Hey, wow, it's been a while since I've been on here!
Looking forward to seeing some of the new progress on some of the cars and such!!

Anyways, I am just wondering a few things for you guys who have a very low sense of self preservation (like me) and enjoy making top speed runs.

Mine tops out at about 220km's in 4th gear, that's at about 8500 rpms. Thats 136 Miles/hr.
I havn't had a chance to try in 5th, since there aren't really too many open stretches around here, but I hope I could get more speed than that.
Ok, I know my car is WAYYY faster than a stock 7, and I am running legit high 14's in the 1/4. How in the HELL can the top speed of a stock 7 be spec'd at 132?????
The gearing doesn't make sense to me either, since I'm 500 rpm's past the stock redline to get that speed, I know a stock 7 doesn't make anywhere near than much power past redline.

Are the factory posted speeds attained in 5th gear????
Doesn't make sense to me. I'm surprised.
Oh ya, these are N/A speeds only.

Anyone else had any experience with this? What's have others topped out at?
L8r
Dan

 

I have a 90 GXL and I have hit 140 in 4th gear ~9000 rpm

 

why not run her up in fifth for top speed? like shift once you hit 135 and get back down into your powerband....

I'm still breaking in my rebuild so I've been nice to mine lately. Got it up to 128 in a one mile stretch in 5th and was well under the powerband. (shifted out of 4th at 110)

My car does 80 at 3000rpms in 5th, so theoretically 160 should be attainable. (should be at peak torque somewhere around there anyways)

 

140 mph in fifth in a series 4 N/A with mods (no header tho). I dunno what my top speed is now that its turbo'd though. And I probably never will. 140 is fast enough for me.

 

i got 155 in 5th and i was at like 7000rpms, I could've gotten more, but i was racing a dsm and he was so far behidn ( he wantred to run me rolling) that i decided to slow down to be able to laugh in his face.

 

lol... holy ****...
nice job....



155...



......



.....


.....still in shock....


...

...

..

.

 

Honestly its been a long long time since I don't take her up to high speeds. I do remember taking her up to 135MPH, (I just discover a couple of months ago that the speedmeter is off by 5 MPH, so it was most probably 130 MPH) in fifith gear. I had to let off, it actually felt dangerous the last time I did a high speed run!

One thing that I do remember, after shifting @ redline from 4th gear, the car would fall on its face once it hit 5th gear. I mean it doesn't pull as hard as the other gears did..............

 

You guys aren't going by the stock speedometer, are you?

 

I have a stock speedometer and I hit 140 even in 4th gear at 8000rpms or pretty close. When I was stock with just a high flow cat and bonez filter I run 135 basically stock. The engine has a fresh rebuid and was running perfect compression at the time. Now im modded to hell (almost) and going to make another run after I get headers and some dyno time.

Bambam7. Look at mazdaspeed7s old sig. He took a pic of his car running what looked like 148 mph. Anyone who does 155 in a street N/A probly has a bad odometer.

Bambam. Thier has been a few N/As being wildly modified since youve been gone. Thnx to you PPnos , mazdaspeed7 , pday slvrotor and some others who have motivated others...Heres my mods that I have done but not nearly finished.

Fully ported manifolds to engine.
Pineapple sleeves cut shaved and J/B welded in
Custom short intake with heat shielding and forced air
Bonez race pipe and single cat back (iching for headers)
TB mod with rerouted coolant line exc. Soon to be ported
S-AFC
200lb weight reduction
25k on stock rebuild, wires , Nitto drags, Enkie RSE rims
Custom full interior
Bonez clutch
lowering springs

Future and WTB light flywheel? Short shifter? Dual gauge pod with gauges , more nittos? Ummm darn forgot the rest but I want them bad. Oh and some headers before next week? anyone?

 

You all need to get a GPS in your cars for those runs to confirm the speed.

Bambam, do you still have that DIY Wideband?

James

 

I use GPS for my speed runs... had her up to 130 @5k in 5th tonight but was running really lean, so I backed down.

I also noticed a major loss in power once I hit fifth. maybe it would be better if the ECU wasn't aware of the gear we're in? Anyone unplug their gear sensor switch from the tranny?

 

See, that's what I'm talking about.
I don't understand this discrepancy. Unless the speedos or WAYYY off, I know mine is very close, There is a mobile cop radar trailer that they place around town, that flashes your exact speed, and mine reads about 2-3 km fast at 100 km/hr. How can some cars be going 140 at 8K, while my car does 136 at 8500 rpms?
Must be the speedo, who knows. I need a GPS.
And yes, the OZ wideband rules!!!!
I will take a road trip soon, and find a nice stretch to get a 5th gear run. I want to see 150!

