SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: electrowoman on February 05, 2009, 11:29:03 PM

Title: A nitrous question for seasoned professionals....
Post by: electrowoman on February 05, 2009, 11:29:03 PM

I've been thinking about using nitrous in my 460.  I have no experiance with it so I'm hoping you guys can answer a few questions for me.

1.  The engine is fresh, built well with forged pistons, eagle rods, edelbrock heads, 850 Holley, Hi vol fuel pump and a very stout valve train with stud girdle.  It runs around 61 MPH at 5000 to 5100 RPM's now.  I would like to try 100 to 150 HP shot.   Should this be a wet system for that HP range?  What do you think of the ZEX setup?

2.  Does nitrous really do any good in a boat??  What RPM increase would you think it would produce?

3.  What size bottle?  One or two?

4.  Roughly how long does a bottle last say 20# at 100 HP setting.  150?

5.  What does it cost to have one refilled and where do you have that done?

  This would be for a once in a while short burst operation, not running all day WOT.... 

  It's 2 degrees outside right now,  where oh where is summer?

  Thanks for the help in advance!

Title: Re: A nitrous question for seasoned professionals....
Post by: crewchief22 on February 06, 2009, 05:44:41 AM

Not a seasoned pro with N2o in boats but I do have some experience  ;D

The engine sounds like it has a very good base for nitrous, but the first thing I noticed was the exhaust logs.  A lot of the gains you could get from nitrous would be lost in the restricted exhaust system.  Getting a good set of TT headers might help get you more top end without the nitrous and help the nitrous be more effective.


Personally any system over about 50hp "Sneeky Pete" should have added fuel.

Title: Re: A nitrous question for seasoned professionals....
Post by: SLCKREG on February 06, 2009, 07:22:24 AM

Far from an expert here, but I wouldn't go to huge unless you knew how large(or small) your ring gap is. When I told my motor guy I was going to boost and or throw some nos ant my new deal, he opened the ring gap from .017 to .024

Title: Re: A nitrous question for seasoned professionals....
Post by: electrowoman on February 06, 2009, 11:48:16 AM

Those logs are off now.  We went with the long bolt logs port matched to the heads.  I would like
to see 65 MPH from the boat for short runs. 

Title: Re: A nitrous question for seasoned professionals....
Post by: beerjet on February 06, 2009, 06:14:06 PM

I'm gonna go with the consensus.
Ditch the logs first.

Another thing is that at 5k RPM , you should be going a little faster .
A freshened up pump might just drop your RPM's with the same or maybe more MPH.
One thing people always go around when lookin for MPH is the pump.
Make sure it's fresh and tight.

-beerjet-

Title: Re: A nitrous question for seasoned professionals....
Post by: BOOST on February 06, 2009, 07:06:02 PM

Ditch the nos bottles are for babys LOL ;)

Title: Re: A nitrous question for seasoned professionals....
Post by: electrowoman on February 06, 2009, 07:10:31 PM

The engine only has logs because I couldn't get the upward manifolds to clear the valve covers.
The tall covers were necessary because of the stud girdle.

I think I'll just scrap the bottle idea and do a more tuning.

The jet was rebuilt about 4 years ago but the impeller does have a couple nicks that I filed out.

Title: Re: A nitrous question for seasoned professionals....
Post by: IRRebel on February 06, 2009, 07:30:19 PM

Word of advice, from the old days. Not much experience with boats, but DITCH the manifolds and get headers, NOW!. The bigger the better where NOS is concerned. Nitrous oxide by itself does not burn. It is an oxidizer, that , when hitting the combusion chamber, vaporizes to nearly pure oxygen, thus enhancing a total burn in the combustion cycle. The bigger the shot, the richer the fuel needs to be to keep from burning exhaust valves, pistons, etc. That's why you have fuel nozzles with the NOS nozzles. It also has a cooling effect of the fuel charge on a hot engine, thereby limiting detonation.

In a nutshell, and THUS, and this is general physics here, if you're burning much more fuel, you need to get the gasses out much more quickly or you'll have a buildup that leads to catastrophic events. This is where you hear of manifolds being blown off or cracked from the stuff. :banghead:

You have a solid enough foundation for NOS, I would approach cautiously on the size of the shot. 100hp shot, in a boat, to me would seem a monumental increase all things being equal. More that that will likely require an impeller change to realize the crafts new HP curve. Then again, when off the bottle, if the impeller is tailored to when you are on it, performance is going to suffer.

It's a nasty quagmire.

