20G turbo upgrade from Buschur Racing.
Jan 11, 2006, 10:03 AM
#766
Originally Posted by Drifto
I thought that 10lb/min = 144.718cfm?
CFM isn't really a good unit to use for power estimation because it doesn't consider normal changes in air density, which affect the number of O2 molecules per CF. This is why we can't just say a given lb/min = a certain CFM, unless we give a temp, humdity, and elevation. This is why compressor maps give lb/min.
1 CFM = 0.075lb/min at 70 deg F, 50% humidity, and at sea level.
- If the temp rises, lb/min drops
- If the humidity rises, lb/min drops
- If we go up in altitude, lb/min drops
Nevertheless, the 20G should come close to 700cfm at choke flow. I'm pretty certain choke flow falls outside the efficiency zone, so you'll stop making power before the turbo reaches that figure. When I quoted a GT35R as flowing 780cfm, that would be around the limit of it's efficiency, not it's choke flow (which should be somewhat higher). We can't really compare the choke flow of one turbo to the efficiency limit of another. That isn't comparing apples to apples, so sorry if not clarifying this confused anyone.
Jan 11, 2006, 10:07 AM
#767
Originally Posted by davidbuschur
Jan 11, 2006, 06:16 PM
#768
I found it here http://ztechz.net/id6.html. It may be just a general conversion but I thought you said that a stock turbo, rated at 42lb/min, flows 625cfm and the 3076, rated at 52lb/min, flows 698cfm. It seems to be too small of a difference in cfm for 10lb/min.
Originally Posted by Ted B
I'm curious as to where you found that figure, because it literally changes with the weather.
CFM isn't really a good unit to use for power estimation because it doesn't consider normal changes in air density, which affect the number of O2 molecules per CF. This is why we can't just say a given lb/min = a certain CFM, unless we give a temp, humdity, and elevation. This is why compressor maps give lb/min.
1 CFM = 0.075lb/min at 70 deg F, 50% humidity, and at sea level.
- If the temp rises, lb/min drops
- If the humidity rises, lb/min drops
- If we go up in altitude, lb/min drops
Nevertheless, the 20G should come close to 700cfm at choke flow. I'm pretty certain choke flow falls outside the efficiency zone, so you'll stop making power before the turbo reaches that figure. When I quoted a GT35R as flowing 780cfm, that would be around the limit of it's efficiency, not it's choke flow (which should be somewhat higher). We can't really compare the choke flow of one turbo to the efficiency limit of another. That isn't comparing apples to apples, so sorry if not clarifying this confused anyone.
CFM isn't really a good unit to use for power estimation because it doesn't consider normal changes in air density, which affect the number of O2 molecules per CF. This is why we can't just say a given lb/min = a certain CFM, unless we give a temp, humdity, and elevation. This is why compressor maps give lb/min.
1 CFM = 0.075lb/min at 70 deg F, 50% humidity, and at sea level.
- If the temp rises, lb/min drops
- If the humidity rises, lb/min drops
- If we go up in altitude, lb/min drops
Nevertheless, the 20G should come close to 700cfm at choke flow. I'm pretty certain choke flow falls outside the efficiency zone, so you'll stop making power before the turbo reaches that figure. When I quoted a GT35R as flowing 780cfm, that would be around the limit of it's efficiency, not it's choke flow (which should be somewhat higher). We can't really compare the choke flow of one turbo to the efficiency limit of another. That isn't comparing apples to apples, so sorry if not clarifying this confused anyone.
Jan 11, 2006, 06:24 PM
#769
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So This math class is awesome. But what about 1/4 times and Dynos are people making with this guy. Im Realllyyyyy curious to see what this pulls at the track with a decent driver. How about some feedback from people who have installed it in there cars? Hows it working out?
Jan 12, 2006, 06:12 AM
#771
Track times right now are mostly from my RS. The turbo at 22-23 psi of boost on race gas made 328 whp on our dyno and ran a best of 11.30 and a best MPH of 124 mph.
David Buschur
www.buschurracing.com
David Buschur
www.buschurracing.com
Jan 12, 2006, 06:29 AM
#773
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I'm really considering making like a "Top 10 20G Questions" page.. I keep getting the same questions over and over even though they fairly easy to find already. I'm just afraid even with this people won't read it if I spend time making it 
Jan 12, 2006, 07:00 AM
#777
Originally Posted by EVOONYOASS
I picked up my coated 02 housing today. I am going to start installing this stuff tonight and probably pull an all nighter if my lower back holds up. *now, where did I put those pain pills
In the world? lol
I don't know how relevant this info is but here goes. I also dynoed at the same shop as Charles(ct9a gsr) and on my old tune I put down 373whp and 384trq on C16(26-27psi).
I ran a best of 12.069-12.100 and was trapping 117.8mph. Same trap, but 16whp less and and 36 less torque.
This was with a crappy 1.8-- sixty foot time.
I don't know what was the point you were trying to make smog, but I am making less power and torque and trapping the same, so.......
Originally Posted by Smogrunner
Ok,
On topic. David Buschur just stated in a few posts above that his car went 124mph on 328whp.
