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The FD's itching for action! This JDM legend is prepped and primed for another thrashing.
The M3 received the same treatment as the RX7 and is doing well. The engine is a masterpiece so buttery smooth and linear. Not to be outdone, the daily driver went in for some TLC too, and it's holding its own against the M3 and RX7! It's proving to be a fantastic all-rounder, and honestly, seeing it perform so well makes me understand why the F10 M5s have such a reputation, a wolf in sheeps clothing as they call it.
So which car should I take for a drive?! Always a tough choice.
Ran an random experiment at low boost to determine how anyone or more importantly how I can run the best and fastest draggy time for the 100-200km/h using the stock fd box with a max engine rev limit of 9krpm, some streetports and most bridge ports will likely fall into this category.
In my last validation test, holding third gear to 8700rpm for 60-100mph was way quicker than shifting to fourth, so I wanted to see if the same trick would work here in the 100-200 runs.
For the first test, I just kept third gear in all the way to 8700rpm and then shifted to fourth. Let's see if it beats shifting earlier?! It's a very conservative tune as only testing but it ran a respectable 7.85s 100-200.
For the second test, I shifted early around 8000rpm ish in 3rd gear.
Wow, that was a close one! Even though the run wasn't perfect due to a tiny slope messing with the data (seriously, by only 0.03%!), it turns out my hunch was right.
For those of you running a stock FD gearbox (me included) with a 13b engine limited to around 9k rpm, shifting at 8700rpm or 8000rpm in 3rd gear seems to be just as good in the 100-200 sprints. Honestly, with the manual transmission, that little bit of difference did not seem to make a huge impact.
Now, if you've got a fancy semi-PP setup that lets you scream past 9k rpm to 10k or even 11k, then yeah, holding third gear longer to the engines rev limit will definitely shave off some time in that 100-200km/h sprint – maybe like 0.4-0.5 seconds. But for most of us mere mortals, just focus on that sweet spot and shift when it feels right. Because at the end of the day, with a manual, that perfect shift is gonna be tough to nail anyway and the vast majority of us will loose 0.4-0.5s in the manual shift for the 100-200 runs. In summary, shift up when you are ready.
For me the above result sealed the deal. Holding onto third gear all the way to 8,700 rpm would not give me any advantage because the stock shift was inevitable resulting in time loss. So, for the higher boost runs, I decided to shift up around 8,000 rpm instead.
This is where things got interesting. Pushing things harder meant I maxed out my fuel pump and injectors! I Had to play with the tuning to find a happy medium between how much fuel the injectors were delivering (duty cycle) and what the fuel pump could handle. In the end, I ended up lowering the base fuel pressure to 3.5 bar to get everything working smoothly. This resulted in something I did not think was possible in a G35 1050 and a street port....yet here we are!!
Finally in the 5s range. The G35 wants another 3-4psi to get into its sweet spot. I'll do a deeper dive with data on the boost, afr/lambda etc etc used on this run.
Totally agree and you should shift up whenever you feel is right for your setup. Dyno tests and draggy tests are two different worlds though. That being said...I have a Turblown UIM sitting in my storage right now. Once I address the fuel system...I will be testing on draggy, time will tell.
Assuming ignition tune is reasonable and target AFR fairly static across enginespeed, multiplying the fuel quality by rpm and plotting across gear ratios should get you a close proxy for power in gears to see the crossover point (if there is one for the ratio split) or way to get most power under the speed curve without actual dyno data. I assume you may be able to generate a derived power channel in the software for full in gear pulls or is it locked down in toddler mode if you don't have a full vbox system?
i've been transrating my Japanese Rx7 magazines, and there are a few tuning articles with Revolution, and the 0-400m car they built, they were focusing on the response in the 5500rpm area, which is where you end up after a shift.
the magazines are old, so the combo is going to seem weird, but the 0-400m car is a T88-34D but they went to a smaller a/r housing (stock kit was a 22cm?, so 18cm is the next smaller one)
they also prefer the 50mm manifold over the 60mm. 90mm exhaust.
engine is a street port, motec ecu, 570ps at 1.5kg. they have an engine dyno, so not sure if this is at the engine, or wheels or what
car ran 10.830 at 210kph/130mph, which is fast for 1999
in 2024, concept still applies, but you'd run a turbo that spooled faster AND had more top end
25+ psig boost is going to be the most efficient power range for the G35-1050 turbo. Since you’re not likely to exceed 700 hp you can likely go much higher if it’s tuned for it and not have to worry about overspeeding the compressor wheel.
