cheapest power to weight?

[Big Brother]

I think your all missing the point!

No matter how much cash you throw at a K series.....It will never sound as good as a crossflow teeth.gif

 

Steve

www.Se7en-Up.co.uk id=green>

 

[Peter Carmichael]

Oily,

 

Thanks for stepping in to defend me. My comments were not tongue in cheek. The electronic medium was not at fault either. My comment was qualified and was incompletely read. It was not that "Dave is a perverse little man, per se" but that "Dave has demonstrated perversity by constructively misconstruing my meanings". He did so again in detecting outright insult in my post.

 

Insult was not meant, nor written.

 

How about: "Dave is a wind-up merchant and knows that to tug my chain all you have to do is pretend not to have read my words"

[AMMO]

Original question was "Cheapest Power to weight".

 

Option 1: Upgrade X-flow.

Option 2: Zetec

Option 3: Bike engine

Option 4: K-series

 

Say you have 3 grand to spend

 

With the X-flow weight stays the same. The power goes up. You don't have to buy engine mounts, re-route stuff etc. Relatively stress-free conversion. It still is an old lump of cast iron with pushrods. I personally don't like them that much because they are noisy and they drive me nuts on a long journey. Some people like the noise, the flames and the bad fuel consumption.

 

With the Zetec there are a few more complications. The 1800 is cheaper than the 2 litre to buy as a second-hand unit and has the benefit of a lighter flywheel and the water pump turning the right way. You have to change the engine mountings and starter motor also. So less money to spend on engine internals. However the head with a bit of porting flows a lot more than a Crossflow ever will. The power goes up but so does the weight, by about ten kilos in my case. Got all of it back by fitting an ali bell housing, lighter starter motor and battery. With the help and advice from people on this forum the conversion was relatively easy.

 

Bike engines. My personal opinion is that if you spend your 3K in this direction is that you would end up with a very nice track car that you could have a lot of fun in. I personally would not want one for every day use as again the noise would drive me nuts after a while. Also I'd be a bit concerned about the longevity of the gearbox. The lack of weight has to be the biggest draw for this one. The ease of conversion will be dictated by whether you want to make all the bracketry, shafts adaptors yourself or buy them in from someone who already makes them. To be truthful I don't actually know if this coversion can be done for 3K.

 

Converting to K-series seems a bit daft. Must be easier to sell the X-flow and buy a K car.

 

So which is the right option? Whatever you prefer. Each conversion has it's supporters. The Crossflow, Zetec and bike engine people all have their reasons for liking what they've got.

 

Best thing to do is get a ride in all of them. When you lie awake at night lusting after a particular car, that will be the right decision for you.

 

AMMO

[V7 SLR]

I support your theory on converting to K. It is a better bet to sell up and buy a K and that's exactly what I did, however I don't support your theory that you can convert to a bike engine for 3K. I know someone who has done it recently and was over 5K. You have to remember that a reverse box is nearly a grand, all the bike engines are around 1500 now and then you've all the other problems that you'd be lucky to solve for 500 quid even if you did them yourself.

 

That said, you may get a decent amount back on your crossflow and gearbox to help support the outlay. If this is possible I'd say a bike engine is the best conversion. I've seen a Zetec head recently and was amazed at how small the valves are even when compared to a K, but I accept that it has more potential than a crossflow, but even that's not a "cheap" conversion really is it? I think the Zetec's appeared to be a better conversion when I thought they could be dropped straight into the hole left by a crossflow. Now I have realised the effort required to fit it, I'm not so sure.

 

... and then again, I've had chance to hear a couple in action over the last year, and like them enormously... but they don't evoke the kind of ear-to-ear grin that the bike engine's cars did when I first saw them. And I'm someone who hated the idea of them originally... now I think they're marvellous, although tainted by their escalating prices.

 

There... how's that for sitting on ALL the fences? smile.gif

[AMMO]

So that exludes the bike engines as a cheap option then.

 

The standard valves in a Zetec are 32 mm inlets and 28 mm exhausts. This makes them bigger than a stock VVC K Series and a lot bigger than the stock 1400/1600 ones. My Zetec valves are one mil oversize at 33 and 29. I also had some 34 mm intakes made at the same time but didn't want to go to the trouble of putting bigger valve seats in.

 

If properly sorted, both the VVC and Zetec head have the same approximate potential for airflow and horsepower. So not a lot to choose from there then.

 

The K is lighter but the Zetec with it's cast iron block doesn't have liners that jiggle around.

