nitrous thread #865,382

[Hack]

Yes, I did a search. Try doing a search on nitrous and see how many threads come up, most of which have nothing to do with nitrous what so ever. After scanning dozens of threads, and hundreds of posts I still do not feel as though I have a complete answer to my question.

What specifically are the problem areas in the SHO V-6 in regards to nitrous.

1.I am aware of "puddling" or fallout in the runners on wet systems. 2.I am aware that the stock pistons are not stout enough to take large doses. 3.I also know that you should retard the timing on larger doses.

My responses to those issues are this;

1. I want to do a direct port system.
2. I already ordered new "nitrous ready" pistons.
3. I have a TwEECer R/T

What other things should I be concerned about? I am also aware that the fuel rail sits under the intake, and will make the direct port system difficult to fit. SHOnut phenolic intake spacers can cure that. My main concern is the internals of the motor. Also, it is a later 3.2 block, rods, and crank, so the wrist pins are the larger 22mm variety.

 

[olympic]

The biggest no-no is a "wet" nitrous kit, meaning fuel and nitrous are injected into the TB and allowed to find their own way to the cylinders. This causes the fuel puddling you mentioned and can run the engine lean or even cause an explosion.

The engine internals can take quite a bit in stock form as long as detonation is avoided and the A/F ratio is monitored closely. Since you'll be upgrading the pistons then there shouldn't be anything to worry about.

With a dry nitrous kit, the biggest concern is maxing out the stock fuel system(pump and/or injectors). That generally happens around the 100-120hp shot mark.

A direct port injection kit is the ultimate setup. You'll definitely need a larger fuel pump but that's about it. Like any big HP mod, careful and systematic dyno tuning will be a must. Start small and work your way up while watching for problems. There are SHO's out there running over 500hp on the stock crank and rods so this engine can definitely take the punishment.

 

[Hack]

Noted. The amount of nitrous I intend to run will definately require fuel system upgrades.

 

[SHO92]

Doug Lewis had a direct port system on one of his cars a few years ago, 1998 maybe. You might want to try calling him and see if he'll let you in on anything he found out. I remember reading about someone, maybe him, putting the fittings on the flat spots on the tops of the long runners(I think it is the long ones). They found out though, that although it was a very convienient place to put them, it was too far away from the valves. If you look around on shotimes, you might find a picture of Dougs setup. There used to be a picture of the mainfold on the car, and one of him holding the manifold when he was trying to sell it. He might even still have it for sale!

 

[Off Road SHO]

Here is a pic of how one SHO race car was set up.

The offroad car is a mid engined SHO powered, nitrous injected, two seater.

He's in our AZ SHO Club, names Troy, so if you PM me your phone number I can pass it along to him.

Tom

 

[Hack]

I have been doing some initial calculations regarding injector size. Some of this is theoretical mind you, as the engine is not yet built. I am using a rough estimate of 300 chp. It has every bolt on available, worked over heads, stage 2 cams, 3.26L and 10.5:1 cr.

Using the formula provided in the May '04 issue of Grassroots Motorsports, I would need 35 lb/hr injectors while running naturally aspirated.

Fuel injector size lbs/hr= Max hp x BSFC
--------------
# of cyls./ 0.8

BSFC= Brake Specific Fuel Consumption. THey say naturally aspirated engines usually range from 0.45 to 0.55. I ran the equation with 0.55 because I would rather err on the side of being rich than lean.

That calculation is based off an 80% duty cycle (hence the 0.8). I know that Alberto has said that the 80% max duty cycle is a myth, but again I would prefer to be on the safe side. I don't want several thousand dollars worth of fresh engine to detonate itself to death.

All that being said, I am hoping to eventually achieve a 200 hp gain with the nitrous.(Yes, I will work my way up to that point and not just jump in full tilt.) Using the same equation, I would need 58 lb/hr injectors(or whatever size is available that is close to that amount).
*edit* I just read my own link (see below) and it appears as though the NOSzle system also delivers extra fuel. So in theory, I could use the smaller injectors.

OK, here are my questions.

1. Does nitrous effect the BSFC?
2. If these calculations are correct, would the 58 lb/hr injectors absolutely drown the motor when off the bottle?
3. With those injectors (58s) wouldn't I need a 255 lph fuel pump to supply enough fuel? Would a quality aftermarket fuel pressure regulator keep things running correctly when N/A?
4. I am completely wrong in my thinking?

Also, I take it that this is the motor that you mentioned Bill?

Jason (yamahasho) got it for me.

As far as what I want to do, here is a link;
NOSzle system
It will probably require raising the intake manifold using SHOnut phenolic spacers, but will leave everything clean in appearance. And no, I don't just want them because they match my car.

Tom, I will send you a contact number shortly. Thanks!

 

[SHO--ripper]

I bet that 2 seater is pretty quick

 

[freeze]

58lb. injectors are too big. 36lb. will support the 200 extra hp. you want.

 

[freeze]

58lb. is too big, if you are wanting to gain 200 hp. over stock then 36 lb. injectors are fine.

 

[SHO92]

Glen, thats the intake I was refering to. And you can also see the flat spots I was refering to, but it looks like the Buggy pic that Tom posted is using the flat spots, so maybe with some proper tuning, it would work. The Noszle looks really cool, it definitely adds a lot of extra height though, hopefully the phenolic spacer will be enough.