herbiemercman Posted January 23, 2020 Share Posted January 23, 2020 Hi Guys, I drove to an exhaust specialist this morning and i noticed a distinct lack of power. When the guy was fitting the front pipe to the 3" down pipe he noticed that the 8mm dia rubber pipe had fallen off the input nozzle at the base of the waste gate. He removed the pipe from the connection nozzle, located underneath the boost pipe where it joins the boost air output on the turbo. He showed me the pipe and it had a tight knot in the middle which to me was deliberate by "Rocket Dog" to blank off the connection to the waste gate? Does anyone know why they would do that? as this has been like this ever since the NAT conversion and the performance in general has been superb. Anyway the new pipe was fitted and routed correctly, connected to the boost air nozzle on the boost pipe where it joins the turbo, and the other end connected to the waste gate input nozzle.This now means that the waste gate is operating with pressure signals from the turbo end. The journey on the way home had the engine's power back? I would appreciate it if any member could explain this? The tuner at the exhast shop could not explain this and neither could my local garage owner who is well clued up on tuning. Herbie. 20200123_144314.jpg (431.6 KB) 20200123_144204.jpg (458.8 KB) 20200123_122212.jpg (509.5 KB) Quote Link to comment Share on other sites More sharing options...
Style Posted January 24, 2020 Share Posted January 24, 2020 I'm not sure I understand what's happened to be honest, but it sounds like you're saying the hose between the wastegate port and the turbo boost reference port was disconnected as well as being in a knot? Why I think I've misunderstood is because if that hose was either disconnected or connected with a knot in it, the car would actually make more power as the wastegate would have no boost input, leaving it shut and your turbo would just spool to the moon until something went bang. When your turbo reaches a certain boost pressure, that small hose opens the diaphragm inside the wastegate and diverts exhaust gasses around the turbo to prevent it from making any more boost. The point at which this opens is either controlled by a pressure rated spring inside the wastegate or a boost controller. Do you know if you have a boost controller fitted at all? Also, how many hoses are going to the wastegate? 1 or 2? Sounds like it's just the 1 hose and the boost is controlled by a spring. If I have understood correctly, then the only thing I can think of that's saved your skin is the exhaust gas pressure forcing the wastegate open which isn't really the way it's supposed to work. Quote Link to comment Share on other sites More sharing options...
Noz Posted January 24, 2020 Share Posted January 24, 2020 (edited) Have you spoken to Rocket Dog. If you've had a change since the visit then it's impossible to connect the two in my opinion. A recent change losing power couldn't be blamed on something done before there was an issue. I'd speak to him. I've never seen someone black off using a knot. That doesnt seem like a method to blank off Edited January 24, 2020 by Noz (see edit history) Quote Link to comment Share on other sites More sharing options...
herbiemercman Posted January 24, 2020 Author Share Posted January 24, 2020 Thank you style and Noz, basically Rocket Dog capped off the waste gate and the air pressure connection near the turbo, so all the knotted pipe could do is provide a complete blank off at each end. I have tried to contact Craig, (Rocket Dog), no reply as yet. My guess is that i just have a spring set up for 0.8 bar in the waste gate,just mechanical, and the back pressure from the exhaust opens the valve. Why blanking the pipe completely is seen to give better performance i do not know? Currently i have fitted a more robust new pipe connected at both ends, the car definately performs better than it did with the other pipe not being connected to the waste gate.? It is hard to see that the negative pressure/suction from my new pipe can operate a tiny bellows and help open the valve? Herbie. Quote Link to comment Share on other sites More sharing options...
Mike2JZ Posted January 24, 2020 Share Posted January 24, 2020 You should have two ports on wastegate, a lower and upper port. Please identify and say which port had the knot in. Or takes some better photos, cant tell anything from the ones you took Quote Link to comment Share on other sites More sharing options...
Style Posted January 24, 2020 Share Posted January 24, 2020 Have you got a boost gauge as well? Now that you've un-blocked the hose and ran it to the wastegate, you could now be running more boost than what you had before hence the better performance. Your car may not be mapped to run this higher boost however, so it's worth being a bit careful until you know what's happened. Start with Mike's request and go from there, that will be the best way of getting a starting point and we can go from there. Quote Link to comment Share on other sites More sharing options...
herbiemercman Posted January 24, 2020 Author Share Posted January 24, 2020 Many thanks, Mark and Style, There is only one connection on the lower side where the diafragm base is,and cannot get in to get better pics. The hypothesis my Merc tuning guy has is that Rocket Dog blocked off the pressure end near the turbo outlet and blocked the connection on the waste gate, with the internal spring being set at 0.8 bar, the surge back pressure when you lift of the throttle, would open the valve, just like the pressure relief valves you have on combi boilers. I do not know where i would get the best performane / boost, with the original Rocket Dog settings, all blocked off, or the current setting with the new pipe securely connected at both ends? Craig is very good with these cars and he must have done what he did for a good reason, all be it was a bit of "Heath Robinson", a knot in the pipe. Herbie. Quote Link to comment Share on other sites More sharing options...
Mk4Gaz Posted January 24, 2020 Share Posted January 24, 2020 If there's only one connection port, are you sure it's not a bov! Quote Link to comment Share on other sites More sharing options...
herbiemercman Posted January 25, 2020 Author Share Posted January 25, 2020 Hi Mk4Gaz, I have not heard of a BOV, (blow off valve) before, but it sounds like that is what it is? i am familiar with waste gate, screamer valve, and pressure release valve, however if a BOV has just the one connection what would be the reason for someone blanking it off? Herbie. Quote Link to comment Share on other sites More sharing options...
