Turbo builds

[Nicholas1996]

Anyone running a 6870? I have some questions. Thinking about getting one but not sure.

[mleveroni]

Anyone running a 6870? I have some questions. Thinking about getting one but not sure.

Interested in feedback from anyone running a 6870 or 6766. Especially in terms of spool time compared to a 6266. Was thinking about stepping up the turbo eventually from a 6266 JB to maybe a 6766 BB and wanted to know how much it would change when boost came in. Originally went with the 6266jb for a few reasons. First being that the motor was stock and I didn't think anything more was necessary. Second, the clutch was stock so I figured a journal bearing would spool a bit later and be easier on the clutch. Third, it was pretty cheap for a new one. However, now the motor is currently being built and I got a twin disk clutch.

Here is my setup by the way:

Maximum PSI kit (intake manifold, intercooler, spa exhaust, etc)
Precision 6266JB
Tial WG
AEM Infinity
AEM boost controller
Flexfuel
Dual In-tank walbro 450's
8AN feed, 6AN return
Radium Rail
ID1050's
30 shot of nitrous (never actually used and probably wont. Had it and just threw it in to be ridiculous)
Motor (in the works, machined, new bearings, etc. Here are the highlights)
-CP 9.5:1 pistons (87.25mm)
-Carillo rods
-ARP L19 headstuds
-Supertech valve springs
DKM twin disk clutch

I didn't know things like pistons took 5 weeks, plus things are just out of stock from covid, so the motor is currently waiting at the machine shop. Once they have everything it should be quick, so I am hoping to have the car running by the end of August. I am happy with the 6266 and will run that for a bit, but with all this cash into the motor, I feel like it would be a waste not at least have a tune that steps it up a bit lol. It is worth noting that I have a map for E85 but mostly run pump 93. I can step up the boost on the new motor but on pump gas I wouldn't go crazy. So I am also wondering if the amount of boost it would take a 6766 to match the power of a 6266 at say 20psi would be significantly less or just negligible.


Eventually I am going to change the turbo to a ball bearing, but my question is if there is much of a benefit to a 6766BB or 6870 over the 6266BB or 6466BB which most people use.

On a side note, on stock motor on pump 93, I was running 12psi at most. The car had a base map that ran fine but was really just meant to be safe for the time being. Might have gone to maybe 14psi if everything looked good but never did. With this motor being lower compression, how much can I raise the boost and still be safe on pump gas?

[Nicholas1996]

Interested in feedback from anyone running a 6870 or 6766. Especially in terms of spool time compared to a 6266. Was thinking about stepping up the turbo eventually from a 6266 JB to maybe a 6766 BB and wanted to know how much it would change when boost came in. Originally went with the 6266jb for a few reasons. First being that the motor was stock and I didn't think anything more was necessary. Second, the clutch was stock so I figured a journal bearing would spool a bit later and be easier on the clutch. Third, it was pretty cheap for a new one. However, now the motor is currently being built and I got a twin disk clutch.

Here is my setup by the way:

Maximum PSI kit (intake manifold, intercooler, spa exhaust, etc)
Precision 6266JB
Tial WG
AEM Infinity
AEM boost controller
Flexfuel
Dual In-tank walbro 450's
8AN feed, 6AN return
Radium Rail
ID1050's
30 shot of nitrous (never actually used and probably wont. Had it and just threw it in to be ridiculous)
Motor (in the works, machined, new bearings, etc. Here are the highlights)
-CP 9.5:1 pistons (87.25mm)
-Carillo rods
-ARP L19 headstuds
-Supertech valve springs
DKM twin disk clutch

I didn't know things like pistons took 5 weeks, plus things are just out of stock from covid, so the motor is currently waiting at the machine shop. Once they have everything it should be quick, so I am hoping to have the car running by the end of August. I am happy with the 6266 and will run that for a bit, but with all this cash into the motor, I feel like it would be a waste not at least have a tune that steps it up a bit lol. It is worth noting that I have a map for E85 but mostly run pump 93. I can step up the boost on the new motor but on pump gas I wouldn't go crazy. So I am also wondering if the amount of boost it would take a 6766 to match the power of a 6266 at say 20psi would be significantly less or just negligible.


