Flow developed cylinder heads, high performance engine building, big valves and other performance parts

Order and Enquiry Status

Please stop wasting my time and yours by emailing me for free advice on your engine problems or technical issues you want to discuss. I don't have the time to answer all the emails from people whose engines aren't working properly or who think they have some marvellous new engine theory I might want to get involved in and any such emails will just get deleted without a response.

Post your questions to the Pistonheads Engine and Technical forum and if I have time I'll try to answer them in public where the information can help others at the same time.

July 2011. Some nasty person has recently corrupted my site with a Trojan script tacked on to the end of this index page which will have installed itself onto the pc of anyone who read this page. Apologies to anyone whose system has been infected with this. I recommend MBAM to remove such nasties. Google it. I've removed the offending item and will keep an eye on it in future.

June 2008. I'm taking a sabbatical from engine and head work for the forseeable future to concentrate on other things such as doing the house up and writing that book on tuning I've been meaning to get round to, so no more enquiries for these please. I might come back to it in a year or two if I muster the enthusiasm again. I'll still be selling my valves, Catcams and other products though. I may, and it's a very small 'may', take on something so interesting or unusual I can't say no. Tempt me - but not until I've had a break for the summer, done some serious fishing and chilled out a bit.

I also must get round to updating this site and adding some pics and a better menu system.

I'll also be adding a 'for sale' page for various things I have in stock like completed race heads, valves, blocks and engine sundries.

Fuel saving gadgets

Or those meant to allow you to use unleaded fuel with no other modifications or add power to the engine. Before you buy any of this crap, which includes magnets, catalysts, air bleed devices, resistors sold on Ebay, tin pellets in a tube, turbochargers powered by a hair drier motor, strangely shaped vanes inserted into the air intake which supposedly add 'swirl' to the air, things you drop into the petrol tank and other snake oil have a read here. http://www.fuelsaving.info/index.htm. I've been looking at these products for years now and the vast majority of them are useless junk designed to do only one thing - make the seller money at your expense. Avoid at all costs. There's a very simple rule. If something was cheap and easy to fit and actually did anything useful with no unwanted downside the OE manufacturer would have put one in to start with.

Say NO to 0870

Most people can now get phone service which gives free calls to 01 and 02 numbers. However, most large organisations want you to call them on an 0870 or 0845 number which you get charged for and they make money on. If only you could call them on an 01 or 02 number but you can't find out what it is. Now you can. Go here..link

You can type in the company name and get their normal landline 01 and 02 numbers. No more charges for calling your bank, insurance company, Internet Service Provider helpline, even the Police numbers are listed.

I now distribute Catcams cams, vernier pulleys etc. All their products are listed on their website at http://www.catcams.co.uk I'll get a price list up when I have time but they're very competitive as regards other companies products. After unhappy experiences with other cam companies I find Catcams reliable to deal with, they have a good range of effective profiles and also let me design specials as needed which they then add to their range. I can advise on engine specific cam selection as part of head or engine build work.

Congratulations to Sean Richardson for what we believe is one of the most powerful 2 valve per cylinder 4 pot engines in the UK. A ZVH (CVH head on a 2 litre Zetec bottom end) Sean had about 220 bhp when he came to me for one of my UBV (ultra big valve) CVH heads. The first dyno runs put that up to 300 bhp on the same boost but the turbo was causing lag and there were other problems to correct.  The UBV head giving an extra 80 bhp though - which was nice. With a new roller bearing turbo and some induction and exhaust issues fixed it's just produced 428 bhp and 404 ft lbs at 28 psi boost on Engine Advantages rolling road. http://www.passionford.com/forum/viewtopic.php?t=223162

A new article on choke sizes for DCOE type carbs has been added.

A new article on exhaust valve sizing has been added.

Contact Details - Email and snail mail addresses. Details for sending payments. Terms of business.

Company Services and Products - basically what I do and don't do. Please read before asking when you can bring your car to my 'workshop'. I don't work on cars!

Price Guidelines For Cylinder Head Work - should put you in the ballpark for heads that don't have their own tuning article yet.

NEW - Mi16 /S16 big inlet valves (36.5mm) now available. £140 per set of 8 plus £4 UK postage if required. Not suitable for the Gti6 engine which has 6mm valve stems. December 2006 - only 1 set left in stock. It might be worth making another batch but only with 5 or so orders up front.

Other valves available - 43.5mm and 45mm CVH, 44.5mm and 46mm Pinto, 43mm Peugeot 205 - all at £15 each plus £4 UK postage per set.

PRICES - The company is not VAT registered so any prices shown anywhere on this site are the total payable and therefore the same amount for export sales.

