240 TDO4H-13C base wastegate pressure

pigdogdave @pigdog Wollongong NSW

Hey guys so i just recently converted my 240 to turbo and i need a little help understanding something cause this turbo jazz is all new to me .

firstly here's a brief rundown of my setup .

B230fk motor from 940T, A cam, 90+ manifold and 13c turbo from late model 740T (i think its a 13c theres no tag it looks like a 13c though ) XC70 injectors, 3" downpipe, hi flow cat and full 3"system , Ecu from 94 940T .

So the plan was to run a manual boost controller and keep it around 10-12psi.

at the moment theres no boost controller im just running wastegate pressure and im getting 15psi .

i thought the base pressure on these were 7-8psi?

i haven't had a look yet if the rod is adjustable and could've possibly been adjusted by the previous owner .

i also thought you hit fuel cut at 15psi but im not ..

now everything seems fine at 15psi, it pulls hard and there's no pinging or any suspect noises etc but to be on the safe side i would still like to keep it around 12psi , its the daily and my misses drives it more then me she doesn't need that much boost haha


any help would be great, ive never owned a turbo or played with turbos so its all new to me and im kinda just figuring it out as i go..


cheers guys


ALVO360
«1

Comments

  • it's 7psi

    That said, even with a stock WG, with an open DP I've had previous 7/94x cars that would hit 15psi because the WG could not open far enough fast enough to keep up. With a 3" DP and everything else you have this is totally plausible

    LH2.2 has a boost cut, LH2.4 generally does not

  • pigdogdave @pigdog Wollongong NSW

    Ah ok that makes sense .

    in your opinion is 15psi too much to run safely , the car doesn't get driven hard often but i will give it a boot full here and there

  • Fuel cut, not boost cut.

    Take the hose off the wastegate (off tap), and go for a drive. LH 2.4 cuts fuel beyond 12psi

    The fuel system cannot keep up with that much air

  • pigdogdave @pigdog Wollongong NSW

    Ive know a few people running 12-14psi on lh2.4 , and I'm hitting 15 and not getting fuel cut , my AFRs are good too

  • carnut222Greg S @carnut222 Daylesford VIC

    Regarding over boost, there has to be a switch connected to a vacuum hose to the inlet manifold, and that switch has to do something. On the earlier cars, IIRC it just cut the fuel pumps. Not sure about LH2.4, but if there’s no overboost switch the fuel injection computer has no way of knowing if you’re in an overboost situation so it can’t do anything at all. Look for something that looks like this...if it is same as 740T and 240T (USA version). It was under the dash near the pedals on the 240 IIRC. Vac hose goes to vac port, and wires coming out of switch. It just opens (or closes?) the circuit at a pre-set boost value...


  • pigdogdave @pigdog Wollongong NSW

    Ah ok that makes sense I was thinking how would it even know what boost I'm running haha

    I don't have that bit under my dash it's a standard 240 with all the turbo goodness thrown in and I never took that bit from the donor car

  • LH2.4 has no boost cut. I know this because the two times Ive had my wastegate hose disconnect its maxed a 20psi gauge with no boost cut. It also isnt 12psi as I have mine set to 15 much like other people. LH2.2 had boost cut which was that small switch under the dash that connected to the EZK. A popular mod was to remove it and boost away. LH2.4 for some unlucky people will hit the end of the map if you flow more than the MAF can read and this has more to do with turbo sizes larger than the stock Volvo ones as they flow more volume in addition to pressure causing the MAF to go out of bounds causing fuel cut. This is where the 012 MAF mod originated from.


    In regards to your original question Dave. The reason why you are seeing 15 psi is because of your 3 inch exhaust. It flows much more than the 2 1/4 system the 13c is supposed to be used with and being such a small turbo it will more than happily spin faster with the reduced back pressure. The same happens with any of the small Volvo turbos up until around the 18t where its larger size helps control the overboost. Another part of the issue is the ignition curve of LH2.4 doesnt compensate for the larger exhaust and as long as it doesnt see knock it will keep advancing it to make more power and in turn spool the turbo higher. It was never designed to be used with a large exhaust. Mike is right in that the base pressure should be 7psi. The 13c and 15g have very weak wastegate actuators and it will struggle to regulate the boost properly. The solution is to replace it entirely with a Garrett unit or an aftermarket unit such as Mamba or Forge. I have a Mamba unit installed on my B23ET with a 16t running LH2.4 with a 3inch exhaust from downpipe to tail and with the 15psi spring it will hold 13psi rock solid no matter how hard I push it. With the stock actuator it would take a while to come onto boost and then overboost to 15psi just like yours does even though it should only be 7 because it was struggling to keep the door shut and then it would blow open but not blow open far enough.

    carnut222Dauntless
  • carnut222Greg S @carnut222 Daylesford VIC

    Thanks for clearing that up @Slowbrick It is interesting they didn’t really put any safety mechanism in the LH2.4 cars.

