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This seems slow to me

Discussion pertaining to positive pressure E28s.
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turbodan
Posts: 9246
Joined: Jan 09, 2007 10:19 PM

This seems slow to me

Post by turbodan »

This is a quick video of a 60-100 run in my 528. The car felt like it was hauling ass, but I finally got to run some guys I had before and it was a bit closer than I had hoped. Its running about 160 kpa MAP, which is about 11 psi above atmospheric up here. It would be about 9 psi at sea level, so its not a ton of boost. I'll be cranking it up as soon as I get some wastegate springs, but this is it for now:
http://www.youtube.com/watch?v=rz_Oy8SxrEw
Doesnt seem so fast, does it?
bimmerboy
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Joined: Oct 18, 2006 7:06 PM
Location: United States

Post by bimmerboy »

seems pretty damn fast to me. It seems to be faster than my saab, which would rape srt-4s from 50. Then again I don't have a turbo e28 yet, and never saw yours at 20psi



Edit, the t04 is far behind the gtxxrs in terms of technology, right? Is it any bigger to make up for this? Maybe that could equal out the manifold improvement.
turbodan
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Joined: Jan 09, 2007 10:19 PM

Post by turbodan »

The turbo isnt holding anything back. The technology shows itself in terms of spool up and response, not so much as far as outright power. The motor is going to run the same on the same amount of boost no matter what you have mashing it in there. The differences are in the losses you have on the exhaust side. The T series turbo isnt bad at all, and the TCD manifold and external wastegate are far superior to the 524td manifold and internally gated GT series turbo.

I guess I'll have to see what the new equipment does at 1.2-1.4 bar, assuming the Cometic MLS is going to be good for it. As it is right now it leaks a little coolant externally, which seems to be about on par with everyone elses experience with them. As long as it holds together, theres no reason that this motor shouldnt make 450 at the wheels. The 50 trim will do it, and I can get injectors that will support it.

It just seems slow as it is now. Apparently my butt dyno slowed down in the eleven weeks I spent daily driving an auto eta.
bimmerboy
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Location: United States

Post by bimmerboy »

turbodan wrote:The turbo isnt holding anything back. The technology shows itself in terms of spool up and response, not so much as far as outright power. The motor is going to run the same on the same amount of boost no matter what you have mashing it in there. The differences are in the losses you have on the exhaust side. The T series turbo isnt bad at all, and the TCD manifold and external wastegate are far superior to the 524td manifold and internally gated GT series turbo.

I guess I'll have to see what the new equipment does at 1.2-1.4 bar, assuming the Cometic MLS is going to be good for it. As it is right now it leaks a little coolant externally, which seems to be about on par with everyone elses experience with them. As long as it holds together, theres no reason that this motor shouldnt make 450 at the wheels. The 50 trim will do it, and I can get injectors that will support it.

It just seems slow as it is now. Apparently my butt dyno slowed down in the eleven weeks I spent daily driving an auto eta.
Excuse my ignorance on Garrett turbos, but are these the same size? If they spool the same, I would guess the t04 would be quite a bit smaller, and therefore would be making less power at similar boosts. Todd only put down 388 at 18psi with a 60 trim, is a 50trim really good for 450whp?
turbodan
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Post by turbodan »

The T04E series turbos are odd in that the 50 trim flows more than the 54 and 57 trim turbos and almost as much as the 60 trim. The 50 trim peaks at around 48 pounds a minute, and the 60 trim can do just over 50. 450 rwhp would require about 45 pounds a minute, maybe a little more like 47 or 48 depending on the engines efficiency at that power level.

If I were to run 1.4 bar, my motor should be moving around 40 pounds a minute near redline, which should be good for around 400 rwhp. Thats a pressure ratio of 2.4, which is even a little low for the 50 trim T04E in terms of maximum capacity. If I kicked it up to around 1.6 bar, it would be approaching 44 pounds a minute at redline. So the motor could make 450 rwhp with between 1.6 and 1.7 bar boost pressure if it runs efficiently enough to make that much out of the air its moving. So yes, the 50 trim could do 450 rwhp if it were wrung all the way out. I hope to test my hypothesis eventually.

To get a full 50 pounds a minute from a 60 trim you would need to be running about 20 psi boost. So if you make 388 rwhp at 18 psi means your motor isnt using all of the turbochargers capacity, which is good. You want to have some room on the compression map as opposed to running close to one edge or another.

My old GT2871 was quite a bit smaller than the T4 thats in there now, especially on the turbine side. The T4 turbine wheel uses something like a 2.5" exducer diameter, which dwarfs the 53mm diameter of the 2871. The compressors are similar, with the T04E being slighty larger. The result is a freer flowing and slightly laggier turbo. It felt about the same at first, but when I got out on the street and made some runs it was clear that the itty bitty ball bearing GT turbo was a little quicker to get going. Thats okay though. It was too small and not nearly as efficient on the turbine side as the big T4.
Mr. E28
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Post by Mr. E28 »

No sound? Did you compare your acceleration against that 335i? You walked away from it pretty nicely in those other videos.
turbodan
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Post by turbodan »

No sound on that camera. For the video its running only 11 psi or so, which is more like 9 psi would be at sea level. The runs against the 335 were on about 16 psi.

Needs moar boost. The AFR's are looking good, and the timing map worked on this motor with higher compression, so I guess its time to crank it up.
Jeremy
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Beamter
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Post by Jeremy »

turbodan wrote:No sound on that camera. For the video its running only 11 psi or so, which is more like 9 psi would be at sea level. The runs against the 335 were on about 16 psi.

Needs moar boost. The AFR's are looking good, and the timing map worked on this motor with higher compression, so I guess its time to crank it up.
Refresh my memory, what do you use for boost control? Do you just change the wastegate spring or do you use something more elaborate?

Jeremy
turbodan
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Joined: Jan 09, 2007 10:19 PM

Post by turbodan »

Jeremy wrote:
turbodan wrote:No sound on that camera. For the video its running only 11 psi or so, which is more like 9 psi would be at sea level. The runs against the 335 were on about 16 psi.

Needs moar boost. The AFR's are looking good, and the timing map worked on this motor with higher compression, so I guess its time to crank it up.
Refresh my memory, what do you use for boost control? Do you just change the wastegate spring or do you use something more elaborate?

Jeremy
For the video I was just running on the wastegate spring.

At the moment I'm using a ball and spring style manual boost controller in the wastegate signal line. Thats just until I get some stronger springs for the wastegate though. I've got it set to make about 17 on spool-up, which tapers to about 15 by the time I shift. Its not as nice as just running on the wastegate because the boost spikes up more abruptly until it opens the MBC, which then slams the wastegate all the way open all at once.
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