was fun and quick. An SAFC or Field worked fine for bigger injectors. SDS secondary injectors were just two pots to adjust like a radio dial. You could pass emissions easier with secondary injectors instead of big primaries.

These motors like good fuel because of their aggressive stock timing curves and compression. Remember that spark timing and fuel play more of a role in power than boost on a Subaru. E85 didn't come into the picture until much, much later. SOHC heads, a 2.5L STI block, and plenty of fuel with still run on a stock 1.8L ECU.

Mounting a supercharger to this block and manifold is a PITA! Phase 2 heads and manifolds let one literally FALL on the car when done right.

2.2--single port.

More worth the effort to turbo than you might think. Just remember the above listed rules with low boost and proper tuning. $1500ish can do a lot and complete the entire system. The electronics are just as basic as the 1.8. 180whp is not out of the question. 12psi is workable because of the lower stock compression.

'98 DOHC

Same rules still for the electronics. The computer is still just dumb enough to let you get away with boost. Higher compression becomes a problem because of fuel quality that limits boost. 8psi is still plenty of fun that gets down the road. Timing retard is helpful for 8-12psi.

'99 SOHC MAF

Same rules, still! Keep the MAF in front of the turbo and keep it fuelled. RRFPRs work great with low boost clear up until +01. This is also where supercharging gets easier. The manifold is the key part and lets you mount anything on the side of the motor. Clearance issues pop up like power steering lines, injector bodies, and ABS lines. Timing retard is helpful for 12psi.

00-01 SOHC MAP

THIS is where the ECU rules change and get progressively more complicated. 10:1 compression is pretty much "THAT" limit for boost and pump fuel. You also have to get around the MAP sensor that hates seeing boost. 8psi is again the happy zone for the motor. Timing retard will let you get to 12psi safely.

02+--why you shouldn't do it and you're on your own from here...

Simply put, 2002+ N/A engines have pistons that can't handle much boost. Those of you that have managed to get them to live are all under that strict 8psi limit and managed to fool the electronics just right. 4-6psi is about all you can really get at safely. That's less of a return for the effort. I got out of boosting older Subarus around 2002 because of it. Who wants to repair all those failures? It's best to just NOT boost these. That doesn't mean other avenues aren't open like E85 and nitrous.

I'll always advocate a fuel swap for 02+ N/A cars. They respond better to the E85 fuel change than older cars because of their higher compression and aggressive timing curves. Get a Walbro and rrfpr OR 440s and you're good for E85. Colder plugs does these right, too.

Beyond 8psi, the hairy edge.

Like taking chances? Good. Me too.

8-12psi is about as far as I ever went with old school scoobies and boost. 8psi is 50% more air, that's why it's so healthy on a high compression engine. You can also work below 8psi on stock injectors with very little work. Fuel quality and quantity becomes paramount at this level. 440s-565s or secondaries are required. This is how you break 300chp. 8psi or less is still a healthy 220-250chp and won't break your clutch or transmission. Everything I listed here also tunes for torque. 12psi can incinerate your clutch or break a diff. It's also the very limit of 91 pump gas on these older motors.

That's all I've got for now. I wanted to write all of this down before I forgot more of it. :Gost:
 
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#5 · (Edited)
1.8T--the little sleeper that could.

It used to be cheaper and easier to build a turbo system to fit these older cars. The 1.8s were high compression and dual port. High compression and boost is a different ballgame. 8psi with intercooling, cold plugs, and plenty of fuel was a hoot in AWD or FWD. It made about 200whp in a 2600lb chassis that was fun and quick. An SAFC or Field worked fine for bigger injectors. SDS secondary injectors were just two pots to adjust like a radio dial. You could pass emissions easier with secondary injectors instead of big primaries.

These motors like good fuel because of their aggressive stock timing curves. Remember that spark timing and fuel play more of a role in power than boost on a Subaru. E85 didn't come into the picture until much, much later. SOHC heads, a 2.5L STI block, and plenty of fuel with still run on a stock 1.8L ECU.

