does everyone`s else`s do this?

[RemarkLima]

Mine does it, I didn\'t think it did but then pushed a bit harder and it does... It\'s just a shame you\'re normally whizzing past any speed limits at the sound of the beep.

But speaking of rev limits, where does the ECU cut in a hard limiter? 8,000 rpm? And how safe is it to take it to the limit ona  pretty standard car? My old MR2 I\'d take to 8,000 rpm in every gear, but being N/A you have to give it loads of welly just to keep it moving!

[iaint]

Mine does it, I didn\'t think it did but then pushed a bit harder and it does... It\'s just a shame you\'re normally whizzing past any speed limits at the sound of the beep.

But speaking of rev limits, where does the ECU cut in a hard limiter? 8,000 rpm? And how safe is it to take it to the limit ona  pretty standard car? My old MR2 I\'d take to 8,000 rpm in every gear, but being N/A you have to give it loads of welly just to keep it moving!

These cars seem happy with redlining BUT be careful in 4th and 5th if you\'re approaching the limiter...  Not because you\'ll got to prison, lets assume you\'re doing it on a private road/runway...

In 5th approaching 7krpm you\'re doing ~150mph, maybe a little more.  Your car is under peak load which increaces massively from wind resistance.  Air and water temps will be rising rapidly and EGT temps will be stellar.  Your turbos will be glowing!

This is a great part of the ECU\'s map to show up weaknesses and tiredness in components - fuelling. cooling, injectors, plugs, etc.

Even a well sorted motor can go pop under these conditions.  Mine did a week last Sunday at 161mph and it has all the right fuelling, spark, intercooler and rad mods in place!

Puching it in 1st-3rd should be okay for most cars though!

[Bobfish]

Hitting the redline is fine. I do it all day every day in mine, its great fun.

At hitting the redline in 5th? oooer- i think that equates to over 200mph my friend. I know that you can do circa 150mph in 4th!

[Red and Single]

Interesting point Iain.....

I\'m simplifying things here, but on boingers, engine stress is said to square with revs or something like that, i.e. 8K gives a so called "stress factor" of 64 compared to 7K\'s stress factor of 49.... a massive difference.

I wonder of this is true of the rotary engine too ??

Either way I never go over 7500 rpm.....no point for me anyway my porting and turbo arent made for high revs.

[RemarkLima]

Thinking of it like that, it\'s pretty impressive! To be fair, most engines can go pop at that point really

But I can only think of Bedford Autodrome and Snetterton (except a few airfields) where you\'d really be hitting those speeds... Oh, and Germany

Where were you doing 161 mph???

[iaint]

Hitting the redline is fine. I do it all day every day in mine, its great fun.

At hitting the redline in 5th? oooer- i think that equates to over 200mph my friend. I know that you can do circa 150mph in 4th!

Don\'t trust your speedo

Passing through timing beams at Bruntingthorp (looooong runway!) speedo was showing well over 185 and the beams read 172!

The gearing on a manual FD will hit the standard rev limiter setting ~185!

Of course and auto diff with it\'s longer ratio (3.9 opposed to 4.1) will do the trick I think!

[iaint]

Where were you doing 161 mph???

Bruntinthorp proving grounds...

161 was the final (fatal run).

Managed 172 and 169 on the previous two runs.

Prior to the T70 going on the standard twins could push me to 156 before everything got too hot and they ran out of puff.  With WI I reckon I could get the car to 8k rpm.  Going to see if I can source an auto diff for next year!

[Jono FD3]

Nutters, The lot of you!!!!! Cant afford to brake mine, so I\'m not going to be doing any monster driving with it....... apart from the odd 911 now and again...... his face was funny!!!!

Think the standard limiter kicks in at 8k as mine was popping & banging in second all lit up out of a junction, as there was a truck coming to get me!!!!!

Jono

[rmagictastic]

In 5th approaching 7krpm you\'re doing ~150mph, maybe a little more.  Your car is under peak load which increaces massively from wind resistance.

QUOTE]

 peak load is in 4th at approx 5.5 k i believe

Rmaj

[RemarkLima]

Bruntinthorp proving grounds...

161 was the final (fatal run).

Managed 172 and 169 on the previous two runs.

Prior to the T70 going on the standard twins could push me to 156 before everything got too hot and they ran out of puff.  With WI I reckon I could get the car to 8k rpm.  Going to see if I can source an auto diff for next year!

Wow! Impressive stuff! Shame about the engine death...

As R&S says, I wonder if the stress factor goes up? It sounds like it goes down with more revs

[iaint]

Just done some maths based on the following numbers...

Diff ratio: 4.1:1
5th gear ratio: 0.719:1
so
Final drive: 2.9479 (diff * 5th)  (a)
Tyre diameter: 25.327"  (b)
RPM: 7000 (c)

MPH = (b*c) / (336 * a)

or

(25.327 * 7000) / (336 * 2.9479) = 179mph

8000rpm should give 204mph.

An auto diff (3.9:1):
7k: 188mph
8k: 215mph

Assuming ample power to get you there!

I\'ll be looking for an auto diff then as torque declines as rpm rises - one wants to be geared to maintain speed in the torque/power band.

[Bobfish]

Feed are doing a 3.7 diff at the moment.

226mph at 8k!
240mph at 8.5k!

woot!!!

[iaint]

You\'d need > 1000rwhp to get there though!

As I said - more interestes in the longer ratio to help me keep the rpm down when going for speed.  To keep in teh peak torque band.  Where did you find out abouthte feed diff?  How much?

[Initial-D]

Much as I like going top speed in the FD I still find accelatration more fun. 160 is the quickest mines been (I showed that R34 lol)!! All on a runway of course.

[Initial-D]

A 3.7 diff would certainly make your acceleration a bit slower though. I\'d rather have a 4.7 and lose the top end.