Stock Convertible Top Speed (on flat)
#1
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Stock Convertible Top Speed (on flat)
I have a 1990 n/a convertible. Last night I had the opportunity to push it's upper speed range. The car pulled strongly in 1 and 2 (automatic), but begin to bog down in 3 around 110 MPH. REVS increased slowly if at all (this is around 5500 rpm if I remember). Of course shifting to 4 did not help the situation.
I have previously gone 120 on a downhill, but this was flat ground.
The headlights were up, the top was down, so aerodynamics could have been better, but I still expected to get 130 before hitting the wall.
I am pretty sure my 6 ports are not working (finally moved to a place with a garage, hope to fix that next week).
The car is stock. Not even an intake upgrade.
I just want o find out if this is normal, or if I might have some engine problems.
I have previously gone 120 on a downhill, but this was flat ground.
The headlights were up, the top was down, so aerodynamics could have been better, but I still expected to get 130 before hitting the wall.
I am pretty sure my 6 ports are not working (finally moved to a place with a garage, hope to fix that next week).
The car is stock. Not even an intake upgrade.
I just want o find out if this is normal, or if I might have some engine problems.
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This may not be too much help because mine is a 5 speed and I had the top up, but...
a couple of weeks ago I hit @123 mph before I had to shut it down because I was coming up on traffic. That is with an '88 with slightly low compression and the headlights up.
Dan
a couple of weeks ago I hit @123 mph before I had to shut it down because I was coming up on traffic. That is with an '88 with slightly low compression and the headlights up.
Dan
#4
Former Moderator. RIP Icemark.
121 is the factory rated top speed on the 88 US 5 speed version.
I would think that the US spec 5 speed '89 might get to 125, but wouldn't think that the 90-91 (the heaviest, lowest power to weight ratio of any RX-7 and stuck again with the 3.9 rear end) would hit anything past 120 without modification.
I would think that the US spec 5 speed '89 might get to 125, but wouldn't think that the 90-91 (the heaviest, lowest power to weight ratio of any RX-7 and stuck again with the 3.9 rear end) would hit anything past 120 without modification.
Last edited by Icemark; 04-30-02 at 01:05 PM.
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Originally posted by Samps
The headlights up, will probably subtract about 4-5 mph.
The headlights up, will probably subtract about 4-5 mph.
#7
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121 is the factory rated top speed on the 88 US 5 speed version.
"121 is the factory rated top speed on the 88 US 5 speed version. "'
Really? i hit that last week at Tobay beach w/ my 88 vert, racing my friend's 328i .. it felt like the car had more to go though. i was at 4th gear at i hit 6rpm barely..
clean stock engine=cleaned it w/ toothbrush the day before=) w/ exhausts and y pipe... hmm.. we'll see.
Really? i hit that last week at Tobay beach w/ my 88 vert, racing my friend's 328i .. it felt like the car had more to go though. i was at 4th gear at i hit 6rpm barely..
clean stock engine=cleaned it w/ toothbrush the day before=) w/ exhausts and y pipe... hmm.. we'll see.
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#8
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Originally posted by go_speed_go
Is that from experience, drag coefficient computations or pure speculation?
Is that from experience, drag coefficient computations or pure speculation?
#10
Okay so I will get this out before all the BS flags go up, I got my '88 Vert up to 138. Here they come, okay I had an exhaust, bonez race pipe, magnecor wires, bonez intake, cold air box, decent clutch(don't remember which one). The car also had Tokico HP's, Tokico Springs, Racing Beat Sway Bars and Endlinks. The engine had great compression though and was in a great state of tune. Of course the top was up and lights down and the suspension being new I am sure helped keep the power to the ground. The vert has since met a tree thanks to me, I loved that car but she was crushed. Anyway just thought I would put my .02 in.
#11
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Adding horsepower will almost always increase top speed (unless it it gear limited). But top speed is like an acid trip; once you get to a certain point, it takes alot more the next time.
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Originally posted by Icemark
121 is the factory rated top speed on the 88 US 5 speed version.
121 is the factory rated top speed on the 88 US 5 speed version.
Dan
#14
Former Moderator. RIP Icemark.
You guys are mis-understanding the concept of top speed.
When the factory quotes something it is one of three things.
1. It is the top speed of the car (again in stock form) for a 3 (or 5 depending on the company) mile run on flat or banked with under 1000ft altitude (typically also a test track). Usually best of 3 or 5 runs. If you are cruising across the plains in cool dry air and have 10 or 20 miles to get up to 120, I am sure you might actually pass that factory number.
2. It’s what the factory claims is the run for insurance purposes hoping not to have the insurance companies raise the premiums so more people can afford the car. (Mazda did this one the series 5 and 6 turbo RX-7s, they actually reported lower than any mag or article reported.)
