Velict Posted February 16, 2019 Report Share Posted February 16, 2019 So my GB122 Sunny is on it's way to getting a new life. Something entirely unconventional I want to do is keep the EGR for emissions inspections that are an inevitability of living in Japan and certain states in the U.S. I've already read up on the datsun1200 forums but it seems that deletion of the EGR is always the smartest thing to do. Attached here is the EGR set up for an OEM carb of the GB122. It's the VVT style. https://photobucket.com/gallery/user/ddgonzal/media/cGF0aDpEYXRzdW4gMTIwMC93aWtpLzE5ODQwNkIxMjJiXy5qcGc=/?ref= I'm wondering as to what ideas would there or could there be to keep the EGR with aftermarket carbs such as the Weber DCOE or the OER carbs. Any help is appreciated. Quote Link to comment
datsunrides Posted February 16, 2019 Report Share Posted February 16, 2019 EGR really has nothing to do with the carb. In most older vehicles the ports are plugged with soot and they don’t work anyways. The only real problem you get is if the ports are clear and the EGR sticks open, you essentially get a vacuum leak. That is also how you can tell if they are working, if you lift the valve, or put vacuum to it, you should notice a drop in idle speed. You could keep the EGR if you keep the stock manifold and run a DGV or similar, but if you go sidedraft, pretty sure there is no such beast as a manifold with EGR ports. Quote Link to comment
Velict Posted February 16, 2019 Author Report Share Posted February 16, 2019 Yeah so that's why I was trying to think of an idea. Especially with multiple bodies/intakes you can't really tie them together to have the exhaust pull equally into each cylinder for combustion. I'm wondering if a hi flow cat would suffice for emissions. Quote Link to comment
datzenmike Posted February 16, 2019 Report Share Posted February 16, 2019 There is also the problem of the EGR tube from the exhaust eroding/rusting and letting outside air in. Exhaust is deficient in oxygen having uses it all in the combustion process. If oxygen gets into the intake it effectively will lean the mixture and loose power. If you can keep the stock intake you can run EGR. For anything else all the intakes runners would have to draw from a common plenum with the EGR valve in it. For individual runners with multi carbs you would need individual pipes to an EGR valve... not impossible but you would also have to satisfy the following.... 1/ There is no EGR at idle and why a ported vacuum signal from just above the throttle plate of the carb is used. As the throttle opens above the port, intake vacuum is applied. 2/ There is no EGR while the engine is cold and why a TVV (thermal vacuum valve) is used. 3/ There is no EGR at full throttle, again the ported vacuum signal 1/ drops to basically zero at full throttle. Quote Link to comment
Velict Posted February 16, 2019 Author Report Share Posted February 16, 2019 Which is why I was thinking a catalytic converter was a better idea.... Quote Link to comment
datzenmike Posted February 16, 2019 Report Share Posted February 16, 2019 Could be, but as the exhaust is oxygen poor how will you get the cat to burn up the emissions? The Z series engines used a passive one way reed valve on the air filter. A pipe was run from the exhaust manifold to the one way valve and the vacuum pulse directly after an exhaust pressure pulse was used too suck a small amount of air from the filter (the pressure waves would be stopped by the one way valve) down the pipe and into the exhaust stream in a train of little puffs. This would add much needed oxygen for the cat to work with. Quote Link to comment
Velict Posted February 16, 2019 Author Report Share Posted February 16, 2019 (edited) I looked that up and that has some incredible amount of work to deal with, on top of requiring custom work. I'm just wondering now if with the egr delete, I can still meet the requirements of 4.5% carbond monoxide and 1200 ppm for HC. Edited February 16, 2019 by Velict Quote Link to comment
datzenmike Posted February 16, 2019 Report Share Posted February 16, 2019 EGR reduces oxides of nitrogen. I don''t think it affects HC. HC can be reduced by... Running the engine as warm as possible for the test. Put new or hotter thermostat in Good ignition. You have an A12 so find an A series matchbox distributor and coil. Hotter fatter spark. Or at least new points, NGK plugs, wires, cap and rotor. Always check valve lash and set the timing. Adjust the idle mix as lean as the distributor will be able to fire. Run leaner primary jet. Make sure choke is off Make sure fuel level in the carb is within spec and not over filling. Check air filter is clear Fresh oil and filter. I've heard to run a half empty tank and throw a gallon of pure ethanol in. That would also lean out the mixture. Days before test do a "Coke bottle tune up". Ever blown a head gasket where coolant has been leaking into the combustion chamber? Ever notice that the piston top is like new and shiny and the combustion chamber mostly clean and the valves too?? Ever notice that combustion chamber is the easiest to clean? Warm engine up HOT, go for drive, idle with some cardboard part blocking rad. Take air filter off. Fill coke bottle (or anything suitable) with distilled water. Rev engine up and begin dribbling water into carb. Engine will slow and try to stall so rev even more and keep pouring. When empty check temperature gauge it will have dropped to the cold range. Let engine warm up to hot again and repeat. The sudden cooling effect from the evaporating water will crack and flake carbon and combustion deposits off the piston and the head and valves. What I did was pull the windshield washer hose off and shove into the carb throat, then go for a long hard drive. By using the washer switch I could do the same thing and keep going using 3rd gear. Washer mix is even better because of the alcohol in it. Quote Link to comment
