The deal - I have a nitrous plate that was custom made to fit under a Nikki.

The question - Do I mount it under the carb or under the stock phenolic spacer?

The issues and more questions - The holes in the plate dont exactly line up with the throttle body section of the carb. They are all a little bit off in 1 direction. I cant remember which direction but that shouldnt matter I dont think. Previously I installed this and noticed my idle was impaired somewhat. I also noticed my throttle response was a bit off as well. Not sure if I installed it in the wrong place (above question) or if the holes being a bit off is what caused this. So my main question is this - Would it hinder air flow worse if the hole was a bit too big compared to the throttle body? I ask this because this seems about the only way to fix this other than hogging out the mounting holes which could work also. Really I need some advice on the best way to do this.

I previously thought about selling the plate and running 2 foggers but the extra cost for setting all that up would hinder other areas such as buying more safety equipment (blow down tube, gauge, etc).

Thanks for any input.

-IanS

 

Picture - Obviously they copied the intake manifold.

 

Hmm... if you mounted it directly under the carb, there's a chance that the secondary plates might make contact with the rail. And I would assume that the channeled side would face down to match the manifold. So I would mount it between the stock spacer and the manifold with gaskets on either side.

Now your alignment problem is, well... a problem. I would slot the mounting holes and line it up correctly.

I'm not gonna go into the whole "is this a good idea" aspect since I really know nothing about nitrous in carb applications. Let us know how it works out

 

Yeah I would really like to get this to work as it would be less expensive overall to tune it and I have had everything hooked up and working with this previously. Last time it was installed I didnt think about fuel pressure being at 3 when the system is set up for 7 as far as fuel jetting goes so it was running nitrous rich (fuel lean) and after MUCH detonation trying to figure out the issue I ended up cracking 2 apex seals. I didnt know this until I took the "good running" engine apart to port it and upgrade some other areas as well. Even with the "little 50 shot" running and detonating all to hell it still gave a real nice kick in the pants. I am thinking that I now have close to the same power without nitrous as before with nitrous so this should be a pretty good time.

 

Were you trying to run a dry shot??

 

No it was wet, a carb kit. With the jet sizing recommendations from the instructions it was assuming the normal 7psi fuel pressure and I was running only 3 with my Nikki so less pressure = less fuel coming into engine. Basically, I just needed to do some easy math and go to a larger fuel jet with the nitrous jet I was using.

 

Oh okay, was wondering there for a second. Time for a wideband. Gotta be worth not blowing up another motor.

 

Thinking about this more I believe I installed it under the phenolic spacer previously but upside down as looking at the spray bars themselves if I were to put the 2 machined grooves together the holes in the spray bar would be pointing up. Maybe I just need to hog out the holes and spin the spray bars around so they point in the right direction. Im starting to get excited about this again.

Thinking more I may need to pick up a different/better heat shield since this would be underneath the stock one.

Anyone willing to post up a pic of their RE-Speed heat shield installed under a Nikki? That way I can see how much clearance I would have.

 

Here you go, this is the RESPEED heat shield with a stock intake manifold

 

Bad ***. Plenty of room.

 

Don't let the "nay sayers" get you down. I have ran nitrous on bikes, trucks, cars, even rental cars!!!!

Having said that, make sure your fuel system is up to snuff. In an ideal world, I would like to see you run a separate fuel line and pump and run the system at the designed 7 PSI. You could even run a small tank in your engine compartment with a holley Red fuel pump.

MAKE sure you either have a fuel pressure gage or a "hobbs" pressure switch that shuts off the nitrous system if the pressure goes low.

It makes me wonder if the fuel part of the nitrous kit will atomize and work right with 3 psi???? I know you can run a bigger jet, but hmmmm.... I wonder.

50HP will be fun, but some guys over on the "no-pistons" site have run 250 shots and the engines stay together.

Have fun, but use your head!!!

 

I also thought that I could "T" off the fuel supply line before my 3 PSI regulator and put in a 7PSI regulator (I already own a 7 psi one as I bought the wrong one) for the nitrous part. My thinking here is it should have plenty of flow to keep the carb full since I will only be spraying 1 fuel jet for the nitrous side (which will be a very small orifice as you know).

Anyone have any thoughts on this idea?

 

looks like someone beat me to answering your question.

I don't think that I would be much help with the nitrous questions as I've never played around with it.

 

The spray bar shouldnt effect your idle. Like some others have said, Its always best to utilize a dedicated fuel system with NOS.

 

So then if I should run a dedicated fuel system to run the nitrous what size fuel line should I run to supply my < .050 single fuel jet? Thats big enough to run a ~140 shot. I honestly dont plan on running anything more than 100 and thats on the extreme side. I plan on starting with 50 and going to possibly 75.

 

IF you had a large enough fuel pump like a holley blue or equivelent, then I would have NO PROBLEM running two regulators. One for the carb and one for the nitrous.

I would not run anything smaller than 3/8 tubing. If you had adequate pumping, then 3/8 would be sufficient for both since your total HP demand should never exceed 250 HP.

 

http://www.summitracing.com/parts/CRT-P4594/

Thats the fuel pump I currently have. 72 GPH and 8 PSI. Would this along with 3/8 fuel line be enough? The Holley Blue is rated at 110 GPH and 14 PSI. I used to have the Holley Red and it ate **** after 3 months and hung extremely low (might be the reason it went bad).

 

You should be OK. I would start at 50 HP and see how that goes. I would also install a fuel pressure gage so you can keep an eye on the pressure.

Also I always use a Hobbs pressure switch. This switch will shutdown the nitrous system automatically if the pressure runs too low.

http://www.ebay.com/itm/NEW-HOBBS-PR...item2a1210dfa2

 

I ran a single regulator for my carb and nitrous. The jets were sized accordingly using a chart someone reffered me to on another website. Check post # 12 in this link:

https://www.rx7club.com/showthread.p...hlight=nitrous

 

Do you still run the nitrous??

 

No. The new chassis / body is getting painted by myself so it's taking fooorever to get it close to perfect... but I did pick up a full V8 fogger kit with a giant assortment of jets so I will be playing again soon enough.