Rotaryknight
Go Kart Champion
Thanks just emailed
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HYDE16 Reviews - GFB T9351 DV+ Diverter Valve Kit
- Thread starter HYDE161
- Start date
[FONT="]Hi guys, [/FONT][FONT="][/FONT]
[FONT="]I just wanted to clear something up about the DV+ spring being discussed at the moment. We have not changed anything in the DV+ kit or made any revisions to the production spring.[/FONT][FONT="][/FONT]
[FONT="] [/FONT][FONT="][/FONT]
[FONT="]We are however doing some testing and HYDE16 is helping us out with this at the moment, but testing and results at this point are not conclusive. [/FONT][FONT="][/FONT]
[FONT="] [/FONT][FONT="][/FONT]
[FONT="]The current DV+ spring (which hasn’t changed and isn't about to) provides the best throttle response – we spent a lot of time and testing on this spring initially during the DV+ development to confirm. Optimum throttle response however can sometimes lead to low RPM flutter (usually more common on tuned/modded K04 engines) which, whilst not detrimental to the engine or turbo, is sometimes deemed annoying and undesirable.[/FONT][FONT="][/FONT]
[FONT="] [/FONT][FONT="][/FONT]
[FONT="]The current DV+ certainly has the solution – if the flutter noise is an issue, simply removing the main spring (the short fat one, not the long, skinny one) will make the DV+ open and close the same way as the factory valve, which prevents the flutter. However, this forfeits the throttle response benefit (NOT the boost-holding ability though, that is independent of the spring).[/FONT][FONT="][/FONT]
[FONT="] [/FONT][FONT="][/FONT]
[FONT="]So, can you get rid of the flutter AND keep the throttle response? [/FONT][FONT="][/FONT]
[FONT="] [/FONT][FONT="][/FONT]
[FONT="]Well, this is a significant challenge, and one that may or may not be possible, because what the diverter has to do to improve throttle response (which is to only open when required, only as far as required, and only for as long as required, no more) is completely different to what is required to eliminate low RPM flutter (which is to open fully, and only close when the throttle is re-opened). It’s a bit like fitting a huge turbo, and then wanting it to spool up like the stock turbo – some objectives can’t always co-exist.[/FONT][FONT="][/FONT]
[FONT="] [/FONT][FONT="][/FONT]
[FONT="]What we are investigating is if it’s possible with the spring to have a suitable compromise between maximum response and minimum flutter. We know through testing done on other modified cars this is not always possible, especially with larger turbos and tunes that attempt to bring boost on aggressively at low RPM and small throttle openings.[/FONT][FONT="][/FONT]
[FONT="] [/FONT][FONT="][/FONT]
[FONT="]Anyway, we will continue to test and if a compromise is possible we’ll certainly make sure to let you guys know![/FONT][FONT="][/FONT]
[FONT="] [/FONT][FONT="][/FONT]
[FONT="]In the meantime, if low RPM flutter really does annoy you enough, try taking the main spring out and see if it satisfies your requirements.[/FONT][FONT="][/FONT]
[FONT="]I just wanted to clear something up about the DV+ spring being discussed at the moment. We have not changed anything in the DV+ kit or made any revisions to the production spring.[/FONT][FONT="][/FONT]
[FONT="] [/FONT][FONT="][/FONT]
[FONT="]We are however doing some testing and HYDE16 is helping us out with this at the moment, but testing and results at this point are not conclusive. [/FONT][FONT="][/FONT]
[FONT="] [/FONT][FONT="][/FONT]
[FONT="]The current DV+ spring (which hasn’t changed and isn't about to) provides the best throttle response – we spent a lot of time and testing on this spring initially during the DV+ development to confirm. Optimum throttle response however can sometimes lead to low RPM flutter (usually more common on tuned/modded K04 engines) which, whilst not detrimental to the engine or turbo, is sometimes deemed annoying and undesirable.[/FONT][FONT="][/FONT]
[FONT="] [/FONT][FONT="][/FONT]
[FONT="]The current DV+ certainly has the solution – if the flutter noise is an issue, simply removing the main spring (the short fat one, not the long, skinny one) will make the DV+ open and close the same way as the factory valve, which prevents the flutter. However, this forfeits the throttle response benefit (NOT the boost-holding ability though, that is independent of the spring).[/FONT][FONT="][/FONT]
[FONT="] [/FONT][FONT="][/FONT]
[FONT="]So, can you get rid of the flutter AND keep the throttle response? [/FONT][FONT="][/FONT]
[FONT="] [/FONT][FONT="][/FONT]
[FONT="]Well, this is a significant challenge, and one that may or may not be possible, because what the diverter has to do to improve throttle response (which is to only open when required, only as far as required, and only for as long as required, no more) is completely different to what is required to eliminate low RPM flutter (which is to open fully, and only close when the throttle is re-opened). It’s a bit like fitting a huge turbo, and then wanting it to spool up like the stock turbo – some objectives can’t always co-exist.[/FONT][FONT="][/FONT]
[FONT="] [/FONT][FONT="][/FONT]
[FONT="]What we are investigating is if it’s possible with the spring to have a suitable compromise between maximum response and minimum flutter. We know through testing done on other modified cars this is not always possible, especially with larger turbos and tunes that attempt to bring boost on aggressively at low RPM and small throttle openings.[/FONT][FONT="][/FONT]
[FONT="] [/FONT][FONT="][/FONT]
[FONT="]Anyway, we will continue to test and if a compromise is possible we’ll certainly make sure to let you guys know![/FONT][FONT="][/FONT]
[FONT="] [/FONT][FONT="][/FONT]
[FONT="]In the meantime, if low RPM flutter really does annoy you enough, try taking the main spring out and see if it satisfies your requirements.[/FONT][FONT="][/FONT]
John@Unitronic
Go Kart Champion
If I recall correctly, that piece maintains a 2.25" diameter. If so, yes, you can purchase our 2.25" to 2.25" DV Re-Route Coupler (UH009-IN2) a la carte, in addition to our DV Relocation Kit. We also have a 2.5" to 2.25" DV Re-Route Coupler (UH008-IN2) for intakes that are 2.5" in diameter, but it's not yet listed on the website. The standard coupler included is made to work with our Intake, which is 3" in diameter, therefore it's a 3" to 2.25" coupler included standard in each DV Relocation Kit.
