another gt2871r too much uncontrollable boost

[bl3ujay07]

Alright, so i just finished my set up not too long ago, gt2871r (disco potato style), denso 550cc, z32 maf, power fc and pfc boost control kit, sr20det if it matters.

What is happening, is too much uncontrollable boost from turbo. I just bought a brand new stock adjustable wastegate, the 12-14 psi actuator i believe. First off, running off the pfc boost controll kit, im gettng fuel cut everytime i punch the gas pedal. I've tried setting it from .7-1.0 bar(???) and adjust the duty cycle, even when setting the value to 20 (the lowest value), it is still over boosting.

Today, turned off the boost control from the comander to try and run off the wastegate to see if it would hold a steady boost pressure. Did a 3rd gear run, and the low and behold, still over boosting, hitting 1.2 bar (reading from pfc commander) and i let go.

Can someone help me out here? Im leaning towards the actuator, but it was brand new. Changed out new line from actuator and such and still same thing.

My set up for the boost controller kit:
Boost Valve
COM --> actuator
NO--> vac source, teed with bov to nipple on tb

Map Sensor-->filter-->fpr vac source

[jspaeth]

Everything looks okay.

Did you PRELOAD the wastegate spring? You need to check how far the arm extends while there is no pressure....with the car off obviously.

The arm should BARELY slide onto the wasegate actuator arm so that there is little/no preload.


Try running vacuum line directly from hotpipe to wastegate also, see what that does.

[Sileighty_85]

you really need 740CC inj for the 2871R.

Waste gate preload settings arent that big of a deal since you can control the gain on the PFC and the PFC will pretty much adjust itself for set boost.

But if the W/G is too tight it will be a problem

Mines on there prety tight and using the supplied W/G and its dead on for me and holding 21+ PSI

[Burglervr6]

you don't need 740s......wtf on a 2871? What happens if he decides to go top mount 30R or 35R 810s-1000s? 550ccs are plenty. And you might not be hitting fuel cut, are you still running the rubber intake tubing? Post a pic of your set up.

[Sileighty_85]

Originally Posted by Burglervr6

you don't need 740s......wtf on a 2871? What happens if he decides to go top mount 30R or 35R 810s-1000s? 550ccs are plenty. And you might not be hitting fuel cut, are you still running the rubber intake tubing? Post a pic of your set up.

are you smokeing crack?

Dude 550's are good for like 300ish on pump gas
740's are good for 400

The GT2871R depending on trim makes about 400

I have the 2871R with 740cc injectors, injector duty cycle is around 70% making 363whp at 21PSI

Now if you keep it around 14-16psi he'll be fine then.
I always say "its better to have too much fuel then not enough"

[jspaeth]

Originally Posted by Sileighty_85

are you smokeing crack?

Dude 550's are good for like 300ish on pump gas
740's are good for 400

The GT2871R depending on trim makes about 400

I have the 2871R with 740cc injectors, injector duty cycle is around 70% making 363whp at 21PSI

Now if you keep it around 14-16psi he'll be fine then.
I always say "its better to have too much fuel then not enough"

Yes, this is correct. For getting GOOD power out of 2871R, 550s are too small.

Also, what I was saying, is temporarily ignore boost control, run off stock wastegate.

If he is getting more than 12 psi with just wastegate, than something's not right.

[bl3ujay07]

I made the mistake of thinking 550cc would be enough. Should have bought 740cc he first time around instead but ill stick with the 550cc for now.

I tried running just off the wastegate, and it is more thn 12 psi, it shows i hit 1.2kg on the power fc running on just the actuator. The actuator is brand new. Ill try and take off the wastegate and make it long as possible. The 10-12 psi rod however, is kind of short and needs some pressure to be able to mount it. This is why im thinking its the wastegate.

[jspaeth]

Originally Posted by bl3ujay07

I made the mistake of thinking 550cc would be enough. Should have bought 740cc he first time around instead but ill stick with the 550cc for now.

I tried running just off the wastegate, and it is more thn 12 psi, it shows i hit 1.2kg on the power fc running on just the actuator. The actuator is brand new. Ill try and take off the wastegate and make it long as possible. The 10-12 psi rod however, is kind of short and needs some pressure to be able to mount it. This is why im thinking its the wastegate.

