Exhaust pressure, how big of a problem?
Exhaust pressure, how big of a problem?
first of. got a om602 that is about to get bigger elements in the pump, dieselmeken 7.5mm, the stock turbo gives on current setup 1.3bar.
reading about people like blacksmokeracing and other they take up the subject of exhaust pressure as something that limits their power.
how does that show, and does it damage the engine?
should i get a pressure meater?
--- om606 ---
blacksmoke have both supercharger and turbo, and the exhaust pressure limits them to around 500bhp.
a friend got a om606 with mynä 8mm that is dynoed to 530bhp at 3.5 bar of boost with a Garret super hx40 something. is there a risk there is a large exhaust pressure there to, wich will damage the engine?
---------------------------------
daily driver
w115 240d 72hp 3.07 rearend
w123 om602 turbo 200whp 7.5mm pump fivespeed 3.07 rearend
+ a few more.
mbturbo.com
swampmonkey
05-29-2013, 02:02 PM #1hey there.
first of. got a om602 that is about to get bigger elements in the pump, dieselmeken 7.5mm, the stock turbo gives on current setup 1.3bar.
reading about people like blacksmokeracing and other they take up the subject of exhaust pressure as something that limits their power.
how does that show, and does it damage the engine?
should i get a pressure meater?
--- om606 ---
blacksmoke have both supercharger and turbo, and the exhaust pressure limits them to around 500bhp.
a friend got a om606 with mynä 8mm that is dynoed to 530bhp at 3.5 bar of boost with a Garret super hx40 something. is there a risk there is a large exhaust pressure there to, wich will damage the engine?
---------------------------------
daily driver
w115 240d 72hp 3.07 rearend
w123 om602 turbo 200whp 7.5mm pump fivespeed 3.07 rearend
+ a few more.
mbturbo.com
![[Image: EMP.jpg]](http://i128.photobucket.com/albums/p169/turbo617/MercedesForum/EMP.jpg)
Too much exhaust pressure definitely holds you back-when my VNT was locked in place I couldn't get past 2,000rpm because of the exhaust pressure.
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
Simpler=Better
05-29-2013, 02:17 PM #2You can setup an exhaust pressure gauge easily. Just tap a line to the exhaust pre-turbo, feed it through some copper coils to cool the exhaust, then to a boost gauge.
Too much exhaust pressure definitely holds you back-when my VNT was locked in place I couldn't get past 2,000rpm because of the exhaust pressure.
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
both engines rev the whole way out without any noticable problem,
no other setback/problem?
"when your vnt was locked in place" VNT?
---------------------------------
daily driver
w115 240d 72hp 3.07 rearend
w123 om602 turbo 200whp 7.5mm pump fivespeed 3.07 rearend
+ a few more.
mbturbo.com
swampmonkey
05-29-2013, 03:49 PM #3so the problem is that it holds the rpm back?
both engines rev the whole way out without any noticable problem,
no other setback/problem?
"when your vnt was locked in place" VNT?
---------------------------------
daily driver
w115 240d 72hp 3.07 rearend
w123 om602 turbo 200whp 7.5mm pump fivespeed 3.07 rearend
+ a few more.
mbturbo.com
(05-29-2013, 02:17 PM)Simpler=Better You can setup an exhaust pressure gauge easily. Just tap a line to the exhaust pre-turbo, feed it through some copper coils to cool the exhaust, then to a boost gauge.good idea for a gauge there,
Too much exhaust pressure definitely holds you back-when my VNT was locked in place I couldn't get past 2,000rpm because of the exhaust pressure.
so what is too much back pressure, if you where making 3 bar boost how much back pressure would be safe?
(05-29-2013, 02:17 PM)Simpler=Better You can setup an exhaust pressure gauge easily. Just tap a line to the exhaust pre-turbo, feed it through some copper coils to cool the exhaust, then to a boost gauge.good idea for a gauge there,
Too much exhaust pressure definitely holds you back-when my VNT was locked in place I couldn't get past 2,000rpm because of the exhaust pressure.
so what is too much back pressure, if you where making 3 bar boost how much back pressure would be safe?
I think I hit 30psi when flooring it? I can't remember too well it was a few years ago. VNT=variable nozzle turbo, it cranks down the exhaust clearance to make the car build boost FAST.
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
Simpler=Better
05-29-2013, 08:27 PM #6I have no idea, I was doing an impatient test run after having the car down for months. From other's experience, your exhaust pressure should only be a few psi more than your boost pressure at the same time. Some people have had the exhaust pressure be less than boost-now that's a sweet spot
I think I hit 30psi when flooring it? I can't remember too well it was a few years ago. VNT=variable nozzle turbo, it cranks down the exhaust clearance to make the car build boost FAST.
Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
Back pressure to boost ideal is 1:1. But that is nearly impossible anyway you look at it. I think 1:1.5 is fine
'82 300D -3" straight pipe, ALDA deleted, 3in1 glowshift gauge, HX30, egr-less manifold, A/W intercooler
'14 Ram 6.7l cummins -G56 handshaker, wishing it was deleted
Same as a Vgt turbo or anything else with a variable size exhaust housing.
Back pressure to boost ideal is 1:1. But that is nearly impossible anyway you look at it. I think 1:1.5 is fine
'82 300D -3" straight pipe, ALDA deleted, 3in1 glowshift gauge, HX30, egr-less manifold, A/W intercooler
'14 Ram 6.7l cummins -G56 handshaker, wishing it was deleted
But its not uncommon for it to be much higher than boost pressure I have seen 20psi boost pressure with 40psi back pressure. in high RPM situations on other cars I have worked on
Get a boost gauge hooked up to the exhaust and monitor the pressures and log them on a note book rpm, boost pressure, back pressure that will give you a good under standing of what is going on. Then if its way to high you can tune the boost pressures and fueling to get to a safe comfortable medium.
