I seem to remember reading somewhere that the hotter cam on the vtec engine is best through almost the whole rev range. Apparently, it’s such an aggressive cam that it would suffer excessive wear at low revs. This is why the other cam is used.
Of course, I might be talking out of my arse
I leave cam change until 6300 which seems to produce a nice smooth curve (> http://elise-r.co.uk/mambo/images/stories/johnboy.jpg> ) but scuffers pulls it in lower and with some careful mapping produces a good result.
Johnboy, you’re taking the piss on us right?
Your power is good, but the changeover is really shite. The shitvic crowd would be proud of your car
Looks to me like your changeover point is waay too high
I leave cam change until 6300 which seems to produce a nice smooth curve (> http://elise-r.co.uk/mambo/images/stories/johnboy.jpg> ) but scuffers pulls it in lower and with some careful mapping produces a good result.
Johnboy, you’re taking the piss on us right?
Your power is good, but the changeover is really shite. The shitvic crowd would be proud of your car
Looks to me like your changeover point is waay too high
So what do you find “shite” about it?
I’m with Uldis, I thought you were joking
It’s pretty obvious there’s a huge step at the cam changeover. You’d get a MUCH better spread of torque if the cams switched much earlier.
Happy to dig out graphs of what happens when you push it out earlier - basically you tend to produce real fueling dificulties after the change in cam angle. Also remember the cam change is quick but its not a switch and it does have lag so you end up with predeictive fueling and ignition and chasing your own tail.
You do incerease the overall area under the graph but end up with a very choppy curve - its this choppyness that produces the vtec “kick” beloved of the boy racers. That produces horrible results in a lightweight car - on mine you can feel it in the sense of “have another 20ft/lb” but thats all.
Scuffers has managed to bring it down and still keep it sensible but with the ECU he uses he gets facilites I just don’t have - he uses a mondified honda ECU, I use MoTeC M800 series with Cam angle control.
Basically - its a trade off, less you can have a better “spread” but that does not equal a better curve epsecially when it comes to actualy driving the thing.
Basically - its a trade off, less you can have a better “spread” but that does not equal a better curve epsecially when it comes to actualy driving the thing.
Think that’s the nail on the head there, everyone’s getting very passionate about graphs, graphs do not hack round circuits and if it “feels” right for him then good on ya!
We all know this, from tyre pressures to a wee bit of camber to just what coffee you have before you go out on track
If it works for you then it works
Fair enough, Johnboy. It’s always easy to look at graphs and numbers and make assumptions, but theory doesn’t always fit the practice.
So what do you find “shite” about it?
Ok, it was already discussed, and I don’t know the problems you have, different ECU’s Simon having a different one, different software.
To me, if he has achieved a better changeover, it is possible, so if I was you I’d be looking into getting there.
Meanwhile, I really think that curve will give you an unneeded (at the track) kick in the pants.
Hey, some people like it, but I would be fighting it.
I just posted this on the Seloc forums so I thought I might as well put it here as well, as I have been keeping an eye on these threads for a while now…
Well, this is my first post but I have been following the ‘King K’ threads on Exiges.com for the last few weeks and a few of the posts on here… I like to keep an eye on the Lotus world!
Simon E kindly sent me his article in Word format today as I live out in America now and I can’t really get hold of racecar engineering easily.
It was a very good piece and very interesting. There is nothing Earth shattering there but equally, he is probably the first person to have really researched it and then put it down in writing for the world to see. I cannot really see any inaccuracies and there is no new theory… But when you put it all together and understand the original weaknesses, it does make sense that a reliable K series engine can be built.
If the car comes with a K series, and you can get a reliable 200bhp+ out of the K series for less money than a conversion giving the same power… Then why not do it! Time will tell whether this is worthwhile… If Uldis et al get some miles done in their cars and report back we will see.
It amazes me that so many people have slagged off Simon’s work when he is doing it to help people. Why have a go at him if you don’t have an interest in selling something different?
