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Cool! Yeah, that's exactly what I did with the flapper valve.
I'll probably run it like that at this weekend's event and then try the Hydramat after that with another S2 housing I picked up.
Originally Posted by trackjunkie
Thanks for the idea of drilling out the trap door hole and modifying the trap door so it can swing out farther. I just took my pump out again to do the mod. You can see the difference between the original 5/16 hole vs the new 3/8" hole with the two different drill bit. Also snip a little off the trap door so it can swing back more. And also removed some material outside the tube so more fuel can get in.
Well I was just repeating what someone else posted about fixing flow in their pump module for a turbo RX8 without having any direct experience with it myself, but there are so many aftermarket parts and kits available now it doesn’t seem that difficult to resolve. At the same time I can relate to being burned out over having to work through another custom solution. Wish I had the SM rules to work with rather than my own custom deal for DSP. Sorry for your troubles, hope you can get it resolved soon.
It has nothing to do with being burned out. It's more that I don't really want to take the car down for long periods of time and miss events. I need to get the thing sorted out before September which feels right around the corner.
Well you have an autox car that won’t stay running in a corner. It seems like the priority would be to fix that asap over anything else no matter what it takes money or time-wise. If you go to the next event and it’s still not running right then what did you gain over skipping the event to instead work on it to fix the problem? Just the same, wishing you a quick and easy solution.
I guess you missed the posts where I outlined what I had done to address the problem?
i wonder if that rubber bladder is larger than the oem basket and if we could put the oem basket inside it, that would hold more fuel for the long corners. just have to punch a little hole at the bottom of the rubber bladder for the siphon inlet. and use their check valve for the bladder.
my thought was to somehow increase the volume of the oem basket by adding material to the side to it make it higher.
Last edited by trackjunkie; 07-10-2019 at 07:29 AM.
i wonder if that rubber bladder is larger than the oem basket and if we could put the oem basket inside it, that would hold more fuel for the long corners. just have to punch a little hole at the bottom of the rubber bladder for the siphon inlet. and use their check valve for the bladder.
my thought was to somehow increase the volume of the oem basket by adding material to the side to it make it higher.
I thought about trying to rig up a basket with a larger volume than the stock one as well but it seemed like a lot of work with questionable benefit. The whole mess still has to fit through the hole in the tank. Based on my fuel flow testing with the drilled-out feed hole, I think that should solve my problem (which contrary to what Mark thinks is not losing fuel flow in sustained corners - it's draining the basket during long periods of WOT).
If not, I did pick up that Hydramat and a Radium jet pump. The stock jet pump is pretty anemic at pulling fuel from the passenger's side of the tank. Ultimately the "right" answer is to remove the stock tank and put a small fuel cell on the passenger's side, where the tank was. But that's going to involve enough work and money and engineering that it's not feasible to do until the season is over. Worst case, I can just run the rest of this year with the tank full - the car runs fine like that. It's 90lbs of extra fuel but it's central to the car and down low, so I suspect the performance impact is pretty minimal.
Well I ran the car at an autocross today, and even down below 1/4 tank I had zero fuel delivery problems. Data logs show no loss in fuel pressure and I didn't have any cutting out. So for now I'll call that a success.
That great to hear. So the only thing you did was enlarge the hole for the check valve at the bottom since last time right? I have high hopes now that my fuel starve issue is fixed. Thanks to you and Mark for all the input. I have a race this coming weekend and will see, although this track doesn't have the left U turn like the track that was giving me problems.
Last edited by trackjunkie; 07-14-2019 at 07:48 PM.
I enlarged the hole and trimmed the top tab of the flapper so it can open farther. Same thing you did I think.
The course we ran today had two big WOT sections (well, for autocross) followed by long, sustained left hand turns. Pretty much the worst possible scenario for fuel starve in my car, and it had no issues whatsoever.
Hello everyone! I just read through this thread and it has sparked a couple of questions. First is are you experiencing and issue related to wheel hop since your installation of the Ronin kit? Second on the Ronin web site they picture a round tubular weld in section that appears to replace the stock front cross section of the subframe. John is this a revision to the kit you purchased? If it is a revision would you mind sharing any thoughts about the recision.
If anyone else has thoughts please share. Thank you
Hello everyone! I just read through this thread and it has sparked a couple of questions. First is are you experiencing and issue related to wheel hop since your installation of the Ronin kit? Second on the Ronin web site they picture a round tubular weld in section that appears to replace the stock front cross section of the subframe. John is this a revision to the kit you purchased? If it is a revision would you mind sharing any thoughts about the recision.
If anyone else has thoughts please share. Thank you
I believe I have all the pics of my ronin kit in here. It's not tubular.. That is the FD setup that is tubular. The Ronin setup for the RX-8 consists of a plate that bolts to the rear cover of the 8.8 and a front brace that welds to the front of the RX-8 subframe.
No issues with wheel hop at all and I've done probably 50 hard launches at full boost. Though I'll add that in my experience, wheel hop is usually caused by bushing compliance. I don't have any rubber bushings left in the car, so there's really no compliance left to contribute to wheel hop.
