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I should have been more specific. Base pressure of 43.5(or 45) +30 PSI boost with a 1:1 Pressure regulator. After speaking with ID Injector and FueLab, they also added in Differential Fuel pressure. When speaking with them, in order to achieve 75psi rail pressure(45+30psi for boost), you also have to add the same 30PSI on top of the 75 as the differential pressure that the pump outputs or 105PSI pump pressure. Maybe I understood them wrong, but I asked several times to make sure?
Regarding hot fuel, I would agree and assume that as you raise the PSI demand on the pump, it increases heat. I dont necessarily know what the efficiency range of the FueLab pump is directly, but when I spoke to their tech he was not concerned at running the pump at 105PSI. Link to Tech specs below. Show that the pump has a max of 125PSI. This is the same pump that Rob Dahm used in his recent Tii ~700rwp video.
Differential fuel pressure is just the difference between rail pressure an manifold pressure with the goal being to equal your original base pressure. Pumping losses and efficiency aside, no need to start adding a second 30 psi buffer on top of what you've already described unless ID is just baking that in as their boilerplate efficiency loss number to CYA.
What sparked the issue are a few things that I received different answers to. I try to do a lot of research and understand things before a purchase. And as I am planning a big single turbo build fuel components are a major area.
Referencing the ID charts for the 1700cc(slope/Offset/Pressure), I went down a rabbit hole. I received a few answers that the 1700cc injector will always be 1700cc in flow--IE mechanically limited. Second set of answers said they scale up with boost, which is the opposite of the former comment. What didnt make sense on the former were car likes Howards. Backing into fuel calculators on Ethanol for ~700rwp, he would need roughly 12,000cc of injector to hit that power level, but his injectors are (2)-1350cc and (4)1700cc. So how does his car not lean out? Or Rob Dahm with his FC Tii running (2) 1700 and (2) 2600.
I am specifically looking at the 1350 and 1700CC from ID. After speaking with ID and Aaron from FFE(former ID guy) they all suggested these injectors as they are all metal construction. Being that I will have to run Ethanol exclusively or blend of it plus pump, I like the idea of all metal components(as opposed to some plastic) as Ethan can wear out plastic. Both also mentioned that the 2600cc, since plastic over time with exposure to Ethanol, will start to expand slightly.
So I decided to call ID and FueLab to seek out an answer.
In looking at their chart(https://injectordynamics.com/injectors/id1700-xds/) the 1700cc at ~43.5 and flows 1725cc. The fuel pressure on the far left is the pressure at the rail, so at a base pressure of ~45+ 30PSI of boost, the 1700cc injector at 75 total PSI actually drives the 1700cc injector 2285cc. This was what the ID technical team explained to me. Thats when he mentioned having the pump driver 30 extra PSI over the target fuel rail pressure. This could very well be my misunderstanding, but I asked him to clarify that and reiterated that I needed to effectively drive the pump at 105PSI if my target rail pressure was 75PSI(including boost).
As stated above it could be a big CYA and overkill or I could have completely misunderstood the ID Tech I spoke with as I was in a little disbelief. Ultimately if it is just in fact a huge CYA, then the pump will have a lot of headroom and be way more than I need. Which for our temperamental rotaries, I am ok with having too much firepower. lol
Erich, while i understand that it is easy to fall into the add the boost twice it really doesn't work that way.
if you decide to run one bar static (43.5 psi) and you need to figure deliverability you just add the boost (30) and go to 73.5 on the fuel pump graph.
let's do 600 rw rotary hp
600 takes 80 lbs per minute of air
let's use 10.5 AFR ( and keep it simple w 100% gasoline)
7.62 pounds per minute of gas
7.62/6.35 = 1.2 gallons per minute or 4542 cc per minute of 100% gasoline to make 600 rw rotary hp. since your want to run a max 85% duty cycle and there is around 20% slippage due to lag you need around 6700 Gross injector.
if you go to Ti Automotive's Hellcat chart at 75 psi you find 120 gph which is 7570 cc per minute. at 13.5 V. clearly one Hellcat pump will do 600 rotary on gas. line and filter restriction are less than you might think... Kenne Bell has all the numbers in their Excellent fuel pump tech section.
