kenton
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| posted on 16/6/08 at 08:49 PM |
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RV8 max rpm?
Hi,
does anyone know what i can rev my rv8 to safely for any length of time?
In 5th gear i can do 130 mph at approx 5thou rpm and am wondering at what speed wind resistance will overcome power. (i have a full screen fitted)
thanks kenton
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BenB
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| posted on 16/6/08 at 08:53 PM |
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Wind resistance will never truly overcome power but the amount of power required to drive a very draggy car will just be unfeasably high!!!
Most sevens (with screen) max out at about that speed (or before!) regardless of power:weight, diffs, tyres etc etc. The cD of a Se7en is not good
despite not having any aerodynamic aids (the classic example being a Lambo Countach has the same cD as a VW minivan due to all the aero (on the
Lambo!!!)....
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BenB
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| posted on 16/6/08 at 08:54 PM |
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Quoth Wikepedia (well it might be right one of these days...)
"....While the car's frontal area is small, the Lotus Seven has the highest drag coefficient of any known production car--ranging from
0.65 to 0.75, depending on bodywork...."
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robinj66
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| posted on 16/6/08 at 09:02 PM |
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If you have standard valve springs/lifters etc i think you shouldn't be doing more than 5,500 rpm for any length of time
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Agriv8
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| posted on 16/6/08 at 09:10 PM |
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as far as I understand from what I have read I have deduced.
Std cam and lifters will not let you get much more past 5.5 k
Uprated cam ang hi rev lifters may get up near 6k
But anything above 5.5 and you need to ensure that
a) bottom end is cross bolted
b) it has been ballanced
Hope that helps
Regards
Agriv8
Taller than your average Guy !
Management is like a tree of monkeys. - Those at the top look down and see a tree full of smiling faces. BUT Those at the bottom look up and see a
tree full of a*seholes .............
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kenton
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| posted on 16/6/08 at 09:20 PM |
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Its an ex twr (Tom Walkenshaw Racing) engine so its not standard! but i dont know what has been done other than re-bore, larger valves and ports.
It "feels" as though it has more to give but dont want to damage anything.
kenton
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Simon
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| posted on 17/6/08 at 12:22 AM |
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As AgriV8 says. The hydraulics will pump up when you get around 5500rpm and won't let you go any higher (in theory at least). If you have non
standard lifters or solid lifters (ie you have to adjust tappets) then engine may go higher.
But then, if it's been "built", no reason why you shouldn't see 7000rpm from it. Try it at your expense though
Of course the best thing to do, is get a really low ratio diff, a pair of turbos and you won't need to exceed 5500rpm
ATB
Simon
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v8kid
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| posted on 17/6/08 at 10:05 AM |
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Standard crank even if lightened, ballanced and with lightweight con rods etc will go at 7k. best set rev limiter to start soft cut at 6.5k with hard
cut at 6.75k.
Depends on cam profile if you will get any power though!!
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Agriv8
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| posted on 17/6/08 at 10:20 AM |
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quote:
Originally posted by kenton
Its an ex twr (Tom Walkenshaw Racing) engine so its not standard! but i dont know what has been done other than re-bore, larger valves and ports.
It "feels" as though it has more to give but dont want to damage anything.
kenton
In that case two options.
talk to the engine builder they may be able to advise. ( if they keep the records )
or
Take it to a rolling road that have a good knowlege of the V8 and see where you get you peek RPM most rover v8 power curves I have seen drop of
quickley after peek BHP set you limiter accourdingly.
BUT you could still end up vibrating it to death. What I am saying is just because it can get there does not mean it will stop together.
saying that I suspect that V8's are going to get a lot cheeper if fuel keeps at this price !!!!
regards
Agriv8
Taller than your average Guy !
Management is like a tree of monkeys. - Those at the top look down and see a tree full of smiling faces. BUT Those at the bottom look up and see a
tree full of a*seholes .............
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