Ever heard of putting fuel ejectors before a supercharger/turbo?

It's called a draw through turbo. They used to be somewhat common with carbs because some carburetors don't handle positive pressure well. The downside is that the fuel tends to corrode the turbine wheel. With the introduction of fuel injection, the benefits no longer exist but the drawbacks remain.

Only the hot side does. The temperature delta between the compressor and the turbine is huge.

No. I think you're thinking of NAWS

Because your turbo/supercharger will detonate

Lubricating the rotors, in the case of roots blowers.

Why would you deliberately do this? The whole principle of direct injection is that you get the fuel mixture as close to ideal as possible by injecting almost immediately before combustion. Injecting before the turbo would severely complicate things for no good reason. You now have to worry about fuel inside the turbo and intercooler and how it will interact when going from part throttle to full throttle. The only reason why direct and port injection are combined is because otherwise the oil injected into the intake from the PCV system causes massive carbon deposits that need gasoline to wash away.

Fuel is not a lubricant in a 4 cycle gasoline engine.

yup
it makes fuel distribution an issue

>The only reason why direct and port injection are combined is because otherwise the oil injected into the intake from the PCV system causes massive carbon deposits that need gasoline to wash away.
No, that's not why stratified charge injection exists. Intake valves fouling is literally not a concern for automotive engineers, because it doesn't become an issue until after the expected lifespan of the car.

Isn't that how moog had to do it on the mini?

And yes, it's a thing. See There's just no point if you have any choice in the matter as injecting into the cylinders or at least each intake port is much, much better.

Might as well ask this because it seems appropriate.
I just installed a supercharger last night and while I was cleaning and replacing the fuel injectors. I took a small piece of shop cloth and wiped away the dirt surrounding the ports and of course on the last port I was cleaning the small paper towel (about thumbprint size) fell off my finger and down into the port.
I haven't started the vehicle yet but that had weighed on my conscious, will it be okay or should I be worried and attempt to break down my engine to fish it out?

You're fine.

I'm saying that the only reason why OEMs are using both port + direct injection is because intake valve fouling can sometimes be an issue within the warranty period depending upon the design.

Theoretically you only need direct injection. There are a lot of engines that don't have port injection at all.

>paper towel
>into somewhere that is soon to be at several thousand degrees and psi
It won't hurt shit, m8

Well since I got an honest quick answer, I'll share another problem.
I have a sheared screw on an OEM part that was repositioned during the install so that it sits closer to engine on the side as opposed to the intake manifold.
I'm wondering if there is an adhesive that I can use to keep it steady while attached to the engine temporarily.

>I'm saying that the only reason why OEMs are using both port + direct injection is because intake valve fouling can sometimes be an issue

It's for fuel efficiency, power, or both.

I figured but again, this kit cost about $7k and I'd be very upset if it were ruined by a paper towel. Understand my paranoia.

Thats kind of a vague description, but I like that jb quicksteel stick stuff. it's easy to deal with and can handle underhood temps

This guy...

To be specific it's the plastic VSV that I need to stick somewhere.

Thought I attached this pic

zip ties maybe?

No, the point is to create a locally rich mixture that can be reliably ignited around the spark plug, while the rest of the intake charge is very lean. This allows the engine to use less fuel without causing lean misfires, which means you can have much higher cruising efficiency in a car with high peak power capacity.

Intake valve fouling IS NOT a concern whatsoever.

Could work, it's cocooned in electrical tape right now.

I'd take it out. You're probably fine, but it doesn't take a whole lot to upset a compressor that's spinning at over 100,000 RPM.

Last question that I have to have some closure on before I exit the thread.

There are 8 bolts attaching the supercharger to the block.
Right now with my basic tools I can for sure torque down 4.
The other 4 I can tighten but not torque down or even reach at all without using a very specific socket that nobody in my area has.

Is it safe to drive AS IS, to a garage just a half mile down the road so I can get them to torque these down or should I not start it at all until Incan torque them all down?

The main issue is that sometimes you want a homogeneous charge. Especially if you're dumping blowby back into the intake. Port injection does this so your PM emissions are dramatically reduced and you don't need a particulate filter.

You're probably better off running with only 4 torqued, taking the other out so they can't rattle loose

If they're all reasonably snug then you should be ok do drive a half mile.

just don't go for max boost yet

Really? It absolutely is a problem depending upon what engine you're looking at. VAG has a few engines that are notorious for intake valve fouling.

And there are still benefits to port injection, if there weren't we wouldn't be seeing engines like the VR30DDTT.

3M double sided tape, its held the fuse box in my car for 60k miles.

Thought about doing this when i had a L67.
My thinking was that spinning the charger harder=hotter charged air in the intake manifold.
Having an injector/'s upstream would help lower intake temps so you could runner higher boost.
Never got around to doing it as I moved on from that lump of iron.