Eventually I am going to change the turbo to a ball bearing, but my question is if there is much of a benefit to a 6766BB or 6870 over the 6266BB or 6466BB which most people use.

On a side note, on stock motor on pump 93, I was running 12psi at most. The car had a base map that ran fine but was really just meant to be safe for the time being. Might have gone to maybe 14psi if everything looked good but never did. With this motor being lower compression, how much can I raise the boost and still be safe on pump gas?

Honestly 12 psi on pump gas already sounds dangerous haha. Wouldn’t go more on that stock motor. The 6466 I think is a great turbo from what I’ve read. I’m more concerned about the 6870 actually fitting down there. Also to note I’m weary of precision with the less than stellar reliability. Throwing that much money at a 6870 and it blowing oil everywhere would suck. Same goes with the 6466. The thing I’m curious about is: does the 6870 fit on a bottom mount? If so what AR? If anyone is running a top mount manifold what do they recommend? I asked PPF about the manifold they make and they said it only fits a 6766 or a 6870 with the small VBand t3 flange.

[Mspir3d]

Yeah that's a ton of boost for pump gas on a stock engine. With the lower compression ratio you'll be able to run more. Maxpsi doesn't recommend more than 9 psi on pump and 13psi on 100 oct. I've run up to 10.x psi on pump. The way I understand it, if you have a 6766 theres not enough benefit to go to a 6870. There's some threads that talk about it if you google commanderwiggin turbo comparison. He didnt compare them directly but there's some good discussion. My 6266 failed and was leaking oil before I went to the larger BW. The price to rebuild a ball bearing unit is much more prohibitive than journal bearing.

[mleveroni]

Honestly 12 psi on pump gas already sounds dangerous haha. Wouldn’t go more on that stock motor. The 6466 I think is a great turbo from what I’ve read. I’m more concerned about the 6870 actually fitting down there. Also to note I’m weary of precision with the less than stellar reliability. Throwing that much money at a 6870 and it blowing oil everywhere would suck. Same goes with the 6466. The thing I’m curious about is: does the 6870 fit on a bottom mount? If so what AR? If anyone is running a top mount manifold what do they recommend? I asked PPF about the manifold they make and they said it only fits a 6766 or a 6870 with the small VBand t3 flange.

I think 12psi is probably safe if the motor is in decent shape and the tune is right.I do agree that beyond that is pushing it on a stock motor with pump fuel. I believe the MaximumPSI shop car that made like 900hp on a stock bottom end ran the SPA cast manifold with a 6870, not sure what AR. I can't find the actual dimensions of either turbos but I would think if you are already setup for a 6266, a 6870 would bolt up with the exhaust housing modification and maybe the downpipe. I haven't heard of anyone having a problem with a precision turbo as long as they buy it new, only when people buy used ones that are already trashed. That being said changing your 6266 setup to a Garrett or Borgwarner turbo wouldn't be that hard.

[Nicholas1996]

Yeah that's a ton of boost for pump gas on a stock engine. With the lower compression ratio you'll be able to run more. Maxpsi doesn't recommend more than 9 psi on pump and 13psi on 100 oct. I've run up to 10.x psi on pump. The way I understand it, if you have a 6766 theres not enough benefit to go to a 6870. There's some threads that talk about it if you google commanderwiggin turbo comparison. He didnt compare them directly but there's some good discussion. My 6266 failed and was leaking oil before I went to the larger BW. The price to rebuild a ball bearing unit is much more prohibitive than journal bearing.

Man those precision turbos are kinda crappy. My buddy just told me his 6266 BB is dumping oil on the inside of his intercooler pipes at 7k miles. I’m definitely going to look into BW when mine takes a dump. Precision makes more power and spools up a ton faster but they seem to be assembled cheaply. I remember you said your BW spools slower. Is it that much slower where you miss the precision??

