Low budget SR boost power all the way to redline?

[dongoesby]

Hi, as my S14 -> S14 SR swap is coming to a finish, I like to get a little healthy boost upgrade. I've heard that the HKS actuator is a good upgrade to get even if you are not pushing any boost (it helps to prevent boost spike). This is my first swap and I'm doing everything to have a safe reliable setup without too much money.

The only upgrades I have now are a lightweight flywheel, a Tomei manifold w/ 7 layer gasket, a Greddy over sized oil pan and a 3 inch catback exhaust. In order to have a reliable motor, I'm refreshing the SR motor (changing all the gaskets and apply new RTVs), but with all the hard work, stock motor only hit 220 hp (ideally). I'm looking for a healthy 240whp.

Most people pushing 12psi with only HKS actuator are running lean and the motor stops making power after 5000 rpm. I like to get a HKS actuator, an upgraded fuel pump and maybe a fuel regulator. Do I have enough juice to push a linear power all the way to redline?

PS: all evos and subarus have open ecu, which they can tune their car w/ stock ecu. I highly doubt that we have the same ecu design, but definitely like to confirm if it is a yes or no.

[GSXRJJordan]

Hi, as my S14 -> S14 SR swap is coming to a finish, I like to get a little healthy boost upgrade. I've heard that the HKS actuator is a good upgrade to get even if you are not pushing any boost (it helps to prevent boost spike). This is my first swap and I'm doing everything to have a safe reliable setup without too much money.

In order to have a reliable motor, I'm refreshing the SR motor (changing all the gaskets and apply new RTVs), but with all the hard work, stock motor only hit 220 hp (ideally). I'm looking for a healthy 240whp. The only upgrades I have now are a Tomei manifold w/ 7 layer gasket, a Greddy over sized oil pan and a 3 inch catback exhaust.

Most people pushing 12psi with only HKS actuator are running lean and the motor stops making power after 5000 rpm. I like to get a HKS actuator, an upgraded fuel pump and maybe a fuel regulator. Do I have enough juice to push a linear power all the way to redline?

PS: all evos and subarus have open ecu, which they can tune their car w/ stock ecu. I highly doubt that we have the same ecu design, but definitely like to confirm if it is a yes or no.

SR's stop making torque around 5000rpm to begin with, and horsepower peaks waaaaaay before redline with the stock intake mani/cams. What you get is a very linear powerband though, and great response all through the revs - any gains at the top will be at the cost of low- or mid-range response/torque.

12psi on a T28 with stock MAF/injectors is right about the limit... I stopped at 10psi when I was running that setup. Getting a wideband will tell you for sure.

A high-pressure/flow fuel pump (Walbro 255) is a must with any engine swap, especially if you turn up the boost. With an adjustable FPR you can bump the base pressure to compensate for running lean at the top, at the cost of running rich all over the place. As long as you're not running 'really' rich (like 10:1) you won't have any problems fouling plugs, but you will burn out your cat (if you're running one).

The SR20 ECU is not as advanced as the STI/Evo/Vette ECU's that allow direct tuning through an AccessPort/etc and software - SR ECUs need to be modded to allow Flash ROM tuning, which is why most people use piggyback units (SAFC/Emanage/etc), and anyone pushing real power gets a standalone (Power FC, AEM EMS, Haltech).

[godsmack]

Just an fyi i've had good luck with the same mods except i got a fmi and i do have the hks actuator. i've been boosting the motor at right around 14psi. for 2yrs with no problems except i blew 3 trannys and 1 turbo but the turbo is probably cause i don't run water through mine. But on a serious note get a wideband to measure.

[Z33dori]

T28
boost controller ... set to like 14psi
walbro
manifold
aftermarket o2 housing
3" dp
test pipe
3"> cat back
FMIC

my car had all that but with a t25 on 18psi
dynod 232WHP AND 260FT/LBS

and for safety ... ARP HEAD STUDS AND MLS Head gasket

[dongoesby]

A high-pressure/flow fuel pump (Walbro 255) is a must with any engine (http://zilvia.net/f/tech-talk/257689-low-budget-sr-boost-power-all-way-redline.html#) swap, especially if you turn up the boost. With an adjustable FPR you can bump the base pressure to compensate for running lean at the top, at the cost of running rich all over the place. As long as you're not running 'really' rich (like 10:1) you won't have any problems fouling plugs, but you will burn out your cat (if you're running one).


