1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

FB aerodynamics at high speed

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Old 09-02-03, 10:22 AM
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FB aerodynamics at high speed

How does the FB handle high speed? I want to have a "cheap" lightweight car and drop a TurboII motor into it, but I don't want to get squirrely at high speed. I've had an FB race car, but it only hit like 95 or so on the track, and didn't have to do any maneuvering at that speed (besides braking). And my FC seemed to do pretty good, even without the front air dam that's missing.

But I've heard that FB's don't have too hot aerodynamics, is this true?

And someone mentioned that supposedly a good kit for improved aerodynamics is the IMSA Mk1 GT3. Anyone know where I can find info on this, see it, and get prices?

Last edited by Barwick; 09-02-03 at 10:26 AM.
Old 09-02-03, 11:27 AM
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I can tell you mine's pretty damn stable at 130mph. I never took it any faster because the play in my steering wheel made for a pretty hair raising ride. Maybe after I get around to fixing that I'll finish the top speed run and go until my gear runs out at 165.
Old 09-02-03, 11:41 AM
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My stock-bodied FB has seen 117mph (calculated), and it seemed ok, but the steering was loose enough that it was a bit unsettling. That was about where it topped out (running with below stock power).
Old 09-02-03, 11:41 AM
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All that youve heared about FB's aerodynamics is bullshit. I have driven mine at high speeds (maximum speed on German autobahn, so 100% legal ) and the car was stable.
"Officially" the car would get unstable at higher speeds, because of the wing-shape. Even if this might be true, this only matters at very high speeds. This means speeds beyond what a stock FB would be capable of. Mine was doing over 200km/h (about 125mph) and didn't feel unstable. My current car goes faster, but also has a Mariah bodykit, so I can't say anything about speeds exceeding 130mph with stock body.
But the main problem with FB's is the play in the steering wheel. So if you fix that, and have a good suspension setup, there's no reason to worry.
I bet most of these people who claim unstable driving at high speeds either have a bad car (suspension and steering wise) or never drove that fast and only just say so because they heared it from someone else.
I'd say the main purpose of that bodykit is the looks of it. After all, RB did world speed record attempts with a basicly stock bodied FB. If theirs stable enough, how could our way slower cars not be?
Old 09-02-03, 12:03 PM
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looks "fairly" standard ...
Old 09-02-03, 01:10 PM
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so is there a rack & pinion replacement out there? Or are we stuck with the recirculating ball? My race car had "tight" steering according to everyone else, but I thought it was incredibly pathetic.
Old 09-02-03, 02:44 PM
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there's supposed to be one "soon" from people on the forum, but that "soon" has been forever now...
If the stok steering is not worn out, it'll be rather good, yet a bit on the slow side.
Old 09-02-03, 03:34 PM
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Haha "fairly". That Bonneville car is probably modified the **** out of! Look how low it is. No fender gaps here!
Old 09-02-03, 03:42 PM
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is it just me or does it seem weird that they set the record in 1978? wouldent it have JUST been brang to production at that time?
Old 09-02-03, 03:45 PM
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yep and what a good advert for Mazda/racing beat ... their brand new car sets a record at Bonneville
Old 09-02-03, 03:49 PM
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yea, thats what i was thinking. good promotional stuff.
Old 09-02-03, 03:59 PM
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Racing Beat made a deal with Mazda late spring of 1978 to supply them with the RX-7 for the Bonneville challenge. The car had to remain virtually stock to meet the Class E Grand Touring rules...complete interior, factory undercoating, etc. Mods were lowering the car, rims and tires, adding a roll cage and a few other safety items. Rules allowed for a PP 13B from an RX-4 with a 58mm Weber carb. Think that it could have possibly gone faster with a regeared transmission and taller final drive?
Old 09-02-03, 04:27 PM
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I think the aeros are pretty slippery, but the frontend has a tendency to lift, and the effect is exaggerated by the loosey-goosey steering.

B
Old 09-02-03, 04:32 PM
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I have had my car up to about 125mph, I didn't like it at all.

Very light front end, loose steering.
Old 09-02-03, 04:33 PM
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I had my car up to about 135 on the track this weekend and it seemed as if the front was lifting but not significantly, the largest issue was most definitely the loose steering which was a little unnerving.
Old 09-02-03, 05:09 PM
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i had my car @ 137 mph and it was unstable, my rear of the car was wabloling alot from side to side , i had to back off. BTW i have a IMSA rear spoiler
Old 09-02-03, 05:17 PM
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The RacingBeat land speed record car has a small front "chin" spoiler. If you look close you can see it. I wish I could find a place that sells it, I don't want to change the lines of the car at all, but would like for it to be a little more stable at high speed. I've noticed the front end does start to get a little light after 115mph, but it's not too bad.
Old 09-02-03, 05:24 PM
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i haven't been over 180Kmh with my FB, but at 175KMH, it was pretty stable.
Old 09-02-03, 06:36 PM
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Top of 5th gear. Felt fine to me. Actually I was coming off a long sweeping turn as I finished fourth gear. Popped it into 5th and wound it out to 7200. I meant to let go at 7 but the sound and power was amazing.
Old 09-02-03, 07:37 PM
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145 on track, pacific body kit, med whale tail, 225/50 15 on front 265/50 15 rear, sup drop 1.5 inch. 130 fine, above 130 steering soft and slow , lift no problem. steering box is the problem. at 140 experanced some tire rub in rear, springs too soft fr/rear add to steering problem, fix steering and stronger springs will be back up there agin no problem
Old 09-02-03, 08:01 PM
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My buds FB with ?00HP, with a documented 178MPH run had a bone stock body and no wing. It felt like it was wandering left and right in the back end but only when the car reached top cruising speed.
BTW it was geared.
Old 09-02-03, 08:07 PM
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with how much HP?
Old 09-02-03, 08:19 PM
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yeah the main problem is our cars dagger shape. It CAN become unstable at high speeds, which can be counteracted with things such as a spoiler, air dam, wide body etc. Anything that is designed to create additional downforce will help.
Old 09-02-03, 08:44 PM
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shape is too aero but can be made stable with ease for high speeds.
Old 09-02-03, 08:50 PM
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I had my FB to 167MPH once. Right front fender peeled away, the sunroof popped out, antenna mast bent and I was outrunning my headlight beams...

That's a lie.

I did used to run country roads in Kansas with the pedal floored for several miles - the speedo was buried. The only thing I used to notice was front end lift that was somewhat disconcerning... Also, wind buffeting would sometimes cause a significant bowel movement...


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