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HARROP TVS, What You Need To Know & FAQ

Old 08-23-2011, 11:17 AM
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ya its not really a boost problem as much as a setup/tune problem... alot of turbo guys are running alot more boost than the tvs guys
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Old 08-23-2011, 03:31 PM
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the bypass valve can be used to limit boost, the stock car is limited at like 12, if you get higher than that the bypass valve cracks open and bleeds some of the boost, preventing you from building more pressure, im just curious if anyone has done this to keep the tvs on pump gas. i dont want to wind her up to 7k to get power, id rather run the smallest possible pulley to get instant torque and hp, set the red line at 7k and limit her boost to 20psi. seems like it should be simple, seeing if its been done.
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Old 08-23-2011, 05:09 PM
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Its possible but it would take a lot of tinkering to get the exact PSI you like. The limit boost feature is not determined by setting a desired PSI. So it will take some playing around with to get the tune right.
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Old 08-23-2011, 05:11 PM
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I've always thought of doing that, but didnt want to give the bypass too much of a workout, you know?
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Old 08-23-2011, 05:18 PM
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Originally Posted by Pyros777 View Post
I've always thought of doing that, but didnt want to give the bypass too much of a workout, you know?
I honestly don't know how the stock tune pulls boost...Even though I have seen it in a log...

Stock Injectors Stock Pulley Stock Tune and all the bolt-ons - Saturn ION RedLine Forums
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Old 08-23-2011, 08:23 PM
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Originally Posted by zfissette View Post
the bypass valve can be used to limit boost, the stock car is limited at like 12, if you get higher than that the bypass valve cracks open and bleeds some of the boost, preventing you from building more pressure, im just curious if anyone has done this to keep the tvs on pump gas. i dont want to wind her up to 7k to get power, id rather run the smallest possible pulley to get instant torque and hp, set the red line at 7k and limit her boost to 20psi. seems like it should be simple, seeing if its been done.
i tinkered with the bypass and the m62...set it to about 4psi, needless to say, car was a pigdog with no boost haha, even wound out on the highway
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Old 08-23-2011, 08:44 PM
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Old 08-23-2011, 09:09 PM
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the torque curve and hp at rpm of the tiny pulley are great, but the big boost is too much for most motors, my car is my daily driver so i want power that doesnt blow my motor apart and butt dyno is the most important thing to me im a few tiny mods from maxing out the m62 on pump gas then its time to talk tvs and porting. if no one has done this yet, ill get with my tuner and see what we can do about it once the tvs shows up. of course at some point a small cvt in place of a snout is going to have to be a reality. its literally embarassing that it isnt already a standard feature on all superchargers.
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Old 08-23-2011, 09:20 PM
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If you have proper mods (I.E. ported head, full exhaust, and a custom tune) then you're motor will be fine. Opening up the motor and exhaust reduce pressure buildup by increasing efficiency. My TVS w/ a 2.7 pulley only hit 20psi
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Old 08-23-2011, 10:06 PM
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Originally Posted by WickedSS2005 View Post
If you have proper mods (I.E. ported head, full exhaust, and a custom tune) then you're motor will be fine. Opening up the motor and exhaust reduce pressure buildup by increasing efficiency. My TVS w/ a 2.7 pulley only hit 20psi
thats high mine with my 2.7 pre meth on an average day 70s would see 17.8- 18 peak boost. after meth and on a cooler night maybe 19. (stock head)
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Old 08-23-2011, 11:16 PM
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With your TVS? Granted, I was going from the stock boost gauge in March lol
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Old 08-24-2011, 07:15 AM
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Originally Posted by zrated89 View Post
thats high mine with my 2.7 pre meth on an average day 70s would see 17.8- 18 peak boost. after meth and on a cooler night maybe 19. (stock head)
It's very hard to compare boost readings between 2 cars even if they are running close to the same setup. Lots of factors to take into consideration.
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Old 08-24-2011, 08:05 AM
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I know that and wicked that was on my m62 with a 2.7 tvs is going on soon as my new ais trunk kit gets here on monday!
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Old 08-24-2011, 08:09 AM
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Originally Posted by zrated89 View Post
I know that and wicked that was on my m62 with a 2.7 tvs is going on soon as my new ais trunk kit gets here on monday!
Ok.

Figured it's good to mention anyways for any newbs that read this thread!
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Old 08-24-2011, 08:26 AM
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Just his elevation difference could be a huge factor
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Old 08-24-2011, 08:28 AM
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Originally Posted by zrated89 View Post
Just his elevation difference could be a huge factor
Yep.

For sure!
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Old 08-24-2011, 12:45 PM
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Originally Posted by RooTBeeR View Post
i tinkered with the bypass and the m62...set it to about 4psi, needless to say, car was a pigdog with no boost haha, even wound out on the highway
How did you accomplish that in HPTs?
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Old 08-24-2011, 01:20 PM
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I've never played with it, but isn't it this: LSJ Boost Bypass - HP Tuners Bulletin Board ?

Originally Posted by omega_5
It's on the top right side of the screen, under "Boost Control". There are two tables.... Desired Torque (or MAP) and Desired Torque (or MAP) S/S.
The tables will have an RPM axis going across the top, and gears 1-6 on the side. Earlier PCM's will have boost in this table (the ones labeled 'MAP')... but newer PCM's will have a torque number is ft-lb (the ones labeled 'torque').
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Old 08-24-2011, 01:25 PM
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the motor setup correctly with a good tune will be fine on a tiny pulley
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Old 08-24-2011, 03:57 PM
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Originally Posted by ebristol View Post
How did you accomplish that in HPTs?
this was like 3 years ago so i cant really remember, but i thought i just changed like 1-2 tables in the tq management...hell, tbh im no totally sure that i actually got it to sit at 4psi(on the stock gauge)...but im guessing that i just changed boost limit vs gear, all i really remember is that i was thoroughly disappointed with the power lol i couldn't hardly merge onto the highway or even pass anyone one haha
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Old 08-24-2011, 11:51 PM
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That seems right but not how its done in the GM tunes.

Idk
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Old 08-24-2011, 11:59 PM
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i wouldnt have a clue how the gm tune does it, ive never ran into that before
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Old 09-22-2011, 02:33 PM
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Originally Posted by Area47 View Post
something else to keep in mind. the tvs does not hit like the m62 on terms of instant torque. think of it like a big turbo. my guess is due to the rotating mass, and air volume moving in there. if you spin it high enough {above 7k} you can see some good power numbers. the power doesn't drop off like the m62 does either.
Has someone ever thought about the by-pass valve spring rate being too stiff on the TVS?
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Old 09-22-2011, 02:58 PM
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That post was from 2009. The TVS will hit like the M62 with a small enough pulley.
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Old 10-09-2011, 09:55 PM
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What have you guys been running as far as 1/8th mile times go? I feel like my times should be a lot faster
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