Floorman

yeah i think it lets you know where your at and where you want to go i dont get mad when a dodge is faster just want to know what he has done to it. now a ford and a duramax well thats another story.

HOHN

OK, I want to talk more about nitrous on the truck and learn from you guys.

Pre-CAC nitrous seems a little wasteful to me. Why not take advantage of the intercooler first, THEN cool it farther with the spray?

If excessive cooling is the problem, then I'd think that simply moving the nozzle out of the hat and down to the post-CAC pipe would do the trick and give you the best of both worlds.

It should be next to nothing to either drill and tap that pipe directly, or weld on a bung and go from there.

Also, you could orient the nozzle to spray towards the hat (parallel to the flow) instead of perpendicular to the flow, and this would improve velocity going into the hat, imo. It certainly wouldn't hurt. The only downside to this is that you have a nozzle hanging down into the pipe-- but the pipe's area is much more roomy than the intake horn, so I don't think this is much of an issue.

I've really started looking into building a nitrous system for my truck as an alternative to getting a bigger charger. My plan thus far is to just plumb it off a Hobbs-switch.

I'd set it to that the nitrous comes in at 32psi or so, and the WG is wide open by 35psi. Then, I'd just increase pill size until I'm starting to see boost creep, indicating that the WG is being overrun.

So here's my rudimentary system: bottle--> ss line--> solenoid--> nozzle.

I'd set up a remote bottle opener on the arming switch, and wire the solenoid off the Hobbs.

Anyone done something like this?

I don't have a ton of fuel, so I don't need a very big hit. I'm guessing something around 75hp will do the trick.

JH

signature600

I haven't played with it at all, but everyone I've talked to says the power is smoother, running pre-CAC, and everyone who switched from post-CAC to pre-CAC picked up some power....sometimes substantially!

Chris

Mike D

I would use a WOT switch along with a Hobbs. Unless you're going to keep the bottle in the bed of your truck, a remote bottle opener is a probably unnecessary. I would spend the money on an automatic bottle warmer instead.

HOHN

Do you know if anyone trying to find the middle ground, as I mentioned, or have they all gone completely from the hat to pre-CAC?

HOHN

In my case the WOT would be redundant, as I'm only going to hit the boost numbers in question if I'm at WOT.

As for the bottle warmer, I can see how that's important for consistency in bracket racing or whatever, but I don't see that as a necessity in my usage. The bottle would be used for such a short time, and with lots of time between uses that a bottle warmer isn't really that necessary.

Nitrous systems can have a LOT of features involved if you want them to, but on a diesel on the street, a nitrous system can be very simple and inexpensive.

Remember, I'm only trying to give my stock turbo a little longer legs-- not break any dyno records or get my truck into the 12s, or what have you.

Honestly, the most pressing concern I can see is the need to switch to a no-timing Smarty tune if I runthe squeeze, as the combination of Smarty timing and nitrous might make a casualty of my stock HG.

jh

signature600

Don't know...seems like everyone either sprays at the hat, or pre-CAC...unless they have one of those spray bars in there manifold!

Chris

XLR8R

Well Justin, that's a great idea to test out - however, I don't think the results would be very different, considering the intake charge's velocity and the relatively short extra distance from the pill to the combustion chamber.

I expect the post-CAC location to be of small, but consistent benefit. I think that the BSFC of the CTD is helped more by extra air than lower charge-air temps (yes I know that the two are not independent); the stock 3rd gen CAC is very efficient, especially when the A/C condenser is moved to provide unobstructed airflow.

Maintaining or accelerating intake charge flow velocities is not nearly as critical on a forced-induction engine as on a normally-aspirated design, so spraying the nitrous perpendicular to the flow path shouldn't be an impediment.

Why do you think the NO2 would be detrimental to your HG?

Mike D

I agree about the simple and inexpensive part, the title to this thread says it all...

What's the reason behind your boost setting for Hobbs?

Mike D

I have a question? What is the temperture of the air pre-CAC?

XLR8R

The '05 has generated over 350*F in the pre-CAC pipe at 48psi boost.

I designed the nitrous system control with a cascading relay scheme to give an initial "hit" to spool the turbo(s), then come back in again under heavy fueling when the extra air is really needed.

Mike D

So, where does the extra oxygen come from with the nitrous coming in pre-CAC?

Mike D

Just to clarify, I'm assuming by "air" you mean oxygen from the nitrous, right?

paulb

I used to think the same way, but it's not only the temp of the air, but the density. If you cool the air pre CAC, then the air in the CAC is more dense (I know, stating the obvious). The more dense air charge will radiate more BTU's of heat then a less dense charge. Let me put it this way. If you have a hot bolt, which cools it faster. Air or water? At some point of temp vs density, the temp will win, but with the temp differences that we have in our trucks the density appears to be more effective.

Paul

Mike D

OK, I'll ask Paul. Using the same jet, how much power did you gain going pre-CAC?