Highest compression ratio with stock fuel injections

[280zdude]

Hey guys I have a 77 280z and I was wondering what is the highest compression ratio that can be run with the stock efi system? 
 

looked online there is a lot of information but nothing specific to the stock efi that I’ve seen. 

[Zed Head]

It depends on the fuel being used and the camshaft and how you plan to drive it.  Best to stay away from highest.

[280zdude]

On 1/25/2021 at 1:40 PM, Zed Head said:

It depends on the fuel being used and the camshaft and how you plan to drive it.  Best to stay away from highest.

Im thinking about stage 3 cam with a thinner head gasket.. and maybe flat pistons. But I want to know if the stock efi would be able to handle that 

[Patcon]

I don't believe the ECU will handle a stage 3 cam. I am not sure it will even handle a stage 2 cam. The EFI is very basic and doesn't handle any but the most mild changes. Increased compression normally needs increased fuel and the stock system would be able to provide it.

[Zed Head]

17 hours ago, 280zdude said:

Im thinking about stage 3 cam with a thinner head gasket.. and maybe flat pistons. But I want to know if the stock efi would be able to handle that 

"Handles" means different things to different people.  You could make probably make it run, for sure, but it would be probably have problems in certain areas, like idle or cruise if you tuned it for top end, or vice versa.

[siteunseen]

What do think about a potentiometer to add more fuel for a cam? I asked about this earlier but can't remember who or what the answers were. I have a pot knob on my'77 and can flood it out with fuel or starve it. I think it's a 7,500ohm volume knob from radio shack? I do know Schneider ask if it's efi or carbs when ordering so I know it's an issue. That maybe another advantage of hole #3 on the cam spocket from the beginning. Racer Brown's L motor chapter 13, FYI.

 

Edited January 29, 2021 by siteunseen

[madkaw]

Hole 3 significance ? Racer Brown? @siteunseen

You would have to trick the EFI to give more fuel . Also have to trick the ignition not to time in too much or kapowy . 
Probably one of the worst heads for this scenario - pistons go without saying . 
 

 

[siteunseen]

That's what the potentiometer does, trick the ecu to richen or lean the fuel/air mixture. The 3rd hole advances the the cam timing. 

It's just some drinking thinking I've pickled around with, you know stirring the pot a little more. I get bored...

[conedodger]

The L28 likes compression. Wakes it right up. The ecu does not like funky signal. My old website PlanetZ from the 90’s gave instructions on how to put NA electronics into a Turbo AFM. Can it be done? Sure. It runs like $^!#. Use FASTEFI or one of the other aftermarket EFI systems. 

[280zdude]

This is the camshaft description. I was thinking adding this and possibly a thinner head gasket and go from there.. 

 

but it seems like that even then would be too much? 

[Zed Head]

You're in California.  You might not pass the emissions test.  That's another "doesn't work with stock EFI" problem.  Emissions, smelly exhaust, running lean at high RPM, those are the things that have to be balanced, that people have problems with.

[280zdude]

On 1/29/2021 at 10:23 AM, Zed Head said:

You're in California.  You might not pass the emissions test.  That's another "doesn't work with stock EFI" problem.  Emissions, smelly exhaust, running lean at high RPM, those are the things that have to be balanced, that people have problems with.

At this point I don’t think I was going to anyways lol the whole egr  side of the intake is corroded