herbiemercman

The pipe goes from the boost pipe on the outlet of the turbo where i assume the highest pressure can be measured. Craig Allard (Rocket Dog Racing), the stage 1 builder blocked off the pipe in the middle so the dump valve was sealed and so was the output on the turbo boost pipe. He told me that is how he wanted it and the dump valve just relying on the pressure compressing the spring and opening, it worked very well. I tried fitting a new pipe with pressure readings being involved, but you could not see any difference in the performance etc. ? When my boost recovered and that just gave me a bigger exhaust system, lower CR, then the dump valve was sticking open, even on tick over? So i adjusted the spring a little and the valve was ok and brought back my spooling noise. Both Craig Allard, and i think Chris Wilson? did not think i would be running lean? I will still look for a re-map. Herbie.

Hi Guys, Yes it is a dump valve, spring set at 12PSI, i still do not know what the single little pipe connection does? With reference to the suggestion of having used just the one thread, i thought at the time that it would put things more clearly for the different problems that developed, and also i thought a new thread would get noticed more. Anyway there has been lots of help from you all and this has educated me and helped solve many of the issues. I am currently looking for a good mapper. Herbie.

Thanks guys, that makes a lot of sense, my problem is locating a mapper that will get involved with Greedy Emanage piggy backs, if there is one, then i know i would have to travel, all be it that would be ok. Just a point for Scooter, the performance post NAT was sharp and responsive at the bottom end, you just touched the accelerator, also the spooling noise was instant, NOT, half way down the accelerator pedal. I am still glad i have my boost back, and it flies when you put the boot down. Still no positive pressure readings on my boost gauge, just negative? Herbie.

Hi Guys, My boost has been restored by replacing a torn boost pipe and adjusting the wastegate spring, however one thing i do miss is the sharpness / torque i used to have at the initial accelerator pedal, basically i have to cross a sort of doseile initial pressing of the accelerator and get into the real boost, it is a sort of delay? Do any of you know why this has happened? The only thing that has changed from the original NAT build is the 3" Jap Parts exhaust system and a reduction of CR from 10to1, down to 9to1, and the adjustment of the wastegate to a higher release spring setting. ? Herbie.

Hi Style, Just seen your post and you are spot on, see my new thread, re, boost false dawn, it explains about the wastegate. Changing the subject, i have full boost back, BUT, the boost gauge is still only giving neg readings? My local mechanic came by with a boost gauge and this gave the same readings?, he moved the pressure pipe from the take off used for the boost MAP sensor, and connected it to the pressure sensor at the outlet on the turbo pipe, readings the same? surely not two faulty gauges? I am made up that my boost is back, but the boost gauge is a mistry. Herbie.

Hi Dudes, Many of you know i have been trying to resolve my loss of boost problem for the past two weeks and yesterday it was restored, lots of power and the spooling noise from the wastegate screamer valve. When i returned home after my test run, full of joy, i could hear a noise like the exhaust was blowing, on investigation i traced it to the down pipe connection on the turbo. I then realized that the garage who fitted my new exhaust "Jap Parts" system must have disturbed the joint when they connected the front pipe. Today i remade the joint and found out that the exhaust garage had not replaced the down pipe retaining bracket which bolts to the gearbox, they had also used just silastic on the joint instead of exhaust putty. So i sorted all this out and started the engine, it sounded like a tractor and i thought i had left an exhaust leak, all be it i could not see why, i did a good job? Anyway there was no exhaust leak BUT my discharge pipe on the wastegate was my new exhaust pipe? Yes so i figured out what had happened, the return of full boost coupled with the new free flow exhaust system necessitated adjustment of the the wastegate spring, Craig RDR warned me that this might happen. So i adjusted the setting until the vale closed on tick over, the tractor noise stopped and i went for a test drive,full boost restored and my spooling noise back, so another celebration. These NAT cars are not for the faint hearted i have twice nearly "set fire" to mine. Herbie.

