LOW COMPRESSION on nitrous motors

[badfastbusa]

I am not poking at your nor saying your bike doesnt run well but the last person I heard say these exact words did the same theory with his lil turbo s1000rr and the never has and still doesn't run for chit, I'd much rather use a Dyno get it tuned and run data loggers and auto tuners after the fact to compensate for changing environments.

Sounds like the last person you heard say that needed someone more knowledgeable behind the laptop, twisting the wrenches, and possibly riding... A dyno is good for getting a base map tuned because its quicker, and safer (for the bike and the rider), although it is certainly doable on the street and track if care and patience is taken. Data logging, experience, and fine tuning to the environment and conditions is how you extract ever ounce of potential the combo has to offer.

BTW, lots of great info in this thread!

[N2Obusa1441]

I am not poking at your nor saying your bike doesnt run well but the last person I heard say these exact words did the same theory with his lil turbo s1000rr and the never has and still doesn't run for chit, I'd much rather use a Dyno get it tuned and run data loggers and auto tuners after the fact to compensate for changing environments.

Let me explain a bit more. Dyno's do a good job at getting a nice steady 5 second run in 4th or 5th gear. Thats interesting, but not very useful for a nitrous drag bike. Nothing in drag racing is that static. The motor comes off the 2-step and starts to hook up on the clutch. Meanwhile the first stage of nitrous starts to flow immediatly, followed shortly by the second stage of nitrous that starts to ramp. All this happens in 2 seconds. The logger is telling you how the clutch is coming in, and how the motor reacts to the progressive feed of the nitrous. Furthermore, you typically need to compensate for bottle pressure falling off at the top end of the track. I run a regulator and drop the pressure down to 750, but bottle pressure still fluctuates wildly over a 7 second pass. None of that information is available on a dyno. Here in New England, the DA might vary from -900" at the beginning of the season, to 3500" in July. Thats almost an 8 or 9% correction factor (I think) and thats the difference in a bike running 13.7 and 11.9 A/F. So even if you tune your bike perfectly on a dyno, how usefull is it 3 months later.

But thats just my opinion...

[alpinesupra]

@badfastbusa, yes he does he is a fcking moron his lil turbo bike barely starts, only made a 100hp run first Dyno and once issues are figured out makes 250hp @6psi but it took my brother to figure out what he ****ed up..... I guess I should also mention he is using a 60mm turbo on a street bike.

@n20busa, yes that does make perfect sense but I still prefer fine tuning on the Dyno and have the data loggers correct for verying attmospher differences, but like I said it wasn't a insult to you just saying the last dude to say that didn't know what he was doing.

[flyinphill]

Flyinphill,

I'm all ears. I appreciate any and all info/data. I will look up the Otto and start there. Thank you for help us rookies. We are listening and learning here everyday!

How basic do you want me to start?

[Pruitt'sBusa]

If you would just start out simple and try to stay focused toward the things that will help us rookies figure out how to come up with good combos and design setups for our Big Bad BUSA's. I appreciate your time and help very much.

Thank you,
Jason Pruitt

[Pruitt'sBusa]

Bump

[nitrousbusa569]

Alot of interesting views on this thread, but imo the topic is a bit over thought and correct all around setup is more important than focusing on one aspect such as compression. FYI I run my setup .065 PTH and still 1.21 to 1.23 60" weighing in at 240 suited.....

[flyinphill]

If you would just start out simple and try to stay focused toward the things that will help us rookies figure out how to come up with good combos and design setups for our Big Bad BUSA's. I appreciate your time and help very much.

Thank you,
Jason Pruitt

OK, I will just start at the beginning, even if that is too simple for some of you. But I have a super busy schedule this week, so I don't know exactly when I will have time to do it. It may not be until this weekend, when i am sitting around bored in Valdosta, that I have time to do it.

[MR AC]

this is a great topic and i will definitely be reading and checking back for updates.

[flyinphill]

Just to bump this thread, I have had several people ask me both here and in person at the track to expand on this. I will do it when I get the time, but I am in the middle of a major remodel on my house this week, so I have no time to do anything right now. But I will get to it in a few days, I promise.

[karlw/ak]

Bump

[BRUNOSBUSA]

Good thread Im watching I want to hear some more info..

[Moody]

i have ran as low as .040" pth clearance with good springs, I like to keep the ptv intake .060" exhaust .080", on the reverse side of that if you drop the piston down some in the hole this will allow you to degree your cams to possibly more desirable lobe centers. Listen guys, there honestly is hundreds of different ways to setup an engine. some will perfer one way over another, like some prefer suzuki over kawasaki.

[MR AC]

Just to bump this thread, I have had several people ask me both here and in person at the track to expand on this. I will do it when I get the time, but I am in the middle of a major remodel on my house this week, so I have no time to do anything right now. But I will get to it in a few days, I promise.

has it been a few days yet? lol

[Big J]

Alot of interesting views on this thread, but imo the topic is a bit over thought and correct all around setup is more important than focusing on one aspect such as compression. FYI I run my setup .065 PTH and still 1.21 to 1.23 60" weighing in at 240 suited.....

Joey what diet are you on...