Turbo size selection
 

Ok so I don't want to spill the beans as its early on in the project, but let's just "pretend" that someone built a motor out to nearly 2.0L, and is trying to decide which snail to upgrade his gt2560 to.....

I initially was just going to just keep the 2560, then decided I was going to follow Levnubhin's suit (peer pressure) and upgrade to more power without having to invest much seeing his success with the China2871.

I had a couple hours downtime at work, and started trying to understand those compressor maps, just to make sure it'd be a good fit (Levs = 1.6L).

IF I'm understanding some of what I read, and IF I did the math right, and IF I'm reading the comp map right (lots of if's I know...)--it seems that I (and prob others) could easily go with a larger turbo without sacrificing much if any in spool.

Tell me, how far off I am...correct me....etc.. I'm sure Joe or the like can step in here and enlighten me in lay man's terms...

Bellow are 2 maps I plotted using the formulas provided in the Garrett 103 info section off their site. My understanding is:

3076 is the choice for my setup
-3 power goals are well within efficiency range
-I have headroom should I require more boost, flow isn't ideal, etc..to make power goal. (The plots seem to pattern in the same direction as the efficiency range)

What I been trying to understand is either my plots, math, theory is all wrong...OR the higher range of the map (3+bar) is for a power goal/displacement which is not compatible with our cars. On every single map I did (2554 - 3582), my plots never came close to the top of the comp chart. Other than this I'm thinking my numbers look OK, maybe not exact or ideal, but at least to say I'm making a SEMI-calculated decision???

With a 2.0L I'll get a Holset hx35 and smash mad bitches!!

50 views?? Me thinks my title makes me sound like another PITA newb looking for which turboz goz da fastez....

I was fully expecting the likes of Joe P up in this bitch either knocking some sense into me, correcting my math, or posssssssssssssssssibly an ever so small pat on the back (no homo)

If I had a 2.0l I would look into a Holset HX30-35 turbo. Incredibly reliable and make an ass load of power.

Hey at least you are trying. But, though it is a good exercise to figure it out by hand at least a few times, here is a great online tool for checking turbo maps and playing around with what-ifs.

http://www.squirrelpf.com/turbocalc/

You may have to read up a bit to get all the inputs right but it will plot the map for you. They also have lots, no gobs of Garret turbos already loaded in their site, including all the ones that one would run in a Miata. I used this tool when I was picking my current turbo. Check your map plots based on your assumptions against the turbocalc generated ones.

FYI it seems to be acting strange in Chrome but works fine in Explorer.

Hey that's a great site. I already found there's an issue in my Pressure Ratio calc seeing as how my graphs are linear and there's aren't which makes more sense.

Gonna figure out where it is and replot maps to compare and see what the new results are

Holset smashes mad bitches

I hear ya, I'm just trying to understand the garrett stuff since all the info is there, then I can consider other manuf's

gt2871 or 2876 for the big 2.0.

I agree with that. The 2871 works well on my 1.8L so would certainly be fine on a 2.0L

thats what got me interested in these maps actually. phil is running a china 2871 on his 1.6, so it made me wonder if i was leaving something on the table

not going for huuuge hp, but ould like to make it with lower psi than him

If you look at the compressor and turbine measurements on some of the china 3076s they are smaller than a Garrett 3076. Be sure to double check what you are buying when the time comes. Two different ones I just looked at that were listed as gt3076r spec'd out as 2873s (if there was officially such a size). Both were Godspeeds and they had very slight differences in turbine inducer diameter, but not enough to bump them up to a different size class. The real Garrett gt30xx has a 60mm turbine inducer and the Garrett gt28xx has a 53.8mm inducer. The ebay Godspeed gt3076r turbos had 53.8mm and 54.5mm turbines if you believe the posted measurements.

IMO if you are running anything near or above 300BHP you are better off with at least the 2871 for the improved efficiency. You can get there with a 2560 (Brain did it IIRC) but it is going to be much less efficient than the 2871. That means, as you probably know, more PSI and hotter IATs, all else being equal.

The only reason to get the 2560 is if you HAVE to have the improved spool, not just RPM, but transient also. That being said I daily drive my 2871 car and the spool does not suck at all. I do have a tubular manifold and a full Enthuza 3" exhaust which really helps. Check out the spool thread if you have not read it already. Lots of good information there.

Thanks guys appreciating the info.

FYI when I mentioned Phil using the 2871 on a 1.6, I meant I was wondering if I shouldn't go even bigger considering. The 2560 is going regardless, love it to death, but it's going to choke. My comment was referring to taking it up to a BIGGER turbo than the 2871 Phil has, ala 3071/76. I know how Phil is doing and no doubt in mind mind I will runa 2871 if not the 30xx series.

I say 3071

Plus, with a T3 flange, if you ever fuck your turbo up, you can always throw a $200 ebay turbo on there temporarily while the GT is being rebuilt.

^this will be a China turbo to begin with, I was just on the Garett site for the 411

Well then go T3

Yeah no worries. Figured you were going big.

Just a thought since Holsets are in the mix too. The BW stuff is very interesting to me. I dont know exactly what your goals are, but an S258 would flow enough air for well past 300WHP with boost in the 20s or so and 80% efficiency, which is pretty badass.