 

Although the Zetec doesn't just drop in the hole the Crossflow leaves, it is pretty damn close. I think it is the logical conversion for an aging Zetec. So do James Whiting, Raceline and Dunnell's for that matter.

 

My conversion came in at a lot less than 3K but I get everything trade and did all the work myself. Sold the old engine which helped to pay for things like ali bellhousings etc. I think it is possible to do the conversion for 3K, possibly less if you shop carefully.

 

Not one single owner who has gone Zetec that I've spoken to has regretted it. But then I suppose that none of the bike engined car owners have regretted going their route either.

 

 

 

 

AMMO

[JP]

Don't know how much it costs but I was just looking at the Caterham Canada (BC) website. They advertise a SV with Hayabusa engine. "Up to 340 hp available" is the claim. Sounds like fun.

James.

[edmandsd]

The rpm, power, torque for my 1825cc crossflow (5 years ago on 48 dcoe's) was as follows:

4116,85,109

4345,95,115

4574,105,120

4802,114,125

5031,118,124

5260,136,135

5488,148,142

5717,162,149

5946,170,150

6174,175,149

6403,179,147

6632,185,147

6860,193,148

7089,196,145

7318,198,142

7546,199,138

7775,197,133

8004,191,125

8232,186,119

[murph7355]

My relatively mildly tuned 1800K gave 200bhp at 7450rpm or so (and was flat from there up to 8k) and 155lbsft torque lower than 6k revs (I have the curve somewhere at home but it was nicely filled out).

 

It's on pretty wimpy cams that are lovely around town and revs like a nutter. I also like the way it sounds (others have also commented how good it sounds).

 

I've never drag raced it against the clock, but as it weighs about 505kg I would imagine it'd do OK in the aformentioned test assuming my LSD, gearbox and tyres were comparable to those in the XF car...

 

It's just had a bit more head fettling so might have a bit more power and torque too (and it's being mapped on a dyno so the figures should be spot on - though the ones just mentioned are highly likely to be very accurate).

[Peter Carmichael]

Andy, There is an email doing the rounds where I have plotted the Dave's crossflow against your K. I will forward it.

[Paul Turner]

My Zetec has now been on the rollers (see page 2) and the figures achieved are exactly as expected. Its a bog standard 63,000 mile 2 litre with a pair of FZ2002 cams, the corrected flywheel figure was 179.5 @7000 rpm (I had hoped for about 180) but everything happens about 300 rpm higher than I anticipated, thats probably down to the headers being a gnats bigger diameter than normal. I was very impressed before the engine was set up compared to the old x-flow, now I am even more impressed, it drives absolutely bloody great.

 

I have plotted a graph showing the figures from the old 1800 x-flow (back in 95 254 spec, its the only one I have) and the Zetec and they are eerily similar, but the x-flow did everything about 750 later and peaked at about 175 bhp.

 

At Curborough yesterday my times were crap (put that down to new tyres buffed by mad Frankie Fraser and a very rusty driver) but the speed across the line (taken from the tach) was about 3 mph up on the 1800 x-flow, exactly what I expected from the power increase.

 

One very satisfied customer and at less than £3000 (the engine cost £150) fitted all in DIY, a cheaper way to 180 bhp with excellent drivability (its on 45's) I would like to find.

 

Paul

 

Edited by - Paul Turner on 8 Apr 2002 13:48:45

[murph7355]

Cheers Peter.

 

Hopefully there'll be a little bit more out of it very soon...

[DanB]

The prices of bike engines, especially the common ones for car installations like the Fireblade, Blackbird and Hyabusa engines, have gone up but compared to modified car engine and gearbox packages they're still cheap for the power you get IMHO. I've got a 'bird engine in my car which cost me £1500, and there aren't that many 170bhp engine and gearbox cominations available for that money.

 

A bike conversion for £3k is definitely possible although it would probably require some work. Fireblade engines are available for around £1,200 which would leave £1,800 for a manifold, gear linkage, engine mounts, rejetting kit, new propshaft with centre bearing, sump baffle and a bike fuel pump. Emminently possible, I'd say.

 

Get a Kwak ZX9-R engine for around £700 and you get extra power and a better 'box. OK, there probably won't be off the shelf manifolds or engine mounts, but you've got an extra £500 to play with.

 

Bike engined cars aren't for everyone but the downsides are much exaggerated. Noise? In my aeroscreened car the wind noise drowns out the engine at anything above 50mph, and that's with gearing at 10mph per 1k rpm. Reliability? It's a little early to say but so far these things have proved virtually bullet-proof. Lack of torque? Quite simply rubbish. There's an art to pulling away from a standing start but I drive mine round town quite happily - in fact it's easier to drive around town that my Pug 205 GTi!

