The Oldsmobile Connection

[sean000]

Anyone know what max rpm (red line) is on my 83 Cutlass 3.8L V6?

[GraveReaper0]

You can find out by puting the pedal to the metal. :D

[Erroneous Restrictionism!]

Redline is at 5300rpm

[sean000]

Thanks, where did you find that?

[88 Coupe]

GraveReaper0 wrote: You can find out by puting the pedal to the metal.
Actually, that would not help him find his answer.

Norm

[88 Coupe]

sean000 wrote: where did you find that?
I would like to know that, also.

Norm

[Erroneous Restrictionism!]

sean000 wrote: Thanks, where did you find that?

I have pic of a 3.8 with a tach, looked at a pic of the tach.

[88 Coupe]

Erroneous Restrictionism! wrote: I have pic of a 3.8 with a tach, looked at a pic of the tach.
Is it the same 3.8 that sean000 has?

[Erroneous Restrictionism!]

Between 1983-1987 the 3.8 when through very little changes. So....yes that would apply for his 3.8...Just like it applies for a 1995 3.8.

[TheLSS]

Actually, 5300 RPM is the shift point for the transmissions when you hit WOT. And to add to that the stock tachometers on cars are nowhere near accurate. Where the governor kicks in I would think that is what sean000 is getting at. I would imagine the governor kicks in somewhere a little north of 5300 RPM, say, 5500 RPM, but I don't know for sure, I've never hit the governor in a car powered by the 3800 because of the obvious constraints of using a automatic transmission.

[Erroneous Restrictionism!]

TheLSS wrote: And to add to that the stock tachometers on cars are nowhere near accurate.

Just curious!...which cars and their years?
It's hard to imagine that car manufactures couldn't figure out a simple.."timing sequence"!

[andrewk]

Erroneous Restrictionism! wrote: TheLSS wrote: And to add to that the stock tachometers on cars are nowhere near accurate.

Just curious!...which cars and their years?
It's hard to imagine that car manufactures couldn't figure out a simple.."timing sequence"!

Dont know about years or specifics, but I would bet they are "near accurate" if accurate were plus or minus 300 rpm or so. Typically the error percentage is somewhere in the 2-4 percent range, but that with cable driven tachs, not electric ones.

The electric ones that I have used on my Oldsmobiles were very accurate, since there was no gear drive in the tach to cause an inaccuracy. It's my understanding that excessive backlash in the gear head unit can cause great inaccuracy. Can anyone attest to that?

For what its worth, I replaced the one on my motorcycle, which is cable driven, and noticed a difference in what the gauge read at crusing speed. It was about 4 percent lower than it was before, but i never took the old tach apart to see if it had excessive gear wear.

The HEI tach port should be extremely accurate, since it is very simple math to figure out crank speed from a cam driven accessory. I am not sure what in the circutry could cause inaccuracy, maybe someone with a little more experience will chime in.

[85cieraholiday]

Erroneous Restrictionism! wrote: Between 1983-1987 the 3.8 when through very little changes. So....yes that would apply for his 3.8...Just like it applies for a 1995 3.8.

There was one big change, the addition of fuel injection. Power jumped from as low as 110hp in 1983 to 160hp in 1988.

In 1986 roller valve lifters were added, In 1988 the 3800 series was introduced "The new 3.8-liter 3800 V-6 had a redesigned cylinder block with balanced shaft chain driven by the crankshaft."

3800 tach pic

Here the 3.8 has a higher redline (though not much higher) then yours.

Would the fact that the 83 is rear wheel drive have any effect here?

[TheLSS]

Erroneous Restrictionism! wrote: TheLSS wrote: And to add to that the stock tachometers on cars are nowhere near accurate.

Just curious!...which cars and their years?
It's hard to imagine that car manufactures couldn't figure out a simple.."timing sequence"!

I meant this in reference to a real tachomoter that is used to measure chrankshaft RPM for diagnosis. Your tachometer could be reading 2000 RPM when in fact it is at 2300-2500 RPM. It's good for a basic guideline, but it does nothing when you need the correct information. If you actually use a good Scantool and use the live engine monitoring system, you will see that an enging actually fluctuates about 50-100 RPM while running. Do we see that on our vague tachometers on the dash? Nope. That was where I was coming from. And this is common along all car manufacurers(unless the tach is an accurate digital display) and models. And did you know that spedometers have about a 15% error range. That means that when you seem to have your speed at 80 km/h, you could be going 90 km/h. Manufacturers put the speedos so they read ahead that 15% to keep people from speeding and not even knowing it. Contrary to popular beleif, the guages on your dash are not as accurate as you may think they are.

Erroneous Restrictionism! wrote: Between 1983-1987 the 3.8 when through very little changes. So....yes that would apply for his 3.8...Just like it applies for a 1995 3.8.

By the way, the L36 3.8 shifts at WOT at aprrox 5500 RPM, and this is in a 1995 Oldsmobile 88 LSS. So there were changes. I'm know these cars could take 6000 RPM without a sweat, but I have no idea where the governor actually kicks in. I do know that the L67 engines(supercharged 3.8) shift when the tach hits 6000 RPM, and they are under more stress than the naturally aspirated L36 engine.

[Erroneous Restrictionism!]

TheLSS wrote:
Contrary to popular beleif, the guages on your dash are not as accurate as you may think they are.

Who's belief?....Auto techs?....auto makers?....aftermarket companies?...