In looking at their chart(https://injectordynamics.com/injectors/id1700-xds/) the 1700cc at ~43.5 and flows 1725cc. The fuel pressure on the far left is the pressure at the rail, so at a base pressure of ~45+ 30PSI of boost, the 1700cc injector at 75 total PSI actually drives the 1700cc injector 2285cc.
This is almost correct, but you've got the injector flow part wrong. The fuel pump needs to make 75psi pressure, but the injector still sees 45psi difference between its entrance (fuel rail at 75psi) and its exit (manifold at 30psi). 75psi fuel rail - 30psi manifold pressure = 45 pressure difference across the fuel injector. So the flow rate will be 1760cc/min for each injector.
I asked him to clarify that and reiterated that I needed to effectively drive the pump at 105PSI if my target rail pressure was 75PSI(including boost).
This is correct, the fuel pump would need to make 105psi if you want the injector to flow 2285 cc/min. 105psi fuel rail - 30psi manifold pressure = 75psi pressure difference across the fuel injector.
There's actually a very good demonstration of fuel pressure and manifold pressure in an old Rob Dahm video. It might also help to understand the reason why the fuel pressure won't always match your base pressure, because the fuel pressure regulator is bypassing different amounts of fuel depending on the manifold pressure.
The fuel pump tapping out is proving difficult to push more boost. That being said playing around with the fuel injection timing and a bit more tweaking I managed to reduce injector duty cycle on average by 5.6% on the primaries and 6.2% on the secondaries. Even after pulling out nearly 6% fuel out of the boost areas this did not reduce the burden required off the fuel pump. It was still nose diving despite both primaries and secondaries injectors demanding 6% less fuel on average. The peaks as noted above are much higher like 8% less fuel demand from the pump.
I had to do this comparison because my last post absolutely proves the time loss due to the manual shift plus time lost to get back to desired boost. 3rd gear shift when 100% throttle (21.2psi boost) is 53.964 4th gear shift when throttle back to 100% (ony 10.7psi ) is 54.431 The total time loss is 0.467 plus an additional 0.291s to get back to 21psi to match the boost in 3rd before shifting to 4th.
In summary, a DCT would be faster than a stock FD box everytime not to mention there would be zero loss of boost. DCT time for the same would be approx 6.09 - 0.467 ~ 5.62s for a 100-200kph and thats not taking into account being off boost. That being said.....i have a stock fd manual and in reality the valid draggy run is a 6.09s. Its close but no cigar, the draggy is a cruel mistress and denies me the 5s pass yet again.
Not all good news - The clutch slave cylinder tapped out after this 6.09s run and the clutch pedal stuck to the bottom. I had to force it back up and pump it 10x (performance issues ) to be able to drive back home. That concluded any further tuning for the night. It was disappointing as I was in the zone and only had 0.1s left to find in a rather conservative tune ha! . There will be no further 100-200 testing for at least a couple weeks to carry out some much deserved maintenance.
The plan in no particular order
Hopefully the above will take a couple of weeks and I can get back to 100-200 testing on the street port.
I have a couple more secret upgrades which will be revealed soon. Hopefully these cycle of life improvements should improve overall efficiency of the setup.
^^ on an OE box that will be teeth stripping death
wrt gear shift time lapse, you’re overlooking the lag contribution of the open V-band manifold and matching large A/R turbine housing
which would still exist with a DCT box.
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Surely the Link has flat shift logic? If it sets a limiter close to next gear engagement it shouldn't ****** any harder than a normal shift but come back on boost a touch quicker.
Surely the Link has flat shift logic? If it sets a limiter close to next gear engagement it shouldn't ****** any harder than a normal shift but come back on boost a touch quicker.
It does have flat shift and Gav aka beytek mentioned it would work with the stock box. I haven't got the additional inputs on the G4+ to test this theory but will have 16 additional inputs on the new G4X to be able to set up flat shift. I'll likely need some input from Adam and see if he thinks it will work with the stock FD box.
The fellow FD owner with the G42 curently with the fastest 100-200 on pump fuel is going to setup flat shift and rolling launch on his dog box. Hopefully get some input on how well the setup works.
