Rev Limit

[dumbo]

So why did Toyota lower the rev limit on the post 89's? I know the crank was changed but curious as to why the rev limit was lowered.

Second question. Is there anyway to raise the rev limit while using the Maft Pro? Something small I can wire in?

 

[supraguru05]

the crank became heavier so i would suspect that the increased inertia loads caused the reduction

 

[Poodles]

MAFT Pro is a piggyback, as such it's not going to be able to raise rev limit.

 

[hvyman]

the crank became heavier so i would suspect that the increased inertia loads caused the reduction

90-92 it was drop 250 rpm. i have a 89 with a late block late crank.

 

[dumbo]

MAFT Pro is a piggyback, as such it's not going to be able to raise rev limit.

I know, I mean is there anything one can wire in. Similar to the HKS speed defender.(If thats the right name?)Or is a standalone the only option for higher revs?

90-92 it was drop 250 rpm. i have a 89 with a late block late crank.

So does your engine/tach only rev to 6250RPM?


I'm going to be a running a 7M crank/late model block with pre 89 electronics, so the rev limit is going to be 6500RPM, can't see it hurting anything. Want to rev it higher if possible before I upgrade the ECU.

 

[nick88]

Why will you be using the 7m crank?

In my opinion the 6m is better, it is lighter, can be balanced by a machine shop, and has a higher rev limit, but they both have their pros and cons.

 

[hvyman]

^ the crank doesnt determine the the redline its the ecu.

dumbo - 86.5-89 redline is 6500. my 89 is 6500.

 

[nick88]

^ the crank doesnt determine the the redline its the ecu.

dumbo - 86.5-89 redline is 6500. my 89 is 6500.

But the redline was determined by the crank.

 

[jdub]

^ the crank doesnt determine the the redline its the ecu.

dumbo - 86.5-89 redline is 6500. my 89 is 6500.

The crank does determine absolute RPM limit (among other things)...a safety margin is built in to prevent exceeding it. The ECU enforces the limit

 

[hvyman]

good to know. but what about the people that are revving past stock rev limiit? and is that why they dropped the rpm after 89 and the 7m crank?

 

[dumbo]

Ahhhhh!!!!...LOL

Who's reving past the 6250/6500RPM limits, how, and what internals are you running. Is it possible to do it with a piggyback?

Also what spins up/higher better, 6m/7m crank?

Basically I wanna rev my engine over stock. With the maft pro, there must be a way to trick the ecu.

 

[grimreaper]

89 with 6m crank (or at least 6500 rev limit) with the newer reinforced block. i can hit 7000 as i shift 1-2 or 2-3. Lightweight flywheel makes it easy to over spin.

 

[Poodles]

No, the 7M crank is better, or they wouldn't have changed them.

 

[dumbo]

No, the 7M crank is better, or they wouldn't have changed them.

My thoughts as well, but I have no proof. Curious why they lowered the rev limit though.

 

[Poodles]

My guess would be the higher chance of over-rev because of the mass or some harmonic. The engine doesn't make all that much power at that level anyway.

 

[nick88]

I think it had something to do with the weight of it.

There is pros and cons to each crank, IMO the 6m is better and revs higher but the 7m is smoother.

 

[TurboStreetCar]

I would imagine that there is more too it then crankshaft for rev limit. Things like valve train and connecting rods are pretty big factors too.

If the valve springs can't take the rpm the valves will float.

If the rods can't take the rpm they'll put holes in the block.

 

[dumbo]

I would imagine that there is more too it then crankshaft for rev limit. Things like valve train and connecting rods are pretty big factors too.

If the valve springs can't take the rpm the valves will float.

If the rods can't take the rpm they'll put holes in the block.

No doubt, but the only difference between the two engines was the 6m/7m crank(and "beefier" block), no argument there. So how are people "over reving" there setup, and how are they doing it. Is a standalone the only way?

The 7m crank is heavier and can't be revved as high, sounds like b*** shit to me. Toyota changed for a reason they must haved.

 

[nick88]

I would imagine that there is more too it then crankshaft for rev limit. Things like valve train and connecting rods are pretty big factors too.

If the valve springs can't take the rpm the valves will float.

If the rods can't take the rpm they'll put holes in the block.

The rods, valves, springs, cams, pistons are the same.

No doubt, but the only difference between the two engines was the 6m/7m crank(and "beefier" block), no argument there. So how are people "over reving" there setup, and how are they doing it. Is a standalone the only way?

The 7m crank is heavier and can't be revved as high, sounds like b*** shit to me. Toyota changed for a reason they must haved.

A 6m weighs 45 and a 7m weighs about 65. It is the only difference between the motors with different redlines. So if nothing else changes, how can you call bullshit.

 

[TurboStreetCar]

The rods, valves, springs, cams, pistons are the same.

I'm refering to setting a rev limiter on a built motor with a standalone. Those are things to take into account when raising it from stock.

No doubt, but the only difference between the two engines was the 6m/7m crank(and "beefier" block), no argument there. So how are people "over reving" there setup, and how are they doing it. Is a standalone the only way?

Only way is with a standalone or iirc rebic lc.