Dynamic compression ratio
04-22-2008, 10:26 AM
#12
3rd Gear Member
Join Date: Mar 2007
Location: Where gunshots are more common than birds chirping
Posts: 504
RE: Dynamic compression ratio
ORIGINAL: sxynerd
OK then people answer these questions.
Bore in Inches? 3.552 in
Stroke in Inches? 3.543 in
Rod Length in Inches? 5.933 in
Static Compression Ratio on a 99 2v? 9.74:1
Inlet Valve Closes ABDC? intake valves don't close right before a compression or exhaust stroke?
Boost Pressure in PSI ---- 11lbs and maybe 15lbs
Target Altitude ----- Sea level
OK then people answer these questions.
Bore in Inches? 3.552 in
Stroke in Inches? 3.543 in
Rod Length in Inches? 5.933 in
Static Compression Ratio on a 99 2v? 9.74:1
Inlet Valve Closes ABDC? intake valves don't close right before a compression or exhaust stroke?
Boost Pressure in PSI ---- 11lbs and maybe 15lbs
Target Altitude ----- Sea level
04-22-2008, 10:30 AM
#13
5th Gear Member
Join Date: Dec 2004
Location: In between Your Mom's Titties, skeet skeet..
Posts: 2,045
RE: Dynamic compression ratio
Well, IVC occurs shortly after the piston begins it's ascent back up.. It's not a whole lot, but it's enough to decrease Compression Ratio, in this case the dynamic ratio, by a fairly substantial amount.. If I were to guess, without any math, I'd say it's at roughly ~8.0:1.. This to me, wouldn't explainan explicitloss in boost pressure though...
Some turbo applications that I've seen boost drop off either leaned towards a wastegate issue (which is obviously not the problem here), or an intake leak of some sort... Do you monitor your A/F ratio at all?? If so, does it go rich during the drop off??
JT
Some turbo applications that I've seen boost drop off either leaned towards a wastegate issue (which is obviously not the problem here), or an intake leak of some sort... Do you monitor your A/F ratio at all?? If so, does it go rich during the drop off??
JT
04-22-2008, 10:47 AM
#14
6th Gear Member
Thread Starter
Join Date: Feb 2006
Location: Virginia
Posts: 11,786
RE: Dynamic compression ratio
ORIGINAL: GodAmGT00
Do you use a CBV/BOV?? Have you done an intake leak test??
JT
Do you use a CBV/BOV?? Have you done an intake leak test??
JT
And, No I don't use a wideband.
04-22-2008, 11:06 AM
#15
5th Gear Member
Join Date: Dec 2004
Location: In between Your Mom's Titties, skeet skeet..
Posts: 2,045
RE: Dynamic compression ratio
You may want to do an intake leak test.. About how long has this been happening?? It doesn't sound like too many other folks have similar problems, which to me, seems like there is a mechanical (figuratively speaking) break down, whether the BPV spring is not that good, or the actual valve may not be working correctly..
How many PSI drop off by what RPM, if you know off hand??
JT
How many PSI drop off by what RPM, if you know off hand??
JT
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