DCT would be the way to go, perhaps Race only can confirm if there is boost loss in between shifts but one of the reasons for the ECU swap to the newer g4x was to get the additional inputs to run flat shift (if possible with stock box), rolling launch, boost by gear and launch control
It does have flat shift and Gav aka beytek mentioned it would work with the stock box. I haven't got the additional inputs on the G4+ to test this theory but will have 16 additional inputs on the new G4X to be able to set up flat shift. I'll likely need some input from Adam and see if he thinks it will work with the stock FD box.
The fellow FD owner with the G42 curently with the fastest 100-200 on pump fuel is going to setup flat shift and rolling launch on his dog box. Hopefully get some input on how well the setup works.
DCT would be the way to go, perhaps Race only can confirm if there is boost loss in between shifts but one of the reasons for the ECU swap to the newer g4x was to get the additional inputs to run flat shift (if possible with stock box), rolling launch, boost by gear and launch control
The flat shift logic setup is specifically to allow factory syncro boxes to get the best return to delivery without damaging them.
If you are considering changing to a modern box I'd probably go to the 8 speed auto, I think Gav has his driving well now. I think Omar may not have had some downshift lockout logic enabled before his last overrev failure.
yeah, I haven’t been on top of this thread lately; forgot about him talking about the turbo change from a while back and also hadn’t considered the ecu having the flat shift torque management feature, so that’s my ignorance having just glanced over the list of proposed upcoming changes and not put a lot of thought into it.
honestly though, I bit my tongue about knowing the fuel system is inadequate, but still out there hammering on it looking for a couple of hundredths of a second …
I suppose a failing clutch system can occasionally be a blessing in disguise.
.
The flat shift logic setup is specifically to allow factory syncro boxes to get the best return to delivery without damaging them.
If you are considering changing to a modern box I'd probably go to the 8 speed auto, I think Gav has his driving well now. I think Omar may not have had some downshift lockout logic enabled before his last overrev failure.
It was always the plan to set up flatshift with the new ECU. Hopefully it works well, time will tell.
Ahh, the ZF8 paradox. I agree it is a good box (I've got it in my daily driver and noticed no power loss during gear shifts with Dragy). BMW changed from DCT to adopt the ZF8 for their current M cars speaks volumes about their confidence in the ZF8 but we all know this was primarily cost-driven. While DCTs offer faster shift times compared to ZF8 transmissions, the difference might be imperceptible to most drivers. Here's a ballpark comparison:
DCT: Around 100 milliseconds, faster if you can tune it well.
ZF8: Around 200 milliseconds
That being said, previous experiences with DCTs (in models like the M3, M4, M5, 992 GT3 and GT4 RS) have left a lasting impression on me regarding driving engagement, speed and precision where as the ZF8 feels lacklustre. It's close but no cigar, lacking the direct feel of the DCT.
For the FD, I've decided to opt for a DCT in the near future. I agree tuning the DCT will pose a learning curve, I'm not overly concerned in that regard as couple years ago I didn't know how to map a car let alone tune an RX7 but now I can manage to map and run multiple low 6-second runs draggy verified pulls. Plus there is enough knowledge and support out there and on this forum to get the DCT running like it belongs in the FD. Would Porsche put a ZF8 autobox in their legendary GT3 cars? never....because the DCT aligns with the 911 GT3's focus on performance. I feel the RX7 is similar in this regard and deserves a performance focused gearbox. End of the day it comes down to personal preference...
Run no BOV or disable/keep closed = no boost loss
also, no-lift shift with a tilton clutch flow control valve to dampen the shock
consider a Feed bigger bore clutch cylinder for extra volume
This is my 2 rotor on 27PSI E85 DCT 6885, I think theres a 4.90 on the same boost but I will wait till the track tomorrow . Will also be trying more boost tomorrow if I don't break anything
This is my 2 rotor on 27PSI E85 DCT 6885, I think theres a 4.90 on the same boost but I will wait till the track tomorrow . Will also be trying more boost tomorrow if I don't break anything
This is my 2 rotor on 27PSI E85 DCT 6885, I think theres a 4.90 on the same boost but I will wait till the track tomorrow . Will also be trying more boost tomorrow if I don't break anything
Well done mate and a brilliant result. You could have given me a week of enjoying second place.