 

The only downside to a bike engine is the reverse issue - pushing can become a pain and there are reliability problems with reversing boxes. The answer is electric reverse units but there are no commercially available ones so you have to be happy with a welder.

 

Dan

Furrybird Q660 KKL

[edmandsd]

I've got nothing against bike engines as they are on the whole streets ahead of your average car engine in terms of technology.

 

That said they don't have a lot of torque - 'It says it on the tin' What they do have is a lot of power and a very linear torque curve which with their very close ratio gears means you're experiencing most of that torque output most of the time.

[Peter Carmichael]

... and if you have less torque but at higher revs, you have your gearing set up with a lower ratio. For any speed that the slugalug car engine is at 4000rpm the bike engine has an equivalent gear that can keep the engine spinning at 6000rpm the ratio is lower; the torque at the wheels is 1.5 times as effective at the wheels as the bald torque figure would suggest. Each lbft of the bike engine's output is worth 1.5 times the car engine's output if it has 1.5 times the rev range.

 

This is where I keep banging on about power curves being the be-all and end-all of performance comparisons of engines. The comparison above, which combines consideration of torque with consideration of revs, has in effect compared power (power = torque * engine speed).

 

How is the above scenario giving both car and bike engine a fair fight? Well suppose we are talking about 60mph. The car engine revs to 8000rpm. The bike engine revs to 12000. From 4000 in fourth, the car engine driver will not need to take another gear until 120mph. The bike engine driver at 6000rpm will not need to take another gear until 12000rpm at 120mph. They both maintain the same gear ratios selected throughout the comparison; they both are forced to select new gears at the same speed.

 

The important thing in comparing outright performance of car and bike engines is how the power is developed in proportion to the rev range. It is not *peak power* that is important. If you plot the power curves of two engines against a horizontal engine speed scale that goes from 0(standstill) to 1(change up rpm), you can overlay any two engine plots and see a meaningful comparison of how fat the spread of power is - fatter the better. I have a spreadsheet which does this.

 

It doesn't matter whether it is a bike engine or a car engine, 1 litre or 4 litre, short stroke or long stroke; the comparison will be a fair indication of engine performance.

 

The comments that been posted about how drivable the bike engines are means that the low headline torque figure isn't an issue. They have a fat power delivery over a wide rev range so every lbft is worth 1.5 times the lbft you see quoted for car engines. (rule of thumb)

 

Edited by - Peter Carmichael on 8 Apr 2002 18:32:43

[DanB]

Peter,

 

Couldn't have put it better meself. The 'bird engine has a reduction gear inside the gearbox which is approx 1.5:1. I like to think of it as an engine which revs to 8k rpm but has 50% more torque throughout the rev range than the figures would suggest. Which ends up being quite a lot...

 

Dan

Furrybird Q660 KKL

[dogvet]

Having owned both BEC and CEC, I think the CEC is easier to drive and even my humble Academy car with AO32rs could keep up with a Westie Fireblade at Oulton park last month, despite being heavier. fully screened and less bhp.

[san]

£3k for an install is very easily achieved but don't tell everyone.

 

I have had a BEC for a year now and as all owners (bike powered or not) would never change back to anything else. Okay the figures point out the lack of torque but as Peter has written this, on it's own, does not = power. Also if you take your 140bhp bike engine and compare to normal engine do not forget that the bike engine weights include the gearbox the lot so there is a large saving there. We are talking cars weighing less than 420Kg all in here.

 

We all know that with a passenger in the car it is slower which will not be far off the difference in engine weights..

 

Plus you get the sequential shifts for free. But as has been said before, they are not everyones 'cup of tea' but they are fun just the same.

 

Simon

Striker-IRS CBR1000

 

[Graham Sewell]

Re-reading the original title for this thread - try Weight Watchers! Get the weight down first....

 

Low tech luddite - xflow and proud!

[charlie1]

changing the subject slightly, what could you do to a 8v vx graduate race car engine and how much would you spend, I've got a similar dilemer at the end of this year I will mod the existing engine or sell engine/box and go the fireblade route, this car would only be used for track days, would love some comments from anybody who is knowledgeable on the 1.6 8v vx.

[Graham Sewell]

On the 1.6 Vx engine, the 1st option would be 'upgrading' to the 1.8 SuperSprint. A different option would be to have the engine worked on by a Vauxhall specialist - Bill Blydenstien springs to mind (if he is still in the business).

 

Cheers,

 

Graham

 

 

Low tech luddite - xflow and proud!