  • edited May 17

    The MAF is the safety mechanism for LH2.4. As long as the reading on the MAF matches a setting in the fuel table then it can provide the fuel needed. Once that goes out of bounds then it can no longer provide the fuel so it cuts it until the reading comes back in bounds. Its part of the reason why LH2.4 can be used to run E85 with the only modification being installing a larger fuel pump and injectors to cater for the decrease in fuel density. LH2.4 is a vastly superior ECU to 2.2 and having owned and lived with both in turbo applications ive come accustom to their oddities hahaha.

    Also in my previous comment I mentioned replacing the wastegate actuator. I made an error in that recommendation as I was basing that on experience with a TD04HL family turbo and not the TDO4H. Im fairly certain they both have the same size internal flapper but if the flapper is smaller than a TD04HL then the root cause of the problem will be that the flapper hole is too small to accommodate the increased flow and a stronger actuator may not help and the solution will be to introduce back pressure in the exhaust via a baffled muffler or a higher cell cat. If youre feeling keen or can get hold of another exhaust housing then porting the wastegate hole could be a very successful solution as it is going to be the root cause of the problem but if you go too far then you risk taking away too much material and damaging the housing.

    ALVO360
  • pigdogdave @pigdog Wollongong NSW

    Thankyou @Slowbrick that explains alot Ive never played with turbos nor owned one so this is all new to me .

    When I was getting information for the swap everyone said go 3" dump and full system so that's what I did haha

    Not sure what my best plan of attack is now , just leave it as is and run 15psi or start looking into my other options , the car feels great and drives great , it doesn't seem unhappy with 15psi and it doesn't get driven hard often but I would like to avoid breaking things and would like to focus on all my suspension and brakes etc etc before diving back under the bonnet to change stuff.

  • edited May 17

    I would definitely be servicing the entire worn out suspension, brakes, rubber bushings the lot


    Don't forget the cooling system

  • pigdogdave @pigdog Wollongong NSW

    That's already in the works , I just ordered everything from DVS Bilstein B6 shocks front and rear , new springs , all bushes , strut brace ,chassis braces , swaybar links , adjustable Panhard etc etc

    Cooling system is fine , new radiator, water pump , thermostat , D088 coolant hoses etc

    I will be looking to upgrade the intercooler to an alloy unit and going efan , trans cooler setup is in , probably add an engine oil cooler too


    Everything was done to the motor while on the stand , new seals and gaskets all round ,headgasket , timing belt etc etc

    Every hose etc is new , completely redid the pcv system


    It was originally a low ks squirter block from a 95 940T it runs bloody smooth and quite

  • edited May 17

    I was getting fuel cut @ around 14-15psi before I swapped my LH2.4 ecu with a chipped unit.

    I think @Slowbrick is on the money with this. Apparently the MAF (AMM) sends out a voltage to the ecu to determine Air Mass. This range is said to be between 0-5V.

    Some people put a 4.7v resistor diode between the signal wires on the AMM which limits the voltage being sent to the ecu and in-turn eliminates fuel cut when the signal meets or exceeds 5v.

    Do you know if your ecu is chippable, Dave? You can cross reference part numbers or lift up the tabs on the ecu and pull the cover off to take a look.

    I also don't see how having a 3" exhaust would increase your base boost pressure 8psi beyond the factory boost setting.

    A worn or stuck diaphragm in the actuator could be the problem. Swapping out to a known working actuator or buying an upgraded version off the shelf is what I'd do. I bet if you disconnected the actuator and tied the wastegate arm to the open position you wouldn't be building much boost, if any at all.

    Additionally, the boost pressure your turbo and actuator see vs the boost pressure your intake manifold sees are going to be different readings. Boost pressure from the turbo will always be higher and this one of the reasons why a 15psi actuator spring won't read as 15psi on the boost gauge.

  • pigdogdave @pigdog Wollongong NSW

    i was reading about the diode mod just before actually , if its all controlled by the maf on lh2.4 i dare say i would be close to hitting fuel cut but im not which is weird , it hits 15psi everytime on WOT and seems to just do its thing haha

    i havent checked if my ecu is chippable ill have a look at its number tomorrow and see if it is .

    as fun as 15psi is i would like to bring that down to around 12 i dont like the odds of not breaking something at 15 .

    to be perfectly honest im rather confused and my brain is melting trying to take in ALLLL the information ,im not sure what the best approach is/what the hell i should be doing, i dont really want to modify my exhaust again considering it just got done and cost a decent chunk of change , all i do know for sure is i need a wee bit less boost haha

    At this point i need someone to speak to me like im a mentally challenged toddler and just tell me where to throw my money haha my mechanical knowledge / skill is really not up to most the things i do, how ive gotten this far is beyond me , im good with nuts and bolts, i undo and do up stuff real good, understanding the things im undoing and doing up is a whole other story

    these spiny turbo things are fun but they hurt my head and my wallet.

