Jump to content
SAU Community

Recommended Posts

Hey guys,

I just bought a gts25t its pretty stock except for a tip...and really enjoying it. However I am told that I can tune the boost up 2 psi before the computer will stop me. If I did this what gains could I expect? 15kw at the rears?

cheers.

Link to comment
https://www.sau.com.au/forums/topic/323185-2-psi-increase/
Share on other sites

  • Replies 47
  • Created
  • Last Reply

Top Posters In This Topic

if it is stock (stock exhaust, etc) then you won't see that much of a gain from upping the boost by 2 psi. you will see a gain, but not that much, maybe 10kw. you would see a much bigger gain from putting on a full turbo back exhaust and then putting the boost up 2psi. even just doing the exhaust would see a gain similar to what you will get by winding up the boost 2psi.

also the ecu won't start throwing a tantrum until you up the boost by about 5psi, but on stock exhaust a 5psi increase would be stupid.

Link to comment
https://www.sau.com.au/forums/topic/323185-2-psi-increase/#findComment-5268828
Share on other sites

you can expect higher fuel comsumption haha..

on a serious note, you're better off leaving the boost stock and getting a full turbo back & a good panel filter.. more noticable gains.. that 2psi on a stock car, you won't feel the gains.

once you've done that, then wind up the boost to 0.8bar ~12psi then you'll feel something

Link to comment
https://www.sau.com.au/forums/topic/323185-2-psi-increase/#findComment-5269087
Share on other sites

you can expect higher fuel comsumption haha..

on a serious note, you're better off leaving the boost stock and getting a full turbo back & a good panel filter.. more noticable gains.. that 2psi on a stock car, you won't feel the gains.

once you've done that, then wind up the boost to 0.8bar ~12psi then you'll feel something

Would an upgrade of the exhaust manifold be enough?...I don't want it too loud. I think it would be too loud if I did a larger pipe all the way through. Though I could put resonators in. Its sounds just right at the moment.

So I could gain 15-20rwkw with just an exhaust? Sweet.

Link to comment
https://www.sau.com.au/forums/topic/323185-2-psi-increase/#findComment-5269291
Share on other sites

Manifold upgrade won't do anything, the restriction is after the turbo. There are plenty of quiet exhausts around, and if they are still to loud than just get another resonator put in along with a better quality muffler

Link to comment
https://www.sau.com.au/forums/topic/323185-2-psi-increase/#findComment-5269325
Share on other sites

No, A full exhaust, hi flow cat, dump pipe and filter upgrade might see that sort of increase. (don't change manifold unless your changing turbo) But you might not even feel much change.

If your chasing the sort of gain an extra 2psi will produce then I suggest looking into the cars handling first, Ie swaybars, tyre/rims, suspension, Hicas lock bar, castor & camber adjustments, Brakes!etc

You will feel a much better improvement doing this.

Then when the car no longer handles like a boat, look into increasing the power. Change the boost from the stock 5psi to 7 psi @ 4500rpm and make it 12 psi from 3000 rpm or whatever and you'll notice a much more rewarding change.

Just do lots of reading on the forums and you will learn a lot.

Link to comment
https://www.sau.com.au/forums/topic/323185-2-psi-increase/#findComment-5269358
Share on other sites

I had a 3in fijitsubo jasma cat back when i got my gtr with the stock compliance cat. When i changed out the compliance cat to a highflow I got a fairly decent gain, I noticed the turbos would spool earlier and faster and the car felt much happier. Probably +10 killerwasps

Link to comment
https://www.sau.com.au/forums/topic/323185-2-psi-increase/#findComment-5269359
Share on other sites

The 7 on your gauge is in the units of 100mm HG. Just like distance can be measured in miles, lightyears or KM - the units matter (a lot).

760mmHg = 1 bar. Therefore your 7 = 700mg Hg which is ~13.5psi.

A rough way is to double whatever number it represents on the gauge - then you have psi.

