Tem120

iTrader: (5)

10 gauge . after reading up , I need to upgrade my wiring to 8 gauge .

apparently 10 gauge is only rated to 30 amps , But ironically 30 amp held , but would get warm to the touch . so i upgraded to 40 and wire / and fuse would remain cool .

8 gauge is rated for 50 amp , so it should be more then enough to run a 40 amp.

I'm guessing 40 is at the far limit for the 10 gauge .

gnx7

iTrader: (10)

Bummer to hear you were sidelined with fueling issues. My factory fuel pump wiring melted (the short stretch going into the tank) after a couple hundred miles of completing my conversion when I upgraded the fuel pump and sent 14 volts to the pump continually by going from the battery to the pump (with new relay). 10 gauge now solved that.

We went to the TX Mile in 2009 with Mike's 440ci LS powered FD and managed 196mph best. That was with 275/35/18's at all corners, no exterior mirrors, 91 octane fuel, and some tape work to improve aero. Removing the mirrors gained about 2mph. Taping the cowl area by the windshield seemed to help also. This was stock street ride height. I think with skinner front tires, more aggressive timing/fuel map for e85 we could've cracked 200mph. His engine made around 600rwhp all motor depending which dyno and achieved 140mph in the 1/4. Resleeved LS2, 4.1" stroker crank, TFS235 heads, FAST90 intake, big hydraulic roller cam.

The FD has such a small frontal area with good aero it is a natural for top speed events.

Howard Coleman

iTrader: (6)

"Bummer to hear you were sidelined with fueling issues." thanks for that.

i believe this is you at speed. i think if the nose was down you would have broken 200 easily.
i believe we are running the same transmission (T56)... you must have been in 6th gear? 200 for me will be in fifth at around 8500.



i haven't had a chance to check my wire gauge but will shortly and will probably upgrade the gauge.

how many runs did you make?

"The FD has such a small frontal area with good aero it is a natural for top speed events."

you are exactly right... 19.26 sq feet. i will try to lose another inch of ride height on my next outing.

hc

cewrx7r1

iTrader: (2)

"That was with 275/35/18's at all corners".

For a speed event that was not intelligent!

RENESISFD

iTrader: (13)

^ Although it is not the best for speed should the guy go out and buy a new wheel and tire setup for an event that really did not mean much to him.... I am sure he is aware of the drawbacks of the setup as he mentioned that to point out that the car would be hindered with that setup.

cewrx7r1

iTrader: (2)

Could have borrowed a set for the front!
Some solutions are easy, but one has to be able to analyze and think of them.

dguy

iTrader: (8)

Way to point out something that obviously knew about and all but admitted. Dick.

gnx7

iTrader: (10)

Howard-
I mapped out travel distance and you did around 1400 miles each way...... we did 1800 from the SF Bay Area down there. It was a trek that is for sure.

To really do a serious pass you need to pull out all the stops. We just ran it like it is daily driven. Pulled the mirrors to see what would happen... +2mph was the result. Even the fuel/timing map was the street setup. Obviously smaller front tires would've helped.

You should remove that rear wing... and tape the **** out of the front end, remove the mirrors, and any other drag items.

I've owned FDs for over 10 years and love this car. One of the most timeless, sexiest, lightest, most aerodynamic cars ever produced. Thank you Mazda engineers!

Howard Coleman

iTrader: (6)

i do appreciate the fact that hp to drive thru the air goes up w the CUBE of the speed.

for instance:

202 mph is 7.4% more than 188 mph

it takes, however, 24% more rwhp to do 202 V 188.

so i appreciate aero, had a bunch of ideas and one day (the last) to work it

main objective:

defeat front lift. lower frontal area and drag.

i had a new R1 splitter that i attached as i figured it had a bit more starch in it. i paneled off the brake ducts on the splitter as they remove a lot of downforce by venting air into the wheel wells. i also paneled off the oil cooler ducts. i really wanted to panel off about 2/3 of the radiator duct (the center hole) but didn't have the time. the only need for air is to the intercooler for a 30 second run.


i did lower the car to the point i had about an inch of travel before the Michelin Pilot Sport Cup tires hit the inner wheel wells. i tightened the front shock settings on my Pettit coil overs in front to reduce travel. i did not have a chance to zero out the camber.

i did remove the rear wing.

for the next event the car will get lowered almost another inch, the center hole will be significantly reduced. i will have a proper splitter which will be approx 2 inches lower and adj.

i am looking for a loggable ride height sensor for the front. in combo w the adj splitter i will hope to go thru the lights at static ride height.

