T28 ball bearing turbo to T28 journal bearing

[TAP240]

Would it effect my tune negatively if I downgrade from a T28 ball bearing turbo to a T28 journal bearing turbo? I'm sure I'll see some power loss, but will it effect my tune to the point where I'll need a re-tune, or will it just be a matter of the car running slightly richer (meaning a difference in .1-.3 a/f compared to the current tune). Some insight in this situation will be greatly appreciated!

**edit: If I go to a journal bearing turbo, but add a tubular manifold, could that be comparable to a ball bearing turbo with the stock manifold? (Kind of hard to make sense of my question, but I think the principle is implied in there lol)

Thanks

[waste_of_space]

To me the journal bearing t28 was an UPGRADE to the 14 bb t28, since it has the larger .86 A/R exhaust housing.

It shouldn't make a huge difference on your tune, and you'll be able to squeeze a little more power out of your car with the larger exhaust (and the fact that you can run a little more boost)

[TAP240]

To me the journal bearing t28 was an UPGRADE to the 14 bb t28, since it has the larger .86 A/R exhaust housing.

It shouldn't make a huge difference on your tune, and you'll be able to squeeze a little more power out of your car with the larger exhaust (and the fact that you can run a little more boost)

So it will have a beneficial effect, running the t28 journal bearing with the tubular manifold, as opposed to the t28 ball bearing with stock manifold? Will running the journal bearing with the tubular manifold effect my tune much? The car was tuned with the ball bearing t28 with the stock manifold...

[waste_of_space]

I doubt it'll have any significant impact on your tune, as the turbos are, for the most part, similar.

One thing you should do though, is take your bb t28 compressor housing, and swap it with your gtir/journal bearing t28 compressor housing. Makes for slightly faster spool on the journal bearing turbo (which is still going to spool up quickly)

I ran a gtir turbo with 14 compressor housing on it and loved it, it's the best "stock" turbo setup you can run IMO.

[TAP240]

I doubt it'll have any significant impact on your tune, as the turbos are, for the most part, similar.

One thing you should do though, is take your bb t28 compressor housing, and swap it with your gtir/journal bearing t28 compressor housing. Makes for slightly faster spool on the journal bearing turbo (which is still going to spool up quickly)

I ran a gtir turbo with 14 compressor housing on it and loved it, it's the best "stock" turbo setup you can run IMO.

When you say slightly quicker spool, are you talking a difference between 100-200 rpm? Or more than that...

[Croustibat]

no diff on the tune, except a little downgrade on spool time if it was perfectly tuned.

dont change manifold, you will downgrade low and mid revs for maybe 2HP at the top. This is a turbo engine, remember ? It needs gas to be hot and fast. Tubby manifold have long, large runners, and thin wall, meaning gases will flow slower and lose a lot of heat before reaching the turbo. A T28 does not make enough flow to justify larger exhaust manifold runners. Unless you start running a gt2871r at higher boost, dont change your exhaust mani.

You may even get more power by upping boost a bit, as journal bearing T28 can take more flow than ball bearing.

Beware though, mounting wise, you will have to change the oil return "line" when switching from T28bb to T28 . Also, check if you have an oil restrictor on the oil intake line, if you do, remove it. It sometimes is integrated in the line, most of the time it is in the turbo though, but it is worth checking ... otherwise your turbo will die fast.