more air = less boost?

[Don Tanklage]

would someone care to explain this?



if you put a larger compressor side on the thing and it moves more air (into the same intercooler and engine) how could you end up with less pressure?



i dont get it...



don

 

[Makaio]

would someone care to explain this?



if you put a larger compressor side on the thing and it moves more air (into the same intercooler and engine) how could you end up with less pressure?



i dont get it...



don

Don,



I think the only way that statement would be true is if you increased 'more air' in terms of volume. Adding a larger inter/aftercooler with larger diameter intake tubing will drop boost a little. Give your thread time as others will chime in.



Aloha,

Matt

 

[Jgolden]

I increased the impeller on the compressor side of my turbo from 50mm(stock non IC) to 58mm that was what HTT then called stageII. I also then had to increase the crossover pipe to size to match the outflow from the compressor.

Can't say I got less boost but I didn't get more. What I got was lower egt's and more top end power. Maybe more air volume. I know you can try put too much air through the system but I haven't seen any sign of that problem.

Now I might be able to use more fuel but meets my needs so far.

At the same time I added a gigantic Donaldson 4" in and out muffler, Donaldson specs show very low resistance to flow (would be a tight squeeze under a pick up but on my motorhome it is real quiet ).

Put all these together and it runs and pulls better, and as a bonus my collision avoidance system now only has to yell not scream.

I'll take a test drive out west and plan next step.

 

[Don Tanklage]

i didnt mean more volume in the system, gonna leave all that alone. besides, wouldnt that just make it take longer to get to max boost - but not change the pressure?



i am going to a dodgezilla from a h1c/14 non wg. keeping the 14 for now, just replacing the cartridge and compressor. brad said it might make 1 or 2 pounds less boost. thinking about it i dont really understand why? one would think if you try to cram more air into the same motor the pressure would increase. doesnt really matter, just want the thing to climb better but retain its towing ability. right now barely any throttle and it is at 10 psi on level ground (in 4th over or 5th, at 21k pounds) (cruising at 1800 rpm)

 

[NIsaacs]

Maybe with the larger compressor side and more air, the turbo rpm is less with the same pressure going into the drive or turbine side





"NICK"

 

[Don Tanklage]

wouldnt that mean it is less effecient?



more pressure on the drive side (assuming the turbo makes more back pressure at less rpm) and less boost on the other side



hey, what is "mono beam"?????? (1976) (in your sig)



thanks, don

 

[NIsaacs]

"wouldnt that mean it is less efficient?"



Maybe... turbos are very complex to me... mixing and matching compressors, housings, turbines and housings can sometimes get all wrong for an individual application based on how the engine is configured. Look at all the different choices available and all the questions members ask. "Will it work for me?"



The "mono" beam axle just means "one" as in single I beam. The Ford's all used "twin I beam" with coil springs. I cut all of the old out and installed the single with leaf springs, kinda like the 4x4's used. I don't like it, it is hard to keep on the road. Rather then the standard reverse elliot type, or the king pin solid in the axle and pivoting on the spindle, it is solid in the spindle and pivots in the axle. Or elliot type. One of Chrysler's own ideas





"NICK"

 

[Don Tanklage]

how could anything be hard to keep on the road with a ctd on top of it?



lol



glad i asked, was thinking about doing something like that to the frnt of mine someday, with bags tho...

 

[Joseph Donnelly]

Remember your high school chemistry? PV=nRT. If the new compressor is more efficient at pumping the amount of air the turbine section is “requesting”, the boost air temperature will be cooler and therefore at lower pressure for a given amount (n=number of moles or roughly the weight) of air molecules.

 

[dpuckett]

Yup, Joe has it right. ALso keep in mind that boost is nothing more than reisstance to flow of air (I think I have read that in Joe's writings in the magazine). More boost doesnt, in and of itself, equal more air. See PV=RT. If you increase temp, pressure has to go up as well, all else being equal.



Now, I added a 2ndGen intercooler to my pickup to replace my wastegated stock unit. I have about the same peak boost (35-36), but peak EGT dropped more than 200deg to about 1100-1150 on a 105deg (shade, like 2/3 of the USA right now) day. I imagine on an 85 deg day, I'd top out around 1000. That tells me 1) it is moving more air, and 2) the stock system is more restrictive than the 2ndgen, though the leaks in mine are a factor, so dont take my experience for absolute truth and expect the same results if your IC is in good shape.



Daniel