Inner Workings: Exploring the S2000's F20C Engine
by Shawn Church
Part 1 - Cracking the Cylinder Head Code
Welcome to the first installment of a new series at VTEC.net. With "Inner Workings", we intend to delve deeply into both the theory and practical application of performance enhancing technology on a variety of Honda power plants. This isn't going to just be a brief technology series, but rather an in depth exploration of performance with industry experts and hands on experiments.
Our first subject of interest is the amazing F20C engine from Honda's equally incredible S2000 roadster. The F20C, while employing little truly new technology, is arguably the most advanced combustion production automobile engine that Honda has ever produced. And it certainly wins the output and RPM contests, creating 240 hp from a mere 2.0 liters of displacement and redlining at a stratospheric 8900 rpm (with a 9200 rpm limiter!).
Some pundits might question why we want to start our new series with such a highly developed engine. After all, how much more power is there really to be found when you're starting with a specific output of 120 hp/liter? The challenge inherent to this question is exactly why we've chosen to explore the F20C. Additionally, our research has shown that the K-series head from the RSX Type S is a poor, but close relation to the F20C head, thus what is effective for the F20C should help the K20 as well.
K20 and F20: Brothers in Arms?
Other Honda performance engines, particularly the B-series VTEC units, have already been pretty well developed. Tuners have made obtaining another 50 hp from a normally aspirated and streetable B-series engine formulaic. Port the head like so, add cams from manufacturer X, exhaust, header and tune. But the F20C is too new for such easy power, and comes far more developed from the factory. Furthermore, the relatively small number of F20C's in circulation may mean that aftermarket development will take a bit longer, so we want to help the process along.
Finally, those of us at VTEC.net who've been around awhile remember well the history of the B-series engine in the U.S. When the B18C gained widespread distribution in the Integra GS-R in 1994, many "less-informed" persons stated that those truly interested in performance upgrades should seek to utilize the non-VTEC engines, as the B18C was "tapped out" from the factory. Of course, 7 years on and those individuals have been proven wrong many times over. Yet, history seems to be repeating itself with the F20C. Many persons, with uncertain qualifications, have publicly stated that there are minimal gains to be obtained on a normally aspirated F20C. Perhaps they are right, but we intend to find out for sure - and we suspect that there is more horsepower lurking in the F20C than people think. So, onward and hopefully upward!
There are a variety of areas we'd like to explore on the F20C. Exhaust tuning, camshaft profiles, ignition and fuel tuning and many more. However, one of the best places to start, and one which requires relatively minimal capital resources (important in this economic climate) is the cylinder head. The cylinder head is the ultimate limiter on how much normally aspirated power an engine can make. Add all the compression and the cam lift/duration you like, but if the cylinder head can't support the power, the results will be disappointing.
In light of these considerations, VTEC.net went looking for a cylinder head guru with a flow bench, expertise and the time and willingness to develop a totally new cylinder head. We found such a porter in Joe Alaniz. Mr. Alaniz (we'll call him Joe from now on) is the owner of Alaniz Cylinder Head Technology - ACHT for short (www.alaniztechnologies.com). We met Joe many years ago when he was working for DPR Racing Heads in Torrance, CA. Before developing his Honda skills at DPR, Joe cut his teeth at Valley Head Service, a renowned domestic head shop in Southern California. After DPR, Joe went to Southeast Asia for a year to work on a variety of racing research and development projects. Recently, Joe returned to the States and SoCal to start his own porting business. Armed with a Superflo flowbench and an unquenchable curiosity to learn, Joe was our guy. That he was willing to do the development work for free was a big bonus too - as you'll find out later, developing this head required hundreds of hours of time.
Here's Joe making a pull on our F20C head on the Superflow 110 flowbench. Note the earplugs and the tightly fastened shop apron. You don't want anything to get sucked into the port while the bench is running, and all that air moving is LOUD
The next step was to round up a spare cylinder head for research and development purposes. It takes a lot of trial and error to develop a new head, and that means that you can't use a customer head - the R&D head usually ends up looking pretty rough when all is said and done. Since F20C's are pretty rare, we weren't going to find a new one easily either. That meant going with a new casting from Honda. The price for a new head, valves, springs, etc. is not cheap, but we got lucky. We found a very dedicated group of enthusiasts at S2ki.com, a S2000 owners group website. A select few were very interested in cylinder head development, and agreed to share the cost of purchasing the R&D head for first dibs on the final results. A call to http://www.handa-accessories.com netted us the requisite parts at a good price, and we were in business.
The plan is as follows: First, baseline the stock head and valve combination. Next, begin working on the intake and exhaust ports to look for gains. Then we'll work on the combustion chamber and finally finish up with valve and seat profiles. Down the road we'll also experiment with intake manifold setups. Finally, we'll bolt what we believe to be the best flowbench combo onto a test car and see what it does on the dyno and the real world. Along the way, we'll share with you the results, both good and bad. Some things, like specific valve angles and such, we'll keep secret. Joe doesn't want to spend all this time doing free R&D only to have someone else duplicate his work just by reading the article!
So, we've got what looks to be the best flowing Honda head ever (and by all accounts one of the best flowing OEM heads on any engine, period). Think we can find any more flow? Hint: the answer is yes, but it wasn't easy. In our next installment we'll begin work picking up some flow on the intake side. In part 3 we'll cover the exhaust side and intake manifold. Finally in part 4 we'll try and put a ported head on a car and see what happens!
Copyright 2002 Temple of VTEC