Link to comment
https://www.sau.com.au/forums/topic/323185-2-psi-increase/#findComment-5269465
Share on other sites

it wouldnt be running 13.5psi with everything stock???

i dont think they are that accurate my reads seven but i am only running 9psi, been on the dyno so i know its 9 psi... or 9.26psi till 4000rpm to be exact.

on the exhaust side i have a 3" dump decat and 3" trust silent power and i think its super quiet cant even hear it when cruzing so you dont have to have a loud exhaust to make power, i think you should get a full exhaust system before trying to wind up the boost the gain will by far be better then winding up the boost and as mentioned before a K&N pannel filter will give you better gains all over the RPM range then winding up the boost!

Link to comment
https://www.sau.com.au/forums/topic/323185-2-psi-increase/#findComment-5269750
Share on other sites

Many thanks,

I thought 3 1/2 psi was little low for the power it was wacking out. I find my suspension great... almost too tight on the bumpy northland NZ roads.

So what size exhaust is about right to start with? 3" or 2.5"? I am also told that nissans love bigger intake manifolds.

I just got married so money is not really flowing :) but i would like to get the car as a project up to 170kw at the rears if I can do it cheaply, but properly.

Link to comment
https://www.sau.com.au/forums/topic/323185-2-psi-increase/#findComment-5271104
Share on other sites

3" turbo back exhaust, fmic and 12psi will see you up around 170 to 180kw easily.

as for the exhaust being noisey, if you find that you want it quieter after putting on the 3" system, invest in a decent oval muffler. they make things much quieter than cannon does.

Link to comment
https://www.sau.com.au/forums/topic/323185-2-psi-increase/#findComment-5271616
Share on other sites

3" turbo back exhaust, fmic and 12psi will see you up around 170 to 180kw easily.

as for the exhaust being noisey, if you find that you want it quieter after putting on the 3" system, invest in a decent oval muffler. they make things much quieter than cannon does.

As long as you don't hit rich and retard... my 34 when fairly stock was great with 185rwkw @ 13psi for about a month, then R+R kicked in hardcore and it just became a pig from 4.5k-6.5k rpm.

A new ECU or (Nistune flash) should definitely be on the cards - people not looking for big power tend to avoid ECU mods but IMHO they are worth their weight (money?) in gold and give a huge performance / driveability increase throughout the whole rev range...

Just my 2c.

Link to comment
https://www.sau.com.au/forums/topic/323185-2-psi-increase/#findComment-5271803
Share on other sites

As long as you don't hit rich and retard... my 34 when fairly stock was great with 185rwkw @ 13psi for about a month, then R+R kicked in hardcore and it just became a pig from 4.5k-6.5k rpm.

A new ECU or (Nistune flash) should definitely be on the cards - people not looking for big power tend to avoid ECU mods but IMHO they are worth their weight (money?) in gold and give a huge performance / driveability increase throughout the whole rev range...

Just my 2c.

Ya, I have a Z32 chip which I was going to use in my N/A but I will use it in the det instead. Sweet, that stagea sounds like what I am wanting to put out approximately. I hope to do it with a tune and exhaust. We'll see.

Link to comment
https://www.sau.com.au/forums/topic/323185-2-psi-increase/#findComment-5273211
Share on other sites

How much difference between getting a jap exhaust vs a custom one from the local shop?

If you get a reputable performance place to make you up one it will be just as good as a jap exhaust and a whole lot cheaper IMHO. And you'll get exactly what you want.

Just find the right place to do it...

Link to comment
https://www.sau.com.au/forums/topic/323185-2-psi-increase/#findComment-5273518
Share on other sites

How much difference between getting a jap exhaust vs a custom one from the local shop?

didly squat all. what will differ between exhausts though (talking cat back here) is the amount of noise attenuation that the mufflers have (how quiet they make the car). a big oval muffler will make the car quieter than some cannon from supercheap. unless they really cock up the piping when bending it then pretty much all 3" exhausts will flow pretty much the same.

when you start talking about cat converters and dump pipes then things can change a bit.

