Duratec 2 litre. Why we need more revs.

[AMMO]

Some may have read about my quest for more power and more rpm from the 2 litre Duratec. I've been looking at flowbench figures, ports, exhaust system tests and all sorts of other things over the last week or so.

 

I think the way to actually show why I have this obsession with rpm is the show you a graph from various 2 litre engines I have built. here

 

The 220 bhp and 260 bhp spec engines were fitted to my own car. With the 220 bhp engine I was hitting the rev limiter through the gears all the time. With the 260 engine less so. 8,500 rpm with the stock crank on both the 260 and 280 bhp engines is pretty reliable. Not had any bottom end problems at these rpm.

 

The 280 bhp race engine was built five years ago. If you look at the green power curve you can see that it hits 280 bhp at 8,500 but that another 280 rpm give another 6 bhp. You can tell from the power and torque curves that it still wants to go up. Taking the engine up to 9,500 should see it go over 290 bhp. With more modifications over 300 bhp should be possible on stock size valves.

 

The reason for stock valves is that it would save quite a bit of money over fitting a big valve head. Everyone is on a budget and adding lots of money for a big valve head is money not well spent if you can get the power by other means. If you can do an easy and affordable porting job and bolt on the proven ancillaries for good performance then that is the way to go in my opinion.

 

I have tested a big valve head on the flowbench with an 87.5mm bore adapter and with an 89mm bore adapter, the two piston sizes I regularly used. The increase in flow that the big valve head offers is somewhat negated by the shrouding of the 87.5mm bore. In other words the big valve head works well in the bigger 89mm bore engine rather than the stock 87.5mm bore. The big valve head comes into its own on bigger capacity engines with bigger bores.

 

The 35mm valve is about right for a 2 litre, the 36.5mm valve I designed works well on my 2.2 and larger engines.

 

I did some work on the Nisan Touring Car heads in the 90s. Thes Nissans made 312/314 bhp with 35mm inlets. I've heard that once the 8,500 rpm rev limit was removed and these engines went into private hands they made 324-325 bhp. I am friends with the people involved with this engine. When I asked what was it that made them make more power, the answer was "everything". I wouldn't say the budget was unlimited but big figures, running into millions were being bandied about at the time. The engines were made by IES, Judd and AER. Prices were between £53,000 and £75,000 + VAT each. A friend who was heavily involved in the development said they spent around a month working on just the bellmouths. They probably spent similar amounts of time on exhausts and various other parts.

 

Port sizes is another thing I have been looking at a lot. My ports are not overly large and yet they flow really well. I found some flowbench figures for ports of various sizes and the larger ports flow less. It seem hard to believe but that's the way it is. Actually what happens is that a port that is too big the low lift figures suffer and the high lift figures go up. With a big port the flow doesn't stop until 16mm lift. As we don't lift the valves to these figures there is no point in doing this, especially if the low and mid lift figures suffer.

 

Basically the port has to be in proportion with the valve. If the port is out of proportion the flow and gas velocity will suffer. If you are hitting the rev limiter at 8,500 with the power still rising I can tell for a fact you that your ports are not a problem.

 

I seem to have new enthusiasm for these things. A two year break without building any customer engines was probably what I needed. Raceco was started by me in 1986 to go racing and to develop and build race engines. I'm not interested in building dozens of 210 -260 bhp engines, something that I was doing all the time. I want to do development which is after all my forte and has bought me success in the past.

 

I've done lots of varied and successful projects. Stuff that has won races and championships. Recently I have been in a rut. To build the same spec. engines over and over again is no fun and a waste of my abilities, especially when you are competing on price and not making any money. I want to do new stuff all the time, things that tax my brain. Bolting engines together to a known spec makes you a fitter not an engine tuner.

 

The frustrating thing is that all of the development work would have been done and dusted years ago had a budget been available. Another thing I realised is that building engines that go well on the dyno is one thing but the real buzz is seeing the car or bike with my work going around the track. I have two 280 bhp spec. race engines in two cars this year in the same race series. One in a Westfield and one in a Caterham. I haven't been to a race track to watch a race in a ages.

 

Time I jumped in my Caterham and went to have a look.

 

Hope you didn't nod off reading this.

 

Edited to correct a typo. Thanks Mankee!

 

Edited by - Ammo on 7 Feb 2013 08:28:50

[Mankee]

Morning Ammo. Nothing like a bit of light reading for a Monday morning! Much more interesting than my day's subject of rock mechanics...

 

Is there a typo with the bhp numbers? As in, the Nissan engines jumped up to 324-325bhp when they were derestricted and sold?