Fingers crossed your runs go well. Looking forward to a 4s run. If you dont mind me asking how fast is the DCT shifting? is this something that is measured or captured within the logs?
I need a couple of things to add you to the Draggy leader board.
1. Draggy overlay video....everyone going in top 3 need to provide one. Same as me in the previous post and Nath had to do the same plus the draggy report. You've already done the draggy report so not to worry unless you go even faster ha!
Owner - Omar aka Raceonly.
Model - RX7 FD3S?
Gearbox - BMW F80/82? 7 Speed DCT
Modifications - Turbo Make and model?, boost used (27psi) - 13b engine port type?
for e.g
G35 1050 - 22.5 psi - XL Street Port
Bhp/HP/PS - ?
Fuel - E85
Aux Injection - any wmi etc being injected etc?
The above data makes it easy to document your build so its easily comparable in the below format against other builds on the Leaderboard.
Well done mate and a brilliant result. You could have given me a week of enjoying second place.
Fingers crossed your runs go well. Looking forward to a 4s run. If you dont mind me asking how fast is the DCT shifting? is this something that is measured or captured within the logs?
I need a couple of things to add you to the Draggy leader board.
1. Draggy overlay video....everyone going in top 3 need to provide one. Same as me in the previous post and Nath had to do the same plus the draggy report. You've already done the draggy report so not to worry unless you go even faster ha!
Owner - Omar aka Raceonly.
Model - RX7 FD3S?
Gearbox - BMW F80/82? 7 Speed DCT
Modifications - Turbo Make and model?, boost used (27psi) - 13b engine port type?
for e.g
G35 1050 - 22.5 psi - XL Street Port
Bhp/HP/PS - ?
Fuel - E85
Aux Injection - any wmi etc being injected etc?
The above data makes it easy to document your build so its easily comparable in the below format against other builds on the Leaderboard.
Are you guys using a GoPro to overlay footage?
Ill see if I can get the go pro going tonight at the drags
Owner - Omar aka Raceonly.
Model - RX7 FD3S
Gearbox - BMW F82 7 Speed DCT with H7 DCT Adaptor
Modifications - Precision 6885 Next Gen 1.28 T4, boost used (27psi) - 13b REW - Tic Tac bridge - pump E85
MaxxECU
620HP at 28PSI last time I had it on the dyno(it seems to show lower numbers then I would normally expect but that's what it shows)
Ill see if I can get the go pro going tonight at the drags
Owner - Omar aka Raceonly.
Model - RX7 FD3S
Gearbox - BMW F82 7 Speed DCT with H7 DCT Adaptor
Modifications - Precision 6885 Next Gen 1.28 T4, boost used (27psi) - 13b REW - Tic Tac bridge - pump E85
MaxxECU
620HP at 28PSI last time I had it on the dyno(it seems to show lower numbers then I would normally expect but that's what it shows)
No we do not use GoPro for dragy overlays. We use the draggy app on our phone to record the video overlay. I've got 2 magnets in the FD which hold the phone when i want to safely capture a video without worry of the phone falling off etc.
I use a delkin heavy duty mount to a heavy duty magnet. Once the phone is on it won't come off. That's my setup to capture the draggy runs for validation etc.
Nath uses a magnetic phone holder like the below for his runs. Good enough to validate a 100-200 run for the leaderboard with the draggy report.
1. Go to the Draggy main screen "Go" and click on the video option on the top left. This will open your camera within the draggy app.
2. Select record button when you are ready to complete the 100-200 run. The draggy app will capture the video overlay for you.
3. Once the run is complete go to "Me" tab on the bottom right of the app and click on the video option.
4. Select the video you just captured and select next and then you can click the export button. That will send the video to your phone gallery from the draggy app.
5. Trim the relevant part of your run.
No we do not use GoPro for dragy overlays. We use the draggy app on our phone to record the video overlay. I've got 2 magnets in the FD which hold the phone when i want to safely capture a video without worry of the phone falling off etc.
I use a delkin heavy duty mount to a heavy duty magnet. Once the phone is on it won't come off. That's my setup to capture the draggy runs for validation etc.
