Unsure if I should keep 2560 or go to a 2871 - Page 4 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 06-09-2011, 09:52 AM   #61
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Quote:
Originally Posted by hustler View Post
Shift what he said about boost threshold 800rpm lower, with a bit more torque under there, then less output up top.
I know that FM and others don't favor the disco. Is the FM dyno showing much less spool and little top end gain what people are getting on the street? I see that not every one likes disco and say to skip past it? Isn't it the next incremental step after a 2560?
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Old 06-09-2011, 02:27 PM   #62
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Originally Posted by Landrew View Post
Have you driven a "disco" and care to add any words about that ?
I've driven a couple of 2860RS cars. One forged 1.9 liter with an .86 disco, and one forged FM 1.6 liter with an .86 disco. Both on BEGi cast manifolds/DPs.

The 1.9 liter was the first "big turbo" car I'd ever driven. I road-tuned the car with the owner driving, but I did drive it a little at the end. We did a lot of 2000-7000rpm pulls, and it was much smoother than I was expecting it to be (compared to my 2554). The 2871 gives up a tiny bit of response (definitely not 800rpm worth of onset, more like 200-300rpm) in exchange for 75whp worth of top end, which is worth it IMO.

The 1.6 was a lot laggier and a lot less responsive. Whereas the 1.9 liter 2860RS feels like it comes onto the torque band between 3500 and 3800rpm, the 1.6 car was delayed until the ~4200-4500 range. In comparison, a 1.6 liter 2560 car feels like it's on power at around ~3200-3500.

The 2871 will respond a couple hundred RPM slower than a 2860RS, but I think a 1.9 liter 2871 has faster boost response than a 1.6 liter 2860RS (assuming .86 hotsides on both cars) - hopefully that gives you an idea of the difference.

From best response/onset to worst response/onset (response = how closely boost follows throttle inputs, onset = how smoothly a setup transitions into its torque band)

1.8L 2554R .64
1.6L 2560R .64
1.9L 2860RS .86
1.9L 2871R .86
1.6L 2860RS .86
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Old 06-09-2011, 02:41 PM   #63
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Great thanks again.

Funny the 2871 I was trying to buy is actually a Disco. I asked for the Garrett ID tag and when I ran the numbers I told him thats a disco not a 2871. Still trying to pester him to get it but he's 3 hours away. I've had a few deals fall through - thats the price of going used I guess, oh and being cheap!
My issue is availability right now, I'm getting so tired of running my slow boosting 2560 that I'll take whatever I can from a 2560-2871 and I'm sure I'll be happy.

These reviews make me feel comfortable that with my VVT car I'll still find fun in every turbo, thought I'm thinking bigger than the 2560 is where I'd like to end up.
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Old 06-09-2011, 05:13 PM   #64
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Hmm the part number he gave me has the .64 A/R housing option. On the disco with the .64 isnt that going to place it right at the 2560R levels ?

Doesn't the .86 really define what a Disco means to people ? The .64 makes it pretty much a 2860R ?? Garrett has models all over the place!
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Old 06-09-2011, 05:21 PM   #65
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There is some old debate on .64 vs .86 spool vs power.
But you just said you'd settle for 2560-3072 so you should be happy
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Old 06-09-2011, 05:23 PM   #66
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I think it will match a stock block well and then there is the option of going to the .86 or 2871 with a built engine later on.
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Old 06-09-2011, 07:43 PM   #67
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Landrew, I'm interested in a 0.64 GT2860RS.
Could you forward to me his info?
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Old 06-09-2011, 07:46 PM   #68
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I got a 2871 with .63 A/R for now (it's T25 inlet, v band outlet).... when motor gets built to make power in higher rpm, I may end up switching to a larger A/R
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Old 06-10-2011, 03:52 PM   #69
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Originally Posted by JasonC SBB View Post
Landrew, I'm interested in a 0.64 GT2860RS.
Could you forward to me his info?
No because I am buying it.

But I did almost get this 2871 and it's still going for $551:

http://cgi.ebay.com/ebaymotors/Garre...item45fb07ed69


It says remanufacturered which to ebay means - " It is the functional equivalent of a new part and is virtually indistinguishable from a new part. " Though when I asked him he said the CHRA has a few thousand miles on it. Seemed odd but otherwise his sales seem quite legit and he has a lot or turbos for sale
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Old 06-19-2011, 02:00 AM   #70
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Originally Posted by y8s View Post
If you're planning to use your VVT, then the 2871 is probably the smallest turbo you'd ever want. I'm using a 2876 and I have no complaints about lag based on where I find myself in the power band. If I'm above 3k, it pulls nicely until it pulls like mad.
Do you mind telling me a bit more about your 2876, what model number is yours/what A/R? Are you still enjoying the way it drives after running it for so long, did you have any thoughts on going smaller? Is VVT one of the key drivers of it's nice spool? Also tell me about the lambs Clarice......

