When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
"If you get a draggy device you can do custom mode runs like a 60-100mph or whatever parameter you choose for the tarmac you have to safely conduct the runs."
can you visit one of your logs and check your Link data?
You do want GPS validation of calculated road speed as that can have a significant impact both in terms of real accelerated mass but also aero drag, but if you are logging with anything with decent/smoothed/integrated GPS and other vehicle speed data I don't see the need for draggy specifically. It would require the cost of that logger to be entirely frivolous to someone if they already had a decent Motec or other logger system integrating GPS data.
You may have to adjust your air vs wheel power figure a little too, the turbine and compressor efficiency is both up on historical which also improves IMP:EMP so pumping loss is down and mass flow rate for boost up.
one by the ECU. RPM was logged at 500 Hz. another log within my Dell CORE i7 laptop.
time is solid IMO. time is probably THE single most important factor on any ECU... i am able to log at 1000Hz. case closed on time.
RPM is solid, being digital and electronic. Hall pickup.
as to speed... i am getting speed thru the digital output from my Tremec. it is linear as it is mechanical. i run it thru the newest Dakota Digital converter (SGI 100BT). the ECU speed agrees with my speedo which is not surprising since it gets the same signal from the DD module.
i also have a Racelogic (GPS) VBOX that agrees as to speed..
finally, just to crosscheck, i did a calculation using RPM (7867), third gear ratio (1.30), rear ratio (4.1) and tire diameter (24.8). 110 ECU indicated works out to 108.89 mph.
i do feel my data is solid. i also feel my power calculations are on the money, about 600 tops. the factors are pretty simple.
so do i think my my FD at 600 would run with an 800 hp FD. of course not.
You cannot compare draggy data and wheel speed data. They are not the same.
I would suggest you get a draggy and get some real world data that is comparable on the same platform and see what it looks like.
My Rear wheel speed data never ever matched up with my Draggy, it would always show I was considerably faster on my rear wheel speed data since the car was always spinning a little.
There is a reason everyone uses GPS data for actual speed and positioning and slip ratio (with lateral and longitudinal test data) for acceleration optimisation for race data analysis.
the Racelogic VBOX is basically a motorsport grade Draggy, is it not? Or has Draggy replaced it by now? I mean, VBOX was the thing to have for all track measurements.... Can the datalogs be compared?
Anything that runs an external gps aerial 10hz with accelerometer smoothing or 100hz GPS should be on the money. If someone really wants to edit a draggy result I'm sure they could anyway.
Racetech and Racelogic has good clubsport level units 15 years ago, most of the dashloggers should do it now.
You can always generate your own data and that's great. If you want to compare your car to others you need to use the same platform and same comparable variables for you to be able to draw any conclusion.
Not sure what the issue is, get yourself a $100 draggy and get some data.
one by the ECU. RPM was logged at 500 Hz. another log within my Dell CORE i7 laptop.
time is solid IMO. time is probably THE single most important factor on any ECU... i am able to log at 1000Hz. case closed on time.
RPM is solid, being digital and electronic. Hall pickup.
as to speed... i am getting speed thru the digital output from my Tremec. it is linear as it is mechanical. i run it thru the newest Dakota Digital converter (SGI 100BT). the ECU speed agrees with my speedo which is not surprising since it gets the same signal from the DD module.
i also have a Racelogic (GPS) VBOX that agrees as to speed..
finally, just to crosscheck, i did a calculation using RPM (7867), third gear ratio (1.30), rear ratio (4.1) and tire diameter (24.8). 110 ECU indicated works out to 108.89 mph.
i do feel my data is solid. i also feel my power calculations are on the money, about 600 tops. the factors are pretty simple.
so do i think my my FD at 600 would run with an 800 hp FD. of course not.
"conundrum"
"a difficult problem or question"
You've already mentioned in your previous post you dont think your time is faster than Omar's yet by your own calculations your 70-110 time is way faster which suggests something is wrong. My primary limitation for 100–200km/h runs is that my current logs don’t include GPS-derived speed, and my wheel speed sensors aren’t reliable for this type of performance measurement. To address this, I rely on the Dragy GPS, which provides consistent and comparable data across different platforms. I can compare acceleration against my M3, my mates 1000hp GTR or Omars RX7 on the other side of the world. Effectively we are playing the same game.
That's how the RX7 Dragy Leaderboard was created and verified. The video overlay along side the draggy report cant be doctored because of 2 factor validation. The video overlay must match the report and any fake results will be quite obvious.
For the acceleration data to be meaningful we all need to be playing the same game. Otherwise, we can have these outliers where 600hp rx7s are running faster acceleration times than a 800hp rx7.
