M50TUB28 S256 E85 Dyno

[Nutzy]

they just wouldnt gain anymore. Keep in mind, im talking in pump gas terms and not max effort either. Ill air on the side of caution for most cars, unless its mine, then i usually dump in a bunch of timing and blow it up.

LOL! Fair enough. Ed put some more timing into it and it didn't improve so he scaled it back.

[Nutzy]

A bit of catch can building going on around here.

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- - - Updated - - -

So I was having a bit of a look at some compressor maps today, starting with the map for the S256 on my car. At 2.2PR (18psi) and 55lbs, it is pretty much right at the edge of the map and in the 60% line. Then I took a look at some maps for 65lb compressors such as GTX3576, EFR7670, and S258/9, and to get 65lb out of them at 2.5PR they are once again at the very edge of their maps and in the low 60%. On the other hand, GTX3582 at 65lbs is sitting pretty at around 74% with more to go.

How much does this matter? Of course I know that 10-12% gain in efficiency is better in terms of lower shaft drive power and then lower BP as a consequence, but if 65lbs flow was your target, would one bother with the 3582 and live with the slower spool?

[vollosso]

Those compressor maps are pretty important. Raji didnt believe me when i said he was out of air.

The percentage there is the amount of heat vs the amount of air. A 10% difference is sizeable.

I think the 35r will spool faster, but it depends on what housing you're currently running.


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[wazzu70]

Time to move to an S300sxe platform?

Have you compared with the S257SXE? Billett compressor gots more flow and you should not have to change much else with the setup. Probably still need a new turbine housing due to smaller turbine wheel.

What exhaust A/R do you use?

Map:

[Nutzy]

I was sure I saw some mob offering upgrades of the compressor wheel on the S256 and now I can't find it anywhere. It would be a reasonable option and not very much $$ to get 20% more flow and still have the 65mm exducer turbine as well (S257SX-E is 61mm).

I have an AGP 0.84 turbine housing on their now.

I read an interesting article last night on back to back testing of GTX3076 and GTX3582 on a WRX. They tried 0.63 and 0.82 housings on each turbo and ran dyno testing. The ECU was in charge of closed loop boost control so variability was taken out of the equation. The surprise in this test was that the only thing the larger turbo offered was more lag with the power lines almost dead even. It wasn't until the boost was up to 1.9BAR and the GTX3582 was running the larger 0.82 housing that it made more peak power, but with this housing it gave away as much as 120ftlb in the midrange to the smaller unit. Looking at the turbine/housing maps, the 3582 was choked with the 0.63 at the same flow as the 3076 with the 0.82 which apparently explained the lack of gain.

Interesting stuff and all, but those two turbo's retail for nearly $3000AUD here in Aus! S257 is a steal!

[wazzu70]

Garrett is really good at offering up really expensive units that provide mediocre results lol.

would be interesting if you could put a 57mm inducer FMW wheel and SXE comp cover on the turbine wheel you have.

I have been looking around for results on the S256SX with different turbine housings. Full Race recommends the 1.22 A/R with the T4 TS footprint. Not sure why. The S256 "OG" had like a .88 A/R option as the biggest one. The newer turbos have a .83, 1.00, 1.09, 1.15, and 1.22 A/R option. Not sure why the largest one only is recommended?

Maybe the old S200 and newer S200SX turbos have different volute sizes due to the turbine wheel changes? Kind of like how a 35R and 30R housing of the same A/R have different volute sizes.

If you happen to see any good results on the S200SX on the AUS sites using the smaller housings let me know.

Actually most sites I see have data on the BEP .55 A/R housing! Seems incredibly small on T3 footprint.

[rajicase]

I'm running the 1.22 on mine. I like it.

[wazzu70]

In your application Raj I think that makes perfect sense. If you had, say a 1.8L I think a smaller housing would work better

I cant find any results or testing though. I just find it kind of odd.

[vollosso]

I dont think its comparable to look at different motors. Smaller motors need less compressor wheel. A 35r on a 3.2 i6 is a small turbo. Its a huge turbo on a wrx.