  • I'd just get a new actuator and go from there. You can either put in a 15psi springs and run it like that or put in a lighter spring and run your MBC to the desired boost pressure.

    I doubt you'll be hurting anything by running 15psi on the daily - Especially if your AFRs are good.

    If you get another wastegate and it allows you to bring your base boost down, then just use your MBC and play around with a nice combination between power and piece of mind.

    Your pistons, crank, rods, head and gasket will comfortably take 15psi all day if your AFRs are on point. The power sweet spot for mine was between 11.5:1 and 12:1 @ WOT.

    13:1 is too lean

    Anything less than 11:1 is too rich.

    14.7:1 at idle - or as close to it.

    I have a spare actuator if you want it for testing? I could send it out to you on Monday if you're keen to investigate further. My money is on the actuator(1), or possibly a restriction in the ports coming from the turbo going to the actuator(2), or even a partially seized wastegate arm not opening all the way(3).

  • carnut222Greg S @carnut222 Daylesford VIC

    I recommend testing the actuator...pull the hose off it and use a hand vacuum/pressure pump such as a Mighty-vac unit and see what pressure is when the actuator arm starts moving, and see if it moves the full stroke as pressure is applied. If you don’t have a hand pump, come up with a way to use your air compressor on a very low setting to see if the actuator moves. I too am surprised that the boost is building so much if the actuator is functioning properly and is adjusted correctly. My dad put a full 3-inch system on his 240 turbo LH2.4 conversion and he had no boost problems. I think he said he hits a max of around 12 PSI when the Turbo+ kit kicks in...

    pigdog
  • pigdogdave @pigdog Wollongong NSW

    my AFRs seem good but i do need to keep watching it while im driving to be sure everything is on point , i havent been driving much lately and trying to glue my eyes to the gauge while boosting and shit has proven to be more difficult then it should be haha i might just set up a camera and go out for a drive so i can go back and watch what its doing and send it to you for a second opinion hahaha

    the one i know for sure is its 14.6/7on idle

    seems to be around 15 cruising

    and from what ive seen around 12 WOT but ill need some more testing to confirm that .


    i might try what @carnut222 just recommended and see what its doing before i try a diffrent one, i havent got a hand pump or anything that i could use, my compressor has 1 setting ...allll the air!!!

    i might speak to my mechanic mate and see what he has at his shop to help me figure it out and then maybe look at changing the actuator (no idea how to do that but im sure ill figure it out) if its nuts and bolts that is what i do best after all.

  • Is your dad using a Manual Boost controller or an adjustable Actuator to achieve 12psi?

  • carnut222Greg S @carnut222 Daylesford VIC

    He’s just using the stock 780 Turbo turbo, actuator, and also the Turbo+ kit that activates a bleed valve on the actuator dashpot to achieve higher boost over 3750 RPM IIRC at full throttle only. However, thinking about it he might have a Garrett turbo and not a Mitsubishi...so that could be a difference.

    ALVO360
  • edited May 18

    Ok, seems like there is a little bit of confusion going on here. Lets try and clear some of it up :)

    I also don't see how having a 3" exhaust would increase your base boost pressure 8psi beyond the factory boost setting.A worn or stuck diaphragm in the actuator could be the problem. Swapping out to a known working actuator or buying an upgraded version off the shelf is what I'd do. I bet if you disconnected the actuator and tied the wastegate arm to the open position you wouldn't be building much boost, if any at all.

    The reason for this is flow. The internal wastegate port has been designed to control boost at a predetermined flow window. So real quick lets go over this. When your wastegate is connected it keeps the wastegate port shut to use the exhaust gases to build heat and momentum in the turbine to spin the compressor to build boost. When the compressor builds the required boost level (7psi or whatever) then the wastegate diaphragm will see the vacuum signal and open the wastegate port. This bleeds of exhaust from the turbine housing and directs exhaust into the downpipe and those gases encounter the gases travelling from the engine and are met with turbulence and backpressure. This combines with the backpressure the turbine is already experiencing in the exhaust housing/downpipe. The combination of the wastegate port bleeding gases from the turbine housing and the backpressure on the turbine wheel keeps it at a set speed which then maintains the desired boost level.

    Ok, so when you increase the exhaust size much further than the stock level, especially the downpipe then you effectively remove that backpressure from the turbine and can increase the backpressure on the wastegate port as the gases are now flowing into the massive flow increase from the turbine. So now instead of a nice transition you end up with spiking and boost creep the latter is what Dave is experiencing. This is caused by the stock wastegate diaphragm not being able to overcome the backpressure on the port quick enough caused by the increased flow in the downpipe. You also have the issue of the turbine spooling much sooner than it normally would. This can cause the actuator to stay shut a little longer and then blow the door open at the last second but by then the turbine is already spinning faster than it should be and now instead of making 7psi youre making 15. This issue compounds in that now the door is open at a later and higher boost level than it was designed for and the gases physically cannot get out of the housing fast enough to bring the turbine speed down to the level needed for 7psi so it stays at 15.