Mounting a supercharger to this block and manifold is a PITA! Phase 2 heads and manifolds let one literally FALL on the car when done right.
Great write up man, I'd like to add a little from my experience as well.

The bold items are the keys to making this a successful build.

I want to stress on ignition timing control above all things when building these little shortblocks for boost. Ignition timing is originally high on these engines because they're specifically made for fuel economy, but when boost is in the mix, the result can be detrimental. In the old days of boosting these engines, pistons have melted and ringlands have cracked becuase of poor or no timing control.

The next thing is fuel quality and fuel support mods, relative to timing, which helps to achieve the correct AFRs and EGTs for boost.

Cooling, whether its upgrading your radiator, adding an intercooler in general or even a front mount, colder plugs, and an oil cooler. Remember, these engines weren't built for boost to begin with so try to extract as much heat out as possible in relation to how much power you make. Keep the engine lubricated internally at all times. More power requires more mechanical energy, more energy creates alot of heat. Reduce it.

Lowering static compression ratio helps give you some headroom for boost and is done by swapping heads as stated above and/or using thicker HGs.

Boost, the word we all love, is dependant on your tune and supporting mods. READ: If your tune and supporting mods CANNOT handle the extra air going in your cylinders, DO NOT, REPEAT, DO NOT turn it up and assume it will be okay because it won't!!
 
#7 · (Edited)
Great write up man, I'd like to add a little from my experience as well.

The bold items are the keys to making this a successful build.

I want to stress on ignition timing control above all things when building these little shortblocks for boost. Ignition timing is originally high on these engines because they're specifically made for fuel economy, but when boost is in the mix, the result can be detrimental. In the old days of boosting these engines, pistons have melted and ringlands have cracked becuase of poor or no timing control.
True, sorta. Hot days, high boost, and bad fuel killed a few of them. All procedural mistakes, IMO. No intercooling and underfuelling is almost instant death. So is 85 octane gas.

The next thing is fuel quality and fuel support mods, relative to timing, which helps to achieve the correct AFRs and EGTs for boost.
Some think boost is indicative of timing when it's a reciprocal relationship. Timing also affects turbo behavior. I eliminate that notion with a blower. My .02.

Cooling, whether its upgrading your radiator, adding an intercooler in general or even a front mount, colder plugs, and an oil cooler. Remember, these engines weren't built for boost to begin with so try to extract as much heat out as possible in relation to how much power you make. Keep the engine lubricated internally at all times. More power requires more mechanical energy, more energy creates alot of heat. Reduce it.
Troof! That's what makes E85 work so well under boost. It can absorb heat all day long. Colder plugs transfer the heat to the head and the cooling system. Having the heat out of the combustion chamber is good but it always goes somewhere. Removing heat from the charge air and the combustion chamber makes for a happy Subaru.

Lowering static compression ratio helps give you some headroom for boost and is done by swapping heads as stated above and/or using thicker HGs.

Boost, the word we all love, is dependant on your tune and supporting mods. READ: If your tune and supporting mods CANNOT handle the extra air going in your cylinders, DO NOT, REPEAT, DO NOT turn it up and assume it will be okay because it won't!!
[/quote]

Lowering compression is an option but not a requirement. It's an option to relocate the throttle body, too. A Recirc valve is a requirement, IMO. There's work to do to make it to live and more work to run better. Timing is a factor in emissions, but I've always believed these motors like a lot of timing for torque. E85 works well with that skosh more timing that may have been harmful on 91.

Pump gas always seems to have these precautions to not make it angry. Ever notice that? You can't run too much charge heat, even though an octane test uses charge heat to piss off the fuel on purpose. Leaded fuel was developed against that kind of testing. You can't use too much timing and there's never much power to be had with it. Why does unleaded gas suck so much? E85's detonation resistance has saved my ass many times and performed where unleaded pump gas couldn't.

Glad to see some thinking going on. I wanted to post all this stuff before I got too senile and forgot all of it. All of these motors regardless of boost type have common issues like fuel quality, lots of timing, and higher compression.

