Turbo Talk

[easy60]

I have been on the fence between STK or a new set of 19T's in my E60. I have a thread in the E60 forum about different STK that fit the E60 Chassis, and it seems there are really only 2 that fit within my budget (JackFab or BimmerFab) and the general consensus on that forum is that nobody really likes either kit. Which is a bit dissapointing, as I think we are all aware of the difference in power potential between Twins and Singles. During this search to find the best turbo/turbos I have come across another interesting point; the TDO4L vs TDO4HL for 19T's. The TDO4L is the typical 19T I think we are all familiar with (Compressor 46/58, Turbine 41.2/47) and then there is the TDO4HL-19T (Compressor 46/58, Turbine 45.6/52) I believe the Hydra, Arashi, TR, Kinugawa, and SteamSpeed are the only TDO4HL-19T (pretty sure the Pure Stage 2 Hi-Flow are also HL's but that I can't confirm), at least thats what I have been able to find. What I haven't been able to find are flow rates in comparison to the TDO4L-19T. I see Hydra released flow rates for their HL's (HP800) at 74LBS/Min, so I would assume the others are roughly equivalent to that flow rate. What I am interested in are flow rates of the TDO4L, 6466 .96 A/R, Pulsar 3584 .82 A/R. As well as any personal experience with any of the aforementioned turbos, as I can't seem to make up my mind on the turbo/s.

A few aspects that are continuing to keep me on the fence from pulling the trigger on a STK; altitude impacting spool, and fitment issues on the E60. Another set of twins concerns me since they aren't too much less than a single kit (800-2,000 depending on the turbo/s), they do have a lower power potential especially at altitude, and low-end torque causing damage. I am not really looking to set any world records, but I would like to be in the 600whp range on E85, and an even better goal is the least amount of down-time during the swap. I currently am running VIV 19T's that are nearing the end of their life, PI, Reflex+, fueling, etc... So really only looking at turbo changes, and potentially adding an additional lpfp which doesn't really concern my bottom line.

 

[Maroon_e90]

If you're truly aiming for around 600whp, you'd want flow rates in the ballpark of 60 lb/min. The turbos you mentioned (6466 and 3584) flow closer to 90 lb/min and won’t spool until around 4,400 RPM, which can definitely affect street drivability. Single turbo kits are more expensive, harder to tune, and significantly change how the engine behaves, but it sounds like you're already aware of that. Given your goals, I'd recommend looking into a Garrett G30-770, Pulsar 5855G, or Precision Next Gen 5658 with a .82 A/R. These turbos flow around 70 lb/min and should offer hybrid-like spool with much better top-end potential.

Also there are some budget friendly journal bearing turbos on ebay if you are super concerned about cost. Here is a super budget friendly turbo that should meet your requirements. (smaller A/R since the turbine is much larger)

 

[island road]

I have been on the fence between STK or a new set of 19T's in my E60. I have a thread in the E60 forum about different STK that fit the E60 Chassis, and it seems there are really only 2 that fit within my budget (JackFab or BimmerFab) and the general consensus on that forum is that nobody really likes either kit. Which is a bit dissapointing, as I think we are all aware of the difference in power potential between Twins and Singles. During this search to find the best turbo/turbos I have come across another interesting point; the TDO4L vs TDO4HL for 19T's. The TDO4L is the typical 19T I think we are all familiar with (Compressor 46/58, Turbine 41.2/47) and then there is the TDO4HL-19T (Compressor 46/58, Turbine 45.6/52) I believe the Hydra, Arashi, TR, Kinugawa, and SteamSpeed are the only TDO4HL-19T (pretty sure the Pure Stage 2 Hi-Flow are also HL's but that I can't confirm), at least thats what I have been able to find. What I haven't been able to find are flow rates in comparison to the TDO4L-19T. I see Hydra released flow rates for their HL's (HP800) at 74LBS/Min, so I would assume the others are roughly equivalent to that flow rate. What I am interested in are flow rates of the TDO4L, 6466 .96 A/R, Pulsar 3584 .82 A/R. As well as any personal experience with any of the aforementioned turbos, as I can't seem to make up my mind on the turbo/s.

A few aspects that are continuing to keep me on the fence from pulling the trigger on a STK; altitude impacting spool, and fitment issues on the E60. Another set of twins concerns me since they aren't too much less than a single kit (800-2,000 depending on the turbo/s), they do have a lower power potential especially at altitude, and low-end torque causing damage. I am not really looking to set any world records, but I would like to be in the 600whp range on E85, and an even better goal is the least amount of down-time during the swap. I currently am running VIV 19T's that are nearing the end of their life, PI, Reflex+, fueling, etc... So really only looking at turbo changes, and potentially adding an additional lpfp which doesn't really concern my bottom line.