    Ok second point If you were to force the gate open then yes it would make no boost. This is because turbos work from momentum and heat. Forcing the gate open before boost is made would bleed off the heat and momentum needed to get the turbine to start spooling, this would present itself as a big obstruction in the engine and the wheel will effectively just freewheel in the housing and not build any boost. The problem with small turbos and big exhausts is managing the momentum already there and keeping it at a set level. If you try to manage the momentum before its there then it wont be a reliable test and wont tell you anything and the engine wont make any power as it will be seeing a big exhaust restriction and not increase in intake flow. I had this happen to me when the wastegate pin broke on my 16t and I had less power than I did when I had a sick B21. The engine wouldnt even rev out to redline and used a tonne of fuel. Its like sticking a potato in your exhaust hahaha.


    i was reading about the diode mod just before actually , if its all controlled by the maf on lh2.4 i dare say i would be close to hitting fuel cut but im not which is weird , it hits 15psi everytime on WOT and seems to just do its thing haha

    The reason why youre not hitting fuel cut is because the MAF isnt reading pressure its reading airflow. A 13c is a very small turbo that doesnt flow very much once it gets above 12psi. If you were reaching 15psi with a larger turbo like a T3/T4 or even a 15g then you would be hitting the airflow governed fuel cut as your flow would be outside the acceptable window for LH2.4. Look up turbo CFM to see what I am talking about. 15psi from one turbo is not the same as 15psi from another if both turbos are different sizes. LH will be seeing the air being drawn in by your turbo and it doesnt care if its at 40psi or 7 psi as long as the volume of the air does not exceed the governed limit for which it can supply fuel for. At 15psi with a small turbo like a 13c your biggest concern is heat as the 13c become severely inefficient at pressures higher than 12psi and the boost being made turns to superheated air. You should resolve this before summer as you will have heatsoak and potential detonation caused by increased intake temperatures.


    i dont really want to modify my exhaust again considering it just got done and cost a decent chunk of change , all i do know for sure is i need a wee bit less boost haha

    Your exhaust is fine. Both of my redblock turbos had 3 inch exhausts. The problem is going to be the small 13c is a very small turbo and as such doesnt take much momentum to get it spooling and the large exhaust gets it spooled and keeps it spooled very quickly. The wastegate simply isnt flowing enough to control that momentum.


    I'd just get a new actuator and go from there. You can either put in a 15psi springs and run it like that or put in a lighter spring and run your MBC to the desired boost pressure.

    I doubt you'll be hurting anything by running 15psi on the daily - Especially if your AFRs are good.

    If you get another wastegate and it allows you to bring your base boost down, then just use your MBC and play around with a nice combination between power and piece of mind.

    I agree that he should get another actuator, but not for the reasons of hoping to resolve the boost creep. I would be getting a new actuator for the increase in boost response and for a more stable boost curve. I highly doubt a new gate actuator is going to resolve the flow issue of the small 13c port in a large exhaust. I would be looking into porting the gate port and go from there. Do some research on turbobricks as this subject has come up plenty of times from people installing large exhausts on 13c equipped cars.

    He’s just using the stock 780 Turbo turbo, actuator, and also the Turbo+ kit that activates a bleed valve on the actuator dashpot to achieve higher boost over 3750 RPM IIRC at full throttle only. However, thinking about it he might have a Garrett turbo and not a Mitsubishi...so that could be a difference.

    The 780 turbo came with a Garrett turbo which has a much larger wastegate port. In addition to the larger port the turbo is larger and slower to spool. Therefore its mass helps control its momentum when installed in a large exhaust. A 13c is an incredibly small turbo designed for quick spool in a standard exhaust. The two are not comparable.


    Sorry for the massive wall of text and I'm not trying to correct everyone. You all are on the the right track and have great suggestions but I just thought id steer us into the more "correct" direction with a little bit of theory added so you guys can all hopefully learn something new. Ive had this exact same issue with a 12b on a B230FX with a 3 inch exhaust. It would spike and overboost if I punched it and had to always roll onto the throttle to keep it remotely controlled. Swapping to a 15g with a ported gate and conical housing resolved the issue as the conical housing introduced backpressure on the turbine and the ported gate helped flow out the gases. Its all good fun at the end of the day and props to you Dave for getting the car up and running. Dont keep discounting your skills and knowledge, you will find you know alot more than you think and at the end of the day you are out there with your tools and time getting your hands dirty and thats what counts.

    ALVO360242GTDauntless
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