I need turbo specs!

[photo500]

Ok guys despite the fact im in far flung Western Australia I'm going to attempt to Turbo my 535i. What I'm having trouble with is which turbo to go for. It seems alot of you use the T04 with an external wastegate and thats fine with me. The problem is I need the specs! The compressor and housing numbers etc. Does anyone have these from a setup that has minimal to no lag such as the TCD kits are meant to have. I could buy one from TCD or similar but I really would like local backup and support. But without specs I have no idea what to ask for
I plan to only run 10psi and will be using a b35 head and pistons. My manifold is the BAE type and suits the T04 with a stud adapter.(currently has T04 throat but T3 bolt holes) Help!

[GregATL]

I hate giving you an incomplete answer but my car is 1500 miles from me and I can't remember the A/R's for my TCD Turbo. It's off the car currently so it would have been easy to check.

Turbo is a T04E. I want to say the compressor housing is .82 A/R and the turbine is .63 A/R. It's very close to these I am sure.

TCD has very good support BTW. Just a phone call away usually. I understand the time difference could be a factor however.

Now if you want my opinion, and you had the extra money for it I would say get a Garrett GT3582R ball bearing turbo. It should spool very quickly on these motors and the compressor wheels on them are very efficient. I had considered one when planning for mine but the exhaust housings were offset which wouldn't work on an e28 in a bottom mount configuration which is what I had to work with at the time. I am assumming, hopefully not wrongly, that you have a RHD car and it will be top mounted.

Good luck with your project. Let us know how it's progressing.

[///ARINUTS...]

What you want to is 2 things for optimal boost and quick spooling.

#1 is to find a turbo big enough for your power goals and with a divided entry turbine housing, I would think a Holset HX40 is a good choice.

#2 is build a proper manifold for it, or even just an adapter for the factory manifolds, keeping the pulses seperate.

keeping the pulses seperate with a divide flange greatly aids in spool up.

you need this flange:




Big Bronze Rim made an adapter that basically keeps the pulses seperate.

I think 666 fab might have one available too.

[turbodan]

Holset turbos are for trucks.


I've never had a problem with spool running undivided turbine housings. I would bet that most of the gain in spool time with divided turbines is from the reduction in cross sectional flow area . I hear a lot about maintaining exhaust pulses up to the turbine, but it seems like the only OE application of this technology is in low rpm diesel motors. I'm pretty sure that you dont really gain anything from divided inlets when your turbo is sized to spool over 3000 rpm. The actual gas flow through the turbine will spool it up, wether or not the exhaust pulses are intact will make a slight , slight difference. Like I said, it might only be worthwhile on low RPM motors.

[///ARINUTS...]

Holset turbos are for trucks.

Could you please explain the difference between truck turbos and car turbos? Thanks

[turbodan]

Not that I could be specific, but truck turbos are designed for power at low engine speeds on large motors. A "car turbo" like a GT3582R is designed for power at high engine speeds on medium/small motors.

I'm not an engineer, I'm just saying that Holset turbos arent like "OMGBBQ". I'll take a Garrett turbo with readily available compression maps any day.

[photo500]

Those Garrett turbo's look pretty good, I like the idea of water cooling as well. They are pretty pricey though by the looks. About $1250 USD. Anybody remember how much they paid for their TCD turbo? Maybe I should just get one of those if the backup is ok.

Adam

[vance]

Holset turbos are for trucks.

And I'm sure that's why the Swedish guys have such success with it on their high horsepower engines.

I hear a lot about maintaining exhaust pulses up to the turbine, but it seems like the only OE application of this technology is in low rpm diesel motors.

This technology is also incorporated on the new Lancer and WRX STI, not exactly a diesel application.

Vance

[Jeremy]

This technology is also incorporated on the new Lancer and WRX STI, not exactly a diesel application.

Vance

The Holset turbos are generally the wrong size of our motors, Dan is right. Generally, motors for trucks and adapted for use in cars have one of two characteristics:

They spool really late but move a huge amount of air and make fantastical top end power (like those crazy swedes do).

They spool nicely but power drops off high in the rpm range because the turbo can't move enough air to continue to make power.

The STi and EVO motors are both trying to make big power from relatively small displacements, running high boost (does the EVO still come from the factory set at 20psi?). Spooling big turbos for a usable midrange is a problem in their case, besides which those cars both use 4 valve/cyl motors which is almost an entirely different ballgame when it comes to boost.