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25+ psig boost is going to be the most efficient power range for the G35-1050 turbo. Since you’re not likely to exceed 700 hp you can likely go much higher if it’s tuned for it and not have to worry about overspeeding the compressor wheel.
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Thats the idea get upto 26psi and keep the revs to 8krpm or below as unsure of the emap data. I am in the 1.21 ar so hoping that helps.
the AR peak flow is sufficient for over 600 whp imo, but it probably depends more on the turbo manifold, exhaust system, and I can’t remember how the induction system ended up. And also assumes everything else supports it properly. You have a lot of coverage to play with, but as you note the exhaust side is going to be the limiting factor.
the AR peak flow is sufficient for over 600 whp imo, but it probably depends more on the turbo manifold, exhaust system, and I can’t remember how the induction system ended up. And also assumes everything else supports it properly. You have a lot of coverage to play with, but as you note the exhaust side is going to be the limiting factor. .
Thanks that is very helpful.
I was looking into emap data for a G35 1050 on a 13b and it seems there was some data available from one of Robs videos. I would take the below with a pinch of salt....but in his semi pp setup running a t4 1.06 ar variation of the turbo with E85 fuel above 60% TP for 25-26 Map the emap was showing as 30psi at 86-8700rpm. The outlier being when the TP is reduced to 54% at 25psi the emap was showing 36psi. This to me seems an inconsistent result, an anomaly i cant explain...I thought more load on engine should mean more emap and less load meaning less emap...I could be completely wrong here.
I am running pump fuel so injecting 30-40% less volume of fuel thus my demands of the turbine wheel should on balance be that much lower than someone running E85?
Question to the group, we know E85 requires 30-40% more fuel to make the same power as pump 99ron fuel?
Does that also mean 30-40% more exhaust gases and therefore higher Emap (than pump 99 fuel) due to greater demand from the turbine wheel? is there a ratio, or is it 1:1?
you know he had the 1.21 AR v-band without semi PP before that, right? Semi-PP was not the right choice for that turbo was part of the issue. It made 630 whp on the 1.21 A/R street port and then had boost leak issues. They then built the semiPP engine and swapped over to the divT4 1.06 setup as I recall.
However, he did make 560 ft-lbs @4200 rpm and 32 psig on the 1.06 just trying to see how fast he could get the boost up at low rpm. That was pretty amazing, but overall it has too much emap for semiPP on the top end.
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I know that and the emap data above reflects the t4 1.06 setup with the semi pp.
To clarify the 1.21 vband above is a reflection of my setup...the below where there is emap data is robs current G35 setup or at least as posted at the time on the video.
Question to the group, we know E85 requires 30-40% more fuel to make the same power as pump 99ron fuel?
Does that also mean 30-40% more exhaust gases and therefore higher Emap (than pump 99 fuel) due to greater demand from the turbine wheel? is there a ratio, or is it 1:1?
a couple things. to make the math easy. on pump gas, if you run 10:1 afr, the fuel mass is 10%, so if you did 50lbs minute of air, the fuel mass is 5lbs, total that needs to go through the exhaust side is ~55lbs minute. you can split it between the wastegate and the turbine.
E85 adds more fuel mass, but its like 40% more than 5lbs, so its like 6.5 or so.
does it matter? yes. does it matter a lot? probably not.
a couple things. to make the math easy. on pump gas, if you run 10:1 afr, the fuel mass is 10%, so if you did 50lbs minute of air, the fuel mass is 5lbs, total that needs to go through the exhaust side is ~55lbs minute. you can split it between the wastegate and the turbine.
