SR20 wastegate issues creep/overboost.

[XxOLIVERxX]

Hey guys I'm new to zilvia but been in the Silvia game for a few years now.
Got a question I'm hoping someone can help me with.

Iv recently installed a new td05 18g turbo, tial 38mm external gate and a stock manifold modified very well to accept the ext gate right above the turbo inlet in the rear housing. The area is very well welded and smoothed out appears like it wouldn't cause any issues. The first wastegate I was using had a "8psi spring" was holding boost at about 5.5/6psi fine for a while and then one day it jammed open. Since then I disasembled the gate and unstuck the valve. Worked fine for another 40 minutes or so and then it jammed open again.

Called it quits and bought a Godspeed type rs wastegate (copy of turbosmart ultragate 38) this one apparently has a 5 psi spring in it but starts creeping open at about 2.5-3 psi sometimes! Mostly sits around 10 psi And then at around 5500 rpm jumps to almost 12 till redline.

Now I'm currently running this setup untuned on a mostly stock s15 engine with bolt ons while saving for a nistune ecu. The aim was to run the car at around 8 psi (max of 10) so not to damage anything in the meantime. And obviously boosting up to 12 psi is probably abit dangerous. The car is also very laggy because the gate is opening so early wasting boost pressure and making it sound like a tractor with little throttle applied.

Now the way I understand it I'm experiencing wastegate/boost creep. But will replacing the spring with a new brand name spring to suit this gate solve the issue? Because I think that would stop it opening so early but I dunno about the over boosting side of the problem.. Not sure what to try next. The gate is hooked up directly from the fpr/boost gauge line. It was connected to the intercooler pipe in front of the rb before as per install instructions and running to the lower port with top port open.

If anyone has the answer if love to hear it! Cheers for reading👍

[Fuego]

Godspeed isn't best known for their moving parts honestly. Do you have an EBC with it?

[XxOLIVERxX]

Nope no ebc connected just running straight from the vaccuum source

[OnTheChip]

NismotronicSA (http://www.nismotronic.com/product_info.php?cPath=22&products_id=29) includes programmable boost control with high/low boost settings and boost-by-gear. If you go nistune you'll need a separate boost controller.

[Kingtal0n]

Hey guys I'm new to zilvia but been in the Silvia game for a few years now.
Got a question I'm hoping someone can help me with.

Iv recently installed a new td05 18g turbo, tial 38mm external gate and a stock manifold modified very well to accept the ext gate right above the turbo inlet in the rear housing. The area is very well welded and smoothed out appears like it wouldn't cause any issues. The first wastegate I was using had a "8psi spring" was holding boost at about 5.5/6psi fine for a while and then one day it jammed open. Since then I disasembled the gate and unstuck the valve. Worked fine for another 40 minutes or so and then it jammed open again.

Called it quits and bought a Godspeed type rs wastegate (copy of turbosmart ultragate 38) this one apparently has a 5 psi spring in it but starts creeping open at about 2.5-3 psi sometimes! Mostly sits around 10 psi And then at around 5500 rpm jumps to almost 12 till redline.

Now I'm currently running this setup untuned on a mostly stock s15 engine with bolt ons while saving for a nistune ecu. The aim was to run the car at around 8 psi (max of 10) so not to damage anything in the meantime. And obviously boosting up to 12 psi is probably abit dangerous. The car is also very laggy because the gate is opening so early wasting boost pressure and making it sound like a tractor with little throttle applied.

If anyone has the answer if love to hear it! Cheers for reading

why would you go through all this trouble when the stock s15 sr20det can and will handle 12psi easily with all oem components? Did you mean you have an sr20DE engine and converted it to turbo?
If so nothing will save you, the compression is too high. I would convert it back to stock, sell it, and get a DET engine.
And if you DO have the DET, then go back to the stock turbo, stock manifold, etc.. and just set it to 7-12 psi and forget about it.

[XxOLIVERxX]

Stock turbo is fucked hence upgrade. The plan was to run wastegate pressure untill iv saved up enough coin for a nistune.

[Kingtal0n]

why not replace the stock turbo. save you alot of headache and money tinkering around all day with this cheap aftermarket bull$#!T. Spools faster. No need ECU. OEM parts ftw.

[XxOLIVERxX]

Because I want more power. I drift the car and stock t28 on 14 psi plus poncams isn't enough for barbagallo. It's a long track and need the power to push though it

[Kingtal0n]

Because I want more power. I drift the car and stock t28 on 14 psi plus poncams isn't enough for barbagallo. It's a long track and need the power to push though it

You cant have more power without larger injectors. Doesnt matter what turbo you choose. And you cant have larger injectors without a tune.
You are paying for bigger injectors + a tune + a larger maf sensor + turbocharger + wastegate + plumbing.... thousands of dollars and headache all for about 60-80 extra horsepower. Reality is cruel.

