Cars
PROJECT CATERHAM R400Well having spent the last two years banging on about the merits of Honda power we thought is was about time we once again practice what we preach! The plan to start, is to replace the car's original highly tuned Rover 1.8 k series with a standard Honda 2.0 iVTEC engine while maintaining/exceeding the R400 "quality factory feel". Although the factory R400's performance has never really been in question it's low to mid range drivability has and it is this along with the fragile nature of the engine that makes this conversion potentially worthwhile. P.S>And the fact we can reliably tune the Honda to levels the Rover K series becomes a boat anchor!!!
10/10/2005
The finished engine package complete with induction, exhaust system the and new dry sump were installed on the engine dyno so we could run the engine before installation. In theory as we have used the same spec engine several times before in wet sump form so the map should have been correct but we thought we would try using the Caterham's original secondaries and silencer as this would keep costs down. Running the engine up also allows us to check the basics of the engine such as oil pressure and VTC operation. The latter has been known to stick if the engine has been left standing unused for sometime. A stock 195 bhp UK spec engine fitted with roller throttle bodies, the correct length 4-2-1 manifold, 2.5inch exhaust and silencer and mapped EFI ECU always gives 240bhp + or - 2 bhp. Up to about 5000 rpm things looked as normal but after that the fuelling started to richen up and the engine lose power on what is expected. Finally it gave a pretty bad 218bhp AHH!!!. We could have tried to weaken the fuelling out which may have helped a bit but having previously spent along time getting the map spot on the first choice was to check out the exhaust. The Caterham came to us with a 2.25inch silencer and we usually run a 2.5inch one so this was the first to be swapped. This gained a surprising 10bhp but whether this was due to the extra size or the fact the 2.25 had no packing left in it we did not have time to check. Next on the case were the Caterham's secondaries which were longer than our standard setup so we quickly shortened them and ran the engine up again. The result was that the fuelling was now spot on without any map changes and a peak power of 236bhp and 168lbs/ft. This is still a touch down on what we hoped but the engine did have less than 2000 miles on it and a shorter overall exhaust length all things we will investigate in the future.
30/08/2005
The stock Caterham has a clutch operated by a cable which bends tightly. These often break in standard form so expecting it to cope with the stronger clutch spring of the Honda is not a good option. A bigger cable may stop the breaking issue but you would still need legs like Mike Tyson to operate it The solution is to convert it to a hydraulic system which involves fitting a clutch master nd slave cylinder. We could fit a slave cylinder to the standard cable arm but different size clutches need different size and shape release bearings and these are easily available for the concentric slave cylinders meaning we can use 5.5, 7.25 or 8.5 inch clutches depending on application. As a full house option it is possible to make a small diameter flywheel and twin plate 5.5 clutch but this requires using different starters pushing up costs and reducing service life. For this application we have gone for a heavy duty standard size single organic plate with the correct offset which will give a long service life and smooth traffic manners. This has been mated to a lightweight flywheel and heavy duty pressure plate. Finally an adapter boss had to be made to mount the concentric bearing which also carries the gearbox seal and locates the gearbox bearing. As the slave cylinder is now inside the bellhousing a remote bleed nipple was also added so clutch bleeding does not require the engine to be removed!
25/08/2005
The gearbox was put back into the car and bolted to the mount. As the bell housing is exactly the same length as before the plan is to make engine mountings that fit back on the original holes on the chassis as these points are braced for strength. In a transverse Civic install the main engine mount comes through the timing chain cover but with the Caterham install as we did not want to start cutting the chassis about these needed to mount from either side of the engine. On first inspection this seemed straight forward as there are plenty of bolt bosses to make some relatively simple mounts however that was until you started to factor in the dry sump pump. Which ever side this was mounted it obstructed some of the availible bolt holes on the engine and went straight through the engine mount. This resulted is the left hand engine mount having to be made like a large polo mint with the pump running through the middle. These mounts are only tempory place holders with jigs and proper mounts to be made later. Other mounting issues involved the install angle. At it's natural angle it is canted to the left by about 15 degrees. Ideally we wanted to keep this the same as these engines have a lot of oil going to the top and so have four channels back to the sump. Two drain the oil down and two a bit higher to let the air up. If the engine is stood upright it may cause drain issues as all the holes will be the same hieght. In the end with all factors considered the engine is mounted at about 12 degrees which also makes the vertical hieght of the engine less than an upright install.
21/08/2005
There are a number of ways to sort the bell housing, solid billet, new casting, adapter plate etc. Having made a bell housing before out of solid billet for someone with more money than sense we liked the idea of making changes to individual applications but considering we may make a kit in the future then this was ruled out on cost. We ideally want a semi finished casting which would allow us to change the engine angle and bell housing depth for different applications and this ultimately will be the way to go in terms of cost and flexibility. However being very impatient they was no way we were going to wait 6-8 weeks for a bell housing that would mean we could not get on with the rest of the job. The most common way for one off jobs is an adapter plate but this has its problems. The extra depth means the clutch disc does not run on the gearbox spline fully and in this case the larger Honda flywheel did not fit in the Caterham bell housing anyway. Our solution was to machine 30mm of the stock bell housing and then weld on a slightly thicker aluminum billet. The engine and gearbox mating faces were then digitised a mounting jig made and then a recess machined to take the stock flywheel. The mating surfaces were then faced to remove any distortion caused by welding to leave a bell housing the same depth as the factory item.
17/08/2005
There seems to be a lot of "thinking" and not a lot of action at present. The plan was to fit the engine with all the stock components to keep the cost down and then offer upgrades as options such as lightweight alternators, performance manifolds, dry sump etc. As with all the best laid plans this may need to be tweaked a bit as there seem to be a "few" minor issues. Without stating the blindingly obvious the Caterham is a small car and the Honda quite a big 2.0l engine or maybe we should say tall engine and short car. Dry sump it is then! The throttle body points toward the back of the car straight into the footwell. We might be able squeeze an intake pipe on in this instance as the car has a short footwell and dry sump tank but as some cars don't have this is would be nice to have one solution. Roller throttle bodies it is then! The steering column goes straight through where the exhaust manifold, oil filter and cooler go. Custom exhaust, remote filter and new oil to water cooler look on the cards. Other issues involve the fact the flywheel is to big to fit in the bellhousing, the engine loom is long enough to fit the ecu in the boot, the alternator and dry sump pulleys are currently somewhere buried in the chassis rails. Anyway on with the first job, do away with the Honda tranverse gearbox and attach the Caterham 6 speed inline one.
14/08/2005
Here goes! One Caterham with number 2 con rod though the side of the block arrives along with one 20000 Honda 2.0 iVTEC straight from the breakers yard. First task is to simply strip out the engine and box something your average Kwik-Fit boy could do so we won't bore you any longer. Any questions look in a manual!! After that the first job is to find a lot of bits to make a dummy engine instead of using the one to be installed and work out if there are any potential "issues".