Question About Compressor Maps, 20g / B16g

[focusedrage]

The way I understand some things that I have read, is that the best situation would be to have your desired cfm and pressure ration fall in the ellipse of the highest efficiency. Is this true? And does highest efficiency mean that the exiting air temp will be lower?

I ask this because I am trying to decide between Slow Boy’s 2gb16g and 2g20g, however with my current plan I don’t think I will be able to use the 20g to its max… but would a 20g be a better choice because the psi I would be running would fall in a more efficient area of the compressor map?

Then there is spool times to consider, I’m not entirely sure how these two compare in terms of spool, but would it ultimately be a better idea to get the 20g, which has more room for expansion, as well as more efficiency?

 

[ItsStockOfficer]

The 20g makes more power at 14 psi and the difference just gets larger from their. The 16g has some wicked pressure ratios that make it look effcient at high boost on a map, but they don't like flowing over 300 hp worth of air.

 

[ShapeGSX]

I'd get an Evo 16G instead of a big 16G. I've gotten 44.1lbs/min of airflow out of mine at 26psi. It DOES flow a lot of air at high pressures. That got me 118mph trap speeds in my stock weight 2G.

I have a lot of supporting modifications, though. You will need lots of supporting mods to get the most out of any turbo, though.

 

[ItsStockOfficer]

You shape...your our model of what a 16g based car can do, the rest of us have to deal in reality =)

What gas was that on?

 

[ShapeGSX]

Sunoco Supreme NOS. About 117 octane.

 

[Groomz]

Someone on this forum e-mail SBR and asked the difference between the Evo III 16G and the TDO5 20G. SBR told him the performance would be about the same, with the 20G having a little slower spoolup.

 

[ItsStockOfficer]

Thats a complete load of crap.

 

[kpt4321]

Not really. The TDO5H 20g CAN make more power than the EVO 16g, but in reality not a whole lot more. If I was looking to buy a 20g, I would get the TDO6H version.

To the original question: You don't necessarily need it to land in the highest efficiency island, but more importantly you want to see what the efficiency rating is at your desired airflow and boost.

However, efficiency really doesn't make as much of a difference in terms of power as most people think it does.

The TDO5H 20g is going to have less backpressure (more power) because it's clipped (yuck).

I don't understand how you can say the 20g "makes more power at 14 psi." Make more power that what, on what car, with what setup, with what tuning, with what parts.....

 

[ItsStockOfficer]

Originally posted by kpt4321
Not really. The TDO5H 20g CAN make more power than the EVO 16g, but in reality not a whole lot more. If I was looking to buy a 20g, I would get the TDO6H version.

A large turbine to be sure, I would be interested to see what it could do. I ran a TDO6 20g into the 11 for quite a while and it was a strong performer.

To the original question: You don't necessarily need it to land in the highest efficiency island, but more importantly you want to see what the efficiency rating is at your desired airflow and boost.

However, efficiency really doesn't make as much of a difference in terms of power as most people think it does.

Assuming you have a good intercooler, and especially assuming your on a good gas, thats very treue. When I see people argueing that a turbo is better because it peaks at 78 instead of 76% efficieny I can only laugh. However, when you run a 16g like shape into what is probablya 50% effciency range there is no doubt that a larger compressor(and equally larger turbine, but that's not the discussion) could perform significantly better. I doubt he would disagree.

The TDO5H 20g is going to have less backpressure (more power) because it's clipped (yuck).

For what its worth, I think that a larger turbine is a good thing, but clipng has defintely proven to be a very effective method on the Mitsu turbine. I have never actually seen a effciency test done on a mitsu turbine before and after clipping, if you know of one I would like to see it alot. I do know that in terms of power output, My tdo6 clipped 15 degrees, the br20g, a FP20G TDO5 clipped 20 degrees and my friends unclipped TDO6 are all very competitive and similair. They spool within 200 RPM of each other, and its difficult to compare peak power output.

