I have an 86.5 supra with the stock 5spd W58 tranny and stock 4.3 lsd. I put in a turbo motor and the tach didnt work because of a difference in resistors. So I researched and soldered in the right resistors. I got curios to see my top speed since the engine seemed to be pushing pretty hard at only 80 and according to my tach I redline(6500rpm) at 110mph. That seems extremely low to me but the car feels like its only going 110mph and being pushed to 6500rpms. Does anyone know a way to test the tach and speedometer? Or does this seem normal?

Nobody has any useful information or opinions?

hmmm i really havent looked into it but remember 4:30 brings down ur top speed soo that might be a start.

The 4.3 does have a lower top speed than the 3.9 and 3.7, but I had seen people talking about how they drove their N/A supra all the way to 150mph which would be the same gearing that I have. Heres an article on supramania.

Here is a listing of the various top speeds for the different transmissions and rear ends.

Automatic tranny, stock size tire (225/50/16):
3.73 rear @ 7000 rpm 4th gear = 199 mph
3.91 rear @ 7000 rpm 4th gear = 189 mph
4.30 rear @ 7000 rpm 4th gear = 172 mph

Automatic tranny, common upgrade size (255/45/17)
3.73 rear @ 7000 rpm 4th gear = 207 mph
3.91 rear @ 7000 rpm 4th gear = 198 mph
4.30 rear @ 7000 rpm 4th gear = 180 mph

Manual tranny (turbo), stock size tires
3.73 rear @ 7000 rpm 5th gear = 185 mph
3.91 rear @ 7000 rpm 5th gear = 176 mph
4.30 rear @ 7000 rpm 5th gear = 161 mph

Manual tranny (turbo), upgraded size tires
3.73 rear @ 7000 rpm 5th gear = 194 mph
3.91 rear @ 7000 rpm 5th gear = 185 mph
4.30 rear @ 7000 rpm 5th gear = 168 mph

Shits n Giggles calc

auto tranny with 245/65/18 (yes, these fit just fine)
3.73 rear @ 7000 rpm 4th gear = 243 mph

The only thing is that they dont list it with the N/A transmision.?? I would think that it wouldnt change my top speed by having a turbo motor instead of an N/A.

i have taken my turbo up to 145 my buddy in his n/a has been up to atleast 130 and said it creeps after that sooo i dunno. too bad nick m isnt on he would sure answer u ?..

Yea he probably would, he doesnt come on here anymore? If not that sucks, he helped me out a few times. Ill just keep researching it myself if no one else knows. Thanks alot for your input mssupra88t.

110 is for too low, you might only be going 110 but for sure you should be topping out higher then that.

my n/a tops out at 135 redline and most turbos can do close to 150 with little mods so im sure theres some sort of prob with your car

remember tho he has the n/a lsd 4:30. people hace said it would lower top speed but i dont know how much...

Im guessing that my tach has to be wrong. I found this site Top Speed Calc. and finaly figured out that with a N/A transmision and 4.3 differential the top speed should be 145.9 mph. Thanks alot for your help.

Nick M is off server our country. he left around mid to late september.

quote:

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Originally posted by MSSupra88T:
remember tho he has the n/a lsd 4:30. people hace said it would lower top speed but i dont know how much...

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n/a's top out anywhere between 140-145mph, and is redline limited. you might have wired your tach wrong which would give you false readings.

check www.4cefed.com, dr. j. has a good tach rewire diagram on there.

simply changing the motor has nothing to do with changing the gearing, so long as its still the same basic motor. (ie something that has the same rpm characteristics, and redlines about the same etc..)

gearing is all in the tranny and rearend. you're NOT topping out at 110mph, unless you have your timing advanced a few lightyears. (which i dont even think is possible), you're not topping out at 110.
-shaeff

you put it in 5th gear right?

haha.. yea Im putting it in 5th, but at first I was looking for another gear or something, lol. But I did use that website for the rewire. there are 3 things I think that might be affecting it so Ill probably just get a used turbo tach.
First of all I used 1/4 watt resistors when the origional ones were 1/2 watt. That shouldnt make a difference though
Second I bridged to resisters to add up to the correct resistance (I think a 100k and a 30k bridged to make 130)because i couldnt find 130k anywhere.
Third I used the tachometer from an automatic non-turbo so I could quickly swap it in and I had it laying around. (It has the power and O/D lights that just alway go on.)
But I did it all correct and I dont know if any of those things would really affect it. Thanks alot for the help though.

if you installed the resistors in paralell then you only have 23 ohms of resistance. that may be your problem. when resistors are in paralell the total is not added. if you knew that already then never mind. if not i hope this helps

No i didnt know that. What happens when you put 2 in a row? how does it become 23ohms?

I top out a 95MPH in 3rd gear so you must of did something wrong or you car just lost lots of power. The fastest I ever been in my car was 140 and that was on the highway so I could go too fast so I can pass other cars.

I know that something is wrong with my tach. Its not my car that doesnt have the power cause it pulls hard to 110 but i let up because the tach shows 6500 rpms. I was just wondering if wheelman had any more information, i should just buy a tach from a turbo. Thanks though

I think something is off in my dash. I get up to 100.. and i can pretty much just get straight to 140 without even knowing it. Boost stays up the whole time. and its just a matter of seconds. I hit the top i think, and my spdomter was pegged out. i was at around 5k rpm (i think, I know doing 80mph I sit at 3k rpm. and it climbs fast once i get past there. (And it drinks the hell out of gas up there too )

My car sucks gas like a V8 I think a turbo should help.