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Does the battery disconnect completely close all power off? How does the car like that when you power it back up? I am considering something similar for storing during winter, but have read a couple of horror stories now on people letting their batteries drop very, very low in storage and the car won’t restart. It made me question if it’s even safe to store a Lexus with no power. Thoughts?
Overall, Its fine. I have tested it a couple ways and there isn't any determent other than the transmission relearning, which from my testing doesn't have any effect on anything like putting power down or shift speeds. (this was all based off GPS accelerator data and shift speed mathematics from signals I pipe to the data logger) I also consistently checked for the first few months that stored codes do not go away and that it wouldn't create any that weren't there before, all good there too.
The ONE thing I am keeping my eye on is the steering ECU coming off learned 'center'. I honestly don't think that has anything to do with the kill switch, more than likely its my rack- and for my uses doesn't matter to me since I only drive the car 'pedal danced'.
Ok it's been a little bit because I have been busy with other cars and work but I decided to tackle a job i had been thinking about for a while. I have found in my testing that if I am in G load of -1.4 for over 5 seconds and dont have over 3/4 of a tank I can starve the fuel system. This isn't that big of a deal, I just need to remember that I need to keep it topped up at the 2 local tracks where I will see these conditions. BUUT I still wanted to work on a solution, things like this annoy me.
I first drained the fuel tank so I could get a good look at what I was dealing with. The OEM tank is a saddle tank with a 1/2 of the volume sitting in a tank on the passengers side and 1/2 of the fuel sitting on the drivers side it has a single low volume pump that feeds the cam driven high pressure DI and PI pumps up at the motor. The way the factory pumps the fuel over the saddle from one side to the other is with a venturi "jet pump". Its a no moving parts system that uses the pumps main suction as a venturi effect to siphon flow through a hard pipe pick up on the passenger's side. Its drawn up and over into the drivers side where it's sucked into the sock then the integrated filter, then pushed to the fuel rails. It's a quite compact and clever system and it actually works very well, even with a high G capable car i don't suffer any fuel cuts or starve outside of a very specific circumstances.
There are a few ways to tackle this kind of thing one would be to re-engineer everything and start from scratch to solve the problem and the other would be to just try and piggy back on top of the OEM engineering to fill in the gaps where needed.
Once I had the tank empty I had to see what I was working with as far as my ability to mod or add to the OEM tank.
Once apart I learned a few things about the system. 1 the service holes on the passenger side are extremely small, were talking like an inch and a half max and doesn't offer much room to be able to work to add an additional pump or fuel sock. 2. The main pump service hole is a bit bigger but the OEM fuel pump hanger box has a few key features integrated into it that make engineering a replacement a bit more difficult.
I came up with two blank sheet solutions and sketched them out, the first one was how to do it with an external draw pump with an integrated hydramat.
This set up made sense for a few reasons but was lacking in a few other areas. Mainly would require a custom fuel tank topper disk to be cut and fitted with a a fuel float locator. I would also need to run an external Fuel Pressure Regulator and filter.
The second solution I came up with was to use the stock pump housing, fuel filter and FPR but run everything into an external sump system. This is a great solution and would 100% solve all fuel starve issues.
The down sides are the amount of parts required (2 pumps) and how much complexity is being added in the additional lines and fittings outside of the tank. This is something to be considered. The OEM manufacturer spent millions and millions on R&D to make a pretty bomb proof fuel system. I like the peace of mind that the fuel delivery in my car is all stock. My personal rule is if I modify anything in a racecars fuel system outside of the tank, I have to wear a fire suit. This is something i don't want to do in my ISF if I can help it. I dug around in my million dollar box of fittings and found almost everything i need but decided I'd think it over for a few days.
After weighing all of the options I decided to try and OEM + system. I would leave everything outside the tank stock and see if there was a way to help fuel pick up at the pump itself. I've use a Holley Hydramats in other racecars in the past with great results so I wanted to see if there was a way I could adapt one in my ISF. If you don't know what a Hydramat is check out this quick demo.
