Hey board-
I am slowly restoring and modifying my 84. I have made the following changes for power:
2.5" Downpipe back exhaust
Custom cold air kit
Grand National intercooler swapped in place of AC - 2" charge pipes
newer computer and jumper harness (thanks slow)
The car is running more boost now, but is effectively slower, especially in first. I am thinking the charge pipes are longer and need more time to get to the desired boost levels. Unfortunately, I have to shift out of 1st before the desired boost builds...
You feel the higher boost in 2nd and 3rd as you are in those gears longer...
I routed my pipes through the opening that the stock air box used. The problem is the orientation of my intercooler setup (necks at top) requires a extra two feet of charge pipe to wrap back around to use the same hole. I wanted to save on fab work until I was closer to my ideal setup.
Seems like I am a good match now for stock 94 Camaros with the 3.4 V6. I had set my aspirations a little bit higher...
Any idea what the lag per inch or foot of charge pipe? I know what I need to do here, just looking to see if there is a known formula.
Thanks,
You will need several equations to calculate what your looking for. You first need to find the Reynold's number, pipe friction coefficient including the fouling factor if any applicable, probly not tho. Then with those known you can go forward and calculate the pressure drop across a length of straight pipe. You will need to find the 'effective length' if you have any bends you want to include in the calculations. Basically taking all the 90's and other bends and calculating how much pressure drop a length of straight section would be equivalent to each bend you have and then using the new length as the actual length in the pressure drop calc.
"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
Let me back off my original question a bit. Does my theory sound reasonable? Shorter charge pipe=quicker boost build?
Paul94Z28 wrote:Let me back off my original question a bit. Does my theory sound reasonable? Shorter charge pipe=quicker boost build?
generally yes, the air has less distance to travel before reaching the engine, also pipe diameter make a diffrence, with larger piping u get less velocity, which can sometimes be offset by the fact that its more volume, try and findt he ideal pipe diameter, to maintain good speed and quantity of the pressurized air, also is the intercooler really neccessary? at low boost levels its generally not a neccessetity, you could look into water/air intercooling to have the shotest amount of intercooling piping, this would give u the best of both worlds, u get short charge piping, which will allow the boost to enter the engine faster, andyou get intercooling, best of both words, its just water/air is not as cheap as air/air
So lets say 10-12lbs of boost tops...
Do I need the intercooler? If not, the problem goes away...
Yes you would see some benefit from the intercooler at those pressures. First off, running out of first gear before boost builds isn't exactly the worst thing in the world. The first gear in my car last all of 2 seconds. Also, 2" charge pipes are perfectly fine. At those boost pressures it would be reasonable to find boost not 100% built until the second gear.
"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
Also take into account that you'd probably shred the tires if you had full boost in first, consider it a benefit!
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and yes, water/air is more expensive than air/air
More than likely it's in the tuning.
-->Slow
