GT35R-equivelent, but bolt-on direct swap...heard of it?

[Rice Over Wheat]

When I was having my licp fabbed yesterday, there was a guy at the shop with a 550+whp Starion on a GT40. He said he decided against bb because he was worried about durability and/or reliability issues he'd read about. The guy doing my welding has a Nova in the high 10s all motor and carburated and he was saying the same thing, that there's more chance for something to go wrong and when/if it does it's far more expensive to rebuild. Is that true?

 

[Coup D E'Tat]

To my knowledge, BB cartidges cannot be rebuilt.

 

[Slippi84]

To my knowledge, BB cartidges cannot be rebuilt.

Yep this is the catch with ball bearing center sections they can not be rebuilt. There are however this new type of turbo I read about in this months Modified mag from IPT that are suposedly rebuildable but other than that ball bearing center scetions are not rebuildable thus makin a blown gt35r a sexy paperweight. This is unless your willing to pay 7-800 bucs for a new center section and then replace it

 

[clipsit]

ball bearing center scetions are not rebuildable thus makin a blown gt35r a sexy paperweight.

...I can do sexy paperweight...

 

[Caithness]

You have read wrong my friend. Dual ball bearing center section increases spool by 20% give or take. Less than 100rpms is def false. I do agree it's less than the 20% that is suposed to be in bigger turbos like the gt35r and gt3561 but you are still lookin at a 200prm diffrence and yes the transient response is more the kicker and if that should def not be overlooked. I personaly own a duall ball bearing turbo around the size of the turbos we're talkin about.

You know, I've spent several hours over the last few days searching multiple sources- google, here, supraforums, turbomustangs, evom, and other places you'd think you could find a definitive answer on ball bearing turbos and their effect on spool, and I've found exactly nothing to conclusively prove anything. At this point I would need a direct comparison with map sensor logs by a reputable shop taking the exact same car and switching out only the turbo. Something like a GT35R and a GT3561 would be perfect- they have to be the exact same wheels, exact same housings on compressor and turbine sides, only difference being ball bearing center or journal bearing. Tuning- they'd have to maintain identical AFR and timing. Test conditions- starting from the exact same rpm, same gear, same weather conditions, etc.

Without something like that I'm going to have to retract my previous statement and not say anything about ball bearing turbos and spool, because smart people have said directly conflicting things about the subject and while I've driven ball-bearing turbo cars, I've never owned one. Some people say ball bearing turbos do not spool any faster than their identically spec'd journal bearing counterparts, some say they spool at a much lower RPM, as much as 20 percent, 500 rpm, what have you. They provide varying degrees of evidence to support these statements but not one has provided the kind of test results I think would be needed to put an end to speculation.

 

[Slippi84]

You know, I've spent several hours over the last few days searching multiple sources- google, here, supraforums, turbomustangs, evom, and other places you'd think you could find a definitive answer on ball bearing turbos and their effect on spool, and I've found exactly nothing to conclusively prove anything. At this point I would need a direct comparison with map sensor logs by a reputable shop taking the exact same car and switching out only the turbo. Something like a GT35R and a GT3561 would be perfect- they have to be the exact same wheels, exact same housings on compressor and turbine sides, only difference being ball bearing center or journal bearing. Tuning- they'd have to maintain identical AFR and timing. Test conditions- starting from the exact same rpm, same gear, same weather conditions, etc.

Without something like that I'm going to have to retract my previous statement and not say anything about ball bearing turbos and spool, because smart people have said directly conflicting things about the subject and while I've driven ball-bearing turbo cars, I've never owned one. Some people say ball bearing turbos do not spool any faster than their identically spec'd journal bearing counterparts, some say they spool at a much lower RPM, as much as 20 percent, 500 rpm, what have you. They provide varying degrees of evidence to support these statements but not one has provided the kind of test results I think would be needed to put an end to speculation.