EMAILS - A fair proportion of emails are from people who say they have just read the tuning article relevant to their engine and then ask for prices and power outputs for head work or something else similar like cam choice that is already covered in detail in the article! One of the reasons for putting so much information in the articles was to save having to type it all out dozens of times a month for everyone who emails so if you fall at this first simple hurdle your email isn't going to get answered - sorry. Also please keep emails short. I spend dozens of hours a month trying to keep up with emails and long ones or ones asking for lots of information aren't going to get answered. I cannot enter into detailed correspondence with people wanting further discussion about the technical issues covered on my site. I answer questions in the uk.rec.cars newsgroups as time allows.

Customers - and my experiences of them. Which type are you?

History Page - Company history and championship wins


General tuning guide - an evaluation of the potential power increase from commonly used tuning mods. If your specific engine isn't covered below then have a read of this. Even if your engine is covered in a more specific article below it will be of benefit to read this first to get a more thorough initial understanding of tuning principles.

Tuning Turbo Engines

Ford Crossflow
Ford CVH
Ford Pinto
Peugeot TU3 1361cc 8 valve
Peugeot 205 8 valve
Peugeot M16


Power, Torque And Vehicle Dynamics

Engine Capacity and Compression Ratio - how to calculate them

Power and Torque 1- How they are related and the maths that explain them
Power and Torque 2 - Output levels for road and race engines, Volumetric Efficiency and improving engine design
Power and Torque 3 - How they are measured, engine dynamometers and rolling road dynos
Coastdown Losses - A real example of how these affect quoted "flywheel" power figures
How not to set up a car on the rollers - A case study of the dangers of relying on inaccurate flywheel power figures from rolling roads

Top Speed - how engine power and vehicle top speed are related. Using one to calculate the other. How speed affects fuel economy.

Lightening Flywheels - A brief exercise in rotational dynamics showing the effect on vehicle performance of lightweight components

Flywheel Balancing - tales from the trade

Computer Simulation of vehicle performance - the realistic alternative to dyno testing based on measured acceleration

Transmission Losses - the final piece of the jigsaw

Preparing For A Trip To A Rolling Road

Part 1 - Getting the car and engine ready for a power run
Part 2 - Choosing a rolling road and what work you should expect to be done when you get there

Engine Tuning

Evaluating an Engine's Power Potential

Article 1 - What is the main factor that determines an engine's power potential?
Article 2 - Other things to be considered, comparison of 2 and 4 valve per cylinder engines
Article 3 - Calculating the power potential of an engine in road and race tune
Article 4 - Evaluating the power potential of forced induction engines

Exhaust valves - what size to use

Carburettors, Fuel Injection, Air Filtration , Exhaust Systems and Calibration

Fuel supply - Guidelines to ensure adequate fuel supply for the target power output

Calibration - How fuel and ignition systems are calibrated. What "chip tuning" is meant to do.

Combustion Theory - basic combustion theory, using gas analyzers at a rolling road session

Choke sizes - for DCOE, Dellorto and other one choke per cylinder carb setups

Injector sizes - calculating the required fuel injector flow rate for a given target horsepower

Air Filtration - Calculating an engine's air demand and filter size requirement

Exhaust manifold sizing Choosing the correct exhaust manifold primary and secondary pipe diameters

Exhaust system sizing Choosing the correct exhaust system diameter for a given power output

Engine Maintenance

Tool Use Techniques - How to dismantle and reassemble properly. Dealing with stuck or corroded fastenings.

Compression Test - How to do one and what it shows about the health of the engine. Also explains "leak down" tests.

Fitting a new cam - How to fit and run one in properly

Running in a new engine

Diagnosing Engine Problems

Bronze valve guides - why you probably don't need them in your engine.

Unleaded Fuel

Part 1 - The mechanism of valve and seat erosion - why leaded fuel was developed.


SDS tech page - Here's an excellent site packed with accurate technical information on engine tuning, engine dynos and chassis dynos (rolling roads to us in the UK), combustion theory, turbo systems, fuel injection and other good stuff.

Jim Hearne's ZVH (zetec/cvh hybrid) site - everything you need to know about mating a cvh cylinder head and turbo system to a 2 litre Zetec bottom end. Loads of photo's (which I know my own site lacks but just wait till I get that digital camera). I did the ultra big valve head (45mm inlet valve) and some of the other engine work for Jim. Car should be mobile by about the end of July 2001 he tells me.
Sept 2001 - Well it's run in and boost upped to just 7psi so far and now he's grumbling it's too powerful and he can't put the power down :) The diary page of the car's history is here.
August 2002 - rolling road tested at 226 bhp at the wheels (at least 260bhp flywheel) on only 10 psi of boost which should give an indication of just how much air that 45mm valve cylinder head now flows.
Contact: contact@pumaracing.co.uk.