Fuel starvation in 3rd gen--solutions?
03-15-07, 03:35 AM
#151
Originally Posted by bdagosti
What are the advantages of an intank surge setup like oorx7's, over something external like this (other than a clean install obviously): http://www.speedmachineperformance.c...uel+Surge+Tank
The problem on a street car is--where to put it? Inside the cabin is out. There isn't an obvious place to put it. There is some space around the stock fuel tank, but there's a good reason why Mazda left that space there. If you stuff a surge tank behind, in front of, or to the side of the tank, it will almost definitely burst if you have any kind of serious impact on the rear of the car. And 1.5 liters of fuel is enough to burn your car right to the ground, and maybe yourself too.
Plus, external pumps are loud.
So, if you're racing and you can gut your car, you can make a little compartment to store this away. But in a road-going FD, I'm not sure there is a good place to put it. This is one of the main reasons why I'm pursuing the in-tank solution.
I have the SARD surge tank which is really a piece of artwork. O-ring panel seal, removable AN fittings, polished...holds the second stage pump inside which helps keep things quiet and cool. Let me know if you are interested. I imported it from Japan last month.
Send me email at hyperion@obscure.org if you are interested.
-ch
03-15-07, 10:43 AM
#152
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Originally Posted by hyperion
I have the SARD surge tank which is really a piece of artwork. O-ring panel seal, removable AN fittings, polished...holds the second stage pump inside which helps keep things quiet and cool. Let me know if you are interested. I imported it from Japan last month.
-ch
-ch
03-15-07, 11:07 AM
#153
Ah, my crappy writing gets me again! What I was trying to say was that the SARD tank has a fuel pump mounted vertically in it just like the stock tank, so the pickup for the outlet tube is at the bottom of the tank. The cool thing is that since the feed pump (the one in the main tank) is running at essentially zero psi, its flow rate will exceed the pressure pump that is operating at rail pressure. Which means the surge tank is always completely full, so there is no chance for any air to get into the system, nor is there the possibility for foaming due to the rail return churning things up.
-ch
-ch
03-15-07, 02:14 PM
#154
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Originally Posted by hyperion
The cool thing is that since the feed pump (the one in the main tank) is running at essentially zero psi, its flow rate will exceed the pressure pump that is operating at rail pressure. Which means the surge tank is always completely full, so there is no chance for any air to get into the system, nor is there the possibility for foaming due to the rail return churning things up.
03-21-07, 08:56 AM
#155
Since these pics have not been posted here yet I figured I would post them here as well. This is the stock baffling in the 95+ tank.
Here is the thread I took these from. https://www.rx7club.com/showthread.p...8&page=1&pp=15
Here is the thread I took these from. https://www.rx7club.com/showthread.p...8&page=1&pp=15
03-21-07, 02:35 PM
#157
Thanks for posting these pics!
From those pics above it's pretty apparent why the factory 95 tank only partially eliminates the starvation issue. You can see that the 'fit' around the pump is pretty loose, and that the cutout goes right to the passenger's side of the tank--right where the fuel will be spilling out in a left-hand turn.
Now that I've see this, I recognize this part from the FEED instructions that HedgeHog posted earlier. I took another look at those instructions and I'm convinced now that there are pages that didn't get scanned. The manual refers to the cover, but stops before it explains how the cover and the tank are put together. If I had to guess, I'd say the FEED fuel column is essentially a bolt-on to the 95+ bucket cover.
-ch
From those pics above it's pretty apparent why the factory 95 tank only partially eliminates the starvation issue. You can see that the 'fit' around the pump is pretty loose, and that the cutout goes right to the passenger's side of the tank--right where the fuel will be spilling out in a left-hand turn.
Now that I've see this, I recognize this part from the FEED instructions that HedgeHog posted earlier. I took another look at those instructions and I'm convinced now that there are pages that didn't get scanned. The manual refers to the cover, but stops before it explains how the cover and the tank are put together. If I had to guess, I'd say the FEED fuel column is essentially a bolt-on to the 95+ bucket cover.
-ch
03-21-07, 04:33 PM
#158
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No problem. Are you refering to the second picture when you said passenger side? (Cause that was a driver side picture)
Originally Posted by hyperion
Thanks for posting these pics!
From those pics above it's pretty apparent why the factory 95 tank only partially eliminates the starvation issue. You can see that the 'fit' around the pump is pretty loose, and that the cutout goes right to the passenger's side of the tank--right where the fuel will be spilling out in a left-hand turn.
-ch
From those pics above it's pretty apparent why the factory 95 tank only partially eliminates the starvation issue. You can see that the 'fit' around the pump is pretty loose, and that the cutout goes right to the passenger's side of the tank--right where the fuel will be spilling out in a left-hand turn.
