Duratec porting, a few thoughts.

[paul jacobs]

Actually, I think most of us with only a very basic understanding of engine dynamics and gas flow etc find your thoughts more than interesting, and feel quite privileged that you have chosen to air your thoughts with us. Do keep them coming, we might not say much but we are here waiting for the next installment. 😬

[peterg]

this exactly matches my thoughts, I don't know much about the real technical stuff as to how good engines make their power and why but love reading about it so it increases my knowledge *thumbup*

[AMMO]

Giles

 

The inlet valve area can more or less determine the potential horsepower of an engine.

 

For years I have been using a simple calculation to give me some sort of idea what power the engine is likely to make. The information came in the Superflow flowbench manual when I bought my first flowbench in the late 80s. Basically you take the valve area in square inches and multiply that by the cfm (cubic feet per minute) the head is likely to flow. This will be somewhere between 50 and 60 cfm per square inch of valve area at 10" test pressure. In the early days of two valve engines I used to use the 50 cfm figure with time and experience I tend to go more towards the 60 cfm figure, especially with 4 valve engines.

 

If you take the case of the Duratec with stock 35mm inlet valves the valve area is almost 3 square inches of intake valve area and a well ported head makes 178 cfm. So pretty close to the 60 cfm per square inch figure. The problem with the head is that it makes maximum flow at something like 16 or 17mm lift. With more realistic lifts the flow will be less.

 

By taking the flowbench flow figure and multiplying by .43 you get the potential power figure per cylinder. Taking a more realistic flow figure of say 165 cfm x .43 for a lower lift we get 70.95 bhp per cylinder x 4 = 283.8 bhp. Which is roughly where we are with the 2 litre engine at the moment.

 

Flowbenches do not tell you everything but are a good tool to give you an indication that you are heading in the right direction when you modify a head. The fact that you get a certain amount of cfm from a head doesn't guarantee a power figure. It can be more or less. If all the other components have been selected properly, cams, induction and exhaust, you can get more power than the flowbench indicates.

 

Some people manage perfectly well without a flowbench. The best MGB head I ever saw were done by a couple of old fellas in a shed in Birmingham. They had never seen a flowbench but the head was spot on, both on the flowbench and the dyno.

 

The idea of flowbenches is not a new one. I was told that Harry Ricardo was flow testing cylinder head ports in the 1920's. By using a known quantity of water in a tank connected to the port he could see how much time it would take the tank to empty using a stopwatch. The better the flow the least time it would take to empty the tank.

 

In fact I like to think of a flowbench as a tool to measure restrictions rather than outright flow. Which is pretty much what old Harry was doing 90 years ago.

 

The same way you get BS figure quoted from dynos you can get BS figures quoted from flowbenches. I was given some heads to test by someone once that had been ported by someone who had a flowbench. The figure quoted was 126cm. When tested the heads flowed only 105 cfm. The guy porting the head was relying on nobody testing it afterwards. I've heard of people having flowbenches in the corner of the workshop because, I quote, "I don't use it but it makes the punter think we know what we are doing".

 

Jonathan

 

I have spoken to a few people and basically there is no real money in publishing a book. The advice Dave Walker from Emerald gave me is to by all means write the articles and to put the articles on my website. The website is always painfully out of date and I should be putting more effort into it.

 

"I'd encourage you to put them on the web with free access, good proofreading and lots of pictures." It's a good idea, but it takes time and I do have a habit of procrastinating. I have new products to go on the website and even the photos for the old products like the silencers and throttle bodies are out of date. The racing successes and photo galleries need updating, etc.

 

I suppose for the last two years I have been treading water trying to decide in which direction to swim. I thought I had lost interest in engines. The truth is that I have lost interest in road engines in the 210-270 bhp that more or less anyone can build. Racing is the ultimate test, so that's what I will concentrate on for a while. Development and design is what interests me not being a fitter of other people's parts to a known specification. Engine tuning is about going forward and trying new things, not nailing the same old stuff together. Otherwise your mind atrophies.

 

Thanks for the feedback guys. Especially Tony for his honesty and frankness. I'm thinking of changing my signature from AMMO to DOT.