It's basically a super wicking sock that can draw up unaerated fuel when only touching a very small corner into the liquid. I ordered a new fuel pump and fuel filter as a matter of course. Mine didn't actually look horrible but this is always a good "while you're in there" type of thing.
For the pump I ordered an AEM 50-12210 its literally a direct bolt in pump to OEM with a slight boost in the LPH flow rate. This would be a good bump in the suction to increase draw rate of the siphon jet pump.
I next disassembled the fuel hanger too see if there would be a way to adapt a hydramat. You can see in the picture below the oem pick up location with the orientation in the car noted.
The pump sits directly on top of the sock and draws fuel in through the holes in the housing the submerged sock requires fuel feed from the marked area below Threes small holes, the one large hole, the dot representing the fuel pressure/main valve bleed-off and the curved aero representing the jet pump draw.
All this is good under most conditions but you can see how a hard left hand corner would load the fuel against the fuel tank where gas would have a hard time reaching the pick up.
I poked around and took some measurements and found a hydramat that is made for an 11mm pump socket. It turns out that that is exactly what we need to clip into our fuel pumps There were a couple size mats available with the pump connection size so I made cardboard templates out of each and begin test fitting what would work best in the ISF
After a lot of measurements to get centers I found that the 8x3" is the perfect size to fit inside the OEM baffled pick up tank.
Now that I had my mat I would just need to modify a few different parts of the OEM housing to get the sock to work, it was all pretty straight forward. I first trimmed the main valve and retainer clip off of the pump retainer clip.
so now they were both divorced from the fuel pump retainer.
Then i sized the new hydramat clip and trimmed the clear retainer disk on the new fuel pick up.
Once that was done I clipped it all together on the new filter with the new pump.
Next I moved onto trimming and smoothing the housing itself.
I took an extra hour or so and used a jeweler's file and Dremel to smooth out all the edges on the housing. It took some awkward angled work but when I was ready I added new o-rings, the float and hooked up the new siphon pump. I attached the Hydramat retaining disk into the pump and clipped the whole shebang together. There is no weight resting on the mat itself because its suspended by the retaining ring on the bottom and hanger mount on the top of the fuel filter housing, just like stock, but better.
You can see how much more of a foot print the new Hydramat has. The fuel return dump, overflow relief, siphon pump outlet also all fall directly on top of the exposed sock and should act to keep the fuel rails filled. I booked a track day at the offending track for early next month, I plan on running some session purposefully low on fuel, hopefully I can report back that it fixed the issue I was having on the long left handers.
Ive also done some other stuff but ill make a post on that later
Any comments on the amount of swarth in the tank after all these years of operation? Pretty clean or significant filth?
I assume you read the New Car Features to better understand the OEM design? It will be interesting to see if the OEM subtank design continues to work as intended. The designers made sure the fuel pump was alway well bathed in fuel to manage heat and consequently wear on the fuel pump. From looking at the design, it would seem you could also put in a pump with a significantly greater flow and achieve a similar result. I know the AEM is rated a little higher than OEM, but if you could find a suitable pump with 30-40% higher volume it would keep the subtank level higher than the OEM pump, and starvation would be less likely. The only downside is a larger capacity means more current draw, and I'm not sure how the system will like something like that. The NCF specifically states the pump is a low current design to reduce power consumption.
In the later model engines, they dispense with the fuel return line from the HPFPs by putting the spill valve in front of the pump instead of after. They also run a higher target pressure. But the rest of it looks just like the older design. Pity they couldn't have done that in the first place. It would help minimize fuel heating - lots of Supra guys found this out the hard way with bigger pumps and lots of fuel getting cycled through the fuel rail at low load. Pretty difficult to tune your engine with widely variable fuel density.
Any comments on the amount of swarth in the tank after all these years of operation? Pretty clean or significant filth?
I assume you read the New Car Features to better understand the OEM design? It will be interesting to see if the OEM subtank design continues to work as intended. The designers made sure the fuel pump was alway well bathed in fuel to manage heat and consequently wear on the fuel pump. From looking at the design, it would seem you could also put in a pump with a significantly greater flow and achieve a similar result. I know the AEM is rated a little higher than OEM, but if you could find a suitable pump with 30-40% higher volume it would keep the subtank level higher than the OEM pump, and starvation would be less likely. The only downside is a larger capacity means more current draw, and I'm not sure how the system will like something like that. The NCF specifically states the pump is a low current design to reduce power consumption.