You don't want it "long as possible"

That implies that under no boost, the wastegate is OPEN.

Make it JUST short enough that it requires the tiniest bit of force to get it over the rod that it hooks onto.

If you do this, and run vacuum line from hotpipe to wastegate and see more than 12-14 psi MAX, then something is up with that wastegate acutator.

[bl3ujay07]

^^^I'll try it out probabl tomorrow. when i say long as possible, i mean long as possible, but i will still be hard trying to hook it onto the flapper. It's pretty short. Ill update it tomorrow.

[S13 curtis]

Originally Posted by Sileighty_85

are you smokeing crack?

Dude 550's are good for like 300ish on pump gas
740's are good for 400

The GT2871R depending on trim makes about 400

I have the 2871R with 740cc injectors, injector duty cycle is around 70% making 363whp at 21PSI

Now if you keep it around 14-16psi he'll be fine then.
I always say "its better to have too much fuel then not enough"

Not to be an ass hole but 550cc are fine for pump gas and a 2871, Drifterprotogy85 ran 740cc injectors and he was making 502whp on pump gas. hell i run E-85 and i hit in the 90%'s after 17psi with the stock FPR ,740cc, and 2871r so he is fine with 550's. you guys need to stop giving bad info.

[bl3ujay07]

^^^trust me, 550cc is not enough. I did a test run and it was pretty damn close to 90% duty cycle, which is not good at all. You are hitting 90% duty cycle on your 740cc at 17 psi?

Ok, i lengthen the actuator rod, ran the car with just the actutor (and the map sensor still connected to read boost level) and it was at 1.0+ kg/cm, the most it spiked to was 1.11 kg/cm. Thought, ok if i plug in the boost controller, should regulate it better. Turned boost to 1.0kg/cm and changed duty cycle to 36 and still boost spiked to like 1.3. Was able to take rpm further but still hit boost cut. Will try and lower duty cycle more on lower boost setting for safe side.

[S13 curtis]

Originally Posted by bl3ujay07

^^^trust me, 550cc is not enough. I did a test run and it was pretty damn close to 90% duty cycle, which is not good at all. You are hitting 90% duty cycle on your 740cc at 17 psi?

Ok, i lengthen the actuator rod, ran the car with just the actutor (and the map sensor still connected to read boost level) and it was at 1.0+ kg/cm, the most it spiked to was 1.11 kg/cm. Thought, ok if i plug in the boost controller, should regulate it better. Turned boost to 1.0kg/cm and changed duty cycle to 36 and still boost spiked to like 1.3. Was able to take rpm further but still hit boost cut. Will try and lower duty cycle more on lower boost setting for safe side.

yea, before i took off the 2871 and put on an s15 t28. the 2871 is goin back on but i got a lil better plans for it.
i run E-85 its like close to 40%more fuel needed.

[garagelu]

I had nismo 555cc injectors on my 2871r for a while making 379hp on a dynapac. And yes this was at stock fuel pressure but close to maxing them out but still safe. 379hp would probably equate to 350-360 so on a dynojet....im guessing.

550cc should be fine up to 350hp. If you are running out of fuel, they may not be true 550cc or may have some other problems in your fuel system.

I run 740cc injectors now because I am making a little more power on my 2871r setup.

[fliprayzin240sx]

DID YOU BORE OUT THE WASTEGATE FLAPPER HOLE?!?! First thing I do with any Garrett internal wasted turbo...bore out the flapper hole with a dremmel to almost match the flapper size. 99% of the time you boost spike is due to that shit...

[jspaeth]

So you lengthened the rod, and now with just the wastegate actuator, you hit like 14 psi or so.

Good.

Now lengthen it some more!

You should have to exert little/no effort to get the end of the rod over the peg that sticks out.

If you are having to "pull" on the rod to get it to slide onto the peg AT ALL, then you are still preloading the wastegate, and you will never see the 12 psi max that the wastegate is rated for.

Try setting all of the duties as low as they can go and doing some pulls and seeing what happens.

