I’ve spent countless hours playing with Matchbot. There list of turbochargers doesn’t include one small enough. So, I overlayed transparent graphs I found on various Matchbot screenshots, stretching to cause units to correspond. I have the Turbine Sizing Selector set to the bottom curve. At that setting a 28mm waste gate is indicated.

If I have the BOV set to 6 psi, won’t that alleviate over-pressurization in the event the electronics don’t work quickly enough?

Just asking.

 

Ummm...I knew what I was wanting to do was upside down to what anybody else wants but there’s no forum for upside down. So, here I am.

 

That's not what I was getting at.

You are clearly very well educated and have a well thought out plan of what you want to do. The only reason you are getting kickback on your plan is that most feel you are over complicating what should be a fairly simple plan. Your plan should work fine, just lots of moving parts. Most here like simple and time tested.

 

It’s really interesting to me that my plan is seen as MORE complicated. I see it as less. I intend to leave the engine, all its sensors, and the ECM as-is. The turbocharger that would be used will provide only enough boost (“boost” being above 14.7 psia) to keep the thing from spinning out of control (thanks, Mnix). That’ll be true only up to an altitude of 4000 ft which would be about Boise, OK, as I’m headed to high country. Beyond there, maintaining 14.7 psia will take more than 2 psig.

I would depend on a one-off waste gate control. If that seems complex, Google “Arduino”, “stepping motor”, and “pressure sensor”. You’ll find everything you need to know to build what I outline. This would be the first money I would spend and I would fiddle with it on the bench quite a while before going ahead. Response time is a concern aswell as hysteresis. If that doesn’t work I’m back to a knob, a psig gauge, and a psia gauge.

This all seems simple to me BUT what about intake temperature, back pressure, turbulance? They’re a factor but how big where the highest pressure is 16.7 psia?

 

The answer is: it depends.
It could very well be that your ECM is capable of handling it all, it could also be the first time you run it you ping the motor to death because some sensor isn't reading as the programmers intended, or anywhere in between. You will have to test it to know.

 

Also, you should use the biggest gate you can fit. You want to make sure that you can completely bypass the turbo.

 

All that might be simple...if you have the parts and computer and so on to run it. A basic wastegate with a light spring to keep the boost to 2-3 psi will be as simple as it can get.

 

Leave it to an engineer who has never done something to tell the people who have countless hours and experience actually doing it, what is simple and what isn't.
LOL.
I'm almost ready to start thinking its April, or some guy is going to port his engine while running with a bag of sand blasting media. Where is the Punk'd guy?

I'm not trying to be a dick, and i truly hope whatever project you take on works brilliantly, but you have to realize the sort of absurdity with this whole idea/thread right?
I mean the people you are talking to, and asking for advice from, have built everything from successful single digit turbo cars, (shit one guy on this thread has done it on a fucking snow machine!!!! 3 different times!!!) to hundred thousand mile turbocharged daily drivers that are making multiple times factory output all in their garages, with often times, minimal tools. Most importantly they have made all the mistakes necessary to accomplish "better" then your goals for less money, in less time, and yes, more simply.

 

Reviewing the estimated intake air temperature rise tells me there will be a problem with knock with a compression ratio of 10:1. That alone adds enough complexity to eliminate any interest I have. Thanks for your time.

 

So the air temp is what got you? Not the open source generic arduino waste gate at 40 time a second? Not the rube goldberg BOV? Not the wierd "lets trick the ecu into sea level" thing?
It was the ten to one thing?

I feel like three pages ago............................ Ah fuck it.





Whatever you decide to do, I hope it works out, I really do. Good luck.

You can lead the engineers to water, where they will stand around designing a straw till they die of thirst.

 

Thanks but I've decided it's going to be more trouble (and money) than it's worth. You and others were right about complications surrounding turbocharging affecting even my little nothing setup but you're incorrect with respect to my original ideas. They would work. After all, who do you suppose it was that came up with all that nifty go-fast hardware you bolt-on to your screamer? It was guys like me and guys like you called it a "Rube Goldberg".

 

What about water/ meth injection ?

 

It is true. Alfred Büchi was indeed an engineer.

 

If you read back through, nobody said it wouldn't work. We said it was overly complicated for the very modest results you were after, and there were way easier, cheaper, and much more proven ways to go about it. But I don't think anyone actually questioned if it would work. Stepper motor gate control has been used in the passed, all the way back into the eighties and is currently being used to control boost in almost all of the modern VNT turbo systems around (albeit with rack control as apposed to a strait wastegate control, but it does control boost)
Again my criticism was based on an over complication of what was needed to meet your goals.

So was Rube goldberg

 

I have never heard that name so I had to google it.

From Wikipedia:
Goldberg is best known for his popular cartoons depicting complicated gadgets performing simple tasks in indirect, convoluted ways. The cartoons led to the expression "Rube Goldberg machines" to describe similar gadgets and processes.


Now the reference makes sense.

 

Everyone has seen his "designs" but alot of people do not know the name behind them. he was actually a super interesting and cool guy. Who also happened to be very well educated.
Its worth the twenty minute rabbit hole to read about the dude.

 

Inasmuch as there is still constructive input I would like to say thanks and offer my definition of “complex”. It was my goal to avoid doing modifications of any kind to the engine other that changing the exhaust manifold and adding a turbocharger with a boost control that maintained factory rated power at all altitudes. Anything more than that I deem as “complex”.

Water/methanol might bring down temperatures to something that the stock ECU would tolerate but under worse case conditions the injection would be turned on continuously for hours probably requiring more liquid than is reasonable to haul. That would bring up the subject of intercoolers. There’s no room for a big cooler. None.

I don’t see the construction of a special boost control as “complex”. To me that seems simple though I would expect quite a bit of bench time using a vacuum chambers and maybe an oscilloscope. It would operate as a variable tension spring, with the tension getting ever tighter as I go up in altitude, always limiting boost in a way that prevents more than factory rated power. That’s so there’s no abnormal stress placed on the drivetrain beyond factory ratings. I don’t want to break anything, i.e. “reliability”.

As for turbulence, do flow straighteners not resolve that problem?

You’ve talked me out of it but if it amuses the group, talk me into it but please keep in mind my goal.

 

I am not convinced on the idea of turbulence. Forced induction is not moving the air necessarily faster through the engine, but just denser air.

 

You don’t need a big intercooler for 175 hp look at the intercooler on the wrx it makes more power and it is pretty small.
Really how big is this rv that you can’t carry a few extra bottles of washer fluid or boost juice etc. you should have room for a large reservoir or use the washer reservoir. I wouldn’t waste my time making a wacky boost controller just put a 3 lb spring and use a manual boost controller you can adjust with a turn of a knob from your drivers seat.a few pounds of boost won’t put excess strain on the drivetrain. Your way over thinking it

 

Interesting thread.
I understand what is trying to be achieved but I would think that one of the most important aspects of this is going to be ecm control. To me this sounds just like another old school idea into tricking the ecm, you should look into whatever guys do with the factory set ups in other models. You can always run a water to water cooler if space is limited. You need away to add boost as elevation increases, a map sensor should do that no?
Don’t give up and keep the discussion going, some good ideas might come up.