E85 adds more fuel mass, but its like 40% more than 5lbs, so its like 6.5 or so.
does it matter? yes. does it matter a lot? probably not.
Thanks mate, you've answered the exam question. Using your math above E85 requiring 40% more fuel, then fuel mass would be around 7 lbs (5 lbs + 2 lbs increase). This leads to a total exhaust mass of roughly 57 lbs/minute for E85 vs 55 for pump fuel, reflecting in 2psi less back pressure all things being equal. Not a huge difference but certainly helpful to know.
What is your take on the below?
At 41%TP the emap looks crazy high but at 60% TP and above its far more reasonable.
This leads to a total exhaust mass of roughly 57 lbs/minute for E85 vs 55 for pump fuel, reflecting in 2psi less back pressure all things being equal. Not a huge difference but certainly helpful to know.
i doubt that 2lbs would make much difference in backpressure. although it depends.
What is your take on the below?
At 41%TP the emap looks crazy high but at 60% TP and above its far more reasonable.
with my car, the stock S4 turbo hit choke flow at ~30lbs a minute, at 7000rpm backpressure was high. (15psi with 8psi of boost)
i put a bigger compressor wheel in it, and at ~40lbs a minute backpressure didn't change, which was kind of a mind blower. (15psi of backpressure and boost came up to 13-14)
i can't explain why when the throttle isn't open, EMAP is higher. although if the turbo is out of its efficiency range, it takes more power, and backpressure goes up, it could be something like that
i doubt that 2lbs would make much difference in backpressure. although it depends.
with my car, the stock S4 turbo hit choke flow at ~30lbs a minute, at 7000rpm backpressure was high. (15psi with 8psi of boost)
i put a bigger compressor wheel in it, and at ~40lbs a minute backpressure didn't change, which was kind of a mind blower. (15psi of backpressure and boost came up to 13-14)
i can't explain why when the throttle isn't open, EMAP is higher. although if the turbo is out of its efficiency range, it takes more power, and backpressure goes up, it could be something like that
Very interesting indeed.
I would have thought Emap should correlate with throttle position, increasing with higher throttle openings and higher boost. In Robs emap data there is one pattern to be noted, lower TP 55% or below results in a higher emap almost too high to be sensible or reasonable and high TP 60% and above gives more reasonable readings noting less emap or reasonable figures which make more sense.
On balance i suspect a vacuum leak causing inconsistencies in pressure readings and if the leak is on the pressurized side (between the turbo and the throttle body). This leak could create a situation where Emap overestimates the actual pressure, especially at lower throttle positions where the vacuum is strongest. Alternatively, it could be poor sensor calibration or something simple.
I would have thought Emap should correlate with throttle position, increasing with higher throttle openings and higher boost.
if you asked me before a test like that, what i thought backpressure would do, i would agree with this. however i also wouldn't be surprised to be wrong
Its normal for emap to be high under light load/boost at partial throttle compressor surge.
On my FC before I ported my manifold and turbo exhaust housing (dropping velocity for less boost creep) under partial throttle emap would push my 60mm external WG open.
We are talking driving around parking lot light load and 5-10psi boost at 2-2,500rpm.
It takes a LOT of work from the exhaust turbine to push the compressor through compressor surge and choke flow states.
I would have thought Emap should correlate with throttle position, increasing with higher throttle openings and higher boost. In Robs emap data there is one pattern to be noted, lower TP 55% or below results in a higher emap almost too high to be sensible or reasonable and high TP 60% and above gives more reasonable readings noting less emap or reasonable figures which make more sense.
On balance i suspect a vacuum leak causing inconsistencies in pressure readings and if the leak is on the pressurized side (between the turbo and the throttle body). This leak could create a situation where Emap overestimates the actual pressure, especially at lower throttle positions where the vacuum is strongest. Alternatively, it could be poor sensor calibration or something simple.