What kind of boost controller again?

[bl3ujay07]

i extended the wastegate as far as possible already, probably five or six thread holding on to each other, and i still have to force it to connect actuator to flapper. Any less, and i dont know how reliable it will be just running on four or five threads.

I have the apexi boost control kit for the power fc. I will try and run on lowest boost setting and drop the duty cycle to 20 (which i believe is the lowest value). Will try and do some test runs tomorrow.

As for the flapper, can more people chime in on it? How many people running the gt2871r actually port their flapper hole? I would rather not try and "modify" a turbo if i dont have too.

[bl3ujay07]

another question, can you fight knock with higher octane rating? Im running91 atm, but if going higher octane will help, ill start gasing half 100 and half 91 just in case i need it.

[jspaeth]

Originally Posted by bl3ujay07

another question, can you fight knock with higher octane rating? Im running91 atm, but if going higher octane will help, ill start gasing half 100 and half 91 just in case i need it.

Bang your issue solved.

The reason you are overboosting is bc your wastegate is preloaded. Period.

You can not "underboost".

So if you have a 12-14 psi wastegate preloaded, you are ABSOLUTELY going to hit like 17 psi or so, which is what your boost controller is reading.

The boost controller cannot make it boost less than that, you are asking it to do something it can't do.

Boost controller can only make boost higher than what the wastegate would do on its own.

[bl3ujay07]

someone shoot me...so will i be able to boost 12-14 reliably if i bought one that is preloaded at like 6-8, the other actuator?

[fliprayzin240sx]

You can try but I'm still willing to bet that when it hits the boost that the flapper opens up, itll continue to build boost due to the restrictive size of the flapper opening. That was the only way I could keep my boost controllable. I had an HKS wastegate on both a GT2871R and a GT3071R. They both had the boosting issue untill I bored out the flapper hole.

[bl3ujay07]

flipratzin240sx, did you just dremel the hole?

[garagelu]

Originally Posted by fliprayzin240sx

DID YOU BORE OUT THE WASTEGATE FLAPPER HOLE?!?! First thing I do with any Garrett internal wasted turbo...bore out the flapper hole with a dremmel to almost match the flapper size. 99% of the time you boost spike is due to that shit...

Oh yea I totally forgot about this. Yes! I had the same problem. When I was on the dyno, I kept getting slight boost creep problems. I took a dremel to bore and smooth the hole out. Just make sure you don't go to crazy with it. Check the surface area of the flapper and bore out according to it.

Now my boost problems are pretty much gone. If it does creep, its on a cold day and only about 1 psi or so.

And people, you can only preload that arm so much till you don't have enough arm strength to get the arm onto the flapper arm. I seriously doubt thats his problem. I tried adjusting my arm when I had boost creep problems and it never helped.

[jspaeth]

Originally Posted by garagelu

Oh yea I totally forgot about this. Yes! I had the same problem. When I was on the dyno, I kept getting slight boost creep problems. I took a dremel to bore and smooth the hole out. Just make sure you don't go to crazy with it. Check the surface area of the flapper and bore out according to it.

Now my boost problems are pretty much gone. If it does creep, its on a cold day and only about 1 psi or so.

And people, you can only preload that arm so much till you don't have enough arm strength to get the arm onto the flapper arm. I seriously doubt thats his problem. I tried adjusting my arm when I had boost creep problems and it never helped.

Ugh what is everyone not getting.

He has a 12-14 psi wastegate arm.

He has it preloaded.

And he is wondering why his boost is hitting like 20 psi.


Because it's preloaded!!!!!!!!!!!!!!!!!

[ashtonroche]

Originally Posted by garagelu

I had nismo 555cc injectors on my 2871r for a while making 379hp on a dynapac. And yes this was at stock fuel pressure but close to maxing them out but still safe. 379hp would probably equate to 350-360 so on a dynojet....im guessing.

550cc should be fine up to 350hp. If you are running out of fuel, they may not be true 550cc or may have some other problems in your fuel system.

I run 740cc injectors now because I am making a little more power on my 2871r setup.