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[wazzu70]

I dont think its comparable to look at different motors. Smaller motors need less compressor wheel. A 35r on a 3.2 i6 is a small turbo. Its a huge turbo on a wrx.


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You mean turbine?

[Nutzy]

I dont think its comparable to look at different motors. Smaller motors need less compressor wheel. A 35r on a 3.2 i6 is a small turbo. Its a huge turbo on a wrx.

I *think* I know what you are saying...I think....

But if you are chasing 500HP you'll need around ~50lbs of compressor...roughly. This holds true if your donk is 2.0 or 3.0 (WRX was 2.5). I know that's bleedingly bluddy obvious to the responders on this thread, but hey. The same must apply to the turbine as well.

I think that the point the turbo comparison article was trying to make was that it seems the 0.63AR GT/GTX3582 seems to be 'the gun' unit to go for with quite a few of the 4cyl crowd in certain circles, whereas the results show that unless your going over 2BAR and revving the snot out of it, there was really little to be gained and a shit ton to lose. Maybe their is also the question that as far as wheel sizes go, the 3582 is perhaps not such a great match, whereas the 3576 is? 3076, not so much. In fact another back-to-back test compared GTX3076 to GTX3576 and it was a no brainer. The 3576 lost maybe 50rpm in spool and made more power everywhere.

Anyway, spit-balling over possible upgrades to my trusty S256 is interesting and all, but it isn't topped out yet. Close, but not yet. I seem to have confirmed now that a 600x300x76 IC will mount in the front of the E30 without major surgery, so I'll get one ASAP. I gotta get a BP gauge on my 6-1 collector and monitor that as well. Maybe a little bit of pre-comp H20? As it stands now and with new RSRR's on the rear, it is still getting a fair bit of tire slip in 4th (ZF6, so not 1:1). 3rd lights up 80% of the time and lays impressive 11's down the road! So moar powaz? Probably just bragging rights at this point!

[vollosso]

I meant at the same size turbine smaller motors will do better with smaller compressor wheel. It has to do with t/c wheel offset but look at the gtx maps and the flow vs pressure and look at their efficiency islands. The little 2l will be way left of a 3l or a 5l motor. They have nothing to gain in a 35r over a 30r. The pressures they need to make the 50# flow..



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[rajicase]

Why are you spinning those rsrrs? I get full traction in 2nd with them! I'm running 255/40/17 rsrrs at 32psi, -2 camber.

[vollosso]

Yeah, what alignment, suspension, and temperatures?


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[Nutzy]

Raji - Ahh, yes you have 255's and more weight, hence you hook. I'm only on 215's at the moment and will go to 235 on a 9" when I get the MZ3 rear end installed.

Vollosso - 12KG springs, very little camber, toe/camber adjusted but not sure what it is.

Re the compressor, yup, totally get your point now.

[rajicase]

Gotcha. These rsrrs are the shit!

[wazzu70]

I meant at the same size turbine smaller motors will do better with smaller compressor wheel. It has to do with t/c wheel offset but look at the gtx maps and the flow vs pressure and look at their efficiency islands. The little 2l will be way left of a 3l or a 5l motor. They have nothing to gain in a 35r over a 30r. The pressures they need to make the 50# flow..



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The compressor and turbine work the same no matter what. The issue is if you have enough exhaust mass flow to get the turbine up to speed with the A/R housing. If the compressor can not get up to speed its going to be hard to get that flooow to make the mad pauer.

Just another way to think of it. Compressor maps have pressure ratio, efficiency islands, flow rate, and wheel speed. Most people just look at the PR, flow rate, and maybe efficiency islands. That only works if the compressor can actually hit the RPM on the map! Key thing people miss.



Regarding the A/R data on a smaller 4cyl, Im just surprised as the S200 turbos are used a lot on EVOs and other smaller engines. Most of those use the really dinky .55 A/R.

[vollosso]

Waz, i think were somehow saying something similar if you compare your middle paragraph.



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[wazzu70]

Waz, i think were somehow saying something similar if you compare your middle paragraph.



