View Full Version : ram pipes against K&N's help needed - newby

11-22-2004, 08:18 PM
Hi all, well this is my first post on this forum, I have a spitfire 1500, wich other than the g/f mini city is really my first classic & I am looking to find out what will ber the best to fit to my twin su carbs a set of K&N's or a set of ram pipes, any other advice on the old girl would be greatly apprieciatted, thanks a newby....... /ubbthreads/images/graemlins/cool.gif

11-22-2004, 09:04 PM
Hi spitfire1500 and welcome. You will need some sort of filter to keep all kinds of stuff from going into the carbs. K&N's are good, and won't break you. Wayne

11-22-2004, 09:14 PM
K&N filters with short, radiused stub stacks are even better. The stack directs the airflow into the carb. better.

11-22-2004, 09:25 PM

I'm relatively new, too, and have found folks here friendly and helpful!

Regarding your question, why not do both?

Get the right size K&Ns and you can fit some types and sizes of ram pipes inside them. I think in an ideal world they'd like to have 1.5 to 2 inches of "breathing room" between a ram pipe and the top of the filter. I've got 3.5" deep K&Ns on the Webers on my TR4, am currently shopping for a set of 2" ram pipes. All but the really expensive, full radius, billet ram pipes will fit within the K&Bs.

The biggest concern besides not blocking the ram pipe with too-close-fitting filter is underhood space to accomodate a larger filter assembly. I'm not all that familiar with Spitfires, so you'll have to be the judge. I think I'll be doing some rearranging on the right inner fender on my car, when I reinstall the engine!

K&N are good. I use them on all my cars. But not my motorcycle which has Keihin carbs that are similar to SUs. When I fitted an "oiled filter" like the K&N, the bike began running way too rich. Rather than rejet it, I went back to a paper filter element. There are other issues with that motor, though. So, in fairness I can't lay it all on the filter and it wasn't a K&N. That might have worked better. It's just hard to justify a $50 air filter on a $500 motorcycle!

There are other filters out there, such as ITG, that are equally good and might fit in some places K&N don't. However, K&N does offer a lot of different sizes.

There are also K&N and other filters that are made to clamp onto an intake tube or ram pipe. Sort of depends upon the shape of the pipe, whether these might work or not.

BTW, a shorter ram pipe generally helps the lower to mid rpms, while longer ones are used to improve the high end. So, shorties that fit easily inside a filter assembly might just be the ticket.