In the later model engines, they dispense with the fuel return line from the HPFPs by putting the spill valve in front of the pump instead of after. They also run a higher target pressure. But the rest of it looks just like the older design. Pity they couldn't have done that in the first place. It would help minimize fuel heating - lots of Supra guys found this out the hard way with bigger pumps and lots of fuel getting cycled through the fuel rail at low load. Pretty difficult to tune your engine with widely variable fuel density.
So this was exactly the idea behind my first blank sheet design. I had a Hydramat affixed to the bottom of the tank with the venerable Bosch 044 being used as an external pump. This design takes the pump out of the fuel and allows it to be put in a finned pump cooler right next to a finned fuel filter cooler. A major added benefit would be the ability to place the FPR right before the return to the tank and have it directly power a new Raduim Engineering siphon pump that is larger than the OEM one (draws more pressure). One of the down sides of the OEM set up is the siphon jet pump is run off of the lift side, which effectively uses the fuel stream directly out of the pump to create the suction to power the jet pump, this works fine, but is just a controlled fuel leak that reduces pressure out of the tank overall. By using a beefier pump externally you get benefits in all categories. Increased fuel flow via better external pump, increased return to the tank which means flow to the Hydramat, cooler fuel, and the ability to run an aftermarket jet pump. I can draw it out if you'd like.
The down side to all this is the amount of fittings and stuff I would need to have outside the tank, increased noise and the need to build a custom fill plate with 2 -6an bulkheads and a fuel float attachment point. Not hard but when looked at together with the external fittings count I back burnered it. Version 2.0 of this idea is using the oem pump to lift into a surgetank. This is what the RR racing kit does, it adds a second fuel pump submerged in less than a gallon of gas and puts the FPR on the exit of the surge tank. This layout is built into the radium surge tank and you wont get the added benefit of using the return pressure to power the siphon pump. Its not a BAD system at all, and is many steps above the stock. You can do a hybrid hybrid system where you divorce the surge tank, FPR and pump but you start to add mega complexity and there is no way of getting away from 2 pumps when using a surge tank.
After weighing it out the downsides to any surge tank set up were cost, amount of fittings and surge jug outside the tank. Also multiple pumps and not achieving all the benefits for the effort. After chewing on it a while I decided that as far as fuel modifications go "If you're in for a penny you're in for a pound" 12 external fitting vs the 23 external fittings was still going to be external fittings. I settled on my v0.5 approach that i posted yesterday.
As far as the electrical needs of the other systems I drew up a simple relayed circuit using the oem pump 12v to power a fused source directly from the battery.
We'll see how mine does. All in the maintenance parts like the filter and pump on my version were by far the most expensive part of the upgrade. I still may do my optimum version in the future, we'll see.
As far as the tank sludge my car was very very clean. The pick up sock was dirty and had embedded metal shavings but the internal filter was only a dark brown. All in all i've seen worse.
I agree with the move to try your V0.5 setup first. I've run Hydramat in the past and been impressed. But conversely, it can only do so much. My experience has been, if you had a 5s threshold before, it'll move up to 7s. And instead of 3/4 of a tank, it'll happen at 1/2 tank instead. f that's enough for your courses, high five. If not, well, you got better? Though it'll be interesting to see how the fuel pump change factors in as well. Worst case, then you got to phase 2.
You're thorough so I suspect you already checked, but on paper those AEMs (or was it the aeromotive stealth...my memory is foggy now) draw a ton of current. I'm running duals in another project car and had to run some serious wire.