Ray

Ray

Title: Re: A nitrous question for seasoned professionals....
Post by: BOOST on February 06, 2009, 07:39:54 PM

 Me and my Dad change out the snail logs on his boat for some center risers made a world of difference.

Title: Re: A nitrous question for seasoned professionals....
Post by: electrowoman on February 07, 2009, 01:40:37 AM

Where could I get a set that will clear the tall valve covers?   I can't use headers over the transom because of the sun deck.   

Does anyone know of a better set of manifolds than the long bolts that would clear  tall valve covers??

One other thought, the ride plate is lowered a bit from a few years back with multi skiers and a boat load of people.  I wonder if moving it back up would help pull the nose up and MPH?

What do you think?  I believe we lowered it about an inch or so.

Title: Re: A nitrous question for seasoned professionals....
Post by: Ralph Brunt on February 07, 2009, 07:29:42 AM

Quote from: electrowoman on February 07, 2009, 01:40:37 AM

One other thought, the ride plate is lowered a bit from a few years back with multi skiers and a boat load of people.  I wonder if moving it back up would help pull the nose up and MPH?
What do you think?  I believe we lowered it about an inch or so.

start at 2*up and go from there

Title: Re: A nitrous question for seasoned professionals....
Post by: electrowoman on February 07, 2009, 09:15:53 AM

I'll make a note and try that first thing.   We are dealing with hard water at this time though  :banghead:

Title: Re: A nitrous question for seasoned professionals....
Post by: beerjet on February 07, 2009, 09:54:47 AM

There is always the spendy Lighting headers.

I've trashed a perfectly good impellor a year or two in .
It actually only takes one good sized grain of sand to trash an aluminum impellor.

There is a reason why these racers tear there pumps apart after every race.
Success is in the details my freind.
Thats a part of running gear you can access regularly.
Not saying after every run but make it part of regular maintanance.

-beerjet-

Title: Re: A nitrous question for seasoned professionals....
Post by: electrowoman on February 07, 2009, 10:14:35 AM

If I pick up a new replacement impeller will it need to be "fitted" or are they plug and play?

Where do you check the gap of the impeller?

Title: Re: A nitrous question for seasoned professionals....
Post by: Luckie Stiff on February 07, 2009, 10:14:49 AM

even a set of Bassett TT headers will be sufficient, I've seen them run with no problems in boats with engine compartments, just make sure you've got good fresh air intake and exhaust vents, turn on the bilge blower at idle, you'll be fine. Fu-ck lightning and there $3500 headers!

Title: Re: A nitrous question for seasoned professionals....
Post by: electrowoman on February 07, 2009, 01:42:27 PM

Bassett doesn't recommend their headers for covered applications like mine.  I wonder if they clear tall valve covers though?

Title: Re: A nitrous question for seasoned professionals....
Post by: Ralph Brunt on February 07, 2009, 02:20:49 PM

Quote from: electrowoman on February 07, 2009, 01:42:27 PM

Bassett doesn't recommend their headers for covered applications like mine.  I wonder if they clear tall valve covers though?

i had a set of bassett tt headers with the ford motorsport v/c and they cleared with no probs. i would not put those headers under an engine cover, those suckers get hot :o

Title: Re: A nitrous question for seasoned professionals....
Post by: Luckie Stiff on February 07, 2009, 04:02:13 PM

(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi16.photobucket.com%2Falbums%2Fb49%2Fleeannrodie%2Fimg_0235.jpg&hash=b3b0f46848c228d2545ccd942235faf52bbe37fb)

I asked this guy about his TT's under cover when I had the RC cruiser, he said he's never had a single issue with them being enclosed?

Title: Re: A nitrous question for seasoned professionals....
Post by: SLCKREG on February 07, 2009, 04:17:57 PM

It's not legal.

Title: Re: A nitrous question for seasoned professionals....
Post by: Luckie Stiff on February 07, 2009, 04:21:50 PM

Quote from: SLCKREG on February 07, 2009, 04:17:57 PM

It's not legal.

Says who? If the guy was really concerned about heat he could double wrap them with heat tape.

Title: Re: A nitrous question for seasoned professionals....
Post by: electrowoman on February 07, 2009, 04:54:04 PM

I don't think the Bassett would fit in my engine compartment.   The old risers were within an inch of the ply wood of the engine cover.  It would seem risky to me in my application to use non water cooled anything in there.

 The picture of the headers above look higher then the old one's and would be right under the cover if they fit at all.

Here's a pic of the originals, and mounted on the old engine.  Notice how close they are at the side also.  When the hatch closed at the front it was right above them.