With that said, an adjustable FPR is only doing nothing good but running rich all over the place?
In order to have a linear power, is a fuel pressure regulator necessary for this setup?

Just an fyi i've had good luck with the same mods except i got a fmi and i do have the hks actuator. i've been boosting the motor at right around 14psi. for 2yrs with no problems except i blew 3 trannys and 1 turbo but the turbo is probably cause i don't run water through mine. But on a serious note get a wideband to measure.

I remember there is a failure case with this setup. A member claiming that his spark plug (grade 6) couldn't withstand the heat and had piston #1 melted down. I assume that you still using the stock spark plugs?
I do plan to get S15 SMIC, and I have Defi oil temp, oil pressure and boost gauge. Do you think I still need a wideband?


T28
boost controller ... set to like 14psi
walbro
manifold
aftermarket o2 housing
3" dp
test pipe
3"> cat back
FMIC

my car had all that but with a t25 on 18psi
dynod 232WHP AND 260FT/LBS

and for safety ... ARP HEAD STUDS AND MLS Head gasket

18psi without larger fuel injectors? what a brave soul. :)
Did you use any management system on that 232whp set up? How did the dyno grahp look like, is it running lean after 5k rpm?

[Z33dori]

no the car didn't lean out that much. But i can't say how bad it was b/c i didn't have Wideband

but the car was fast and felt strong all the way to 7500... i'll look around for the sheet.

I do have a more recent sheet tho.
same set up but on 7psi, much colder weather tho
car did 220whp and 210ftlbs


so, it is safe to say that my car prolly was on the leaner side, but when i did the head gasket swap everything look perfect inside... so... who knows

[midnight_rex]

yesterday i just installed my HKS wastegate on my t25. im boosting at 14psi and only until after 5500 rpm does it stop making power. it feels great on low and mid range. i wish i had a wideband to see if it is running lean.

mods:
HKS wastegate
FMIC
3'' exhaust all the way

my car pulls strong until after 5500rpm. i also have a boost leak which drops it back to 12 psi lol. but all in all it feel much smoother than 7psi

[Z33dori]

exhaust manifolds make a huge diff.

and so do boost leaks! go figure .

[GSXRJJordan]

With that said, an adjustable FPR is only doing nothing good but running rich all over the place?
In order to have a linear power, is a fuel pressure regulator necessary for this setup?

Adjustable FPR = fuel pressure regulator. You can raise the base pressure, but can't adjust the 1:1 gain ratio (1psi boost = 1psi more pressure). If you raise the base pressure to compensate for leaning out at redline, you will be rich everywhere else in the powerband. This isn't a huge deal, especially if you don't run a cat.

I remember there is a failure case with this setup. A member claiming that his spark plug (grade 6) couldn't withstand the heat and had piston #1 melted down. I assume that you still using the stock spark plugs?
I do plan to get S15 SMIC, and I have Defi oil temp, oil pressure and boost gauge. Do you think I still need a wideband?

You should replace your spark plugs anyway, with heat range 7 plugs. But that's not enough to melt a piston, he was probably boosting too much on a stock setup - plugs don't make that much of a difference lol

18psi without larger fuel injectors? what a brave soul. :)
Did you use any management system on that 232whp set up? How did the dyno grahp look like, is it running lean after 5k rpm?

He doesn't have a wideband, so how would he know? I can tell from experience that the T25 is out of it's efficiency range by that point, so no t only do your intake charge temps go up (making each pound of boost after a certain point worth less hp) but each pound is more dangerous than the last lol.




exhaust manifolds make a huge diff.

and so do boost leaks! go figure .

Yeah, fix that shit - if it's at the turbo/manifold junction, you're losing boost and heating up your engine bay, but if it's at the manifold/head junction, you can burn your valves (air gets in and ignities the unburned fuel behind the valve, killing your valve seats).