boost gain with smaller pulley strange, any ideas?
10-10-2011, 01:53 AM
#1
Thread Starter
boost gain with smaller pulley strange, any ideas?
Hi guys,
I recently upgraded from a 4.0" pulley to a 3.8" (its actually an sos 3.6) this is the outside diameter. It's modified as per reichard.
The last pulley 4.0" yielded 8psi at Redline, I thought the 3.8 would yield 9psi due to. 2" (even sos site says this for a 3.8 (sos 3.6) to yield 9psi, however its making just over 10.2psi at Redline confirmed by the dyno and my greddy emanage ultimate logs and greddy boost sensor.
What gives? Temp hasn't changed much so it's yielding over 1psi than it should do and I measured the pulleys outside diameter.
Cheers
I recently upgraded from a 4.0" pulley to a 3.8" (its actually an sos 3.6) this is the outside diameter. It's modified as per reichard.
The last pulley 4.0" yielded 8psi at Redline, I thought the 3.8 would yield 9psi due to. 2" (even sos site says this for a 3.8 (sos 3.6) to yield 9psi, however its making just over 10.2psi at Redline confirmed by the dyno and my greddy emanage ultimate logs and greddy boost sensor.
What gives? Temp hasn't changed much so it's yielding over 1psi than it should do and I measured the pulleys outside diameter.
Cheers
10-10-2011, 03:14 AM
#2
Every car is diferent, its just the way it is I guess. Did you monitor your boost levels before changing? Perhaps the belt was slipping before... Make sure you have enough fuel and just run with it 
10-11-2011, 11:56 AM
#6
Thread Starter
Cheers Chris, good know its not abnormal, i only seemed to yeild around 30BHP/14 lbft torque @crank from an increase of 2 psi though, thought it would have been more 
The last made 8psi then this one .2" smaller made 10psi
The last made 8psi then this one .2" smaller made 10psi
10-11-2011, 12:12 PM
#7
Hey dude! Thats right on par with what 2psi yields on a SC in its average efficiency range. 15whp/7trq. f22 will make a little more generally. But as you make more boost, heat goes up and efficiency diminishes. Your next smaller pulley or two may only yeild you 10hp/4trq. That’s how the cookie crumbles. Better flowing exhaust and a larger cfm blower will help retain your efficiency to a higher level. I noticed you said @ crank, which yes is a little low, but AIT can play a big part in that. Make sure your Aftercooler is up to snuff to keep those temps in check so you can get the most bang for your buck.
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10-11-2011, 12:19 PM
#8
Thread Starter
Its that 15whp per psi though? as i only made 30BHP @ crank with an increase of 2 psi so doesn't add up?. But yeah point taken about efficiency
I have the following bolt on's
Tracysport jethot coated header.
5zigen 63mm single pipe exhaust and berks HFC.
Custom made snorkle to the front of the filter in the CT icebox.
And 4.56 gears
The greddy reports 29c in WOT and it seemed to hover around this figure throughout the rev range - but i think this is a little low, i will use my OBD2 scanner to get a better more accurate figure as i reckon it will be in the 40c's, however IIRC hondata said the stock ECU doesnt pull timing until >=45c in wot.
I have the following bolt on's
Tracysport jethot coated header.
5zigen 63mm single pipe exhaust and berks HFC.
Custom made snorkle to the front of the filter in the CT icebox.
And 4.56 gears
The greddy reports 29c in WOT and it seemed to hover around this figure throughout the rev range - but i think this is a little low, i will use my OBD2 scanner to get a better more accurate figure as i reckon it will be in the 40c's, however IIRC hondata said the stock ECU doesnt pull timing until >=45c in wot.
10-11-2011, 12:35 PM
#9
Its that 15whp per psi though? as i only made 30BHP @ crank with an increase of 2 psi so doesn't add up?. But yeah point taken about efficiency
I have the following bolt on's
Tracysport jethot coated header.
5zigen 63mm single pipe exhaust and berks HFC.
Custom made snorkle to the front of the filter in the CT icebox.
And 4.56 gears
The greddy reports 29c in WOT and it seemed to hover around this figure throughout the rev range - but i think this is a little low, i will use my OBD2 scanner to get a better more accurate figure as i reckon it will be in the 40c's, however IIRC hondata said the stock ECU doesnt pull timing until >=45c in wot.
I have the following bolt on's
Tracysport jethot coated header.
5zigen 63mm single pipe exhaust and berks HFC.
Custom made snorkle to the front of the filter in the CT icebox.
And 4.56 gears
The greddy reports 29c in WOT and it seemed to hover around this figure throughout the rev range - but i think this is a little low, i will use my OBD2 scanner to get a better more accurate figure as i reckon it will be in the 40c's, however IIRC hondata said the stock ECU doesnt pull timing until >=45c in wot.
10-11-2011, 12:47 PM
#10
Thread Starter
Possibly, but i dont think its the header the only thing i will say is in roughly the same conditions on the same dyno.
My mates s2000 running 7psi CT+AC, FPR and a testpipe made 320BHP, mine the same but with a VAFC2 and tracysports header and t1r v2 singlepipe made 350bhp.
Back in the n/a days when i added a tracysports header it seemed to add power in the midrange and higher up.
My mates s2000 running 7psi CT+AC, FPR and a testpipe made 320BHP, mine the same but with a VAFC2 and tracysports header and t1r v2 singlepipe made 350bhp.
Back in the n/a days when i added a tracysports header it seemed to add power in the midrange and higher up.
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