Dynosheet, need opinions!

[bmaxwell]

Yeah somethings up but timing is def not the issue.

V8 motors dont need alot of timing to make alot of power with a turbo.

All my tunes run 16-17 degrees timing max. Its not overly conservative its just safe and no need for more timing like a blower needs.

My 10psi tune made 490rwhp with 16 degrees timing, that was before the frpp manifold.

My first dyno pull at 16psi was rich and had 15 degrees of timing and made 585rwhp. Cleaned up the air fuel and added 2 degrees of timing from 15 to 17, Netted me 70rwhp gain on the second pull.

Damn thats some power lol

 

[JeremyH]

The wastegate signal is coming from the manifold, I'm going to get it retuned after I get the cams taken out and I'll mention it to the tuner. He's more of a blower guy than a turbo guy and that's probably why it's not as smooth as it should be

And heres your problem most likely, you need a pressure only source for the wastegate somewhere before the tb, not from the manifold. Right off the turbo's compressor housing is the best spot.

 

[AbdullaGT500]

Well the shop that did the install had it the same exact way on his car, which made 925 rwhp so I don't think that's the issue.

 

[JeremyH]

It is an issue! Especialy at lower boost level where you are close to the wastegate springs rating, it can cause boost flutter.

If you could look at your boost graph i bet you would see it and it damn well could be why your power is so wavy up top.


For optimal and accurate wastegate operation you need a pressure only source.

The manifolds volume and the intake valves opening and closing causes the boost reading to not be stable and flutter, which will in turn flutter the wg if you run off it. The boost/pressure off the turbo or pre tb piping is constant.

 

[Full_Tilt]

And heres your problem most likely, you need a pressure only source for the wastegate somewhere before the tb, not from the manifold. Right off the turbo's compressor housing is the best spot.

Thats completely backwards.
The most ideal place is the cold side charge piping, the turbo outlet is the worst because its not taking into account the increasing pressure drop across the intercooler as flow increases. The boost at the manifold will be significantly lower at higher flow rates than it is at the outlet compared to lower flow rates, so you will see the boost "sag" or drop-off as you rev the engine out.

The manifold is okay except there are some issues with an underside turbo and PTB where you could possibly overspin the turbo, but I dont see it being a common issue.
I suppose there is some possibility of spiking from resonance and reversion in the intake manifold, but I have never seen it happen, and Ive tuned a lot of cars using the manifold as the WG boost source.

If you want to eliminate it as a possibility put a barb on the cold side charge piping near the intercooler, thats the best possible location.

 

[JeremyH]

Using the manifold for wg operation is a thing of the past from factory boosted 4 cylinders for safety. I understand the concept of leaks and intercooler losses as to why people thought the manifold was the best spot, so you will see that boost level that the wg spring promises, but thats just the wrong way to do it. You want optimal wg operations and whatever boost that gets you at the manifold is what it gets you, it will tell you if you have leaks and how efficient your intercooler is. If you want a little more boost get a bc or go higher on the spriing. I personaly wouldnt eun off a spring since its less efficient and you get more power/spool with a boost controller.

The compressor housing is the best spot, period. It will yield the most accurate and repsonsive wastegate operation and is safer if there is boost leak. Too many variable anywhere else. If you tap the intercooler you have to deal with the air expansion, if you tap the piping and there is a leak in a coupler nearby it will effect it. And if you run any kind of boost controller you definetly need to use the compressor housing.

 

[Full_Tilt]

If you want to use an electronic boost controller to bandaid the problem of boost sag, then thats fine. But if youre running off the spring or using a MBC the only way you are not going to have boost falling off as the pressure differential increases is going to be tp have it after the intercooler.
Theres no reason why tapping into the charge pipe should be difficult, that kind of pressure is very easy to seal against either with some JB weld or by welding a bung on.

Id rather spend 5 bucks on a barb than 300 bucks on a finicky electronic boost controller that I constantly have to play with because it has no way of compensating for temperature or atmospheric pressure.

 

[AbdullaGT500]

I'm running off the wastegate spring right now, it's an 8.7psi spring and I don't plan on upping the boost anytime soon.

 

[JeremyH]

Wonder what thats for then. and yes they come like that.