78GTS vs. PT88 Dyno overlay inside on same motor
02-05-2009, 07:35 PM
#22
06-11-2010, 10:05 AM
#25
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i am to wondering why the gts fell off so hard?? what kind of cam are you running or close to if your secret on the specs? maybe adjusting the cam to the gts would be perfect?
btw, is there a big difference between an lt1 and ls1 when it comes to cams?
edit: thanks OP, prob the best apples to apples thread since ive been on here. can't wait to see the twins
btw, is there a big difference between an lt1 and ls1 when it comes to cams?
edit: thanks OP, prob the best apples to apples thread since ive been on here. can't wait to see the twins
06-12-2010, 04:04 PM
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Cam was a 224/224 .575 .575 115lsa, the 78mm turbo was huffing pretty good, right around 23psi which is pretty hefty in the upper RPM range, I think the hot side was the restriction because with the same settings on the eboost 2, the pt88 made more boost from my command to hold pressure on the top side of the wastegate. the gts was likely seeing some pretty high turbine inlet pressures and pushing open the wastegate.
The new setup I'm putting together is completely different, it will be twin ball bearing 67mm turbos with a different cam and a single plane intake manifold. Several other changes have been made as well to strengthen the bottom end and improve the oiling system. The original motor was losing oil pressure in the upper RPM range and I have done everything in my power to figure it out. I believe tapping the turbo feed at the oil filter adapter housing was a poor choice but i got away with it on the 78gts because the center section was a bit more restricted than the pt88. as soon as i put the PT88 on the car my oil pressure instantly showed 20psi lower at idle sitting around 18psi hot. The bearings eventually went south and I pulled the motor to regroup. I had every intention of going to an LS based setup, but in the end to achieve my goals on the lowly LTx platform nagged at me enough to give it one more shot. Hopefully the new Callie Billet main caps will add some rigidity and instead of a splayed cap setup from an f-body block, I am switching back to my factory LT4 straight 4 bolt main block. A better oil pan, pump and pickup will be used in conjunction with the block having the oiling system gona through by a trusted machine shop to optimize the galleys and prepare it for high RPM and better oil flow where it is needed.
I want to lengthen the powerband 1000-1500 RPM and see if I can get the power to work for me a little longer in each gear. Its a pain in the *** to shift so frequently just when it starts feeling good!
Hopefully the new setup will be back in action toward the middle of July, I have everything here for it and the motor is all but assembled. I'm finally getting pretty excited about the car again and hopefully I can get the combo where it should be and hit my goals of 1200rwhp on a 355 LTx platform. then I will turn the boost down maybe put some smaller turbos on it and hit the road course some!
Chris
The new setup I'm putting together is completely different, it will be twin ball bearing 67mm turbos with a different cam and a single plane intake manifold. Several other changes have been made as well to strengthen the bottom end and improve the oiling system. The original motor was losing oil pressure in the upper RPM range and I have done everything in my power to figure it out. I believe tapping the turbo feed at the oil filter adapter housing was a poor choice but i got away with it on the 78gts because the center section was a bit more restricted than the pt88. as soon as i put the PT88 on the car my oil pressure instantly showed 20psi lower at idle sitting around 18psi hot. The bearings eventually went south and I pulled the motor to regroup. I had every intention of going to an LS based setup, but in the end to achieve my goals on the lowly LTx platform nagged at me enough to give it one more shot. Hopefully the new Callie Billet main caps will add some rigidity and instead of a splayed cap setup from an f-body block, I am switching back to my factory LT4 straight 4 bolt main block. A better oil pan, pump and pickup will be used in conjunction with the block having the oiling system gona through by a trusted machine shop to optimize the galleys and prepare it for high RPM and better oil flow where it is needed.
I want to lengthen the powerband 1000-1500 RPM and see if I can get the power to work for me a little longer in each gear. Its a pain in the *** to shift so frequently just when it starts feeling good!
Hopefully the new setup will be back in action toward the middle of July, I have everything here for it and the motor is all but assembled. I'm finally getting pretty excited about the car again and hopefully I can get the combo where it should be and hit my goals of 1200rwhp on a 355 LTx platform. then I will turn the boost down maybe put some smaller turbos on it and hit the road course some!
Chris
06-21-2010, 07:15 PM
#31
Thanks for sharing the results and info..
Is the car Manual or auto I read 2step and 2nd or 4th gear I didnt what transmission??
I'm going to start by build in a month or two Built 347ci H/C and Single 80 or 82 Turbo this is on my ZO6 I really hope I can reach 730-760rwhp on pump gas+meth 15-16psi and close 900rwhp race gas 20-21psi
I hope can hit full spool in under 4500rpm with M6 trans...
Is the car Manual or auto I read 2step and 2nd or 4th gear I didnt what transmission??
I'm going to start by build in a month or two Built 347ci H/C and Single 80 or 82 Turbo this is on my ZO6 I really hope I can reach 730-760rwhp on pump gas+meth 15-16psi and close 900rwhp race gas 20-21psi
I hope can hit full spool in under 4500rpm with M6 trans...
