Do engines have rev limiters?
Yes, pretty much every car has a rev limiter, and modern ones are always controlled by the ECU. Rev limiters are usually done one of two ways – by cutting the amount of fuel injected (fuel cut) or by not firing the spark plugs (spark cut).
What are factors limit the Max RPMs on an engine?
The pistons and rods move up and down very fast at high rpms and not only do they move fast, but they have to CHANGE directions very fast and because of their momentum, it limits the rpm at which the engine can max out. Also, the valves are moving up and down very rapidly, the spring retainer is moving up and down (don’t want that to pop loose).
What should I do to increase the RPM of my car?
If you increase boost pressure AND the RPM limit, your car will break in a spectacular fashion. Or if you REALLY want to rev to 8500 safely, buy a Mazda RX8. Allowing the engine to aspirate better; increasing its volumetric efficiency, increases it’s rpm.
Can a rev limiter be removed in a custom DME?
The rev limiter would have to be removed. This would be involved in a custom DME. With the limiter removed then you’d be able to blow it up if you wanted to. To support the higher revs, the vehicle would need the engine internals worked on. Stronger camshaft (s), valves, valve springs. (Head work).
What happens when the engine RPM hits 7800?
There is also a phenomenon known as “valve flutter” which happens when engine rpm hits a perportion of the natural frequency of the material the valve is made out of. Basicly, it makes the whole valve shake and bounce, sometimes high enough to hit the piston. IIRC this is between 7800 and 8200 RPM for most steel valves.
Can a rev limiter keep engine RPM below the redline?
In the case of “neutral” or shifting up too late, a rev limiter can easily keep engine RPM below the redline. If a manual transmission is shifted down too early, the speed of the vehicle will drive the engine over the redline. In this case, a rev limiter will cut engine power but it cannot prevent the engine’s RPM from going beyond the redline.
What causes the rev limiter to bounce off the throttle?
These types of limiters activate at the set RPM and “bounce” off of it if throttle is applied. The “bouncing” occurs because the limiter will cut off fuel or spark at the set RPM, which causes the RPM to drop. If the engine is in a state of open throttle when the RPM drops, the RPM will then raise back to the limit.
When is the second stage of the rev limiter activated?
The second stage is activated after launch to set a higher RPM limit for wide-open-throttle acceleration. There is considerable variation between manufactures on where to have the redline for their engines: from 100 to 12,000 RPM.
Do you need a rev limiter on an automatic transmission?
In the case of an automatic transmission in “drive” mode, the engine RPM stays safely within the range that the transmission chooses. Only when over revving the engine in “park”, “neutral” or “manual” modes is there any need for a rev limiter. These vehicles often do not include a tachometer.