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View Full Version : GT28RS 0.64A/R v 0.86A/R?



S13sr95240
03-14-2006, 10:43 AM
I am debating which A/R to get with my GT28RS.
I wonder what's the spool up differences between these two trims. If it is only a couple hundred RPM, then I will get the .86 A/R.

Any dyno charts comparing them?

Any recommendations?

BTW, I searched. Did not find any clear answer.

killjoy
03-14-2006, 11:26 AM
Didn't we figure out that the 2871 is bigger and spools earlier than the RS?

S13sr95240
03-14-2006, 11:59 AM
Didn't we figure out that the 2871 is bigger and spools earlier than the RS?


I have not seen any comparison between them on the same set up yet.

The sportcompactcar dyno of the RS:
1. The turbo is .86 A/R
2. It is on stock exhaust, stock turbo elbow, and high flow cat.

If both turbos are of the same exhaust A/R, then RS will out spools 2871R. But exactly how much I don't know.( I have heard it is about 500rpm).

But, I am not sure how slow 0.86 A/R RS comparing with 0.64 A/R RS. Or will 0.64 A/R 2871 out spools 0.86 A/R RS in the same comfiguration?

Any thoughts?
Did anyone do any comparison dyno?

hernameissilvia
03-14-2006, 12:02 PM
The 2871 is a RS, just with a newly designed comp wheel.

forcefedS13
03-14-2006, 12:09 PM
The GT2871R and the GT28RS are similar but not the same. I did extensive research before ordering my turbo upgrade. The GT28 spools faster than the GT2871, but the GT2871R make more power topend.

I think the GT28 spools about 700 RPM fater the 2871R.

Water
03-14-2006, 12:50 PM
^no way. Both the GT2871r and GT28rs share the same ns111 turbine.

forcefedS13
03-14-2006, 12:56 PM
the GTRS is the infamous disco pitato correct?

If that is so, then why does the disco potato have a limit of 320 hp.

Ive seen the 2871R make more power than that.

Water
03-14-2006, 12:59 PM
No, a gt28rs = disco potato.

Gt28rs does not = gtrs.

forcefedS13
03-14-2006, 01:02 PM
im confused...

a GT28RS= disco potato
a GT28RS does NOT equal a disco potato?????

Water
03-14-2006, 01:03 PM
Sorry, forgot to mention, the Garrett equivalent to a GT-RS (HKS turbo) is a GT2871r w/ the 52 trim compressor.
http://forums.freshalloy.com/ubbthreads/showflat.php?Cat=&Board=UBB9&Number=68074367&Forum =UBB9&Words=gt2871r&Match=Entire%20Phrase&Searchpa ge=0&Limit=25&Old=1month&Main=68066142&Search=true #Post68074367

forcefedS13
03-14-2006, 01:04 PM
http://photobucket.com/albums/f282/bateman240/?action=view&current=10459f04.jpg

this IS NOT a GTRS correct?

forcefedS13
03-14-2006, 01:06 PM
Yeah, they are not the same thing....close...but no cigar.

Water
03-14-2006, 01:06 PM
im confused...

a GT28RS= disco potato
a GT28RS does NOT equal a disco potato?????



Reread my post slowly.

GT-RS (i typed gtrs without the hyphen b/c you did) is NOT a GT28rs. A GT28rs is also called a disco potato.

forcefedS13
03-14-2006, 01:15 PM
i got the two mixed up.

Either way though...for arguements sake...they are not the same. (The GT28RS and the GT2871R.)
GT28RS:
http://forums.freshalloy.com/ubbthreads/showflat.php?Cat=&Board=UBB9&Number=68074367&Forum =UBB9&Words=gt2871r&Match=Entire%20Phrase&Searchpa ge=0&Limit=25&Old=1month&Main=68066142&Search=true #Post68074367


GT2871R:
http://photobucket.com/albums/f282/bateman240/?action=view&current=5b0e675f.jpg


The picture shows some difference alone

SixSpeedSleuth
03-14-2006, 01:22 PM
I am debating which A/R to get with my GT28RS.
I wonder what's the spool up differences between these two trims. If it is only a couple hundred RPM, then I will get the .86 A/R.

Any dyno charts comparing them?



Any recommendations?

BTW, I searched. Did not find any clear answer.



If I were you, I would just get the GT2871R .64 trim instead of the GT28-RS. I started with the Disco on my S13, but sold it and got the GT2871R. I should have just got that one first it would have saved me a lot of hassle. Also the GT2871R spools FASTER than the GT-28RS. Don't let the magazines fool you. Plus the 2871R has much more topend pull.

forcefedS13
03-14-2006, 01:28 PM
EXACTLY

I just got mine...they are different..although i never knew the 2871R spooled faster. Guess i believed the hype.

killjoy
03-14-2006, 01:35 PM
I am debating which A/R to get with my GT28RS.
I wonder what's the spool up differences between these two trims. If it is only a couple hundred RPM, then I will get the .86 A/R.

Any dyno charts comparing them?



Any recommendations?

BTW, I searched. Did not find any clear answer.



