Good points Carl. Thanks.The big advantage of CO2 is capacity - since it's a liquid in the cylinder the same size cylinder holds a lot more than if it were a pressurized gas like nitrogen (ballpark 500-1000x more at the same pressure, although a full nitrogen cylinder will have a pressure of about 4x the CO2 tank). I highly recommend having a spare CO2 cylinder at the track, as nothing is more frustrating than finding out you forgot to close the tank valve after your last run the last time out and now you have to pack up and go home without making a pass . Or having a fitting or hose come loose and run the tank down before you catch it. You can get the small bottles refilled at paintball stores or welding supply places, or you can get a 10 lb bottle and transfer line and fill them yourself.
A comment on one of your earlier posts: you started with both wg ports opened and then listed the effects of adding manifold pressure to the bottom port. An additional effect is that the wg will open much faster since the diaphraghm area is usually a good bit bigger than the wg puck area so the same change in applied pressure will result in a greater difference in force on the puck and thus more travel against the same spring constant.
I brought this up because someone told me about this procedure being done by some other turbo racers.This is a wastegate trick that I've heard of, but have not had the opportunity of testing yet. There are those on the track that are using the controller to hold the wastgate wide open during staging and then slamming it shut for the launch. The reasoning that I heard is, you have less exhaust back pressure working against the engine, so the engine can gain more rpm and increase exhaust flow energy. Sometime before the time to launch, the w/g is shut closed and the increased exhaust energy causes a increased rate of boost climb. Not exactly sure how that will work with my combination (nitrous and boost builder), but it sounds like an interesting trick to try out.
With a trick like this, I can see an advantage of using as light a spring in the w/g as possible. Although, as long as the spring is not too heavy so as to prevent complete opening of the valve, a heavier spring would assist the switching control pressure in shutting down the valve quicker.
I brought this up because someone told me about this procedure being done by some other turbo racers.
Frankly, I don't see how this could actually work.
Anybody else have any thoughts on this?
I just logged back on to post because I just realized that the stradegy was for the BOV, not the w/g. Scott, you beat me to it and explained it perfectly. Thanks.Reverse your current wastegate strategy/thinking and relocate it on the intake side. Popular boost control method on supercharged apps but also used on turbocharged vehicles(eliminates intake B/P and allows turbo to freewheel to desired boost pressure) Risky method if you don't keep an eye on turbine speed.
Maybe now we can discuss different launch and boost rise stradegies.
What sort of boosts are people using to launch on, and by the 1-2 shift point, how much boost are people finding to be the limit of traction for the shift? Please give a little info on your car such as hp level, ET/MPH performance, 60 foots, and tire size.
What is the quickest boost rise rate people are getting away with on the launch?
Well, when you unvail your car, you're going to have a lot of people peaking around then.Don't get me wrong. The AMS controllers are great units. I still use both to tune 2 different cars, the 1000 on a 7sec drag radial camaro and the 500 on a 8sec 10.5 mustang. I sold mine 'cause I found something else that better suits my car/preference. :wink:
Boost spikes on initial spool up is not necessarily a bad thing. For instance, if you have an engine that can ultimately handle 40+ psi of boost by the top end of the track, and the chassis/tires will only allow a 25-30 psi boost level at around the 60 foot mark, and the boost controller is set to a 25-30 psi level until sometime after the 60' mark, then a 2 to 3 psi spike can be safely tolerated, unless the spike causes a loss of traction.
QUOTE]
For me it did not cause a loss of traction it caused the car to Head up toward the sky instead of down the track.
When it would do a big wheelie I knew when I looked at the log the target boost was going to be over shot!! The travel limiters helped but with the instant center of gravity where it was to get maximum traction There was nothing I could when the car decided to throw more horsepower at the rear wheels than I anticipated. It just got frustating trying to out guess the boost controller. The problem was the MSBC 1 was not consistant
The big wheelies actually slow the car down. Like you said. The main goal is to keep accelerating forward down the track as fast as possible. This issue is now gone with the AMS 1000!
Chris. I would think that it wouldn't be that difficult to deal with that spike with the practically infinite adjustability of the ramps with the AMS. Am I wrong, Cal? Are there some boost spike situations where even the AMS isn't enough and engine tuning cutback has to be employed along with the controller?
Boost spikes on initial spool up is not necessarily a bad thing. For instance, if you have an engine that can ultimately handle 40+ psi of boost by the top end of the track, and the chassis/tires will only allow a 25-30 psi boost level at around the 60 foot mark, and the boost controller is set to a 25-30 psi level until sometime after the 60' mark, then a 2 to 3 psi spike can be safely tolerated, unless the spike causes a loss of traction.
QUOTE]
For me it did not cause a loss of traction it caused the car to Head up toward the sky instead of down the track.
When it would do a big wheelie I knew when I looked at the log the target boost was going to be over shot!! The travel limiters helped but with the instant center of gravity where it was to get maximum traction There was nothing I could when the car decided to throw more horsepower at the rear wheels than I anticipated. It just got frustating trying to out guess the boost controller. The problem was the MSBC 1 was not consistant
The big wheelies actually slow the car down. Like you said. The main goal is to keep accelerating forward down the track as fast as possible. This issue is now gone with the AMS 1000!
Could you give us some idea of what the value of the boost spike was that was causing the out of control wheelie? Thanks.