cheapest power to weight?

[Tight fart]

my old smoky crossflow is due for a freshen up.

Is it worth speding money on it or should i change the engine for something else.

bottom line is it must be as quick as a SLR.

 

so is it bike engine or zetec, or do up the crossflow?

 

T.F@O.F

[dino ferrana]

Bike power would get you the pace of the SLR but depends what you go for. I don't think you could get a Crossflow to match a SLR at least not reliably. No experience with Zetec so couldn't say much about it. You may spend less overall on putting a new engine in but you will get very little of this back if you sell. May make better overall sense to trade in and go for something quick as standard (used SLR). This way you spend more but have a better value asset at the end of it.

 

Just a though

 

Dino

[Tight fart]

trade in is not an option,

i built her 13 years ago!

[murph7355]

I suspect going from where you are that the best "keep" option will be a Zetec. Don't know enough about them to give you any more than that ...

 

The SLR isn't just quick because of its engine however. Stuff like suspension set up, weight, gearbox, LSD and brakes all have a big part to play. And if you're lacking any of this stuff you'll need to upgrade it to give you a chance of out-SLRing the SLRs.

 

And that will be expensive. In this case I'd trade up.

 

Call me odd but I'm not sure about the bike engined thing. There are lots of compelling arguments, but my car's predominantly road based which I don't think suits. I can't help thinking that if you want bike engined power, a bike has to be the thing to buy?

 

 

[Drumster]

If you want to upgrade the x/flow then speak to Roger King first.

 

He'll do a 140, 155 or 185bhp rebuild for you depending on what you want the car for. Contact Roger on 01992-421111 or visit his website here. You'll find Roger very knowledgable and won't push you down any particular route, just leave you to make your mind up.

 

No connection; just a very satisfied customer.

 

Chris Alston

 

Se7ening - it's all miles and smile.gifsmile.gifsmile.gif

1800 Supersprint - Loud and Proud teeth.gif ...well it only sounds fast officer blush.gif

[groutledge]

I'm not convinced that an SLR engine is stronger than a crossflow. Having seen a K with the head off off down at the 7 workshop, they seem to be built using an egg box and 4 liners, the head bolts are very weedy. A Crossflow seems to have much more sructural integrity over a K and a friend of mine runs his his all steel xfow to 8500rpm no problem. Nasty clutch though, as you aproach 8000rpm you have to go to a paddle clutch which are not nice.

 

I dare say the K-brigade will chime in soon but I'll bet all those knocking out 200bhp-ish have had a few blow-ups. I know SLR-500 motor is a bit of a grenade as well.

 

Having said that I ran an Elise 190 with that engine and it seemed Ok for the year or so I had it, it drank oil though. My 155bhp RK engine doesn't use a drop! they're not cheap though but you get what you pay for!

 

 

Graham

[Bangers quotNquot Mas1697456953]

"the head bolts are very weedy. "

[Bangers quotNquot Mas1697456953]

"the head bolts are very weedy. "

[Bangers quotNquot Mas1697456953]

"the head bolts are very weedy. "

 

Graham, if the K does have a weakness it's definately not here!

 

I've now owned both types Q56 RNV Jondel x/flow (pain in the a..)

W7 VHP VHPD K series. The K is in a different league!

 

The argument that it looks like it's made from "egg cartons" doesn't stand up, take a look at a DFV against the latest offerings within the world of F1, which is better? Ancient castles had walls 8 feet thick to stop cannon balls, I've no doubt using modern design techniques and materials we could achieve the same results with 6 inch walls.

 

It's an evolution thing...

 

Sorry about the mis-postings!!!

 

 

Edited by - beagle on 2 Apr 2002 07:35:40

[Rob Walker]

The liners on the K`s do look flimsy but the facts are there have been very very few failures. Most of the reliablity problems associated with the K are due to the cooling and not bleeding all the air out of the system. lubrication is another as the engine is installed on an angle the engine suffers from oil retention in the head this is compounded by poor drainage back down to the sump. The oil pump also causes a lot of aeration of the oil. Reliablity is definately improving as more developement takes place, the Satur uprated head gasket is one example. Steel head dowels another.

