Ls3 NA Build For My Focus
03-12-2018, 09:45 AM
#21
I think we might be making progress...
Those springs included with the 255 TFS heads are pretty modest, at 400# open. These are the specs:
The spring Comp recommends for that cam is the 80540, which is 155# on the seat and 420# open - slightly higher, but that is at 7000rpm. If you are spinning 7500-8k, you would need even more. As for the exact spring pressure or part number to run, I have no idea and wouldn't be qualified to make that suggestion. I would get with a pro that spec's cams for the LS3 and ask their opinion.
You are not only on the ragged end of max lift (.624 lift on that cam vs .625 max on those springs), but also under recommended spring pressure for that cam at 7k RPM - let alone 7500+. The upgraded option spring for those heads would be a good place to start, PN: TFS-16306-16.
Those springs included with the 255 TFS heads are pretty modest, at 400# open. These are the specs:
Code:
Valve springs: Standard 1.300" O.D. dual spring (TFS-16904-16) 150lbs. @ 1.800" installed height 400lbs. @ 1.200" open 370lbs. per inch rate 1.075” coil bind, .625" maximum lift(OE style rocker arms)
You are not only on the ragged end of max lift (.624 lift on that cam vs .625 max on those springs), but also under recommended spring pressure for that cam at 7k RPM - let alone 7500+. The upgraded option spring for those heads would be a good place to start, PN: TFS-16306-16.
Code:
Option 1 1.300" O.D. dual spring (TFS-16306-16) 155lbs. @ 1.820" installed height 465lbs. @ 1.200" open 463lbs. per inch rate 1.100” coil bind, .650" maximum lift (roller rockers)
Last edited by Puck; 03-12-2018 at 09:53 AM.
03-12-2018, 10:06 AM
#22
I think we might be making progress...
Those springs included with the 255 TFS heads are pretty modest, at 400# open. These are the specs:
The spring Comp recommends for that cam is the 80540, which is 155# on the seat and 420# open - slightly higher, but that is at 7000rpm. If you are spinning 7500-8k, you would need even more. As for the exact spring pressure or part number to run, I have no idea and wouldn't be qualified to make that suggestion. I would get with a pro that spec's cams for the LS3 and ask their opinion.
You are not only on the ragged end of max lift (.624 lift on that cam vs .625 max on those springs), but also under recommended spring pressure for that cam at 7k RPM - let alone 7500+. The upgraded option spring for those heads would be a good place to start, PN: TFS-16306-16.
Those springs included with the 255 TFS heads are pretty modest, at 400# open. These are the specs:
Code:
Valve springs: Standard 1.300" O.D. dual spring (TFS-16904-16) 150lbs. @ 1.800" installed height 400lbs. @ 1.200" open 370lbs. per inch rate 1.075” coil bind, .625" maximum lift(OE style rocker arms)
You are not only on the ragged end of max lift (.624 lift on that cam vs .625 max on those springs), but also under recommended spring pressure for that cam at 7k RPM - let alone 7500+. The upgraded option spring for those heads would be a good place to start, PN: TFS-16306-16.
Code:
Option 1 1.300" O.D. dual spring (TFS-16306-16) 155lbs. @ 1.820" installed height 465lbs. @ 1.200" open 463lbs. per inch rate 1.100” coil bind, .650" maximum lift (roller rockers)
What do you think about installing a bigger rocker while im changing the srpings? a 1.8'1 should get me .660ish lift and the heads flow well to .700 lift.
03-12-2018, 10:41 AM
#23
Just caught that you did the trunion upgrade on your stock rockers, which should take care of the biggest issue with them. Honestly it would make financial sense to just install the proper springs and keep everything else the same for now. See how it does, then if you are still not happy you can step up to the 1.8 setup. You will likely see ~575rwhp with the proper springs, and even though it wont be your goal it will save you probably $1200+ vs the shaftmount setup...although even though your HR isn't dealing with crazy high spring pressures, at 7500+ RPM the shaftmounts are still FAR superior to a stud mount rocker.
Last edited by Puck; 03-12-2018 at 10:48 AM.
03-12-2018, 11:17 AM
#24
Contact Johnson and get their recommendation for max spring pressure on their lifter. Too much spring and you'll pump down the lifter even with the short travels.
Hydraulic roller is fine for a drag car. .625 lift is also plenty. A solid roller will definitely run better and allow you to run more lift, but for an extra $3000 I'm not sure you really need it.
Dustin Lee regularly takes his hydraulic roller LS engines over 8000 rpm with stock rockers and .625 lift.
For what it's worth, I think your valve events are all wrong. Is your intake manifold a short runner tunnel ram style? I think you need tighter centers and a much earlier IVC, even for high rpm.
Our stock bottom end LS3 with a Victor Jr intake and ported stock heads HP peaked from 7100-7400 rpm with a comp 239/251 on 110 installed at 108 with the Cadillac road race ceramic lifters and stock rockers. It made 528rwhp through a 6000 stall converter and a powerglide and 9" slicks.
I think something like 243/255 on 108+2 would work a lot better for you.
Hydraulic roller is fine for a drag car. .625 lift is also plenty. A solid roller will definitely run better and allow you to run more lift, but for an extra $3000 I'm not sure you really need it.
Dustin Lee regularly takes his hydraulic roller LS engines over 8000 rpm with stock rockers and .625 lift.
For what it's worth, I think your valve events are all wrong. Is your intake manifold a short runner tunnel ram style? I think you need tighter centers and a much earlier IVC, even for high rpm.
Our stock bottom end LS3 with a Victor Jr intake and ported stock heads HP peaked from 7100-7400 rpm with a comp 239/251 on 110 installed at 108 with the Cadillac road race ceramic lifters and stock rockers. It made 528rwhp through a 6000 stall converter and a powerglide and 9" slicks.