I don’t know Simon or Uldis and I don’t own an Exige, however, I am somewhat uniquely placed to comment as I was part of the original Motorsport Elise development team in '99 and the worked as an engineer for Lotus Motorsport during the horrific first season in '00. After having to change up to 10 engines a weekend and having drivers scream about reliability and all the in-fighting it caused… I went back to University to get my second engineering degree… And start fitting cars with lovely, reliable bike engines.
However, Simons work has given me a new outlook on the K series. After our first season I would slag off the K series to anyone that would listen and up until a few weeks ago I still did… I will be wandering around with my tail between my legs if (and hopefully it will) Uldis’s car turns out to be reliable.
I have nothing against the Honda etc… In a way (not meaning to open a can of worms) it is a better engine and I studied several SAE papers on it’s design and was truly fascinated (in a sad way) about some of the development that went into it. But 10k for a conversion is crazy money and if you can drive your Exige/Elise in somewhere, have the engine built to Simon’s spec for the same power/torque as the Honda for something like 5k…
Goodbye honda…
It does make you question why some engine builders seem to do so little research… All our engines were built by Minister and they simply could not fix the HG problem… And, didn’t ‘seem’ to produce the 200bhp they were meant to… Doesn’t mean they are not a good outfit, and all they guys were really cool… It is just interesting that a member of the public has taken the time and effort to research it properly and publish it… Yet he still gets shouted at!
From my point of view… I have studied enough engineering to know what should work and what shouldn’t… I always have my engine work done to my spec by a guy called Matt Saville who works for QEP ‘down south’. I would never risk giving an engine and an open cheque book to a company without knowing what they were going to do and wholly understanding it. The simple fact that people still quote cylinder head ‘stages’ as if you can compare one persons stage 3 to anothers is crazy…
Anyway, rant over! I say good work Simon E! Now, lets see how long those engines last!!
Regards
Dom
Dom,
Welcome! and nice to meet you.
Very sensible post, fair and positive remarks.
It’s an honour to have part of the Lotus MS team with us in this BB.
I am trying to use the car every day now but unfortunately it’s winter and sometimes it’s difficult with the ice and snow.
But (as I did before) will be on as many track days as I can next year, and will be entering also some of the Scottish Sprinting races and som Hillclimbs.
Will put it to good use.
Hope to see you around some more, don’t be a stranger.
It’s an honour to have part of the Lotus MS team with us in this BB.
Thanks Uldis! But, I was just a young man when I was doing all that, so I’m not a lot older now!! Thankfully wiser!
I will pop in from time to time, I’m more active on the technical 205 GTi site http://forum.205gtidrivers.com/ where we are often in fairly heated debate about all matters tuning…
But all things engine and tuning related interest me, so I’m sure I will keep an eye on this forum!
Best of luck
Dom
"and if you can drive your Exige/Elise in somewhere, have the engine built to Simon’s spec for the same power/torque as the Honda for something like 5k… "
Sadly though you can’t - mine has cost me to date under 5k and can only think of a couple of NASP K’s in elises that could match it and they cost a lot more to make.
Its great to see you over here - please post up more of your experience (both MS lotus and bike engined stuff - do you know sinclairs are threatening to put a V8 bike engine in an elise?)
See, Johnboy, your conversion, they way you went at it, under �5K, makes sense.
We could still talk about weight and balance, and what it does to the car, but at �5K it’s worth it.
So I guess the infamous �10K is one of the pivotal points around the argument.
If you think about it though - thats just commercial relalities - as Gain points out over on Seloc, Simon E does not do this full time for a living. If you go and get a commercial honda conversion in a nice big specialist garage then you pay for the whole turn key approach. And fettling with an existing engine is always going to be cheaper.
And if you have to dry sump the thing to get the power Simon E is talking about that isn’t particulary cheap and as a DIY proposition is not that easy I believe.
So how much would that lot cost at a commercial specialist sports car garage?
And replacing the manifold etc . . .