Lastly, E85 fixes a lot but does create water in the crankcase on turbo cars. I never figured out why my n/a car didn't do that other than short emissions lines and direct vacuum.
 
#10 ·
RSC, how would you compare an 8psi boosted EJ22 from a 99 (MAP) to a 205 swap? What is the stock boost on the WRX's? Just curious. I'm in California so doing anything legally usually requires a swap, ecu and all but I may not live here forever ;)

Nathan
 
#11 ·
watch those head gaskets on the older blocks, I replaced my 00 sohc head gasket at 140,000 km. 30-40 thousand Km later I built my turbo kit at 5psi and the Head gasket went again :( Boost didn't help.

Now at 180,000km Same turbo kit new sti bottom end more boooost!!

Clean write up!

Building Rs-t's is fun and a great learning exp.

Happy boosting!
 
#12 ·
SubieNate--The lower the compression the more you can get away with. A 205 at 14psi is no comparison. Those are much quicker. Boosting an older Subie nowadays involves a swap or working with what you've got on the cheap. The nice thing is that you could put just a 2.0L short block under old school heads and keep everything you just built.

You always end up doing some kind of maintenance anyway. It's best to do what you know you're going to need to do first. Turbo pipes can make the passenger rear cam seal a real pain. I have to do a kitchen sink very shortly at 105k. Maintenance bites everyone eventually.
 
#30 ·
I Never Noticed this Nice write-up.

Not sure what a ej205 with a td04 @ 14psi runs in the 1/4 mile in a GF OBS wagon but my 1999 single port ej222 OBS ran 13.31 in the 1/4 @ 10psi of boost with a running weight of 3050lbs with me in the car.

I've been boosting this wagon since 2004 using a HKS EVC to switch between my 4.5psi base boost level & my high boost setting.
 
#14 ·
I myself haven't seen EJ20 NA motors before either, but I would think the principle is the same for boosting any EJXX NA motor.

Also, when swapping cylinder heads, its a good idea to replace the seals before using them. Especially if they have a good amount of miles racked up.
 
#16 ·
So I guess the question I have is....

1993 Impreza L (1.8L SOHC Dual Port) SWAPPED to a 2.2L SOHC Dual Port from a 1990 Legacy...just used the 1.8 I/M and plugged the EGR line.

M90, mounted in place of the airbox.

TMIC from a WRX(stock TB location)

Now, will my 1.8 ecu handle a M90 on 5-6psi?

What wiring is involved?

More importantly...will my 200k 2.2L bottom end hold up to 6psi?

If so, will it make it 50k miles or 3k miles?

Lastly, how do I adjust timing on a car that doesn't have a knock sensor and has a coil pack?

I understand low charge temps/ cold plugs/ oil cooler...But what about running a Meth/Water injection kit on that TMIC? Will I increase my motors odds of longevity?(assuming the meth/water doesn't crap out at 6k rpm under 6psi)

any help would be greatly appreciated...

:projectsti.com:
 
#23 ·
Signs of life, but is it intelligent? :p ;)

I'm not promising you anything with a 200k bottom end :p. You have something that likes the next gear as opposed to liking redline. They do go 300k+, though. Get it plenty of fuel like the rest of the others. Yours shouldn't need the timing adjustment as a precaution or even water meth. Add fuel with that intercooling and you're good at 5-6psi. Enjoy. 02+ ECU behavior, fuel quality, AND piston machining are what does them in. It's a combination of things preventing them from being boosted as easily.

I like 1.8 ecus for being dumb with lots of timing advance. Well built stuff can still go under these ECU combinations. You can run up to 18psi of boost on all of them just like the factory stuff. It's just more time consuming to get it right.

The 1.8L ECU has an aggressive timing curve. Water/meth in theory does fine on any combo. I've always hated their required and untimely upkeep. BTW, you can't run water/meth through an intercooler. Place the nozzle downstream of the intercooler. THIS IS ALSO NO SUBSTITUTE FOR A LEAN AFR! Detonation is more often caused by a lean AFR than bad fuel quality. Quality and excess heat are tied for second in what is a 3-way battle to kill your engine! Keep all of them from winning that battle!