 

I think that 150MPH in a N/A is nearly unatailable without different gearing, or a mod list that is as long as my...........well it would have to be long. Increasing the top speed of a car isnt as easy as youd think. Look at modded FDs. There stock top speed is what, about 163?? Now with about 100HP more than that, they can hit about 170, maybe slightly over. So on a N/A whrere mods dont give you nearly as much power , there is no way to increase our top speed that much without crazy modifications. Plus the stock speedo is way off at higher speeds. That thing probably isnt accurate past 70MPH. If it says your going 140, I bet your going closer to 130, maybe even slightly slower.

 

I think the speedo error has to be vehicle specific. I used my GPS to calibrate my speedo (in my head vs what the guage says) and its not off by much. 2-3mph at the most.

 

2-3 mph at what speed? Yes its probably pretty accurate up to maybe 70MPH, but after that it gets further off the faster you go.

 

Rx7.com sells a final gear which they post on their websight is capable of reaching 191@5th its the 3.90 final drive. I dont quite understand this i mean how the hell would an FC reach that kind of speed ?? I mean that would be with crazy mods right??

 

2-3 mph error up to 120... that was done with my ex gf though and she wasn't the most accurate instrument either so I'm gonna do it again today. 100 miles to go on my rebuid before she's ready for some mustang mashing. (and when I get more fuel)

Taller rear end gears will make the top speed potential higher because the rear end will be turning faster in relation to the engine compared to the same engine rpms and shorter gearing. (bigger #) What that also means is that it'll take more power to turn the diff (due to less mechanical advantage) and your top end might not be significantly increased.


NOTE: Because I'm running a bone stock fuel system on a heavily street ported engine at the moment, my results are very skewed due to fuel cut at higher rpms. I had the same problem just running open exhaust (header and 2.5" all the way out the back) and a cone intake with ported elbow and TB mod. The new motor is even thirstier!

 

The 3.90 gearing is rated to be ABLE to hit 191 mph given the right circumstances, that doesn't mean that your car will be able to do 191. You'd have to have the right amount of power, weight, and more importantly Cd to be able to actually hit 191. That's just saying the gearing is tall enough to hit that speed.

 

In an 86 N/A?
Care to explain how you've eeked an extra 88 horsepower out of the engine?
And why you weren't going 176 mph at 7000 rpm in 5th like you should have been?
I smell bs.

Unless, of course, you have incorrectly sized tires.

 

I hit 125 just yeasterday on my way home from seven stock. Keep in mind that is with a curb wieght of about 3500 lbs+

Car =3003lbs
Me & my brother= 350
subs+ box= 50
Extra battery, Weeks worth of close and supplies, ect.= alot!

It pulls very hard with out all that wieght past 125. In the cold weather of the north west the car pulls up steep grades at 110 in 5th gear.

Also I already know the crazy gearing of a 3.90 final drive. All verts have this gearing.

One last thing. A wisely moded N/A can pull really hard. Especially in cold weather with NO CAT! The cat takes so much power.

 

I just dont see these types of speeds happening on a N/A. Not trying to call you people liars or anything, but Id have to see it to believe it. I have a decently modded N/A (begining to wonder why I bother) and I dont think there is any chance in hell my car would do 150MPH. Yes my car is rather quick, enough to beat most N/A 4cyl cars, but in no way is it fast. 13bpower, my car is more modded than yours, and is not nearly as heavy, and dont have that 3.90 rear end, and Im pretty sure my car wouldnt pull up a steep grade in 5th....

 

Nobody here claimed to hit 155 mph in an n/a. He only said he hit 155 didn't say it wasn't a turbo.

Speedometer can be thrown off for several reasons. Tire size being an easy one. Every tire manufacturer has a slighty different way of doing things. My friend has 225 wide tires on the front of his 2nd gen but I couldn't fit 225s on mine. We didn't have the same type of tire though. There can be small height discrepancies as well.

The fastest I ever had my n/a was 136 on the speedometer and that was right near 8000 rpm in 4th gear. When I shifted into 5th the car slowed down.

Just because you have a 2nd gen doesn't mean you have the same gear ratios as a different year 2nd gen. Rear end ratio was 4.10 for standard n/a's and turbos, 3.90 for autos, and 4.30 for the obscure GTUs. 5th gear ratios also varied between year models.

Don't rule out aerodynamics. What have you done to the cars exterior i.e. wing, ground effects, front lip spoiler? The less drag the faster you can go. How much did the car weigh?

The stock n/a was rated from the factory at 127 mph.

 

anyone who goes over 110 or so is asking for trouble. The car gets very light in the front end after about 110. If you want to go fast, get something else to do it in.

 

Ive hit about 142 in my NA 240. Im pretty sure my FC can top that. I'll give it a try within a week of getting new tires and let you guys know.

 

well the name of the post is "Top N/A speed..." and that guys profile says he has an 86 GXL so :P to you