Redline early

[maddyfresh1]

Cant figure it out but my car redlines at 5500 instead of 6300 rpms...Any idea why?

[Bama420]

****'s ****ed up.

[kbrew8991]

do you mean redline as in thats what the gauge says - or it hits the rev limiter at 5500 instead of 6250 (stock)

[maddyfresh1]

yeah it hits 5500 instead of 6250...

[328FTW]

Gauge might be bad are you looking at the standard dash guage or an aftermarket one?

[maddyfresh1]

standard....

[datguydeni]

shouldn't be going to readline anyway on a 5sfe o.0 loses breath starting from 5000-5200

[maddyfresh1]

yeah i know...but still would like to know what is keeping it from reaching that point....

[PseudoKirby]

Originally Posted by datguydeni

shouldn't be going to readline anyway on a 5sfe o.0 loses breath starting from 5000-5200

E-ram electric supercharger?

are those those scam ass things off of ebay?

I cant believe someone wasted $50 on a dyno for that..

[datguydeni]

the dyno graph probably done years ago. but that's what it is lol

[mrturrari]

Does it fuel cut or is it just struggling to get there? When you hit fuel cut it will start to pulse on and off so you can't rev any higher. That can also seem to be happening when you have a clogged fuel filter or pump that is not flowing like it should.

If it is just having a hard time getting there then check your timing, check your ignition components (do a tune up) then check your cam timing. Also could be a clogged cat keeping it from flowing up there.

A stock NA MR2 has it's best accelleration if you take it to 6300rpms in 1st gear.

[kbrew8991]

you want to shift into the same horsepower you shifted out of... I've had best results with mine around 5500-5700 depending on gear

[maddyfresh1]

well it doesnt struggle getting there at all. It acts as if i hit the red limiter. My car was sitting for 5 years just got brakes and clutch on it. And when i started running it i put a bottle of fuel injector cleaner in the tank. I have some new spark plugs wires im going 2 put on... Right before i stopped driven my car i put some spark plugs in but i wasnt having that problem.

[mrturrari]

Originally Posted by maddyfresh1

well it doesnt struggle getting there at all. It acts as if i hit the red limiter. My car was sitting for 5 years just got brakes and clutch on it. And when i started running it i put a bottle of fuel injector cleaner in the tank. I have some new spark plugs wires im going 2 put on... Right before i stopped driven my car i put some spark plugs in but i wasnt having that problem.

Sounds like it is ignition related. Put the wires on and get a cap and rotor as well. Check the plug gap too and make sure it is 0.043". You should test your coil as per the BGB as well because if it is getting bad the spark could be getting weaker in the upper RPMs.

[mrturrari]

Originally Posted by kbrew8991

you want to shift into the same horsepower you shifted out of... I've had best results with mine around 5500-5700 depending on gear

Using horsepower will only get you in the ballpark and is usually low. Horsepower is a measurement of work done over time and since we have no way to know how much time you spend at each RPM in each gear it will make it impossible to calculate the best shift points.

Now torque on the other hand is a measurement of thrust and doesn't have a time component to figure out. You want the maximum thrust at the wheels that you can get any given time. To figure that out you just need to take the ratio of gears multiplied by the torque at the RPM you are shifting from and to. You don't have to get it to the wheels just to the final drive because you just want to know comparitavely which will give you more torque.

Example 1 shifting at 5700
A 5sfe at 5700rpms has 95ft/lbs at the wheels in 3rd:

95 / 1.322 x 3.285 x 4.176 = 986ft/lbs at the wheels

1st gear 3.285:1 to 2nd gear 1.96:1 drops to 3400rpms:

5700 / 3.285 x 1.96 = 3400rpms

A 5sfe at 3400rpms has 115ft/lbs at the wheels in 3rd:
115 / 1.322 x 1.96 x 4.176 = 712ft/lbs at the wheels

Example 2 shifting at 6300
A 5sfe at 6300rpms has 77ft/lbs:

77 / 1.322 x 3.285 x 4.176 = 799ft/lbs at the wheels

1st gear 3.285:1 to 2nd gear 1.96:1 drops to 3759rpms:

6300 / 3.285 x 1.96 = 3759rpms

A 5sfe at 3759rpms has 122ft/lbs:
122 / 1.322 x 1.96 x 4.176 = 755ft/lbs at the wheels

So if you shift from 1st to 2nd at 5700rpms you will be going from 986ft/lbs at the wheels down to 712ft/lbs at the wheels. If you however shift at 6300rpms you will go from 799ft/lbs at the wheels, and it was higher then that for the entire time leading up to it, to 755ft/lbs at the wheels which was lower leading up to it.

If you rev match then the shift points you calculate like this will be spot on. If you pop the clutch then you want to shift a little earlier because the momentum of the engine will give you a boost that will make your shift settle in a slightly higher RPM in 2nd. You do these same calculations for each gear because as you shift the gears get closer together.