Link to comment
https://www.sau.com.au/forums/topic/323185-2-psi-increase/#findComment-5273623
Share on other sites

i make 188.5RWKW

3" exhaust turbo back

pod

9psi

everything else is stock

so if you go with a full exhaust 3" good rear muffler oval as said before will quiet it down heaps and air filter upgrade you should be pretty close to your goal and be well under 1k

Link to comment
https://www.sau.com.au/forums/topic/323185-2-psi-increase/#findComment-5273649
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Given you already have the engine cross member to match and likely gearbox mount to. The SR20 has a head start on the RB in this case. They handle GREAT with an SR20, lots of fun.   One I did back in the day
    • have no doubt and wanted too trust me and may regret later not necessarily worried about weight (would be 8 kg ish total) it was more the $$ to do it properly is about $6 - $7K in hardwear need long 310mm stroke jacks etc - plus install and call me whatever im not doing it myself even if wanted too cant weld etc  - thats $10K installed vs fraction of that cost while Ive spent some money on this POS I actually really dont like doing so unless its got a large chance to make me go faster 😁 hey in still carting this things around on a 15 yr old rusted open trailer so I can spend on racing not buy a new trailer to look better the manual jacks Ive had done are heavy and take space but are transportable and usable anywhere - taking or organizing even compressed air let alone nitrogen which is more whats needed coming from Perth to Winton or Sydney or the like honestly just adds to my brain headaches/ hurts of organisation also ha 15 mins job will get down to 2 - 5 min job vs 1 min job for airjacks - all tradeoffs I spose
    • Purely out of curiosity, how do you know all this @dbm7? Do you work with automatic gearboxes professionally? This goes way way way beyond "I've had an automatic Skyline once and did some mucking around"
    • I'll just reiterate that it's best to do all the wiring diagnostics, before even thinking about buying replacement solenoids ~ that is, be absolutely sure the solenoid is bad.....ie; bad connector(s), rodents chewed through a wire, etc etc. If you don't so this, you can fork out all the money for solenoids, only to find something else is wrong (this'll make you cry if you pull the valvebody only to find a broken wire is at fault... ...some more glue on the solenoid packs -- this is the RE5R01A shift solenoid assembly.... ...these are all shift solenoids ~ ostensibly they're the same as the shift solenoids from the 4-speed auto.... ...this is the RE4R01A solenoid set... ...with these, you have 3 shift solenoids attached to the plate, and the separate solenoid is the EPC solenoid (line pressure control) -- with both designs, the TC lockup clutch solenoid (also PWM so they could slide the clutch shut), is located on the lower valvebody half.... ...(story time)...back in the 90's, it was a common fault that the EPC solenoid (or TC-lock solenoid) would fail, but Nissan only sold them as part of the assembly (think ~$350 at the time) ~ thing was, Isuzu also used these boxes in light commercials, and you could buy the PWM solenoid as a separate part, so it was possible to buy/use that solenoid (around $65), and make it fit (remove the circlip, fit to old plate and deal with wiring)...making it a more cost effective repair. I've not seen the RE5R01A shift solenoid assembly, but with the 4-speed RE4R01A it was possible to hack/fit a single shift solenoid onto an other working set, using a donor solenoid from another set with failed EPC....(by rights the whole set should be replaced), but it ends up being a question of how much life is left in the box itself ; sometimes it's a viable repair to fix one solenoid, just to get another 100k of road miles out of it before it needs first overhaul...other times the box is that old/worn, you're as well doing first overhaul and replacing the solenoids and starting fresh... What Nissan did here with the 5-speed, was relocate the EPC solenoid to the lower valvebody (next to the TC lockup solenoid), and stuck the direct-drive clutch solenoid (for the extra gear) where the EPC solenoid used to be on the 4-speed....I can only imagine they did this for serviceability ; the PWM solenoids are most likely to fail, and it's a doddle to drop the pan and change these out (as opposed to dropping the valvebody itself to get at a top mounted EPC)... ...also keep in mind, that some BMW 3/5 series & Mazda (and maybe some Ford/Mazda rebadges, not sure), also used the RE5R01A box under a different name/part number...not saying parts availability is any better, but sometimes it helps to know this when it comes to NOS floating about in the EU.... HTH  
    • FWIW, air jacks are actually pretty light and simple to add, they are just 4 hydraulic cylinders (often at the main cage A and C pillar points) and an externally accessible airline  - they make quick work a breeze
×
×
  • Create New...