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2K views 15 replies 12 participants last post by  ULTRA 23 
#1 · (Edited)
What's the maximum compression you can have to run NOS or is all about the timing??
 
#6 ·
Dont sweat the compression ratio too much, just focus on having a good tune up in it and having the right parts, do some research before you run it, dont rush the install.

For a full tilt nitrous dedicated engine the popular compression ratios are about 13.5-14.0 but there are guys doing it with 15.5 and more.
 
#8 ·
I've been looking at this whole subject a lot lately. Our next motor will likely end up with as a nitrous specific build (unless I can't live without a blown alcohol deal after this weekend!!). There's a bunch of guys around that know a lot more about this than I do. Chris certainly has his chit together on the whole nitrous deal.
Gene Fulton reportedly just built a big inch (800+) nitrous specific motor with nearly 18:1... Mear mortals need not apply. A couple of the nitrous guru's suggest around 13:1 as a good CR with the most forgiving tune up window for a mild shot (less than 250hp or so). Above that CR, the timing and nitrous tune up window starts to get narrower.
 
#9 ·
same thing i herd bout 13-13.5 to 1 being the sweetest spot for motors that'll still see run time other than race. i built mine at 13.5 to 1 thinking i had a hookup on ethanol local, that deal dried up and i got left runnin $$$ gas all this past summer:)sphss even at 13.5 to 1 , tuning took a bit and i had the plate off countless times flowing it till i found the sweet spot with nitrous a/f. what the manufacture recommended left me runnin pretty fat, and i ended up at 8 psi flowing to get a nice lean safe plug reading.would imagine a 15 to 1 or higher motor would be alot header to tune on the bottle to get on that ragged edge:)grn
 
#10 · (Edited)
At the amount you guys are talking about, say a 350 shot, 13:1, 15:1 isn't that important so long as you pay attention to tuning details .......

When you get really serious about injecting a lot of n2o ... say, above 350 (mild, but, you need to watch as you put in more) and get to the 500, 1,200, 1,500 + range, then there's considerable more than compression ratio that needs to be designed ... Heck, check with Starkweather about a 1,000+ Shot and how a motor should be built to Endure more that a run or two passes ... I'm sure he'll give he can clue in ... afterall, he's now apparently the SoKal Motor Builder to ask about these things according to all the bullshit I see on this Fourm.
 
#13 ·
WTF is this Jak. Another chicken shit comment from the guy who has not raced all year?

I'm not any kind of an engine builder, never claimed to be one. I help certain people where I can and that I think are cool and good for the sport, some more than others. I have had ALOT of help along the way also, I always thank these people and always attempt to return the favor, always! I try to figure things out myself first, when I'm stumped I make a call or get online to an engine or nitrous forum and try to weed through all the BS for some good info. Thats how I work, my goal has been to depend on the least amount of people as possible and so far Im pretty much a one man deal with a few exceptions, made some good contacts that we dont abuse along the way.

As far as putting nitrous to a motor...Honestly, what you have you done other than sit there and watch someone else do your tune up for you? I started "scared to death" at 175 because of the 12 degree tune up thing and have since worked my way up into much bigger systems than you have run in Mrs. Money Penny and thats a fact. I was standing right there when you finally got the OK to run more nitrous last year and it WAS NOT you dropping the pills in and setting up the fogger, I watched the whole process. I will give you credit for tuning the hardware yourself and doing your keels etc. etc.. You deserve that but you dont setup your nitrous yourself so dont comment on what I'm doing. I ran 3 different nitrous tune ups at the June event to run the number finally ran .02 and never hurt a thing. That was more tune up changes than you made since your boat was put togethor Ill bet. I have not missed a race this year and every single pass was on the bottle while you were not racing so settle down on the cheap shots. Also took it to the river all season and there was a bottle in there every day it hit the water and it got used. Ask anyone on here if you dont believe me.

I agree with what your saying about huge nitrous and the tuning window but nobody in jetboats other than that critical mass guy on YB is running that kind of a load of nitrous in a jetboat.

Why dont you just put YOUR favorite tuneup in that thing and come to Ming this weekend. Id love to have a shot at the BLACK MAMBA. I really do try to stay out of internet drama these days but Ive been following all your little "mickey Mouse" jabs at me over the past few months and Ive had enough. You obviously have a new found issue with me and to be honest i dont care. If this is coming from Sampica that bums me out, I will say that.

Chris
 
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