my transmission, an F body T56, should also give me an edge. the F body has much close gear spacing which is critical for the small displacement rotary as well as a strong 5th gear.

here's how that looks:

........................first...........second.... ......third...........fourth............fifth

stock FD...........3.483.........2.015..........1.391... ........1...................(.719)

F T56...............2.66............1.78............ 1.3..............1.....................(.74)

GTO T56...........2.90............2.07...........1.48. ............1.....................(.80)


shifting at 8800:

stock FD...............................5104............6 072.........6336.........6336

F T56....................................5896....... ......6424........6776.........6512

GTO T56...............................6160............ .6336.........5984.........6864


should your motor like the more normal 7500 shift point:

stock FD.............................4350.........5175.. ....5400...........5400

F T56...................................5035........ 5475......5775...........5550

GTO T56..............................5250.........5400 .....5100...........5850

the numbers are interesting...

the stock FD first gear is really good for pulling stumps out of your yard and not much else.

my F body first is very close to the stock second and yet the car works fine from a stop even w my un-sprung double disc Quartermaster cerametallic clutch. in addition, first is an very usable gear on most road courses.

the stock FD trnsmission when shifted at 7500 averages 5081 rpm into the next gear while my F body is at 5458.

when was the last time you looked at your dyno sheet at 5081 RPM? maybe never. races are won by total horsepower under the curve (HUTC). i have a file of 66 dyno sheets corrected to SAE that i have accumulated. the data is 6 items from each dyno sheet. hp at 5000 to 7500 in 500 increments. i then total the hp.

hp at 5000 rpm is important. that's why my ports and manifold are designed to deliver from 5000 up.

here's a recent dyno sheet on my car. this is not an optimum number but is representative of my manifold and ports at 25 psi. (GT4094r). note hp at 5000 rpm is slightly above 400 SAE. if it was STD it would have been 10 hp more. i use the lower OE SAE rating scale.



when i did the design work for my ports and manifold a few years ago it was the 196 mph run by Mark that provided the bogie. at the time his car was posted as 550 rwhp (V8 of course). a 550 hp V8 and a 550 hp rotary do not equate. the V8 has a broader torque curve. so i figured (and still figure) that to do 200 a rotary needs a bit more than 550. 600 should do it. it also needs a broader torque curve and a closer ratio trans would be supportive.

i currently have what i need to run the number.... just a bit of fine tuning and another 1430 mile haul. we have additional hp in our setup. while the particular dyno sheet shuts off at 7800 due to loss of signal which was cured by narrowing the plug gap and therefore reducing external elec interference, the motor loves to run to 9000. we were in the low tens AFR wise and once we lean it a bit the torque curve will flatten to the east.

other turbos may be in the Jan/Feb future... the BW EFR9180 and GTX4088r look like interesting candidates. i am not looking/wanting to make more than 600. i will be comparing the three turbos for the total curve hp, not peak... as long as peak starts w a 6.

the car remains a dual prupose FD. we did remove the RB catback and just ran the Borla mid muffler for Texas. the race seat/cage can come out in an afternoon.

i still remember reading a Sports Car Graphic magazine article by Brock Yates where he took his 1965 Shelby GT350 to Watkins Glen and womped a bunch of B/P Corvettes and then drove it home... i bought a 1965 GT350 in Feb of 66 and it was a firebreather at the time.

i now have the 21st century version of what i had in 1966 and i intend to do some womping in Texas.

thanks Mazda/Garrett/Borg Warner/Pettit/Goopy/Mercury Marine/Mobil One/Autolite/Beyond Redline/and all the contributing board-members that make this site so valuable.

howard

ZDan

Texas Mile is very much an acceleration event rather than a top-speed event. Aero is important, but power is way more important, as opposed to bonneville where aero is the major driver, especially since traction is a MUCH bigger deal there.

I have a pretty accurate spreadsheet model (which I calibrated with info from the 196mph FD run), it predicted my run within 0.6mph (184.2 predicted, 184.8 achieved)!
Reducing coefficient of drag by 10% in the model increases predicted speed to 187.6mph.
Adding 10% more power increases predicted speed to 190.5mph.

For the 196mph FD, reducing drag 10% => 198.5mph, but increasing power 10% => 201mph

Basically, at these speeds in the standing mile, power is roughly twice as important as aero.

In addition to that, wider tires don't really increase frontal area much, probably don't hurt drag coefficient all that much either, particularly for a lowish car. At 5" spoiler height, the difference between 275s and 225s in terms of frontal area is 0.14 ft^2, less than 1% increase. Assuming a .01 increase in coefficient with the .14 ft^2 increase in frontal area, 275s all around probably only cost 1mph vs. 225s.

