sutyak's turbo focus

[sutyak]

Another video just driving normally. A bit boring but you get an idea what it sounds like and how aggressive the H&R suspension is.

[sutyak]

My GT2871R is in the for sale section now. I've decided I won't be going back to it at this point.
It's very likely I'll try a GTX3071R in the near future. I've had my eye on that turbo for a while now, and would like to see how it spools compared to the 3082. Going by the compressor map it looks like the PERFECT turbo for a 2.0L, but it certainly won't make the max power of the 3082.


Here is the monster I'm working with right now. Using the GTX3582 map since it shares the compressor side. The turbine map would be different.
You can see it spends most of the time before 4K RPM to the left of the surge line. No good.



Here is a map with the 3071 and 3076 and GTX variants overlaid.
The GTX3071 stays nicely on the right side of the surge line, and it would just scream at 25psi to 8K RPM. HP limit is going to be about 485whp though, compared to the 3082R's 625whp.
It should be a good compromise between big power and fast spool so it still feels like I have a turbo daily driving. It's very close to an HX35 map, but flows 5lb/min less.

[phillysrt4]

Its a good analysis! At the same time I think you may want to consider more than the map outline. Have you considered the efficiency islands as you approach peak power in the higher RPMS?

Here's my crappy drawings with the compressor maps. Notice how on the 71 at 55lb/min where it chokes out you're at the 60% or 65% efficiency island (hard to tell) whereas with the 76 you're in the low 70's at that flow.

Not saying the GTX3071 is a bad choice- IMO its one of the best "all around" choices in the 1.8-2.3 displacement range- but if you're enjoying the peak of the 3082 you might find the 3076 tradeoffs more enjoyable.

Either way I cant wait to see how this plays out!

[sutyak]

Well this might make my decision of going with a smaller turbo more difficult. I added data points from my actual data logging at 24psi to the earlier 3082R compressor map, which was an estimated flow. The estimate was very close, but the actual is slightly better, with it being just to the right of the surge line every point after 3500 RPM. That means while the 3082R is big, it's not TOO big for my 2.0L, just darn close!
The smaller, non-bold font is from my data logs, with the blue and black line.

[phillysrt4]

Wow that does make it tough indeed! It seems all you're really trading by going smaller is a SLIGHTLY better spoolup. You're going right into the sweet spot of the turbo as you hit peak power. It won't get any better as far as efficiency.

Can you save me some scrolling and let me know the AR of your hotside? I'm kinda with you and thinking of staying with the 82. The only reason why I wouldn't is if the ratio between the hot and cold sides is getting over 4:1. "Back in the day" a lot of people tried to port and clip the stock turbo on the SRT to get more out of it, but every increasing backpressure limited how much more you could get out of it versus a bigger turbo.

[sutyak]

Wow that does make it tough indeed! It seems all you're really trading by going smaller is a SLIGHTLY better spoolup. You're going right into the sweet spot of the turbo as you hit peak power. It won't get any better as far as efficiency.

Can you save me some scrolling and let me know the AR of your hotside? I'm kinda with you and thinking of staying with the 82. The only reason why I wouldn't is if the ratio between the hot and cold sides is getting over 4:1. "Back in the day" a lot of people tried to port and clip the stock turbo on the SRT to get more out of it, but every increasing backpressure limited how much more you could get out of it versus a bigger turbo.

Hot side is .63, which is what came with the turbo but also what I wanted to help with spool, and it looks like it does help. I considered .82, but I'd only go with that if it looks like the .63 is going to hold me back. I think the log manifold will be the choke point before the hot side.

[sutyak]

Dyno scheduled for Wednesday morning at Wolfpack Speed. Results will be posted Wednesday evening.

[PaxtonShelby]

^^^^ Giddy up!! Good luck!

[phillysrt4]

x2!! Please post up some numbers. Looks like you got the mad excel skills to superimpose some log data on the dyno graph too. This is gonna be awesome.

BTW - I don't think I would go AR .82 on the hot side. Looking at the GTX30 hotsides in .63 (if im reading the maps right) puts you at about a 3:1 worst case. not horrible, but not bad enough to switch to the 82 unless you're going with all new turbo.

[sutyak]

Car is running well and the tune is basically dead on. I'm psyched. I haven't been on a dyno in years. The last time my car only made 204whp for a split second at like 4500 RPM with a tiny IHI turbo. Tomorrow should be interesting if my fuel pump holds out. Fingers crossed my junk stays together and shows me some good numbers.

[PaxtonShelby]

Good luck!

[phillysrt4]

Absolutely! Good luck, and here's to 400+ at the wheels.

[PaxtonShelby]

So?????? How'd it go on this hot and sunny day?

[sutyak]

It certainly wasn't the day I was hoping for. The dyno was a nice, smooth line until 5K at full boost, then my ignition goes nuts. I'm not sure at the moment if I need to step down my plugs, close the gap, or if it's a more significant ignition issue.
What I do notice is this graph looks a LOT like my dyno graph from 2012 with my little IHI turbo. That was also on the same plug (Autolite 103, 1 step colder, 27 gap).
There was not any significant timing being pulled; a couple degrees at the very top, but nothing crazy that would attribute to the plunge in power.
So, I have some things to look into. First will be a colder plug.

Some of today's dynos. I did a 26psi pull for the heck of it and made 350whp/363wtq, but that's not exactly a win. It should make MUCH more than that.


Compare to one from 2012. Very different tune, different turbo, and different MAF configuration. Same type of plugs. Hits peak boost, then goes to crap.

[phillysrt4]

If you had an SRT i would say "boost leak" but in your case yeah, maybe a colder plug would help.

[sutyak]

If you had an SRT i would say "boost leak" but in your case yeah, maybe a colder plug would help.

The only boost leak I had was when I blew an intercooler pipe on the way home. This is why I always travel with 10 and 11mm deep sockets...

[JeffreyCole]

Were you tuning on the dyno or just making power pulls?

[sutyak]

Were you tuning on the dyno or just making power pulls?

Logging and power pulls mainly. Only tune change I made was pulling some fuel up top, but that did not help. That just resulted in some timing being pulled. As far as AFR and timing goes, my tune is as close as I can get it until I figure out this ignition issue. I'm sure that will cause some havoc on my current tune.

[no1sirbutler]

D you have a graph of your A/F?

[Tom]

Im going to guess you run a 12.5@108