On a completely different subject, you mentioned pedal dance. I finally made it out on track w/ the OSG diff this past weekend. Unfortunately it rained the whole time, so I was apprehensive about letting it go full nanny off. However, my experience thus far is that the...low VSC mode (hold down button) plays surprisingly well w/ the OSG. Such that, if it triggers an event, I don't know that I was far enough over I wasn't losing time regardless. From a time perspective, maybe little/no benefit to going completely off. Have you experimented back and forth since putting in your OSG? What's your take? I only had 2 dry sessions (on Pirelli DH, but zero aero and stock weight) and didn't get to test back to back with the lap timer.
Another question, how has oil pressure been with the sustained G's you're seeing?
""HARDDRIVIN I agree with the move to try your V0.5 setup first. I've run Hydramat in the past and been impressed. But conversely, it can only do so much. My experience has been, if you had a 5s threshold before, it'll move up to 7s. And instead of 3/4 of a tank, it'll happen at 1/2 tank instead. f that's enough for your courses, high five. If not, well, you got better? Though it'll be interesting to see how the fuel pump change factors in as well. Worst case, then you got to phase 2.
You're thorough so I suspect you already checked, but on paper those AEMs (or was it the aeromotive stealth...my memory is foggy now) draw a ton of current. I'm running duals in another project car and had to run some serious wire.
On a completely different subject, you mentioned pedal dance. I finally made it out on track w/ the OSG diff this past weekend. Unfortunately it rained the whole time, so I was apprehensive about letting it go full nanny off. However, my experience thus far is that the...low VSC mode (hold down button) plays surprisingly well w/ the OSG. Such that, if it triggers an event, I don't know that I was far enough over I wasn't losing time regardless. From a time perspective, maybe little/no benefit to going completely off. Have you experimented back and forth since putting in your OSG? What's your take? I only had 2 dry sessions (on Pirelli DH, but zero aero and stock weight) and didn't get to test back to back with the lap timer.
Another question, how has oil pressure been with the sustained G's you're seeing?""
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Yeah phase 2 is already on deck if this version doesn't work out 100%. I think that it should do well enough to squeak me over the line in terms of what id consider 'fixing' the issue. But again we shall see when I test it. Here's the v2.0 sketch i did real quick that in my opinion is a way better solution. Single external pump, new jet pump etc.
As far as the AEM pump current here some independent data Ive found. This is only very slightly over the oem pump current draw. I approximated the wire length and for the 14g wire Lexus uses for this pump run the OEM wire is more than enough to handle that current, so no issues there.
As far as the OSG with the traction control single press does quite well but not as fast as full driver control in my situation. I drive a bit looser than most people so I am expecting to have wheel slip and anything cutting power or applying the brakes when im trying to give it gas is always going to be slower. Remember its also looking at things like steering angle and platform yaw and brake pressure to do the calculation on how much it thinks it needs to save the driver. the FSM call it a "holistic approach" or something which just means that the nannys are all intertwined. This means that are likely also factoring in things like the max mU coefficient of the stock brake pads, tire compound wheel size etc. For me, my style and set up (aero), I find it gets intrusive, but indeed may be a good tool for another driver in another car. I follow a Japanese driver on YouTube that is pretty quick and he drives with the TC in single push. Since I'm logging all the output from the oem wheel speeds sensors I've overlayed a single push lap vs a full pedal danced lap and you can see where the ECU jumps in and kills rear wheel speed on corner exits. I can try and find that data when im back in the garage.
To be clear for anyone else that hadn't read it further up in the thread; the pedal dance without an aftermarket diff was something like 4 seconds SLOWER on a track. If you have a stock rear end, the push and hold is 100% faster 100% of the time over full pedal dance.
As far as oil pressure there are a few spots that are not great. It seems to be after long sustained rpm on straights that dive directly into a high G corner. Here is a fast section that is seeing 14.9 PSI @ 1.38G at about 5k RPM.
I gulp after seeing things like this and send the oil in for analysis, here what they had to say:
I think its a matter of the oil not draining out of the heads.Vs G loading. I'm not too sure there is much you can do about that.
