SLR/VHPD - Rev limit/Maximum Speed, etc ?

[SLR69]

I did a track day at Goodwood on Friday and at 125 mph on my Stack the Caterham speedo was showing 150 mph which shows how far out the latter can be.

 

My Stack system (ST500) has four change up lights and when the fourth one comes on I was doing 125 mph but the car was still accelerating with the usual frenetic energy with no sign of topping out.

 

Maximum power from the original Caterham brochure is shown as 7,500 which is 100 revs above where I was changing but is that the maximum revs ?

 

I have tried looking for a post on Blatchat and 7,600, 7,800 and 8,000 revs has been mentioned but seems no definitive answer.

 

Also is there a rev limiter fitted ?

 

I am trying to work out if my final gear change warning light is coming on at 7,400 at 125 mph, how the car is supposed to get to its maximum of 140 mph ?

 

Edited by - SLR69 on 25 Nov 2007 10:09:29

 

Edited by - SLR69 on 25 Nov 2007 11:35:04

[Matthew Willoughby]

See here

 

[SLR69]

Matthew thanks for the link which links to the Minister website and mentions many K Series engines but not the VHPD engine.

[Markiebabes]

Hi

your rev limiter is built into the ECU (thats where i found mine as i didn't seem to be hitting it 😳 ) not sure as to max speed as my stack is about 3mph out at 100mph (according to sat nav) first light on shift lights lit

may be worth going on to

MBE web site and downloading there software and see if you can access your map parameters 😬 think it shows shift light setting on there

 

Edited to say :-Thats if you have an MBE 😬

 

 

Mark

 

Car Webshots Here

 

 

Edited by - markiebabes on 25 Nov 2007 11:54:33

[CageyH]

Look here. PTP set the limit to 7,800. I set mine to 8,000 hard limit, and 7,900 soft, with shift light at 7,600.

 

Only dead fish go with the flow....!

[davef]

SLR69 - do you have MEMS or MBE ECU on your SLR? I wouldn't be surprised they were set differently. For reference on my ex race R400 engine the soft limit was set to 8000, with hard set set to 8050 (that's MBE ECU).

 

Dave

[SLR69]

Dave,

 

Its got the original MEMS ecu and the 4th and last shift light on the Stack ST500 comes on at 7,400 revs and that is what I had been changing up at assuming that was max revs.

 

However, I was hitting 125mph at these revs and assumed that there was no rev limiter and that's when I should change (well to prolong the life of the engine anyeay) but of course thought that the car should be faster than this.

 

However, the CC original sales brochure gives 7,500 revs as the maximum bhp, so I now realise that the 4th light isn't the rev limit and it somewhere between 7,400 and 8,000 revs.

 

Is there a soft and hard rev limit built into the standard MEMS ecu ?

 

I suppose the answer is to drive it beyond the 4th shift light and 7,400 revs and see if a rev limiter comes in.

 

Stuart

[davef]

Stuart, other MEMS equipped engines (e.g. the 1.6K Supersport I previously owned) have ECU rev limiters so I would expect the same with yours. Unfortunately don't know what it would be set to. The ST500 shift lights will be separately programmed and independent of the ECU settings - 7400 is just what someone has set it to.

 

Dave

[Jason Plato]

just simply drive it through the gears onto the rev limiter and then look at what your tell tale tacho says

 

you need to get a GPS or sat nav to check the accuracy of your stack and speedo - both may be wrong ?

 

determine your max revs on the tell tale and then half that ......drive down the motorway and see what speed half revs actually is .

 

Taffia rear gunner

 

[CanAm]

Stuart,

I have a 1600SS with a Stack ST500, and as Dave says, the 4 lights can be individually set to whatever limits you choose. On mine the hard rev-limiter cuts in at 7600.

Not knowing the wheel/tyre size, diff ratio etc for an SLR it's hard to comment, but somebody did post a very useful chart on here which lets you input tyre size,gear and diff ratios and then shows actual speed at various revs in each gear. If you can't find it using Search, drop me a blatmail and I'll send you a copy.

If you think the Stack is showing the wrong speed, is the tyre diameter programmed in correctly?

 

Alan

_{The existence of chance is everything and nothing whilst the greatest achievement is the living of life.}

[Andy Best]

I have a home brew VHPD none SLR car, it has Caterham 6 speed box, 3.92 diff and 205/60 rear tyres. I have set the electronic speedo against my GPS and plotted the max speed in each gear, if I set the rev limit at 8000 I will hit a shade under 138 in 6th, dropping the rev limit to 7400 would only see 127 this suggests that you have a similar gearing set up to me. Worst thing is limiting to 7400 you are losing over 10% of the available power according to my dyno plot 😔. This may explain why yours still going strong 😬.

 

The same V max speeds using a 3.62 diff are 138 and 150 respectively, oh and by the way when my engine was on Dave Walkers RR he reckoned the engine was good for more than 8000 rpm, but its a Scholar block, Vibration Free balanced and DVA built so not quite out of the box. I run at a rev limit of 7600 most of the time to prolong the life of the engine but know I can go into 'race' mode at the flick of a switch with the latest version of emerald ecu .

 

Hope this info helps.

 

Andy

[SLR69]

Thanks for all the comments but particularly yours Andy as this confirms my thoughts now as 7,400 revs = 125 mph so getting to 7,800 to 8,000 revs would be getting to somewhere in the region of 135mph+.

 

Interestingly no one has actually advised what the rev limit is on the SLR/VHPD is as standard ? Other cars with the VHPD engine, i.e. Elise, Exige, etc seem to mention 7,800 so I assume the same on the Caterham SLR ?

 

As Dave says I will have to give it a run and find out I suppose !

[Andy Best]

Sorry SLR spec in caterham sales brochure 1999/2000 show max revs as 8000 but with shift light at at 7400. May explain the myths. This set up had 3.62 LSD and 140 top speed. That would give about 140 at 7400 - 7500.

 

Andy

[jimmyslr]

I think the answer to your question is 8000 revs was where the rev limit was set on your MEMS, giving a v-max in mid 130s. I have proven both of these through usage!

 

Those last few hundred revs are quite hard on the engine and so people often use a lower threshold in practice, as evidenced by the revs at which your change up lights have been set by the previous owner.

 

Those of us with Emeralds (and I guess MBEs?) can vary the rev limit as the ECUs are programmable, unlike the MEMs. I have mine set to 7800 these days.

 

Regards, James