Try putting the top up

 

Alright, someone who knows math.
What formula/calculator are you using?

From 1991 FSM page TD-12:
Auto NA ratio 3.909
Auto NA conv 4.1
MT Turbo 4.1
MT NA 4.1 or (4.3LSDGTU)
Auto turbo ??? Were there any?

 

I would like to know.

Yesterday on my way home from San Jose to Sac...I hit just over 120mph on hwy 80, about a 5+mile stretch. 2pm in the afternoon, with the top down. It started to get quite choppy with the windows down....had to put them up.

 

Weight has nothing to do with top speed. It's a function of drag vs power. It may take longer to get up to speed in a heavier car, but the top speed will be the same.

 

In my 91 vert, I have hit 127mph. What is curious to me is that I shift out of 4th gear to 5th gear at ~7200rpm and ~115mph. She is completely stock, with stock wheels and stock size tires. Can someone use the formula to determine what speed I am really going according to RPMs? I also believe that I have a 4.1 rear-end, just guessing by where I shift compared to the picture that was posted earlier by 2887s (7200rpm and 130+mph).

 

is that another guess?(on the acid).

you're right on the money, concerning the car tho.

 

The Factory servce manual doesn't include the NA 'vert rear end gearing which is 3.909 on the 88 and 91, as well as possibly the 89 and 90 (I haven't been able to confirm the 89-90 yet in more than one place or car)

Well the 3.9 rear end in 4th gear gets 17.8 MPH per 1000 RPM. So its pretty easy to figure out his actual speed based on that.

*edit
BTW the 3.9 rear end in 5th gear (thats .71 on a vert) gets 25.1 MPH per 1000 RPM.
End edit*

But then I believe he is using the 225/50/15 on the stock rims (since that was what his picture had and he said that he had 50 series tires on). But the 225/50/15 is only 23.9" in diameter, thats about 3.3 percent smaller than the stock 205/60/15 (24.7" dia), so his speedo is off aprox 3.3%. Simply subtract that number (around 4.3 MPH) from the speed calculated from the RPM and you have his true speed.

Which would be pretty close to 124 (+ or - 1%) which is exactly what Car and Driver found to be the top speed on a '88 manual tranny 'vert back in January 1988.

 

unless you had your speedo recalibrated for the lower profile tires. My opinion, if you haven't, you should.

Icemark.... I didn't know you had finished your T2 Vert conversion. Did you do a S4, S5, are go for a S5 into a S4?

 

Yep I sorta finished it (my 88 'vert), I still have to do the cat back exhaust and I now need to locate a single Ronal R9 wheel (running the stock rims back on right now, I cracked a wheel, just this week or it was already cracked and I never noticed it and the girl that sold me the wheels lied).

I ended up going with the Greddy 2 row FMIC (I got a local guy to get it for me for $800+ tax) but other than that it is a S4 with S5 rotors. I am still using the 88 vert NA air flow meter as well, but I will eventially replace it when I find one at a reasonable price.

The '88 model 338 'vert ECU works fine for running the motor, but I did use a pressure sensor off a 88 T2.

I drove down 5 to San Diego and back last weekend. Its the first long trip since the rebuild and following 1000 mile break in on the Jspec. It performed flawlessly. It was pretty cool on the way back up to keep up with a Audi TT and a TRW I Force Tundra at 120 + miles an hour (of course the Audi and I blew the truck away getting in and out of traffic).

The only complaint I had was that the wipers don't work real well above 100. I don't remember having that problem on my old Sport.

I got laid off back in febuary, so I have had a lot of time

 

wow, finally I have something to feel good about, the last time I was on the highway (ironically, going to my monthly drill with the Army Reserves, I am an MP) I hit about 120 in 4th without trying, could have gone more, before shifting. 90' GTU, she isn't the fastest, but at least I can beat some ragtops in the top end =)

 

Last night I had the top up for some reason and was able to get up to "120" on flat ground (headlights up). Still accelerating slowly at this point, too. Tach read 6800 or 6900, 3rd gear Automatic. So I feel a little better. The really good news is how stable the car is in this situation.