Now, go back to post 264:
So now White Rabbits with simple bolt ons are making 364 (regardless of boost) and are therefore capable of around 127mph in the 1/4?
Ok, let's redo the math in a different way:
328wph + 22% = 400whp on Switzer's Dynojet
Now ct9a GSR has one of the fastest stock turboed Evos in the World. He did 389whp/420wtq on Switzers Dyno with 29psi with Alcohol injection:
His top MPH ever is 118.
How is 124mph possible? Things weren't quite adding up so I read a whole bunch of DBs posts over again and found this on post 387:
On some posts Dave posts that it did 120mph and on others he says 124mph. Which is it?
On topic. David Buschur just stated in a few posts above that his car went 124mph on 328whp.
Now, go back to post 264:
So now White Rabbits with simple bolt ons are making 364 (regardless of boost) and are therefore capable of around 127mph in the 1/4?
Ok, let's redo the math in a different way:
328wph + 22% = 400whp on Switzer's Dynojet
Now ct9a GSR has one of the fastest stock turboed Evos in the World. He did 389whp/420wtq on Switzers Dyno with 29psi with Alcohol injection:
His top MPH ever is 118.
How is 124mph possible? Things weren't quite adding up so I read a whole bunch of DBs posts over again and found this on post 387:
On some posts Dave posts that it did 120mph and on others he says 124mph. Which is it?
I don't know how relevant this info is but here goes. I also dynoed at the same shop as Charles(ct9a gsr) and on my old tune I put down 373whp and 384trq on C16(26-27psi).
I ran a best of 12.069-12.100 and was trapping 117.8mph. Same trap, but 16whp less and and 36 less torque.
This was with a crappy 1.8-- sixty foot time.
I don't know what was the point you were trying to make smog, but I am making less power and torque and trapping the same, so.......
I only ran an 11.9, but I know I suck at launching and shifting. If I optimized my setup on the stock turbo I should easily be able to break 120, so I see no reason not to expect >124 from the 20G9 on the properly set up car, especially if there are estimates of it making up to 450-500 whp on a dynojet.
Now, back on topic. David, do you think this would make a good autocross turbo? I need more power than the stocker and I can not have any surging. My stock one surges pretty bad with any BOV other than stock. Power delivery rolling on throttle and easing off throttle needs to be smooth and seamless so as to not upset the car in turns. Have you tried the 20G9 on a 2.3 stroker yet? Do you think we would see full boost under 3000 RPMs in 2nd gear?
EVOlutionary
Jan 12, 2006, 07:13 AM
#778
Originally Posted by Drifto
I found it here http://ztechz.net/id6.html. It may be just a general conversion but I thought you said that a stock turbo, rated at 42lb/min, flows 625cfm and the 3076, rated at 52lb/min, flows 698cfm. It seems to be too small of a difference in cfm for 10lb/min.
Jan 12, 2006, 07:24 AM
#779
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Originally Posted by EVOlutionary
Now, back on topic. David, do you think this would make a good autocross turbo? I need more power than the stocker and I can not have any surging. My stock one surges pretty bad with any BOV other than stock. Power delivery rolling on throttle and easing off throttle needs to be smooth and seamless so as to not upset the car in turns. Have you tried the 20G9 on a 2.3 stroker yet? Do you think we would see full boost under 3000 RPMs in 2nd gear?
EVOlutionary
EVOlutionary
Jan 12, 2006, 07:44 AM
#780
According to the map I have, the stock turbo is approaching the limits of its efficiency right around 38 lb/min, which is a little over 500 cfm at standard temp, altitude, etc. If you can squeeze 42 lb/min out of it, that works out to 560 cfm as per my chart above, which as per my recollection, matches the published specs.
The 52 lb/min of the 3076 equates to ~690 cfm using the same reference.
We can convert those lb/min figures to approximate practical hp limits by doing this:
42 lb/min * 60 min/hr = 2520 lb/hr (air)
Using an AFR of 11.5:1, 2520 lb/hr / 11.5 = 219 lb/hr fuel
219 lb/hr fuel / .55 lb/hr/hp = 398bhp (stock turbo)
We can assume this as a practical limit for the bone stock turbo, which is roughly in line with Dynojet numbers (which are probably more reflective of bhp). Naturally, we know that we can eek another 10% with some effort, but that should be considered more or less a figure used for planning.
If we apply the same calculations to the 52 lb/min of the 3076, we get 493 bhp, which seems realistic.
The 52 lb/min of the 3076 equates to ~690 cfm using the same reference.
We can convert those lb/min figures to approximate practical hp limits by doing this:
42 lb/min * 60 min/hr = 2520 lb/hr (air)
Using an AFR of 11.5:1, 2520 lb/hr / 11.5 = 219 lb/hr fuel
219 lb/hr fuel / .55 lb/hr/hp = 398bhp (stock turbo)
We can assume this as a practical limit for the bone stock turbo, which is roughly in line with Dynojet numbers (which are probably more reflective of bhp). Naturally, we know that we can eek another 10% with some effort, but that should be considered more or less a figure used for planning.
If we apply the same calculations to the 52 lb/min of the 3076, we get 493 bhp, which seems realistic.