Leadership Team RogNeedham Posted August 12, 2006 Leadership Team Share Posted August 12, 2006 according to my last dyno results I'm losing 40+ hp between the two. how can I retain more of this loss - different gearbox for example 🤔 set up is 193hp Xflow - std Ford 5spd box - 15in prisoners with 195/45 CR500s or is this type of loss typical and i'm stuck with it Rog 🤔 Link to comment Share on other sites More sharing options...
rgrigsby Posted August 12, 2006 Share Posted August 12, 2006 Uh-oh this is a mute point for a lot of people, the actual figure of 40bhp may not be entirely correct. It's more of a "guide". A different gearbox will help but I suspect 15-20% losses are pretty normal on a road car. Rob G www.SpeedySeven.com Link to comment Share on other sites More sharing options...
Normans_Ghost Posted August 12, 2006 Share Posted August 12, 2006 It can be up to 30% dependant on box, diff, binding brakes, wheel bearings, tyre pressures and probably another 20 items. BHP on a rolling road is a guide, nothing accurate at all. A dyno on a test bed wii give a good comaprison between engines - the same dyno, the same weather conditions etc. BUT remember it's not only about BHP and torque. If it was I'd be putting a 1000bhp lorry engine in my 7. Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here You and your seven to The French Blatting Company Limited Link to comment Share on other sites More sharing options...
EFA Posted August 12, 2006 Share Posted August 12, 2006 BHP at the wheels on a rolloing road is a completely meaningless figure. If you want to increase or reduce your losses, tighten or loosen the straps holding the rear wheels down on the rollers accordingly. Without knowing what your losses actually are at the time of making the power run (which includes energy lost in tyre distortion etc) as well as critical factors like the true RPM of your engine for given torque at the rollers, there is no way of providing any reliable form of power figure. K2RUM - The car of two halveswith a hole in the engine Link to comment Share on other sites More sharing options...
Normans_Ghost Posted August 12, 2006 Share Posted August 12, 2006 Didn't I just say that. Torque is a calculation from measured BHP, 5250 comes to mind. Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here You and your seven to The French Blatting Company Limited Link to comment Share on other sites More sharing options...
DaveMorris Posted August 12, 2006 Share Posted August 12, 2006 Though 193bhp from a x-flow is pretty good going really - esp if the 193 is the "at the wheels" figure and flywheel is 233 Link to comment Share on other sites More sharing options...
EFA Posted August 12, 2006 Share Posted August 12, 2006 Norman, BHP is calculated from Torque, not the reverse as you state. BHP is purely a factor of torque against time. BHP and torque are related by the formula: bhp = torque x rpm/5252 K2RUM - The car of two halveswith a hole in the engine Edited by - EFA on 13 Aug 2006 00:29:50 Link to comment Share on other sites More sharing options...
henry21p Posted August 13, 2006 Share Posted August 13, 2006 forgive the numpty question then, but how does that translate into the power/torque curves you see on RR and dyno results then? The two curves, even overlaying the peaks so they were to the same scale, don't match exactly. I'm assuming that the rollers/dyno measure just one of the figures and calculate the other? Also, in which case, how do cars have more torque than others whilst still exhibiting the same approx bhp? Link to comment Share on other sites More sharing options...
Graham Perry Posted August 13, 2006 Share Posted August 13, 2006 Rog YHM Link to comment Share on other sites More sharing options...
oilyhands Posted August 13, 2006 Share Posted August 13, 2006 Dave21p, Engines with the same horsepower might well have entirely different *peak* torque and indeed different torque at peak power since BHP is a function of torque and engine speed. Peak torque and peak power rarely occur at the same engine speed. An engine making peak power of 200BHP at 4000 RPM will be making more torque than an engine making 200BHP at 7500RPM. The maths show that engine number one is making ((200*5252)/4000 - 262.6lb/ft at it's peak power whereas engine number two is making ((200*5252)/7500) - 140lb/ft. Even engines that make the same BHP at the same RPM wont necessarily have the same *peak* torque valve although the chances are they will be broadly similar. Oily Link to comment Share on other sites More sharing options...
Normans_Ghost Posted August 13, 2006 Share Posted August 13, 2006 horsepower Common unit of power, the rate at which work is done. In the English system, one horsepower equals 33,000 foot-pounds of work per minute-that is, the power necessary to lift a total of 33,000 lbs a distance of one foot in one minute. This value was adopted by James Watt in the late 18th century after experiments with strong dray horses and is actually about 50% more than the rate an average horse can sustain for a working day. The electrical equivalent of one horsepower is 746 watts in the International System of Units; the heat equivalent is 2,545 BTU per hour. The metric horsepower (see metric system) equals 4,500 kg-m per minute (32,549 foot-pounds per minute), or 0.9863 horsepower. For more information on horsepower, visit Britannica.com. Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here You and your seven to The French Blatting Company Limited Link to comment Share on other sites More sharing options...
Myles Posted August 13, 2006 Share Posted August 13, 2006 The two curves, even overlaying the peaks so they were to the same scale, don't match exactly. I'm assuming that the rollers/dyno measure just one of the figures and calculate the other? Also, in which case, how do cars have more torque than others whilst still exhibiting the same approx bhp? bhp = torque x rpm/5252 Dave - the equation just says that the torque curve and power curve *must* cross at 5252 rpm - or there's b*ll**** about... Check any published graph such as mine here How Stuff Works isn't such a bad site to start with. Project Scope-Creep is live... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
AndyBooth Posted August 13, 2006 Share Posted August 13, 2006 Oww!! My Head hurts *eek* Do I have to understand this or can I just go out and drive Am I a lesser man for not understanding. 😬 Shiny Red with Black Bits. Photo's to prove it! Link to comment Share on other sites More sharing options...
Normans_Ghost Posted August 13, 2006 Share Posted August 13, 2006 Andy, you're more a man for admitting you don't understand it. Go and drive it, if it's faster than someone elses thats good and if it's slower thats not so good. If it puts a smile on your face then thats all you need. Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here You and your seven to The French Blatting Company Limited Link to comment Share on other sites More sharing options...
AndyBooth Posted August 13, 2006 Share Posted August 13, 2006 With a 1.6K it's faster than some, but slower than most, but it always puts a smile on my face 😬 This does leave lots of room for upgraditis Shiny Red with Black Bits. Photo's to prove it! Link to comment Share on other sites More sharing options...
Leadership Team RogNeedham Posted August 13, 2006 Author Leadership Team Share Posted August 13, 2006 thanks guys...thought I might be opening a can of worms 😬 Dave (Morris) - if only ❗ the 193 was at the flywheel - not on the road as you say Norm - it's more than fast enough for my limited capabilities......time to invest more on the driver me thinks. I'm with you Andy - only understood some of the technical explanations Rog Link to comment Share on other sites More sharing options...
Colin Mill Posted August 13, 2006 Share Posted August 13, 2006 Straight cut gears will presumably reduce the losses compared to the standard helical gears but I don't know by how much. I guess you weigh the cost of this against the cost of getting more power at the flywheel. Link to comment Share on other sites More sharing options...
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