Last edited by rx7srbad; Dec 14, 2024 at 10:25 AM.
as it turns out, my RaceLogic PerformanceBox is easily programable as to start and end speed and is GPS based so i will simply do another run from 70 to 110. when i initially posted in your thread i had no idea as to how my run compared to the Dragy runs. i would like to understand why the difference. as i have previously posted, an 800 hp FD beats a 600 hp FD. my problem is the time is accurate and my speed checks. i was logging rpm at 500 Hz and the plot shows no indication of wheelspin at 110. in spite of this, i expect my next run to fall into where the 600 hp Dragy runs are... 'sorry to have polluted your thread.
as it turns out, my RaceLogic PerformanceBox is easily programable as to start and end speed and is GPS based so i will simply do another run from 70 to 110. when i initially posted in your thread i had no idea as to how my run compared to the Dragy runs. i would like to understand why the difference. as i have previously posted, an 800 hp FD beats a 600 hp FD. my problem is the time is accurate and my speed checks. i was logging rpm at 500 Hz and the plot shows no indication of wheelspin at 110. in spite of this, i expect my next run to fall into where the 600 hp Dragy runs are... 'sorry to have polluted your thread.
No worries at all. Racelogic is meant to be a decent gps based box. I think the Officially Gassed youtube channel uses a racelogic vbox setup to record all their 100-200km/h and 1/4 data. These times are comparable to the draggy as their 100-200 data seems reliable and reasonable. What times are being reported on the vbox itself? that might be a better insight than the link logs.
After numerous 100-200 run I decided to tick a wishlist item and booked a track day at the legendary and scenic Anglesey Circuit in Wales.
Met up with a friend that races in the MX5 NC Series who knows the track well.
Some pics on the driveway at the Air Bnb at Anglesey.
The drive to Anglesey Curcuit is beautiful as well
The track is sensational and the views are breath taking.
Because an FD is involved something had to go awry. I lost 3rd gear and the FD had to be recovered to Tims at RX Motors to get a new gearbox.
In Fairness, my box did a splendid job - over 320 100-200km/h runs in mexico and numerous track days. This was bound to happen at some point.
Tim sent me some photos of 3rd gear. It was time to retire this gearbox.
We are lucky to have such a great community as I was able to source a low mileage box from the RX7 Tribe group in a few days. This box comes from an oe twin turbo FD.
Xmas presents from me to myself - Delivered by Santa!
Enter G40-900 1.19 T4 This pretty much wraps up the updates for this year.
Tim is working on upgrading the fuel system. For the time being i've replaced the gearbox with a low mileage oem box.
I will at some point next year switch turbos from my G35 1050 vband 1.21ar to the G40 900 1.19 T4 and see how it does.
Can a G40 900 truly run low 5s 100-200km/h? lets find out next year.
Last edited by rx7srbad; Dec 31, 2024 at 03:38 PM.
While the FD is under the knife and getting some well deserved rest, upgrades and maintenance.
I've been daily driving my E92 M3 for the past couple months. Its a privilege and pleasure to be able to do this because the V8 is a thirsty animal but it's not enough to scare off Rotary owners.
I also put a stage 2 Package on the M3 to get it to drive how it should have done from the factory.
Stage 2 Map 2 Pipe Mod - to get more V8 noises Decat Pipes to replace the OEM Cats
Daily driving the M3 has not been without cost - its picked up a few battle scars from the street.
OEM 100-200km/h
Stage 2 - A solid 1.18s improvement in acceleration for a NA machine. I'll take that. Its no 100-200 monster but its a lot of fun for street use. I really love this generation of the M3 and imo the absolute bestever M3.
Have a Great New Years!!
Last edited by rx7srbad; Dec 31, 2024 at 04:09 PM.
Enter G40-900 1.19 T4
I will at some point next year switch turbos from my G35 1050 vband 1.21ar to the G40 900 1.19 T4 and see how it does.
Can a G40 900 truly run low 5s 100-200km/h? lets find out next year.
Are you turbine limited on the G35? Why go with the G40-900 and not the 1150?
Are you turbine limited on the G35? Why go with the G40-900 and not the 1150?
At the moment, the G35 isn’t turbine-limited, but it will be when running 30-35 psi. To control backpressure, I anticipate holding 32-35 psi up to 7000 rpm then bleeding off boost significantly approaching 8000+ rpm.
The G40-900 is expected to provide better spool/response than the 1150 while avoiding any significant power drop-off. I’m confident this configuration will result in a more efficient setup, producing more power and torque throughout the rev range without sacrificing performance compared to the 1150.
