G25-660 sr20

Kieranps13

Kieranps13

Member
Welcome to my thread on the process of installing a g25-660 turbo on my Nissan Silvia ps13 club ks with the stock red top sr20det engine.
So a rough spec on the car how it sits now
Stock engine as far as I'm aware
340 lph fuel pump
Blitz front mount intercooler
Hks intake
Stock turbo
3 inch turbo back exhaust
Gfb boost controller set at stock boost pressure
Standard injectors
Standard ecu and tune
And I think that's it so the car in this form made 225hp and 224lbft at the wheels which is not bad and is totally healthy.
I've don't a fair few miles on this set up I don't use it for drifting not that it doesn't do the occasional skid but it is just a road car for me to enjoy and I hope to do a few track nights as I live 30 mins away from knockhill.
So my plans for this winter are to install the g25-660 it has a .92a/r housing so is a bit bigger I have my reasons for this size I have also got a Walton top mount manifold to mount it to and a turbo smart 45mm wastegate I will be running a link g4x plug in ecu and will go mafless I'll also be running id1050x injectors and a radium top feed fuel rail the engine will remain standard internally for now but I won't be trying to push it to its limits and will have fail safes in place to protect the engine. My goal with this thread is to try break down what's all needed and possibly the cost of everything thanks for taking the time to read and there will be updates to follow.

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So exhaust side hot side turbo system whatever you want to call it. This is where I'm starting as this is where the most money is involved. I got a garret g25-660 with a .92a/r turbine housing I decided to choose this turbo in particular for a couple of reasons. So I know everyone seems to love the 550 version but to me this turbo is to small yes they make power on built engines but in my eyes no matter how well they flow they are still a small turbo so will create a decent amount of back pressure and effectively strangle the engine. I have also seen a few examples of 550s disappointing people by not making the horse power they expected and have heard it being blamed on not upgrading the cams this doesn't seem to be the problem to me as sr20s have been known to make high 300s and into 400 with stock cams yes upgraded ones will make a difference but to me the problem is poor sizing choice of the turbo when stock engine sr20s can make 400hp and have been for years. I'm not an expert and don't claim to be but that's just my analysis so for me it was the 660 with the .92a/r turbine housing this will hopefully still be relatively fast spoiling with a long power band right to redline. My thinking is with it being larger and inevitably slower spoiling it won't have that instant hit of torque which is what destroy engines and gearboxes. This size turbo should also give me some head room for when I eventually get the engine forged as I say I'm no expert but that's just my thinking .
The next thing is wastegate I went with a turbo smart 45mm wastegate only reason I chose this was it was the one recommended by turbo smart. It has the 7psi spring installed which I think should be about right as I'm not going to be running mad levels of boost as it is still a stock engine and want to keep it reliable.
How will you mount all these amazing parts I here you say well with another amazing part that being a Walton motorsport manifold I have heard nothing but good reviews for these and they are expensive but also come with a lifetime waranty and the quality is mega.
I will be running a blitz intercooler which is already on the car. A custom down pipe and screamer pipe and will be making up an lines for oil feed drain and coolant lines I will also be doing some heat management with funk motorsport turbo blanket wastegate blanket exhaust wrap and gold heat sleeving for the lines.

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Long update/thread revival

So basically just ended up diving the car on stock forum for the whole of last year as needed to save up more funds to get the rest of the parts I wanted and also wanted to use the car. Anyway I now have been working on the car for the winter and have made a good amount of progress I have the turbo I stalled with an lines made up and started it for the first time this week. Its going up for exhaust work next week which when done I'll start on the fuel side of things then hopefully of for mapping in April. So basically have all the parts for the car I had to relocate the power steering reservoir to behind the head light think It must be bigger due to being a hicas one. I purchased the 5-0 ignite trigger kit to replace the oem cas which when I had the car on dyno for baseline power runs was looking tired so will be interesting to see how well it works as seems alot easier than other trigger kit options I'll try keep up to date on updates and sorry to anyone who was following the thread

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Quick update on the car I relocated the battery to the boot,wired in the iat sensor for the link ecu and have installed the radium fuel rail and have it all plumbed in with an lines. I have the dyno next week so needing to pull the finger out and finish all the small jobs will post an update next week hopefully with power figures and not needing to rebuild the engine
 
Kieranps13 said:
So exhaust side hot side turbo system whatever you want to call it. This is where I'm starting as this is where the most money is involved. I got a garret g25-660 with a .92a/r turbine housing I decided to choose this turbo in particular for a couple of reasons. So I know everyone seems to love the 550 version but to me this turbo is to small yes they make power on built engines but in my eyes no matter how well they flow they are still a small turbo so will create a decent amount of back pressure and effectively strangle the engine.
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That was quite funny to read, considering the G25-550 and G25-660 share the exact same hotside. Effectively, you’re now increased your emap (backpressure) even more due to a higher flowing compressor.

Lower inlet pressure, higher emap pressure.