Nath uses a magnetic phone holder like the below for his runs. Good enough to validate a 100-200 run for the leaderboard with the draggy report.
1. Go to the Draggy main screen "Go" and click on the video option on the top left. This will open your camera within the draggy app.
2. Select record button when you are ready to complete the 100-200 run. The draggy app will capture the video overlay for you.
3. Once the run is complete go to "Me" tab on the bottom right of the app and click on the video option.
4. Select the video you just captured and select next and then you can click the export button. That will send the video to your phone gallery from the draggy app.
5. Trim the relevant part of your run.
New parts arrived for some well deserved and some overdue maintenance.
New braided brake lines (nothing whatsoever wrong with the old project mu lines but just thought as the system will need to be flushed and bled may as well get new lines as the car is faster than its ever been).
New clutch line - this is going back as it was not required because i forgot it already had a braided clutch line from the MC to the clutch slave cylinder plus the length of the line was the wrong length for my application.
New clutch slave cylinder - turns out the current one was just fine and the issue was elsewhere..see below.
New oil service was well overdue. I change oil every 3-4 months but it's been nearly 6-7 months since the last change.
The eagle eyed among you will notice 2 walbro fuel pumps. My mate with a 1000whp R35 GTR had 2x walbro 450 high pressure pumps lying around as spares for his setup and when he found out I was running out pump with the Bosch 044...lets just say he offered them up immediately to help me get into the 5s range sooner rather than later. Although, not the original plan it seems i wont have to worry about running out of pump...like ever!!
My mate Kev come out to get the fd back on the road and carry out the much needed overdue maintenance.
Needs some TLC to the body work and ideally a full respray to be perfect again.
When the old clutch slave cylinder came out..Kev confirmed this connector failed and oil was weeping out of there. Thats why my clutch pedal was loosing pressure, turns out the slave cylinder was fine.
I completely forgot there was a Tilton flow valve already installed on the clutch line...this explains a lot about driveline reliability. Over 300+ 100-200 runs and counting. I did wonder if it was luck the that got me to 300+ 100-200 runs...turns out the little flow valve was doing it's job and doing it well.
Kev made up a new line and connector...but we decided to use the new clutch slave cylinder anyways as there will be more 100-200 abuse incoming.
Overall a successful day carrying out routine maintenance.
New clutch slave cylinder and brake lines installed and brake fluid flushed and pressure bled. The pedal feel has come back to life. This maintenance was well overdue.
Oil and filter changed. We went through the oil and filter with a fine toothcoombe to ensure nothing untoward going on inside the engine and happy to report...all is well. No apex seals, bearings etc etc found in the oil! Boring stuff just oil in the oil! lol
Didn't have time to swap in the dual pumps...but this will be happening in a couple weeks. Thinking I need to address the rest of the fuel system at the same time. I will add a radium primary fuel rail with Asnu 1500cc injectors. I am currently at 90%dc at a 24psi peak with 4700cc of fuel flow. Should be up to 6000cc in a couple of weeks and dual pumps than back to 100-200 draggy testing.
It's had really good use over the past months and you can tell with the brake dust being baked on the wheels.
The paintwork is still looking great considering it was in for a paint correction over 18 months ago .
My mobile detailer completed the below.
Pre wash Snowfoamed Safe washed Deep clean on the TE37 SL's including barrels Dried Hand glaze applied Topped off with a coat of Soft99 Kiwami to lock in the shine Tyres dressed Exterior glass polished
Should be more slippery through the air with all the dirt and grime gone [img]data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7[/img] Difficult to capture how good it looks on a phone camera...but it looked like glass when Ben was done with it. The paintwork came back to life.
Keeping these wheels clean will be a challenge, but hey, that's the sign of a car that gets driven and enjoyed! Still cant believe I landed a set of TE37SLs for my FD, absolutely buzzing. These wheels have always been a dream. Sometimes I cant believe the fd has such a sweet wheel and tire setup - TE37SLs and Cup 2s, doesn't get much better than that for performance driving!
04-19-24, 12:27 PM
) is 54.431
) to be able to drive back home. That concluded any further tuning for the night. It was disappointing as I was in the zone and only had 0.1s left to find in a rather conservative tune ha!
.
