Guest Posted August 21, 2014 Share Posted August 21, 2014 I'm looking to get DVA Power to upgrade my R300K to R400 spec. Taking it from 160bhp to around 200bhp will obviously make the car quicker but presumably unless I change the rear diff ratio the top speed will be the same? There is a difference between a car being quicker and a car being faster - they are two different things. One of the reasons for investing all this money is to give me a higher top speed on some of the circuits that I do track days on. Am I correct in what I'm thinking or will Dave's upgrade add to the top speed by virtue of the fact I'll be able to rev it higher? What are your thoughts/input? Many thanks, CycleSi Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 21, 2014 Member Share Posted August 21, 2014 What's the rev limit before and after the conversion? Do you currently hit the rev limit in top? Jonathan Link to comment Share on other sites More sharing options...
Guest Posted August 21, 2014 Share Posted August 21, 2014 The rev limiter is set at 7250 at the moment. I'm just waiting to hear back from Dave about what I'll be able to rev it to after. Link to comment Share on other sites More sharing options...
Titanium7 Posted August 21, 2014 Share Posted August 21, 2014 Rev limit will depend on the upgraded internals of the engine. Link to comment Share on other sites More sharing options...
oilyhands Posted August 21, 2014 Share Posted August 21, 2014 Around 7900. That should add around 10% to your top speed. Oily Link to comment Share on other sites More sharing options...
Paul McKenzie Posted August 21, 2014 Share Posted August 21, 2014 Find a calculator like this on line and all will be revealed CR 13 INCH WHEELS mph circ rpm ratio final drive mph/1000rpm 51 5.40 7250 2.39 3.62 7.1 80 5.40 7250 1.54 3.62 11.0 102 5.40 7250 1.21 3.62 14.0 123 5.40 7250 1.00 3.62 17.0 141 5.40 7250 0.87 3.62 19.5    CR 13 INCH WHEELS mph circ rpm ratio final drive mph/1000rpm 56 5.40 7900 2.39 3.62 7.1 87 5.40 7900 1.54 3.62 11.0 111 5.40 7900 1.21 3.62 14.0 134 5.40 7900 1.00 3.62 17.0 154 5.40 7900 0.87 3.62 19.5  Edited to add: my final drive is 3.92. 154mph - no thanks  Edited by - Paul McKenzie on 21 Aug 2014 20:24:11 Link to comment Share on other sites More sharing options...
A10ROX Posted August 21, 2014 Share Posted August 21, 2014 Also ... max speed reached at max revs, do you have sufficient power to pull max rev in 6th gear R400 on Caterham map requires a pull or downhill to reach max ... Achieved twice max 140mph So many benefits in more power Link to comment Share on other sites More sharing options...
Guest Posted August 21, 2014 Share Posted August 21, 2014 I'll be happy enough if it will do 140 mph. I guess I'll just leave it to Dave and The Two Steve's to do their magic !!! Link to comment Share on other sites More sharing options...
Z3MCJez Posted August 21, 2014 Share Posted August 21, 2014 Higher profile tyres = higher top speed (if the car can reach the rev limit in top). Jez Link to comment Share on other sites More sharing options...
elie boone Posted August 22, 2014 Share Posted August 22, 2014 Apart from the extra power, an aero screen will definitively help you with the top end. Link to comment Share on other sites More sharing options...
Area Representative peewee7 Posted August 22, 2014 Area Representative Share Posted August 22, 2014 Remember Dave doing my upgrades... shortly after I ditched the screen for an aero, hey presto I had all new braking points due to the lack of wind resistance...brake upgrade next... One improvement leads to another! Link to comment Share on other sites More sharing options...
TomGaval Posted August 22, 2014 Share Posted August 22, 2014 Speaking of top speed, here is an old MIT video re: aero/drag. Realizing that our whole car is a brick, do you think the drag from the roll cage is significant, and do you think the addition of something like this would reduce drag enough to be worth the cost? here Always looking for another couple MPHs to keep up with the GT3's and Zo6s on the straights. Tom Edited by - TomGaval on 23 Aug 2014 00:09:35 Link to comment Share on other sites More sharing options...
Chris Cardwell Posted August 24, 2014 Share Posted August 24, 2014 Tom.  The lecture on drag was fascinating it would be better to start with a car which is more aerodynamic  It would be interesting to compare top speed of the Seven, Elise, Exige, Zenos (when available)  Thanks Chris Link to comment Share on other sites More sharing options...
TomGaval Posted August 24, 2014 Share Posted August 24, 2014 Chris, I assembled my Caterham 14 years ago and just bought another one. 😬 So I'm stuck with them. My new one has A lot more HP (309) and is cycle fendered and vs my Clammed (195hp) one is ALOT quicker and has a higher top speed, but I seem to still be about 10 to 15mph short of the Vettes and GT3's down the straights. Yes, I do have an advantage coming out of the turns and in the braking zones, but it's just frustrating having them run me down after working so hard to put some distance between us. An extra 2-5mph would be nice. Just looking for options besides loosing more weight. 😬 Tom Link to comment Share on other sites More sharing options...
MarcNS Posted August 24, 2014 Share Posted August 24, 2014 Top speed is interesting. if you take a standard 7 with a windscreen is there a terminal velocity after which no extra power will make a difference to top speed?       Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 24, 2014 Member Share Posted August 24, 2014 *arrowup*No. Power needed to beat drag goes up as cube of speed. At high car speeds nearly all the marginal power goes on drag. What's the fastest recorded speed in a 7? Jonathan Link to comment Share on other sites More sharing options...
charlie_pank Posted August 24, 2014 Share Posted August 24, 2014 Alternatively, add some lightness and be another 100yds further away after each bend! Link to comment Share on other sites More sharing options...
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