Honda D Series Forum banner

1 - 20 of 26 Posts

·
Registered
Joined
·
375 Posts
Discussion Starter #1
Hey guys. I need help

Im running a gt2860r and i already maxed it out.

so im thinking to go to a gt2871r.
only thing is that i talked with a friend of mine that works for store that sells turbos and he can sell me a gt3071r t3 with the antisurge(like the gt3076r) for the same price with the gt2871r.

The thing now is that both turbos are similar in hp numbers.
I want somewhere of the 400hp mark with the least turbo lag.

so im posting the maps that garrett gives.
Please let me know which one is better.




 

·
Registered
Joined
·
764 Posts
The gt3071r. The spool may be a bit slower but its a much better turbo. The gt2871r its somewhat choked by the smaller turbine. Go with .63 as well.

Also you will be flirting with safe max for the gt3071 at 400hp. I have never seen 400HP with the gt2871r.

There are other options that are actually just as good that will cost less unless you are getting a killer deal on the turbo.
 

·
Registered
Joined
·
253 Posts
The gt3071r. The spool may be a bit slower but its a much better turbo. The gt2871r its somewhat choked by the smaller turbine. Go with .63 as well.

Also you will be flirting with safe max for the gt3071 at 400hp. I have never seen 400HP with the gt2871r.

There are other options that are actually just as good that will cost less unless you are getting a killer deal on the turbo.
listen to this man ^^^^

exactly what i was going to say.
 

·
()*#$(*$
93 Legend L Coupe.
Joined
·
11,404 Posts
The gt3071r. The spool may be a bit slower but its a much better turbo. The gt2871r its somewhat choked by the smaller turbine. Go with .63 as well.

Also you will be flirting with safe max for the gt3071 at 400hp. I have never seen 400HP with the gt2871r.

There are other options that are actually just as good that will cost less unless you are getting a killer deal on the turbo.
I am curious as to why you say the 3071 is a better turbo, as I was contemplating using a 2871 for a long while.
 

·
Registered
Joined
·
764 Posts
The biggest mistake people make when they chose a turbo is that they look at the comp map and then go with the smallest turbine and AR for spool. You have to understand that the turbo works by using the flow created on the comp side and converts it to pressure by using the turbine nozzle. The turbine works by converting heat pressure into mechanical energy. Its the psi of the exhaust pre turbine turbine that is flowing to lower psi atmosphere.

Look at the max flow comp flow on each comp map. They are close to 45lb min. Now look at the turbine maps and their efficiency. The gt28 hits peak at 15lb min and the gt30 hits peak at 20lb min. Once you hit peak turbine flow you will get less out per psi from the comp. Basically you start to choke the turbo because the turbine can not keep up.

I have seem the gt2871 and gt3071 both on the same motor and setup first hand and at the same psi. The gt30 spooled slighter slower but made far better peak HP at the same psi.

I'm at work but I can go into this in greater detail later.
 

·
()*#$(*$
93 Legend L Coupe.
Joined
·
11,404 Posts
Ok. That makes sense.

However, ATP releases a twin scroll bolt on turbine housing for the GT28 series. I think that would be fun to play with, as I have not been impressed at all with the spool and response times of the GT30s on D-series engines.
 

·
()*#$(*$
93 Legend L Coupe.
Joined
·
11,404 Posts
Turbine maps are . . . difficult. The only good information I've seen online is the BW AR charts, mostly because they have very specific turbos. Garrett probably has done the work, but since there are eleventy trillion combos, that is a significant investment in testing. I wouldn't want to just give away that info, either. The turbine map is generally a combination of the whole turbo, as the turbine map is effected by the shaft, bearing assembly, compressor, turbine and compressor housings, EGT, etc. All of those variables make things very hard to test consistently or completely, as EVERY combination would be different.

GT28RS/2871R 0.82 A/R T3 DIVIDED Turbine Housing : atpturbo.com

Not cheap, but interesting.
 

·
Registered
Joined
·
764 Posts
Guys the first and fourth picture in the first post are turbine maps.
 

·
Registered
Joined
·
375 Posts
Discussion Starter #16
im curious about what you said for the gt2871r because at turbobygarrett.com says that makes 470hp...

Actually i dont really care about peak numbers.
I want a gt series turbo that will make around 400hp and still spool fast.
My car is a daily driver keep that in mind!
 

·
Registered
Joined
·
375 Posts
Discussion Starter #17
The gt3071r. The spool may be a bit slower but its a much better turbo. The gt2871r its somewhat choked by the smaller turbine. Go with .63 as well.

Also you will be flirting with safe max for the gt3071 at 400hp. I have never seen 400HP with the gt2871r.

There are other options that are actually just as good that will cost less unless you are getting a killer deal on the turbo.

i get both turbos for 700euros...its dirt cheap!!!
 

·
Registered
Joined
·
764 Posts
Right. I know that. They aren't terribly informative, though, unlike the compressor maps.
They are very informative if you understand what they mean. The line moving left to right is efficinecy but it does not show peak efficiency which relates to lb min comp/ lb min at turbine. You actually meet peak efficiency slighter before the peak turbine efficiency. I will get into this in great detail in a bit. Right now I just got home and am going to get a bite and take a knap.

Was up all night watching my "Eers" pound Clemson 70-33......
 
1 - 20 of 26 Posts
Top