Ideally, I would like to see mid to low 5s range 100-200 with a broader powerband from 4500 to 9000 rpm ideally on pump fuel and wmi. The 2 changes that should help will be the g40 900 and the turblown uim. I’ll be testing this on my 13B streetport and validating with draggy 100-200 times.
I don't want to be a downer but the 62mm inducer is probably a touch small for an extend port with aftermarket manifold targeting 30-35psi even "only" on water assisted pump fuel which doesn't achieve as much evaporative charge cooling.
At 3.2barA or ~32psi manifold pressure, if you are somewhat optimistic with filter restriction and intercooler pressure differential the 125k speed line is less than 80 pounds flow.
I'm guessing with extend ports and new intake it will want to peak at 8000rpm, thats ~ more like 95lbs and 3.5PR on the map with a couple of percent filter loss and post compressor flow restrictions.
If you were only aiming for 25psi the smaller inducer is probably a better compromise as it should give lower boost threshold and better boost response and just stay inside the recommended speed line.
which is why I went with the 1150 myself, it provides enough headroom to be in risk factory case gearbox territory without having to drop boost target much even in Cooma or Goulburn or Blue Mountains around 900m altitude but still has a good compressor to turbine size ratio.
I suspect the 900 will actually drive nicer than your G35-1150 and come on more progressively.
The compressor does seem limiting on paper. With the Turblown UIM, I estimate boost will max out at around 25-26 psi, while the stock UIM might allow closer to 30 psi. This is what Mr Dahm found when he tested his G40 900.
Looking at the Dragy results leaderboard, Omar is achieving impressive times using a 68mm compressor Precision turbo paired with a larger 85mm turbine. For comparison, my current G35-1050 has a 68mm compressor and a smaller 62mm turbine. Omar kindly shared switching from a 7685 to a 6885, resulted in no loss in power but gains in efficiency and response. That insight supports my decision to choose the G40-900 over the G40-1150. Time will tell how the G40-900 performs.
If the G40-900 underperforms, there’s always the option of switching to the newly announced V2 G-series turbos from Garrett. I will share the results good or bad!
i am wondering if Slides hacked into my computer as i had almost a a duplicate post but decided to defer on it until i had a bit more time.
my takeaway on the G40-900 is that it will be interesting to see the net on it.
i say net as there are some serious plusses and minuses.
the plus is the 50 Trim. the G40-1150 is 65 Trim.. both numbers are at ends of the spectrum.
BIG DIFF.
lower Trim favors spool and handicaps top end. the 900 map clearly reflects this.
900 efficiency is really good to 500 rotary rwhp/70 pounds, then rapidly falls off before hitting choke at 600/81. max flow is at 22 psi and 58% efficiency. higher efficiencies (68) along w slightly lower flow (79) are .available at 35 (!) psi. all of this is right at the choke line and you don't want to visit that neighborhood.
in contrast, the same compressor wheel with the 71 inducer generates 70 pounds/500 hp at 78% efficiency, 80 pounds/600 at 77.5% efficiency at 22 psi boost.
i did a run 10 days ago which proved the map spot on. 22 psi. 628 rwhp (this includes 3% from the meth portion of my AI), 405 ft pounds tq at 8134.
nice but there's more:
"efficiency" is all about IAT. since 95% use a thermistor to find IAT the community is resting comfortably. there is no such thing as a 'fast acting thermistor." i currently log both a thermocouple and a Delphi fast acting thermistor. the thermistor is log pretty flat line whereas the thermocouple registers accurate at 4 samples per second. the logs look quite different.
my point in beating this dead horse is that compressor map efficiency matters. temps out of an inefficient compressor pre intercooler can reach 400 F when you are in the area north of 20 psi. if you have a really good intercooler subtract approx 130 F. if you are running WM at around 600 cc/min subtract another 40 F.
returning to my recent run: at 8134 rpm, 22.1 psi, 628 hp the intake air out of my turbo before the intercooler was 241.7 (!) and 70 F into the motor. 70 freaking degrees into the motor at 600. wowser. part because of a really good intercooler, low drag system and meth, but a significant add was the very efficient turbo.
my old EFR 9180 would be at 62 efficiency. i was routinely seeing close to 400 F...
the logs on my "fast" thermistor show max reading of 67 while the thermocouple shows max 111. if i had been running the 9180 at 600 and 400 F out of the turbo... minus 140 and minus 50 IAT would have been 210 F whereas the thermistor would have been showing something very similar to my recent run, around 70.
inefficient turbos break motors when combined with fictional IAT reports.
moving on w re to the 900:
the biggest concern i have is the non divided hotside. i will be very interested to see how that effects the positive (Trim) factor. we are running the equivalent of two piston motors. when one piston/rotor is at TDC the other is at BDC. if left undivided one impulse enters the largeish housing with no other pressure impulse to help. so it gets divided by 2. in theory this should be a big deal for any 2 rotor or 2 piston motor. i don't understand why Garrett doesn't offer the same 1.06 divided for the 900... maybe they do but it isn't on the site nor shown as an option at Full-Race.. hopefully Garrett will make a divided hotside. (my 1150 is 1.06 divided.)
my CPR manifold keeps divided through the wastegate.