I was getting new street wheels/tires just prior to the event and agonized over tire size a bit. Was this close to getting narrowish wheels and 225/245 tires, but figured that setup was ridiculous for a 500+ hp car, so went with 8.5"/9.5" and 245/275. Mighta cost me 0.5mph...

Howard Coleman

iTrader: (6)

ZDan,

do you have a dyno sheet?

ZDan

That is quite optimistic for rwhp numbers, though! More recent dyno gave 463rwhp, 422 lb-ft.


Flywheel numbers should be in the 530hp/485 lb-ft range.

If your turbo rotary revs to 9000rpm and still makes power up there, note that you have a BROADER and less peaky powerband than my burly NA V8!
I'm making 85% peak power or better from ~4900-7000rpm, over 30% of my rev range, with peak power at 6400 or 91% of peak revs.
You're making 85% peak power or more from 5900-9000, over 34.4% of your rev range, with peak at 7400 or at 82% of peak revs.

LS engines are freaking brilliant in terms of power per $$$, power per pound, and power per size, but they don't really have particularly broad powerbands.

R_1

iTrader: (19)

All very interesting, all good ideas. Combining both will payoff. Not that adding HP is a bad thing, but I believe the payoff is greater (and cheaper) reducing drag than adding HP. Reduce the drag reduce the HP. On the flip side, add enough HP and “the mark” will be no problem.

ZDan

You believe this based on what? My analysis shows that drag is less important (roughly half) vs. horsepower in the standing mile. At Bonneville where there is WAY more space available to accelerate and where drive traction is a big issue, aero is going to be *significantly* more important. The Texas Mile is more like a long drag race. Aero drag plays a factor, but power and power/weight are more important if you look at trap speed vs. percent change in these factors.

That said, if you can knock drag down by 10% for next to nothing, of course that will help. But it's not necessarily cheap or easy to significantly reduce the drag of an already low-drag base vehicle. How much does a custom flat-bottom with integrated rear diffuser cost? Wheel fairings and/or "Moon" style discs for the wheels would also help. But we're talking a few mph or so in the standing mile. 10% more power will give twice as much more trap speed vs. 10% less drag, at least in the ballpark we're talking about here.

Rxmfn7

iTrader: (4)

Always thought doing the mile would be a fun experience, but as said I think unless you have a high powered car it probably wouldn't be all that entertaining. Doubt a ~375-400whp FD would be all that impressive. Out of curiosity, do they give an "et", or is it just all about trap speed at the mile?

ZDan

Sorry if I sound like a dick in my reply above, I can't modify it!
Let me just say that I thought the same thing, that aero mods would pay off in a big way at the Texas Mile. After studying it and modeling the run, I discovered that aero isn't as important as I had originally thought. In the end I did make a PVC front undertray to improve aero, it promptly ripped itself to shreds on my ~152mph licensing run. So much for my M.S. in Aerospace Engineering with structures emphasis :P

ZDan

They don't give an ET, just 1/2-mile speed and 1-mile speed.

A 400hp FD should be good for ~175mph in the mile.
375hp FD should be ~170.

Yeah, there are cars that are a ton faster, but still, 170mph in one mile is fooking FAST!

No excuses, just do it

RotaryEvolution

iTrader: (30)

i agree that power is more important in this event than aero. both are important but without acceleration you won't be pushing it.

even a brick on wheels can go 200mph with enough force to push it there. although that sounds stupid this is a drag race and you should be thinking of this as a rocket launching versus a glider flying. a rocket does not need to be extremely aerodynamic, the only reason they are is for stability, fuel consumption and slightly more acceleration.

R_1

iTrader: (19)

ZDan, no problem, being at work when I posted I didn’t study or think about your calculations. Ya I guess it would be difficult to substantially improve aero on the FD, and as you stated giving the target distance/target speed, HP is the key.

fendamonky

iTrader: (6)

What do ANY of the bolded businesses have to do with contributing to this site???


That's like thanking Oxygen and cold weather for making horsepower available to the masses...

RotaryEvolution

iTrader: (30)

have a tall glass.

if he wants to help promote them that is his choice, IMO people don't give businesses that do their job enough credit these days anyways.

in fact the whole of internet forums is going down the the ******* lately with the attitude people give off and i for one am going to try and be better about it from here on. why can't we go back to helping each other instead of dumping on one another... screw these feuds and personal vendettas people have been forging. this isn't a high school popularity contest to see how hard you can kick someone.

everyone has the ability to take any information given and use it or disregard it if they wish. we're a dying breed and turning into ***** isn't going to make that any better.

i believe howard can get to his goal, regardless of what i don't agree with in his calculations. constructive criticism does help us at times to better ourselves, beyond that it's just harassment.


on a side note, did my membership year tag get nerfed too? jfc.. this is what i get for being a dick.

