SLOW BOOST...Are my turbos mismatched?
SLOW BOOST...Are my turbos mismatched? Ok I spent all day today at the dyno for the first time with my new setup.
Forged 370 with AFR 225 heads and vic jr.
Twin GTK 650's. (66mm turbos with .68 exhaust housings)
Twin Tial 38mm wastgates with 10 lb springs.
Turbosmart Eboost Street Electronic boost controller.
My problem: Car makes power and boost but the boost curve is very slow and never flattens out. We were raising the boost on the controller and not seeing any more power. Just unsure of why it wouldn't hit 15 lbs quicker and then flatten out. Any ideas or things I should check that you can think of? We are concerned that turbos are mismatched or wastegates are never completely shut and is always leaking some boost by.
Forged 370 with AFR 225 heads and vic jr.
Twin GTK 650's. (66mm turbos with .68 exhaust housings)
Twin Tial 38mm wastgates with 10 lb springs.
Turbosmart Eboost Street Electronic boost controller.
My problem: Car makes power and boost but the boost curve is very slow and never flattens out. We were raising the boost on the controller and not seeing any more power. Just unsure of why it wouldn't hit 15 lbs quicker and then flatten out. Any ideas or things I should check that you can think of? We are concerned that turbos are mismatched or wastegates are never completely shut and is always leaking some boost by.
Both turbos have open 3" downpipes that are only about 5' long each...I'm sure there is some pressure drop but I don't think there are any leaks..no play in turbos they are brand new
On The Tree
Joined: Nov 2004
Posts: 199
Likes: 0
how much exhaust back pressure are you making before the turbo at the exh turbine inlet.
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I took both wastegates off and checked diaphragms and springs and everything looks fine...how do I ensure the gates are staying closed until desired boost is reached?
Before you get to carried away take it to the track and get some logs. I think you will see it spooling better at the track. On the dyno most people dont heat the turbo up before making the pull this leads to a lazy spooling. At the track the burnout heats the turbo up. Also on the valve springs you have .650 lift springs with a .580 lift cam. you need to shim the springs up to keep them close to coil bind and get more seat pressure.
In summary get your *** off the computer and get to the track.
In summary get your *** off the computer and get to the track.
That setup should spool really fast. Do you have any screen shots of the logging software that you are running against these pulls? Would be nice to see a boost or MAP curve to see what is happening where. Sounds like either the WG's are cracking open on you or the BOV. Put about 20 psi of regulated shop air to the top of the gate and watch carefully bring it up making sure not to over boost. You can do the same to the BOV without the overboost concern.
Before you get to carried away take it to the track and get some logs. I think you will see it spooling better at the track. On the dyno most people dont heat the turbo up before making the pull this leads to a lazy spooling. At the track the burnout heats the turbo up. Also on the valve springs you have .650 lift springs with a .580 lift cam. you need to shim the springs up to keep them close to coil bind and get more seat pressure. In summary get your *** off the computer and get to the track.
I am taking it to the track tomorrow and hopefully I can log a couple of runs...Also, I am unfamiliar with shimming valve springs. Are you saying I would be better off running a spring with a .600 to increase the seat pressure. Thanks for you help.
That setup should spool really fast. Do you have any screen shots of the logging software that you are running against these pulls? Would be nice to see a boost or MAP curve to see what is happening where. Sounds like either the WG's are cracking open on you or the BOV. Put about 20 psi of regulated shop air to the top of the gate and watch carefully bring it up making sure not to over boost. You can do the same to the BOV without the overboost concern.
AFR Dual Springs are junk. Even at 600 rwhp (boosted).
Swapped them out with PRC extremes, problems gone. KWIKKAR had the exact same issue on his APS SS and made right at 1000 rwhp on 19 lbs.
Although it does sound like you have a leak somewhere
-W
Swapped them out with PRC extremes, problems gone. KWIKKAR had the exact same issue on his APS SS and made right at 1000 rwhp on 19 lbs.
Although it does sound like you have a leak somewhere
-W