Thank you John. I just revisited the site and i see what you mean about the FD kit. It seems i selected the wrong kit when I was looking for the RX8 kit.
So today I hopefully wrapped up my fuel system improvements. I should have taken pictures, but honestly I wasn't sure it was going to work and I'm only a couple days away from leaving for Oscoda so I just wanted to be done.
I ended up cutting the bottom off of the S2 fuel pump assembly about 2" from the bottom. That allowed me to fit the Hydramat to the bottom of the fuel pump and it's nicely pressed into the bottom of the tank.
Discovering that my factory siphon wasn't working, I picked up the Radium venturi pump unit. I fitted it to the side of the S2 fuel cup so it's discharging directly onto the Hydramat. It is fed from the return line from my fuel rail. I put everything in the tank on that side and opened up the passenger's side fuel pickup and let the fuel pump run. Sure enough the fuel level on the passenger's side drops pretty quickly! The Radium pump seems to be extremely effective. Of course this is a best-case situation since I wasn't running the engine (so all the fuel was being returned) but it should still work fine.
With the hydramat I was actually able to completely drain the fuel tank. The car is 2,668 with no fuel at all in the system. The battery and mount I'm running is a pretty heavy Braille and all together it's 17lbs. With a 2lb lithium battery, that would take me to 2,653 with no fuel. I think I can lose 25lbs in brakes which would get me to 2,628, but that sort of ends the low-hanging fruit. There are a few pounds here and there with mounts and brackets I made too heavy, and my splitter is heavier than it needs to be compared to a carbon fiber version of the same thing. Maybe a couple pounds totally gutting the hood and trunk lids. I totaled everything up and could maybe get to 2,600 with zero fuel. Pretty comfortable with where the car is and I'll certainly look for opportunities to save weight in the off season. For now I'm just happy the fuel system issues are hopefully behind me for good.
Yeah, aluminum exhausts are a horrible way to save weight. The exhaust is pretty much the lowest part on the car and very centrally located. And aluminum is a terrible material for exhaust due to the thermal and vibration stresses involved.
my friend Aaron Shoe has aluminum exhaust on his 550 whp evo, you guys probably know him from nat solo. he had to reweld it once or twice but its cheap and easy weight reduction, when there's nothing else you can remove from the car.
my friend Aaron Shoe has aluminum exhaust on his 550 whp evo, you guys probably know him from nat solo. he had to reweld it once or twice but its cheap and easy weight reduction, when there's nothing else you can remove from the car.
I know Aaron well, and I like Aaron. Having said that... his car is broken more than it runs. My goal with this car has always been to overbuild it so it finishes every event.
It will hold up better on non-rotary engines, but both heat and frequency harmonics on a rotary will kill one in short order, especially NA. The wall thickness plays into how long it will last, but also the weight. Usually the ones that don’t break are made out of thicker wall and not as light as you might suppose. The bottom line is it can be just as light and 100% trouble free using light gauge (18/20 Ga) stainless steel.
I agree, there's just no good reason to do it. Thin-gauge stainless is the way to go if you have the welding skill. I put a pretty big and heavy muffler on the car because I like my cars on the quiet side. I could save some weight there but again, it's central and low, lower than I could even put ballast, so I don't really see the point.
I'm also looking at options for a lighter alternator. The one on the car is a Mazda 3 unit, and it's not light. I also had to modify it quite a bit to get it to clear the steering shaft. I suspect I could find something that could save a bit of weight at the front of the car but with the fab involved it'll be an offseason project.
ok, you guys win :D
i'm saving up to do Ti exhaust on my car. i got thick gauge stainless pipes now and it's heavy AF. and i only have two resonator on it. mine doesnt have to supper quiet, i wear ear plugs in the car. i want to delete the PPF also but im hesitant because it protect the carbon drive shaft also. being on track there's all kinds of stuff that could get kicked up from the tires or chance of going of track.
Well even the original RX8 alternator is only 13 lbs and it’s likely within a pound or two of that. Can’t recall anything lighter than 6 or 7 lbs. So there’s only so much to be gained, but being forward whatever you can lose would be good even if mounted low like on the MZR.
Your build is a bit chubbier than I would have expected based on where my DSP build is looking to be. If my car had a boost **** I might not be fretting on grams either though, heh ...
Ti is not really the best bet either and will cost more than using even 20 Ga T321
Well I wasn't fast this weekend, but at least I finally found the core problem I've been fighting with fuel delivery - voltage drop to the fuel pump. At full boost and >70psi fuel rail pressure, the pump can't supply the necessary flow unless it has over 13.5V and through the factory wiring it's not getting that. To finally nip this issue and to hedge against any fuel delivery problems I'm converting to a dead-head setup at the fuel rail and putting a Radium surge tank in the trunk with a pump directly wired off the battery through a relay, and using the in-tank pump to keep the surge tank full.
Even though I was slow, I managed to squeak out a second place finish and the car was a blast.
07-09-2019, 06:31 PM
