348/409 with Corvette-type Fuel Injection
- Thread starter threeimpalas
- Start date
He has Z11 heads that cost over ten grand with self destructing valve seats on the first run of the engine too. Just view the 1961 Biscayne project thread and you can see pictures and read all about them.
If you do the work yourself and don't buy all aftermarket components (ie; wire harness) you could do it for a lot less cost.
It also would look out of place if trying to go for a 60s vibe. Far too modern.
The Corvette fuel injection plenum feeds directly to the runners. An adapter on top of a 2x4 intake wouldn't work.
The only way the PCM and the knock sensors can be removed is to use a throttle body type injection system. The PCM tells the injectors when to fire and controls timing. The knock sensors tell the PCM when the engine is timed poorly.
I do whole heartly agree this is a hugely modern look.
Yes, a ECM/PCM is required. A TBI requires an ECM as well.
Depending upon the ECM system used, knock sensors may or may not be necessary. I'm not sure if the GM LSx systems can be tuned to ignore them or not. Some things can be tuned out and ignored (rear O2 sensors, MAF), while some can't (cam and crank position sensors).
Most of the aftermarket systems (Accel DFI, BigStuff III, MegaSquirt, etc) do not require knock sensors, but do have the capability to add them if the ability to pull timing due to knock is desired.
The main reason I think I would go with the 80 pound injectors is I'm punching out the 348 to a 434 and would like to go with forced induction at some point. Could easily use 65 pound injectors with a 434. This might be an old concern but I've heard a lower pressure injector can wear out quickly if it is asked to stay open longer. It may not be the case any more but it is a consideration I've heard.
I would think some efficiency would be lost if the rear O2 sensors are removed, how would air fuel ratio be measured?
One day, before my 5 year old is old enough to drive, I hope to have some real experience driving this thing rather than keystrokes on the keyboard.
I would think some efficiency would be lost if the rear O2 sensors are removed, how would air fuel ratio be measured?
One day, before my 5 year old is old enough to drive, I hope to have some real experience driving this thing rather than keystrokes on the keyboard.
You would keep the front O2 sensors to measure air/fuel. The rear O2's that you tune out are just to measure catalytic convertor efficiency.
I have a crank trigger now on my 409 and you do not need a cam signal generator unless you are running timed sequential fuel injection. you can run batch fired injection on the crank trigger or distributor alone. And as to the knock sensor, it is not required or recommended in any after market system. The knock sensor has to be tuned for that drive train in that type of car or it could be fooled into retarding timing because a vibration somewhere in the car. I have a knock sensor connector in my Holley HP harness but they specifically told me NOT to use it unless we properly tuned the sensor to the car. Waste of time. The wide band O2 sensor and the map sensor and the self learning capacity of the ecm maintain proper air fuel ratios much better than having a knock sensor in an "old technology" system retard the timing.
The newest generation of EFI that is on the market (last 6 months especially) is light years ahead of what was done before. As to Fuel Injector size, it relates more to HP than boost or displacement. I had 55# injectors in my 409 and they were MUCH too large, would flood the engine at idle because they would not "throttle down" have 36# injectors now (making 455hp/461ft/lb torque) and they say I'm good to about 600hp with these injectors. and the motor is happy now. There are injector sizing calculators all over the net so if you are looking for a set of 55s I have a brand new set of Accel 55# injectors Ill sell cheap. you are better off slightly undersizing than oversizing.
Big Jim
The newest generation of EFI that is on the market (last 6 months especially) is light years ahead of what was done before. As to Fuel Injector size, it relates more to HP than boost or displacement. I had 55# injectors in my 409 and they were MUCH too large, would flood the engine at idle because they would not "throttle down" have 36# injectors now (making 455hp/461ft/lb torque) and they say I'm good to about 600hp with these injectors. and the motor is happy now. There are injector sizing calculators all over the net so if you are looking for a set of 55s I have a brand new set of Accel 55# injectors Ill sell cheap. you are better off slightly undersizing than oversizing.
Big Jim
Big Jim - Thanks for the info! If I were closer to even starting the engine rebuild, I might consider the injectors. For now, I have to day dream and hold off. I'm sure the LS style system is a sequential fuel injection.
My main goal in the LS style ignition system is to have the 80 - 100,000 volts at each plug.
There is definitely more research to be done on my part once I get closer.
Thanks again!
My main goal in the LS style ignition system is to have the 80 - 100,000 volts at each plug.
There is definitely more research to be done on my part once I get closer.
Thanks again!