I had a large amount of what i was considering flutter after installing DV+. I had a small amount previous to install. My noise was similar to a "whoochoochoochoo" made by a pigeon. After fixing a boost leak that would have affected the before and after DV+ install I have heard 0 flutter. I am not sure if this is the same flutter but it is literally 100% gone now that I believe I have boost leak fixed.
HYDE161
Go Kart Champion
Guys, just an update... Now that I had a TON of stuff sorted out on my car (manifold, ignition, tune, etc), I can now get back to properly testing these springs.
For the water meth guys out there, I have a theory. My current setup is the Unitronic DV relocation kit with GFB DV+. With the relocation kit, when the OEM "D" diverter valve or GFB DV+ unit opens to release boost, the pressure/air flows through a hose back to the turbo inlet coupler or "pre-turbo". Technically, this air has already flowed through the intercooler and sends somewhat of a cooler charge "pre-turbo" thus mixing with the ambient air charge coming through the intake (filter to turbo). At the turbo inlet, the ambient air gets hit with minimal amount of cooler air only when the diverter valve releases the post-intercooler boost.
With a post-intercooler water meth jet, during boost water meth is sprayed, cools the post-intercooler air charge and flows through the throttle body pipe, by-passes the closed diverter valve and flows through the throttle/manifold/cylinders.
-When the diverter valve releases the boost, do you think the cool air charge in the throttle body pipe (pre-throttle body) would be even cooler when the diverter valve opens and sends the water meth / boost to the turbo inlet?
-With the OEM "D" diverter valve possibly bleeding boost at higher boost pressures, do you think a tiny amount of water meth is being feed "pre-turbo"? While extremely minimal, I’m just gauging the effect of this as I have been told pre-turbo water meth could be damaging.
-Is the GFB DV+'s higher boost holding capabilities another benefit to preventing boost bleed with water meth systems feeding water meth "pre-turbo"?
For the water meth guys out there, I have a theory. My current setup is the Unitronic DV relocation kit with GFB DV+. With the relocation kit, when the OEM "D" diverter valve or GFB DV+ unit opens to release boost, the pressure/air flows through a hose back to the turbo inlet coupler or "pre-turbo". Technically, this air has already flowed through the intercooler and sends somewhat of a cooler charge "pre-turbo" thus mixing with the ambient air charge coming through the intake (filter to turbo). At the turbo inlet, the ambient air gets hit with minimal amount of cooler air only when the diverter valve releases the post-intercooler boost.
With a post-intercooler water meth jet, during boost water meth is sprayed, cools the post-intercooler air charge and flows through the throttle body pipe, by-passes the closed diverter valve and flows through the throttle/manifold/cylinders.
-When the diverter valve releases the boost, do you think the cool air charge in the throttle body pipe (pre-throttle body) would be even cooler when the diverter valve opens and sends the water meth / boost to the turbo inlet?
-With the OEM "D" diverter valve possibly bleeding boost at higher boost pressures, do you think a tiny amount of water meth is being feed "pre-turbo"? While extremely minimal, I’m just gauging the effect of this as I have been told pre-turbo water meth could be damaging.
-Is the GFB DV+'s higher boost holding capabilities another benefit to preventing boost bleed with water meth systems feeding water meth "pre-turbo"?
Last edited:
Cryptic19111
Go Kart Champion
The mixture that is sprayed would be completely evaporated by then anyways, so its nothing to worry about. I'd say the air will be cooler, but it's absolutely nothing like spraying pre turbo. In those cases, they are basically spraying liquid right into the turbo, your case, even if the thing was leaking, it would just be cool air
GunMetalGTI
Go Kart Champion
I just got mine in the mail today. Installing tomorrow if weather holds out.
GunMetalGTI
Go Kart Champion
Drove to and from work today which is about 50 miles total with a mixture of everything in between. I will just say I definitely noticed an improvement in the way that boost builds and holds and it actually holds noticeably higher where it was lacking before. Needless to say the the older piston part of the valve was definitely leaking or bleeding boost and a bit worn out. I also have zero flutter or pigeon sounds like some ppl previously described.
