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what’s an indicator that springs are weaker? I have btr cam and btr dual springs but my power drop off is rough. Anyway I can test this spring situation ?
No easy to do it on the car really.
Use a mic to measure your spring height installed at fully closed and fully open heights. Then remove one spring and test it at those heights. Compare those pressures to the minimum pressures required for your cam.
Other option is if you purchased your cam from a cool vendor (like BTR) you can call them and give them those numbers. Then they will test a set of their springs at those heights and give you the numbers. (they did for me anyway). But the only way to know for sure what YOUR Spring is doing is to test it yourself.
A drill press and bathroom scale works ok in a pinch if you have one that goes up high enough. You can also buy the correct tool or borrow it if you have shop racer buds.
I made (had a friend make for me) a digital test rig with an Arduino board and pressure sensors.
.96 ar on the hotside is kind of big for twins. I run on3 70/68 with .68 hot side ( originally had the .96 hot side ) and my turbos were laggy with the .96. I change to the .68 ar and the difference was night and day. I have power at 3000 rpm now, before it was coming in at 4000+
Id look into that.
with a smaller ar I might run into back pressure issues. What size engine are you running?
Probably making 600+ easy with a 427 NA. .96's aren't too large IMO. I was seeing similar spool times as him with a 8.9:1 5.3 on twin 72/68's. w .9x hotsides. I'd think a healthy 427 would light those off at 2-3k easy!
Are your wastegates and BOV "v-band? You can buy Vband block off's semi cheap on ebay. I'd get a set. Start with the BOV because it's easiest. Then block the WG's.
Have you tried simply adding more spring to the gate and BOV? Don't those units usually come with additional springs? Lets see some pictures of the WG and BOV.
Probably making 600+ easy with a 427 NA. .96's aren't too large IMO. I was seeing similar spool times as him with a 8.9:1 5.3 on twin 72/68's. w .9x hotsides. I'd think a healthy 427 would light those off at 2-3k easy!
Are your wastegates and BOV "v-band? You can buy Vband block off's semi cheap on ebay. I'd get a set. Start with the BOV because it's easiest. Then block the WG's.
Have you tried simply adding more spring to the gate and BOV? Don't those units usually come with additional springs? Lets see some pictures of the WG and BOV.
I'll get some pics when I get home. I did put a larger spring in the BOV, I'll test drive when I get home.
with a smaller ar I might run into back pressure issues. What size engine are you running?
My motor is a fully forged Eric K 383 stroker 9:1 comp. No issues here. Although all of my piping is 2.5" to the turbos and then true dual 3" all the way out
I run 3 pound springs in my 44mm waste gates and only put 10 psi back pressure on the top of them with the co2. So if the numbers are right thats only 13psi back pressure to create 17psi cold side pressure. ( although i could be wrong )
My motor is a fully forged Eric K 383 stroker 9:1 comp. No issues here. Although all of my piping is 2.5" to the turbos and then true dual 3" all the way out
I run 3 pound springs in my 44mm waste gates and only put 10 psi back pressure on the top of them with the co2. So if the numbers are right thats only 13psi back pressure to create 17psi cold side pressure. ( although i could be wrong )
This is probably NOT the problem but it happened to me so I though I'd throw it out there. I'd had a PT76 on my LT1 in my Z28. Then, when I swapped to the 5.3 I'd taken everything apart, and the hotside of course changed. So when it was all in place and the engine broken in, I decided to try some quick excursions into boost. To my dismay, it took a substantial amount of throttle to get boost and it never elevated past 12 psi at WOT. The same (turbo) setup, when I took it apart was 21psi. Confounded, I did all the diagnostics the guys have offered but never found a cause. Then, when I was putting my tools up and picking up stuff in the shop, I came across the 'fire ring' for the Wastegate. I rolled my eyes and cursed. Put the car back on the ramps, pulled the waste gate off and inserted the fire ring. Afterwards the boost was back.
This is probably NOT the problem but it happened to me so I though I'd throw it out there. I'd had a PT76 on my LT1 in my Z28. Then, when I swapped to the 5.3 I'd taken everything apart, and the hotside of course changed. So when it was all in place and the engine broken in, I decided to try some quick excursions into boost. To my dismay, it took a substantial amount of throttle to get boost and it never elevated past 12 psi at WOT. The same (turbo) setup, when I took it apart was 21psi. Confounded, I did all the diagnostics the guys have offered but never found a cause. Then, when I was putting my tools up and picking up stuff in the shop, I came across the 'fire ring' for the Wastegate. I rolled my eyes and cursed. Put the car back on the ramps, pulled the waste gate off and inserted the fire ring. Afterwards the boost was back.
I've been thinking the same thing as it has happened to me before. CHECK THE FIRE RING!!!!
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