 

 

[Klunk]

Thanks for the explanation and example. Much clearer than the info I've been reading.

 

Can I just check where the 0.43 comes from? Is it 0.43" (10.9mm) of cam lift?

 

Giles

 

Edited by - Klunk on 25 Feb 2013 09:28:18

[Garry7]

Ammo, please keep writing this stuff - it has got me interested in engines again, used to meddle years ago pre company cars, but since buildng my 7 last year I think I might be leaning towards an engine as a next project. I bit the bullet and paid the premium for a Duratec over a Sigma thinking that the power (175) would be plenty for me. Whilst it is great fun I can see the time fast approaching when I will want some more.

Keep it up mate, you are waking up a lot of people with this - although thankfully I can still get a whole nights sleep (at the moment!!) 😬

[myothercarsa2cv]

Ammo, thanks for the above - really interesting and I do like a bit of maths to get stuck in to! I applied this to the 2CV:

 

Inlet valve = 40mm, area = ~1.9 sq in

Assuming ideal flow of 50cfm per sq in, the head could flow 97 cfm.

Multiply that by .43 gets a potential power figure of 41 bhp per cylinder, or 82 bhp for the engine. Which is quite close to what the guys in Belgium with the forged cranks, twin spark fuel injection engines are getting.

 

If I work backwards, with my engine power being 15.5 bhp per cylinder, that equates to a mere 36 cfm flowing through the heads currently, or 19 cfm per sq in - that sounds ridiculously low and a long way off. However, the route to the cylinders is tortuous going through an airbox, carb, along some very long and curvy inlets and through the cylinder head - this would no doubt be improved with DTH TBs and some porting! However, if I can get the flow up to only 50 cfm, I could potentially see over 40 bhp which would be fun!

 

What I'm not sure I understand though is why the potential power per cylinder isn't linked to capacity in any way? Is it because the inlet valves tend to be matched to capacity?

 

Also, you say that the size of the inlet valve gives a good idea of potential power - does the exhaust valve not have to flow equally well? Obviously the potential can only be realised if all the other factors are taken in to consideration - for example, even if I could get the heads to flow 50% more, if the cam isn't up to it, the improvement won't be noticed?

 

I would love to know how to take that target flow rate and figure out exactly what you would need in terms of duration and other stuff to achieve it!

 

Sorry for the newbie questions

[Klunk]

John,

 

Capacity and valve area are linked critically in terms of air speed. The bigger the capacity, the faster the air will be drawn in for a given rpm/valve area. From what I've read (and I hope it's not complete rubbish!) the maximum velocity air can travel, and still be of use in terms of power, is 0.6 x speed of sound. With a large capacity piston you will achieve this at lower rpm than small capacity one for a fixed valve area. I'm trying to find the site I read it on.

 

The exhaust valve is normally a proportion of the inlet diameter e.g 0.7 x inlet. Doesnt have to be as large due to the temperature (and hence speed) of the gases. Sometimes you can increase the inlet and decrease the exhaust

 

All very complicated but fascinating at the same time. That could say something about me though 😬

 

There is so much stuff on the net it's trying to work out what's valid and what's not. The "hipermath" website is interesting. Apologies for not linking but can't do it easily on this phone.

 

Giles

 

 

 

 

Edited by - Klunk on 25 Feb 2013 13:49:05

[myothercarsa2cv]

Thanks for the reference, Giles. Just been to the hipermath website and just wasted loads of time getting sums wrong!!! Trying to figure out the max rpm of a 2cv with a club race cam, but I need max lift and I can only find lift at TDC. Ah well

[AMMO]

Giles

 

The figure of .43 is not linked to lift but the calculation Superflow use to predict bhp from airflow in cfm at 10" test pressure. Theoretically the engine can make .43 of a horsepower for every cfm.