Thanks

Last edited by Landrew; 06-19-2011 at 03:21 AM.
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Old 06-19-2011, 02:38 AM   #71
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Nice silent of the lambs quote out of the blue.

Yes VVT helps spool.
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Old 06-19-2011, 11:58 AM   #72
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Quote:
Originally Posted by Landrew View Post
Do you mind telling me a bit more about your 2876, what model number is yours/what A/R? Are you still enjoying the way it drives after running it for so long, did you have any thoughts on going smaller? Is VVT one of the key drivers of it's nice spool? Also tell me about the lambs Clarice......

Thanks
I have a stock motor and for a while was planning to build it but then sold off all the parts. Then I thought about smaller turbos when I wasn't going to build the motor--but nothing smaller than maybe a 25 or 2860. In theory, a 2860 would bolt up to my exhaust housing and only require changing the compressor inlet and outlet diameters. 9-10 psi seems like a waste for a large turbo like the 2876 sometimes.

BUT

With the boost control mostly tuned and the VVT mostly tuned, if I punch it at 3150 in 5th gear, I get full boost (7 psi) by 3600 rpm. And looking at this datalog... I wasn't at 100% TPS the whole time.

The larger turbo does keep me out of boost for normal driving which saves gas on a street car. I dont have to deal with part throttle full boost most of the time.

How does it drive? Basically if I'm above 3500, it pulls like a train in any gear. In 2nd gear, flooring will break my 225 RS2s loose.

So yeah I like it. But I'd still probably go for a 2871 with the 4 inch inlet if I were to do it again. Why? Because a 2871 spools faster and has headroom for 350 hp.

I have the .64 A/R turbine housing. There are only two model numbers and turbine A/R is the single difference between them. You could probably even find a used turbine housing in the other A/R if you're unsure what you want. Swap and see and sell the spare. Hustler and Savington like the .86 on their turbos. They track their cars. I like the .64 and I don't track mine. I don't remember seeing a dyno plot to show a same-setup comparison between turbine housings but they are convinced the .86 doesn't reduce spool much and has better top end.
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Old 06-20-2011, 12:34 PM   #73
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Great thanks for the ride report. That sounds a touch large for my goals, but it is quite nice to see how much VVT helps out.
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Old 06-20-2011, 03:00 PM   #74
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I second all this. I went from a 2560 to a 2871. I don't miss the difference in spool times on the track or even the street. 15psi on the 2560 felt like 10psi on my 2871. I still haven't had the desire to go past 10psi yet. I haven't even once questioned what it would be like if I had the the smaller 0.64 turbine housing.

I have an ARTech manifold, so I have no idea how things would change on a log style manifold.

Quote:
Originally Posted by Savington View Post
The 2871 is a larger turbo, and it drives like it. Boost response isn't quite as good, there's a little more lag, and it comes on a bit less smoothly. When it comes on, though, it pulls like a god damn freight train, all the way into the rev limiter. The 2560 will start to run out of breath past 6500rpm, but the 2871 is still pulling hard at 7k.
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Old 06-20-2011, 03:07 PM   #75
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Very nice.

Theres a 2876R .64 A/R local for a decent price, just not sure I want that delay on the street, though lately street has meant cruising at 80km hr all the time. No stop light driving so I'm already moving air - hmmmmmm


My other worry about a 2871 or 76 is that I would be using the internal WG. Won't that be a big issue for creep on these larger turbo's ??
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Old 06-20-2011, 03:26 PM   #76
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I welded up the internal gate and have been running a TiAL 38 since day one.
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Old 06-20-2011, 03:36 PM   #77
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Yes I know you and dgmorr are running EX WG so my results will vary. I dont want any creep with a big old 287X turbo and a stock 02 block - boom! Isn't creep anplified on these 28 series ?


Cake and eat it too: maybe be next year.....

Hearing that you guys are running the big 287X on your stock VVT motors is very enticing, just that my log manifold and internal WG wont quite spool like you 2 and that spool time is a big factor in going to a 28 series. Youve paved the way just that I'm not too confident in my current setup handling it....
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