Has anyone thought about trying to redesign the R53 head to create better efficiency? Of course with better efficiency come more power. I would like to design the head with smaller valves and intake runners to increase velocity and increase efficiency of burn in the chamber.

This may include a completely new intake and exhaust design.

It must be something feasible though.

 

Do a search on 'jesus head' and 'thumper' - lots of different heads out there.

 

Your approach is misguided, smaller valves and runners do not efficiency or velocity make.

 

^ +1

 

If the engine was restricted in the intake tract, smaller runners and valves would help. You want good velocity in the runners to help keep the air moving and throttle response. I forget the exact number but something like 200 or 300 ft/s is what you want to shoot for. Since we have forced induction, it's simply a matter of increasing boost.

 

200+CFM intake/exhaust

For example MEGAmini Stage3a Head moves 275cfm IN / 200cfm OUT

 

I read that Cosworth at one time made their own new Head not minis? But I went to the website and it is not there anymore?

 

Cosworth dropped their MINI product line last year or so. The heads were OEM castings that had been ported, polished, and built.

 

ive always wanted someone to make a twincam head for this car with vvt tech... but that would be WAAYYY to expensive... for not much gain.

 

KA20 Type R heads can floew MASSIVE amounts of air! i think they are about 330cfm stock! There could be MASSVIE gaisn to be had with a new head design. the problem is who is going to buy them? there aren't sudfficent numbers of people willing to buy a new head for serveral $K and thus the business modle dose not work.

Chris.

 

Why should a business model be required? For a true enthusiast shouldnt there be every reason to try and improve no matter what? I would not think it would require very much money with todays computer modeling capabilities. Once a design is set into motion, only the molds and cost of material would be the real remaining cost if the research is done properly.

I would like to do this for me. I would not let making money be a focus. This is purely for improvement of an already great car.

I would like to see a head design that would allow the leanest burn possible while still creating power. The greatest focus would be on driveability. I see no reason why a powerful engine shouldnt be driveable and fuel efficient.

 

Your idea of having a lean running car being fuel efficient is totally wrong.

 

Please explain. This is why I started this thread. I can say that I know of vehicles that run lean for fuel mileage so I am curious hear your reasoning.

Thank you.

 

but more then ~12:1 under wot could be dangerous ( heat )

 

Does anyone have good photos of the Cosworth or other ported head? I found a complete extra stock head and I started to take it apart tonight. I have worked on heads and manifolds before but never ones for the Mini. I already have a good idea of what I want to do but it never hurts to see what one looks like which was developed on a flow bench.

Not certain if this is close enough to the original topic but since people were talking about aftermarket heads modifying the stock seemed appropriate to add.

 

To elaborate on 2mD's comment, the ECU attempts to maintain a stoich air/fuel mixture of 14.7:1 up until 80% throttle. At this point, the computer goes into WOT mode and throws in all the fuel it can. In addition, the ECU ignores the MAP and O2 sensor readings.

Fuel acts as a burning agent, cleaner, and cooler all in one. In non-boost conditions, you can get away with leaning out the engine to 12-12.5:1. In boost-fed conditions, you need more fuel because more heat is being generated. In this case, a ratio of 11-11.5:1 is preferred. If you are running an old-school carbureted engine, the rule is to pull your plugs immediately after making a couple of hard acceleration passes and observe the color and/or deposit conditions on them. Since the ECU throws in all the fuel it can, you can do the same thing. Or you can get an exhaust gas temperature (EGT) gauge to make sure the engine is not running too hot.

 

I called and talked to Cosworth. It seems that someone here on this thread was half correct..they no longer have heads for sale as of last year. But incorrect about the castings. According to Cosworth they had their own new casting made up in house. It had to do with the cost that mini was going to sell them to Cosworth and them making there own which was cost effective better for them. He did not elaborate if any improvements were made other then the parts choices and porting. He said that they used valve springs made to oem specification for the single spring head and for the dual spring head another aftermarket spring company called Ferra. It was hinted that they improved the cavity area were the water goes? Not sure what he was talking about something about emission and high combustion temperatures of the stock one? He said the reason the head and parts are no longer for sale was lack of expected sales. They sold the remaining stock of completed and bare heads and have no future intention on offering them again.

 

Guys this is the kind of data I'm talking about. Thank you. Now, I want to figure out how to bend those rules. I do know that with a carburetor or port injection (like the mini) the above chart very much applies. I believe the book has been rewritten for direct fuel injection though.

Head modifications are a welcome subject here. I almost bought an MCS head last week by decided against it for now. I am researching in little bits to try and find all the data I can before digging in.

JumpingJackFlash, I have tuned naturally aspirated engines before and know that you can get pretty lean with them. The boost is new to me and I appreciate the suggestions. I think I may be investing in an EGT sensor soon. I would be curious to see what the temps run on these cars. The temperature issue is one of the things I want to try and figure out how to deal with. If the heat can be controlled or even better, utilized, to allow for a closer to 14.7:1 mix WOT then we will really be in business! Maybe I need to be buying a whole engine and build a test stand with all the necessary components to run the engine out of the car. Trouble is, then I have to figure out how to load it... This is looking to be a ridiculously fun project.

 

Have you ever done anything like this before?
If not, your walking into a whole world of trouble and cost, which will probably end in a failure!

I don't want to seem negative, but this kind of venture is very complex and costly, and i'm talking from experience!

However that said, if your an engineer and have the budget and time to dedicate to your idea, then I for one wish you good luck.

 

MiniCobra, They may have been talking about a hot spot which causes the motor to be susceptible to early detonation which I suspect would cause the engine management to be more conservative on ignition timing.

I am new to Mini and I don't know the flow path of the coolant but as an example the Corvette LT1 (1993??) used a reverse flow coolant path which flows through the heads first. The prior year motor of the same displacement was around 265HP and the LT1 raised the bar to 300HP with a major difference being the flow path of the coolant. I believe this allowed them to increase the compression ratio without early detonation. I had a 1995 and it averaged 21 to 23 mpg combined and got close to 28mpg, strictly highway, at an average speed of around 70mph; not bad for 300HP.

ksminiman, to be in line with what you are looking for I think improving the burn efficiency is what you need to concentrate on and to improve it you need to understand the current situation to see how it can be improved. As Czar was getting at there is a mountain to climb.

One thing people spoke about with old school stuff and still applies here is how the spark plug electrode can change the flame kernel. As I mentioned I took apart a spare head. It still had the spark plugs in it. They are not all at exactly the same rotation and there is an optimum. I am not certain what rotation is the best but the electrode blocks the flame. Ideally you would like the fuel/air mixture to explode exactly on queue and completely consuming all of the fuel mixture but what happens is the spark ignites the flame and the flame races through the combustion chamber. If you know the optimum and you have enough spark plugs you can index them in each chamber so they are the same.

To make the production head Mini had to also keep cost under control and they had to account for manufacturing tolerances. They left a lot of surfaces as-cast and they seem to have been conservative on especially the exhaust port. I still haven’t seen good pictures of a modified head but I can see how undersized the factory exhaust side is compared to the gasket.

If Cosworth pointed out there is a hot spot I wonder if something like extrude-hone on the water side could also help to take out thick areas and make the water flow around the combustion chambers better.