I had the @Hydra Performance Kit on my E61 and it performed brilliantly. It was only the Stage 1 kit, but I wouldn’t hesitate to go that route again. In fact, if I were doing twins again on the N54, Hydra would be the only kit I’d consider. Based on your power goals, you should be looking into the Stage HP800 along with the Overdrive kit.

As for the two turbo kits you mentioned—good luck, I guess. One of my other E61s is currently in the process of having a custom twin-scroll divided manifold built with an EFR configuration. That said, with the E6X chassis, I removed everything from the passenger side — A/C lines, DSC pump, coolant tank, etc. Once cleared, the platform actually offers more working room than the E9X for a proper setup.

We just finished installing the N52 head on the block. I’ll post some pics once more of the build comes together.

 

[easy60]

If you're truly aiming for around 600whp, you'd want flow rates in the ballpark of 60 lb/min. The turbos you mentioned (6466 and 3584) flow closer to 90 lb/min and won’t spool until around 4,400 RPM, which can definitely affect street drivability. Single turbo kits are more expensive, harder to tune, and significantly change how the engine behaves, but it sounds like you're already aware of that. Given your goals, I'd recommend looking into a Garrett G30-770, Pulsar 5855G, or Precision Next Gen 5658 with a .82 A/R. These turbos flow around 70 lb/min and should offer hybrid-like spool with much better top-end potential.

Also there are some budget friendly journal bearing turbos on ebay if you are super concerned about cost. Here is a super budget friendly turbo that should meet your requirements. (smaller A/R since the turbine is much larger)

Since I am aiming for 600WHP, trying to do that at 5500+Feet of elevation, and a pretty regular DA of 7K+ it makes it really difficult for hybrids to spool/make enough pressure to feed that power level, or so I have been told. For twins I am leaning more towards the Arashi Ball Bearing HL 19T's, over the other mentioned turbos, mostly because I like the customer service of Arashi, they have been super responsive to questions and sales inquiries, plus the kit just looks nice, and the price is a little too hard to resist.

But a single would add another level of fun, since it would be fairly easy to knock into the 700's, so power growth potential is much nicer, and I can't argue with the fact singles just look pretty killer. I am Wedge Tuned, and have had a really excellent experience with Ken, so I feel tuning is well secured. The other aspect of singles that I do like is they limit low end torque which likes to kill N54's, plus I am not really sure how twins impact heat vs a top mount, pretty sure heat builds more with a top mount over twins, but to make the same level of power with a 6466 or 6262 as 19T's there is a pretty significant pressure difference, and at 28-30psi on twins is pretty much the limit of their usable pressure range which is going to lead to higher IAT (I think?), and the E60's can't run bottom mounts due to the motor mount.

As far as budget goes, 4K is about what I am willing to spend on just the Single Kit, so not super tight, but not enough of a budget to go with a VIE or JNC but BimmerFab, SpeedTech, and JackFab are within that range. As far as spool is concerned I'm rocking some older China 19T's that have been great, and have lasted a good bit of mileage at 28-30lbs on E85, but they don't make full boost early at all, they have fairly substantial lag, and drivability is only getting worse with age/mileage, so a bigger single (likely looking between a 6262 or 6466) would likely give me similar spool, and I do like the ability to make the same numbers as 19T's at 30psi with a single at 20ish psi.

 

[easy60]

I had the @Hydra Performance Kit on my E61 and it performed brilliantly. It was only the Stage 1 kit, but I wouldn’t hesitate to go that route again. In fact, if I were doing twins again on the N54, Hydra would be the only kit I’d consider. Based on your power goals, you should be looking into the Stage HP800 along with the Overdrive kit.

As for the two turbo kits you mentioned—good luck, I guess. One of my other E61s is currently in the process of having a custom twin-scroll divided manifold built with an EFR configuration. That said, with the E6X chassis, I removed everything from the passenger side — A/C lines, DSC pump, coolant tank, etc. Once cleared, the platform actually offers more working room than the E9X for a proper setup.

We just finished installing the N52 head on the block. I’ll post some pics once more of the build comes together.

My biggest gripe with the Hydra HP800's is the price tag, 3200+ is a little steep IMO for twins, not saying they aren't worth it (as I have 0 experience with them, and by all accounts they seem widely adored) I just don't know if spending STK money on twins is really a smart move for me, especially considering I am not 100% sold either way, I would much rather spend 2Kish ion twins, and if I decide after a year that I should have gone single, I have much less of an investment into the turbos, so selling twins and going to a single makes for a more reasonable justification with my better half.