 

Garry7, I think you did the right thing in getting a Duratec. I'm sure that the Sigma is a lovely engine but the capacity limits torque and power. If you are happy with the power the Sigma puts out or its tuning potential that's fine, but the Duratec offers so much more scope. I have some engine customers abroad who have fitted my kits of parts to the 175 bhp engine that converted them to 280 bhp engines for the track. These are clever race engine builders in Italy and Prague. I have visited them and have seen the quality of their porting. They all made the predicted 280 bhp +. How many other engines out there that produce 145 bhp in a road car can be relatively easily uprated to almost double their power in N/A form? Starting from Caterham's bottom of the range 175 bhp engine we are talking over 100 bhp more. It is an amazing engine and that's pretty much why I have been a big fan of the Duratec since I first clapped eyes on one in bits in 2001.

 

Giles, to expand on what you have said I can give a practical example. I flow bench tested two heads years ago. A stock 2 litre Zetec and a Suzuki GSXR 750 race head. If I remember correctly they had the same valve sizes and flowed approximately the same. They both have the potential to make the same power but at different rpm and with different torque. Let's say around 160 bhp. The Zetec will make maximum power at around 6,500-7,000 rpm and the Suzuki will make it at 15,000 rpm but with a lot less torque. The head pretty much dictates the power, the capacity dictates the rpm and torque.

 

As for the exhaust valve sizes, these are usually in the region of 85% of the inlet size. The Duratec has 35mm inlets and 30mm exhausts. The figure of 85% seems to work pretty well. Flow for the exhaust valve in comparison to the inlet can be around 70%. There are differing opinions to what you actually need. Some say as little as 65%, others swear that you need 80%. Somewhere around 70% seems to work. The exhaust system, cam and cam timing, induction all have an effect on how the exhaust port behaves. Some say having a smaller port with a bigger, slightly mismatched exhaust has an anti-reversion effect. Some say you need a bigger port with no mismatch. You could test all the variables until the cows come home.

 

2CV. The tortuous intake, carb and air cleaner will be restrictive. Every time you make the air change direction you lose some flow. The Belgian guys run a pretty straight shot with a tuned length on their 2CV. That will be worth quite a bit over standard. When we were racing air cooled two valve twins the best we saw was 95 bhp per litre. I stopped development on 2 valvers in 1993 when we started racing a four valve engine. Haven't looked back since. 2 valve engines don't interest me much. If you could get around 55 bhp out of your 2 CV you would be doing well in my opinion.

 

I played around with a computer program that came with a book from the US that was geared for 2 valve V8's. This was a long time ago. The program was in DOS. I still have the book and 3.5" floppy disc somewhere. As I was involved with 2 valve twins it suited me. You could jiggle cam timing and induction and exhaust lengths. It was sort of fun but the figures it gave were not really credible. The conclusion I came to was that there is no substitute for actually building the engine and sticking it on the dyno, messing around with cam timing, induction and exhaust lengths to see what the engine actually does.

 

For your engine I personally wouldn't set my aims too high. Even just another 30 or 40% increase in power would be nice to have and would be more affordable. If you want to chase the revs you are going to need a crank. I would look at what can be done with the stock crank first. Pretty much what I have done with the Duratecs I have built. I've stuck three different types of steel cranks in engines of varying capacities that were over 280 bhp. They worked sort of OK. The only one I would trust is the one I had designed and made for the 2.2 litre. The 2 litre is the only one I haven't run with a steel crank. To safely yield the benefits of the higher rpm and to be able to sleep at night that is the way to go. If you can't afford a crank don't rev it. That's what we have done with the stock crank that is limited to 8,500 rpm and it is lasting very well. Four seasons of racing in one case and 16,000 km of track miles in another. The 16,000 km engine went pop recently. It made a terrible mess when it dropped a valve. I put it down to the daftness of the customer who didn't have the engine re-built when he should have done. Now he needs a new block, head and loads of work. If he had refreshed the engine at a more reasonable mileage he would have had a much smaller bill for new valves, springs, shells, rings etc. Nobody should run a race engine for 16,000 km. If nothing else it has proved how durable the engines can be.

