Gt4276 Wow

[Eticket]

After waiting almost 3 months, my fabricator and I finally installed a GT4276 non ball bearing on my car yesterday/last night.

Took some time to build a substantial bracket to help support the turbo and then, to refabricate a downpipe.

Since it was 6am when we got done, I only took the car for a short blast down the street.

My car now feels amazingly different from when I had the 76GTQ. Seems to spool faster AND make more power!

I still have to fix some intercooler piping issues and make a turbo inlet hose setup, but can't wait to get it to the track.

Anyone else have this first impression? I'm quite amazed. Exhaust also is louder and sounds more raspy.

 

[Louie L.]

I was amazed on how quick the non ball bearing unit with a 1.01 housing spooled. I was able to use my old TSM ATI converter and it did quite well.

 

[Eticket]

After researching everything all of you have done, I went with the 1.15 housing. Haven't footbraked it yet to see what it'll do at the line. I have no doubt I'll have to add fuel across the board.

My car was for sale for some time, but so long as I get a job relatively soon upon graduation (MBA), I think I'll keep it now and see how fast it will really go.

 

[norbs]

That is on a 270 ci motor correct, not a 231?

 

[Eticket]

Yes.

 

[Eticket]

Took the car out for a test drive this weekend and found that the boost will not go down from 18psi at all. Without double checking everything yet, do you think that maybe my knock-off hks 50mm gate doesn't flow enough air? When I had it apart last, I did notice that the valve doesn't actually move that much.

It controlled boost just fine with the 3 bolt 76gtq, but I wonder if now the exhaust "likes" to go through the turbine housing instead of the wastegate. That maybe I need to make sure the gate actually flows enough?

I can definitely hear the wastegate opening as I have it dumped for the time being... Just can't figure out why it doesn't "waste" enough exhaust.

ps.. it has a very light, maybe 4psi spring in it.

John

 

[lazaris]

John,

A 50mm gate should be able to handle the flow, however maybe not for 4 psi. Its possible the valve is sticking and not opening all the way to by-pass enough exh. The gate has to flow the most at lower boost to by-pass enough exh to maintain that low boost setting. Is it running on just gate pressure now? Or is the top of the gate seeing any compressor flow keeping the valve shut?

 

[Eticket]

Laz,

I checked.. the gate was not stuck at all. I have had it rust up on me before.

As far as boost to the top, yes.. It sees it, but I would guess in this case not, because the innovative controller shouldn't be opening the solenoid to let the top see boost.

Nothing else had changed except for that I have a different turbo and the wastegated dumped instead of back into the header.

With the old turbo, I was pretty able to set the boost as low as I wanted.. especially with a light spring. I was having to run a really heavy spring to get the boost over 22psi..

I was just thinking the exhaust back pressure/dynamics must be totally different with this turbo.

 

[lazaris]

Well if exh BP was too high it will then work to force the valve to open, by-passing more exh flow which would work to lower the boost pressure. Obviously if nothing else has changed besides the turbo then it could be possible you do not have enough gate, but a 50mm valve is quite large.
I would make sure there is no pressure seeing the top of the gate. Is it possible your controller is malfunctioning? Maybe you could dis-connect the hose feeding the top of the gate to be sure. Double check inside the gate too. Make sure the valve has full travel.

 

[DR BOOST]

it is possible that the gate needs to be cleaned of carbon on the stem of the valve. it may have only needed to open a certain amount with your old turbo, and the carbon on the stem is now preventing it from opening more.

hth

surej

 

[HighPSI]

John,
Check your wastgate and hoses. I was able to take the boost down to 4-5 lbs with a TIAL 44 and that turbo. Just for the heck of it, I would remove the top wastegate hose and test it.

 

[Eticket]

Guys.. thanks for your input.. I will remove the top hose to see what happens. Other than that, I took the gate apart 100% and cleaned it.. antiseized the shaft.. etc.. since the car has been sitting for a couple of months.

I probably should mention that I do have a very light wastegate spring in it too. Maybe I should check the vacuum going to the boost controller.. I haven't looked down at it to see what it is reading.

Can't wait to get it to the track, but I am limited by injectors still.

Is there any problem with the 95lb disc style locking up a high fuel pressure... Kind of like the MSD 50's do?

Cal, is there any way to get you to Oklahoma this year?