Not sure when you add that in, even as a DIY proposition, its not getting close to the cost of bennards audi-nutter conversion. And there its another turnkey proposition backed up by Bernnards engineering skills.
So like for like, apples for apples, DIY to DIY, to date Simon E = 209/140, honda 240/166.
Good point.
But if I’m already thinking that any replacement I do to the car it’s got to be with a lighter part and I’m already struggling with the idea of the little weight that the Honda engine adds, imagine what I think about the Audi
No way I would add that much weight. Yes, it’s got the power, but I’m all about balance.
Heck! I’m already thinking the Exige is too heavy and suffers too much throwing all that weight around, and am toying with the idea of a bike engined kit car!
Or get a knackered Elise just to build a lightweight one.
But then, we’ll see. There’s this house that my wife, the kids (%& me) are really keen on…
pah - leave the house and figure out how to get that RV8 twin bike V8 into the back on an elise.
you know you want to .
John,
Sincs are doing it now… But it’s not a v8 bike engine (I know of no such engine ) but 2 R1 heads, pistones and conrods on a custom crank on a custome block…
But figures are impressive, apparently ~300bhp revving at about 14k and weighs ~70kg fully dressed
Absoluely mega if it comes off!!!
Absoluely mega if it comes off!!!
As will the price be! But I guess there’s no such thing as a free lunch.
Ian
You pays ya money and all that, if you want a f3 engine then you pay for one
It does make me wonder tho… The new ZX-10 Engine (998cc) pushes out 185bhp from the factory with nothing done to it, ok so rev’s to 14k or something silly but is still v. powerful! If you think you could tune one of these up (MSS Kawasaki are making their SBK engines now) and get more like 250bhp with RamAir why couldn’t you run one of these?
They weigh about 50kg, 6 speed sequential box, no flywheel, balanced blah blah blah… Just about 3ftlbs of torque so you’d need to rev the nuts off of it just to get it moving
I have seen parts of the Radical bike V8 when I was driving a Radical up at Bruntingthorpe a few weeks back. I have been following this project from the early nineties and I have a cut out from an early 90’s copy of ‘fast car’ with a picture of a bike V8 made from two Yamaha 5v FZR1000 blocks and heads.
This is what led me to look at the FZR1000 and eventually I ended up with a short stroked screamer produccing around 140bhp… Peanuts nowadays but great at the time.
There are effectively 3 bike V8 type engines available or almost available to buy… The most developed at the moment is probably the Cyclone, then there is the one being developed by Quaife/Radical (but I think Mick Hyde has bought out the Quaife part) and another one which I can’t think of off the top of my head but they were featured in one of the last issues of CCC.
I see no reason why one couldn’t be used in an Exige and it is certainly something I have thought about. I was thinkinbg that there wouldn’t be a transverse installation for the cyclone and the other one, but the Radical is actually designed to be mounted transversely and comes with an appropriate gearbox… So, I see no reason why this should be any more difficult to transplant than say an Audi turbo engine. It will also come in up to 3.2l and produce in excess of 400bhp… How does that sound? But… It will porobably cost over 30k installed with the gearbox etc etc…
Ouch… That’s like 2yrs drinking and stripper money!
I think the Radical engine has it’s own block but the others are usually two Yamaha blocks and heads bolted onto a common cast crank case… Very obvious really, I’m surprised it’s taken them this long to exploit it!
As for sharing my experience at Lotus… Well, let’s just say I enjoyed every minute in a way but I would NEVER go back to working for a race team, in the pits anyway! I was sharing a room with ex F1 driver Martin Donnelly one night and he was like “Dom, work in an office, you don’t want to work in the pits… It’s a f*cking hard life”… Oh, how right he was! Still, had we had a k-series that stayed in one piece for more than 5 mins then life would have been easy, the drivers would have been happy and the series would have survived!!
We had just one engine last the whole season and that was Pat Charlton’s… He was also the slowest guy on the grid and took it easy… Everyone else had at least one engine, some people maybe up to 5!!
