a-trim pulley upgrade

7up · 06-29-2002, 02:31 PM

I was thinking of getting a new blower pulley to pump some more boost out of my a-trim. I was thinking of 2.87 6 rib pulley from ASP. Is this a good idea or is a crank pulley better for more boost? Would I need a bypass valve or would I still be in the safe boost range without one?

1995MGTS · 06-29-2002, 08:38 PM

I don't have an A-trim but here are my gains from adding a 7" crank pulley to my 6lb Powerdyne. The stock crank pulley is 6.5". I was unable to run up to 6000rpm due to spark blowout but you can see the hp/tq gains throughout the rpm range. http://www.msnusers.com/MustangMembe...hoto&PhotoID=6

7up · 06-29-2002, 09:03 PM

Thanks
That made quite a difference. I imagine it would be similar to the Vortech. Did you have the powerpipe on before you did the crank pulley?

keakua · 06-29-2002, 11:17 PM

i run an A-trim with the S-trim impeller upgrade (still an A-trim housing). i put on the 2.95" pulley and was getting around 10-11 psi in hot weather with the crappy stock plastic intake hose and no bypass. i just put on a 10 rib 2.5" pulley, race bypass, and intake tube i cut and made for about $30. just got it running last week, so no dyno, but so far its putting out a little over 18#s. if you do get a smaller pulley or even keep the one you got, shot peen the surface that the belt touches to make it a little more abrasive and you can gain boost by preventing slipping at high rpm. its not bad for the belt at all, and the crank pulley i got from vortech for the 10 rib was already done, dont know why they dont catch on and do the blower pulley

1995MGTS · 06-29-2002, 11:33 PM

To answer your question, no, I didn't have the powerpipe yet. After putting the powerpipe on and correcting for the spark blowout (gapping the plugs to 0.35), I was able to pull to about 6200rpm. The powerpipe shifted the curve to the right. I'm assuming your gains with the A-trim might be similar. Here are my last three dyno pulls with the powerpipe:

http://www.msnusers.com/MustangMembe...hoto&PhotoID=7

06-30-2002, 08:13 PM

I did the crank pulley on mine for warranty reasons. Take the pulley off the blower and it voids your warranty.

06-29-2002, 02:31 PM	#1
7up Registered Member Join Date: Feb 2002 Location: Greeley, Colorado Posts: 321	a-trim pulley upgrade I was thinking of getting a new blower pulley to pump some more boost out of my a-trim. I was thinking of 2.87 6 rib pulley from ASP. Is this a good idea or is a crank pulley better for more boost? Would I need a bypass valve or would I still be in the safe boost range without one? __________________ 91 lx convertible, Vortech a-trim, 2.87 blower pulley. 30lb injectors, 80 mm mass air, 255 fuel pump, flowmaster cat back, bbk long tubes and h pipe 299.3 hp, 355.5 tq(before h-pipe, headers) Ricer Hater's Club-member #16

06-29-2002, 08:38 PM	#2
1995MGTS Registered Member Join Date: Mar 2001 Location: Chesapeake, VA USA Posts: 69	I don't have an A-trim but here are my gains from adding a 7" crank pulley to my 6lb Powerdyne. The stock crank pulley is 6.5". I was unable to run up to 6000rpm due to spark blowout but you can see the hp/tq gains throughout the rpm range. http://www.msnusers.com/MustangMembe...hoto&PhotoID=6 __________________ 2003 Redfire Cobra #5978 of 8394 -Pro-5.0 -DC cai -Steeda x-pipe w/cats -Steeda cat-back -Lightning pulley w/Afterburner 441rwhp/434rwtq SAE

06-29-2002, 09:03 PM	#3
7up Registered Member Join Date: Feb 2002 Location: Greeley, Colorado Posts: 321	Thanks That made quite a difference. I imagine it would be similar to the Vortech. Did you have the powerpipe on before you did the crank pulley? __________________ 91 lx convertible, Vortech a-trim, 2.87 blower pulley. 30lb injectors, 80 mm mass air, 255 fuel pump, flowmaster cat back, bbk long tubes and h pipe 299.3 hp, 355.5 tq(before h-pipe, headers) Ricer Hater's Club-member #16

06-29-2002, 11:17 PM	#4
keakua Registered Member Join Date: Jun 2002 Location: phoenix, az Posts: 20	i run an A-trim with the S-trim impeller upgrade (still an A-trim housing). i put on the 2.95" pulley and was getting around 10-11 psi in hot weather with the crappy stock plastic intake hose and no bypass. i just put on a 10 rib 2.5" pulley, race bypass, and intake tube i cut and made for about $30. just got it running last week, so no dyno, but so far its putting out a little over 18#s. if you do get a smaller pulley or even keep the one you got, shot peen the surface that the belt touches to make it a little more abrasive and you can gain boost by preventing slipping at high rpm. its not bad for the belt at all, and the crank pulley i got from vortech for the 10 rib was already done, dont know why they dont catch on and do the blower pulley __________________ 88 Conv Vortech S-trim 2.5" 10-rib pulley, 332 stroker w/ Cat forged crank, forged JE flat-tops, forged rods, 10.25:1 comp, DSS girdle, edelbrock heads, Omega valvetrain, Lunati custom cam, extrude honed Cobra intake, 70mm T-body, Pro-M 77, bypass valve, dual Walbro 255 lph in tank pumps, an -8 fuel hose, aeromotive fuel rails/regulater. 42# inj, MSD ingniton/boost retard, JBA headers, flowmasters, full Griggs GR-40R suspension (K-member, torque arm, panhard bar, subframes, strut brace) Centerforce clutch, Tremec, Auburn posi locker, moser axles, Baer brakes/rotors, 17" cobra R wheels, custom body/roll bar

06-29-2002, 11:33 PM	#5
1995MGTS Registered Member Join Date: Mar 2001 Location: Chesapeake, VA USA Posts: 69	To answer your question, no, I didn't have the powerpipe yet. After putting the powerpipe on and correcting for the spark blowout (gapping the plugs to 0.35), I was able to pull to about 6200rpm. The powerpipe shifted the curve to the right. I'm assuming your gains with the A-trim might be similar. Here are my last three dyno pulls with the powerpipe: http://www.msnusers.com/MustangMembe...hoto&PhotoID=7 __________________ 2003 Redfire Cobra #5978 of 8394 -Pro-5.0 -DC cai -Steeda x-pipe w/cats -Steeda cat-back -Lightning pulley w/Afterburner 441rwhp/434rwtq SAE

06-30-2002, 08:13 PM	#6
rbatson Guest Posts: n/a	I did the crank pulley on mine for warranty reasons. Take the pulley off the blower and it voids your warranty.

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