Noz Posted January 25, 2020 Share Posted January 25, 2020 A BOV is a dump valve herbie. Have a gander on YouTube for the explanation of both. It will help you understand the requirement for the ports. You need clearer photos of your wastegate. This is why I relocated my wastegate into the engine bay, as photos/issues are a pain with it under the car. Your photo sadly doesnt indicate make model or clear definition on any further available ports. Quote Link to comment Share on other sites More sharing options...
sidewaysdan Posted January 25, 2020 Share Posted January 25, 2020 (edited) Herbie That wastegate looks the same as mine. I believe dr-j used demon motorsport wastegate . Edited January 25, 2020 by sidewaysdan (see edit history) Quote Link to comment Share on other sites More sharing options...
herbiemercman Posted January 25, 2020 Author Share Posted January 25, 2020 (edited) Hi Dan, Good timely info, I am sure Craig (RDR) used a "Demon Motorsport" wastegate on my NAT build. I have just looked on their site and all the valves advertised don't have any pipe connections, so they must operate like a standard pressure release valve with an adjustable spring. Your valve seems to have two pipe connections, also i can only find the one connection on my valve, however it is connected to the manifold pressure and i have better performance than i had when the pipe had fallen off the valve? Maybe i could block off the pipe like RDR did and see if i get the same or better performance. I cannot see Craig RDR blocking both ends of the pipe without a good reason? he did lots of NAT builds and apart from bits and pieces, that where a bit tatty, the overall performance and his costs were very good, he was well clued up, he also gave good after sales service. Herbie. Edited January 26, 2020 by herbiemercman (see edit history) Quote Link to comment Share on other sites More sharing options...
Style Posted January 26, 2020 Share Posted January 26, 2020 You really need to get this car down to a tuner and looked at mate. You’ve got no idea how much boost you’re running with this hose on or off and the lowered compression ratio from the headgasket change at least needs a look at as well. Have you got a boost or Air/Fuel ratio gauge at all? They’re something to at least give us an idea if you’re ball park ok when giving the car a bootful or (chances are) running lean from any extra boost you may have added by connecting hoses up Quote Link to comment Share on other sites More sharing options...
Noz Posted January 26, 2020 Share Posted January 26, 2020 Style is right Making a change for performance and not monitoring the output is dangerous and can blow your engine. I wouldnt have changed anything personally without speaking to Craig. Its madness mate to take anyone's advice on here or even discussing it further without speaking to Craig and going over the situation. All speculation or fiddling does it delay resolution to your situation. Quote Link to comment Share on other sites More sharing options...
herbiemercman Posted January 26, 2020 Author Share Posted January 26, 2020 (edited) Hi Style and Noz, I have had a long conversation with Craig, (RDR), if you look at my latest thread you will see where i am heading. I think i tried to convince myself that there must be some thing wrong other than the reduction in CR and the BHP, i was convinced we must have set the ignition timing wrong, and then the blanked off pipe issue with the wastegate, then i had a boost pipe half off, etc. Anyway "the writing is on the wall now", i just have to shell out some big bucks and drive a long way form my home, to restore my situation, i just cannot enjoy the car until this is done. My boost gauge when i rev up only reaches the mark where negative pressure readings meet the positive readings, not sure why this is? You have both tried to help me and Mike 2JZ and Dan as well, and i will always appreciate that, the only good thing is that i have learned a lot about tuning, and how fickle it can be. Herbie. Edited January 26, 2020 by herbiemercman (see edit history) Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 30, 2020 Share Posted January 30, 2020 Hi Style and Noz, I have had a long conversation with Craig, (RDR), if you look at my latest thread you will see where i am heading. I think i tried to convince myself that there must be some thing wrong other than the reduction in CR and the BHP, i was convinced we must have set the ignition timing wrong, and then the blanked off pipe issue with the wastegate, then i had a boost pipe half off, etc. Anyway "the writing is on the wall now", i just have to shell out some big bucks and drive a long way form my home, to restore my situation, i just cannot enjoy the car until this is done. My boost gauge when i rev up only reaches the mark where negative pressure readings meet the positive readings, not sure why this is? You have both tried to help me and Mike 2JZ and Dan as well, and i will always appreciate that, the only good thing is that i have learned a lot about tuning, and how fickle it can be. Herbie. The gauge is doing this almost certainly because you are making no boost for whatever reason. It must be plumbed on the engine valve side of the throttle body to see vacuum, which is correct and normal for a vac / pressure gauge, and on wide open throttle it just sees near atmospheric pressure as there's no boost... Unless the gauge is buggered of course... Quote Link to comment Share on other sites More sharing options...
herbiemercman Posted January 31, 2020 Author Share Posted January 31, 2020 Hi Chris, You are right it was a boost issue, i found it today, large tear in the pipe which connects to the air intake, could not be seen as it was on top of the turbo fan scroll. Performance has now returned in full, but boost gauge still only measuring negative readings? Herbie. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 31, 2020 Share Posted January 31, 2020 raceparts.co.uk mechanical gauge and some rubber hose, sounds like the electronic gauge or sender, (assuming it IS electronic, I have never seen a mechanical one only read vacuum...), is kaput. Even cheap mechanical gauges are far more reliable unless you spend a LOT of dosh on a good electronic one Quote Link to comment Share on other sites More sharing options...
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