Howard Coleman

iTrader: (6)

"Texas Mile is very much an acceleration event rather than a top-speed event."

true assuming we are talking (which we are) about a 500 hp FD rather than a 90 hp First Gen...

the 500 hp FD has excess power available over the primary resistance to acceleration which over 100 mph is aero drag. since a 500 hp FD has a terminal velocity well above 200 the question is what will be the speed before that terminal velocity is reached at the mile marker.

i find it hard to separate drag and power as they are the primary players at the end of the mile. the amount of remaining power after overcoming aero resistance (drag) determines the rate of acceleration.

aero resistance, however, can be a very dynamic element.

the FD has a drag coefficient around .30 and frontal area of 19.26 sq feet. if the front lifts 2 inches going thru the lights what do you think the drag resistance might be?

answer: probably a lot (more).

too much lift and good-by .3 drag coefficient and frontal area plus the steering gets light and camber goes positive.

too much droop and the important windshield angle goes more upright creating increased drag.

i am planning on using a Honeywell motion sensor in the front and will log longitudinal attitude. combined w an adj splitter i hope to be able to maintain the 1.5 degree forward (static) rake at speed.

as far as power i will limit it to 600. my objective is to determine what a dual purpose FD can do when optimized for the mile. i think it can do 200. my objective is not to tear my car apart to build the ultimate Texas Mile trailer queen.

admittedly, we all have different thoughts on what dual purpose is... sure i have a 4 point cage and race seat in my car. it is required to run 200 and i am not interested in putting dents in my head. both items are just bolt-ins and can be easily removed. same w the exhaust... 3 inch. not changing it, though i did lose the 30 pound RB catback.

others of course are welcome to go for higher levels of prep/speed and i will be with them all the way. i can see a properly prepped FD being able to run very high speeds at the Mile due to its aero specs.

howard

Fritz Flynn

iTrader: (263)

YEP

Dan makes a lot of sense and it's definitely true at the track. Nothing beats power for going faster in a straight line on a race track however with that said all the fun begins as soon as you hit the brakes.

ZDan

For what it's worth, with a '99+ splitter at the front of my car and no wing, with static 24.8" ride height all around, the steering didn't get light at all, quite the contrary, the front was totally PLANTED. Meanwhile the back end felt *very* light above ~160mph and I had to STEER the car gently back and forth the faster I went, left-right cycle about every 2 seconds
It was spooky enough that after my 4th run of the event (~8:45 AM on day 2) I decided not to run again.

I *strongly* recommend running more static rake by lowering the front end and raising the rear and NOT trying to achieve desired vehicle attitude with front downforce.

Front downforce via splitter acts to UNload the rear tires. You don't really want to do that!

Obviously a rear wing will add drag, so you don't want to have to do that. It would also act to de-rake the car at speed vs. no rear wing.

The problem is that even if zero front lift and zero rear lift is achieved, the aero drag by itself acts to lift the front and lower the rear of the car (on the order of ~150 lb. upload in front and download in back at 200mph). If you try to fix this phenomenon via front downforce (or lift reduction) alone, you're going to have a very planted front end and very LOOSE back end (bad things!).

WAY better to simply lower the front end and/or raise the rear enough such that it's nearer the attitude you want through the traps!

My plan for if/when I go again:
Lose the front splitter (maybe keep it handy to try it if initial runs are stable)
Install front undertray (big hole under car between Samberg radiator and front sway bar)
Install rear diffuser
Run more static rake (something like 26" rear, 24" front).

Higher spring rates won't require as much static rake. Mine are currently 11F/11R (Ohlins DFV) as of a couple of months ago, and I'm thinking of getting 13s for the front. When I ran the mile I had 9F/7R Tein SS coilovers FWIW.

585-590rwhp should be good for 200. I'm far enough away from that that it hasn't even crossed my mind to try for the big 2-0-0. But it sounds like you might have it within reach!

j9fd3s

iTrader: (3)

the road racers are putting linear potentiometers on the shocks, and logging that, you get height, but also you can use the math channel and dial in the shocks too. its pretty neat. every datalogger, and motec ecu in the world has the settings to do this already

as far as 600hp = 200mph, it should have no trouble, my friend has video and he can peg the FD speedo (~7500rpm), with only 380hp, although it may take him more than a mile.