Stock CT-26 question
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C
CT-26 User
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I'm trying to find where to turn it on...sorry.
I know I'll have backpressure. I'm just trying to find a good compromise btwn backpressure, good exhaust flow past the turbine, full boost capability by 1/2 way into the rpm range, ect...
It's on a 94 V6 Camaro(3.4L or ~207 cu in). I figured since supra owners seem to have tons of experience with turbos you'd be good people to ask.
Well, I'm wanting in the 400 hp range in the 15-20psi range. The stock hp peak for this engine N/A is around 4500rpm, so I would think getting a turbo that makes it's best effieciency from 3000-4500 or so would be a good idea. But then I also don't want it to run out of flow up to 6000 rpm. Although this is a street car so only top end isn't the best option. I talked with one place and they told me a TO4-E/T3 46 trim comp, stage III turbine w/ a .63 a/r turbine housing would be the turbo for me. What do ya'll think?
Here's a couple of links of what I've done w/ the CT-26.
http://www.geocities.com/mustang732/images/turbo/recent/index.htm
http://www.geocities.com/mustang732/94_camaro.htm
I know I'll have backpressure. I'm just trying to find a good compromise btwn backpressure, good exhaust flow past the turbine, full boost capability by 1/2 way into the rpm range, ect...
It's on a 94 V6 Camaro(3.4L or ~207 cu in). I figured since supra owners seem to have tons of experience with turbos you'd be good people to ask.
Well, I'm wanting in the 400 hp range in the 15-20psi range. The stock hp peak for this engine N/A is around 4500rpm, so I would think getting a turbo that makes it's best effieciency from 3000-4500 or so would be a good idea. But then I also don't want it to run out of flow up to 6000 rpm. Although this is a street car so only top end isn't the best option. I talked with one place and they told me a TO4-E/T3 46 trim comp, stage III turbine w/ a .63 a/r turbine housing would be the turbo for me. What do ya'll think?
Here's a couple of links of what I've done w/ the CT-26.
http://www.geocities.com/mustang732/images/turbo/recent/index.htm
http://www.geocities.com/mustang732/94_camaro.htm
C
CT-26 User
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Which are you calling tiny tiny? The stock housing or the TO4-E 46? I've seen a lot of you guys upgrade to a TO4-E 60. From my looking at compressor maps, based on displacement, that one seems a little big in that it's boost threashold would be a little high and not make boost as soon.
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Trust me, thier is practicaly no lag with the ct-26 60-1 upgrade, it is the best upgrade i have ever dont to my car... and it flows WELL....
C
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Thanks ma70man
Well I wouldn't upgrade the CT-26. I would just get a whole new turbo. I made the flange for putting the CT-26 on my car so I'm not worryed about making another one. Do you know if an upgraded CT-26 to a 60 is identical on the compressor side to the characteristics of a TO4-E 60? It also looks like from the compressor maps that a 60 would do the same job at a lower turbine speed than a 46(which is what one place told me I should buy from them). I was sold on the 46 as it seems like as boost would increase it would pass through the most efficient islands on the compressor map, but then the 60 is more efficient over all, the only thing I'm worryed about is what I've read about boost threashold in a turbo that is too big(on the compressor side).
Oh, wait. I just saw that you said a 60-1 upgrade. Isn't that a TO4-B compressor? 60-1 and 62-1 I think is a TO4-B. The one I was talking about was a TO4-E 60.
Well I wouldn't upgrade the CT-26. I would just get a whole new turbo. I made the flange for putting the CT-26 on my car so I'm not worryed about making another one. Do you know if an upgraded CT-26 to a 60 is identical on the compressor side to the characteristics of a TO4-E 60? It also looks like from the compressor maps that a 60 would do the same job at a lower turbine speed than a 46(which is what one place told me I should buy from them). I was sold on the 46 as it seems like as boost would increase it would pass through the most efficient islands on the compressor map, but then the 60 is more efficient over all, the only thing I'm worryed about is what I've read about boost threashold in a turbo that is too big(on the compressor side).
Oh, wait. I just saw that you said a 60-1 upgrade. Isn't that a TO4-B compressor? 60-1 and 62-1 I think is a TO4-B. The one I was talking about was a TO4-E 60.
C
CT-26 User
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So what do ya'll think?
Could you help me out with the turbo sizing for my engine?
Could you help me out with the turbo sizing for my engine?
C
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What upgrade would you recommend? A 60-1? 60-2? Some other TO4-E upgrade?
