So i'm puttin together my engine for a carbureted 88' wagon. I have a fuel injected head and my current plan is to use the head as it is and use an electronic fuel pump and FPR. My question is what is the stock fuel pressure feeding the carb? My current plan is to get a Fuel Pressure Regulator that will regulate between 2 - 6 psi or so whatver is available on the market and guess and check varying the pressure til the fuel bowl fills to the correct level.
Also the -fe head does not have the EGR port drilled in it. I know the EGR system was used to reduce combustion temperatures to minimize NOx production. I'm wondering if the increased % of fuel/air mix due to the lack of EGR under full throttle conditions will raise the combustion temp's and pressures enough to cause knock. I can always retard the timing a bit to cover for this if it occurs, but has anybody done this before?
something like 6psi.
Carbs work with really low pressure, float opens the needle valve, too high of a pressure is a problem because the carbs will flood.
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I know the EGR system was used to reduce combustion temperatures to minimize NOx production.
Actually no, its used to circulate exhaust gas to the intake side, so it burns twice... get rid of it, block it off whatever, you dont need/want it. And it wont work like you say, because you're creating an intake leak when you port it to the intake manifold, carb wont work too well with that.
I realize that the Exhaust Gas Recirculation system is meant to recircluate exhaust gasses back into the intake for a second time. The reason they do this is that because the exhaust gasses won't burn again, they act as a mass that absorbs thermal energy in the combustion chamber and replaces air/fuel mix that would only add more energy.
The purpose of EGR is to reduce the combustion chamber temperatures so that NOx.....an unwanted pollutant that is dominantly formed at higher temp's/pressures...is not formed in large quantity
I realize for performance one generally does not want EGR...but it does effectivly reduce combustion temperatures..and as we know, very high combustion temperatures and pressures will create an envirement where knock can occur.
So my question would go to somebody that has removed their EGR system on their stock 4-af carb'd model and can tell me if they experience any problems with knock afterwords or if they had to retard their timing any.
Carbed 4A-Fs dont have the EGR, reason is, a carb doesnt work if you have a intake leak, an EGR would be a very big intake leak. It wouldnt meter fuel correctly, so you'd get massive knock and little to no performance. I'm saying once again, to lessen headaches, leave it out.
Your combustion temps arent gonna reach that high to the point where you'd get knock because of that.
Knocking in itself is also a very interesting thing, as not only temperatures, but fuel mixture and timing play a part with it.
Carbed 4A-Fs dont have the EGR, reason is, a carb doesnt work if you have a intake leak, an EGR would be a very big intake leak. It wouldnt meter fuel correctly, so you'd get massive knock and little to no performance. I'm saying once again, to lessen headaches, leave it out.
Your combustion temps arent gonna reach that high to the point where you'd get knock because of that.
Knocking in itself is also a very interesting thing, as not only temperatures, but fuel mixture and timing play a part with it.
I don't want to argue over this, but my 88' carb'd 4af does have EGR equipment on the car, there was functioning EGR on my previous engine that had the EGR port in the head, and my haynes manual also outlines the EGR system on the carb'd models and not on the EFI models.
FYI, the EGR is a very very controlled leak, thats why the EGR valve is very important. And the EGR is introduced past the throttle plates, so the exhaust gasses are not affecting the mixture of the air/fuel being metered thru the carb. Since the exhaust gasses dont' have any oxygen b/c its already been burned once, it sorta just waters down the incomming mixture instead of affecting the stochiometry of the mixture as an intake leak leaking fresh air would.
Yeah I dont want to argue about it either. I've never seen an EGR on a carbed 4A-F, maybe thats a US emissions thing... anyways, if your law doesnt require it, ditch it. Theres better ways to cool an intake charge down, but really you're not running high enough compression to need such.
something like 6psi.
Carbs work with really low pressure, float opens the needle valve, too high of a pressure is a problem because the carbs will flood.
Actually no, its used to circulate exhaust gas to the intake side, so it burns twice... get rid of it, block it off whatever, you dont need/want it. And it wont work like you say, because you're creating an intake leak when you port it to the intake manifold, carb wont work too well with that.
no, he's correct. the exhaust gasses that are recirc'd do not burn, they just take up space where air/fuel could burn. less combustion means less heat means lower chamber temps means lower NOx counts!
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'88 Corolla, AE92 SR-5, 7A-FE swap/GT-S suspension
'87 Corolla, AE82 FX-16, 4A-GZE swap (autocrosser)
'03 Tundra 4X4 Access Cab, (FX tow vehicle/Home Depot runner)
Modification: Changing something to what you thought it should have been from the start!
ok, sorry, i didn't realize you were from finland....yes it is a US emmissions requirement....but for a visual check..where they look for the emmissions equipment it will still be there...egr valve etc..but the port in the head they won't see isn't there. The manifold will still bolt to it, but the EGR valve connectes to a dead end is all.
So the finland models don't have EGR on the 4af so what is the timing your stock engine is set to? I'll assume that all the vacume advance and centrifugal advances are the same...so then what is your static timing? I'll reference to my Haynes manual when i get a chance.
Just to close this item. My manual says that the timing at idle, ie at full idle vaccume advance, the timing on a 4a-f should be at least 12 degrees BTDC...the later 1990+ 4a-fe engines were listed at least 10 degrees BTDC.
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