[Jonathan Kay]

Nod off? It's fascinating: please keep it coming.

 

Jonathan

[AMMO]

Mankee! Just the man. I wanted to talk to you about a couple of things. Pop over for a cuppa or a beer soon?

 

I think whole Nissan touring cars were sold off at some point and ended up being raced privately. What I have heard is that they made more power when they had the rpm limit raised and had some additional work done. Quite a bit of time was spent on the dyno developing new exhaust systems.

[Eugene]

I'm a fan of higher revving, smaller capacity engines, but its knowing what needs 'changing' to get the higher revs???

 

I'm not going to change to a Duratec, as I really am very happy with my Zetec and the power it presently produces, but if some time in the future I were to look to increase power through more revs, what would be the things to look at with the Zetec?

 

Now, there's a question that has no simple answer!

 

😬 😬 😬

[Mankee]

Quoting AMMO: 

Mankee! Just the man. I wanted to talk to you about a couple of things. Pop over for a cuppa or a beer soon?

Sure thing, Ammo! I'll give you a buzz hopefully later on in the week when I can get away from the computer for a bit, possibly one evening.

[AMMO]

Hi Eugene.

 

Zetecs are nice engines. As for what stops the engine revving I'd be looking at cylinder head, cams, induction and exhaust system. The willingness to rev in a Duratec is due to the exceptional flow capabilities of the head in standard and modified form for starters. Once you start bolting on the right bits the engine really flies. With the Zetec you have limitations as the engine is undersquare, the bore is smaller than the stroke, the valve and port sizes are smaller so you will never achieve the figures of a Duratec.

 

Be careful of chasing power you don't need. I ended up with 260bhp in my Duratec and hardly use it. I'm de-tuning it to make it more suitable for the road. Anything from 190 bhp up is going to be fun. A tractable 230 bhp in a road Zetec is probably the top figure I would be aiming at.

 

I was speaking to Geoff Wilson at HWR as one of his customers ordered some bits from me to put on his engine. We got chatting and both agreed that too much power on a road car would be a hindrance in a light vehicle. Racing and track use is another matter, you need all the power you can reliably get if you want to go past people on the back straight at Snetterton.

 

Last night I fell asleep early and woke up at 1 am. This time I was working out BMEP figures for the 2 litre. It is generally accepted that around 230 lb brake mean effective pressure is in the right ball park for a race engine. When we got 185 ft.lb. of torque on the dyno Dave Walker commented that I wouldn't get much more than that from a 2 litre. So that got me curious. The BMEP figure for my engine is 227 lbs. so pretty much there or there abouts. You could get more but it would cost more money in development.

 

What I am thinking of is an engine that isn't difficult to port and doesn't need big valves but has components that work in conjunction with the head. I have sold kits of my parts to professional engine builders abroad who have got exactly the same power outputs as the engines I have built. What I am thinking is kits that contain everything you need to make a 280 bhp engine with a stock crank or a (I'm guessing here) a 295 bhp engine with a steel Raceco crank. I even thought of modifying the stock crank but at the end of the day I don't think it is worth spending any money on. Better to do the job right.

 

Also had a half hour conversation with the man that is going to design the new crank. Lots of little details and intricacies to discuss. Although the 88mm crank will form the basis of the 2 litre one it needs a complete re-design as it is doing a different job, different journal sizes, rpm, etc. When I sent the drawing of the 88mm crank to crank manufacturer they called me up to see if they could make some changes to the drawing to make it easier to machine. I told them that I had just paid £800.00 + VAT to someone to design it I didn't want it changed in any way. As a lot of the Duratec parts I have made have been copied I have not shown photos of the 88mm crank to anyone. Some of the customers who have them in their engines haven't even seen it.

 

I have decided to concentrate on the 2 litre from now on. I've done almost 2.5 litre engines and everything in between. Big engines are OK for rally cars but have no real place in a Seven in my opinion. Unless you like wheel spinning all the time Also the 2.3 engines are no longer available and have been replaced by a 2.5 with a 100 mm stroke. Not exactly a race engine. More like a tractor. Not interesting to me. The 2 litres are also readily available second hand so it makes a lot more sense to cater for these.

 

Looking forward to these new developments. I have been treading water for the last couple of years. Not building engines for a living has taken a lot of stress from me and allowed me to do other things. I still enjoy the development work though.

 

I wonder about airing my thoughts in public and whether people find these things interesting or not or just the ramblings of an obsessed bloke. From a selfish point of view writing it down helps me put my thoughts in order though.