550's are good to right at about 360-370whp, 740's are good to around 540whp, Im running 740's on my setup and made 461whp,391wtq and i was not even close to maxing them, Not to mention at 4 bar fuel pressure they are good to over 600+. Once i go back to the dyno with the new custom intake mani with Q45 throttle body and 28psi ill have my fuel pressure between 3-4 bar and should be perfect. 550whp all day long at that level.

[jspaeth]

This thread needs to be closed. I reread the original post, and this is absurd.

Originally Posted by bl3ujay07

Alright, so i just finished my set up not too long ago, gt2871r (disco potato style), denso 550cc, z32 maf, power fc and pfc boost control kit, sr20det if it matters.

What is happening, is too much uncontrollable boost from turbo. I just bought a brand new stock adjustable wastegate, the 12-14 psi actuator i believe. First off, running off the pfc boost controll kit, im gettng fuel cut everytime i punch the gas pedal. I've tried setting it from .7-1.0 bar(???) and adjust the duty cycle, even when setting the value to 20 (the lowest value), it is still over boosting.

Today, turned off the boost control from the comander to try and run off the wastegate to see if it would hold a steady boost pressure. Did a 3rd gear run, and the low and behold, still over boosting, hitting 1.2 bar (reading from pfc commander) and i let go.

Can someone help me out here? Im leaning towards the actuator, but it was brand new. Changed out new line from actuator and such and still same thing.

My set up for the boost controller kit:
Boost Valve
COM --> actuator
NO--> vac source, teed with bov to nipple on tb

Map Sensor-->filter-->fpr vac source

You CANNOT get a 12-14 psi wastegate spring to hold 0.7 bar.

Also, he already confirmed that he IS having to pull on the actuator rod to get it onto the wastegate arm (PRELOAD).


There is no way that a preloaded 12-14 psi wastegate actuator is going to give anything less than 16 psi or so.....which explains why he is "overboosting" to 1.2 bar....EXACTLY where it should be.

/thread

[Sileighty_85]

Originally Posted by jspaeth

This thread needs to be closed. I reread the original post, and this is absurd.





You CANNOT get a 12-14 psi wastegate spring to hold 0.7 bar.

Also, he already confirmed that he IS having to pull on the actuator rod to get it onto the wastegate arm (PRELOAD).


There is no way that a preloaded 12-14 psi wastegate actuator is going to give anything less than 16 psi or so.....which explains why he is "overboosting" to 1.2 bar....EXACTLY where it should be.

/thread

hahaha good catch.

Not entirely true, I have the 3 in inlet version, i fabed up a W/G actuator bracket so that the actuator rod wouldnt bind from the angle but i was able to lessen the preload on the Flapper and lowered mine to about .8 IIRC

So you'd just have to lessen the preload to lower the boost by moving the Actuator closer ot the flapper valve
but you can only move it a little bit.

But like jspaeth said at its current configuration you cannot lower the boost anymore

[bl3ujay07]

^^^You have a picture of your fabbed actuator bracket? How much are you willing to sell it for?

[Fre3_World313]

So I want to do away with my manual boost controller.

Can someone tell me which vacuum hose from throttle body goes to wastegate?

Still running 25lbs on a t28

I’m one pull away from pushing a head gasket..

I want to make the psi. At a sock setting.

So I don’t have to let off the throttle in fear of blowing it up.

Thanks

[brndck]

Originally Posted by Fre3_World313

So I want to do away with my manual boost controller.

Can someone tell me which vacuum hose from throttle body goes to wastegate?

Still running 25lbs on a t28

I’m one pull away from pushing a head gasket..

I want to make the psi. At a sock setting.

So I don’t have to let off the throttle in fear of blowing it up.

Thanks

you still haven't figured a damn thing out. this thread is from 2009. why the fuck are you posting in here to contribute NOTHING???
why the FUCK are you running 25psi on a t28???
does google not exist in iowa???
no wonder you're so far in the red.

[Fre3_World313]

Actually I fixed the running rich problem.

Been driving it all around.

Just got enough respect for my motor, to keep my damn foot outta it.

Either help me keep from pushing my head gasket. Or just keep being dick.

Think Ik know what you’ll do lol