Weird Dyno numbers on 383 lt1
08-24-2018, 04:08 PM
#23
you are down minimally 50 HP/TQ. If the motor is mechanically sound and ignition and fuel systems working right and the cam was installed right.....that really only leaves the tune or the dyno itself is just way off.
Man for $150 you could get a mail order tune for the build. Would be very interesting if you then had more HP on a dyno with that tune...
Mustang dyno are known to show lower #'s...but your report says DynoJet which is regarded as the "better" one
Man for $150 you could get a mail order tune for the build. Would be very interesting if you then had more HP on a dyno with that tune...
Mustang dyno are known to show lower #'s...but your report says DynoJet which is regarded as the "better" one
08-24-2018, 04:32 PM
#24
you are down minimally 50 HP/TQ. If the motor is mechanically sound and ignition and fuel systems working right and the cam was installed right.....that really only leaves the tune or the dyno itself is just way off.
Man for $150 you could get a mail order tune for the build. Would be very interesting if you then had more HP on a dyno with that tune...
Mustang dyno are known to show lower #'s...but your report says DynoJet which is regarded as the "better" one
Man for $150 you could get a mail order tune for the build. Would be very interesting if you then had more HP on a dyno with that tune...
Mustang dyno are known to show lower #'s...but your report says DynoJet which is regarded as the "better" one
08-24-2018, 04:54 PM
#25
well your lifters could need replacing but if they were not pumping oil or holding pressure the car would really be missing and stumbling.
valve springs that are worn or just not up to the cam can have a feeling of just power stopped aka "nosing over" at 5k ish rpm. While the spec spring for the XFI is the 918 bee hive...maybe they are just not working as they should.
If doing new springs consider the Lunati kit. I have them with my XFI cam
valve springs that are worn or just not up to the cam can have a feeling of just power stopped aka "nosing over" at 5k ish rpm. While the spec spring for the XFI is the 918 bee hive...maybe they are just not working as they should.
If doing new springs consider the Lunati kit. I have them with my XFI cam
08-24-2018, 05:06 PM
#26
well your lifters could need replacing but if they were not pumping oil or holding pressure the car would really be missing and stumbling.
valve springs that are worn or just not up to the cam can have a feeling of just power stopped aka "nosing over" at 5k ish rpm. While the spec spring for the XFI is the 918 bee hive...maybe they are just not working as they should.
If doing new springs consider the Lunati kit. I have them with my XFI cam
valve springs that are worn or just not up to the cam can have a feeling of just power stopped aka "nosing over" at 5k ish rpm. While the spec spring for the XFI is the 918 bee hive...maybe they are just not working as they should.
If doing new springs consider the Lunati kit. I have them with my XFI cam
08-24-2018, 06:17 PM
#27
at 2k mi the 918's should be fine. If the heads did not have the spring pockets machined down than the 918's are installed short as stock spring height is 1.75x. So your coil bind is now shorter than spec then if the spring was installed at 1.800" as it should be. Your XFI has high lift. IDK if you are pushing to close to coil bind or not even if your springs are installed slightly short.
Either way just like worn out springs you would know at upper RPM's as the car would just nose over like it hit a 100 mph head wind
I assume the car runs like the dyno graph indicates...it just does not make any power above 5000-5200 rpm, right?
Either way just like worn out springs you would know at upper RPM's as the car would just nose over like it hit a 100 mph head wind
I assume the car runs like the dyno graph indicates...it just does not make any power above 5000-5200 rpm, right?
08-24-2018, 06:28 PM
#28
at 2k mi the 918's should be fine. If the heads did not have the spring pockets machined down than the 918's are installed short as stock spring height is 1.75x. So your coil bind is now shorter than spec then if the spring was installed at 1.800" as it should be. Your XFI has high lift. IDK if you are pushing to close to coil bind or not even if your springs are installed slightly short.
Either way just like worn out springs you would know at upper RPM's as the car would just nose over like it hit a 100 mph head wind
I assume the car runs like the dyno graph indicates...it just does not make any power above 5000-5200 rpm, right?
Either way just like worn out springs you would know at upper RPM's as the car would just nose over like it hit a 100 mph head wind
I assume the car runs like the dyno graph indicates...it just does not make any power above 5000-5200 rpm, right?
Last edited by Bosshog; 08-24-2018 at 06:42 PM.
08-24-2018, 08:23 PM
#29
I doubt coil bind is a issue although the slightly tighter installed height isn't helping. Perfect valve spring performance greatly supports valve train optimum performance. All valve springs are a "wear" item, especially with cams and higher revs.
Given the 918's have a short life expectancy before breaking (read YMMV) you should consider the Lunatti kit. It would be plug & play at the 1.75x installed height and work well with the XFI lobes
Given the 918's have a short life expectancy before breaking (read YMMV) you should consider the Lunatti kit. It would be plug & play at the 1.75x installed height and work well with the XFI lobes
08-25-2018, 12:48 AM
#30
I doubt coil bind is a issue although the slightly tighter installed height isn't helping. Perfect valve spring performance greatly supports valve train optimum performance. All valve springs are a "wear" item, especially with cams and higher revs.
Given the 918's have a short life expectancy before breaking (read YMMV) you should consider the Lunatti kit. It would be plug & play at the 1.75x installed height and work well with the XFI lobes
Given the 918's have a short life expectancy before breaking (read YMMV) you should consider the Lunatti kit. It would be plug & play at the 1.75x installed height and work well with the XFI lobes
08-25-2018, 09:52 AM
#32
08-25-2018, 09:54 AM
#33
….maybe a clue that shop does not have expertise in tuning the LT1 PCM
08-25-2018, 10:00 AM
#34
On The Tree
08-25-2018, 10:34 AM
#35
Village Troll 
iTrader: (2)
Exactly. LT1 PCM’s are extremely stable. It’s just that they’re slow and take several minutes to tune in what it takes seconds to do with a LS PCM, and shops today either do not own and/or are not familiar with LT software and don’t have the time or patience to **** with it.
08-25-2018, 01:45 PM
#39
Even If my car was untuned I would still expect it to put down more than 308 lol something just isn't right obviously . I don't think it's the tune.. you can clearly see that it looks to be like I have valve float issues but I just am not 100% sure..
08-25-2018, 01:45 PM
#40
TECH Junkie
