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Ditched turbo ZX ECU for SDS :-)

419 Views 10 Replies 10 Participants Last post by  2slo4u
I'm working on a customers 77 280Z that I swaped in a spearco intercooled ZXT engine last year. He wanted to use the stock ZXT electronics even though I warned him not to. Well after a year of fighting with it and it's problems (he lives in another state) and trying a RRFPR etc to get it to run good with more than stock boost, he gave in and let me rip all that garbage out.

He didn't want to spend the money to fabricate a crank trigger so I set it up with a fuel only SDS system, some 440cc/min injectors, removed the RRFPR, used a stock 77 single pickup dizzy and an MSD BTM ignition box. I set it up with 40 deg total timing without vac, ran the vacuum advance off the TB and set the BTM to pull out 3/4ths of a deg per pound of boost.

After about 20-30 minutes of tweaking the fuel curve from some base sample maps at the SDS site, this car runs so much better it's unreal. The off boost power is fantastic, the drivability is MUCH better than any ZXT ECU'd car I've ever driven, strong throttle responce and has great power at 13PSI with no detonation using the stock turbo/engine. Of course in hot weather he may have to run more boost retard, but that is there at the twist of a knob, instead of having to retard the WHOLE curve with the stock ZXT system manually turning the dizzy which kills all the off boost power etc.

I'm convinced, the stock EFI system doesn't have nearly enough ignition timing dialed in for off boost use and since it doesn't use a map sensor, it can't know when to do that (or pull it out) if it wanted to. Anyone who argues this ZXT stuff works even decent, has never seen the difference using a setup like this makes.

I don't think I'll ever let someone make the mistake this guy did using the stock ZXT ECU again. If anyone here is doing this swap, --SERIOUSLY-- consider selling all that crap on ebay to at least partially fund a setup like I used on this guys car or use the stock early EFI with a BTM box and bigger injectors! I do love how easy the SDS system is to setup and adjust, I had the car running great in about 20-30 minutes driving it less than 10 miles. This is a no brainer in my book.

BTW here's some shots of his car, will have the most recent to upload this weekend. He's got a super nice turbo Z

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i feel it. oh boy...

now if i could just convince the wife it's a good investment...
hey steve, what TB are you using and what TPS?
Nice post with good information and pictures. Where is your shop located?
Awesome post...!
You know I always hate to sound like a sales man on this thing (I am). Standalone is always one of the first things I recomend when anyone is looking for safe reliable horsepower gains. Just like you years ago I was way sold on how much better things are when you dump a caveman era AFM in favor of a MAP. Its hard to explain to a non-beliver how much better a Z runs with a EFI system. Good post, nice work.

Alex C
Man that's one **** of a long intake pipe lol

I'm gonna run a Megasquirt Fuel n Spark on mine. So Steve, you reccomend a 77 dist. for this kinda project? I just happen to have a 77 distributor on my 77 280Z that Im puttin the motor in. :-D
It's using a stock TB and a TPS off a 300ZX automatic. Today did some more tuning, turned the boost up a touch to 14PSI and it's FAST! :) I think it's about to rip the clutch up now!

I've seen these spearco intercoolers for sale for around $600. This IC is unreal how good it works, WAY better than the rice boy tube and fin type, even ones that fill the whole grill area.

After driving this car and another that the customer did himself with ZXT ECU and a much bigger T3/T4 turbo with a giant tube and fin intercooler, this T3 car would KILL his and spools up twice as fast to boot.

I guess my point is why spend the money doing loads of internal engine mods and a T3/T4 turbo etc and then be cheap on the electronics?
Would Megasquirt give the same resuilt?


i hope so :(
Guess I'd better dump the 85turbo zx ecu, coil, crank sensor, and mass airflow sensor I've transplanted into my 81turbo zx, ha, ha! Nahhh.

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