If I were you, I would just get the GT2871R .64 trim instead of the GT28-RS. I started with the Disco on my S13, but sold it and got the GT2871R. I should have just got that one first it would have saved me a lot of hassle. Also the GT2871R spools FASTER than the GT-28RS. Don't let the magazines fool you. Plus the 2871R has much more topend pull.




Thats why I said what I did. I was pretty sure that was right.

forcefedS13
03-14-2006, 01:43 PM
Now i feel like a [censored] for arguing so much, but i was sure i was right.

SixSpeedSleuth
03-14-2006, 01:58 PM
Now i feel like a [censored] for arguing so much, but i was sure i was right.



Hell man, it's okay. Thats how you learn. I learned the hard way. I had to buy both turbo's to get what I wanted in the long run. People tried to tell me to buy the GT2871R over the Disco the first time, but I was caught up in the magazine hype. But, I would def go with the 2871R .64 trim. AWESOME street turbo.

forcefedS13
03-14-2006, 02:02 PM
i have the same turbo, cant wait to install it.

im building the head as we speak. Wish me luck.

S13sr95240
03-14-2006, 03:06 PM
Now i feel like a [censored] for arguing so much, but i was sure i was right.



Hell man, it's okay. Thats how you learn. I learned the hard way. I had to buy both turbo's to get what I wanted in the long run. People tried to tell me to buy the GT2871R over the Disco the first time, but I was caught up in the magazine hype. But, I would def go with the 2871R .64 trim. AWESOME street turbo.



I guess what you are saying:
the .86 A/R GT28RS spools slower than the .64 A/R GT2871R and 2871 makes more top end power, correct?

I believe that.

Then, how is 0.64 A/R GT28RS comparing to 0.64 GT2871R?
Anyone?

BTW, I am trying to get a GT28RS is because I can have a very good deal on it and I prefer a faster spool turbo (If it is).

killjoy
03-14-2006, 03:23 PM
I bet the power you will gain with the 2871 .64 would be worth the minor if any spool difference at the same boost.

forcefedS13
03-14-2006, 04:01 PM
If the GTRS spools slower than the 2871R .64 its probably because it is the larger housing of the two. I am willing to bet side by side the .86 GTRS and .86 2871R would spool relatively at the same time, but the 2871R would make more power.

Same goes for the .64 on both. The 2871R would make more power where the GTRS would fall off.

Looking at the thread about the new GTRS, it says they are similar but not the same.

I am going to search and see if i can find dyno results on both turbos with similar AR housings.

SixSpeedSleuth
03-14-2006, 04:24 PM
Now i feel like a [censored] for arguing so much, but i was sure i was right.



Hell man, it's okay. Thats how you learn. I learned the hard way. I had to buy both turbo's to get what I wanted in the long run. People tried to tell me to buy the GT2871R over the Disco the first time, but I was caught up in the magazine hype. But, I would def go with the 2871R .64 trim. AWESOME street turbo.



I guess what you are saying:
the .86 A/R GT28RS spools slower than the .64 A/R GT2871R and 2871 makes more top end power, correct?

I believe that.

Then, how is 0.64 A/R GT28RS comparing to 0.64 GT2871R?
Anyone?

BTW, I am trying to get a GT28RS is because I can have a very good deal on it and I prefer a faster spool turbo (If it is).











Close. What I'm saying is the if both turbos are the .64 trim. The GT2871R spools faster than the GT28RS. I've had both, both the same .64 trim, and the 2871R makes more top end power and spools slightly faster. The 28RS "hits" a little harder at first, but falls off a lot faster than 2871R. I would DEF go with the 2871R. It has a lot more potential.

forcefedS13
03-14-2006, 04:38 PM
THANK YOU sixspeed....that is exactly why i bought the GT2871R .64...........streetability, cost efficiency, potential.

S13sr95240
03-14-2006, 04:48 PM
Now i feel like a [censored] for arguing so much, but i was sure i was right.



Hell man, it's okay. Thats how you learn. I learned the hard way. I had to buy both turbo's to get what I wanted in the long run. People tried to tell me to buy the GT2871R over the Disco the first time, but I was caught up in the magazine hype. But, I would def go with the 2871R .64 trim. AWESOME street turbo.



I guess what you are saying:
the .86 A/R GT28RS spools slower than the .64 A/R GT2871R and 2871 makes more top end power, correct?

I believe that.

Then, how is 0.64 A/R GT28RS comparing to 0.64 GT2871R?
Anyone?

BTW, I am trying to get a GT28RS is because I can have a very good deal on it and I prefer a faster spool turbo (If it is).











Close. What I'm saying is the if both turbos are the .64 trim. The GT2871R spools faster than the GT28RS. I've had both, both the same .64 trim, and the 2871R makes more top end power and spools slightly faster. The 28RS "hits" a little harder at first, but falls off a lot faster than 2871R. I would DEF go with the 2871R. It has a lot more potential.