Hi Swampy, I learned from the situation in that i now realize that just looking at the boost pipes and pulling them is not enough to find a boost leak. The leak that was causing my problem was hidden underneath the turbo housing, so this tells me you have to remove the pipe connections and examine the silicone rubber connectors, They are designed to withstand 185 deg.C.and what caused a 75mm tear is beyond me? Herbie.

Hi Swampy, Yes i know that, but,be honest, who would look under the pipe where it was tight up against the top of the turbo. However i have learned a lot and it is hard not to check all the things you are being advised by experienced people. Also i had reasons at the time for thinking i had lost a lot my power due to the CR reduction from the head gasket, the timing, boost controller connections etc. Herbie

Hi Dudes, Yes i am having a "Boost" celebration as i have been struggling with mega power loss for weeks thinking it was my new cylinder head gasket thicker and more robust, but reducing my CR from 10to1 to 9to1. Estimates from the club were circa an estimated loss of 50BHP? also some said it would be much less, very little? Today after looking at all my boost pipe connections which looked ok, i decided in rage to just remove all the system, and low and behold i found a large tear in the pipe which connects to the air intake manifold. The tear was between the underside of the pipe and the top of the trubo fan scroll, impossible to be seen, even if you carried out the blanking test to see if the engine stopped, you would still find it difficult to locate this leak. Anyway my performance is fantastic, just like the original NAT build, and i have a head gasket which should last longer. My boost gauge is still only measuring negative readings so i think this needs changing, this made my investigation hard work, i do not think it ever gave + positive readings. Many thanks to all who tried to help, i have also learned a great deal from this problem, all the twists and turns, was it the boost? or was it the CR down? was it the ignition timing, was it the wastegate stuck open, was it the MAP pressure readings connection?, yes it was a frustrating time, but i great feeling at the end. Herbie.

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.

Boost now ok, it was a badly torn pipe above the turbo on the air intake manifold. Performance fantastic, but gauge still reading only negative readings, time to replace it. Herbie.

Hi Chris, Your posting must have given me the "Midas" touch, after examining all my boost pipe connections, which looked ok, i then removed all the pipe system, what a relief i found! The pipe which connects to the air intake manifold had a 3" tear in it, a mega boost loss. I replaced the pipe and the performance came back to the best it has been since the original NAT build. Contrary to the advise i was given on how much BHP i would lose on the CR of the thicker gasket, you were correct stating the reduction would be minimal. For three weeks i have been struggling and had lots of support and help from the club members, some were addament about finding the boost leak, but it was well hidden, also it did not help that the boost gauge was not working, and still is not working. Even if i did the capping off the turbo intake test to see if the engine stopped, it would still leave me trying to locate the leak, i only found it today because i threw the pipes off in rage. I was close to contacting you and paying a visit to Nantwich. Herbie. (Adrian's Brother).

Thanks for comments guys, do any of you know where the sensor is located? boost pressure is + positive, so why are my readings negative, this suggests the sender is on the air intake side, not the boost side?, having said that i guess the readings could be negative until the turbo cuts in, then the readings would go + positive. Hi Noz, I am at my friends garage tomorrow where we can check the boost system from his ramp, the ones not inside the engine bay are not visible unless you get under the car. I have had the boost pipe blow off twice until i realized that the guy who assembled it used silicon grease to push the pipes on more easily, problem being they can then slip off. I do not expect to find a boost leak, more likely the wastegate for some reason is sticking open? Herbie.

Hello Dudes, My Boost gauge is only measuring and showing negative pressure readings? , to be honest in the past i have only payed attention to my oil temperature gauge, so it is possible the gauge or it's sender has never worked correctly? They are only low cost items and i have no means of testing it, i am only bothered about the performance as i think i have a boost problem. Some one may know if these gauges can have the situation i have, if it is unlikely and it is telling me there is a boost problem? My view is that if the gauge can register negative pressure, then it should be able to register positive pressure readings? Herbie.

