Texas Mile FD
10-31-13, 06:27 PM
#27
The fuse burn is expected. You fuse current rating is too small for a Walbro 416 using 13.5 volts let alone the 16.0 or 17.5 volts you talk about using, take a look at the manufacturer datasheet on that part. Also are you taking your Boost-a-pump out of spec? Apparently they have 20.0A and 40.0A models.
i doubt there is a problem aside from too small of a fuse protecting a cricuit drawing more amps than the fuse was intended to carry.
my suggestion wasn't to bandaid some sort of problem, it was a fix for insufficient amperage. bigger pumps simply require more juice. if this fuse was protecting the BAP iirc the module bypasses and transfers battery voltage instead of the increased modulated voltage, if it was protecting the circuit feeding power to the BAP then it simply is too small.
Last edited by RotaryEvolution; 10-31-13 at 06:33 PM.
10-31-13, 08:17 PM
#28
All out Track Freak!
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I didn't even pick up on the fuse condition being burned which clearly is some hot current for some reason or another but as Howard said it should be an easy fix.
Anywho definitely sucks and when I 1st saw the thread I was hoping to see a crazy fast run.
Anywho definitely sucks and when I 1st saw the thread I was hoping to see a crazy fast run.
11-01-13, 04:44 PM
#30
i eventually did get to the start line for my first pass and pulled off a clean start. my first gear is a 2.66 V the stock fd which is around 3.5 so it, being more like a normal second gear, can bog. no bog and an instant 9000 in first and second. shifted at 8800 in third and fourth.
11-01-13, 07:36 PM
#31
Derwin
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Apparently under load the current draw of the pumps was much higher than specified by the mfr.
Really sad to read of the failure seems we never see FDs competing anymore. Best of luck in next years event.
11-01-13, 07:52 PM
#32
the current draw is specific to battery voltages, the BAP obviously increases the efficiency of the pump and demand on the circuit beyond what their documentation would provide. don't go pointing the finger at walbro as not giving proper information.
the older walbros were actually quite forgiving in their amp draw compared to most other manufactures, but i have not really tested this 490 pump yet so it may be an amp hog compared to the others. an amp draw tester would give definitive answers to how much the pump actually needs at the increased voltages beyond trial and error.
the older walbros were actually quite forgiving in their amp draw compared to most other manufactures, but i have not really tested this 490 pump yet so it may be an amp hog compared to the others. an amp draw tester would give definitive answers to how much the pump actually needs at the increased voltages beyond trial and error.
Last edited by RotaryEvolution; 11-01-13 at 07:57 PM.
11-02-13, 08:40 AM
#35
Racing Rotary Since 1983
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sure, there are a number of possible culprits.
the pump is new and given the flow numbers is the biggest single pump i have had in the car. i did have an Aeromotive Stealth previously which does not flow quite as much as the Walbro. given the fact there aren't any free lunches my guess is a larger fuse might be high on the list of fixes. i have sent Walbro an email re fusing as well as Geoff at Full-Race and should have an answer soon.
another culprit could be a partially blocked pump filter. Luke has had this occur numerous times when converting to E85. apparently E85 pretty much scours the tank and anything but tank ends up in the filter. i do also have a proper (stainless steel screen) Aeromotive filter downstream from the pump.
as far as the Boost A Pump, i have run a BAP since 04 at 20% gain with no problems. my pump is hardwired thru an insulated stud and does get 13.3 V. it gets 16.0 V (only) in boost. i have never had a pump failure w the BAP. the BAP does have it's own fuse and relay.
i was pretty comfortable w re to the engine for the event as we had really beaten on it on the dyno. sure, it isn't quite the same but fuel pressure, for example, held steady thru a number of 5 gear foot on the floor runs to 8800 in five gears. on my first run the motor ran over 9000 in the first two gears. we may have touched 9000 on the dyno.
boost was off the spring ( 20) in first and second, 24 in third, 26 in 4th and 24 in fifth. i reached 5th at 160 and the motor pulled fifth strong for a second before i got out of it as i was limited to 165 on my first run.
i do plan to take a look at the car sunday (tomorrow) and will post what i find.