DanielC Posted February 16, 2019 Report Share Posted February 16, 2019 This is going to get into the weeds a little bit. EGR should not have much of an effect on either CO or HC emissions. EGR is used to limit NOx (nitrogen oxide) emissions. The main cause of high CO is too rich, too much fuel, not enough oxygen to burn all the carbon in the gasoline completely. The main cause of high HC (unburnt gasoline) is a condition called lean misfire. There is simply not any gasoline vapors by the spark plug, so when the spark happens, nothing burns. Nitrogen Oxide emissions are caused by high cylinder temperatures during combustion after the spark plug fires. If you can remember gas laws from high school chemistry, high temperatures in a gas mean high pressure. For an engine to make a certain amount of horsepower at a given RPM, it has to have a set amount of torque, or in other words, a set amount of cylinder pressure. Adding EGR to the fuel air mix going into the engine cylinders reduces the temperature of combustion. This reduces the cylinder pressure. But you still need the same amount of power as before to maintain speed going down the road, so you open the throttle more to increase the cylinder pressure with EGR added to the fuel mxture. The cylinder pressure, and temperature basically stays the same, but with EGR, you are adding more fuel and air mixture (Lower Vacuum) to get the same power as before. Quote Link to comment
Velict Posted February 16, 2019 Author Report Share Posted February 16, 2019 Good info, thanks a lot. With this I guess you gotta be damn careful running that lean lol. Quote Link to comment
Velict Posted February 16, 2019 Author Report Share Posted February 16, 2019 (edited) 9 minutes ago, DanielC said: For an engine to make a certain amount of horsepower at a given RPM, it has to have a set amount of torque, or in other words, a set amount of cylinder pressure. Adding EGR to the fuel air mix going into the engine cylinders reduces the temperature of combustion. This reduces the cylinder pressure. But you still need the same amount of power as before to maintain speed going down the road, so you open the throttle more to increase the cylinder pressure with EGR added to the fuel mxture. The cylinder pressure, and temperature basically stays the same, but with EGR, you are adding more fuel and air mixture (Lower Vacuum) to get the same power as before. Yes that's what I got from it too, but I don't even know if any inspections test for NOx, they all test for HC if and CO if i'm not mistaken. It seems from the wikipedia page that I am reading that only 196 places within certain prefectures actually perform NOx testing for very specific levels.https://en.wikipedia.org/wiki/Emission_standard#Japan Edited February 16, 2019 by Velict Quote Link to comment
datzenmike Posted February 16, 2019 Report Share Posted February 16, 2019 Well, where are you? California is the most strict for testing. What year is your Sunny? it may be exempt from testing. Quote Link to comment
DanielC Posted February 16, 2019 Report Share Posted February 16, 2019 It is hard to test for high NOx, because you need to put a load on the engine to get the cylinder pressures high enough to make NOx. Quote Link to comment
Velict Posted February 16, 2019 Author Report Share Posted February 16, 2019 I am exempt in the states from emissions, but I'm military and travel to quite a few places. That's how I was able to import my Sunny to begin with. But if I go back to Japan, or get stationed in Hawaii (which overrides other states regulations) I may run into some bogus problems. Quote Link to comment
datzenmike Posted February 17, 2019 Report Share Posted February 17, 2019 What year? The allowable limits are probably high anyways. You only have to pass what it came equipped with. Quote Link to comment
Velict Posted February 17, 2019 Author Report Share Posted February 17, 2019 1987 Quote Link to comment
datzenmike Posted February 17, 2019 Report Share Posted February 17, 2019 So this would only apply if you move with the truck out of the country. Remove and keep anything you take off. Put what ever you like on for carbs and exhaust.... winning If you move to Japan..... put the pollution controls all back on..... winning. Quote Link to comment
Velict Posted February 17, 2019 Author Report Share Posted February 17, 2019 (edited) You know, I actually found something quite interesting. I did some really deep research; which for the Ratsun community would be common knowledge! The Weber 32/36 has peak performance around 115 HP, while the Weber 38 is 'bout 150. After taking that into consideration, I've chosen to go with the Weber32/36 because it is a very simple and clean set up with all of the goodies for regular driving applications; Such as electric choke, vacuum advance ports and WOW EGR! Here is the link to where I found that information.https://tercel4wd.com/forums/viewtopic.php?t=9409http://www.clutchkitcenter.com/media/images/weber/K675.pdf Edited February 17, 2019 by Velict Quote Link to comment
datzenmike Posted February 17, 2019 Report Share Posted February 17, 2019 I know it has a ported vacuum for ignition advance. Don't know about a separate one for EGR. What engine??? Quote Link to comment
Velict Posted February 17, 2019 Author Report Share Posted February 17, 2019 A12. I'm about to send Weber an email. Quote Link to comment
Velict Posted February 17, 2019 Author Report Share Posted February 17, 2019 3 minutes ago, datzenmike said: I know it has a ported vacuum for ignition advance. Don't know about a separate one for EGR. Click the second link in my last comment. It shows an egr port. Quote Link to comment
datzenmike Posted February 17, 2019 Report Share Posted February 17, 2019 Must be something new from Weber. Never seen it mentioned before but most people don't use it, so maybe this is why. 32/36 is way too big for a 1.2 liter engine. Stock 1200 is 20/28mm. You're going to run a Weber that has a larger primary that the stock secondary? Never, never never over carb your engine. http://datsun1200.com/modules/mediawiki/index.php?title=Carburetor_Sizing Quote Link to comment
Velict Posted February 18, 2019 Author Report Share Posted February 18, 2019 Oh, that's not a problem. Venturi sizes can be managed with replacement kits for dirt cheap. Many sizes available.http://datsun1200.com/modules/mediawiki/index.php?title=Weber_32/36_Carburetor Quote Link to comment
datzenmike Posted February 18, 2019 Report Share Posted February 18, 2019 Well good luck then. Quote Link to comment
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.