Sounds like the GT2871R with .64 A/R is the way to go.
One more question:

Which Compressor trim to get:
1. 48Trim
2. 52Trim
3. 56Trim ?

forcefedS13
03-14-2006, 05:05 PM
Im running the T2 flanged 2871R so i can keep my tubular bottom mount. (peak performance)

id say based on your specific goals 52 or 56 would be the right one.

Water
03-15-2006, 07:58 AM
GT28rs & GT2871r have the same turbines so spool is almost identical. According to these dynos though, the GT28rs spools faster (BARELY) until the superior 2871r takes over (before 4.5k). Splitting hairs though IMO. For all intents and purposes, spool is the same.

Both stock everything, Enthalpy tunes.
GT28rs .86 ar - 18psi
http://web.tampabay.rr.com/enthalpy/dynos/sr-gt28rs-86-18psi.jpg
GT2871rs .86 ar - 19psi
http://web.tampabay.rr.com/enthalpy/dynos/sr-gt2871r-86-19psi.JPG

http://forums.freshalloy.com/images/graemlins/beatdeadhorse5.gif

forcefedS13
03-15-2006, 08:23 AM
LOL, in other words the GT2871R is better. http://forums.freshalloy.com/images/graemlins/grin.gif

Water
03-15-2006, 08:24 AM
Yes! http://forums.freshalloy.com/images/graemlins/star-wars-smiley-009.gif

killjoy
03-15-2006, 10:58 AM
GT28rs & GT2871r have the same turbines so spool is almost identical.



Don't always assume that since 2 turbos have the same turbine wheel they spool the same.

Water
03-15-2006, 11:24 AM
I don't. I wouldn't be curious as to how my turbo (3071r) compares to a 30r (spool, both w/ .63 ar).

But if they're similar in size, have the same housings, bearings, ect; they should spool similar - as is the case w/ this thread.

S13sr95240
03-15-2006, 11:58 AM
GT28rs & GT2871r have the same turbines so spool is almost identical. According to these dynos though, the GT28rs spools faster (BARELY) until the superior 2871r takes over (before 4.5k). Splitting hairs though IMO. For all intents and purposes, spool is the same.

Both stock everything, Enthalpy tunes.
GT28rs .86 ar - 18psi
http://web.tampabay.rr.com/enthalpy/dynos/sr-gt28rs-86-18psi.jpg
GT2871rs .86 ar - 19psi
http://web.tampabay.rr.com/enthalpy/dynos/sr-gt2871r-86-19psi.JPG

http://forums.freshalloy.com/images/graemlins/beatdeadhorse5.gif



By analyzing the dyno, I noticed before 4500rpm, the GT28RS
produce the same amount of Toque up to 400 ~ 500rpm earlier than the GT2871R.But that is with the same .86 A/R.


So, I guess the GT2871R .64 A/R should be very close to GT28RS .86 A/R regarding spool up time. Since the GT2871R .64A/R has more topend, therefore it is a better turbo.

240_kid
03-15-2006, 12:21 PM
Can someone post the Pics of The enthalpy Dyno sheets?

Says not found for me http://forums.freshalloy.com/images/graemlins/frown.gif

Water
03-15-2006, 01:42 PM
Copy and paste, they'll work.

240_kid
03-15-2006, 05:38 PM
Thank you very much http://forums.freshalloy.com/images/graemlins/laugh.gif

In_DET
03-15-2006, 09:49 PM
The Enthalpy dyno of the .86 GT28RS is my car. That turbo seized for some reason and I replaced it with the .86 GT2871R but haven't had a chance to redyno it. The GT2871R doesn't spool faster, mine actually seems to reach peak boost (18psi) at closer to 4800 than the 4600 the GT28RS was getting me, but the car definately pulls harder once it does hit peak boost. There is definately less tq with the 2871R and its obvious. With the same enthalpy tune, and just the 2871R instead of the 28rs the car is less prone to smoke the tires when shifting from 2nd-3rd and the tranny doesn't seem to hate me quite as much. With the 28rs hard shifting from 2nd-3rd would leave me spinning my tires for a second and the trans would make a horrible grinding noise. Now the tires spin just a little and the trans just maintains its normal bad synco grind.

S13sr95240
03-16-2006, 10:36 AM
The Enthalpy dyno of the .86 GT28RS is my car. That turbo seized for some reason and I replaced it with the .86 GT2871R but haven't had a chance to redyno it. The GT2871R doesn't spool faster, mine actually seems to reach peak boost (18psi) at closer to 4800 than the 4600 the GT28RS was getting me, but the car definately pulls harder once it does hit peak boost. There is definately less tq with the 2871R and its obvious. With the same enthalpy tune, and just the 2871R instead of the 28rs the car is less prone to smoke the tires when shifting from 2nd-3rd and the tranny doesn't seem to hate me quite as much. With the 28rs hard shifting from 2nd-3rd would leave me spinning my tires for a second and the trans would make a horrible grinding noise. Now the tires spin just a little and the trans just maintains its normal bad synco grind.



So, the GT28RS does have more low end touque with the same A/R then.

Go dyno your car. I just can't wait to see the comparison between those turbos on the same car.

Thanks for the input!