I agree to bad no shop would actualy go threw that so we could all know 100% how much diffrent it is over the journal bearing. I will tell you that I have seen first hand how much better transient response is. Spool I have never gone from the same turbo to another just ball bearing so I can't talk as that's the only way to compare but I will tell you that having driven in a gt35r car which had previously had a journal bearing 60-1 the transient response was A LOT better in the gt35r. I know your like these turbos are the same and that's the point. The 60-1 being smaller and having the same to4s cover should have kicked right back into action after switching gears but it had noticable lag between pulling like a raped ape again as aposed to the gt35r which just pulled and pulled and pulled even after shifting as if it never shifted at all. just my .02

 

[GVR4592]

I changed my journal bearing CHRA for a ball bearing CHRA. Full boost comes on about 300 rpms sooner depending on the gear, and boost response between shifts is a little better. The turbo is a PTE SCM4431.

 

[Kevin Jewer]

Too many blanket statements in this thread. The one I will pick on for know is the NLTS being worth 2 tenths in the quarter. There are many variables that come into play with this. On a small turbo like a 14b or 16g 2 tenths isn't too far off. But on much larger and much laggier turbos it can be worth MUCH more. On the T67, despite being on a stroker, NLTSing the 3-4 was worth 3-4 mph (no change in ET), and NLTSing the 1-2 and 3-4 was worth nearly a full second. It might be slightly less for someone that shifts faster than I do. Too many variables.

Same for the boost threshold and lag gains from BB centers. I've seen two nearly identical turbo with the 35R compressor wheel have the same exact boost threshold. The turbos were not identical however. The larger the turbo is, the less the gain is going to be. The journal bearing can be a relatively small hindrance compared to the huge inertia of the two wheels, making the gain much smaller than you would get on smaller turbos. In my opinion the biggest benefit is the lack of a thrust bearing for me to destroy when running the turbo at its maximum capacity.

 

[Slippi84]

Too many blanket statements in this thread. The one I will pick on for know is the NLTS being worth 2 tenths in the quarter. There are many variables that come into play with this. On a small turbo like a 14b or 16g 2 tenths isn't too far off. But on much larger and much laggier turbos it can be worth MUCH more. On the T67, despite being on a stroker, NLTSing the 3-4 was worth 3-4 mph (no change in ET), and NLTSing the 1-2 and 3-4 was worth nearly a full second. It might be slightly less for someone that shifts faster than I do. Too many variables.

Same for the boost threshold and lag gains from BB centers. I've seen two nearly identical turbo with the 35R compressor wheel have the same exact boost threshold. The turbos were not identical however. The larger the turbo is, the less the gain is going to be. The journal bearing can be a relatively small hindrance compared to the huge inertia of the two wheels, making the gain much smaller than you would get on smaller turbos. In my opinion the biggest benefit is the lack of a thrust bearing for me to destroy when running the turbo at its maximum capacity.

Your not seeing the forrest threw the trees though man the point isn't to debate how much faster you go using NLTS it's just to give people who aren't so familiar with ball bearing vs non ball bearing center section spool and transient response. If you read what I wrote and understand that NLTS takes away the delay in boost response after shifting annd that that affect is similar to ball bearing center section effect on a turbo vs a non ball bearing turbo then you got the point and the only point. Anything else you want to conclude from what I said is looking to deep into the analogy.

 

[Kevin Jewer]

Whatever your point was, which admittedly can be tough to decipher given all the grammatical errors , people will read things like this and think that NLTS is always worth 2 tenths. I don't like blanket statements given without some kind of qualifier or disclaimer, that's all. I wasn't trying to argue with you, simply trying to add the rest of the missing information for the other people who are reading this now or may find it in future searches.

 

[Slippi84]

Whatever your point was, which admittedly can be tough to decipher given all the grammatical errors , people will read things like this and think that NLTS is always worth 2 tenths. I don't like blanket statements given without some kind of qualifier or disclaimer, that's all. I wasn't trying to argue with you, simply trying to add the rest of the missing information for the other people who are reading this now or may find it in future searches.

In that case for the simple minded in a nut shell ball bearing turbo equals less waiting for boost. gt3r more money less waiting gt3561 less money more waiting. Simple enough ?