on a side note there has been questions as to how the T56 shifts at high RPM. my T56 comes from an F body (Camaro 99) and has a 2.66 first which is really great as well as close ratios thru 4th. on the dyno shifting into fifth required a short pause to allow the syncros to catch up. at the Mile all the shifts worked as fast as i could move the lever. love the trans. also love my Quartermaster double disc clutch.... only 2000 pounds of springs, in the car for 4 years w the original discs. flawless.
there's lots of additional prep work to do on the car before my next run but i am so impressed w how the FD ran around 165. we had a 15-20 gusty crosswind and i didn't feel a thing while others remarked it was pushing their cars around. the ECU does offer just about anything re to active response measures such as fuel pressure delta and we just hadn't gotten around to it. car prep was somewhat rushed and we did our best w the time we had.
i am excited about getting back to Texas. i looked at the Ohio Mile which is one thousand miles less one way but the rules are crazy for 200 mph and it looks like a lot of old school Hot Rod Mag stuff. been there done that a million years ago. i really like the mix of cars at Texas.
howard
the pump is new and given the flow numbers is the biggest single pump i have had in the car. i did have an Aeromotive Stealth previously which does not flow quite as much as the Walbro. given the fact there aren't any free lunches my guess is a larger fuse might be high on the list of fixes. i have sent Walbro an email re fusing as well as Geoff at Full-Race and should have an answer soon.
another culprit could be a partially blocked pump filter. Luke has had this occur numerous times when converting to E85. apparently E85 pretty much scours the tank and anything but tank ends up in the filter. i do also have a proper (stainless steel screen) Aeromotive filter downstream from the pump.
as far as the Boost A Pump, i have run a BAP since 04 at 20% gain with no problems. my pump is hardwired thru an insulated stud and does get 13.3 V. it gets 16.0 V (only) in boost. i have never had a pump failure w the BAP. the BAP does have it's own fuse and relay.
i was pretty comfortable w re to the engine for the event as we had really beaten on it on the dyno. sure, it isn't quite the same but fuel pressure, for example, held steady thru a number of 5 gear foot on the floor runs to 8800 in five gears. on my first run the motor ran over 9000 in the first two gears. we may have touched 9000 on the dyno.
boost was off the spring ( 20) in first and second, 24 in third, 26 in 4th and 24 in fifth. i reached 5th at 160 and the motor pulled fifth strong for a second before i got out of it as i was limited to 165 on my first run.
i do plan to take a look at the car sunday (tomorrow) and will post what i find.
on a side note there has been questions as to how the T56 shifts at high RPM. my T56 comes from an F body (Camaro 99) and has a 2.66 first which is really great as well as close ratios thru 4th. on the dyno shifting into fifth required a short pause to allow the syncros to catch up. at the Mile all the shifts worked as fast as i could move the lever. love the trans. also love my Quartermaster double disc clutch.... only 2000 pounds of springs, in the car for 4 years w the original discs. flawless.
there's lots of additional prep work to do on the car before my next run but i am so impressed w how the FD ran around 165. we had a 15-20 gusty crosswind and i didn't feel a thing while others remarked it was pushing their cars around. the ECU does offer just about anything re to active response measures such as fuel pressure delta and we just hadn't gotten around to it. car prep was somewhat rushed and we did our best w the time we had.
i am excited about getting back to Texas. i looked at the Ohio Mile which is one thousand miles less one way but the rules are crazy for 200 mph and it looks like a lot of old school Hot Rod Mag stuff. been there done that a million years ago. i really like the mix of cars at Texas.
howard
Last edited by Howard Coleman; 11-02-13 at 08:43 AM.
11-05-13, 11:43 AM
#38
Wastegate John
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maybe i didn't make myself clear... i knew the engine was history a couple of seconds into 4th gear.
"overkill is better, 30a fuse with paralell twin 30a relays even to a single pump."
appreciate the constructive advice... of course the key will be diagnosing why the fuse blew which will not be difficult.
howard
further, my motor is fine. it has the same compression as when i put it on the trailer for Texas. for some reason i don't understand, after the second run the motor spun over w the starter like it had zero compression. no power impulses on the starter. at that point i decided there was no plan B and the jig was up.
yesterday i swapped in a new fuse and the motor fired up and gave me good numbers. so no blown motor on E85.
howard
yesterday i swapped in a new fuse and the motor fired up and gave me good numbers. so no blown motor on E85.
howard
Yup, you drove 2600 miles and did not check anything, what a waste. You may have been able to make more runs had you checked things in texas. I guess you are so used to blowing motors that that was the most probable problem for you and assumed it was blown.