The other characteristic that truck turbos have is that they generally hit REALLY REALLY hard when boost comes on. This may be a desirable trait for some, but I prefer a slightly more linear, driveable experience.

Ari and vance, not to say that knowledge can't be there without it, but do either of you have any actual experience with BMW m30 turbo cars?

Jeremy

[vance]

Jeremy, I was refering to Dan's comment about split housing turbos OE use being limited to "low rpm diesel motors", hence the reference to Lancers and the STi. Both of these applications use this technology for faster spool up. And the Holset HX40 turbo may "generally be the wrong size" for an m30, but there are different sized Holsets besides the hx40 and hx35 and with his location in Australia, the Holset stuff maybe more readily available than a Garrett unit. And also Jeremy to answer your question about m30 turbo ownership, I've owned a lowly '85 745i for the last five years, but technically it's an m106. I've also built a high 12 second '86 2.3l 4cyl SVO Mustang, a couple of low 11 second v-8 Mustangs one with a super charger and one with nitrous, so I've pretty much run the gamut on forced induction still believe one of the most important things is being able to read your spark plugs. My day job is parts sales and technical trouble shooting for a Mack/Volvo/Mitsubishi/Cummins truck dealership, so inadvertently thats where my like for the Holset comes in. I also like puppies,long walks on the beach, and cook one of the best rib eye steaks you've ever put in your mouth.

Vance

[///ARINUTS...]

OK, I don't want to start an argument here. I was a non believer also until I tried it after so many other people reported with great results.

Volvo guys and Ford 2.3L use the HX35 regularly. there was a site called Turbobrick.com or something like that. the majority of volvo 4,5,&6cyl were using Holsets.

take 2 identical turbos , one with a divided entry turbine housing and a proper manifold designed to keep the pulses separated, and then one without a divided entry turbine housing , and at this point the manifold would not really matter, guess which one will get to the same full boost first. and guess which one starts building boost first. The split housing directs the air to a different spot on the turbine wheel, somehow, from my limited understanding, when the pulses are sperated, this makes the turbo spool quicker. The divided turbine housing is a better housing from an efficiency standpoint, but if you don't use a split pulse adapter and separate the exhaust pulses from the cylinders (123 and 456) you will not gain the spool advantage of this type of housing and it will seem large and sluggish.

I have a HX35 on my m20 and I thought it would never spool. When It spooled almost as quick as the super 60 t3 I had before it, I was very surprised, amazed and convinced. and where the t3 would die off at 1 bar of boost at anything over 4500rpm, the HX35 would keep pulling strong; also EGT are never as high as they used to be with the small T3.

Not saying that anyone turbo system is not up to snuff, just giving you my opinion and experiences.

Now onto the differences between truck turbos and car turbos and diesel turbos and gasoline turbo. There is no difference. Turbos don't have a camshaft, or a cam profile. A Turbo is a Turbo, yes it will act differently depending on the engine, but that doesn't mean you can't use a diesel truck turbo in a gas car. You just have to properly choose the right size turbo for the engine.

an HX40 is perfect for most M30 B34 engines. If you don't care for high Boost and want quicker spool a smaller turbine housing or even a HX35 might work, and for more boost at the cost of some lag , you would use a larger turbo like a HX55. But generally speaking , you can't go wrong with a HX40.

Holset Turbos are THE REAL DEAL. They have a very strong Research and technology unit. thats why they out perform the classic garrett units.

[Jeremy]

Good, now that everyone's credentials are settled, we can get down to business. No offense was intended, btw, I just like to know where people's knowledge (or lack thereof in some cases) comes from.

Ari, with the two "identical" turbos you talked about. We're talking same flange (t3, t4), same specs (compressor/turbine housing, etc), everything?

Do Holsets even use the same flange as a Garret? I don't honestly know. Comparing a t3 flange turbo to a t4 isn't really fair though, that much I do know. The availability factor I hadn't considered, but I'm not a big fan of used turbos.

Jeremy

[///ARINUTS...]

Ari, with the two "identical" turbos you talked about. We're talking same flange (t3, t4), same specs (compressor/turbine housing, etc), everything?

YES! (also, holset does make turbine housings that are not divided, but they are not as common anymore )

Do Holsets even use the same flange as a Garret? I don't honestly know. Comparing a t3 flange turbo to a t4 isn't really fair though, that much I do know. The availability factor I hadn't considered, but I'm not a big fan of used turbos.