If a turbocharger was 100% efficient the boost pressure and exhaust pressure would be equal! That just not going to happen but they can get close depending on rpm throttle position and load. You want it as close to 100% as possible at cruising speeds! I.E long trips on the highway for the best fuel mileage! But under hard acceleration it will be higher.
1987 300SDL 6spd manual om606.962 swap project
1985 300td euro 5spd wagon running
willbhere4u
05-31-2013, 11:15 AM #8If your turbo is running in its efficiency range exhaust pressure should be close to boost pressure maybe a little higher. 20psi boost 22 psi back pressure.
But its not uncommon for it to be much higher than boost pressure I have seen 20psi boost pressure with 40psi back pressure. in high RPM situations on other cars I have worked on
Get a boost gauge hooked up to the exhaust and monitor the pressures and log them on a note book rpm, boost pressure, back pressure that will give you a good under standing of what is going on. Then if its way to high you can tune the boost pressures and fueling to get to a safe comfortable medium.
If a turbocharger was 100% efficient the boost pressure and exhaust pressure would be equal! That just not going to happen but they can get close depending on rpm throttle position and load. You want it as close to 100% as possible at cruising speeds! I.E long trips on the highway for the best fuel mileage! But under hard acceleration it will be higher.
1987 300SDL 6spd manual om606.962 swap project
1985 300td euro 5spd wagon running
On the highway, I generally see about 2 more PSI of EMP than boost. I am going to upgrade to a 2256V soon, I am curious to see how that one does on the highway.
With the 2056V I have on my 616, I can get higher boost pressure than Exhaust pressure, say about 15 PSI of boost and 10 PSI of EMP. That ratio is effected by engine RPM and Fueling levels, so I get the best boost over EMP ratio with high fueling stating from a lower RPM and spooling up.
On the highway, I generally see about 2 more PSI of EMP than boost. I am going to upgrade to a 2256V soon, I am curious to see how that one does on the highway.
om616:
10mm MW pump on om616 and turboed, any modification internaly? oilsquirters etc?
finaldrive with that setup?
hoping to turbocharge my om616 but thinks it breaths a tad to much, 72bhp w123 engine quite worn with 3.07 finaldrive.
---------------------------------
daily driver
w115 240d 72hp 3.07 rearend
w123 om602 turbo 200whp 7.5mm pump fivespeed 3.07 rearend
+ a few more.
mbturbo.com
swampmonkey
05-31-2013, 04:28 PM #10thanks for many and good answers, will have to get a boost gauge to see the preassures, 7.5mm pump on the way, so probalby need an EGT gauge to.
om616:
10mm MW pump on om616 and turboed, any modification internaly? oilsquirters etc?
finaldrive with that setup?
hoping to turbocharge my om616 but thinks it breaths a tad to much, 72bhp w123 engine quite worn with 3.07 finaldrive.
---------------------------------
daily driver
w115 240d 72hp 3.07 rearend
w123 om602 turbo 200whp 7.5mm pump fivespeed 3.07 rearend
+ a few more.
mbturbo.com
(05-31-2013, 04:28 PM)swampmonkey thanks for many and good answers, will have to get a boost gauge to see the preassures, 7.5mm pump on the way, so probalby need an EGT gauge to.
om616:
10mm MW pump on om616 and turboed, any modification internaly? oilsquirters etc?
finaldrive with that setup?
hoping to turbocharge my om616 but thinks it breaths a tad to much, 72bhp w123 engine quite worn with 3.07 finaldrive.
No internal mods except for advancing the cam a few degrees, and modified prechambers. I am running as much as 20lbs of boost at times with this turbo.
It is in a 201 chassis with a 4 speed, and I think the rear end is around 3.08 or so, the car had an automatic originally, and they had a stiffer ratio than the manuals.
(05-31-2013, 04:28 PM)swampmonkey thanks for many and good answers, will have to get a boost gauge to see the preassures, 7.5mm pump on the way, so probalby need an EGT gauge to.
om616:
10mm MW pump on om616 and turboed, any modification internaly? oilsquirters etc?
finaldrive with that setup?
hoping to turbocharge my om616 but thinks it breaths a tad to much, 72bhp w123 engine quite worn with 3.07 finaldrive.
No internal mods except for advancing the cam a few degrees, and modified prechambers. I am running as much as 20lbs of boost at times with this turbo.
It is in a 201 chassis with a 4 speed, and I think the rear end is around 3.08 or so, the car had an automatic originally, and they had a stiffer ratio than the manuals.
The less backpressure the more goes through the engine^^
EDH_Performance
06-02-2013, 02:30 AM #12I have an small bmw idi diesel 1665 that i have an 11mm ve-pump and holset he2211 with 7cm exhaust housing...I have 1,5 bars backpressure and 2 bars boost, and i feel much more power with this turbo than the smaller he211 that the ratio was 1:1
The less backpressure the more goes through the engine^^
'82 300D -3" straight pipe, ALDA deleted, 3in1 glowshift gauge, HX30, egr-less manifold, A/W intercooler
'14 Ram 6.7l cummins -G56 handshaker, wishing it was deleted
EDH, that's pretty amazing you can get that kind of boost with that little back pressure! Very cool
'82 300D -3" straight pipe, ALDA deleted, 3in1 glowshift gauge, HX30, egr-less manifold, A/W intercooler
'14 Ram 6.7l cummins -G56 handshaker, wishing it was deleted
12 Guest(s)
12 Guest(s)