View Full Version : free flow exhaust?

12-17-2004, 11:18 PM
Any ideas here? Once again, still new to this car stuff, but the exhaust is needing some serious attention, and I'm wondering about the varied options. I'm liking the idea of the free flow performance, but can't seem to figure out if the car need to be FI, or if modifications are made for the FF system. Anyone else have to make this decision? I might also lean towards a standard stainless steel system, but I might be able to get a better deal on the FF.

Thoughts re: installation, performance etc...?

12-18-2004, 02:38 AM
Hello Cmac,
you can get some power improvements by installing a good exhaust manifold, the best seems to be a 6 - 3 - 1 configuration, although I believe that there are 6 - 3 - 2 versions for the TR6. Do you mean fuel injection as FI?
The UK spec Lucas Petrol injection is a good performer but teh exhaust I mention also works with carburettor engines.
By the way forget free flow, that is not how exhausts work.


Bob Buxbaum
12-18-2004, 08:40 AM
A few things to touch on.

Free flow exhausts can mean a) no muffler or b) low restriction muffler. So I'll use other terms.

1) Standard exhaust style can be mild steel or stainless components from the standard cast iron manifold to the tail pipe end. Benefits are cheap for mild steel, expensive for the S.S., and fit should be a no brainer. Also quiet.
2) Performance exhaust could be a header into a standard style exhaust or into a mild steel or S.S. low restriction exhaust. A low restriction could have a glass pack type muffler and maybe a resonator. If you have only a muffler then a free flow style will be good. If you have both you can eliminate either the glass pack or resonator for less restriction. Down side is cost, which increases as more stainless steel is added. But stainless is forever (practically). Benefit is performance. Also, the deletion of either the muffler or resonator adds noise.
3) A completely free low (no mufflers) is a mistake for street use. You'll hate the noise, everyone else will hate the noise, and the engine won't like it, either. Bad plan.

I have a TR8 that I put a full stainless system on; headers, resonators, tubes, but no mufflers. Somewhat loud, but SWEET. The engine has been mildly modified and sounds like a lot more than 3.5 liters! But it's a bit noisy. The mufflers will most likely be going on in the spring. I have heard one with mufflers and resonators and it sounds real good. So,.......

If you plan on a full sport system you should get a Rimmers catalog and take a look at the systems. NICE stuff. When I bought my stuff from Rimmers the dollar/pound exchange rate was a LOT better. I don't know about the Canadian dollar/pound exchange. The first important issue is selecting the tube header. There are real differences in the 6-3-2 and 6-3-1 types. One LOOKS nice, the other WORKS nice. But there can be SERIOUS fitment issues around the frame rails and clearance problems to the ground. Also, header length to the first collectors can have a real effect on the power curve, even with a stock engine. All the other issues are secondary and simpler, such as single or dual exhaust, cost, vendor, etc. Try hooking up with a local TR club and go to some all British cars show to see what the TR, AH, and MG guys are hanging on their cars. The more information you have the better equipped you are to decide. Almost everything I learned was from GOOGLE searches, catalogs, and message boards. Try this Spitfire and GT6 board https://members.boardhost.com/GT6-Spitfire/?968006626 as there have been a bunch of threads about just this topic. Since the GT6 (my other TR) and TR6 engines are so similar most discussion applies. If you are running F.I I can't suggest what to do for the increased flow (lean condition) that a more open exhaust will cause. If you have cabrs, you'll simply have to slightly richen things up.

But when you are done YOU'LL LOVE IT !!

p.s. Don't waste your money on Monza exhaust. Sounds okay, looks good, falls apart.

12-18-2004, 10:24 AM
Awesome! I now know 100% more than I did! Thanks guys!


12-18-2004, 12:46 PM
For what it's worth:

I've got a 71' TR6 with a "S2 cam". Stock exhaust manifold. One single straight piece of Mild Steel pipe going back to a burnt out Glass Pack muffler, and a fancy chrome tip on the end.

The car sounds very cool. I get lots of compliments on the sound of the car. Lots of peolpe say it sounds like a Harley Davidson with Drag Pipes. It's fun to play with the exhaust sounds while driving. It Growls when I get on it, and it "Snap, Crackles, and Pops" when I let off.

While it's great for cruises, and playing around,...it is too loud for a long highway type trip. I drove the car home from Austin Texas to Maryland over the summer. I can tell ya it's too loud for that kind of driving. My ears were ringing everytime I stopped for gas.

Now that I got the car home I mostly do short trips in it. Car Club Cruises and stuff like that. The car sounds too cool to change the exhaust. But if I was gonna go on long drives at highway speeds on a regular basis I'd probably tone it down a bit.

So I'd consider how you intend on driving the car when your deciding on the Exhaust.