I've pushed for more focus on available ECU timing and fuel quality because it helps so much. They are SO happy they break transmissions, diffs, axles, clutches, etc. 250hp on 8psi is a snap with good fuel...a snap of something ELSE vital ;). The only reason you need to retard the timing at all is available fuel quality, not necessarily a "fault" of too much timing or even the pistons. 5-6psi you don't really need timing retard. The mix of defensive measures and appropriate tuning change per year range and with how much power you want. I tried to highlight those differences.

Plan it right and you can take advantage of aggressive timing. Stop the pinging anyway you can. I prefer prevention. The settings are aggressive enough in these combinations to see gains from good fuel. Water/meth works in favor of more timing but only to a point. It will always be a band-aid, IMO. Heat is the straw that breaks the camel's back. Intercooling is more reliable than water/meth, even though you could run water/meth with no intercooler.

BTW, these combinations are still thirsty like any other boosted subie. If you go from a catted downpipe to a catless or from a stock airbox to a hi-flow unit, you're going to need more fuel. The most gains to be had with a scoob are really from airflow, not boost. Better airflow also restrains detonation from better temperature control. With that improved airflow comes the demand for more fuel, though. So, again, never forget the fuel...

Trivia: A 600hp/tq Subie on E85 going around the track at full blast gets approximately 2mpg. Yes, 2mpg.


etc..

A turbo and supercharger? You're on your own, like everyone else who has tried it. These are best as "geeky" combinations. One or the other. 5psi from either will hopefully keep you entertained. 5psi won't take all of your money and demand alimony. It can also be reliable and enjoyable for the life of the car. Keep the boost low and learn how to tune the engine. I get creative because I can and know how. Everything you're reading here is what was first shown to me boosting the older cars. The ones still on the road all still follow these same basic rules. You can just get in and go. It's boost without the babysitting.
 
#20 ·
02+--why you shouldn't do it and you're on your own from here...

Simply put, 2002+ N/A engines have pistons that can't handle much boost. Those of you that have managed to get them to live are all under that strict 8psi limit and managed to fool the electronics just right. 4-6psi is about all you can really get at safely. That's less of a return for the effort. I got out of boosting older Subarus around 2002 because of it. Who wants to repair all those failures? It's best to just NOT boost these. That doesn't mean other avenues aren't open like E85 and nitrous.

I'll always advocate a fuel swap for 02+ N/A cars. They respond better to the E85 fuel change than older cars because of their higher compression and aggressive timing curves. Get a Walbro and rrfpr OR 440s and you're good for E85.
Is this pertaining to a > 2001 RS with a phase I EJ251 compared to a phase II? DOHC vs SOHC? Did subaru decide to cheap out on na pistons post 2002?

I've read about the ej251 having "glass pistons", and was just wondering if the prior years really do have better pistons...
 
#27 ·
Everything I have referenced is for premium pump. Upwards from there are more gains from good fuel. E85, 100, or 104 is what I had in mind for better fuel. E85 is everywhere around here but not so in other parts of the country. Good fuel lets you take advantage of the aggressive timing presets by making more torque.

8psi on high compression would be the comfortable limit of pump gas. Lowering compression lets you run more boost. That rule doesn't change. For those looking for more, you indeed can run up to 18psi just like any other boosted factory scoob. Controlling injectors larger than 440s is the problem. 565s don't idle well on the stock ECUS. It's also easier to graft secondary injector controllers onto older ECUs. The right equipment under these older ECUs can make 350-400hp still on the stock ECU. Boosting the older cars teaches you all about the mechanical side that the WRX n00bs sorely miss. It's not all about who you paid to "tune your map". It's about the parts you use.

Thank you ALL for being genuinely interested and not a bunch of spoiled trustifarians. You will gain more confidence and knowledge to work on, repair, and modify your own vehicle while said trustifarian runs up his cellphone bill with his "tuner".
 
