So I've recently purchased a 87 TII. Its a s4 with s5 internals with a hybrid turbo. Hybrid stock hot side and around a to4b cold side with bigger wheel. Running of 550 and 750 eiyh a fd fuel pump. The car is currently on stock ecu, but it came with a megasquirt. I was planning tune the megasquirt, but I've deceided it would be a waste of money if I just tune it now. I figure, I might as well upgrade a little before the tune.

So for upgrade list I've got in mind is

Fmic
Bigger injectors (not quite sure what size. Suggestion would be greatly apreciated!)
Walbro 255

That's what I have in mind so far. I was just wondering does anyone else have any suggestions or recomendations? Thanks!

 

Don't run a hybrid turbo on the stock ECU. And depending on the size of the compressor wheel, your injector combo will max out quickly. As it stands now, you're going to blow the engine unless you keep the boost way down (stock-like levels). Get the megasquirt setup and use larger injectors such as 4 x 720/750s or even larger on the secondaries. The biggest factor working against you will be the aggressive timing on the stock ECU, and there is no piggyback that you can use to control it.

 

Well right now, I understand factory ecu has boost limit, and fuel cut kicks in at 7-8.6 (which I never hit). Yes, I am planning to set it up with the megasquirt, but I bought it used, and the previous owner had it tuned for 720/1680. So the car won't be able to run on it. To be more specific, I was just wondering what size injector and fuel pump do you guys suggest me getting before I head in to get it tuned with the megasquirt. I see no reason why to tune it right now as it is if I am planning to upgrade in the future anyways.

 

Here's the thing: You cannot tune the stock ECU. The best you can do is use a piggyback like the S-AFC but that only allows rough control over the fuel curve. With an upgraded turbo, you WILL run lean at around 3800 RPM and that's where the engine will pop.

If you are going to Megasquirt the car, then just do it. Whatever "tuned for 720/1600CC injectors" means, it's irrelevant. You can easily change the injector settings to suite any injectors you want and it will have to be tuned for your car anyway.

 

I guess disregard my previous post? Basically I am wondering if I should/ what injecotrs and fuel pump should I upgrade to with this current (will be replacing the stock ecu with the megasquirt) set up of mine?