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Yes, just explaining the "why" differently. Same thing in the end.

[ba114]

I seem to have confirmed now that a 600x300x76 IC will mount in the front of the E30 without major surgery...

If it will fit with the a/c condenser in there too, order me one too!

[Nutzy]

If it will fit with the a/c condenser in there too, order me one too!

Ha, OK.

Well the weekend was a blast! I travelled up to Cooma with a bunch of friends to run the Snowy 1000 where the mighty whitey E30 was entered. Two cars from our 'crew' were missing as they were not completed in time, but we had a 340fwkw Mitsu Mirage Auto, a 500rwkw 300ZXTT, my 360rwkw E30, a 1JZ Hilux Ute, and our sole lady driver in a 280awkw Evo. This is THE first motorsport event I've ever been in and I was a bit nervous about it TBH. First run I was not much good at all and hung up on the limiter in 1st, 2nd, 3rd, and 4th. Then I lifted in 6th when I got freaked out by the speed increase, realised I was only at 750M, then went WOT again. Every little movement of the car on the runway was wigging me out LOL! Run 2 I focused more on shift points and cared much less about the movement of the car. Run three I data logged and realised I was shifting at less than 6500 (around 6200). I only got 3 runs because of track issues with timing gear etc, but the car was perfect! Drove there, ran the event, drove home. Took a TON of tools and didn't even bust out a screwdriver!

1st run - 22.90 @ 237KPH
2nd run - 22.51 @ 247kph
3rd run - 22.45 @ 237KPH

Data log showed 54C intake temps in the top end on a 24C day, 11.9AFR, 219KPA boost, and 800C EGT in the collector. I was a bit concerned about the EGT...

Vids to come.

[vollosso]

Egt is all about cam, what cam are you running? How is it timed?

I need to look back at your timing table, too little timing can put extra heat in the collector.

What are you monitoring egt for, what is your goal with it? Id put egt on my leanest cylinder or id run one on each cylinder so i could tune accordingly.

Knowing the collector temp doesnt tell me a whole lot from a tuning perspective. If you have variance in a cylinder you wouldnt know..

You can time your cam off of collector egt on the dyno. knowing temp at peak power then you could tweak other cars off the dyno with an egt probe..

From all that i dont think 800c on a 20 second pull is a bad situation. 800c on a single pull might alarm me..

Haha.. im just rambling! Sounds like a fun afternoon!


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[wazzu70]

Sounds like fun! Also sounds warm. I need to go to Oz!

[BadBoostedBmwM3]

A bit of catch can building going on around here. Updated - - - So I was having a bit of a look at some compressor maps today, starting with the map for the S256 on my car. At 2.2PR (18psi) and 55lbs, it is pretty much right at the edge of the map and in the 60% line. Then I took a look at some maps for 65lb compressors such as GTX3576, EFR7670, and S258/9, and to get 65lb out of them at 2.5PR they are once again at the very edge of their maps and in the low 60%. On the other hand, GTX3582 at 65lbs is sitting pretty at around 74% with more to go. How much does this matter? Of course I know that 10-12% gain in efficiency is better in terms of lower shaft drive power and then lower BP as a consequence, but if 65lbs flow was your target, would one bother with the 3582 and live with the slower spool?

Okay, so I liked to be able to read compressor maps too. So, explain a little more please. What do you mean by the edge of the map and low 60%? When you say 2.2PR are you deducted atmospheric pressure to get 18psi?

[Nutzy]

Vollosso - EGT probe is in the collector, cams are stock and timed with the block. I got the probe cuz the tuner said he wished I had one so he could see where the temps were at.

Nick - Yep, it was a rad weekend and the temps were just fine and warm enough. We were trackside at about 545am when it was still single digits but OK for rushing to set up kept ya warm. The damned coffee van didn't arrive until about 0900! What were they thinking?!

BBBM3 - By edge of map I mean the RHS of it, not the surge line (LHS). Yes, 2.2 PR refers to the map markings, so 2.2 means 1.2bar boost.