#26 ·
Good writeup. I agree with it based on my turbo'ed EJ25. I however have a low compression build and have been running 12 psi for a few years (up from 8 psi for a few years previous) and it is still very healthy. So healthy it destroyed 3rd gear in my transmission last month. I'm using an EJ22T ECU to control the motor, so there has been very little tricking of the ECU to make it run, the ECU knows what boost is and how to tune for it. I am making the switch to standalone EMS soon and am planning to run nearly 15psi, I am confident the motor can handle it.
 
#28 ·
In your experience, with a solid tune, what are the first parts to fail in a hybrid turbo motor? As I said a couple posts back, I'll be going for 15psi with a solid tune on my low-comp motor build using EJ22T/EJ25 internals. I have heard the EJ22T rods are the weakest link. Of course my block is open deck, but I don't usually see people cracking their piston sleeves very often.
 
#29 · (Edited)
Further ramblings...

You could cruise around on wastegate with a happy commuter and save 15psi for when you really mean it. Think about the sources of heat and how often you really need to use them. Cruising around town, you don't need scramble boost. Even 15psi all the time kills them quicker. If you want 100k from it, then go for it. If you want 300k from it, learn to use wastegate boost.

You also really can tickle 500ft/lbs on vf turbos at 18-21psi but the transmission and engine don't last. The top end also sucks. A 6spd or built auto is required for that. The ones on 5spds that live are smart about it, honestly. The mountain of torque is in the midrange where a rally car needs it. It's a very solid midrange punch that is eager to get to the next gear. Even with good fuel the engine still takes a beating. That's also the hairy edge even with good fuel. It's not possible on pump gas, IMO. 0-150mph on a REALLY well tuned combination happens in about 20 seconds. Low boost on pump gas takes about 30 seconds.

Any intercooler or fuel really HATES 400F discharge temps. Overworked compressors are the #1 source of intake heat. 14-18psi on stock turbos is where it performs optimally when pushed hard. They are quite happy on lower boost levels, too. When you ease restrictions of stock top mount intercoolers, use a bigger downpipe, or port the stock header, then every boost level performs better. Two things piss off a WRX owner that just lost to you: the fact that you are on less boost--or worse--no boost at all...

Easing airflow restrictions reads as less boost when done on the intake side. The air is going in easier. On the exhaust it can raise or lower boost levels depending if there was a restriction before or after the turbo. You guys with bolt on kits to USDM n/a wishbones should heavily consider header port work at the exhaust flange. That pressed fit pipe is horrible for exhaust flow. Headers with this mod have no carbon deposits in that area other than a film of soot. Where carbon builds up in chunks is where soot and fuel have been collecting, like every stock header has :unamused:. When fixed, the exhaust pushes more efficiently against the turbine. It improves scavenging of the cylinders and lowers operating temperatures. Little detailed stuff like this is almost more like "grooming" the combination than "tuning" it.

When you work on all of these little inefficiencies, power goes up without really stressing the motor or turbo. More boost means squat next to more airflow. Newer stress levels goes to the driveline instead. The target boost levels you used to see now perform more efficiently and lag virtually disappears. There are lots of gains to still be had in part throttle, mileage, and turbo response. If anything increases on a dyno, its torque. What comes easier is drivability and the next gear you need :).

Consider yourselves on notified, too. We're about to unveil our complete modular water intercooler systems. A few heat exchanger frames went out the door quickly for custom projects already. SEMA in November was wonderful. We are about to be able to ship the same day for most of our newer completed systems. Announcements were to wait upon reaching that point and we are there this week. People are very capable of assembling their own water intercooler sytems. Making a quality heat exchanger was always the most challenging part of the job. We took care of that while still addressing a tinkerer's needs :). No more welding up a box that can't do the job efficiently in the first place. You subie heads won't be forced to cut your firewalls for iced intercoolers anymore. There's tabs and bosses incorporated into the designs. The inlet/discharge castings are universal and can be rotated different ways on the assembly. Our 600hp capable heat exchanger is still only 1.25in. tall! At this point a subie is still my faster toy of choice. Decisions decisions...

Booyah! ;)
 
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