ROBERT BARRIE
More from our resident racer
It was time to renew the Historic Technical Passport on an early 911. A simple enough task, you might think. Read on! The HTP – or, as it’s more popularly known, FIA papers – confirms the car corresponds to a period spec and allows it to compete internationally. It’s more or less mandatory for any serious form of historic racing. The complication in this case is a change concerning early 911 exhausts. The required manifolds are now the ones in the model’s homologation papers. That is as it should be, perhaps, but not what it has been.
The homologated manifolds have not been needed until now. The car I was working with was compliant when last inspected, but not any more. I don’t recall any consultation on the subject or any announcement. To be fair, I cornered a relevant FIA official at a race meeting last season and he was as helpful as he could be under the circumstances. More to the point, I’ve never seen a set of the original manifolds and I doubt anyone has ever raced with them.
There’s a very good reason for their rarity. It seems they were only fitted to a small number of the very first cars. The relevant homologation papers are dated late1964 and the manifolds changed early in the following year. It’s an unusual situation, but it’s not unique.
There are recognised anomalies and errors in many other papers – I am not sure anyone expected us to be looking at them some fifty years or more later. So, what is to be done? The solution is to amend the papers.
Appendix K – the encyclopedia of the rules and regs of historic racing – needs to carry a clause permitting alternative period-correct manifolds. That will take us back to where we were before and where we have always been. The FIA have said they will listen to evidence on the subject. We might get there in the end, but it’s unlikely to be soon. For now, if you need an HTP you will also need a set of manifolds.
The search was on. I found some repro manifolds with heat exchangers in Germany. They would suit an accurate 901 restoration, but they weren’t right for a race car. I couldn’t find anything else and so decided to make my own. When I say make my own, what I really mean is ask the nice people at BTB Exhausts in Daventry to make some for me.
Obviously. We studied the blurred picture in the homologation papers that constitutes the pattern and noted the end-point dimensions. They then set about coming up with something suitable. I dropped the car off and, after a short interval, came away with some new manifolds fitted. They look great.
They run straight back from the heads to the silencer in short and rather unequal lengths. I retook the relevant pictures on the HTP application and resubmitted it. I’m almost certain the manifolds were accepted. I can’t be completely sure, because the application was turned down for other reasons. Are we having fun yet?
Let’s assume the application is approved in due course, the question will be what to do with the manifolds. Initially, I planned to take them off, fit the more familiar, but still period-correct, type required by the 2-Litre Cup regs and get the car ready for next season.
Incidentally, if the idea of fitting some parts to get the paperwork needed to go racing before taking them off and fitting some others when you actually go racing strikes you as odd, then historic racing is probably not for you. Not only is it odd, of course, it’s also quite expensive.
I have almost worked this out, but not quite. Instead, I have been wondering if the manifolds can be made to work. A short and gentle drive after they were fitted went better than expected. Interesting.
So the new plan is to take the car to a rolling road to see what can be done with some different jetting and a clever silencer. Silencers are free under Appendix K – it seems you can do more or less what you like. Again, if you are looking for the logic in all this then, once again, historic racing is probably not for you.
The other possibility, now the issue has been raised, is that a race organiser might decide early 911s should race with the homologated manifolds fitted. That won’t be the case in the 2-Litre Cup, but a well-known circuit in the South East is considering it for one of its high-profile events next season.
I have politely suggested they might like to reconsider and they have politely replied that they might not. It’s their race meeting and their call. We’ll see what happens when it comes round in the spring – it may be that my rolling road work comes in handy after all!
In the meantime, if you need a set of the new exhaust manifolds, do have a chat with BTB Exhausts. And before you ask, no, I am not on commission!
“IT’S AN UNUSUAL SITUATION BUT IT’S NOT UNIQUE…”