Discussion
So as not to hijack porschesteve's thread too badly, I thought I'd start this up here...
Last year I was considering an engine upgrade in my standard chassis 7. Engine of choice was to be the RST V8.
A number of things outside of the car arena have caused me to put these plans on the back burner, but they are still there to be actioned at some point.
fergus has posed the question about whether an RST equipped car would be quicker than an "Ammo" 300bhp Duratec, which brought me back to one of my "concerns" about such engine upgrades.
Is all that power wasted to a greater or lesser extent in a 7?
My concern here is that there's a limit to how much power the car can actually put down on the road. Having been out in the RST SV, it's happy to spin its wheels in the dry in most gears. It's an awesome, awesome machine. But once the wheels are spinning, there's surely little point in having the power...?
Traction control can be (is) fitted, but ultimately this isn't letting you re-write the physics rule book, it's simply cutting the power to the wheels that are losing traction...
Wheel arch extensions etc will allow ever wider track at the back, and ever wider rear tyres, but at what cost the handling purity of the car? Straight lining is not what I want from a 7.
So how much power is enough in a 7? I have some ideas here, and think it's probably in the 200-250bhp ball park.
I will, at some point, fit an RST V8 in the car I'm sure. The noise, and most inportantly the weight saving over the other available options is not to be sniffed at. And it'd be nice to have another 8cyl car in the garage. The quality of Russell's work is also second to none. Truly amazing engines.
But the power question still bothers me...
PS To me a lazy torquey engine is also not what 7s/sportscars are about. Lazy engines are for GTs. Cars designed to be thrown around need screamers. They need you to have to think and interact with the car....sorry for verging on a rant. What says everyone else?
Last year I was considering an engine upgrade in my standard chassis 7. Engine of choice was to be the RST V8.
A number of things outside of the car arena have caused me to put these plans on the back burner, but they are still there to be actioned at some point.
fergus has posed the question about whether an RST equipped car would be quicker than an "Ammo" 300bhp Duratec, which brought me back to one of my "concerns" about such engine upgrades.
Is all that power wasted to a greater or lesser extent in a 7?
My concern here is that there's a limit to how much power the car can actually put down on the road. Having been out in the RST SV, it's happy to spin its wheels in the dry in most gears. It's an awesome, awesome machine. But once the wheels are spinning, there's surely little point in having the power...?
Traction control can be (is) fitted, but ultimately this isn't letting you re-write the physics rule book, it's simply cutting the power to the wheels that are losing traction...
Wheel arch extensions etc will allow ever wider track at the back, and ever wider rear tyres, but at what cost the handling purity of the car? Straight lining is not what I want from a 7.
So how much power is enough in a 7? I have some ideas here, and think it's probably in the 200-250bhp ball park.
I will, at some point, fit an RST V8 in the car I'm sure. The noise, and most inportantly the weight saving over the other available options is not to be sniffed at. And it'd be nice to have another 8cyl car in the garage. The quality of Russell's work is also second to none. Truly amazing engines.
But the power question still bothers me...
PS To me a lazy torquey engine is also not what 7s/sportscars are about. Lazy engines are for GTs. Cars designed to be thrown around need screamers. They need you to have to think and interact with the car....sorry for verging on a rant. What says everyone else?
murph7355 said:
My concern here is that there's a limit to how much power the car can actually put down on the road. Having been out in the RST SV, it's happy to spin its wheels in the dry in most gears. It's an awesome, awesome machine. But once the wheels are spinning, there's surely little point in having the power...?
Uwe Altzen must have the same problem in his 700hp 911 'Ring monster!
murph7355 said:
And it'd be nice to have another 8cyl car in the garage.
murph7355 said:
PS To me a lazy torquey engine is also not what 7s/sportscars are about. Lazy engines are for GTs. Cars designed to be thrown around need screamers.
Agreed. If it delivers anything below 6k rpm, it doesn't suit the character of the 7 IMHO (strimmer engines excluded!) I think if you had a MoTEC M800 or a decent ECU controlling the motor and hooked up to accelerometers and wheel speed sensors on each wheel, you could have a hell of a package, allowing, as you say, the max power to be transmitted to the road, physics constraints accepted.
It would be worth it for the sound alone, assuming a well designed exhaust and loads of overlap! Or does the RST run with a flat plane crank?
murph7355 said:
So how much power is enough in a 7? I have some ideas here, and think it's probably in the 200-250bhp ball park.
I'd say 200bhp @ 8000rpm suits a lightweight Caterham perfectly. As you point out, I'm not sure that it is possible to effectively utilise much more power, unless you're a straight line junkie.
I'm much more a fan of driver training, handling optimisation and weight reduction (in that order) as effective means of going faster on track.
Can't recall if it's flat plane or not. IIRC it is, but stand to be corrected. Started life as two bike engines glued together, but is oh so much more than that now. Amazing engineering.
Anyway, I'm a flat plane crank man. They sound unbelievable at 9k revs And the RST engine goes well beyond that (10.4k+).
The traction control fitted to the RST demo car is pretty good as it stands. I just wonder how much of that power ever gets to the tarmac.
Agree with jeremeyc on going quicker.
