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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 08-13-2007, 10:33 AM   #21
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Talk to Stripes, he used to run a GT2554R and now has a potato on his car, he could give you an actual comparison of the two turbos on the same car. FWIW, last I talked to him, he LOVED the potato compared to the 2554.
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Old 08-13-2007, 10:45 AM   #22
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Unforutnatly, I think stripes in on vaca, if you talk to him let me know if hes around or checks the boards. I would really appreciate his input.
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Old 08-13-2007, 10:54 AM   #23
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but looking at those two turbo maps, im not seeing a whole lot of advantage of the GT2860RS. It seems to spool earlier and well top end wont be an issue with either of these turbos.
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Old 08-13-2007, 11:02 AM   #24
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I agree the potato is more for top end, but I remember him saying that he liked the power delivery of the potato b/c the 2554 ran out of steam high end where as the potato pushed hard to redline. Actually, if 250 is "really" your goal (like it ever ends), I agree with other peeps that 2560 and T3 are probably the better option.

Also, if 250 is really your goal, the 2554 is really stretching it and as you said blowing a lot of hot air. Just for reference, kags old setup with built engine (9:1 pistons) and the better flowing 99 head made ~210-220 at 12-14-ish psi IIRC. I'm not saying that you can't get 250 with the 2554, but it's really stretching the limits of the turbo and you need a pretty efficient setup with minimal IC pressure drop, etc....
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Old 08-13-2007, 11:05 AM   #25
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Now i just have to figure if I want a china charger or not
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Old 08-13-2007, 12:17 PM   #26
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Didn't Jason C make 240 at like 9 psi with a 2554? I'd sure like to see all these turbos on the same dyno.

Frank
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Old 08-13-2007, 12:33 PM   #27
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Quote:
Originally Posted by fmowry View Post
Didn't Jason C make 240 at like 9 psi with a 2554? I'd sure like to see all these turbos on the same dyno.

Frank
I believe he did say 240hp @ 10psi on a 99 engine (9.5:1 compression vs. 9:1 compression for NA 1.8), AVO manifold, and a damn good tune. I think stripes made ~220hp at 12-14psi which is more in line with what I have seen elsewhere. Add in a few percent of variablility between dynos and I think they are all in the same ~220 ballpark. Not saying that 250 is not possible, but you are asking a lot of the turbo at that point and blowing a lot of hot air.
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Old 08-13-2007, 01:33 PM   #28
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I'm checking the boards, I'm just very medicated at the moment Yes, I ran a gt2554r and recently switched to the potato. First of all, I really liked the gt25r. It was a blast to drive and put out plenty of power. I think I dyno'd 11psi at around 214hp. I feel if I had time to tune and knew what I was doing, I could have reached 240hp with the gt25r. I came to a cross road with these compression maps just like everyone else. On paper and through these calculations, all of the turbos mentioned above have good characteristics and overlap in your hp goal is some way. For me, I came across a good deal on a potato and decided to try a real world comparison. Most of my findings and results were expected. The potato had more top end power compared to the gt2554r bottom end grunt. Both turbos are fast spooling and fit the miata well in my opinion. It came down to a personal preference and I decided to go with the gt28rs for three reasons:

1) I liked how the gt28rs pulled all with way through the rpm range. I'm willing to sacrifice a little low end torque for more top end power.
2) I can grow with the gt28rs. If I ever decide to build a motor, 300 is within reach with a potato.
3) The gt28rs just feels right. It doesn't feel like it's trying too hard to make hp and it is very drivable. I'm sure there are better turbos for the miata, but I don't have the time or money to test all of them. I guess if I could sum my experience up in one sentence it would be go bigger or go home Instant spool is overrated.

Hopefully I'll hit the dyno soon and get you guys some numbers.

I'm tired...going back to bed.

-john
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Old 08-13-2007, 01:35 PM   #29
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Well said stripes
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Old 08-13-2007, 01:42 PM   #30
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Quote:
Originally Posted by Braineack View Post
I dont care how much a goddamn turbo hweel can output....it doesn't matter.

if 340BHP Requires 37.3 lb/min or 539.71 CFM or X kg/s or X m3/s, you cant change the fact.

the only way to read a compressor map is first determining the amount of volume flow it takes to reach a certain power level, and then determining the amount of boost it will take to reach that amount of voulme per RPM. So you can plot that RPM point on the graph....it's the only way you can do it.

You cant simply say, oh hey my turbo flow X at it's best, so therefore I'll make 700rwhp at 2psi. It's not the way it works.

and lb/min is not misleading, nor is CFM (they are the same damn thing)....it's why the goddamn compressor map has an axis for the volume flow, because it's required to plot against the map.



yes, you can reach over 100% VE, however for the calcs, it's screws up the math completely. Use 100% if anything.

if it's taking these mx3 owners 20psi to reach 200rwhp, then they either have a potato clogging the tailpipe, or are simply using a turbo that's too small.

Not because a small turbo produces less power than the large one, but the small turbo cannot produce enough airflow to support the HP you are asking from it and it's performing well outside the 60% efficiency mark.

Take this chart for example:
http://www.stealth316.com/images/dr-comparo.gif

look at 1.6 DR.

all three turbo will output the same flow at that boost level, where the 9B reaches it's max flow early, the rest of the time the power ouput with the 9B and 15G will be nearly equal.
Name:  tempdifference.jpg
Views: 1
Size:  131.1 KB what a difference temperature makes anyway.
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Old 08-13-2007, 05:39 PM   #31
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Lets hear those opinion boys, and what do you guys think about my future china charger

http://cgi.ebay.com/ebaymotors/GT28R...QQcmdZViewItem
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Old 08-13-2007, 06:31 PM   #32
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This is a good comparison of how the 2560 and 28RS stack up together.

http://flyinmiata.com/tech/dyno_runs/Jeremy_potato.pdf

IMHO, unless you're shooting for high HP, it's a big scarifice in low-end.

What's your goal, btw?



Last edited by Braineack; 08-13-2007 at 06:42 PM.
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Old 08-13-2007, 06:36 PM   #33
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Internal gate set for 12-17 psi? You want it below what you want to run, so how much boost do you want to run?

Personally I wouldn't pay $400 for a chinacharger. The biggest grip on the chinachargers is the tolerances. Ballbearings just leave that much more room for error.

Frank
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Old 08-13-2007, 06:41 PM   #34
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250 is where i would like to be, but im used to driving my friends FMII car at 10PSI and I know ill want more than that.

The wastegate, i have a 6-10psi one playing around, and im going to go to ebc eventually

Im thinking the hit for the topend and cheapness is worth, along with the room to grow

Last edited by Loki047; 08-13-2007 at 06:55 PM.
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Old 08-13-2007, 08:02 PM   #35
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the 50 trim just isnt large enough to support the power.

Try the chinacharger....if you dont like, look for a real used 2560 or 28RS or 2871 or something

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Old 08-13-2007, 08:13 PM   #36
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will those all work with the manifold and dp setup
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Old 08-13-2007, 08:44 PM   #37
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Depends on if you get the standard 5 bolt flange on your turbine housings. Are you gonna go internally gated?
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Old 08-13-2007, 09:12 PM   #38
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yes.
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Old 08-13-2007, 11:11 PM   #39
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Quote:
Originally Posted by Loki047 View Post
will those all work with the manifold and dp setup
physically, they should all be the exact same.
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