Down on power - R500 Vmax at Bedford?

[Walton]

Hi

I'm convinced my recently acquired R500D seq is down on power - it just doesn't seem as urgent at higher speed/revs as my R500D H-box I owned previously - despite having an aeroscreen which my older car didn't. I know the gearing is much taller with the seq box (65 in 1st), and obviously a helmet mutes things a bit but acceleration feels very slow after 120mph.

I was at Bedford the other week, and although peak speeds were a respectable 140mph on the long straight, my mate in his brand new R500D seq SV was hitting identical speeds (on the SPA telltale) despite:

Me being a significantly faster driver on stickier rubber
Him running a windscreen versus my aeroscreen
Him running aprox 10% more weight (SV + heater + leather chairs and extra 25kg combined driver & pax)
Me running restrictive carbon airbox versus him foam.

I called up in-gear acceleration times from the following trackday at Rockingham with the foam air filter and it showed there was no difference in performance between it and the carbon airbox at Bedford. In my old car - there was a very noticeable difference (albeit in a bit warmer temps).

Caterham say the car feels fine, and have checked for the throttle position sensor which caused problems on my last car. At a guess I'd say the car feels 10% down on power.

Can any advanced drivers let me know what Vmax they get at Bedford in an R500, as I think this would help settle things. Failing that I suppose a dyno.

Cheers

Rich

[chris_speed]

Again?! Searched and found your old thread: http://www.pistonheads.co.uk/gassing/topic.asp?h=0...

I'd get a RR session done, see how much power it's (roughly) down by. If they're worth their salt, they could find the problem anyway.

[Dave J]

I don't think your the first to comment on varying power between R500D engines

do a search or post on blatchat for some other owners views

[David Long]

There are others on here that are better qualified to comment on the R500, but my rebuild of my R400 showed there had been a significant slip in valve timing. It's relatively easy to check so worth adding to the list. Although I did other work at the time, I think putting it right cured several engine problems and up'd the power, particularly at higher RPM.

[mic]

A significant slip, how many degrees?

[David Long]

mic said:

A significant slip, how many degrees?

The inlet was between 2 and 3 degrees out. The exhaust was OK. Bearing in mind that these are set up with a tool that locks them in the right place, I concluded that it must have slipped in use. I under stand that friction washers can be fitted to reduce this problem but, as far as I'm aware, the CPT engines don't use them . Maybe some of the engine guys can tell us more.

[Walton]

Thanks. Other prob turned out to be a maladjusted throttle sensor by the airbox. This has been checked and it's ok.
I've said to Cat that'll i'll cover the cost of the dyno if it's found to be fine.

[mic]

Only the R300 engines are set with the bar, the diamond back washers are not required with the R400 cams.

[edb49]

Hi Rich, I'm going to Rockingham on 14th Nov with the Vbox, so I'll get lots of data for in gear times to compare then. My car is a bit heavy (leather seats, heater, 13.5st driver) but otherwise should be as quick as an R500 can be.

Remember the R500 SV has an aero disadvantage from enlarged frontal area.

[Walton]

Cheers Ed. If the weather's nice I may join you.

Here's some Vbox footage from when I was there the other week: http://www.youtube.com/watch?v=1XmrY06h6V0

[mattmurdock]

No idea on the potential power loss, but just wanted to thank you - I was taken out in your car by Dom on a visit to Caterham South, so I could see the difference between the racing suspension upgrade and the normal suspension. As it was already a customer car, he gave you a bell for permission - so I guess I have you to blame for the extra cost

Have to say it felt pretty good on the run up the Caterham bypass, easily as quick as the other car I tested that day - but we didn't get above 120 (officer).

[mic]

I've just read David's write up about fitting the dry sump, rather than correcting the valve timing it appears he set the the cams up with a bar. R400 cams should be set using a dial gauge.

[David Long]

mic said:

I've just read David's write up about fitting the dry sump, rather than correcting the valve timing it appears he set the the cams up with a bar. R400 cams should be set using a dial gauge.

Yes, you are right! I did ask Caterham about it but they weren't forthcoming with the data and said this was the way to do it. The end result was an improvement but I accept that it might not be the optimum. Anyone got the correct data for The R400 cams?

[edb49]

Walton said:

Cheers Ed. If the weather's nice I may join you.

Here's some Vbox footage from when I was there the other week: http://www.youtube.com/watch?v=1XmrY06h6V0

What tyres were you running there out of interest?

[Nicodema]

Come on ed, hit the "more" button

Few fast laps from Rockingham International on 30/10/10 in a Caterham R500 Duratec with sequential gearbox & Avon ZZRs.

[Walton]

Yep - ZZRs. Really great tyres.

How are you getting on with yours Martyn?

[Nicodema]

They were awesome at Cadwell, but we haven't had any track time since and what little road time we've had has been on the 15" CR500 setup. I notice your bonnet went north at speed! I bet that was moment and a half. Is that new bonnet time?

[Walton]

Nicodema said:

They were awesome at Cadwell, but we haven't had any track time since and what little road time we've had has been on the 15" CR500 setup. I notice your bonnet went north at speed! I bet that was moment and a half. Is that new bonnet time?

Nope - remarkably it's only got a few grazes at the edges - lucky.

[edb49]

Yep, must say I'm pretty impressed with the G-forces the ZZRs were getting. No doubt a bit of handy driving too! Will be interesting to see how my knackered slicks compare...

(Sunday is forecast to have a few showers though :|)

[edb49]

Can't be any help I'm sorry to say, it was wet all day yesterday so the most I got down the straight was 110mph. There's something about Rockingham that makes it super-slippery when it is wet, I'll post up a video of the sideways hilarity soon.