As far as the OSG with the traction control single press does quite well but not as fast as full driver control in my situation. I drive a bit looser than most people so I am expecting to have wheel slip and anything cutting power or applying the brakes when im trying to give it gas is always going to be slower. Remember its also looking at things like steering angle and platform yaw and brake pressure to do the calculation on how much it thinks it needs to save the driver. the FSM call it a "holistic approach" or something which just means that the nannys are all intertwined. This means that are likely also factoring in things like the max mU coefficient of the stock brake pads, tire compound wheel size etc. For me, my style and set up (aero), I find it gets intrusive, but indeed may be a good tool for another driver in another car. I follow a Japanese driver on YouTube that is pretty quick and he drives with the TC in single push. Since I'm logging all the output from the oem wheel speeds sensors I've overlayed a single push lap vs a full pedal danced lap and you can see where the ECU jumps in and kills rear wheel speed on corner exits. I can try and find that data when im back in the garage.
To be clear for anyone else that hadn't read it further up in the thread; the pedal dance without an aftermarket diff was something like 4 seconds SLOWER on a track. If you have a stock rear end, the push and hold is 100% faster 100% of the time over full pedal dance..
Exact info I was looking for, thanks. Since you are instrumented up quite a bit, I assumed you had already investigated and trusted your findings. It was getting close enough now that it’s harder for me to discern and the pace is high enough peeking down at the light is getting tougher.
I am definitely not in the loose category. So it’s going to be less intrusive for me. Years of enduro driving. Admittedly I’m a little off pace for it. Need to get back into sprint racing for a bit to sharpen up.
So took the car out to Chuckwalla this last weekend to test the fuel system upgrades and found them to be 100% effective against the fuel starving I was seeing before. On the same corners with the same lateral G-loads/speed and revs I was able to run the tank down to a quarter and still did not experience the fuel starvation I was before adding the fuel mat. Previously the car would starve at sustained 1.3 G double apex left handers. Best of all worlds- I can keep all the fuel system mods contained within the tank and not have to run additional weight of fuel to keep the oem set up happy OR surge tank hardwear complications/weight. Since I can start a session with 1/2 the fuel, I save substantially on my 'race weight'. Half a tank less fuel comes out to (53+lbs) which will now be my default fill stopping point before sessions. Not bad for some dremel work and a couple hundred bucks in parts.
I know this is referring to a much older post. The TPMS canister, did you just put (3) TPMS sensors inside one canister, and use (1) TPMS sensor for putting air in it and leave it in the vehicle?
I know this is referring to a much older post. The TPMS canister, did you just put (3) TPMS sensors inside one canister, and use (1) TPMS sensor for putting air in it and leave it in the vehicle?
I have done it both ways. The first couple i built I used one of the oem valves with the TPMS protruding from the canister and filled it from there. Nothing wrong with that, and is actually what the valves are made for. I had glue failure from the pressure then a leaky canister (nothing to do with the oem valves). Third time I used JB weld to hold everything together and built it using an all aluminum tuner style valve as the fill valve and put all 4 TPMS valves wrapped in bubble wrap inside the canister. This was mostly done becasue I'm not a fan of the way the oem valve uses a plastic sleeve with integrated nut thingy to hold the valve in the canister. The placement of my canister puts the fill valve protruding out of the top and in harms way when loading and unloading track boxes from the car. For the 3rd and final design I opted for a stubby all metal valve and clamp-nut that could take a couple of knocks if need be. Hope it helps.
Plastic sleeve? The OE sensors have an aluminum nut and stem with a fat rubber washer. Sounds like you had something aftermarket. I was thinking if I needed to do something like this (permanent) I would remove the stems entirely and just keep the electronics module with the pressure sensor so I could make a pretty small container and not be concerned about placement or size.
This does bring to mind a solution to a problem I am having right now. I have one sensor with a weak battery (it's 13 years old) and I got new sensors to replace them, but the Discount Tire boys won't install the sensors because the inside edge of the front tires doesn't have any remaining sipes. Not only that, but they used some idiot laser device and measured on the wear bars, so they wouldn't even consider most of my tires good. I wasn't in the mood to buy new rubber when what I have is perfectly good for the summer. So now I'm thinking I just need to make a PVC device for the new front sensors and put it in the car until I'm ready to buy new front tires. That should work fine...
02-10-21, 10:30 PM