I don't understand how you can say the 20g "makes more power at 14 psi." Make more power that what, on what car, with what setup, with what tuning, with what parts.....

I would say Im refering to a car with basic bolt ons.....mod for mod basically. I know that the first mod on my dsm was a fuel pump, followed by a 20G, the car performed very well. After a 3 inch turbo back, air filter and a fmic made from 2 stock sidemount I welded together it ran [email protected] at 19 psi on race gas. Definitley significantly faster the a similairly modded 16g car.

But even on pump gas vs a 16g at the same boost level (15 psi, at which point I would begin to ful cut) I was quite a bit faster. At 15 psi on pump with the previous mods it ran a 12.9@103 I believe(some of my best driving). This was back in high school. Of course mine was a clipped tdo6 so its not DIRECTLY comparable, but of the many cars around me have the BR20G, and one has a FP 20G with a 20 degree clipped tdo5 turbine, and its extremely competetive.

With some clipping a TDO5 20g has no problem getting into the low 400 whp range, which is pretty much unheard of for a 16g...Pushing the tdo5 20g.....They have gone 10's in numerous cars over the years, and trapped as high as 130 MPH(The BR20G)....certainly not 16g territory.

 

[focusedrage]

you guys' knowlege of turbos is inspiring... thanks for filling me in i think i have decied to get the 2g20g... which is td05, i think it will do whant i want this summer, and have some room in it. also can the td06 be swaped into that turbo latter on?

 

[ItsStockOfficer]

I would HIGHLY recomend not getting that 20g. If your gonna get a SBR turbo get the G50, which is a much much better engineered turbo.

 

[focusedrage]

do other people hold this position?
i was looking at the g50 but its 50 more without a wastegate...

 

[ItsStockOfficer]

My opinion is that the SBR 2g20g has too small a compressor housing for a 20g wheel, and that a 20G require a heavy clip if its TDO5. The cost of a clip s ussually 75 dollars, bringing the costs a bit closer.

However, a much better deal is the AGP RS49 for 825. Same as the SBR50 but I think it has a better turbine housing. Same wheels and compressor housing though.

If you want to IM or email me at [email protected], I can make some more, even more cost effcient, ideas for you.

 

[focusedrage]

i looked at the agp rs49, i think that is the one for me, and i have heard nothign but good things about agp

 

[AWDGrayBird]

if i was you i would just go for a sbr gt12 you can get it in 50 56 or 60 trim internaly or externaly gated there dual ball bearing there just sick they spool pretty quick they are kinda pricey but there awsome my friend has one on his 90 at 18psi and he lit up a 2003 zo6 that are 405hp and he smoked his brand new z rated on 16x7.5 through first and second and thats stock weight and everything there nice as hell but he has the to4e compresser housing 4" inlet http://awdturbo.myserver.org:8080/ here is the web page click on 90 dsm mods you can see what he has but there nice as hell

 

[BoostinAWD]

SBR GT12 = AGP L2R

oh btw you can't go wrong with agp, great customer service. I highly recommend them.

 

[ItsStockOfficer]

Originally posted by AWDGrayBird
if i was you i would just go for a sbr gt12 you can get it in 50 56 or 60 trim internaly or externaly gated there dual ball bearing there just sick they spool pretty quick they are kinda pricey but there awsome my friend has one on his 90 at 18psi and he lit up a 2003 zo6 that are 405hp and he smoked his brand new z rated on 16x7.5 through first and second and thats stock weight and everything there nice as hell but he has the to4e compresser housing 4" inlet http://awdturbo.myserver.org:8080/ here is the web page click on 90 dsm mods you can see what he has but there nice as hell

God damn it! Puncuation! Puncuation!!!!

 

[BoostinAWD]

I've known him for 19 years. He doesn't have any!

Sorry dustin.

 

[Mike 99GSX]

Originally posted by ItsStockOfficer
God damn it! Puncuation! Puncuation!!!!

Punctuation! Punctuation! Spelling God damn it

 

[ItsStockOfficer]