I have talked, at nauseum, with several fabricators, vendors, and customers about E60 single kits, and most say, shoving down the ABS/DSC module is doable to fit most top mount kits, not saying I wouldn't look into moving things over, but to get the car operational after a weekend, seems like the best course of action would be retaining as many factory located items as possible.

Any reason you went with the N52 head over the N53?

 

[Maroon_e90]

When do your current twins hit 20 psi?

I did some math, and those Arashi twins are actually pretty close in size to a 6466 — roughly a 64.5x82mm compressor and 64x70mm turbine. The main difference is the A/R — they're running a 0.41 A/R, which is equivalent to around a 0.63 A/R on a single turbo setup. Most people would go with a 0.84 or even a 0.96 for better flow on a single. They’re also ball bearing, so you should see slightly faster spool, maybe a few hundred RPM earlier which is a nice upgrade.

That said, they’re still a bit oversized for your 600whp goal. The bigger concern, in my opinion, is the small wastegates. When choosing a turbo, it's important to consider turbine flow. No turbine flows 100% of the engine's exhaust — that's why having properly sized wastegates is crucial to avoid excessive backpressure. These Arashi turbines are similar in size to Garrett’s 62x68mm units, and based on flow data from Garrett, we can estimate that a turbine with such a low A/R will flow around 22-25 lb/min. So where does the remaining ~35 lb/min (assuming you're flowing ~60 lb/min total) need to go? Through the wastegates. Now, singles typically run a 44mm (1.73”) or 45mm (1.77”) external wastegate, which flows a lot more than the small internal wastegate ports on twin setups. That could explain why people often need to run significantly more boost on twins to hit the same power levels as singles there's just more backpressure choking the flow.

 

[easy60]

When do your current twins hit 20 psi?

I did some math, and those Arashi twins are actually pretty close in size to a 6466 — roughly a 64.5x82mm compressor and 64x70mm turbine. The main difference is the A/R — they're running a 0.41 A/R, which is equivalent to around a 0.63 A/R on a single turbo setup. Most people would go with a 0.84 or even a 0.96 for better flow on a single. They’re also ball bearing, so you should see slightly faster spool, maybe a few hundred RPM earlier which is a nice upgrade.

That said, they’re still a bit oversized for your 600whp goal. The bigger concern, in my opinion, is the small wastegates. When choosing a turbo, it's important to consider turbine flow. No turbine flows 100% of the engine's exhaust — that's why having properly sized wastegates is crucial to avoid excessive backpressure. These Arashi turbines are similar in size to Garrett’s 62x68mm units, and based on flow data from Garrett, we can estimate that a turbine with such a low A/R will flow around 22-25 lb/min. So where does the remaining ~35 lb/min (assuming you're flowing ~60 lb/min total) need to go? Through the wastegates. Now, singles typically run a 44mm (1.73”) or 45mm (1.77”) external wastegate, which flows a lot more than the small internal wastegate ports on twin setups. That could explain why people often need to run significantly more boost on twins to hit the same power levels as singles there's just more backpressure choking the flow.

Current twins hit 20psi at 3900, 28psi follows relatively quickly after at 4700.

Arashi is a 46/58 compressor, and 45.6/52 turbine, where the 6262 is a 62/76 compressor, and 68/62 turbine, they also have pretty substantially different flow rates, and A/R is about double that of the Arashi. So the Arashi turbos would be great for spool, great for low and mid range, but they aren't going to have the power potential of the 6262, and boost pressure to boost pressure the 6262 should outperform the twins by a significant margin (at least that should be accurate)

The 600whp+ goal is the bottom end of the spectrum for either direction, at altitude I know the twins are going to struggle to make much more than 650whp though, or at least that seems to be the results from most at altitude. I would love to make 700 on twins w/ e85, but I really doubt that as a possibility due mostly to the garbage air up here in Colorado.

I know the flow rates of a single are going to pretty largely eclipse that of twins, as they have more volume, but I would still like to know flow rates of the turbo options I am considering.

 

[Maroon_e90]

I think you missed my point. Two arashis at 46/58 and 45.6/52 is equivalent flow rate to a single 64.5/82 and 64/70. Likewise two turbos at .41 ar is roughly equivalent to a single at .63 ar.

 

[easy60]

I think you missed my point. Two arashis at 46/58 and 45.6/52 is equivalent flow rate to a single 64.5/82 and 64/70. Likewise two turbos at .41 ar is roughly equivalent to a single at .63 ar.

I most certainly did lol, my bad