 

For any engine to work all the components have to work in unison. Rather than grab a bit from here and a bit from there, look at the engine as a whole and what you want it to do. It has to be designed as a package from the start. My personal opinion is that you shouldn't take little stabs at it. Life is too short. Decide what you want to do and do it. My customers wanted to do a bit this year and a bit next year and a bit the year after that. Why? Just get on with it. Borrow the money if you have to, use a credit card, take out a loan. I never asked a customer to do something I hadn't done myself. Some went away, saved up the money and came back with the dosh two years later. Some just got the credit card out and paid that off a bit at a time. As far as I know for the married ones this never actually ended up in divorce, but in some cases it might have been a contributory factor.

 

 

[Klunk]

Thanks for that - just a happy coincidence that 0.43 is the same as a zetec fast road cam lift then! 😬. Interesting to see the comparison between the 2 engines as well - it illustrates the point I was trying to make much more clearly.

 

The computer program wasn't Desktop Dyno was it? My engine guy came to the same conclusion - fun but ultimately pointless.

 

Your last point illustrates one of the problems/frustrations of the engine builder I guess - the client and their aspirations - "I want a roadcar with 300bhp, loads of low down torque, and it must be indestructable. Also, it must be quiet when I'm cruising and return 40mpg. Oh... and my budget's £3k". 😔 😬

 

Regards,

 

Giles

 

 

 

[Neil66]

Quoting AMMO: 

... As far as I know for the married ones this never actually ended up in divorce, but in some cases it might have been a contributory factor.

 

Great stuff Ammo - LMAO!!!!

[myothercarsa2cv]

😬 SWMBO is patient, but whether I'd want to test her limits? Who knows... Maybe when I'm a bit more flush In the meantime, I shall play with some maths and plan plan plan... And maybe do a bit of secretive saving 😶‍🌫️

[Tony Whitley]

Make sure Ammo doesn't undo your cunning financial plans at the last moment as he did with a "prominent former member of the club", leading to discovery by SWMBO (fortunately of only the final payment, not the down payment). PFMOTC allegedly ended up grounded until he'd redecorated the whole house as he'd previously used the excuse of poverty to refuse to pay for a decorator

[myothercarsa2cv]

Haha! 😬

 

Well, I've now spent far too much time on the hipermath website, and I'm not sure I trust their calculations. Apparently the ideal TB for a 2CV is 26mm. Thinking, well, it's a small engine, I thought I'd check the 1.6K, and it produced 43mm, and the Duratec, for which it recommended 48mm, all for optimal airflow at 6500rpm (increasing this to 7000 didn't make a huge difference. So either my maths is wrong, or the equation they give is wrong... Back to school for me!

 

Edited to correct the above as I'd forgotten to update the number of cylinders...

 

And interestingly... Giles, I reread you post and saw that the speed of airflow was only 0.6 times the speed of sound as a practical max. I plugged this in to the formula (instead of using the speed of sound as it suggested) and it produced much more reasonable results, with 33mm for the 2CV, 55mm for the K, and 62mm for the Duratec.

 

Further edit - but now I'm not sure how the number of cylinders affects it, as on 4 and 2 cylinder engines, only one cylinder is sucking at a time... Headache time And obviously all this assumes the cylinder head is flowing nicely!

 

Edited by - myothercarsa2cv on 26 Feb 2013 13:32:55

[Klunk]

I think I questioned some of the maths too. Wallace Racing have some interesting formulae as well. Trouble is depending on what you look at you get different theoretical BHPs etc. As Ammo has said, theory is one thing but reality is often completely different. The effect of thermodynamics on the "simple air pump" makes it anything but simple. Apparently the lotus engine software is very good but I dare say it might cost quite a bit of money .

 

Giles

 

 

Edited by - Klunk on 26 Feb 2013 18:47:52

[Dr Slotter]

There is a Freeware version of LES (it just does single cylinders) if you fancy having a play.

[Klunk]

Good spot . Downloaded and reading the manual. I may be sometime.......

[Birkin S3 ZA.]