You should have a stainless filter sock on whatever pump you use in the tank.
Did you change your fuel lines to something rated for ethanol when you converted to e-85?
Last edited by RENESISFD; 11-05-13 at 11:47 AM.
11-05-13, 11:53 AM
#39
the problem is not so much the compatibility but the age and usage of the hose, i wouldn't switch fuels and use the hose that ran gasoline for a few years and then switch to E85.
in tank requires special submersible hose which should have been provided with the pump(mentioned above), past that most high pressure fuel hose will work fine for E85 but i would change them more regularly.
most of the crap in the sock is probably just varnish from the tank that gasoline allows to settle on the walls of the tank, E85 strips the tank clean and requires cycling and a few filter changes to become settled in place and ready to run. at the end of the day you can't switch to E85 and expect it to be a seamless transition, you must break in the fuel system or use all brand new components from the start. ideally a fuel cell eliminates most of the issue.
in tank requires special submersible hose which should have been provided with the pump(mentioned above), past that most high pressure fuel hose will work fine for E85 but i would change them more regularly.
most of the crap in the sock is probably just varnish from the tank that gasoline allows to settle on the walls of the tank, E85 strips the tank clean and requires cycling and a few filter changes to become settled in place and ready to run. at the end of the day you can't switch to E85 and expect it to be a seamless transition, you must break in the fuel system or use all brand new components from the start. ideally a fuel cell eliminates most of the issue.
Last edited by RotaryEvolution; 11-05-13 at 11:57 AM.
11-05-13, 05:12 PM
#40
Howard, being an old timer like me, you probably are aware of this. You comment on how the car handled the crosswinds made me think of it. As I recall, which may be flawed, back in the day the white Racing Beat FD flipped at Bonneville from aero induced forces when it went over 200mph. The following year it was painted black and set records. Seems like a Car & Driver writer was a driver or maybe just sponsorship for the FD.
I suspect you are wise to aero forces, or was it a blown tire like the Hinson ZO6? Anybody correct my info so I don't start any new internet misinformation.
Best wishes and good luck nonetheless, Philip
I suspect you are wise to aero forces, or was it a blown tire like the Hinson ZO6? Anybody correct my info so I don't start any new internet misinformation.
Best wishes and good luck nonetheless, Philip
11-05-13, 05:20 PM
#41
Racing Beat built several RX-7s for land speed record attempts both at El Mirage Dry Lake Bed in CA, and the Bonneville Speedway in Utah, Nevada. Three different Racing Beat RX-7s set new land speed records over a 25-year span. An ill-fated attempt in 1993 resulted in a harrowing airborne ride for car designer/driver Jim Mederer at speeds approaching 220mph! The car was repaired and in 1995 returned to the salt flats and established a new land speed record of 242.005 MPH. As a testament to the extraordinary accomplishments of the Racing Beat RX-7 race vehicles, these land speed records have stood the test of time for over 25 years!
Here's the correct info form RB's site
Here's the correct info form RB's site
11-05-13, 07:55 PM
#42
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"You just put it on the trailer and did not check anything?"
"i knew the engine was history a couple of seconds into 4th gear"
i do apologize for for not making myself clear. first off, the only thing i knew in 4th gear was i had no power. i did not know the engine was blown or not blown. so my statement was not correct.
as to packing up... after i rolled to a stop i removed my helmet and earplugs so i could better hear and i cranked the motor. there was zero compression. we hadn't brought along a spare motor so the game was up. i did think at that time the motor was toast. it wouldn't have made a difference to go snooping around for a blown whatever.
or so i thought at that time.
i have since concluded that a completely dry motor shows little compression. i did what amounts to a fuel cut at 6500 rpm. the motor did rpm a bit as i tried to get it restarted while rolling out thru the mile at 132. there was no fuel, no lube (Benol) going thru the motor.
