maximum speed/ govenor?

Racincc85 · 01-11-2005, 11:34 AM

I've got a 1990 lesabre with about 150k on it. It runs really well and has been properly maintained. The engine pulls strongly to redline in first and second gear. It hadn't been on the highway in about 3 months, so last night i took it out for a good hard run on the highway to clean all of the deposits and junk out of the motor. There was hardly any traffic, so i decided to see how far i could push the car, just for kicks. The speedometer only goes up to 85mph, but i got the needle past that and hit the stop which was probably right around 100. Fortunatly i put a tach on the car, so i knew i was still accelerating once i hit the stop in the speedometer. The car kept accelerating till i hit 4200 rpm, and stopped. At this point i had no idea how fast i was going. I can't believe the strong 3.8 gave out at 4200 rpm in 3rd gear, as thought it was capable of much more. I'm hoping that the car just has a speed limiter, because that is pretty pathetic if a motor like the 3.8 can't pull to redline in 3rd gear. I know this car is not a race car and i do not drive it like such, i just like to know the limits of whatever car i am driving. Does anyone know if this car has a speed limiter, and if so what speed it engages at? What speeds have others been able to achieve in their lesabers of around the same year?

redly1 · 01-11-2005, 01:44 PM

Did the car completely cut out, or did it just plateau?

]Way back when I was in high school, my mom had a 90 Buick Century with the 3.3L (I've heard it's essentially a 3800 with a shorter stroke). I took it out for a drive one day and had it hitting the top speed cutout (speedo only went to 85 in that car, but I think 109MPH is a common limit).

Anyway, I hit the limit a few times and then boom, ratttle rattle. The car sounded like a damn combine. Turns out one of the pistions shattered!! Good thing the car only had 28K miles....free motor!!

Racincc85 · 01-11-2005, 08:37 PM

it didnt cut out, it felt like more of a plateau. The engine was running smooth at 4200 rpm ( i didnt let it shift into overdrive, i kept my foot planted to the floor the entire time) and just sat there until i let off about 10 seconds later when i noticed the water temperature had gone up about 25 degrees. If i had to take an educated guess, i would say i was probably going around 105-110. I can't believe that a car that's putting out 170hp and 210 lb-ft tops out at that slow of speeds. I've pushed my friend's nissan altima with a 150hp 4 cylinder in excess of 120 mph. Is it poor gearing that is causing this, or is it just a govenor that is extremely smooth which allows the car to cruise at 110?

I was actually hoping that my car would shatter a piston or throw a rod too lol. It'd give me an excuse to get a new car sooner, and what fun is it sending a car to the junkyard in working condition? I'd rather have some fun and see it go in an exciting way, like rigging an ejector seat and bailing out at 110 and seeing what happens!

redly1 · 01-12-2005, 12:28 AM

Ahh...I think I've encountered the same thing in a 88 Bonneville I used to have. Any governor I've encountered in a car (and I've explored alot of them...Honda Odysey 3.5L, Olds Cutlass 3.1L and 3.4L, Olds Intrigue 3.5L, Buick Century 3.3L, Olds Silhouette 3.4L, Toyota Camry 2.2L, probably more)....the 88 Bonneville and an 85 Olds Cutlass 442 were the only ones that I ever topped out and just hit a plateau...no abrupt cutout.

I'm to scared to try anything over 75mph in my 90 Lesabre, as the only thing that is holding it together is rust.

Anyway, I really don't have an answer to your concern. If your really eager, you might try installing a 120+ mph speedo to see where you really are at top speed. Have fun!!

auto trainy · 01-12-2005, 04:44 AM

Its possible,because my 98 olds will not go over 3800 rpms in neutral or park and when I asked a friend at GM he told me its a over rev set point in the computer so not to blow the engine,so yes maybey they have something to stop you from overworking the engine at high end in third!

Flatrater · 01-12-2005, 05:36 AM

You reach fuel cutoff at 4200 rpm. The car is designed to do that.

Racincc85 · 01-12-2005, 10:24 AM

It's surprising that a fuel cutoff could be that smooth and let the engine run right at 4200 rpm. There was no cutout or drop in engine speed. Are you sure a car this old would a have a governor? I'm beginning to think that its aerodynamic drag that's limiting my speed.

buickmastermind · 01-12-2005, 12:09 PM

No, fuel cutoff results in a speed drop, as noticed when you floor a 8.1L Yukon, and it tops out at 100. It hits it, falls to 95, and immediatly climbs back up, hits 100, and falls again to 95. Does that every time. As for the cars, I belive its still in the governor of the tranny. There is a check-ball that will cut-off the 4th gear shift signal fluid path when the car reaches a certain speed (controlled by the rotation of the governor). The path is cut off, the tranny won't shift. Some newer ones will also send a signal to the computer to hold the motor from dangerous long periods of time in the redline. Remove this checkball, and at about 4400 rpm, the tranny will shift to 4th, and you will have a whole new range on your speedo to play with.

redly1 · 01-12-2005, 01:24 PM

excellent response, buickmastermind

Racincc85 · 01-12-2005, 07:12 PM

very excellent reply buickmastermind; i never new such a govenor system existed. Do you think that the 90 lesabre would have the limit that prevents the motor from being held near the redline for long periods of time? I find it hard to believe that the computer could limit the engine speed so smoothly, unless it is dropping ignition to certain cylinders (like a MSD rev limiter does) instead of fuel. I would think that the 3.8 would just pull to redline in 3rd gear but not upshit to 4th due to the check ball. This thing is gonna annoy the hell outta me until i find out whats really going on.

crarchu · 01-13-2005, 02:17 AM

i have a friend who owns a 99 grand am speed limiter set at 105 it cuts back then back up ,used have a 90' buick regal though with digITAL speedo hit 120 AND STILL HAD MORE 3800 MOTOR.

redly1 · 01-14-2005, 01:31 AM

mph or kmph??

buickmastermind · 01-14-2005, 12:44 PM

Since you have the 3800, the computer should hold the motor off the redline. The older style motor(86-87) didn't have that "feature" installed, nor did it have a pin to limit how far the speedometer could wind up. Unfortunately, I am not entirely sure how the computer can smoothly limit the speed. My guess is that there is a kind of secondary throttle, or valve, that will close to prevent the amount of air needed to hit the higher RPM from getting in, which would give the plateau effect. They do make racing chips for the computer, however, that won't have the limiting "feature". I have no idea how much they cost, though.

crarchu · 01-16-2005, 02:16 AM

mph,but it was cool pushing the kph button though

chevelleman · 01-17-2005, 11:43 PM

i have a 89 olds eighty eight which has the same vin C motor your buick has i also installed a tach for kicks because i was always curious as to where my motor is revving anyway considering i have the same motor and probably close the the same electronics it should pertain to your car as well

anywho here goes....

in my high speed endeavers i have pulled way past 4200 rpm with my car in third gear i have pulled all the way up to about 4900 rpm while having a friendly race down an empty flat stretch of rode with my buddy who has a car with a speedo that goes to 140 anyway we were seeing what kind of speeds we could get out of them and my car revving up to about 4900 rpm when the other car was beside me was showing about 125 mph i know my car does not have a governor i would bet yours does not either

i would guess that your car needs to be cleaned out some more i know when i got my car it was babied very heavily for its entire life and was a turd when i started driving it but it will eventually start clearing out and you will have more power

POST REPLY TO THIS THREAD