The cam we were using for the first run of AHX12 in 2002 and 2003 was designed and built especially for the engine by Dema Elgin of Elgin Cams.
We had asked Dema to build us up another more aggressive cam because we felt the dyno results on the first one he supplied produced may have been part of the reason why we only managed to get about 165 BHP from the engine.
I felt that we should, with no decrease in torque, be able to move the power band up the rev range a little and thus get closer to the 200 BHP that I felt the engine was capable of.
As it turned out the cam really didn’t have the desired results and although we managed to get up to 178 BHP after spending all day on Barry Sale’s PHP Racengine’s dyno we were unable to make the engine rev higher and the power still dropped off at anything over 5500 RPM.
During the 2003 event we started having some oil pressure problems. Sometimes it was low sometimes it was high but it was not consistent and we couldn’t establish a pattern at all. We finally put it down to dirt in the oil pressure relief valve because after we cleaned that out all was well for a while but, eventually, the problem returned and it was time to investigate further. When we pulled off the pan we found that it was filled with steel flakes and upon further examination we found that several of the cam lobes were very badly worn, and this after only about 2700 km of use.
I was some upset when that cam went south, particularly after all the trouble I had taken to install and break it in correctly and the additional expense we had incurred to use Valvoline Synthetic Race Oil but concluded that perhaps we were overstressing the lifters with the added lift.
Prior to the 2004 Targa I rebuilt the engine with the cam that Dema had originally supplied and we decided, for no particular reason to use Valvoline VR1 20/50 Race Oil. This time we had no cam problems even after the engine ran 10 km with no oil!!!
Well recently I received a copy of an article written by Keith Ansell of Foreign Parts Positively Inc. and it looks as though VR1 may have been a good decision. The general gist of the article is that the quantity of EP additives in modern engine oils is being decreased markedly because these chemicals reduce the effectiveness and eventually damage catalytic converters. This is not such a problem in modern engines with roller cams and rockers but with our old flat tappet technology this spells disaster. Fortunately it seems that the VR1 still has the higher EP content as does Redline but they seem to be the only oils which do. Keith has promised to send me an updated version of his article as soon as possible which I will post here for those interested.
With a 100S head, diesel crankshaft and Elgin cam this is pretty well a unique engine. I’ve never heard of another like it that’s for sure. After some very hard racing miles including one seizure and 10 km at race speeds with no oil the engine was due for a rebuild. The block I originally used was bored out so far that some of the repositioned head studs, required for the “S” head were very close to the cylinders. The replacement block has 3.45” bores and the stroke is still 3.996” bringing the capacity down to 2490c.c. but hopefully resolving some of the head gasket issues that have been causing some reliability problems.