I have a 40 Ford 2dr sedan . I am getting exhaust fumes inside of the car there are no leaks in the system. I am wondering if I should extend my tail pipes or shorten them. Currently they are 6 " past the body.
Cab venting issues. How does fresh air get in and out the cab. Should flow in the front from outside the engine bay and out the rear, away from the tail pipe.
This might explain your problem as explained on the internet search. "At certain speeds beyond a crawl, the space right behind the vehicle’s trunk and rear window is basically empty or seemingly like a vacuum. These empty spaces are caused by the air molecules not being able to fill the hole as swiftly as possible. The air molecules try to fill in to this space, but the vehicle gets one step ahead each time." Plus, there is no back bumper to breakup the airflow as it flows off the trunk. I also wonder if the downward bend in your exhaust tip contributes to the problem? Are you sure there are no exhaust leaks in the exhaust system before it exits the exhaust tips? Just for the heck of it, try extending your exhaust pipe tips further out from you tail pan. On my 40 the exhaust extends 9 inches out past the bottom of the tail pan and exits under the bumper. I also have a splash pan between the tail pan and the bumper.
Back when Detroit still built station wagons, they didn't run the exhaust straight back like they did on sedans but instead turned the pipes out before getting to the rear of the car. That put the exhaust into air running down the side of the car, dissipating it. And are you sure it's exhaust? If you're using your cowl vent, a lack of the gasket between the hood and cowl can allow fumes into the car.
Or they hung air deflectors on top or on the sides to eliminate the vacuum around the rear window. My 68 squire had them built into the D pillar.
Big air pocket & turbulence, try and see Some older cars after driving some miles you can see if there is more dirt / grim ext on rear of . My old A would be more dirty @ rear then front .
I would remove the turn downs and replace them with 4" (or more) longer straight extensions. You need to get the exhaust out behind the car so the air flowing over the trunk lid carries it away. 6" is probably good, but you start measuring that 6" at the farthermost rearward part of the trunk lid, and end at the farthest forward part of the pipe opening (which is the bottom of your current turn down). What I see there is lucky to be 2" behind the center of the trunk lid.
As been suggested, make sure all openings at the rear of the car are sealed. Trunk, taillights etc. Also, the tune of the engine will greatly affect what you smell in the car. Are you running a PCV system? Is it working properly? What is your AFR? What does the ignition timing curve look like? I go to lots of shows and cruises. It's easy to tell when a car drives by or you're following a car that's not tuned worth shit. Not so hard to get one to run. A proper tune is a whole different scenario.
I know most don’t realize what happens with air leaving different styles of bodies. Land speed guys are looking for ANY way to cheat the air. What I see here and kinda stated by gene-k above is the exhaust is not far enough away from the body as the underside air wraps around heading forward over the trunk. What the car needs is what Henry put on it…… a bumper 6” off the body and the exhaust ends being near it. This gives the air a place to go before the ends of the exhaust. If you still have the vent on the cowl crack it a little for air flow to “pressurize” the interior. Good luck.
Racing outlawed it because it worked too well. Fan cars removed the suck and got faster. I hear McLaren's F1 has a tail fan. A whole new use for electric fans.
I worked and worked to get the tailgate and lift gate on my 49 Chevrolet wagon to seal up. The fumes used to drive me crazy! As has been noted, make sure you get that trunk sealed well. The old dollar bill test will tell you where the leaks are.
With a normal 40 Ford bumper + bracket installed, the tip is a little short. With a custom bumper tucked closer to the body, you have style, but fairly enough room for a tap and crush situation on a “bumper to bumper” scene. So, the first thing is to extend the tip straight out and not down. That should alleviate the odd ball swirls that come out when you are idling. Even when you are going straight, the downward exit will have to push down and then get swept up and out back… Nice color paint and it needs protection first and that bumper and the new extended straight pipe should solve the problem, plus check out all of the ideas from everyone. YRMV Hello, When my wife and I bought this 327 powered 1940 Ford Sedan Delivery, we thought it was a street ready hot rod for use as a daily driver. We were so happy on the way home. But, upon close inspection, it was not road ready or safe. So, for the next 6 to 8 months, we spent a lot of time getting things ready. The engine ran fine and had the normal hot rod motor aroma. But, the drive line and suspension was just awful. It was unsafe at any speeds. My wife loved the sedan delivery, the 327 power and the A/C, but would not drive it after her test run down the coast highway. So, the months we spent getting everything right was a good thing. Now, we were able to include it in as one of our daily drivers. A 62 Corvair or a 327 powered Sedan Delivery with A/C? We all knew who drove the sedan delivery on her daily errands and visits to her friend’s houses, etc… AWWW! But, over time, when she came back into our small apartment, something was in the air. An unusual aroma and a familiar one at that. It was exhaust smell and that stuck to hair, clothes and even socks… since I did not drive the sedan delivery, those time when my wife drove it, the aroma of exhaust fumes over came what little perfume she wore. The “eau de cologne, parfum,” + other names all came to mind. But, this was “eau de exhaust.” To her, it was unnoticeable until she was the one in the small apartment and I was just walking in from a photo shoot or drive home from a surf trip. Jnaki So, for the immediate weeks to come, I spent countless hours checking the vents, the door jams and windows. Replacing the old worn gaskets and channels to new tighter fitting new ones. Checking the rear door rubber and the door window channel were the first to be checked and replaced. The exhaust pipes went through mufflers and out of the rear, under the bumper with straight pipes. But, for all of the checking, replacing and re-checking, it still had the aroma of exhaust ever so slight, but it was there. The gas tank was checked and a new cap was put on with a good seal. So, as the aroma still lingered, I moved to the pedals and sealed the floor joints. The one thing I noticed were miniature holes for the wiring and other through the firewall accessories. They were sealed with gaskets and grommets, but I had to replace several and use a clear sealer to fill up the openings. Now, with all of the grommets sealed and dash holes repaired, there was absolutely no aroma of exhaust and gasoline anywhere to be found. We both had a nice normal aroma from each other and no intrusion from the gasoline/exhaust gas smell anywhere. The extra time spent checking and double checking the whole car was well worth it. Now, it was hard to drive the 40 sedan delivery again, due to it being on the road with a long haired girl driving it all over the place. A 20 something long haired girl was unusual, driving the sedan delivery, but a girl driving the hot rod sedan delivery almost everyday was very unusual to say the least.
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