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Discussion Starter · #1 ·
I was finally able to dyno the SIR Stage 3 turbos, which are the Gen2 GTX3071r's in the stock turbofold. I had the turbofolds custom CNC machined by Greggs Customs to enlarge the wastegate hole as well as unshroud the valve and a custom larger inconel wastegate puck machined for the larger wastegate hole. This completely eliminates the boost creep issues associated with running GT30 turbos in a stock turbofold. You can see my post about this modification below.
CNC Ported Wastegate hole and oversize flapper - boost...


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The setup is a stock motor and trans, but with all the usual bolt on parts with the addition of a custom short route race intercooler that I built and a boost actuated 4" dump below the car that I fabricated.


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The results are below in the dyno graph (750hp/625tq), but let me briefly decode these three 3rd gear runs.

Red & Blue - 4" dump open
Green - 4" dump closed, which means it's running through a 3.5" CAT and stock mufflers

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Below is the data log from my final run showing intake cam timing, ignition timing, boost, and knock sum. You can see that I ramped in more boost after 6K rpm to try and maintain torque levels at 600ft-lbs. I likely could have pushed it more because it wasn't showing any kind of knock, but I felt this might be a good stopping point after 6 runs. Car feels very strong and seems to be way less knock prone with this larger 55mm turbine.

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e85 or pump gas?
 

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Discussion Starter · #4 ·
e85 or pump gas?
It was disclosed in the title, "on pump gas tune." However, you can typically tell based on the ignition timing. A stock motor pump gas tune with a small turbine (<50mm) will typically only allow for ~6-7deg at peak torque ramped to ~16-17deg at redline assuming all of the supporting mods. However, with the larger 55mm turbine wheel this lowers the drive pressure and will typically allow for a few degrees more timing. In my case, I only bumped up timing ~1deg vs the XonaGreens to be conservative. If you look at an E85 tune they typically add 2deg to peak torque and 5deg at redline vs a pump gas tune, but that can vary depending on the tuner and how aggressive/conservative they are.
 

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Once again, excellent info!
 

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Discussion Starter · #7 ·
I thought it would be interesting to show a comparison of the dyno logs from the XonaGreens ([email protected]) vs the SIR Gen2 GTX3071r ([email protected]). While this was the same dyno that I used previously, the shop completely wiped their software so they did not have any of my old dyno runs to show the dyno graph comparison. Below is the data log from yesterday's best pass([email protected]) vs the best pass with the Xona Greens ([email protected]).

Red - Xona Greens
Blue - SIR Gen2 GTX3071r

You can see that I was able to run more timing (~1deg across the RPM range) and essentially the same boost level, but netted an additional +44hp.

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If you look at the boost response based on these logs, the Xona Green's out spool the SIR Stage 3 by 500rpm when reaching 20psi in 3rd gear. Bill said my setup is spooling on the lower side and he typically sees about 300rpm better. He also recommend that I ditch the OEM 3 port and go with a 3port MAC valve because apparently the stock units leak, which may or may not be affecting the spool. Anyway, if you look at the ignition timing and intake cam timing they differ and both can and will substantially affect spool.

When you retard timing on spool like I did with the Xona Greens, it creates additional exhaust energy because you're burning fuel in the exhaust and increasing your EGT's, which spool the turbo faster. I'll have to repeat the logs on the GTR, but if you look at the graph below based on my EVO IX you will see that I gained 200rpm in spool by dropping timing during spool. I suspect if I had run 10deg on spool with the SIR Stage 3 they would spool slightly better.

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You have a similar effect with intake cam timing and spool. I probably should actually compare 30deg vs 35deg during spool on the GTR to see if it actually makes a meaninful difference, but in general I try to ramp in as much intake cam timing as possible to promote spool and right before I hit peak boost I quickly ramp out intake cam timing to ~20deg to promote flow and then ramp it down to 0deg around 6K RPM. This is just a general rule of thumb for a tune because the optimal curve would have to be determined based on a fair amount of dyno work. If you look at the graph below from my EVO IX, you will see how going from 25deg to 30deg of intake cam timing resulted in increased spool. I suspect my going from 30deg with the Xona Greens to 35deg with the SIR Stage 3 would offset the losses I have from the reduced ignition timing on spool. At least on my setup, the spool difference appears to be about 500rpm.

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Below is the Xona Green dyno graph and the SIR Stage 3.

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James, thanks for sharing all of that data. How is drivability in part throttle boost compared to the Greens... are you running up against the surge line at all with the larger 3071 turbos?
 

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Discussion Starter · #10 ·
James, thanks for sharing all of that data. How is drivability in part throttle boost compared to the Greens... are you running up against the surge line at all with the larger 3071 turbos?
Despite these turbos running the OEM IHI compressor housing with no surge port, I have not experienced any part throttle surging. I'll need to take it on the highway and do some low RPM (2K) pulls in Manual 4th, 5th, and 6th to see if they surge coming onto boost.
 

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Discussion Starter · #11 ·
You have a similar effect with intake cam timing and spool. I probably should actually compare 30deg vs 35deg during spool on the GTR to see if it actually makes a meaninful difference, but in general I try to ramp in as much intake cam timing as possible to promote spool and right before I hit peak boost I quickly ramp out intake cam timing to ~20deg to promote flow and then ramp it down to 0deg around 6K RPM. This is just a general rule of thumb for a tune because the optimal curve would have to be determined based on a fair amount of dyno work. If you look at the graph below from my EVO IX, you will see how going from 25deg to 30deg of intake cam timing resulted in increased spool. I suspect my going from 30deg with the Xona Greens to 35deg with the SIR Stage 3 would offset the losses I have from the reduced ignition timing on spool. At least on my setup, the spool difference appears to be about 500rpm.

