Thread: ThrottleBody Nitrous Plate vs DirectPort

About to start the 1/4 mile build for my 1996 G20t 5 speed. I'm planning a dual stage Zex nitrous setup with a few addons. Stage 1 will be 75 shot @ WOT and stage 2 will be 150 shot on a window switch. I was wondering If anyone has tried a TB plate setup for your wet kit. I was just going to design and have made a custom plate with a port for the nitrous jet. Possibly angled into the plenum. I'm choosing this method because it gives the best likelihood of even distribution without going through the hassle of direct port. Opinions/Experiences?

Alternately, while direct port is a bit of a hassle ... How easy is it to tap the manifold and what are the best places to tap? Keep in mind it's a low-port motor. Pictures of your low-port direct injected nitrous setups would be great.

Appreciate the help. I've spent a lot of time perusing the forum for nitrous info but if I missed something that answers my questions then just link me on over and I'll quit clogging the forum, haha. Thanks!

direct port wet. jet it just a tad bit rich

A lot of extra money in jets and whatnot however. Also, would still need to know where and how you guys are tapping the mani.
With the regular airflow coming through the TB and being dispersed amongst the runners a TB plate setup makes life a lot easier. Just like every I4 motor we can expect cyl 1 to be getting the most and cyl 4 to be getting the least but that's simply the way the intake manifold is designed on 99% of I4 motors. However, this is where an angled injector can help offset that difference.
Also, I'll be using a Zex setup which ports the fuel directly into the nitrous path.
As far as richness to reduce the risk of detonation (which I assume was your point in saying "jet it just a tad bit rich") I'll be taking care of that by adding my own mix to raise octane levels. Besides the obvious slight richness designed into off the shelf wet nitrous systems anyways.

i mean if you can come up with a direct bolt in nitrous plate between the tb and intake mani, then id do that. it seems like a cool idea plus im sure you could prolly make some money off of them

Well I was simply going to design one just for me but if there's be interest on the forum then a group buy might be doable after I run my setup for a bit.
If you think about it, carb motors run nitrous plates directly under the carb. The carb also acts as your throttle body. Distribution of the nitrous from there is handled by the regular manifolds air flow characteristics.
I've ran similar setups in the past. It saves alot of time, money, and frustration vs a direct port setup on a manifold that isn't designed with spare bosses.
I was mostly curious if anyone has tried it on a SR20 yet. Manifold design plays a big part and I'm not terribly impressed with the oem intake mani. It seems to be designed like every other 4 cyl manifold ... poorly ... lol.
However, if it flows nice and evenly then the TB spacer nitrous setup will work pretty well.

Exactly what difference do you see in your plate idea, vs simply plumbing a nozzle into the intake right in front of the tb? You have to use a plate on a carb, there's no intake to plumb into. If you want even distribution of your nitrous, and more importantly your fuel, direct port is the ONLY way.

The only real reason not to plump directly in front of the TB is so that you dont freeze up the TB, haha.
Air entering the motor gets distributed evenly (as possibly) by the design of the intake manifold. It isn't perfect on inline motors but if the distribution was THAT wildly off then each cylinder would have drastically different AFRs which simply isn't the case.
Direct port is only an improvement due to higher velocity and lower temp strictly due to proximity to the valves.
The throttle body plate idea isn't a concern of flow or distribution really. It's a question of has it been done. Not to mention I haven't received a reply with direct port directions yet ...
Fuel distribution when your farther away from the valve is simply a question of atomization and the vapor qualities of the fuel. The toluene mix I run improves the vapor qualities and a well designed fuel jet like the one combined with the nitrous jet in the Zex wet kits should handle the atomization. So long as it isn't over fueled to the point it pools in the plenum.

Direct port ftw like aaronnx said...

If the runners are too thin to drill and tap for nozzles Nx express sells aluminum bungs you can have welded on for some thickness before drilling and tapping....no ones gonna have direct directions on how to setup direct port by make or model...you just gotta do it

Direct port injection is superior to TB injection for a few reasons.
The main reason being so you get an equal amount of added oxygen to each cylinder. Manifold designs are not perfect. Different cylinders get different amounts of air. Adjacent cylinders can also steal air from each other during induction strokes.
While modern manifolds are designed to mitigate these problems, they cannot be expected to have anything approaching equal flow to all cylinders when a comparatively dense liquid is sprayed into them.
For the same reason we don't have TB fuel injectors anymore, you don't want a TB injector for nitrous oxide. The much heavier liquid will behave quite differently than the incoming air, tending to favor one particular cylinder much more than any other.