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Discussion Starter · #1 ·
Building a nitrous motor from scratch. Gonna run carbs. I've never had more than a 100 shot so what's people's opinions for a all out build? Keep stock displacement or go big? Going to isee a gen1 or 2 motor haven't decided yet.
 

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Depends on how quick or fast you want to go. I would recommend you contacting a shop that truly knows based off of what they themselves prove on the race track. Anything else you'll most likely get what you pay for! Total weight, tire size, transmission, chassis, and many other factors come to mind. I personally prefer the Gen1 head for an all out nitrous build. If you keep it small the stock block will do. If you go a little bigger Gen1 Block. If you go all out a custom block is best. What will live over time depends on most things listed above. I've done anything from Stock engines with nitrous with great repeat performance all the way up to the quickest nitrous Busa on the Planet. I'm very disappointed in what I've been reading here over the last few days regarding best way to do things. Hate to see so many in the long run spend much more overall. Good luck with what ever it is you decide. Me personally I haven't been on here in a very long time and most likely by the end of the day will not be back on so the blind can keep leading the blind.
 

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Discussion Starter · #3 ·
Thanks Bill. All info is appreciated. I just hate talking to all the big shops bc they mostly just push their work. And that might not really be the best way to go.
 

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I don't push my work cause I always have too much. Not saying all advice here is not good cause that's not true. Sadly knowing the difference is the hard part cause some people are thought to be creditable here.
 

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It won't let me view it. I wish I could have seen it in person. Are you gonna run any in Indy this season? I'd love to see a 3.98 in person man that would b the shit! I love that class of bikes it really gets the blood pressure up lol.
 

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They pulled the plug on that class and put a 4.60 class in it's place. The video was of the quickest run ever by a Hayabusa putting me number 1 qualifier ahead of the largest Pro Extreme field last year at the PDRA. It was a 4.04. I have the only bikes that have run in the 3's at the current heavier weight rule. Those bikes have Carbs while the Busa is injected. Under the current rules I have the quickest nitrous bike with carbs and the quickest nitrous bike with EFI.
 

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Yea I know and that shit sucks! u guys and prostreet are the ones I go to the line and watch the rest u can see anywhere.im hoping Brian keeps it in the nhdro. If he does you gonna come to Indy so I can stand near one of these bad ass passes lol? I really didn't know a nitrous bike in that class was puttin it down like this. Guess I got some words to eat lol.
 

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I'm very disappointed in what I've been reading here over the last few days regarding best way to do things. .
Can't agree more with this.

When talking with builders you might consider talking with them about thermal management and not power. Getting power with nitrous is trivial. Managing the heat it generates should be your first concearn. Everything about a nitrous build is about figuring out how to get the heat out. Start with the cylinder head. A typical builder will focus on getting good flow numbers. They cut back the guides and go with a 5 angle valve job with very tiny valve seat land. Big lift. Big duration. Big flow. All of this is secondary on a nitrous build. You need to get the heat out of the valve and seat, and the only way the valve can rid itself of heat is through the seat and guide. The stock seats in a busa head don't conduct heat fast enough and as a result, the ex seats burn or sink towards the plug or the head of the valve can even burn right off. Advancing the exhaust valve a bit helps get the heat out. Bigger seat lands and full size guides help get heat out of the valve. Bronze seats help conduct the heat faster into the head. None of the things I mention help create big dyno numbers but they make the motor live.

Other things to focus on also have no impact on power numbers. Oil pressure / flow / cavitation is a huge problem on these bikes, but very few people log oil pressure. Case modes, baffles and pickups are tremendously important. Proper Tune / Squish / and chamber design is critical for avoiding detonation. Having a means of smoothly feeding in the power (and adjusting the tune) is critical to ET. All of these things don't affect total power. A well set up 300 HP bike can smoke a 400 HP bike. These might be things you can ask your builder.
 

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Can't agree more with this.

When talking with builders you might consider talking with them about thermal management and not power. Getting power with nitrous is trivial. Managing the heat it generates should be your first concearn. Everything about a nitrous build is about figuring out how to get the heat out. Start with the cylinder head. A typical builder will focus on getting good flow numbers. They cut back the guides and go with a 5 angle valve job with very tiny valve seat land. Big lift. Big duration. Big flow. All of this is secondary on a nitrous build. You need to get the heat out of the valve and seat, and the only way the valve can rid itself of heat is through the seat and guide. The stock seats in a busa head don't conduct heat fast enough and as a result, the ex seats burn or sink towards the plug or the head of the valve can even burn right off. Advancing the exhaust valve a bit helps get the heat out. Bigger seat lands and full size guides help get heat out of the valve. Bronze seats help conduct the heat faster into the head. None of the things I mention help create big dyno numbers but they make the motor live.

Other things to focus on also have no impact on power numbers. Oil pressure / flow / cavitation is a huge problem on these bikes, but very few people log oil pressure. Case modes, baffles and pickups are tremendously important. Proper Tune / Squish / and chamber design is critical for avoiding detonation. Having a means of smoothly feeding in the power (and adjusting the tune) is critical to ET. All of these things don't affect total power. A well set up 300 HP bike can smoke a 400 HP bike. These might be things you can ask your builder.
I never use Bronze for exhaust seats in a 4 valve. Other than that I agree with everything else. LOL!
 

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I can tell you that the very fast guys don't run small motors on spray.
 

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I can tell you that the very fast guys don't run small motors on spray.
Yes I've
only been as quick as 6.60's in the 1/4 mile with a stock Gen1 crank with a 84mm bore .380 cams and stock valves. That's a true 1397, but that was years ago. Wonder what one could do now with what I've learned since then!
 
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