[murph7355]

Let's not also forget that the XF has been around for 30 years (or more?). How many of these were kicking out 110+ bhp/litre in the early days without a few problems (or at all)?

 

*Any* engine giving that sort of volumetric efficiency is going to need to be looked after.

 

Your 155bhp XF may not be causing you any grief, but then it's only knocking out 90ish bhp/litre if it's a 1700. My 1400K was giving this sort of ve without any issues too. You have to compare like with like.

 

Yes I own a K, but I'm not blind to the issues that can be had with it in high output form (far from it!). To say it's any worse than any of the other engines without considering all the inputs is daft.

 

If I were debating getting my car to be as quick as an SLR there is no way I'd be looking at a XF, no matter how much I think they are nice engines that sound absolutely lovely.

 

 

[EFA]

Crikey, The K now having difficulty justifying superiority over the Xflow.... Whatever next??

 

Fat Arn

Visit the K2 RUM siteid=red>

See the Lotus Seven Club 4 Counties Area Website hereid=green>

 

[edmandsd]

Tuned crossflow every time.

[oilyhands]

So you'll be putting one in your Caterham to replace the BD..? :) There's no way a xflow can get within a country mile of the torque curve from even a mildy tuned K series. Show me a *reliable* 1800 xflow producing over 200BHP at reasonable RPM with good torque spread and I'll be convinced, otherwise its all just hot air.

 

Oily

 

Edited by - oilyhands on 2 Apr 2002 10:23:38

[V7 SLR]

Hear hear Mr Hands.

 

Staying with the crossflow and using the justification that it's a stronger engine than the K is talk from the Flat Earth Society.

 

That a strong enough defence of the K, Arn? wink.gif

[murph7355]

Arn - I was going to say that even putting a Vx in would be preferable. If you must stick with weighty 30yr old engines.

 

I wonder what we'll all be deriding in 20yrs time smile.gif I'm off to design a 2l short stroke V12 that will fit snugly in our favourite engine bay...now where are those '50s F1 books I had lying around.

[edmandsd]

Oily,

 

My HT Racing 1825cc x/flow showed 199bhp at the flywheel (175bhp at the wheels)on Sanspeeds rolling road at 7,000 rpm with kent 264 cam and large 4>2>1 manifold. Powered 700kg Mk 1 XR2 Fiesta from 0 to 100mph in under 12 seconds and was unbeaten for 5 years. Same engine in 550kg Sylva did 0 to 100mph in under 10 secs. Take a good k to beat that !

 

Point is if someone's got a car with a crossflow already fitted they can get strong k performance using existing engine.

 

My motto is when the flag drops the bull**** stops so I can't be accused of being full of hot air.

 

In terms of reliability the only problems I encountered over those 5 years was the requirement to sleeve an ax block with an 86.5mm bore and a knocked out steel 272 cam as a result of trying out zero viscosity oil.

 

Edited by - edmandsd on 2 Apr 2002 13:02:35

[oilyhands]

Show me the torque curve from the engine, then compare it with a similar output K series, a two valve engine needs shedload more cam to achieve similar HP outputs to a 4 valver, an 1800K can make 200BHP from 274 degree cams , a 264 is 310 degree cam with a quoted power band of 5000-9000.

 

You dont get the massive torque hole you would see from a crossflow at that level, you can also achieve this output from a *virtually standard* VVC head, a pair of cams and TBs.. The torque curve from Lorne Masons home modified 1800K series shows peak torque of 154ft/lb with over 130ft/lb available from 2500 to 8300 thats 85% of peak torque available for over 5500RPM..to match that sort of torque curve from a 2 valve would be next to impossible and this engine was put together in someones sapre time with a bit of guidance on the head mods on a virtually stock bottom end.

 

Its a rare and expensive crossflow that makes more than 180BHP.