IMO spray a progressive 50 shot of nitrous instead. $300 done. If you really want the larger turbo to work out you need to use high quality parts.

[XxOLIVERxX]

Thanks for you input but it doesn't answer my question.

Stock 440cc is fine for 300 hp on pump 98 even more on p100. Anything over 300 I'm happy.

Il be running 17-18 psi z32 Afm nistune etc mate made 315hp at the wheels with the exact same setup.

[Kingtal0n]

Thanks for you input but it doesn't answer my question.

Stock 440cc is fine for 300 hp on pump 98 even more on p100. Anything over 300 I'm happy.

Il be running 17-18 psi z32 Afm nistune etc mate made 315hp at the wheels with the exact same setup.

every dyno is different, mate. My dynojet says 440cc injectors with a 12:1 air fuel ratio are 95% duty cycle after 295RWHP, which is more like 330bhp.

But the neighbor's dyno says the same car only makes 255rwhp. Hmm.

On the other hand, I can keep raising boost and make more power, leaning out the air fuel ratio. We can make 350RWHP with 440's with a 13.3:1 air fuel ratio, sure thing. It still "works" its just not safe. And if you want to be in the 11's you can't make 300 with 440cc injectors, without raising the fuel pressure. Power isn't everything.

Trap times dont lie. What does it trap? Ah, you probably don't care.
one thing I dont understand is why you wouldn't install larger injectors if changing the ECU anyways.

[XxOLIVERxX]

Because I want to make the best out of what I have so I can actually get out and drive the car! It's not a garage ornament I drive it most days and it gets driven hard. Il just take it to the tuner and get what it makes and il be fine for awhile untill I can afford/feel the need to upgrade more shit. In struggling to afford the stuff I need right now without changing shit I don't have to right now

Now Iv justified myself can you help me with my wastegate problem? Cheers.

[Kingtal0n]

Because I want to make the best out of what I have so I can actually get out and drive the car! It's not a garage ornament I drive it most days and it gets driven hard. Il just take it to the tuner and get what it makes and il be fine for awhile untill I can afford/feel the need to upgrade more shit. In struggling to afford the stuff I need right now without changing shit I don't have to right now

Now Iv justified myself can you help me with my wastegate problem? Cheers.

gas is more important. Rule #1 with these motors is you need to fuel them. modifications mean nothing if you cannot provide the fuel to go with it. Your biggest and most pressing concern is the fact you have stock injectors and want a larger than stock turbocharger. There is no point in upgrading your computer if you arn't also upgrading your injectors- thats actually the whole point.

Want to fix wastegate? Buy a quality wastegate. maybe a nice Tial or something.

[XxOLIVERxX]

Like I said... I replaced the turbo because it crapped out and I wanted to prepare for future upgrades instead of doing everything twice.

Il tune the car to as much as it can be tuned safely. Which from what iv heard/seen at my tuners shop in wa on pump gas 98 octane it will make 300 on stock injectors. S15s have larger 440s instead of the normal 370cc.

If it doesn't make 300 I don't really care. Il save money for injectors and a retune later down the track.


Are you sure it's a wastegate problem? Iv dismantled the gate since op and smoothed out the shaft so it slides open and closed very nicely the diaphragm and everything inside looks to be perfect. Is it possible that this turbo is flowing so much air in the top end the gate is simply too small to let the pressure out? A friend suggested this but seems unlikely as compared to an internal gate 38mm should be plenty big enough I thought.

[Kingtal0n]

you said everything was fine until you changed the gate. If the only thing that changed is the gate, then why wouldnt you suspect the gate?

Its like changing your shirt from purple to yellow, and then asking if your hair is causing you to look yellow instead of purple.

[XxOLIVERxX]

Okay I probably forgot to include this detail, iv now fixed the original gate.. Smoothed the shaft out and now it's sliding in and out very nicely. ;) Not tight and notchy like it was before. Reinstalled it and the gate is opening at spring pressure (8psi) and stays there untill very high revs around 6k upwards and then spikes up to 12 and stays there till you hit limiter exact same as how the other gate was acting.

To me it seems like the turbo and cams are flowing too much air and the wastegate can't dump that much pressure to keep it at 8 psi. Turbo is obviously meant to be run at much higher pressure than this anyway.