[mleveroni]

Yeah that's a ton of boost for pump gas on a stock engine. With the lower compression ratio you'll be able to run more. Maxpsi doesn't recommend more than 9 psi on pump and 13psi on 100 oct. I've run up to 10.x psi on pump. The way I understand it, if you have a 6766 theres not enough benefit to go to a 6870. There's some threads that talk about it if you google commanderwiggin turbo comparison. He didnt compare them directly but there's some good discussion. My 6266 failed and was leaking oil before I went to the larger BW. The price to rebuild a ball bearing unit is much more prohibitive than journal bearing.

I guess I've been hanging out with Evo and GTR people who all tell me to run 30psi on pump gas lol. I took a look at that turbo comparison, which is probably higher than I want to go, especially since im going to be running 93 pump fuel 95% of the time. But it does answer some of my questions, on how more lag a bigger turbo would have and how much more power it would make at a certain boost pressure.The 6266 came on just after 3000rpm, but I was not expecting the 6870 to come in around 4000rpm. So I am definitely focusing on the 6766bb or 6466bb. However, I wasn't aware problems with precision were common. I was actually planning on getting a Garrett GTW3884 before I realized the kit was meant for Precision. I assumed I wouldn't have the 6266 for long and it was around $800 without the exhaust housing so that was fine for me. When I upgrade this one I would like to run it for a while, so if I am better off changing to a Garrett or Borgwarner, what would be comparable to a precision 6766bb turbo?

[Mspir3d]

Man those precision turbos are kinda crappy. My buddy just told me his 6266 is dumping oil on the inside of his intercooler pipes at 7k miles. I’m definitely going to look into BW when mine takes a dump. Precision makes more power and spools up a ton faster but they seem to be assembled cheaply. I remember you said your BW spools slower. Is it that much slower where you miss the precision??

The spool on the 6266 was really fast and hits hard whereas it feels like the BW spools up around 4500rpm and just continues to build. I did miss the quick spool for a while but I was running stock internals until this year and the shop said the bigger turbo was better for the rods at higher boost levels. I've seen some posts that make me believe maxpsi will make the BW their new standard turbo when they re-release their kit. I could be completely wrong though.

QUOTE=mleveroni;n46243]

I guess I've been hanging out with Evo and GTR people who all tell me to run 30psi on pump gas lol. I assumed I wouldn't have the 6266 for long and it was around $800 without the exhaust housing so that was fine for me. When I upgrade this one I would like to run it for a while, so if I am better off changing to a Garrett or Borgwarner, what would be comparable to a precision 6766bb turbo? [/QUOTE]

I believe precision reliability has gotten better in recent years from what I've read. I dont have any hard facts on that though. In my case mine sucked a little aluminum from the intake rubbing the sway bar and I'd assume that's what caused the failure. I have it taken apart but haven't bothered to really look at it in the last year. I'm not very familiar with how BW names their turbos and how they compare to Precision. Precision refuses to publish compressor maps or flow data for their turbos. The turbo I'm currently on is a s364sxe. My intake manifold was cracked from front to back when I dynoed it so my numbers weren't very accurate with the loss of pressure at redline. It still made really good power though on stock internals.

[Nicholas1996]

https://www.e46fanatics.com/threads/...-gen2.1075596/

I wish they pushed the 6766 to 34 psi like the 6870 to see what it would make.
but I guess the 740whp 624wtq @ 23psi for the 6766 and the 784whp 625wtq @ 21psi for the 6870 is the closest for comparison.

[Mspir3d]

Good find. The numbers for the 6766 @23psi look very similar to the s364sxe I run.

[Nicholas1996]

Good find. The numbers for the 6766 @23psi look very similar to the s364sxe I run.

How does your curve look? Honestly I’m trying to avoid getting another precision(unless I get a deal on one). So BW may be the way for me. What AR you running?

[Mspir3d]

Here is the dyno from last year. Unfortunately their rpm hookup wasnt working at the time and we couldn't figure out why it was dropping so much boost at redline. Turned out the intake manifold was cracked from front to back...

[Nicholas1996]

I want to give bw a try. Your graph doesn’t look bad at all. Maybe give the BB turbos they offer a try and see what they do. My precision is starting to leak oil too. Garbage turbo.

[mleveroni]

What are the thoughts on a Garret GTX3584RS or a GTX3582R?

[Nicholas1996]

Never really dealt with them. But Garrett’s make a lot of good oem turbo.