G30-660 would have been a much better choice with a smaller AR rear if you really wanted to reduce back pressure
 
Jay1017 said:
That was quite funny to read, considering the G25-550 and G25-660 share the exact same hotside. Effectively, you’re now increased your emap (backpressure) even more due to a higher flowing compressor.















Lower inlet pressure, higher emap pressure.















G30-660 would have been a much better choice with a smaller AR rear if you really wanted to reduce back pressure
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Glad you got a laugh mate as I said multiple times I am most definitely not an expert but I was just going with what I had seen at the time which has paid of as many a people have been disappointed with the g25 550 not producing the number they want and then it being blamed on other things my car has now been mapped and made 372 bhp and tourge was capped at 325 it actually did one run where it made 390 but was dialled back as a safety messure it still makes full boost low in the rev range not as low as stock but very drivable and will also be very capable of producing far more power if I decide to build the engine as it only is only at 1.2 bar
 
Kieranps13 said:
Glad you got a laugh mate as I said multiple times I am most definitely not an expert but I was just going with what I had seen at the time which has paid of as many a people have been disappointed with the g25 550 not producing the number they want and then it being blamed on other things my car has now been mapped and made 372 bhp and tourge was capped at 325 it actually did one run where it made 390 but was dialled back as a safety messure it still makes full boost low in the rev range not as low as stock but very drivable and will also be very capable of producing far more power if I decide to build the engine as it only is only at 1.2 bar
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I don’t mean any harm of course, it was just ironic that you ended up doing the opposite! :D

Those number are ok… Not a lot of boost in it which is the upside but also achieveable on a lot of cheaper turbos.

Do you have a graph to share so we can see what boost response is like? I’m curious.
 
Update on car it managed to make 372whp and 325 lbft of torque which is pretty spicy this was only at 1.2 bar and very Conservative timing it's still makes boost low in the rev range and is by no means any worse to drive than stock it's very manageable doesn't try to blow the tyres of to badly and I would consider it to be a pretty perfect setup for the street the car still has alot to give and I may build the engine in the future and see what it can really do I'll continue to update with small thing to make further improvements on the car also forgot to mention we had some problem with the boost solenoid I don't know anything about tuning but it wasn't allowing a large window for adjustment or something basically it wasn't allowing him to add boost into spots to flaten out the power band a bit or something not to sure but a new mac valve and it should sort that out and hopefully make the power curve flatter
 
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Jay1017 said:
I don’t mean any harm of course, it was just ironic that you ended up doing the opposite! 



Those number are ok… Not a lot of boost in it which is the upside but also achieveable on a lot of cheaper turbos.



Do you have a graph to share so we can see what boost response is like? I’m curious.
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No worries it seems to be doing its job in fact on the dyno the manifold was barley glowing so it must be flowing well enough yeah I do have a graph I'll have to ha e a look for it and I'll post a photo on my last update. Yeah it could definitely be done cheaper there is no doubt about that this build wasn't about trying to save money as such in that way was more so just buy top of the range stuff and see what it does and atleast with this turbo I have plenty head room to make more in the future
 
Hey, I'm currently working on very similar setup. My turbo is G25 660 0.72ar. The guy who's building my engine and Torque Developements tuner says this turbo is too big for SR20 and will be sluggish on the road. I would be very interested to see your dyno sheet at what rpm your turbo with larger ar makes boost and power. Any chance you have some videos as well? Instagram or facebook? Would love to see how it works as I still have time to change my setup.
 
Julius PS13 said:
Hey, I'm currently working on very similar setup. My turbo is G25 660 0.72ar. The guy who's building my engine and Torque Developements tuner says this turbo is too big for SR20 and will be sluggish on the road. I would be very interested to see your dyno sheet at what rpm your turbo with larger ar makes boost and power. Any chance you have some videos as well? Instagram or facebook? Would love to see how it works as I still have time to change my setup.
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Hey dude yeah I'll post my dyno sheet my instagram is kieranireland16 I only have a few videos of the car on the dyno as unfortunately the car was rear ended on a motorway and put into a wall I'd say the 0.72 housing will probably be the best all rounder still responsive and make good power mine is maybe slightly slower in response but is by no means bad and we were also having problems with the boost solenoid which is why the graph is a bit dodgy at the top end I have a new car coming from Japan that I'll be putting my engine and everything in but that won't be done probably till next year as you can see from the graph it starts climbing at 3500 to about 5000/6000 and if the boost solenoid wasn't toast would have been holding power till red line car was very drivable though and didn't try to blow the tyres off it also just wanted to make power it was sitting at around 400hp at the hubs but was dialled back just for a bit of safety if you want to have a chat about it at all probably best messaging me on instagram

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So an update I didn't want to have to make but unfortunately the car was rear ended and put into a wall whilst driving at 40mph on a motorway gutted to say the least but on the plus side I have a new car coming from Japan which is going to be getting my running gear swapped in thanks to the people who have shown an interest in my build i might start a new build thread when the new car a arrives but if anyone is interested in it probably be best to follow me on Instagram @kieranireland16
 
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