If you are still reaching target pressure behind a partial throttle you need more pressure in front of it. Closed loop boost control without a TPS/torque demand scalar will do exactly that. Close the wastegate to give more drive energy to try to maintain target manifold pressure with more intake resistance. You need more energy to overcome more restriction at the same (very close to first order ignoring the VE bias from the rising EMAP) mass flow. That's why people usually implement TPS scaled proportional boost targeting if they aren't running an independent pre-throttle reference to regain some torque demand linearity otherwise the closed loop boost control just fights your pedalling until the intake restriction is too high.
If you are still reaching target pressure behind a partial throttle you need more pressure in front of it. Closed loop boost control without a TPS/torque demand scalar will do exactly that. Close the wastegate to give more drive energy to try to maintain target manifold pressure with more intake resistance. You need more energy to overcome more restriction at the same (very close to first order ignoring the VE bias from the rising EMAP) mass flow. That's why people usually implement TPS scaled proportional boost targeting if they aren't running an independent pre-throttle reference to regain some torque demand linearity otherwise the closed loop boost control just fights your pedalling until the intake restriction is too high.
Thanks mate, that is very helpful.
looks like its not ideal to reach target pressure with partial throttle. Ideally I was hoping to have wot emap data on the G35 1050 but this does not exist in the rotary world. Robs G35 emap data is certainly useful but perhaps not ideal. I'll have to put in some emap sensors in my setup and see what emap looks like at 100% wot with the G35 1050.
It's certainly not ideal to reach target boost pressure at 40-50% TP...simply because emap seems to sky rocket to almost 1.7 or 2:1 which is kinda crazy and likely not a true reflection of the turbo maxxing out.
However, above 60% TP using robs emap data is roughly 1.2:1 which is very reasonable.
Yh my bad, should have clarified, there is no rotary emap data for a 1050 1.21 ar, only the 1.06 t4 emap data which was shared.
Meanwhile, comparing apples and oranges Garrett's site suggests (https://www.garrettmotion.com/news/n...garrett-turbo/)
G35 1050 1.21ar being pushed to its limits on a 2jz
Emap 48psi
Map 31pi
Approx 1.5:1 Emap ratio.
Now if i take an average of Emap figures for the 13b semi pp using the G35 1050 T4 1.06ar. The average consists of the 2 Low TP pulls to hit boost and 2 higher TP pulls. This gives an approx 1.5:1 Emap ratio. I suspect the 1.21 ar turbine housing will likely have better exhaust flow by 3.5lbs inline with Garrets data compared to the 1.06ar plus approx 40% less volume of exhaust gas using 99 pump fuel over E85.
It's not perfect, and can't say for sure it's scientifically accurate, but based on the very limited data available, it seems like Emap starts to get about 1.5 times higher than Map when the pressure goes above 22psi. That's around the point where the Emap for the 13b semi pp G35 1050 1.06ar setup started exceeding the Map.
looks like its not ideal to reach target pressure with partial throttle. Ideally I was hoping to have wot emap data on the G35 1050 but this does not exist in the rotary world. Robs G35 emap data is certainly useful but perhaps not ideal. I'll have to put in some emap sensors in my setup and see what emap looks like at 100% wot with the G35 1050.
It's certainly not ideal to reach target boost pressure at 40-50% TP...simply because emap seems to sky rocket to almost 1.7 or 2:1 which is kinda crazy and likely not a true reflection of the turbo maxxing out.
However, above 60% TP using robs emap data is roughly 1.2:1 which is very reasonable.
Definitely needs to be considered when mapping and why people will use TPS multiplier maps if not using IMP:EMP vs rpm for main load tables with an absolute pressure vs rpm AFR target table (not so long ago that was just about only motec in the hobby/privateer tuning world). If you only log at partial throttle and extrapolate VE at higher boost from that the numbers will be lower than at WOT so will run leaner than expected.
04-27-24, 11:41 AM
