X/Flow Rev Limiter

[cskip]

The current level for the Rev. Limiter on my Ford X/flow 1600 (100BHP) is set at 5200RPM when read from the Rev. counter (VDU).

Is this too low?

How reliable are the Caterham supplied rev counters?

 

Clive.

Desperately seeking more power!

 

[Graham Sewell]

When I asked the factory a similar question about my supersrint engine, I was told that the red line is 6500 and that I should set the limiter to 7000 - must admit that I played chicken and set it to read 6500 on the rev counter when it cuts in!

 

I would think that 5200 is a little low, and anywhere between 6000 and 6500 should be OK.

 

Cheers,

 

Graham

[cskip]

Graham, Thanks for the info.

 

Anyone know if the rev. limit should be set differently between a Sprint and Supersprint engine?

 

 

[Casbar]

The rev limit for an engine, is determined by the spec, not just the cc. My 1660 xflow, is a low compression engine and provides max power at around 6400. When the engine gets re-built with forged pistons and lighted bits, the engine should safely rev to 7000+ probably 7200. You should set the rev limiter to stop you over over revving the engine, but not to stop you getting full power. You shouldn't drive to the rev limiter, so if you have it set too low, you'll never get full power.

 

A lot of rev limiters read low, so set it to the rev counter and not rely on the limiters adjustment knob. One sure way, is to get the car rolling roaded, you will then know where max power comes in.

 

I would think 5200 is too low, 6000 is probably nearer the mark.

[philwaters]

Hi Clive,

 

I have my limit set to 6500 on my 1600 x/flow sprint engine. I believe the max power (oh no, did i really just write that!) is at 6000rpm so never really need to go much above that. I used to set it at 6000rpm, but found that I would hit it when having fun, so upped so that it never gets hit anymore, but is not set beyond the limit of the engine.

 

Hope that helps.

 

Phil Waters

Q181 ABL - 1600 X/F smile.gif

[Graham Sewell]

What is wrong with hitting the limiter. Makes a wonderful sound as it cackles away to itself. I always thought that the whole point of a soft limiter was that it could used as an audible shift indicator tongue.gif

 

Cheers,

 

Graham

 

[cskip]

All,

 

Is the caterham Rev counter reliable to set from?

 

Worried about blowing the engine if I set the limiter too high.

 

Graham, Good question. I have been on the Track before and driven on the rev limiter (only for a few seconds), as there was not enough time to change up before the next corner! Hope this doesn't damage anything.

[oilyhands]

The torsional loadings on the crank will be all to hell when you hit the rev limiter since it cuts some of the power strokes, the primary and secondary out of balance forces on a 4 cylinder engine are bad enough as it is without making them worse...

 

Oily

[Gary Furst]

As Casbar stated the max rpm is a function of the componentry. My original race spec supersprint (with forged pistons, Iron crankshaft, Duplex timing chain and twin valve springs) was regularly revved to 7500rpm without problems. With the later cam upgrade it was used regularly to 8000rpm. Now with a steel crank and gear driven cam I use 8500rpm. I have even hit 9000rpm once which because of the rev limiter cutting in caused one of the valve springs to break, the bottom end was however ok.

[Graham Sewell]

Why would hitting the rev limiter cause a valve spring to break? The valves are controlled by the rockers which are pushed by the push rods which follow the cam that is driven by the chain that feeds off the crank. They don't know about the loss of sparks....

 

If you had said the crank snapped (under sudden changes in torsion) or the chain snapped I could just about follow the logic. But a valve spring? Unless the spring would have snapped at 9000rpm anyway, I cannot see how a change in speed would affect it.

 

Anyone care to enlighten me?

 

Cheers,

 

Graham