Last edited by Howard Coleman; Jan 5, 2025 at 05:26 PM.
When I looked at the V2 options it looked like G40-1150 or a jump to the G45-1500 or 1600 was probably still the best balanced compressor/turbine couples for our use in terms of efficiency, possibly a little bit of boost threshold available on the higher flowing smaller GXR inducers if you are willing to give up a few percent pumping efficiency in the top end.
i am wondering if Slides hacked into my computer as i had almost a a duplicate post but decided to defer on it until i had a bit more time.
my takeaway on the G40-900 is that it will be interesting to see the net on it.
i say net as there are some serious plusses and minuses.
the plus is the 50 Trim. the G40-1150 is 65 Trim.. both numbers are at ends of the spectrum.
BIG DIFF.
lower Trim favors spool and handicaps top end. the 900 map clearly reflects this.
900 efficiency is really good to 500 rotary rwhp/70 pounds, then rapidly falls off before hitting choke at 600/81. max flow is at 22 psi and 58% efficiency. higher efficiencies (68) along w slightly lower flow (79) are .available at 35 (!) psi. all of this is right at the choke line and you don't want to visit that neighborhood.
in contrast, the same compressor wheel with the 71 inducer generates 70 pounds/500 hp at 78% efficiency, 80 pounds/600 at 77.5% efficiency at 22 psi boost.
i did a run 10 days ago which proved the map spot on. 22 psi. 628 rwhp (this includes 3% from the meth portion of may AI), 405 ft pounds tq at 8134.
nice but there's more:
"efficiency" is all about IAT. since 95% use a thermistor to find IAT the community is resting comfortably. there is no such thing as a 'fast acting thermistor." i currently log both a thermocouple and a Delphi fast acting thermistor. the thermistor is log pretty flat line whereas the thermocouple registers accurate at 4 samples per second. the logs look quite different.
my point in beating this dead horse is that compressor map efficiency matters. temps out of an inefficient compressor pre intercooler can reach 400 F when you are in the area north of 20 psi. if you have a really good intercooler subtract approx 130 F. if you are running WM at around 600 cc/min subtract another 40 F.
returning to my recent run: at 8134 rpm, 22.1 psi, 628 hp the intake air out of my turbo before the intercooler was 241.7 (!) and 70 F into the motor. 70 freaking degrees into the motor at 600. wowser. part because of a really good intercooler, low drag system and meth, but a significant add was the very efficient turbo.
my old EFR 9180 would be at 62 efficiency. i was routinely seeing close to 400 F...
the logs on my "fast" thermistor show max reading of 67 while the thermocouple shows max 111. if i had been running the 9180 at 600 and 400 F out of the turbo... minus 140 and minus 50 IAT would have been 210 F whereas the thermistor would have been showing something very similar to my recent run, around 70.
inefficient turbos break motors when combined with fictional IAT reports.
moving on w re to the 900:
the biggest concern i have is the non divided hotside. i will be very interested to see how that effects the positive (Trim) factor. we are running the equivalent of two piston motors. when one piston/rotor is at TDC the other is at BDC. if left undivided one impulse enters the largeish housing with no other pressure impulse to help. so it gets divided by 2. in theory this should be a big deal for any 2 rotor or 2 piston motor. i don't understand why Garrett doesn't offer the same 1.06 divided for the 900... maybe they do but it isn't on the site nor shown as an option at Full-Race.. hopefully Garrett will make a divided hotside. (my 1150 is 1.06 divided.)
my CPR manifold keeps divided through the wastegate.
Thanks for the insights!
Ait's is def a concern but so far soo good with wmi. My current G35-1050 setup is running a Vband turbo housing 1.21ar and single entry HKS exhaust mani/wg which will be retired shortly. I appreciate its not the most efficient setup yet still providing very respectable 100-200 times.
I will be running the T4 twin-scroll 1.19 ar fully divided turbo and exhaust mani. The divided turbo and exhaust housings will ensure that each rotor’s exhaust pulse is isolated, preventing interference and maintaining consistent energy delivery to the turbine. This should help with max turbo response and overall efficiency of the rotors to breath independently.
According to Garrett's G40 900/1150 T4 turbine data the 1.19 ar divided housing flows the most.
This pretty much wraps up the updates for this year.
