wastegates and emap

88turboii · 04-13-2011, 07:16 AM

this is probably a stupid question, but i have been reading up on emap (pre-turbo exhaust pressure) lately and got to thinking.. on an internal wg setup, what stops this from opening your wastegate before target boost is reached? i figured this is not a problem on external wg, because usually they open against the flow of exhaust, and/or they have dual ports so boost pressure works to keep the valve closed before target boost is reached

im running a 60-1/p-trim S5 hybrid with the stock 6psi wg actuator. but im running 15 psi, so the emap at that level has to be like 15psi minimum, right? why doesnt it push open the 6 psi wg door and let all the exhaust out?

***TitaniumTT*** · 04-13-2011, 08:23 AM

Honestly, at 15 psi MAP it's probably closer to 30psi EMAP.

It's a function of a few things, the surface area on the actuator that's getting your 15 psi (pounds/SQUARE inch) is probably about twice that of your wastegate.

The flow of exhaust out of the wastegate is not going to be enough to divert ALL the gases away from the turbine wheel.

RETed · 04-13-2011, 04:22 PM

Wastegate spring

-Ted

88turboii · 04-17-2011, 12:39 PM

well i ordered a dual port wg actuator, im thinking with a dual port, the wg will be held shut by boost pressure as well as spring pressure

04-13-2011, 07:16 AM	#1
88turboii destroy, rebuild, repeat Join Date: Feb 2008 Location: Charleston, SC iTrader: (0) Posts: 395 Rep Power: 17	wastegates and emap this is probably a stupid question, but i have been reading up on emap (pre-turbo exhaust pressure) lately and got to thinking.. on an internal wg setup, what stops this from opening your wastegate before target boost is reached? i figured this is not a problem on external wg, because usually they open against the flow of exhaust, and/or they have dual ports so boost pressure works to keep the valve closed before target boost is reached im running a 60-1/p-trim S5 hybrid with the stock 6psi wg actuator. but im running 15 psi, so the emap at that level has to be like 15psi minimum, right? why doesnt it push open the 6 psi wg door and let all the exhaust out? __________________ 1993 RX-7 Touring MB, stockport 13B-REW, 9.4CR rotors, T04S 60-1/p-trim single turbo 1986 RX-7 Base project track beast Last edited by 88turboii; 04-13-2011 at 07:58 AM..

04-13-2011, 08:23 AM	#2
*TitaniumTT* Test Whore - Admin Join Date: Mar 2008 Location: Right Behind you son iTrader: (4) Posts: 4,581 Rep Power: 10	Honestly, at 15 psi MAP it's probably closer to 30psi EMAP. It's a function of a few things, the surface area on the actuator that's getting your 15 psi (pounds/SQUARE inch) is probably about twice that of your wastegate. The flow of exhaust out of the wastegate is not going to be enough to divert ALL the gases away from the turbine wheel. __________________ -The Angry Stig- DGRR 2009, 2011, 2012 & 2013 - Best FC DEALS GAP!! WOOHOOOO!!!!! 2015 Audi S4 - Samantha - Zero Brap S4 2004 RX8 - Jocelyn - 196rwhp, 19mpg fuel to noise converter 2000 Jeep Cherokee Sport - Wifey mobile - Now with 2.5" OME lift and 30" BFG AT KO's! So it begins 1998 Jeep Cherokee - 5 spd, 4" lift, 33" BFG's - Rotary Tow Vehicle 1988 'Vert - In progress 1988 FC Coupe - Gretchen -The attention whore BEAST! I'm a sick individual, what's wrong with you? I'm pure Evil I'm still insane, in the best possible way. I think Brian's idea of romance is using lube. Your rage caused the meteor strike in Russia. The Antichrist would be proud of his minion. You win with your thread. Most everything It's a truck with a steel gate on the back. Just a statement of fact Motec M820, AIM dash, ported 13B-RE Cosmo, 6-spd trans, 4.3 Torsen, custom twin wg fully divided mani, Custom 4" split into 2x 3" exhaust, Custom HMIC, Custom custom custom custom I like to welder stuff.... No Bolt-ons allowed. Dyno'ed @ Speed1 Tuned by me - 405rwhp on WG.... WM50 cuming soon. *-Angry Motherfcker Mode ENGAGED-**

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04-17-2011, 12:39 PM	#4
88turboii destroy, rebuild, repeat Join Date: Feb 2008 Location: Charleston, SC iTrader: (0) Posts: 395 Rep Power: 17	well i ordered a dual port wg actuator, im thinking with a dual port, the wg will be held shut by boost pressure as well as spring pressure