420a turbo questions

[bpage020602]

Ok I got a 96 eclipse rs with the 420a.. I got a kit off someone that had a 4g63 and totaled it by a hit in the rear. I had to get a different manifold for the 420a but the rest will work. I changed fuel pump and got 450cc injectors. Its a 16g turbo, intercooler and all the pipes. A hks turbo timer, a greddy protec-B, and a S-AFC. along with boost gauge and air/fuel ratio gauge.. Now i know running over 8 psi with total stock motor is a big no-no... but without changing rods and pistons whats the most i can run with above mods..still only 8psi.. ya i know i plan on doing some internal mods, but not yet.. cars been out for few weeks and want to get it back on the rode for awhile before i really take it all apart.... I just want to know A----whats the most I can boost with no real internal upgrades and B-----What internals will i have to change other then rods and pistons to run MAX boost which will be*******. 32psi or what...

 

[VelocitàPaola]

A. 8-10psi
B. Rods and pistons should do it... although most people opt to get new bearings, oil and water pumps, etc. while they're down there. Plus there's always gaskets and sealants that will need to be replaced when you tear down the bottom end.

 

[bpage020602]

ok so ill run 8psi untill i change rods and pistons... and ya ill changes the pumps and the other little things at the same time...

So there is no limit to boost untill fuel cut rite... think valves will hold up...

 

[VelocitàPaola]

Um... fuel cut for N/T cars happens at 1psi. You'll need and FCD or missing link to be able to run any boost at all. Beyond that, you can boost infinitely, so long as your fuel system is up to the task, and the bottom end can take the beating.

If you don't have an FCD, PM me, I'm in the process of making another batch for 2G N/T members.

 

[bpage020602]

what is a fcd

 

[VelocitàPaola]

FCD=Fuel Cut Defender... here's how it works:

The MAP sensor reads engine vacuum on a linear voltage scale. This means that the MAP sensor will send a 0.3V (not an actual number... just used for demonstrative purposes) to the ECU when it is seeing 30inHg of vacuum. It'll read something like 4.7V at 0inHg and 4.8V at 1psi of boost. When the ECU sees a signal of 4.8V for more than two seconds, it'll cut signal to the fuel injetors.

All in all, the FCD is a pretty passive device. It sits inline between the MAP and ECU and transmits signals between them. When the MAP sensor starts sending a signal of 4.8V or above, though, it'll intercept those signals, and modify them to 4.7V. FCDs are basically voltage clamps with a few special features. For instance, they shouldn't add much resistance to the MAP output signal, and they should have a sharp cutoff at the specificed voltage threshold.

I'm not a fan of the zener diode/pot/transistor FCDs for the reason that they lack a few of those crucial features.