The HX35 I have has a T3 inlet flange, Some HX40s also have a T3 inlet flange , but some have a T4 Flange , It depends on the size of the turbine housing. You can have different turbine housings, effectively choosing the right one for your application. the HX35 I have had a 12cm^3 turbine housing with an internal wastegate , I did want a slightly larger turbine housing with out the internal wastegate assembly as it took up some critical area / room inmy engine bay. I had found and purchased an 18cm^3, it was a little larger than I had hoped for but it solved my problem at the time. If I had the time an opportunity to find either a 14 cm^3 or a 16cm^3 turbine housing, I would have chosen that, but that being said I am happy with the 18cm^3 and won't take the system apart to change it. Also the nice thing about knowing the actual size of the housing is that no matter which flange is on it, the size doesn't change, where as with A/R ratios, What Jeremy said above applies, a T3 .60 a/r is very different than a T4 .60 a/r.
An all my holset turbo parts were bought used and they have not been rebuilt and they continue to run strong.

[vance]

No offense taken at all Jeremy. You never know who is on the other end of the keyboard.

Vance

[eddycooper]

See this website for compressor maps and other helpful turbo tools.

http://www.squirrelpf.com/

The people in the Turbo Dodge world (think 80s K-car) are very well-versed in turbo theory and this website is one example.

Eddy

[turbodan]

I've never seen a shred of actual evidence that Holset turbos are in any way better than Garrett turbochargers. I'm sure they're the "real deal" but you cant seriously try to tell me that you dont think Garrett has decades of R&D in thier own designs.

You went from a T3 Super 60, which is a very small turbo, to a much larger Holset. This is obviously going to be a noticeable upgrade. I went from a smaller Garrett to a larger Garrett, and it was also a big upgrade.

If it were possible, I would suggest you try comparing a Garrett to a Holset with the same wheel sizes and trims. But, since there is no common denominator between the two brands, youre just comparing different size turbos.

I'm still not seeing the need for a twin scroll turbine housing on a BMW six cylinder motor. The Lancer and STi have wee little two liter motors. I dont even think its a matter of exhaust pulses as much as it is trying to maintain high exhaust gas velocity up into the turbine. That would be at the expense of top end power, much like anything else that spools the turbo up quicker. For the same size turbine, an undivided housing will flow more gas than a divided entry. Its like using a smaller turbine AR really. I'll bet that swapping the divided entry turbo out of your new Evo will be good for quite a bit on the top end.

One example of an application of a divided entry turbo diesel motor would be the M21 from the 524td. Thats the kind of powerband that design is intended to support. Low RPM, quick spooling, usually diesel motors which dont need a lot of top end flow capacity.

But hey, I'm just sayin.

[///ARINUTS...]

You went from a T3 Super 60, which is a very small turbo, to a much larger Holset. This is obviously going to be a noticeable upgrade. I went from a smaller Garrett to a larger Garrett, and it was also a big upgrade.

Did you notice a difference in spool up? did you gain some lag?

[turbodan]

I went from a GT2871R .86 to a T04e 50 trim with a .58 AR O trim turbine. The spool up and boost threshold are only a little higher than the ball bearing T25. The GT2560 was much less laggy, but it choked up on the top end on the exhaust side.

[///ARINUTS...]

I went from a GT2871R .86 to a T04e 50 trim with a .58 AR O trim turbine. The spool up and boost threshold are only a little higher than the ball bearing T25. The GT2560 was much less laggy, but it choked up on the top end on the exhaust side.

So you noticed a little more lag.
and how much more boost power did you gain?

[SilverBullet]

I think that the garrett is probably more readily available here in aus. And there are way more places that would deal with them. I was looking at the turbo off the xr6t, from memory they were either gt35/40 or gt40 with internal WG. There would be a few shops around now replacing them for something better so mayb try ebay to see whats around.

[turbodan]

I went from a GT2871R .86 to a T04e 50 trim with a .58 AR O trim turbine. The spool up and boost threshold are only a little higher than the ball bearing T25. The GT2560 was much less laggy, but it choked up on the top end on the exhaust side.

So you noticed a little more lag.
and how much more boost power did you gain?

