someone clear this for me?pls.

[HondaCivicEx98]

After doing some intake experiment, i noticed that my PSI reads higher with the stock air box in VS the 2.5 in with k&N filter on stick. Does higher reading on the boost guage contribuit better flow and that the stock box works better then the 2.5 stick filter?

Stock box: less responds(off boost), better high end power(under boost).

2.5 in with K&N filter in stick:Better responds(offboost), lack of high end power(under boost) and stoich faster then stock air box.
thanks

[johnyew]

The higher PSI reading you're getting is because the stock air box is more restrictive than your stick filter. Air velocity is reduced causing pressure to increase.

[HondaCivicEx98]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>The higher PSI reading you're getting is because the stock air box is more restrictive than your stick filter. Air velocity is reduced causing pressure to increase.<HR></BLOCKQUOTE>
Are u sure of this? i thought that bette flow would increase PSI eading on SC cars.
Anyway, since i got too much spare time, i slap in my 3" intake with the filter. my psi almost pump it to 8 psi at higher RPM.
what does this all mean after all.
Some more people help. pls.
thanks

[fastfour]

From what I have seen, the more restrictive your system is the higher (to a certain degree) your boost readings will be. This is why some people here have seen the boost hit 8 psi with a 6 psi pulley with stock I/H/E. When they move to a freer flowing system the boost readings come down to 6 or so.

Zach

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94 Civic Coupe/LS Hybrid
JRSC@6psi
Turbo Convert
Import Specialty Automotive (253) 473-2606

[4drsleeper]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by fastfour:
some people here have seen the boost hit 8 psi with a 6 psi pulley with stock I/H/E. When they move to a freer flowing system the boost readings come down to 6 or so.

Zach

<HR></BLOCKQUOTE>

Exactly right. I currently run 8-9 PSI with the stock pulley on my GSR. I have a silencer in the exhaust which puts me at 9PSI, when I remove it I get more power and drop to 8PSI. More PSI does NOT mean more power.

[HondaCivicEx98]

So how i do i expalin this?
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>For SC only:
Free-er Exhaust = Lower boost readings. (As a side benefit, temperatures in the blower, intake manifold and cylinders go down.)

Free-er Intake = Higher boost readings.

Both result in higher "actual" boost/power.

For the record, I'm from the "cold-air/long-pipe is better than hot-air/short-pipe" camp. Of course, I drive through the winter, so I sometimes enjoy the power of -10F air.<HR></BLOCKQUOTE>.

Sorry guys, it is not that i am not beliveing u guys, but it just makes me confused seeing different answers. cool?

[dbman96]

You can explain it if you look at a compressor map. Along the map are several curves which show that when the compressor is turning a fixed speed, if you increase flow through the compressor, you decrease the pressure rise; conversely if you decrease flow (as you are doing with the more restrictive airbox), you increase the pressure rise. As mentioned before; this only meanse a greater pressure rise; since this is happening as a function of reduced flow, you are not getting better performance out of this higher "indicated" boost.

Don't know if that helped... there are some compressor maps posted somewhere at turbonetics.com that will help you to picture this, I think.

[johnyew]

try this for yourself...stick a potato in your exhaust and check your PSI reading. If what you say is true, then the PSI reading should be lower, right?

[dbman96]

um... if your boost gauge is reading your exhaust pressure, you've got bigger problems than a potato in your exhaust.

[JRCivic]

Superchargers like to pull from slow moving air... smaller, longer intake tubes create slightly higher velocities over their shorter counterparts. Higher velocity means increased HEAT... increased heat means that the cycle of air that is pumped through the blower is larger in area, and when confined to a fixed space (your intake manifold), the pressure readings are higher.

On the exhaust side, when the exhaust is more restrictive, the pressures are typically slightly higher. This is due to the leftover spent gas in the chamber that is quite hot. When mixed with the incoming fresh air/fuel in the manifold, you get greater expansion from the higher temperature... thus, greater boost readings.

Important note here: more pressure is NOT always better. You get much more power from cooler, lower boost pressures than from hot, higher boost pressures.



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'93 Civic Si H/B with B18C1, JRSC @ 8psi
Best 1320: 12.68 at 110 mph