*Update below, engine blew up w/ pics**

Hello all,

I don't own an LS1 but there are only a handful of posts about nitrous in the Toyota/Lexus forums. Seems like a much more developed and not-so-scared crowd here.

I have a SC300 with the stock 2JZ-GE and 5 speed. Engine has 160K miles on it.

Here are my components:
Zex EFI wet kit w/ .067 N2O & .040 fuel jets
20lb bottle w/ NOS solenoid remote opener and 10lb heater (I want NANO).
Edelbrock FPSS (mine is either defective or this thing just sucks)
MSD Digital 6 Plus ignition
MSD Window RPM switch
Zex plugs
AEM UEGO
AEM FP gauge
TB microswitch to engage 6 degrees of timing retard from the MSD Digital 6+.
91 octane

I started with the lowest jet when I installed the system a couple months ago and worked up to 150. Fuel pressure has maintained at 40+ PSI throughout a 150 shot.

I'm using a 10lb NOS bottle heater which I've had nothing but trouble with (the thermostat wires constantly break off) and either want to go with an ARC mother bottle heater or NANO. NANO seems like it's own set of problems trying to find a fill station and changing out all my valves. I have two 20lb tanks. But heaters suck!

Here are some of my concerns and am wondering if you have any advice.

-The FPSS sucks. When it's set for the correct pressure there is continuity but the voltage cuts in and out constantly and the Zex box goes haywire. So I have to set it way past the PSI threshold which makes it useless. I don't know if it's defective or what. Any other recommendations for a FPSS? Maybe I should just order another brand if it exists.

-The time it takes to change the timing is longer than it takes for the N2O to spray therefore increasing detonation risks. It takes about 1/2 of a second or so before the timing retards 6 degrees. I found a solution from Wolstentech which is a timer relay that could delay the Zex NMU spray by 30ms to 1 second, but then every time I let off the gas the delay would start again. I'm at a loss for a solution to this problem. Maybe extending the N2O line would slightly help.

-I'm seeing some detonation on the plugs I believe. Here are some pictures attached. The #6 (by EGR) plug's porcelain cracked recently. It was either defective or heat/detonation caused it. I don't know and am trying to work it out with Zex. Any ideas?

-I had it dyno'd when I was running a 100HP jet and gained 77hp and 90tq.

Anyway, nitrous is fun and super expensive at $5/ lb. Getting a mother bottle is basically impossible in LA after that bust last year. I should have just gone turbo

 

NA-T man, NA-T. You can leave the spray though

 

Plug 1

Plug 2


PLug 5


PLug 6 (cracked)

 

This is a perfect example of why to buy a quality, higher-end product the first time.

 

I don't know much about Zex plugs but there is no way I would be using a plug like that. It looks projected tip and then it has 3 prongs which makes it worse.

 

Ouch! All the Zex hate. Their plugs are made in France by I assume is NGK. Can you recommend another plug model if you feel strongly about it? I am willing to try something good else. I saw the spark plug thread but I do not understand all of those numbers. What do you think about the condition of them? They were not inspected immediately after a run, and I know they should be. Also, those probably have 5000 miles of daily/N2O driving on them.

Thanks,

 

I can see that plug is gasket seat and when I look up all the Zex plugs, they are 14mm thread and .750 reach. To get a plug in the same range the stock # would be NGK 4091 and the part # is r5671a-7.

It is a 7 heat range plug which is cold enough for a 150 shot if your motor compression is somewhere around 10-10.5:1

 

i've seen nothing but problems out of zex units, mulitple boxes with the fpss making it cut off like that or it just not working all together. i would try to bypass the fpss and put a fuel pressure gauge in car if you want to be safe. i can only imagine what their plugs run like smh...

 

No way I'd run those plugs on a nitrous engine. non projected ngk is what you want.

 

Hey guys. Sad update. Intake backfired and engine is toast. #2 cylinder has no compression. Too bad as I've ran probably 10 bottles through this without issue.

I hit the pedal, heart some clicking and the power was abnormally strong and instantly saw a giant fireball come out of the hood. Car died, pulled over and intake piping was blown off and the air filter was charred. TB butterfly valve was folder over on each side.

Took the plugs out and they were black and soaked in gas. Compression in cylinders looked like this from front to back:
120
0
125
125
130
130

I honestly don't know what happened. I'm guessing I reached the shot limit for that manifold design and it pooled. I don't know and it bugs me because I don't want to be scared of the nitrous. The only change was retarding timing to 7 degrees when I went to the 150 shot and I'm wondering if that was too much and the timing got out of phase. I was running 140 shot at 6.5 degrees for a while.

Just ordered a replacement engine and will start ripping the old one apart. I might take the old one and beef it up for direct port.

Do you guys have any tips on what to specifically look for after I pull the head off? Obviously a melted piston or something will be enough, but I mean like other ideas to try and trace what happened.

 

I don't think it was a timing issue. I think your intake has poor flow design and can't flow fuel well. A spray bar like nitrous outlet recommended would probably be better since it would put the spray point further down in the intake.

Once you get the head off you will be able to see the carnage. Ive done the same thing you have and it ended up being 2 valves broken. So the bottom half was alright. Do a wet compression test and that will tell you if its the botom or top half.

 

When I cranked over on #2, I didn't hear it opening/closing or whatever it's doing. You know, the "rrr, rrow,, rr, row" sound, it just kept spinning but didn't make the noise all the other cylinders did. Sounds funny, but do you know what I mean? haha.

BTW is this what he's referring to?
http://img.photobucket.com/albums/v1...MVC-001F-2.jpg

 

Those plugs... lol

Does Zex sell those as nitrous plugs ? if so... WOW!

Also a 150 on your 4 banger is = to 300 shot on a LS1 .. is this astock motor?

A 300 shot would need more than -7* of timing taken out and that plug...sucks.

Good luck !

 

I'm going to switch out plugs with r5671a-7's.

It's actually an inline 6.

 

So you still ran it on those zex plugs and didn't use the plugs I told you? That's asking for it in itself.

 

Big update.

Pulled the old engine apart. Found the #2 cylinder had a broken valve shim on the intake side. The cam lobe had damage too and the underside of the valve, along with some scratches on top of the piston.

Any ideas on what causes this? Stuck valve? Worn out? Timing jumped? Intake backfired and pushed the valve down? The seat is stuck in there. Some of the metal got into the oil pan!

 

Something else I found: the custom throttle body microswitch mount was blocking the throttle from opening all the way. This may have not sent the WOT signal to the factory ECU and cut air/fuel. We came up with a little bracket on the side now instead of the actual TB pressing the switch.

 

I tried the ZEX plugs on a junkyard D series Honda with a dry 100 shot, made better power with NGK. I always used a J&S Safeguard on all my Japanese N2O motors, saved my motor more than once. You can dial in the knock sensor sensitivity, set the amount and aggressiveness of timing pull. Worked great for me.

 

It's a inline 6 like the supra minus the turbo and other components

 

3 years later…

On a side not those engines are super tough. They will take a 200 shot easy if setup properly. (trans is usually the issue)

You can set the base timing to say 15-18* base per the factory manual. Then install a micro switch running to the timing pins. Set that up with the nitrous and when you hit the switch, timing jumps down to 15-18* base and stays there.