 

Oily

 

Edited by - oilyhands on 2 Apr 2002 13:20:38

[edmandsd]

I accept your points Oily and don't pretend for a moment that ultimately a 2 valve per cylinder engine can compete with a 4 valve per cylinder engine in terms of max power. However, even without the torque curve to hand you'd have to accept that a crossflow with 199bhp at 7,000 rpm must have plenty of torque inorder to achieve such high bhp at relatively low rpm. HT Racing are always looking to maximise area under the curve, not just top end power (as we all should).

[oilyhands]

It will have precisely 149ft/lb at peak power :-), the issue isnt really whether it makes torque, but where it makes it and how wide the usable torque envelope is.

 

This is where a 4 valve engine has its biggest advantage, it doesnt need a lot of cam to make big power.. hence it can sustain its torque through a wider RPM band.

 

I have a particular couple of plots from a mildy modified K series making 170BHP and a 165BHP 1800 crossflow, the K series torque at 3000RPM is just about double that of the xflow and it is ahead significantly until 5000RPM where it drops to only only 5% ahead, above 6500 it is way ahead again. These were taken on the same RR on the same day. Given the choice of a lighter, more powerful engine with a wider torque spread I know which I would choose.

 

Oily

[cdg]

Stick a Hurley Engineering Mazda rotary in it. It's compact, has no valves, no cams,no cylinders (!) is turbine smooth, sounds wonderful, has no reliability issues these days, and no-one else will have one. It weighs about the same as a x-flow (which I think is one of the best 2-valve 4cylinder engines ever made) and can be mated to the Ford gearbox very easily. 200bhp is dead easy, 250bhp is not difficult but requires some very special porting. It can be run on carbs or injection.

 

Before the objections start flooding in, I know that it's very loud, has appalling mpg (who gives a toss about that!) and needs to be revved hard to keep it in the power band; but for me those are reasons for having one!

 

Right, you can start objecting now...

 

Chris.

 

 

 

[Paul Turner]

I have resisted replying to this thread so far but since my old mate Chris has now put in his five pennies worth I have to reply by law.

 

I had been running a pretty good x-flow flow for 8 years, all steel 1800 (revved to 8400), various flywheels, various cams, weber alpha ignition by Roger King since 98, gave 143 @ wheels RK's figure (probably 170 at the flywheel), very reliable (once I had the block machined flat) but it was not all that pleasant on the road. All the parts for the above (mostly 2nd hand) plus machining plus labour probably came to £3000 originally. Won lots of sprints/hillclimbs in mod prod and roadgoing, stills holds the upto 1800 record at Curborough in 58.52

 

Have now fitted a 2 litre Zetec, total installtion including all parts, engine, Kent cams, VAT etc came to approx. £3000. Its on the rollers on Friday but it pulls like a train from 2000 to 7000 rpm, cruises at 1500 rpm in 5th and is much quieter. Doing a sprint at Curborough next Sunday, will then have a better idea how it compares.

 

I will tell you in 8 years time which was the best value, there ain't nothing wrong with a x-flow though.

 

Paul

[cdg]

Paul,

 

I like playing Devil's Advocate...

 

£3000 will get you a very, very good rotary, and apart from porting,new tip seals, improved carburation , and a free-flow exhaust it's all virtually stock.

 

May come and watch at Curborough. I like a good laugh!

 

Chris.

 

[DohNut]

It is unusual that the 6th reply on the second page (Pauls) actually answers the original question most closely. From the starting point of a tired x-flow what is the best direction to move in bearing in mind with any new engine instalation you will have to spend such a large proportion of your budget on stuff like sumps alternators starters engine mounts etc. I would be interested to see an accurate pricing of a xflow to K conversion, if it really is the cheapest way to reliable power I am interested smile.gif

 

oops boss on the phone - must go

[cdg]

PS

 

As an aside, my mate's Chevron ate another Hart 420R at Donington last week. He found 2nd instead of 4th and 12000rpm is a bit much even for a Hart. It had just been rebuilt aswell! Estimated rebuild cost this time is "only" £4000-£5000. These old four bangers are a liability- far too many moving parts for my liking!

 

Makes a compelling argument for sticking in a rotary (which he's seriously considering).

 

Chris.