2015 LTX with turbo, blown head gasket??

[MIDWAY]

Any blown head gaskets?? I have 15 LTX with Push turbo, 7 lbs boost pump gas. Was up in Canada and started to overheat pushing coolant out the over flow, head gasket?? 2000 miles now

 

[stingray719]

7 pounds boost with stock fuel pump?

 

[Yamadog]

Last season both Ymahatim and myself blew motors with the MPI Stage 1 kits not the trail kits at 6#'s of boost mine went at 800 miles and his went at 1500. What were your AFR #'s like? with a stock fuel pump 7#'s is running lean at WOT.

 

[DC5]

Stock fuel pump is good for more than 7lbs but injectors are not. Not sure what push does for extra fuel but either way anywhere near sea level 7lbs of boost is too much for pump fuel. If you are lucky it is just the headgasket. When you take it apart make sure the the block is still flat. The area between the cylinders tends to sag when the headgasket goes.

 

[Yamadog]

And yes that is a first sign of a head gasket coolant out of the overflow. 7#'s on the stock motor and fuel system is really pushing it. anything over 6 should have head shim and upgraded fuel pump. And then over 8 the 4th injector is needed cause the small injectors cannot provide enough fuel.

 

[Studroes144]

Stock fuel pump is good for more than 7lbs but injectors are not. Not sure what push does for extra fuel but either way anywhere near sea level 7lbs of boost is too much for pump fuel. If you are lucky it is just the headgasket. When you take it apart make sure the the block is still flat. The area between the cylinders tends to sag when the headgasket goes.

I've heard just the opposite, I actually have spoken with guys who do an upgraded fuel pump and regulator and run anywhere from 8-10 pounds with stock injectors, using race fuel of course. I'm getting the upgraded fuel pump kit put on my stage 1 mpi right now and should know for sure in a week or so. With my gems controller maxed out I can only run 5 pounds, anything more and it'll run lean. I have head studs and thicker head gasket so in shooting for 7-8 pounds and hoping stock injectors keep up with the new fuel pump.

 

[cannondale27]

Studroes the injector is supposed to be the variable since it can be most accurately controlled. All it needs is Volume and constant pressure. If fuel pump and regulator arent providing that on a Turbo motor then they also arent on a stock motor.

http://www.rceng.com/technical.aspx

 

[DC5]

I've heard just the opposite, I actually have spoken with guys who do an upgraded fuel pump and regulator and run anywhere from 8-10 pounds with stock injectors, using race fuel of course. I'm getting the upgraded fuel pump kit put on my stage 1 mpi right now and should know for sure in a week or so. With my gems controller maxed out I can only run 5 pounds, anything more and it'll run lean. I have head studs and thicker head gasket so in shooting for 7-8 pounds and hoping stock injectors keep up with the new fuel pump.

You can do that because with the pump and regulator you are raising the fuel pressure with boost. At stock fuel pressure the injectors are all out at 6lbs and with upgraded injectors the stock pump is out at 10lbs.

 

[stingray719]

As I have not tested myself I will take MPI word for it as they have never steered me wrong. http://viper-mountainperformance-co...ll-MPI-Viper-Kits-most-other-brands_p_14.html

Viper Stage Fuel Pump & Regulator Upgrade (Includes):

• High Volume OEM Walbro Fuel Pump
• Returning Style 1:1 Boost Sensitive Regulator
• All required Plumbing & Hardware
• New pump & regulator typically required above these boost levels:
  • 0-2000ft: 6psi
  • 2000-6000ft: 7.5psi
  • 6000-10000ft: 9psi

 

[Studroes144]

You can do that because with the pump and regulator you are raising the fuel pressure with boost. At stock fuel pressure the injectors are all out at 6lbs and with upgraded injectors the stock pump is out at 10lbs.

So for the mpi kit the fuel pump is the way to go with the use of the gems controller. If you have another kit or a kit running a pc5 where the tuning capabilities are much greater then going with bigger injectors is the way to go. Bigger injectors on an mpi kit using the gems controller would be way too rich on low end and probably run lean on long wot runs, all depends on tuning capabilities. Sorry no relevance to the OP, but good info none the less.

 

[DC5]

So for the mpi kit the fuel pump is the way to go with the use of the gems controller. If you have another kit or a kit running a pc5 where the tuning capabilities are much greater then going with bigger injectors is the way to go. Bigger injectors on an mpi kit using the gems controller would be way too rich on low end and probably run lean on long wot runs, all depends on tuning capabilities. Sorry no relevance to the OP, but good info none the less.

Yup, sounds about right

 

[cannondale27]

Really the problem is how the fuel is controlled Studroes. Not very accurate using pressure. Old Tech. Push uses a baro/boost based map using stock injectors and pump at 8lbs boost. Midways headgasket just must not have been able to take it.

 

[Srxspec]

Really the problem is how the fuel is controlled Studroes. Not very accurate using pressure. Old Tech. Push uses a baro/boost based map using stock injectors and pump at 8lbs boost. Midways headgasket just must not have been able to take it.

MPI has a boost based map as well. That's the MAP sensor you install into the plenum on the 180 Yammy kits or on the 190 kits as well (used to be a little blue hose). MPI is going to the larger fuel pump with rising rate regulator to get more fuel through the stock injectors. Stock at 5.8 lbs of boost the fuel pressure actually drops off approximately 1 lbs at higher RPM. Want all the fuel you can handle? Install 550 or so injectors and the larger fuel pump or regulator and have unlimited fuel, but you'll need a PCV or something similar to remove fuel where not needed.

Either way, anything over 6 or 6.5 psi of boost on pump gas is playing russian roulette with a stock compression motor.

 

[cannondale27]

All I know is no OEM Auto or Bike controls AFR using fuel pressure for at least 10 years now. Surprised Yamaha approved that system.

 

[TD Max]

All I know is no OEM Auto or Bike controls AFR using fuel pressure for at least 10 years now. Surprised Yamaha approved that system.

They have to do something when you add a turbo. Especially when you are locked out of the factory ECU.

Time-pressure-orifice regulates the amount of fuel delivered. When time is not enough you add pressure or orifice. Pressure is the simplest.

Think about it this way: NA engines have Atmospheric pressure (14 psi for round numbers) or less (vacuum) in the intake tract. Add 6 psi boost and you are fighting that with the spray PLUS you need to deliver more fuel through the injectors to match the air.

Ideally we'd have a MAF sensor and wide band O2, but then again how would that work in the environment of a sled? Snow, ice, fog, cold temps, etc