Title: Re: A nitrous question for seasoned professionals....
Post by: BOOST on February 07, 2009, 06:02:45 PM

 Those old headers will out perform the ones you got on their now.

Title: Re: A nitrous question for seasoned professionals....
Post by: Luckie Stiff on February 07, 2009, 06:29:24 PM

Quote from: boost on February 07, 2009, 06:02:45 PM

Those old headers will out perform the ones you got on their now.

That they will! Why don't you just make get (or make, or have made) new tops that don't rise so high?

Title: Re: A nitrous question for seasoned professionals....
Post by: jet boat performance on February 07, 2009, 07:57:30 PM

Quote from: electrowoman on February 05, 2009, 11:29:03 PM

I've been thinking about using nitrous in my 460.  I have no experiance with it so I'm hoping you guys can answer a few questions for me.

1.  The engine is fresh, built well with forged pistons, eagle rods, edelbrock heads, 850 Holley, Hi vol fuel pump and a very stout valve train with stud girdle.  It runs around 61 MPH at 5000 to 5100 RPM's now.  I would like to try 100 to 150 HP shot.   Should this be a wet system for that HP range?  What do you think of the ZEX setup?

2.  Does nitrous really do any good in a boat??  What RPM increase would you think it would produce?

3.  What size bottle?  One or two?

4.  Roughly how long does a bottle last say 20# at 100 HP setting.  150?

5.  What does it cost to have one refilled and where do you have that done?

  This would be for a once in a while short burst operation, not running all day WOT.... 

  It's 2 degrees outside right now,  where oh where is summer?

  Thanks for the help in advance!

Nothin wrong with squeezin that motor a little and it sounds like your motor will handle it well , Crew is right on the fuel deal IMO , re the exaust's the cleanest safest most economical is the late style center rise Like the Eddies around  2k to you from us , they will perform every bit as well as the thru hull headers and they run "cool" Mine were a near direct bolt up to replace the logs and rizers (my motor box touches the edges of the mans) Zex (prefer NOS ) is good the ,"bottle longevity" is relative to how long your on it  ;) ( check Eddie dyno results below) thats why I chose them I running 9.5 to one with 6 lbs of boost  those Ex mans will handle a lot more Tom

http://www.eddiemarine.com/techsupport/assets/emi_dyno502_5483_3.pdf
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi147.photobucket.com%2Falbums%2Fr319%2Fjetboatperformance%2FEliminator%2520V-drive%2FResizeofDSC00306.jpg&hash=6887eeedca531f55c58fe2c118d8c4aadb386bdb)

Title: Re: A nitrous question for seasoned professionals....
Post by: electrowoman on February 07, 2009, 09:36:37 PM

Now for the big question,  will those pipes clear tall valve covers?  They seem as tight as the originals
on my boat.

Title: Re: A nitrous question for seasoned professionals....
Post by: ROMPERSTOMPER on February 09, 2009, 02:47:12 PM

A 100 shot would be fine with your current set up. I would run 1-15 pound bottle. 5  runs. 10 if there short. The more pressure  the better. Zex has the best plate kit I think. You can fill it at most speed shops. 3-4 bucks a pound. I would run ot bassets if you run more. Ifs its a 4 bolt and h beam rods you could run about 300 +. Dont think you want to go that route tho, you would need to make a lot of changes.  Im running a 300 on mine but the boat is completely set up for it.

Title: Re: A nitrous question for seasoned professionals....
Post by: electrowoman on February 09, 2009, 09:51:36 PM

Thank you Romper for your info.   I think I'll  stick on a 100 shot and see how she likes it.  If it does work well should I pick up a heating pad too?

Thanks again

Title: Re: A nitrous question for seasoned professionals....
Post by: electrowoman on February 10, 2009, 10:41:50 AM

It seems the big unanswered question for the exhaust manifolds is do they clear the tall valve covers?

I've always used stud girdles in my drag racing engines, I woudn't  even consider building a boat engine without one. 

What do you guys run for valve train?  Does anyone know of a set of valve covers that will clear the girdle and manifolds???

Title: Re: A nitrous question for seasoned professionals....
Post by: ROMPERSTOMPER on February 10, 2009, 02:58:26 PM

I ran the same set up. crane rollers and girdles. edelbrock tall covers. they look taller than yours and my bassets cleared fine. Im running $haft mount rockers now, so no need for the girdles. Also nitrous express has a very nice plate kit if you want to go big. check out there site. talk to Craig if you have tech ?'s.1-940-767-7694. he can tell you everything you need to know and what would work best for you motor. they have a plate kit that does 50-800 hp. crazy!