I'l be doing the upgrade (eventually) on the premise of weight The engine's even lighter than a K (possibly by as much as 15kg).
Anyway, I'm a flat plane crank man. They sound unbelievable at 9k revs
And the RST engine goes well beyond that (10.4k+). The traction control fitted to the RST demo car is pretty good as it stands. I just wonder how much of that power ever gets to the tarmac.
Agree with jeremeyc on going quicker.
I'l be doing the upgrade (eventually) on the premise of weight
The engine's even lighter than a K (possibly by as much as 15kg). 
fergus said:
where do max power and torque occur? What sort of figures does the engine produce? I've heard figures of 345hp quoted!! How much are they, approx £12k or so?
Details here: www.rst-v8.com/fergus said:
...approx £12k or so?
I think that's for the 2l. And it's +VAT. And + exhausts and a whole bunch of other stuff that would be needed.
They're not cheap, but you simply have to see the quality of engineering in these to understand where the money goes. It's so many light years ahead of an R500 type of engine, or a Duratec that the money is secondary. Unless you need to pay for one
Depends what you are interested in, learning to drive or just having an ultimate caterham and lots of power for monster oversteer.
In 4 years of caterham trackdays not once have i come across a trackdaygoer who drove even *vaguely* close to a proper R400 race qualifying time. They only have 200bhp, that is all you need.
Learn to drive that first and then once you can genuinely claim to make sub 50s at BHI, 2.40 at spa, sub 1.50 at oulton etc.. then maybe think about more power. Only then will the difference in BHP be truly meaningful.
If on the other hand you are interested in just owning something pleasing, talking pub figures and holding on for dear life down the straights then by all means go for an RST.
all IMHO
In 4 years of caterham trackdays not once have i come across a trackdaygoer who drove even *vaguely* close to a proper R400 race qualifying time. They only have 200bhp, that is all you need.
Learn to drive that first and then once you can genuinely claim to make sub 50s at BHI, 2.40 at spa, sub 1.50 at oulton etc.. then maybe think about more power. Only then will the difference in BHP be truly meaningful.
If on the other hand you are interested in just owning something pleasing, talking pub figures and holding on for dear life down the straights then by all means go for an RST.
all IMHO
murph7355 said:
jackal said:
...
Agree with you in terms of general sentiment...
The question is though, is there physically any point in having an engine that chucks out 250, 300, 400, 500bhp etc in a 7...assuming, for the sake of the question, that the driver is Ayrton Senna (etc).
Whilst you are seriously up against teh law of diminishing returns, the bottom line i guess is that more power means you'll munch the straights up quicker so yes, senna would make a quicker lap. But how soon before that power increase also means a weight increase or an unfavourable weight distribution and you start going backwards laptime-wise ? Who knows....
230bhp in a series 3 seven and straight line wise you are faster than many race tintops and single seaters, radicals etc.. If you want to travel any quicker then its really time to address aerodynamics and suspension/chassis to reap proper benefits. e.g. CSR's 1.12 at donnington
I have a 2.0 YB in mine.It is turbo'd and charge cooled etc etc yap yap...
It is not as light as an R500.It probably wouldn't put a lap in as fast as one either.Do i care.No.Is there a point?No.It's a hugely fun car, has masses of torque,is as docile as you want it to be, for the sedate days,and as bonkers as you like for when the feeling arises.And also it is extremely reliable too.Having come from 1000cc bikes,inclduing a breathed on R1,this car was, IMHO, the only thing that would give me that same kick that a bike would.
Bottome line is, each to their own!
See you out there sometime
It is not as light as an R500.It probably wouldn't put a lap in as fast as one either.Do i care.No.Is there a point?No.It's a hugely fun car, has masses of torque,is as docile as you want it to be, for the sedate days,and as bonkers as you like for when the feeling arises.And also it is extremely reliable too.Having come from 1000cc bikes,inclduing a breathed on R1,this car was, IMHO, the only thing that would give me that same kick that a bike would.
Bottome line is, each to their own!
See you out there sometime
I don't think 300bhp/230lbft is "too much" power. Certainly it's well into diminishing returns, but you can still get enough power down to make a big difference on corner exit. Of course, to go quicker it's last on the list of sensible upgrades, but it's still right up there as a "fun" one!
I've a range from 100-200 bhp on road and track, and my ideal seven would have a revvy, lightweight engine of about 150-170 bhp. The original 133bhp Superlight is one of my favourites and when I get one again it may be that model, unless I race again. It's a horse for courses thing really, I prefer to feel I'm driving the car to the absolute limit than to feel like I'm hanging on. When I was racing there were very few cats at trackdays that would come past me or any of the lot I was racing with, and that was with 115bhp, an open diff, the standard brakes, and road legal tyres. Plenty of them had 200bhp and all the toys. But some people love the rush of pure acceleration and don't want to be on the true limit in braking/cornering - in which case good luck to them - if we were all the same life would be dull!
I, too, like revvy engines in cats, not lumps with big torque. I have a friend about to assemble a 230bhp duratec cat, will be interesting to see what it is like and whether it changes my mind!
I, too, like revvy engines in cats, not lumps with big torque. I have a friend about to assemble a 230bhp duratec cat, will be interesting to see what it is like and whether it changes my mind!
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