when i returned home and switched out the pump fuse the injectors relubed the interior of the motor and it was clear the compression was back. the motor appears to have suffered no damage whatsoever.
my (speculative) conclusion:
totally dry rotary motor... little compression
normal rotary motor w fuel and prelube... compression
opinions welcome.
i did inspect the return line hose at the tank. it is approx 4 inches long, an OE item, and does not appear to be degraded... yet. i will replace it w a proper hose.
as far as Bonneville/RacingBeat etc... i was close to the guy that built the turbos (3) for that car. they lost it shifting into fifth or sixth. it broke loose. 3 rotor, 3 turbos, dry ice on the intercoolers etc.... a beast. the primary problem is the salt and the tires you need to run. there is little traction on salt.
in addition vehicle fly-ability goes up almost exponentially w the speed. they were going really fast.
as to the Hinson Corvette. my friend Ray and i had driven all night to see the Texas Mile a couple of years ago. when we arrived we drove to the fast end of the track and walked thru a bunch of haulers for a first view. i looked left down the track and saw a silver Corvette just clearing the 3/4 mile marker.
it stopped rolling and started to fly. nose up. left front up more than right front. it veered slightly off the track and did a half barrel roll and landed on its roof. it bounced off the dirt and did another half barrel roll and landed on its wheels in a pile of fiberglass.
i turned to Ray and said... "i want to do this."
the twin turbod corvette had run over 200 the prior day and they had turned the boost up so they were over 1000 hp on the run.
which blew a right rear tire lifting the left front and away they went.
problem was drag tires... they are now verboten.
i really had fun at the Mile and while overall it turned out to be a bummer it was worth it to run over 160 in 3/8 of a mile. i truly think my car can run 200. we were very conservatively tuned. central to it all will be some sort of different logging platform. maybe the new Surface Pro 2...
racing for 22 seasons i had my wins and losses. the losses didn't get me down as long as i learned something. i learned a few things on my first trip to Texas.
howard
"i knew the engine was history a couple of seconds into 4th gear"
i do apologize for for not making myself clear. first off, the only thing i knew in 4th gear was i had no power. i did not know the engine was blown or not blown. so my statement was not correct.
as to packing up... after i rolled to a stop i removed my helmet and earplugs so i could better hear and i cranked the motor. there was zero compression. we hadn't brought along a spare motor so the game was up. i did think at that time the motor was toast. it wouldn't have made a difference to go snooping around for a blown whatever.
or so i thought at that time.
i have since concluded that a completely dry motor shows little compression. i did what amounts to a fuel cut at 6500 rpm. the motor did rpm a bit as i tried to get it restarted while rolling out thru the mile at 132. there was no fuel, no lube (Benol) going thru the motor.
when i returned home and switched out the pump fuse the injectors relubed the interior of the motor and it was clear the compression was back. the motor appears to have suffered no damage whatsoever.
my (speculative) conclusion:
totally dry rotary motor... little compression
normal rotary motor w fuel and prelube... compression
opinions welcome.
i did inspect the return line hose at the tank. it is approx 4 inches long, an OE item, and does not appear to be degraded... yet. i will replace it w a proper hose.
as far as Bonneville/RacingBeat etc... i was close to the guy that built the turbos (3) for that car. they lost it shifting into fifth or sixth. it broke loose. 3 rotor, 3 turbos, dry ice on the intercoolers etc.... a beast. the primary problem is the salt and the tires you need to run. there is little traction on salt.
in addition vehicle fly-ability goes up almost exponentially w the speed. they were going really fast.
as to the Hinson Corvette. my friend Ray and i had driven all night to see the Texas Mile a couple of years ago. when we arrived we drove to the fast end of the track and walked thru a bunch of haulers for a first view. i looked left down the track and saw a silver Corvette just clearing the 3/4 mile marker.
it stopped rolling and started to fly. nose up. left front up more than right front. it veered slightly off the track and did a half barrel roll and landed on its roof. it bounced off the dirt and did another half barrel roll and landed on its wheels in a pile of fiberglass.
i turned to Ray and said... "i want to do this."
the twin turbod corvette had run over 200 the prior day and they had turned the boost up so they were over 1000 hp on the run.