Quoting myothercarsa2cv: 

Haha! 😬

 

Well, I've now spent far too much time on the hipermath website, and I'm not sure I trust their calculations. Apparently the ideal TB for a 2CV is 26mm. Thinking, well, it's a small engine, I thought I'd check the 1.6K, and it produced 43mm, and the Duratec, for which it recommended 48mm, all for optimal airflow at 6500rpm (increasing this to 7000 didn't make a huge difference. So either my maths is wrong, or the equation they give is wrong... Back to school for me!

 

Edited to correct the above as I'd forgotten to update the number of cylinders...

 

And interestingly... Giles, I reread you post and saw that the speed of airflow was only 0.6 times the speed of sound as a practical max. I plugged this in to the formula (instead of using the speed of sound as it suggested) and it produced much more reasonable results, with 33mm for the 2CV, 55mm for the K, and 62mm for the Duratec.

 

Further edit - but now I'm not sure how the number of cylinders affects it, as on 4 and 2 cylinder engines, only one cylinder is sucking at a time... Headache time And obviously all this assumes the cylinder head is flowing nicely!

 

Edited by - myothercarsa2cv on 26 Feb 2013 13:32:55

 

Just fit a BMW air cooled boxer motor no one will know or catch you to find out 😬 😬

[myothercarsa2cv]

Come on now, that's cheating! They're also too heavy and it under steers bad enough as it is...

[AMMO]

Giles

 

The book was Desktop Dynos. Computer engine simulation has probably moved on since then. I have a friend that works at Lotus that reckons that their software can even predict the sound the engine is going to make. Personally I'd rather build the engine as I said before.

 

"I want a roadcar with 300bhp, loads of low down torque, and it must be indestructable. Also, it must be quiet when I'm cruising and return 40mpg. Oh... and my budget's £3k". You forgot "and it has to pass the MOT"

 

Something you use to inflate bicycle tyres is a "simple air pump". Internal combustion engines are much more complex. For me the complexity is to do with component selection and all the variables you can have. Induction lengths and exhaust tuned lengths, cams and cam timing, valve sizes, airflow, throttle body sizes. A proper development program would cost lots of money having components made and take weeks of dyno testing. I did a three day stint at Emerald that cost me around £1,500.00 at mate's rates as it was all I could afford. If I was rich I would gladly throw 20K at it to find useful information out. As I have built a lot of different engines with different bores and strokes, valve sizes, cams, exhausts etc. I can take an educated guess at what is likely to happen.

 

The prominent former member of the club / decorator guy Tony mentioned asked me to build him an engine that made between 260 and 270 bhp. It made 265 bhp on the dyno with another 5 bhp to come once it had bedded in. Those sort of engines you can churn out all day as we know more or less what there is to know about them. But even those haven't really been fine tuned. Another guy asked me to build him a 280 bhp engine. It made 265bhp too. When we looked at the exhaust he had bolted to it the header lengths were all over the place. Cylinder no.1 was 36" long, no. 2 31", no.3 37" and no. 4 31". To avoid getting the "you said it was going to make x power" conversation with the customer, especially for the 300 bhp + engines, I decided to have my own exhaust made. Cost a fortune with little profit in it but it had to be done. But even that was based on an educated guess based on experience. "Make me headers to these dimensions" and it worked. Had we had a budget we would have tried different things. At the end of the day it is good enough, but who knows if it could have been made better.

 

That is the point of it all. To do as good as or a better job than the next guy. People who go racing have a character flaw. They want to prove they are better than the next guy. We did a lot of winning in the old days. It is addictive and becomes an obsession.

 

A Duratec that turns 9,500 rpm reliably lap after lap is an unknown to me and that's why it is more interesting. It is also an obsession. For that engine which unfortunately I don't get to build until next winter I am going to look at every single aspect that will give me an edge. I probably won't be able to charge the customer for every hour that goes into it, but from a personal satisfaction point of view I am itching to do it and have been for a few years now. The 2 litre Duratec is unfinished business. As I have said before I was knocking out engines with 75 bhp per cylinder almost twenty years ago. If we had the budget the engine would have been much further down the line by now.