I think something like 243/255 on 108+2 would work a lot better for you.
03-12-2018, 12:43 PM
#25
Contact Johnson and get their recommendation for max spring pressure on their lifter. Too much spring and you'll pump down the lifter even with the short travels.
Hydraulic roller is fine for a drag car. .625 lift is also plenty. A solid roller will definitely run better and allow you to run more lift, but for an extra $3000 I'm not sure you really need it.
Dustin Lee regularly takes his hydraulic roller LS engines over 8000 rpm with stock rockers and .625 lift.
For what it's worth, I think your valve events are all wrong. Is your intake manifold a short runner tunnel ram style? I think you need tighter centers and a much earlier IVC, even for high rpm.
Our stock bottom end LS3 with a Victor Jr intake and ported stock heads HP peaked from 7100-7400 rpm with a comp 239/251 on 110 installed at 108 with the Cadillac road race ceramic lifters and stock rockers. It made 528rwhp through a 6000 stall converter and a powerglide and 9" slicks.
I think something like 243/255 on 108+2 would work a lot better for you.
Hydraulic roller is fine for a drag car. .625 lift is also plenty. A solid roller will definitely run better and allow you to run more lift, but for an extra $3000 I'm not sure you really need it.
Dustin Lee regularly takes his hydraulic roller LS engines over 8000 rpm with stock rockers and .625 lift.
For what it's worth, I think your valve events are all wrong. Is your intake manifold a short runner tunnel ram style? I think you need tighter centers and a much earlier IVC, even for high rpm.
Our stock bottom end LS3 with a Victor Jr intake and ported stock heads HP peaked from 7100-7400 rpm with a comp 239/251 on 110 installed at 108 with the Cadillac road race ceramic lifters and stock rockers. It made 528rwhp through a 6000 stall converter and a powerglide and 9" slicks.
I think something like 243/255 on 108+2 would work a lot better for you.
03-12-2018, 07:06 PM
#26
ModSquad
iTrader: (6)
At what rpm did you experience tire spin, to have to roll in slowly?
I don’t see tire spin on your graph.
I don’t see tire spin on your graph.
03-12-2018, 08:35 PM
#28
03-13-2018, 06:37 AM
#29
ModSquad
iTrader: (6)
03-13-2018, 08:14 PM
#31
ModSquad
iTrader: (6)
03-13-2018, 09:09 PM
#32
At partial throttle at 4500 rpms its making 210 hp or whatever but as soon as you floor it it makes way more than that and the tires spin. At that point it is probably making 450+ lbft which is what spins the tires. If i gradually roll into the throttle the tires dont spin.
03-13-2018, 09:27 PM
#34
ModSquad
iTrader: (6)
At partial throttle at 4500 rpms its making 210 hp or whatever but as soon as you floor it it makes way more than that and the tires spin. At that point it is probably making 450+ lbft which is what spins the tires. If i gradually roll into the throttle the tires dont spin.
And if you could make 450 ft. Lbs. that’s not enough torque to spin the tires on a dyno. Lots of guys make way more power than this, and don’t spin on the dyno.
I’m not trying to bust your *****, I’m simply trying to see into what’s going on here. Lots of questions asked to you in this thread that you didn’t answer.
03-14-2018, 03:16 AM
#37
Reading comprehension is not a strong suit for some of you. Why are you guys so hung up on the torque? The guy has repeatedly explained that it was not at wot and you can clearly see that it was not getting it til at least 6k or higher. He also explained that torque is not a concern and he wants it to make more hp and carry further. Do you guys honestly think this 376 is making 100ft lbs @ 3000 and 250ft lbs @ 4500 just because the cam is a little bigger than you're used to?? You'd probably have to pull 6 plug wires to accomplish that.. or not be on the throttle all the way! Puck made some great observations and seems to be headed in the right direction.
Bottom line is, op has a bad little bitch with more on the table. A 376 with a shelf hr making 550 to the tire through a high stall auto is no joke. Better hope you don't end up next to this thing with your big stroker
Bottom line is, op has a bad little bitch with more on the table. A 376 with a shelf hr making 550 to the tire through a high stall auto is no joke. Better hope you don't end up next to this thing with your big stroker
03-14-2018, 06:43 AM
#38
ModSquad
iTrader: (6)
Reading comprehension is not a strong suit for some of you. Why are you guys so hung up on the torque? The guy has repeatedly explained that it was not at wot and you can clearly see that it was not getting it til at least 6k or higher. He also explained that torque is not a concern and he wants it to make more hp and carry further. Do you guys honestly think this 376 is making 100ft lbs @ 3000 and 250ft lbs @ 4500 just because the cam is a little bigger than you're used to?? You'd probably have to pull 6 plug wires to accomplish that.. or not be on the throttle all the way! Puck made some great observations and seems to be headed in the right direction.
Bottom line is, op has a bad little bitch with more on the table. A 376 with a shelf hr making 550 to the tire through a high stall auto is no joke. Better hope you don't end up next to this thing with your big stroker
Bottom line is, op has a bad little bitch with more on the table. A 376 with a shelf hr making 550 to the tire through a high stall auto is no joke. Better hope you don't end up next to this thing with your big stroker
Still waiting on full throttle dyno chart....lol.
03-14-2018, 06:57 AM
#39
03-14-2018, 07:05 AM
#40
Teching In
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Even if he gets a WOT pull from 2k rpms the chart won't register until after the converter flash hooks up, so likely after 5k by the looks of it. This doesn't mean the engine doesn't make torque lower than that, only that because of the torque converter, you can't sample it on the dyno like you can with a manual transmission car. It would be like slipping the clutch until 5k.