Maybe i should have retained the 0.6mm gasket and consequently would have retained my CR and performance, however at the time i was so pissed off with the gasket failure, pluming, water loss, overheating etc., that i wanted something to stop this happening again, which was the 5 laminate 1.3mm robust gasket. To be honest i like having this back up, as the replacement gasket job is a nightmare and £1,000 DIY job. I have still not found out what the true performance loss is? as many members in good faith give different quotes on this, i can not say until i sort out my boost issues. They say if you do not get problems you will not learn, BUT i would sooner not have the problems. lol. Herbie.

Hi Noz and Adam, I realize you are right re take car to a qualified tuner, they are all many miles away and Craig RDR is 500 miles there and back, you also have to leave the car for a few weeks. This is why i must bottom whether i have a boost issue like the last two posts are telling me. I accept i have been all over the place with the problem but that is how it has unfolded. I am grateful for your help, and hope you can see i must soldier on. I do have a final solution backup in place, recently agreed with Craig RDR, if i need it? Hi Style and Shane, Thank you for your comments, i will try the turbo idea. Hi Suprakeith, I purchased new HT cylinder head bolts. Herbie.

Hi Noz, I am sorry i am having to be qualative and not quantative but i have not had a choice, most of my details have been supplied by the guy that did the build, Craig (RDR), also my boost gauge is only registering negative pressures. Following the head gasket job the and the reduction in CR, the only other issue, at the time was not being sure about the ignition timing, RDR said it was set at 8 degBTDC and the MAP takes care of it. So i noticed the reduction in performance and started enquiring on the site what i could do about it? The answers were bigger injectors 550cc, bigger fuel pump and increase the boost, and re-map, it made sense and i just spent a couple of weeks thinking about it, cost? who could do it,etc. Meanwhile i decided to change the stock exhaust system for a 3" Jap Parts free flow system, and the mechanic found the air pipe missing from the bottom of the wastegate and then the knott in the pipe. Craig DR said he wanted the pipe blocked at each end and was just running a wastegate spring gate at 12 PSI, he said the new exh would not affect the AFR and would not lean out, but he thought the exh would cause the wastegate to open too early and consequently reduce the boost considerably? Should i block off my pipe as per RDR? as it is now connected at both ends? I have looked at all the boost pipe connections and all look ok, could it be the problem all along is the wastegate loosing the boost.? What do you think? Herbie.

Hi Swampy & Adam, I have had my engine from new 42,000 miles back, so you can understand this is a good base for me, not a GTE, i just "fuc--d up" the stage 1 conversion with a head gasket mistake. Soon it will be sorted and i should end up with even better performance. Herbie.

Hi Dan, That is very good of you re the pump, the job now in hand is at an agreed price with parts, labour and a re-map. Herbie.

Hi Turtleshead, Not sure where you got your believe info from? The build was great as promised, ran great for 3 years, it was my fault i had problems which i explained in my posts if you read them, the thicker head gasket was the problem, NOT the build it was good value for money, if you did the same to a top market build, the head gasket would cause a problem. I have found a way out of the problem, just adding improved fueling and more boost, i will also get benefits that the stage 1 did not give. Herbie. (The OP).

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.

Hi Dudes, I had a fantastic NAT build with circa 400BHP and the torque to go with it, also it had a great spooling scream coming from the wastegate. So the stock head gasket,0.6 mm thick, failed on the no 1 cylinder and had to be replaced, very stressful job and expensive. I chose the TT thicker gasket at 1.3mm thick, six ply, much more robust and the stock ones are prone to failure. At the time i did not realize how much this change would compromise my engine's performance. The CR dropped from 10 to 1, to 9.5 to 1, this does not seem significant to the uninitiated like me, BUT i lost 25% of my BHP. If you are used to a certain power level, then the big power reduction is very noticeable. To restore the power i will have to shell out for bigger 550cc injectors, larger fuel pump and increase the wastegate boost spring, or buy an electronic boost controler, with labour and the re-mapping we are looking at big bucks. So if your head gasket fails and you only want to do the job once with the thicker 1.3mm gasket, then your looking at big bucks. The whole exercise has pissed me off, big time. Herbie.

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.

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.

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.