View attachment 398974
I went out today and was playing around with the tune and decided to compare 30deg vs 32deg vs 36deg of intake cam timing during spool to understand if running more than 30deg actually provides benefit. I will preface these results by saying they are just 3 isolated logs so not saying it is definitive proof, but it looks like there is a point of diminishing returns over 32deg during spool. The only thing that causes me pause is that ignition timing is lower with the 30deg and 32deg runs so not sure if that is playing into the initial spool delay.

I'll try to repeat this tomorrow with 6 runs back to back switching between 30deg, 25deg, and 36deg each time. Based on the stock turbos running 25deg should hurt spool, but might as well see if it applies to this setup.

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I went out today and was playing around with the tune and decided to compare 30deg vs 32deg vs 36deg of intake cam timing during spool to understand if running more than 30deg actually provides benefit. I will preface these results by saying they are just 3 isolated logs so not saying it is definitive proof, but it looks like there is a point of diminishing returns over 32deg during spool. The only thing that causes me pause is that ignition timing is lower with the 30deg and 32deg runs so not sure if that is playing into the initial spool delay.

I'll try to repeat this tomorrow with 6 runs back to back switching between 30deg, 25deg, and 36deg each time. Based on the stock turbos running 25deg should hurt spool, but might as well see if it applies to this setup.

View attachment 398996
Just to clarify, you are keeping the engine timing the same but testing cam timing at 36, 30 and 25 deg to see if it helps with spool?
 

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Discussion Starter · #13 ·
Just to clarify, you are keeping the engine timing the same but testing cam timing at 36, 30 and 25 deg to see if it helps with spool?
Correct, ignition timing needs to be a constant so I can isolate the effects of intake cam timing. It's been raining in Charlotte for the past 2 days so I've been unable to do the tests.
 

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wow, lots of really great info here. I'm currently building my tune for some Cicio Gateways that are "in the mail" this is very helpful to see I'm on the right track for initial timing(both ign and cam).

Have you considered running more cam advance on the high end? on My Evo x it allowed me to run several more degrees of ignition on pump and make a fair bit more power. The best theory I could come up with was that it lowered my peak to mean cyl press ratio enough to get more timing without knock on our crappy 91 oct. the results were plainly obvious though.

I haven't done with with the GTR yet since I basically only have midpdipe and CB installed and virtual dyno has enough variation as is. New tune will be Speed Density, flex fuel, FBO + the gateways, 17 psi cruiser map and 20 psi race map. If you don't mind sharing, I think a WGDC map comparison for the Xona's vs the SIR 3071r's would be neat to digest.

Also, I saw somewhere that you had ATR 2009 and somebody wanted you to look at something in a newer map. I have ATR for 2015 and 2016, maybe we can collaborate if you ever want to look in one of those years LMK.

thanks for keeping the forums alive!
 

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eh disregard my running more cam advance up top question. less intake advance= more overlap facepalm. With the Evo I could control both cams and made more overlap to get those results. will keep mine at 0* full RPM... slow morning..derp
 

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Discussion Starter · #16 ·
eh disregard my running more cam advance up top question. less intake advance= more overlap facepalm. With the Evo I could control both cams and made more overlap to get those results. will keep mine at 0* full RPM... slow morning..derp
Correct, lower intake cam timing pushes the cams in the direction of "overlap." When I was dyno tuning on stock turbos I compared 0deg vs -2deg on the topend and there was no difference in power.
 

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Discussion Starter · #17 ·
wow, lots of really great info here. I'm currently building my tune for some Cicio Gateways that are "in the mail" this is very helpful to see I'm on the right track for initial timing(both ign and cam).

Have you considered running more cam advance on the high end? on My Evo x it allowed me to run several more degrees of ignition on pump and make a fair bit more power. The best theory I could come up with was that it lowered my peak to mean cyl press ratio enough to get more timing without knock on our crappy 91 oct. the results were plainly obvious though.

I haven't done with with the GTR yet since I basically only have midpdipe and CB installed and virtual dyno has enough variation as is. New tune will be Speed Density, flex fuel, FBO + the gateways, 17 psi cruiser map and 20 psi race map. If you don't mind sharing, I think a WGDC map comparison for the Xona's vs the SIR 3071r's would be neat to digest.

Also, I saw somewhere that you had ATR 2009 and somebody wanted you to look at something in a newer map. I have ATR for 2015 and 2016, maybe we can collaborate if you ever want to look in one of those years LMK.

thanks for keeping the forums alive!
Just like your AP, ATR is specific to your vehicle and it won't let you open maps from other years or even the same year from other ATR users. Therefore, the only way to share data is to import into Excel and then cut/paste into your maps.

Regarding the WGDC map, I am replacing the OEM Pierburg 3port boost solenoid with a MAC 3port solenoid in the hopes of having better control of the boost curve specifically in the area where I initially hit full boost. It either overshoots the boost target or I have to soften the response in this area to avoid a boost spike, which should not be the case. When I get this done I will post my 22psi map and then explain the approach, which you can then use to quickly create your own 17psi and 20psi maps.
 

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Guess I should have known ATR wouldn’t let you open a map created for a different AP. Would have been cool
 
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