 

 

[Klunk]

Fascinating stuff Ammo - please ramble away. If I could wind the clock back I would love to done the kind of development work you are talking about. I have many similar conversations with the guy who builds my engines. He shares many of the same thoughts you do, including the difficult and often frustrating nature of the business .

 

Regards,

 

Giles

[Damdy-Cash]

Quoting AMMO: 

I wonder about airing my thoughts in public and whether people find these things interesting or not or just the ramblings of an obsessed bloke. From a selfish point of view writing it down helps me put my thoughts in order though.

 

not at all, very interesting stuff!! Keep going please!!

 

Cheers Volker

[David Brown]

I have found this fascinating. Having ported the head on my 1.6k myself, I have often wondered whether a rough port giving more turbulence and better mixing was better than a highly polished one with better flow but poorer mixing.

 

David

[Slipper man]

Ammo - they are the ramblings of an obsessed block. And absolutely fascinating to the types of anoraks (like me!) who read BlatChat. Keep the thoughts coming!

[Johnty Lyons]

Bloody brilliant Ammo keep it coming

[AndrewGP]

Quoting Johnty Lyons: 

Bloody brilliant Ammo keep it coming

 

Absolutely

[Dave Allen]

Ammo it's pure gold.

[Jerry Auton]

[Pete - W.Sussex]

Keep going Ammo - for a complete Numpty like me it is fascinating.

[AMMO]

Thanks for the positive comments. Keep them coming! 😬 Everyone likes a pat on the back now and again.

 

I just read some of this and realised that there was a typo in a post that Mankee spotted. The reason I want to meet up with Mankee is that I am thinking of writing some articles and possibly a book and need someone to proof read my scribblings.

 

Thinking of an anecdote and photo rich technical book. The sort of thing I like to talk about with friends but with flowbench figures and dyno graphs. Something that is an interesting read that also imparts tuning knowledge. I've been asked to write books on two occasions. The first was on Moto Guzzis around twenty years ago. I actually took an advance on this that I returned after a few months when I realised what a huge task it was and that I would be working for a pound an hour. The second was a tuning book on Duratecs very early on when I knew even less than I know now about the subject. Dave Walker put me forward for this. I again refused as the money was abysmal and the royalties not that great either. Thinking of self publishing perhaps. Maybe a toe in the water with some articles to start?

[Mankee]

Very quickly, I would just like to state that I was really hoping you were planning on publishing your work and findings. I'm very excited for you! Will catch up with you soon.

[tangomikeromeo]

Well Clarkson makes an income by simply collating his newspaper articles and publishing them in one handy volume every Christmas. Maybe a start could be a collection of your musings and follow the trains of thought as they come to you - I'd buy it.

 

(And please keep the insights coming - you explain the techincal to the interested layman well)

[myothercarsa2cv]

A book would be brilliant, especially if the theory is applicable to any engine! I'd be surprised if someone like Retro Ford Magazine didn't snap you up for a series of articles on tuning... Could be a good way to gain exposure and grow the R&D work you want to do, and maybe get paid to do it. Then, As TangoMike says - collate and publish!

[Z3MCJez]

AMMO - I've just commented on the other thread that you should write a book! If you want an interested beginner to read the articles and comment, then I'd love to help It depends on who you are writing for - if you're trying to make it accessible to people who don't know what goes on inside an engine but are interested, then I may be able to help with what is clear and understandable and what needs more (or less) explanation. If you're trying to educate people who already have a working knowledge, then your market is much smaller and I'll be no help whatsoever!

 

However, I would try and mix some of the technical developments with the stories of the implementation. It's knowing how things have turned out (and where things haven't worked in real life) that brings it all to life.

 

Jez

[Klunk]

Retro Ford Magazine? Pah! PPC please - C'mon Mankee, use your influence 😬

 

On a more serious note Ammo, why not take the approach Dave Vizard has taken. He has written some great anecdotal general magazine articles/books on the general principles involved in engine building which generates the interest. On the back of this he does lecture tours at which people have to pay to attend and sign what is effectively a 'gagging' order to protect the knowledge he divulges.

 

Giles

 

Edited by - Klunk on 7 Feb 2013 12:07:37

[myothercarsa2cv]

Not heard of PPC before... but the £999 challenge looks fun - is it still running?

[Klunk]

here John

 

Apologies Ammo for the hijack

 

 

 

Edited by - Klunk on 7 Feb 2013 13:39:31

[Tony Whitley]

Sorry Mankee, excellent mag it may be but writing for PPC is not much of a recommendation for a poofreader

 

Ammo: put me down for a (signed) copy, it'll go well with my 70s copy of Vizard's "Tuning the A-Series Engine" and Dave Walker's "Engine Management".