racer88 Posted October 7, 2010 Share Posted October 7, 2010 (edited) I have read all the threads on dealing with the exhaust smell in the drivers compartment. My 260 has a fresh 280 engine with many upgrades. My SU's are tuned properly, car drives great, idles down to 700rpm pulls strong and plugs look great. At idle with the windows down you get fumes in the car, widows up no fumes. In my youth I drove many cars from the 60s with holes in the floor, exhaust leaks etc. with no fumes in the car. My question is does anyone have an opinion why our cars smell so bad. Is it a function of the su carbs or the lack of efficiency in the cylinder head. Everyone seems to focus on keeping the fumes out of the cabin but not the fumes themselves. Any ideas would be great. Bob Edited October 7, 2010 by racer88 Quote Link to comment Share on other sites More sharing options...
Leon Posted October 8, 2010 Share Posted October 8, 2010 Frankly, if you really read all the threads on cabin fumes, the answer would be given to you. It has to do with the aerodynamics (or lack thereof) of the Z. There is a large wake, a low pressure area, behind the car which traps the exhaust. Opening the windows drops cabin pressure, exacerbating the issue. Sometimes I run the fan, which helps but gets annoying when turned up. Quote Link to comment Share on other sites More sharing options...
racer88 Posted October 8, 2010 Author Share Posted October 8, 2010 (edited) Frankly, if you really read all the threads on cabin fumes, the answer would be given to you. It has to do with the aerodynamics (or lack thereof) of the Z. There is a large wake, a low pressure area, behind the car which traps the exhaust. Opening the windows drops cabin pressure, exacerbating the issue. Sometimes I run the fan, which helps but gets annoying when turned up. Hi Leon I think you missed the point of my thread. I was not how do the fumes get in to the cabin, but why do our engines create as many fumes as they do. As i stated in my post I have been around engines from the sixties and seventies all my life and have never had engines that smell as bad at idle. Any thoughts on that Bob Edited October 8, 2010 by racer88 Quote Link to comment Share on other sites More sharing options...
Derek Posted October 8, 2010 Share Posted October 8, 2010 Not trying to be snarky but take any engine from the 60's pump the exhaust into a room the size of the z cabin and It would probably smell. With the windows open and moving the back of the z is a vacuum cleaner. Derek Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 8, 2010 Share Posted October 8, 2010 Not trying to be snarky but take any engine from the 60's pump the exhaust into a room the size of the z cabin and It would probably smell. With the windows open and moving the back of the z is a vacuum cleaner. I think that's right. Most cars don't have leaky seals around the back and a shape that draws the exhaust into them when the windows are rolled down. If you want to get rid of the gas smell, go FI and put a catalytic converter on. Quote Link to comment Share on other sites More sharing options...
racer88 Posted October 8, 2010 Author Share Posted October 8, 2010 Thanks everyone for your input. This is my first zcar. I love the car but sure do like to drive with the windows down . Maybe the gas fumes just smelled better back in the 70's. With the crap they put in the fuel today that's probably not far from the truth Bob Quote Link to comment Share on other sites More sharing options...
jtmny1999 Posted October 8, 2010 Share Posted October 8, 2010 i dont think it has to do anything with the engine, I have a RB25. And let me tell you, it still smells lol Quote Link to comment Share on other sites More sharing options...
Lazeum Posted October 8, 2010 Share Posted October 8, 2010 Are you sure you're smelling burnt fuel? I have a very smelly car, it was because some hoses in the cabin were rotten, gas vapor was going into the cabin. Replacing the hoses fixed the issue. Quote Link to comment Share on other sites More sharing options...
Leon Posted October 8, 2010 Share Posted October 8, 2010 A smelly exhaust can be caused by many things, a few already mentioned here. Your mixture may be too rich, you may have leaking hoses in the engine bay, an exhaust leak, expansion tank hose leak, etc... People have put catalysts on their carburetted cars and reported that the smell is much less severe. You just better have your mixture dialed in or you'll destroy the converter. Otherwise, switch to EFI as Jon put it. Like I initially said, the main problem comes from the aerodynamics and 40-year-old rubber seals of the Z-car. Quote Link to comment Share on other sites More sharing options...
johnc Posted October 8, 2010 Share Posted October 8, 2010 I prefer Spank-um Berry. http://mpioil.com/renegade_scents.html Quote Link to comment Share on other sites More sharing options...
JayBee280 Posted October 9, 2010 Share Posted October 9, 2010 I have read all the threads on dealing with the exhaust smell in the drivers compartment. My 260 has a fresh 280 engine with many upgrades. My SU's are tuned properly, car drives great, idles down to 700rpm pulls strong and plugs look great. At idle with the windows down you get fumes in the car, widows up no fumes. In my youth I drove many cars from the 60s with holes in the floor, exhaust leaks etc. with no fumes in the car. My question is does anyone have an opinion why our cars smell so bad. Is it a function of the su carbs or the lack of efficiency in the cylinder head. Everyone seems to focus on keeping the fumes out of the cabin but not the fumes themselves. Any ideas would be great. Bob I have a 280z L28 and i had terrible problems with a smelly exhaust. But beings the 280 was fuel injected i took the air flow meter and leaned out the fuel mixture and it completely got rid of fumes. One window down one up.....no fumes. both windows down no fumes. both up no fumes. Idle no fumes. I never have problems since then and my eyes used to burn sooooo BAD. But idk the correct procedures with working with SU carbs but whatever steps you take/took to get them tuned. lean out the fuel. And plus to make things every so better my car runs so much stronger through the rpm band. O and i have leaks and holes everywhere for fumes to be bad and they are no longer are present. I promise the results will be more satisfying weather you gain or lose any horses in the process. Quote Link to comment Share on other sites More sharing options...
duragg Posted October 9, 2010 Share Posted October 9, 2010 My 1989 560SEC Benz has no cats and even with perfect 14.7 idle mixture it stinks. That is one of the benefits of Cat-Converters...smells like a "Summer's Eve". Quote Link to comment Share on other sites More sharing options...
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