which blew a right rear tire lifting the left front and away they went.
problem was drag tires... they are now verboten.
i really had fun at the Mile and while overall it turned out to be a bummer it was worth it to run over 160 in 3/8 of a mile. i truly think my car can run 200. we were very conservatively tuned. central to it all will be some sort of different logging platform. maybe the new Surface Pro 2...
racing for 22 seasons i had my wins and losses. the losses didn't get me down as long as i learned something. i learned a few things on my first trip to Texas.
howard
11-06-13, 08:44 AM
#46
sorry it didnt end up as you hoped but atleast the motor is good . and atleast for next time you will know . to check the fuse , or fix the weak link ,
had you replaced that fuse . who's to say it wouldnt of gone again during your next run , and you not been so lucky but yeah I had issues with my fuses I had started with a 20 amp , and ended up with a 40 amp . which has worked well for me . doesnt heat up , gives good passage . and matches the 40 amp relay .
after this I'm debating running a dual relay system .
had you replaced that fuse . who's to say it wouldnt of gone again during your next run , and you not been so lucky but yeah I had issues with my fuses I had started with a 20 amp , and ended up with a 40 amp . which has worked well for me . doesnt heat up , gives good passage . and matches the 40 amp relay .
after this I'm debating running a dual relay system .
11-07-13, 09:56 AM
#48
Senior Member
Regarding aero...
Last October I ran my '94 with '99+ front splitter and no rear wing, no front undertray (my home-made P.O.S disintegrated on my ~150mph licensing run). Ride heights ~24.9" all around to the top of the wheel opening arch. 245/40-17 front, 275/35-18 rear Michelin Pilot SuperSports.
I did four runs, ~150mph license run, 183.8mph full-bore 2nd run, 177ish run with front air opening totally blanked off (ran hot, pulled timing, stupid move!), 184.8mph the following morning.
Above ~145mph, the back end started feeling a bit less than well-planted. As speed climbed, the back end started moving around a bit, requiring steering correction :0 Not a lot of steering correction, but enough to be quite unnerving.
If/when I go back, I'll lose the front splitter (downforce at the very front of the car unloads the rears) and get a front undertray and rear diffuser. I'm also going to get a '99+ rear wing for track use, but hope to get the car stable at high speeds without it.
Anyway, glad to have been on airport runway tarmac rather than on salt!
Last October I ran my '94 with '99+ front splitter and no rear wing, no front undertray (my home-made P.O.S disintegrated on my ~150mph licensing run). Ride heights ~24.9" all around to the top of the wheel opening arch. 245/40-17 front, 275/35-18 rear Michelin Pilot SuperSports.
I did four runs, ~150mph license run, 183.8mph full-bore 2nd run, 177ish run with front air opening totally blanked off (ran hot, pulled timing, stupid move!), 184.8mph the following morning.
Above ~145mph, the back end started feeling a bit less than well-planted. As speed climbed, the back end started moving around a bit, requiring steering correction :0 Not a lot of steering correction, but enough to be quite unnerving.
If/when I go back, I'll lose the front splitter (downforce at the very front of the car unloads the rears) and get a front undertray and rear diffuser. I'm also going to get a '99+ rear wing for track use, but hope to get the car stable at high speeds without it.
Anyway, glad to have been on airport runway tarmac rather than on salt!
11-07-13, 10:55 AM
#49
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so we called Mazda, and they told us to put coils, plugs and wires in it, which seems dumb, but whatever they were paying for it.
so we replaced the ignition, fired it up, and its running on 2 rotors, let it warm up, retest compression and both rotors were over 8, so engine magically is fine.
so yes, the contents of the combustion chamber, and the way the engine is/was running makes a huge difference in compression.
ps, i'm glad you made it to the track this year, and if the only casualty was a fuse, that is ok too, better that than upside down!
11-07-13, 11:21 AM
#50
Wastegate John
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^ There is no doubt that a dry motor will cause low compression readings. The oil film in the motor is used to supplement the seals (apex and side seals) sealing ability. Some of the sealing properties rely on the differential pressure between the rotor chambers to improve the seal. If the sealing action is subpar due to lack of an oil film then the sealing issue is magnified.