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-   -   part throttle boost (https://www.homemadeturbo.com/forced-induction-7/part-throttle-boost-86534/)

TorganFM 12-01-2007 02:01 PM

Re: part throttle boost
 
15psi at 1/2 throttle? My 14b doesn't even creep past 3psi at part throttle. That's funky dude.

b18. 12-01-2007 05:16 PM

Re: part throttle boost
 
Your turbo shouldn't be building boost at part throttle cruising.

I can't even think what would cause that, there shouldn't be enough gas to move it faster than the flow of the exhaust gas. When cruising it's just like an N/A car.

Can you give a bit more detail as to how Dodge controls the boost? Seems to be electronically gated but even then you wouldn't see massive boost at cruise or part throttle.

rsmith2786 12-01-2007 05:18 PM

Re: part throttle boost
 
I had a T3/T04E with a .48 exhaust housing on an LS and i would get 5 psi cruising at 1/2 throttle. I loved it. Driving up hills and passing on the highway was great.

-SKUM- 12-01-2007 06:05 PM

Re: part throttle boost
 
My brother in law had a srt4 and when he put his forge wg on his srt4 it would give him mad part throttle boost. But your srt has a knock sensor so if you get any kind of det your ecu will pull timing. But since you arnt really putting a huge load on your car I dont think it would be a big deal. The way we fixed this is we put a bigger turbo on the car and went with a external wg. (have you seen how small the stock turbo is? the wg port is tiny on the thing)

Atticus 12-01-2007 06:51 PM

Re: part throttle boost
 
is this cursing at a set speed or accelerating part throttle

Smith-02 12-01-2007 07:06 PM

Re: part throttle boost
 
stenseltizm definitely made several pounds of boost at less than half throttle, in a LS teg, with a hx35.

ghettoturbo 12-01-2007 08:18 PM

Re: part throttle boost
 
its really not a bad thing imho...boost=fun

trioskater 12-02-2007 03:45 AM

Re: part throttle boost
 
haha , ya boost is fun i was just curious... im not so much worried about it on my car, im more worried that im gonna be on my bike at 6k rpms and boost will start creeping... but ya it is no cruising, its during acceleration... and no it is not an electric gate...

fe3tcourier 12-02-2007 11:52 AM

Re: part throttle boost
 
it sounds like your wastegate boost source is on the engine side of the throttle, if this is the case, when you lift, will go low and close the wastegate INCREASING the boost in front of the throttle and thereby forcing it to flow more air to the engine.

think of the throttle like a divider of pressure, these figures are random and way off, but it will illustrate the point :

15psi, you lift to half throttle, you end up with 5psi in the intake manifold and 15psi behind it, but plenty of exhaust gas exiting the engine.

because the wastegate now sees 5psi, it closes and increases turbine speed to try and obtain 15psi BEHIND the throttle thereby potentially increasing it way above 15psi between the compressor and throttle.

i cant see any other way that would happen either unless you have it plumbed wrongly. fiy, i also have mine plumbed wrongly, and experienced a similar thing. i'll fix it as soon as i get back to my project.

if you have it plumbed correctly ... if your speed and therefore engine speed is increasing, then you could be outflowing the wastegate and building more boost that way i guess. either way, if its 15psi on the engine side, its sure as hell higher on the other side!

fred.

ghettoturbo 12-02-2007 12:11 PM

Re: part throttle boost
 

Originally Posted by fe3tcourier
it sounds like your wastegate boost source is on the engine side of the throttle, if this is the case, when you lift, will go low and close the wastegate INCREASING the boost in front of the throttle and thereby forcing it to flow more air to the engine.

think of the throttle like a divider of pressure, these figures are random and way off, but it will illustrate the point :

15psi, you lift to half throttle, you end up with 5psi in the intake manifold and 15psi behind it, but plenty of exhaust gas exiting the engine.

because the wastegate now sees 5psi, it closes and increases turbine speed to try and obtain 15psi BEHIND the throttle thereby potentially increasing it way above 15psi between the compressor and throttle.

i cant see any other way that would happen either unless you have it plumbed wrongly. fiy, i also have mine plumbed wrongly, and experienced a similar thing. i'll fix it as soon as i get back to my project.

if you have it plumbed correctly ... if your speed and therefore engine speed is increasing, then you could be outflowing the wastegate and building more boost that way i guess. either way, if its 15psi on the engine side, its sure as hell higher on the other side!

fred.

plenty of people have their wg signal line coming from the intake manifold. Who cares what the boost is at before the IM anyway. When you lift, the wg is going to close to try to maintain the same pressure no matter where the wg source is coming from, thats how it works. It is always trying to maintain the same boost pressure (whatever psi it is set for).



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