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A CT26 upgraded to a 60-trim literally HAS a T04E 60-trim Garrett wheel inside. The physical size of the CT26 compressor housing, as I understand it, is smaller than the housing where the T04E wheels are generally used. There is much debate over how much effect this would have when plotting the curves on a compressor map. Your assumption that the 60 would move the same amount of air at a lower shaft speed than the 46 is correct. The charged air will be cooler too. The only real "downside" is slightly slower spool up, but the upgraded CTs26s spool up relatively quickly anyways. And yes, the 60-1 is a T04B.
I highly recommend taking a look at this thread. You should try some of the calculations using your engine size, rpm range and volumetric efficiency to see which wheel is best for you. If I had to take a stab in the dark, I would say 60-trim or smaller would be good for your application as I'm assuming you'll be running relatively low boost.
I highly recommend taking a look at this thread. You should try some of the calculations using your engine size, rpm range and volumetric efficiency to see which wheel is best for you. If I had to take a stab in the dark, I would say 60-trim or smaller would be good for your application as I'm assuming you'll be running relatively low boost.
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something bigger.
upgrading the CT is stupid for a number of reasons:
1. the shaft/bearings of the CT are NOT made to handle the added mass of a larger compressor....coupld that w/the increased shaft speed of people running more boost and you're asking for it...
2. stuffing a larger compressor into a SMALL housing that has been machined out for it creates LOTS of heat.....
3. the stock CT's bottleneck is the turbine, flowing more air only magnifies this
3a. no, clipping the turbine doesn't solve this. turbine clipping is a band-aid for a larger problem- TOO SMALL of a turbine. clipping the turbine drastically alters its characteristics and kills efficiency...
just MNSHO....
upgrading the CT is stupid for a number of reasons:
1. the shaft/bearings of the CT are NOT made to handle the added mass of a larger compressor....coupld that w/the increased shaft speed of people running more boost and you're asking for it...
2. stuffing a larger compressor into a SMALL housing that has been machined out for it creates LOTS of heat.....
3. the stock CT's bottleneck is the turbine, flowing more air only magnifies this
3a. no, clipping the turbine doesn't solve this. turbine clipping is a band-aid for a larger problem- TOO SMALL of a turbine. clipping the turbine drastically alters its characteristics and kills efficiency...
just MNSHO....
C
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Thanks for that link. Had some good info in it.
Well I've been doing some calculations on my own. I set up some graphs of the flow rate my engine needs at different boost levels. I used 80% VE and ambient temp of 85, and a comp. eff. of 74% just for a good average.
There are 6 graphs, one for 7, 15, 20, 22, and 25 psi.
I also put some lines on compressor maps of the 60-1, 62-1, to4e-46, and to4e-60. The colors represent different boost levels:
violet: 7psi
blue: 10psi
green: 15psi
yellow: 20psi
orange: 22psi
red: 25psi
The first vertical line of each color is the flow rate at 3000rpm, and the second is at 6000rpm.
What do you think? My motor is stock for now so I don't think I could get away with running much more than 15psi, but I have another motor just like it that I'll rebuild w/ forged lower compression ratio pistons once I figure out how low I need to make it. The stock ratio is 9:1. Which compressor would be a good match? The 46 has better low pressure/low speed eff., but the 60 has better high pressure/high speed. The 60-1 and 62-1 don't seem to be good matches since everything is to the left of the middle island.
http://www.geocities.com/mustang732/images/turbo/compmaps/
Thanks.
Well I've been doing some calculations on my own. I set up some graphs of the flow rate my engine needs at different boost levels. I used 80% VE and ambient temp of 85, and a comp. eff. of 74% just for a good average.
There are 6 graphs, one for 7, 15, 20, 22, and 25 psi.
I also put some lines on compressor maps of the 60-1, 62-1, to4e-46, and to4e-60. The colors represent different boost levels:
violet: 7psi
blue: 10psi
green: 15psi
yellow: 20psi
orange: 22psi
red: 25psi
The first vertical line of each color is the flow rate at 3000rpm, and the second is at 6000rpm.
What do you think? My motor is stock for now so I don't think I could get away with running much more than 15psi, but I have another motor just like it that I'll rebuild w/ forged lower compression ratio pistons once I figure out how low I need to make it. The stock ratio is 9:1. Which compressor would be a good match? The 46 has better low pressure/low speed eff., but the 60 has better high pressure/high speed. The 60-1 and 62-1 don't seem to be good matches since everything is to the left of the middle island.
http://www.geocities.com/mustang732/images/turbo/compmaps/
Thanks.
N
NeverNZ
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since your engine is a v6, why not do a twin turbo setup?
it would probably be easier than what you have already done
you can run 2 ct26s, and have a lot more high end room, and probably not to much loss in the low rpm
it would probably be easier than what you have already done
you can run 2 ct26s, and have a lot more high end room, and probably not to much loss in the low rpm
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2 stock ct's would be interesting....
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