John_C wrote:Short of changing the camshaft to a higher lift item I think the best thing you can do to a TR7 is to remove the original fan and the whole pulley assembly and stick an electric on. K&N air filters might not do a darned thing other than affect cold running... badly.
The only reason for fitting a higher lift camshaft to an engine is to allow more air/fuel mixture into it. More air/fuel mixture is the only way to get more power from an engine. It must of course be the right air/fuel mixture. Letting in more air with the same amount of fuel simply gives you a lean mixture, overheating & poor running. Thus fitting good air filters badly, [not properly tuned], will be detrimental.
The fact that a 7 goes into fuel starvation when the horrible stock filter is replaced without any increase in fuel shows how restrictive the filter really is. I doubt a high lift cam would have much effect, other than to make the idle rough, when you stop any extra fuel air mixture getting into the thing with that restrictive filter. I wonder how many have been disappointed after fitting a "sports" cam, when they did not retune the inlet air system.
All these things must work together. Just fitting a set of extractor headers will not do much for performance if you don't also fit a better muffler system, & a larger bore tail pipe.
I did once mention loosing 500 RPM off the top of my Cosworth Ford Brabham F2 rev range, when the back 15 inches of pipe fell off during a race. The thing just dropped it's bundle 500 RPM earlier without the extractor working properly.
An even stronger example of restricting the inlet air flow was with my new 1962 Morgan +4. In those more easy going days, Morgans did not bother with air cleaners, as it was hard to fit any with their bonnet shape. When I ordered the car I ordered the optional air filter system.
This consisted of an air box, similar in many ways to ours, but tapered from front to back to fit behind the bonnet, with a single filter fitted at the back. This was behind some bonnet louvers, so had access to cool air.
The first time I did a speed run with it, I was horrified to find it went onto 2 cylinders at 85 MPH, about 4250 RPM. The back carb took all the available air, starving the front 2 cylinders. As I knew unfiltered +4s did not do this I suspected the air filter system. With out tools with me to unbolt the air box, I simply removed the air filter from the box.
With this air flow restriction removed the thing would happily rev to 55000 RPM, & I expect to destruction if asked. I had learnt the performance robbing effect of restricting the air flow. That Morgan never again saw an air filter, & none of my cars have since had restricted air flow.
As Beans says, the tuning must be right. Note, I don't use K&N filters on the 7, although we do on the 8, I use Ram Flow filters. I also don't bother with a cold air feed on the 7, although I do on the 8. With the 330 BHP 8, & the 255 BHP S2000 Honda, I don't treat my 7 as a performance car at all. I have it because it is the nicest car I have ever driven on a long trip, & has "adequate" performance as the saying goes.
Incidentally, I'm not sure changing to electric fan will increase the power available at the clutch, depending on how good your natural non fan assisted cooling is. The twin fans on the 8, one in front & one behind the radiator draw 35 amps when both are running. I doubt the engine driven fan requires that much power. If they had to run at high performance operation, rather than just in heavy traffic operation, I think they would be detrimental.
Just my thoughts.
Hasbeen
