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Couldn't brake boost at the track?

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joyfil2001

joyfil2001

15+ Year Contributor
838
1
Dec 17, 2007
Toms River, New Jersey
So I went to Atco yesterday feeling pretty confident. For some reason I couldn't build more than 7psi while brake boosting. I have never had a problem before. So after three runs I tried it later. I built 17psi no problem and launched like a bat out of hell! WTF?

My wife seems to think it may have some thing to do with the car not being warmed up enough when I got to the tree at the track.

Any Ideas?
 
Your car just said im the boss and im not gonna let you brake boost at the track. hahaha
 
It did get colder out. But why would that affect it?

Here's another question: My car won't go past 6000rpm in 4th gear(over-drive). Both runs at the track I trapped 103mph and it felt like I hit the rev limiter in 4th but I was only at 6K rpm. Any idea what would cause this?
 
When I had my automatic tranny, it would NEVER launch at the track. It always fell flat on its face. I tried even putting an external transmission cooler, which looked like a little front mount. Nothing seemed to help. UNTIL, I did my 5 speed swap. Now it launches great!LOL

My car would launch great when it was cold or when I was around my town. As soon as I took the hour drive to the track, it wouldn't launch at all.
 
DSM4me44 said:
When I had my automatic tranny, it would NEVER launch at the track. It always fell flat on its face. I tried even putting an external transmission cooler, which looked like a little front mount. Nothing seemed to help. UNTIL, I did my 5 speed swap. Now it launches great!LOL

My car would launch great when it was cold or when I was around my town. As soon as I took the hour drive to the track, it wouldn't launch at all.
Click to expand...

See mine is acting the opposite. It likes to launch after driving around. Letting it sit at the track with the engine off for 45 minutes made it not want to brake boost. I will be going back soon.
 
Just leave the car on when your waiting in line... Or do some practice pulls right before you get in line...
 
With cars running at the track all day, especially without cats, the whole dragstrip area is filled with c02. When you drive on the road you have more o2. The o2 is what builds the power to break boost the car, as where the co2 hurts power. That is also why you tend to run a tid bit richer on the strip instead of the street.
 
domthebomb11208 said:
that weird..are you using the e brake for launches? what are your current mods to the car???
Click to expand...

Don't need the ebrake. The car doesn't move.

Bender said:
With cars running at the track all day, especially without cats, the whole dragstrip area is filled with c02. When you drive on the road you have more o2. The o2 is what builds the power to break boost the car, as where the co2 hurts power. That is also why you tend to run a tid bit richer on the strip instead of the street.
Click to expand...

That's interesting.
 
Bender said:
With cars running at the track all day, especially without cats, the whole dragstrip area is filled with c02. When you drive on the road you have more o2. The o2 is what builds the power to break boost the car, as where the co2 hurts power. That is also why you tend to run a tid bit richer on the strip instead of the street.
Click to expand...

yeah, I guess cars don't emit cO2 on public roads right? :rolleyes:
 
You emit co2 on pubic roads, but its not channeled between two contact barrier walls. Not to mention the levels of co2 admitted on the street are far less because 90% of the cars on the road have catalytic converters. Not to mention there is time for all the gasses to dissipate when your doing it on the street (i doubt you are launching on the street in stop in go rush hour traffic) as compared to the drag strip it is one right after the other.

On a side note I have the same problem. In the parking area of the drag strip i can boost up fine, but as soon as I get on the actual strip it doesn't boost at all. You got to go when the gates open and be one of the firsts in line before a bunch of cars can lay down passes.
 
Bender said:
You emit co2 on pubic roads, but its not channeled between two contact barrier walls. Not to mention the levels of co2 admitted on the street are far less because 90% of the cars on the road have catalytic converters. Not to mention there is time for all the gasses to dissipate when your doing it on the street (i doubt you are launching on the street in stop in go rush hour traffic) as compared to the drag strip it is one right after the other.

On a side note I have the same problem. In the parking area of the drag strip i can boost up fine, but as soon as I get on the actual strip it doesn't boost at all. You got to go when the gates open and be one of the firsts in line before a bunch of cars can lay down passes.
Click to expand...

wow. Seriously? You think a 2 foot wall is holding in CO2? Not only that, but you have 2 cars passing every 20-30 seconds. Highway has constant traffic. Track is wide open where road is not.
 
Well. Then what's your take on why people have these problems, yet can brake boost just fine in the parking area of the track? I've even tried under the same conditions. ie. cold engine temp, hot engine temp, cold weather, hot weather, on grass, and on hot asphalt.
 
There's a lot of factors. Converter heat, fluid temp (and it's effect on viscosity), inconsistency in the tune, air temp, underhood temps, air pressure.

If your car isn't stalling up 100% of the problem you either need a looser converter or more low end power. Need to worry about that, not how much emissions there are.

I've dynoed cars in shops with terrible ventilation where the difference in power from clean air to when you couldn't breathe was about 10-20 whp on a car making 400-500 whp. The small difference in air quality (if any - I'd seriously believe the quality to be higher at a track then public road anyways) is negligable.
 
I understand what you're saying about the air quality, but I've tried to replicate the different conditions to the best of my ability.

Well, now that I think of it, though, I did have a bad torque converter. With this IPT rebuild I'm going with a bigger cooler, and a temp gauge.

On the same note, do you think a cooler rated for 22,000 GVW (Tru-Cool doesn't give a BTU) would be overkill and not let the trans heat up to a proper temperature? And I've read about many people installing the sending unit for the gauge on the cooler line.. but wouldn't it be more accurate if it was mounted in the trans pan? It seems to me right after the cooler is only going to show the coldest temperature the fluid is getting to. I would rather know the temperature the transmission is using it at.
 
I don't think you can go too big on the cooler. As far as the temp sender - there's not going to be much variance. Do you want to know the temp of the fluid you've got going into your trans to be used? or the temp of the fluid coming out of the trans? I guess the hotter spot would be better to look at. but if you have a badass cooler it may be misleading.
 
I guess I just want to know the hottest the fluid is so I could tell when the fluid is getting too hot. So maybe I'll just put it on the line going to the cooler so I can get a sense of how hot it is. Then I'll put it on the line going to the transmission so I can see how efficient the cooler is. Then I can see the temp of the fluid the trans is using, and estimate how hot it is before the cooler. The cooler I'm looking at is 12x11x0.75, and I'm going to run it in my fender well, with a designated fan if need be. Also, I responded to your pm about line pressure.
 
I'm just sick of it not being consistant. It's always a guessing game whether or not the car is going to build boost at the line. I would rather it be one or the other rather than telling people it launches like a rocket and then looking like an ass when I can only build 5psi.
 
Is nitrous the only way to help spool? Can meth do the same thing? I can't afford a nitrous kit or a meth kit. But I can afford to make my own injection kit. If I only need to use it to help spool (before launching) then a simple direct injection by toggle switch would be easy to put together.
 
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