3. It’s what the factory electronically limits the car to.
Also, just because your speedo says that you are going 130 or 140 MPH doesn't mean your car really is. Japanese and American Speedos are noted to be bad at above 85 MPH (I saw one series 4 RX-7 and a RA6X series Celica that their speedos were off more than 10 MPH at 100, reporting 110 but the car actually trapping only 101 and 100 respectively).
My own speedo on my T2 converted ‘vert is off almost 3 MPH at 80 MPH, so I don't doubt that although I saw 130 on the speedo on my drive between San Diego and the Bay area yesterday, it was really only 125 or less.
When the factory quotes something it is one of three things.
1. It is the top speed of the car (again in stock form) for a 3 (or 5 depending on the company) mile run on flat or banked with under 1000ft altitude (typically also a test track). Usually best of 3 or 5 runs. If you are cruising across the plains in cool dry air and have 10 or 20 miles to get up to 120, I am sure you might actually pass that factory number.
2. It’s what the factory claims is the run for insurance purposes hoping not to have the insurance companies raise the premiums so more people can afford the car. (Mazda did this one the series 5 and 6 turbo RX-7s, they actually reported lower than any mag or article reported.)
3. It’s what the factory electronically limits the car to.
Also, just because your speedo says that you are going 130 or 140 MPH doesn't mean your car really is. Japanese and American Speedos are noted to be bad at above 85 MPH (I saw one series 4 RX-7 and a RA6X series Celica that their speedos were off more than 10 MPH at 100, reporting 110 but the car actually trapping only 101 and 100 respectively).
My own speedo on my T2 converted ‘vert is off almost 3 MPH at 80 MPH, so I don't doubt that although I saw 130 on the speedo on my drive between San Diego and the Bay area yesterday, it was really only 125 or less.
#15
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Originally posted by WestJaxVert
turbo rearend (should be the same)
turbo rearend (should be the same)
Anyway a higher gear (4.1 as found in the T2 rear ends) should let you go a little faster.
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actually, the lower the gear ratio (3.9), the higher the top speed and better mileage...and the higher the ratio(4.3), the better acceleration and worse mileage because the engine is spinning at a higher RPM at cruise than the lower ratio rear end
Grace and Peace
Matt
Grace and Peace
Matt
#17
Former Moderator. RIP Icemark.
The problem is too keep the RPMs up in a pulling range longer, so the lower rear end gearing actually hurts in this case.
If there was sufficent power to drive the car to redline in 5th, yes your statement would be correct.
If there was sufficent power to drive the car to redline in 5th, yes your statement would be correct.
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Originally posted by Icemark
No, the verts came with a lower rear gear (3.9), for better mileage in 88 and 91 (and some claim 89 and 90 as well, but I don't have proof one way or the other).
Anyway a higher gear (4.1 as found in the T2 rear ends) should let you go a little faster.
No, the verts came with a lower rear gear (3.9), for better mileage in 88 and 91 (and some claim 89 and 90 as well, but I don't have proof one way or the other).
Anyway a higher gear (4.1 as found in the T2 rear ends) should let you go a little faster.
Dan
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That is the fastest I've had my vert, and it has RB full dual exhaust, K&N intake, underdrive pulley, and maybe 100 lbs. dropped from it. 5 speed though, and I was in 4th gear at about 7300 rpm. I did this around 2:30-3:00 in the morning, and just happened to have a digital camera with me, so thought what the hell....
Last edited by 2887s; 05-01-02 at 07:04 AM.
#21
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Originally posted by 2887s
That is the fastest I've had my vert, and it has RB full dual exhaust, K&N intake, underdrive pulley, and maybe 100 lbs. dropped from it. 5 speed though, and I was in 4th gear at about 7300 rpm. I did this around 2:30-3:00 in the morning, and just happened to have a digital camera with me, so thought what the hell....
That is the fastest I've had my vert, and it has RB full dual exhaust, K&N intake, underdrive pulley, and maybe 100 lbs. dropped from it. 5 speed though, and I was in 4th gear at about 7300 rpm. I did this around 2:30-3:00 in the morning, and just happened to have a digital camera with me, so thought what the hell....
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Man, i've only gotten mine up to 110... Is there something wrong with my vert? It's really clean i've made sure of that... it's a 91 that's as fast as she'll go even in 4th.. how are yall gettin them so fast ?
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Originally posted by SoulPyr0
Man, i've only gotten mine up to 110... Is there something wrong with my vert? It's really clean i've made sure of that... it's a 91 that's as fast as she'll go even in 4th.. how are yall gettin them so fast ?
Man, i've only gotten mine up to 110... Is there something wrong with my vert? It's really clean i've made sure of that... it's a 91 that's as fast as she'll go even in 4th.. how are yall gettin them so fast ?
#25
Former Moderator. RIP Icemark.
Originally posted by 2887s
It is a vert it got the 3.909 final drive ratio, plus I'm running on a 50 series tire, not 60.
It is a vert it got the 3.909 final drive ratio, plus I'm running on a 50 series tire, not 60.
if you are using the standard 225/50 15 your actual speed was only 124 MPH