I started out with a Garrett GT2560R .64, which was insanely quick spooling, but too small on the turbine side for great top end power. Next up was a GT2871R .86, which had a higher boost threshold, but was just as quick to spool above about 3k RPM. The latest hardware is a Garrett T04E 50 trim compressor with a T4 .58 AR O trim turbine. The boost threshold is about the same as the 2871 .86 and it seems to be only slightly laggier, if at all. I only got about ten minutes in running that before I discovered that the head it went back together with was cracked, so I'm still not very familiar with it.

Its on track to be running again this weekend. During what little time I had on the new equipment it seemed to be a big improvement over the diesel manifold and internally gated T25 frame turbo.

[///ARINUTS...]

Here is your shred of actual evidence

The holset HX35s I mentioned are good for reliable 450-500 hp with their 55 mm compressor inducers, and a 60 mm turbine exducer, that's at 1.5-2.0 bar boost in the compressor map. It's quite suited for a goal of about 300 hp @ 1 bar with room to grow. With my manifold, which is a tubular ITG, which is now being sold on ebay for a fraction of What I paid. ( I'm not sure if the quality is the same, but I sure hope mine is better ) anyway, I welded in a divider in the collector to keep the pulses separated all the way to the turbo and I added a 50mm external wastegate, also keeping the pulses separated until they hit the wastegate.
Full boost of 14 psi at 3600 rpm. and it starts spooling around 2400rpm , and before when I had it set at 8psi it was all in at around 3300rpm. this is in second gear.

So compare your numbers. a proper manifold and turbo charger matching can do wonders.

[Jeremy]

Could you share that Holset compressor map and it's source, please?

Jeremy

[Badger]

from the dynos ive seen on bimmerforums the Holset turbos don't start working till 4k. They go from 200hp to 500hp in 200rpm. I don't know much about turboing yet but ive seen about 7 dynos that hit about the same rpm.

[Brad D.]

I have a couple of Holset maps on my computer at home, I will post them up tonight for those who are interested. I have no idea where I got them, but I typically save things like that incase they may be of further use to someone later.

[turbodan]

Okay, good. 55mm compressor inducer, 60mm turbine exducer. So its very similar to a GT3076R:

Looks like it'll support over 500 RWHP with a 57mm compressor inducer. The surge limit is very low, so it is quite suitable on smaller displacement motors. Garrett's website recommends it for motors down to 2 liters. Its also a ball bearing turbocharger, so you could expect reduced lag and a very long service life even under very rough conditions. Lets take a peep at the turbine flow chart:

The three lines represent the different turbine housing kits available. The turbine wheel uses a 60mm exducer diameter, just like the Holset you mentioned. With the smallest turbine housing available, flowing about 21 pounds a minute, you could expect it to fully spool around 3k rpm on a 2.7l M20. You would start making boost at 2000 rpm.

Just looking at the charts the GT series wheel designs seem to be very efficient. The 70% island is huge on the 3076 compressor, and it peaks at 77% efficiency. Thats very good. I'd compare that to a Holset, but I've never found a real, legitimate compression map for one.

[Brad D.]

Some of the 240sx guys with 2.0l sr20det engines are running the 3076. Its a pretty nice turbo capable 400+whp at 16psi. Here is an interesting thread on a TS gt3076 vs a standard 3076.
GT3076 dyno
I think with the proper AR, this would make a nice m20 or even moderate boost m30 turbo, except that for the m30, you would potentially be limited by the t3 hotside.

[turbodan]

Interesting dynos, but I think that there are too many other variables to compare the two charts. I read down the thread and it says some things about other changes the guy had made in between the runs, other than the turbo itself.

The dynos would be a little more legit if they had a plot for the boost pressure and AFR. I have a feeling these were different between the runs.

[///ARINUTS...]

How much does a GT3076R cost new? used?
I don't think you could touch a new one for under $1000 and used ones would fetch at least $500. I paid less than $150 for my used HX35, and its been working great with no issues.

I have no problem using a garrett, I use one on my 1983 Mercedes Benz 300SD.

[Brad D.]

Interesting dynos, but I think that there are too many other variables to compare the two charts. I read down the thread and it says some things about other changes the guy had made in between the runs, other than the turbo itself.

The dynos would be a little more legit if they had a plot for the boost pressure and AFR. I have a feeling these were different between the runs.

I agree completely, I just knew Jason (the owner of that car) had that turbo and quickly threw that thread up there. The turbo is definitely capable of getting the job done though and spools pretty well considering its on a 2L engine.

Cheapturbo.com (PeakBoost) has the GT3076R for $1250 new. Decent place to pick up turbos BTW.
www.cheapturbo.com