-ch
03-21-07, 04:47 PM
#159
Originally Posted by wptrx7
No problem. Are you refering to the second picture when you said passenger side? (Cause that was a driver side picture)
You can see this in the first picture.-ch
03-21-07, 05:13 PM
#160
Originally Posted by bdagosti
O very cool. So many options to choose from! I'll go whatever route my engine builder suggests (warranty) i guess. Considering my car is mainly for track use (I will only be driving on the street to get to a track), what are some Fd mounting locations for the surge tank. I'm open to both inside and outside the cabin, but I would prefer to stay away from cutting anything. If i wanted to cut my FD I would just use a Fuel Cell. Thanks again for your input.
The one FD that I've seen that used a surge tank had it mounted under the car in front of the rear suspension subframe in the space behind/under the bins behind the seats. There is a decent amount of room under there and it seems like a pretty safe place to mount such a device since there is a cover keeping debris and other stuff away from it.
03-21-07, 07:57 PM
#162
Originally Posted by gracer7-rx7
The one FD that I've seen that used a surge tank had it mounted under the car in front of the rear suspension subframe in the space behind/under the bins behind the seats. There is a decent amount of room under there and it seems like a pretty safe place to mount such a device since there is a cover keeping debris and other stuff away from it.
What I originally posted was:
Originally Posted by cant_read_posts
Hey, I don't want to sound negative, but there's a reason why there is that space in between the tank and the subframe. In the event of a significant rear collision, that space is there so the tank doesn't get crushed between the bumper and the subframe. The problem with putting a surge tank there is that it will almost definitely burst on a collision. Just my perspective,
Last edited by hyperion; 03-21-07 at 08:11 PM.
04-02-07, 07:42 PM
#164
I wanted to update everyone on the progress with the surge tank cover I designed. I'm shipping out a small number of them to beta testers this week, hoping to get some good feedback in the next few weeks. I've made a number of updates to the design that make it more effective and easier to install in both 1993 as well as 94+ cars.
Stay tuned,
-ch
Stay tuned,
-ch
04-03-07, 12:49 PM
#166
Inbox cleared! 
I've got a pretty good idea of what it costs me to make 5 of these at a time, but the price can come down if I make higher volumes. What I want to do is get some good feedback from my beta test group so that I'm convinced that this works well on all FD's.
Once that's done, I'll post a GB thread with the price. Rest assured, it will be a lot less than the Mazda cover ($250 if you can find the part number--and only works with the 94+ tanks), the FEED column ($250 and you need the Mazda cover too), or a new tank ($500+).
It will also be less expensive than DIY. I have the prototypes, pictures, material test, and scars to prove it.
Best of all, the design does not require any cutting, drilling, or modification of either the '93 or '94+ tanks!
More on this soon,
-ch
I've got a pretty good idea of what it costs me to make 5 of these at a time, but the price can come down if I make higher volumes. What I want to do is get some good feedback from my beta test group so that I'm convinced that this works well on all FD's.
Once that's done, I'll post a GB thread with the price. Rest assured, it will be a lot less than the Mazda cover ($250 if you can find the part number--and only works with the 94+ tanks), the FEED column ($250 and you need the Mazda cover too), or a new tank ($500+).
It will also be less expensive than DIY. I have the prototypes, pictures, material test, and scars to prove it.
Best of all, the design does not require any cutting, drilling, or modification of either the '93 or '94+ tanks!
-ch
04-03-07, 06:02 PM
#168
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You got my attention!
Let me know if you need any more beta testers. I can very predictably fuel starve mine on a daily basis during the morning commute....
Otherwise here's to hoping for a good cheap solution! Thanks for your sweat and scars!
BTW, I have a very early '93.
Let me know if you need any more beta testers. I can very predictably fuel starve mine on a daily basis during the morning commute....
Otherwise here's to hoping for a good cheap solution! Thanks for your sweat and scars!
BTW, I have a very early '93.
Last edited by TailHappy; 04-03-07 at 06:04 PM. Reason: add the year
04-11-07, 11:52 PM
#170
The covers have shipped out to the beta test group. One had been installed so far and I'm looking forward to some real-world feedback in the next two weeks. I want to be sure that this system works on cars other than my own...
The latest run of covers were pre-production, i.e. waterjet cut so moving to a production run is easy. As soon as I've got positive feedback I'll post info on how to order them.
Thanks for the continued interest. This is a slow process but the last thing I want to do is send something out into the community that doesn't work. My hope is to be rolling by the end of April.
-ch
The latest run of covers were pre-production, i.e. waterjet cut so moving to a production run is easy. As soon as I've got positive feedback I'll post info on how to order them.
Thanks for the continued interest. This is a slow process but the last thing I want to do is send something out into the community that doesn't work. My hope is to be rolling by the end of April.
-ch
04-13-07, 12:37 PM
#174
Originally Posted by CrispyRX7
In my group of local FD owners I would pretty much guaranteee there will be at least a half dozen buyers.
FWIW,
Crispy
FWIW,
Crispy
(including me)
