Can you rev small engines the same as bigger engines?

[GreigM]

hora said:

Or a middle ground

be as well taking the bus then

[Kozy]

hidetheelephants said:

Kozy said:

I have a small engine. I hate my rev limiter, it ruins all my fun stops me ventilating my crankcase with my conrods for gofasterness.

EFA

As eni fule knos, ventilated crankcases are soooo much faster.

Disagree, the B16B is more than capable of revving past the stock limit as standard and with the uprated valvetrain in mine it should be capable of around another 1000rpm over the stock 8600rpm limit.

That's taking into account the piston accelerations, weights and forces too.

So yes, it spoils my fun.

[C2james]

Petrolhead_Rich said:

Pah, keep the current car, you just need an upgrade:

I've seen that before, its fantastic, I'd like to put a V6 in my car next year but really need a slightly bigger car. Also the insurance would just be stupid.

[CraigyMc]

deveng said:

How high an engine revs is not a function of displacement, but of piston mass, stroke, and number of pistons. Take a v10 formula 1 engine, approximately 20 000 rpm from a 3.5l, because it has light pistons that don't have to travel far.

Heavy pistons increase the force it takes to accelerate the piston, reducing max revs, having a large stroke increases piston speed for a given number of rpm, increasing the accelerations on the piston, reducing max revs and the number of cylinders affects the volume of each cylinder for a given engine volume, which has implications of piston mass and stroke.

I know this is totally offtopic but:
The last of the 3.5 litre engines didn't rev to 20K - they would have been about 16,000rpm (in V12 form) by the close of the 1994 season (which was the last time we had 3.5l engines). The v10's would have been lower than that.

The 3.0 V10's got up near 20K - in 2006 they would certainly have been over 19000rpm, but none of the manufacturers ever publically released any information about speeds over 19400rpm (toyota). It's quite likely that some of them did faster.

The 2.4 V8's (2006, before revlimiting came in) certainly exceeded 20,000rpm. C0sworth published a video of a 20,000rpm dyno run. BMW were rumoured to be well over that figure privately.

C

[deveng]

CraigyMc said:

I know this is totally offtopic but:
The last of the 3.5 litre engines didn't rev to 20K - they would have been about 16,000rpm (in V12 form) by the close of the 1994 season (which was the last time we had 3.5l engines). The v10's would have been lower than that.

The 3.0 V10's got up near 20K - in 2006 they would certainly have been over 19000rpm, but none of the manufacturers ever publically released any information about speeds over 19400rpm (toyota). It's quite likely that some of them did faster.

The 2.4 V8's (2006, before revlimiting came in) certainly exceeded 20,000rpm. C0sworth published a video of a 20,000rpm dyno run. BMW were rumoured to be well over that figure privately.

C

I bow down to your superior F1 engine knowledge!

I was however just trying to prove a point that big capacity by no means guarantees high revs.

[Globs]

doogz said:

Rev limits are generally there to save the head, no?

Things like the PSA TU, the bottom end will happily rev to 11k all day long, it's opening and closing the valves that determines the rev limit.

I'm not sure really, I think everything in an engine should be engineered so it all goes at the same time - else some bits will be too heavy..

[WeirdNeville]

You drive to an engines individual strengths.

My 1.6 Toyota 4AGE you revved like bloody hell when pressing on. They were balanced by hand at the factory and were built to rev. They made all of their power at the top end and sounded great doing it. On trackdays it was between 5,000 and 7,500 rpm all day long (after warming up) and didn't miss a beat.

The 2.8 Straight six BMW engine has a load of low end torque (though still not on a par with a TDI for example) so you can waft along and use the flexibility of the engine in circumstances where a smaller engine might require a down shift or two. It'll still rev high, but the nature of the engine doesn't encourage it.

My wifes 1.3 Mazda makes no power or torque anywhere. You just have to rev it to accelerate, and it really feels like it wasn't built to do it.

Drive to the strengths of the engine, but as power = torque x rpm, and a higher gear always reduces the force the wheels are putting to the road, if you've got a smaller engine you simply have to rev it more to make adequate progress on occasions.

[CraigyMc]

deveng said:

CraigyMc said:

I know this is totally offtopic but:
The last of the 3.5 litre engines didn't rev to 20K - they would have been about 16,000rpm (in V12 form) by the close of the 1994 season (which was the last time we had 3.5l engines). The v10's would have been lower than that.

The 3.0 V10's got up near 20K - in 2006 they would certainly have been over 19000rpm, but none of the manufacturers ever publically released any information about speeds over 19400rpm (toyota). It's quite likely that some of them did faster.

The 2.4 V8's (2006, before revlimiting came in) certainly exceeded 20,000rpm. C0sworth published a video of a 20,000rpm dyno run. BMW were rumoured to be well over that figure privately.

C

I bow down to your superior F1 engine knowledge!

I was however just trying to prove a point that big capacity by no means guarantees high revs.

Totally agree with your point anyway - in fact, the biggest engines of all only turn over at 102rpm...