 

2 CV, regarding throttle bodies and the software prediction of 62mm. I have tried 60mm throttle bodies on a 580cc Ducati single in 1998. The stock body was 50mm which I had taper bored to 54mm. At the time Ducati offered 60mm throttle bodies as part of a race kit for the World Superbike V Twin. We found two guys racing the singles that were willing to fork out the 2.5K required to buy the big bodies. End result was that they made the same power (75bhp at the rear wheel, up from 63.5bhp) as the 54mm but that the 54mm held onto the power for another 500 rpm. I'm glad someone else paid for the throttle bodies!

 

I also know someone who has tried 60mm bodies on a Duratec and says that they didn't work for him. He now uses 53mm ones, I use 54mm. So we pretty much came to the same conclusion. He also does motorcycles. His 600cc four cylinder engines run 40mm bodies. I think if you have your feet in two camps, cars and motorcycles, you tend to favour the larger bodies. Here the flow bench can be your friend as it seems to me that you really don't want to put something on the engine that restricts the flow. There is also no point it putting something on that is too big though.

 

What we found with 2 valve motorcycles and carburettors years ago is that the carb works OK at around 95% of the valve size. So the Guzzi we raced successfully and won championships with had 44mm inlet valve and a 40mm Dellorto that I bored out to 41.5mm. For your engine 95% of your 40m valve size would be a 38mm. My guess is that in real life this is going to be a bit too big. For the road I would use something like a 34mm to maximum 36mm. That's for a slide carb. For a CV carb with a butterfly you could possibly go bigger. You could probably pick up some CV carbs off eBay quite cheap. Unblocking the induction on your engine would probably give you a big gain on it's own. If you go too big the engine probably won't pull the skin off a rice pudding at low rpm. Again it is looking at the engine as a whole and getting everything to work together. I have a funny urge to go out and buy a 2CV. Your project has got me curious. If you do get an engine in bits at some point I wouldn't mind having a look inside.

 

Going back to looking at pretend engines on a computer, it's basically the same as looking at women on the internet. Not the same as the real thing. Which reminds me, I have an appointment with a very pretty brunette for lunch.

[Klunk]

Morning Ammo,

 

Totally agree regarding the software - I'd much rather be playing with the real thing. Having spent a couple of hours on the software last night it is very impressive, but man is it complicated when you get into detail. It doesn't get the engineering juices flowing in the same way either - probably one for the xbox generation. That said, I'm going to persist with the model just to see if it throws up anything interesting.

 

Enjoy your lunch

 

Giles

 

Edited by - Klunk on 27 Feb 2013 09:22:50

[myothercarsa2cv]

Ammo, I've got an old block sitting around doing nothing that I pulled apart to make sure I was pulling the right bits off my own engine. It's probably unusable now (no doubt most of it's a bit rusty, crankcase will be perfect though), but if there's a GONADS going your way, you're welcome to it. I also had a go at porting the heads on it with a dremel to practice in prep for my own (so they're probably ruined too, hey I was young ), but never got round to actually fitting them to see if they worked; when you drive your car every day there's just no time to be swapping heads like a mad man - especially when the wings have to come off to get to them

 

Thanks for the advice on the TBs And all the advice in general - very much appreciated, and I hope one day I'll get round to putting it in action!

[MikeMolloy]

Quoting AMMO: 

A Duratec that turns 9,500 rpm

 

What do you think of the SBD 2 litre Duratec here?

Claim is 307bhp and 200 lb ft, >9500rpm (with peak power about 8800), 13.2mm inlet cam lift.

[Klunk]

Without wishing to pre-empt Ammo's response, and in light of the fact he's currently entertaining a pretty brunette , he posted this earlier on in the thread.

 

The Ford Duratec is pretty much spot on with the critical dimensions. Anything you do is to improve what is already there. It is possible to get the intake up to 178 cfm @ 10" with the stock valve and without resorting to ports that are that much bigger. The heads with bigger ports give worse flow figures at low and mid lifts. They make big numbers at lifts we don't have cams for at around 15 or 16mm. As realistically you are not going to use cams like this best it is best to stick to sensible dimensions for the port, save time and money and keep the gas velocity high as ultimately this is what will help fill your cylinder and help volumetric efficiency.

 

Reversing Ammo's calculations 307bhp equates to 178cfm. Clearly, if you can get 300bhp from a stock valve that would be preferable.

 

Giles

 

Edited by - Klunk on 27 Feb 2013 17:00:46

[AMMO]

Good luck with the project 2CV. Thanks for the offer of sending over your old engine. I might take you up on it at some point.

 

Fred

 

SBD are to be complimented on their results. They are a much bigger and more successful concern than Raceco ever was or ever will be. They have more resources at their disposal to do this sort of work. Funnily enough when Raceco was at its height in the mid 90s and employed 5 staff we were also based in Surbiton. Just up the road from SBD. Now Raceco is just one person. Me.

 

A couple of things I would like to point out though. What SBD have done is their engine in their own way. Their design philosophy is completely different to mine. They have bigger ports and bigger valves. Almost the opposite of what I want to do.

 

I want to do my engine differently, using stock valve sizes and smaller ports to achieve similar results at a lower, more affordable price. The target power is going to be 295 bhp which I am confident can be done. People that know me know that I tend to be conservative with my numbers. If we can break 300 bhp that would be a bonus.

 

The big valve heads I have done in the past cost around £2,500. I can hand port a head with standard valves for around £800.00. That is a big saving. The money saved can be put towards a crank that will hopefully make the engine bullet proof. I'm thinking more on the lines of an endurance race engine. In the old days we would strip and check our engines every race. I have been told that BTCC engines last only 800 kilometers before they go off and lose 20 bhp. Customers nowadays expect to race a whole year before coming back for a refresh. They also want the engine to be making as much power at the end of the season as it did at the beginning.

 

Experience has taught me that there is more than one way to skin a cat. In my first year of racing the Moto Guzzi in 1986 I built an engine that we tested at Leon Moss' Ledar dyno. It ran 40mm carbs with long bellmouths. We had straight pipes made and chopped them off an inch at a time until we found maximum power. When we went an inch too far and lost power we welded an inch back on. In those days there was no noise testing, you could run with no silencers and you could make as much racket as you wanted. The bike was very loud and would hurt your ears. Did sound nice from the pit wall when it was on song though.

 

The next race was Snetterton. In the paddock was another Guzzi of a fellow competitor. He turned up with short bellmouths and a longer exhaust system, also just a straight pipe, no silencers. I was pretty confident he had got it wrong. In the race the bikes were neck and neck. On the back straight, which is the final proving ground as far as I'm concerned, the bikes were equal. Nothing at all in it. Neither would stomp away from the other. It taught me that there is more than one way to get the same or similar result.

 

Ten years and ten race seasons later, after a race at Snetterton, Geoff Baines who was racing a Ducati came up to me and said "Your bike is a rocket, Paul (Lewis) came up alongside me, waved, popped a wheelie and pulled away from me on one wheel". Still make me smile to this day. We won the championship that year, Geoff came second.

 

I want to do my Duratec engine my way, using my own intellect. Copying other people or using other people's parts doesn't interest me one little bit. Regarding my engine design philosophy I do have some track record. Winning championships with 2 and 4 valve Guzzis and helping others win races and championships with bikes and cars. What I am doing is using tried and tested ideas behind tuning the Moto Guzzi Daytona and the Ducati Supermono and apply them to the Duratec.

 

The Supermono is an interesting case because it won the singles race at Daytona. If there ever was a speed circuit that is it. The long banking really sorts out the men from the boys. The bike also came third at Daytona in the BEARS (British, European and American Race Series) that was open to twins and triples. It also came second in the Isle of Man. The difference between the Ducati and the Guzzi and the Duratec is that years on we have a cylinder head with standard valves and a few mods that flows more than both the Guzzi and the Ducati did. Thanks to Ford. They did a great job. The head is great out of the box.

 

Of course I secretly hope that my Duratec engine will do well when it is finally built how I want and it finally gets tested. I am also (reluctantly) willing to accept failure if it doesn't work. As I hate failure I will do everything I can to make sure that doesn't happen.

 

Edited by - AMMO on 28 Feb 2013 08:50:43