>VAG has a few engines that are notorious for intake valve fouling.
Yeah, after 80,000+ miles, which is as long as they're designed to last.
>And there are still benefits to port injection, if there weren't we wouldn't be seeing engines like the VR30DDTT.
So port injection is good and that's why Nissan is making a direct injected engine? I don't get it.

Putting your fuel delivery before the compressor was common when we still had carburetors. That way, you didn't have to tune the carb for a boost signal, since it always had an atmospheric signal (just more 'vacuum').

This also had the advantage of lubricating the old Roots blowers, since they use rotor seals. This improved compression efficiency, resulting in comparatively lower intake air temperatures. Since the fuel could vaporise during the air compression, it also kept the air temperature from going up as far.

Same theory works for all other low-RPM compressors(like twinscrews). Inject before them, and you'll get lower IAT's then you would by port injecting. Lower IAT's = more power potential.

Now, you could still do this using injectors instead of carbs. However, you'd lose the excellent individual port delivery of the injector. What you'd want, is delivering 20-25% of fuel before the supercharger to lubricate it, and then delivering the meat of the fuel in the ports. Best of both worlds. Alternatively, you could deliver all of your fuel via port injection, and then add water-methanol before the supercharger. This stuff seals good enough, but will massively drop IAT's, since it evaporates better than regular fuels.

Now, turbo's (this applies to centrifugal superchargers too). You can't really inject regular fuel before them. Saab researched this. Since you're not inject gases, but rather, you're injection tiny tiny droplets of fuel, those droplets hit the turbine blades, and damage them eventually. Fine for a 10000 mile a year dragster, not good for your daily driver. Also, since you probably have an intercooler (which you should), the fuel droplets will be pulled out of suspension, and they'll puddle in the intercooler. You can imagine what a backfire will do to that...

So, you'll want to inject behind the intercooler. I'd inject the water-mrth (if applicable) near the throttle body for maximum evaporation (and heat reduction), and then port injection for accurate fuel delivery.

There is one exception: you can inject gaseous fuel before the turbine. An example would be propane (LPG) Since it's fully gaseous, it will be harmless against the compressor blades. Backfires can still be an issue, but it'll massively cool the entire intake tract.

Oh, and anywhere I said port injection, you can also use direct injection, if possible. It can make even more power in combination with boost.

VAG's 2.0T engines have needed carbon removal as early as 60k miles depending upon how much time is spent at low RPM.

I misspoke, the VR30DDTT may be direct injection only but a number of OEMs are using dual injection schemes to improve fuel economy, emissions, and reliability: wardsauto.com/news-analysis/toyotas-twofold-strategy

It is in a Roots blower - it improves rotos seal, which causes more efficient compression (so less IAT heat rise). Also, evaporating it during the Roots' compression causes lower IAT's.

>what about mixing air and fuel before the air is compressed
First off, you increase the chance of detonation in your intake tract, which is bad, mkay.

Secondly, you're going to get lower IAT's and a better evaporisation. Because of the fuel droplets inside the supercharger, it will both seal better (=more efficient compression=lower IAT), and it will also evaporate the fuel droplets (=better evaporisation). This evaporation also draws heat from the intake air (=lower IAT).

>Because your turbo/supercharger might detonate
ftfy

These kinds of setups are still prevalent in the aircooled VW world, because A. they look cool and B. they work without major carb work.

>The downside is that the fuel tends to corrode the turbine wheel
Corrosion is a chemical reaction. What actually happens when you put a carb before a turbo is that the droplets hit the compressor wheel, and those droplets slowly but surely blast away material (kinda like sandblasting, but with fuel).

The whole downside of direct injection is it's lack of vaporisation. Putting injectors as far away as possible promotos the vaporisation that is critical for optimal performance. An extreme example:

youtube.com/watch?v=q7FSrJ-FZFI

>because it doesn't become an issue until after the expected lifespan of the car.
Not all systems do this. Some systems actually need cleaning beforehand, and some even do within the warranty period.

It's not critical in some situations where stratified charge is viable.

For all of the situations (cold idle, high load low RPM, etc) where you don't want direct injection you can achieve the same effect with port injection.

All blown drag-racing engines use mechanical fuel injection (constant-flow) and have multiple injectors (>8 for a V8) with some below above the blower and some below.

Still you do not know where the gas will go and vaporized gas is very easy to ignite, between continuous operation and sheer luck you will probably get a fire.

Kek

Well, technically they eject fuel from the body of the injector, right?

If it fell into the ports where the fuel injector sits it'll be in your cylinder where it will be incinerated. Theres no possible way it can go into your supercharger

Fuel injected before an SC is classic tuning. The fuel cools the air as it evaporates and increases SC efficiency by closing the clearance between the rotors and alook closing the rotor to housing clearance.

Of course this is for non intercooler applications.

>Ever heard of putting fuel ejectors before a supercharger/turbo?
wat?

This only applies to Top Fuel. Not All blown drag race V-ates use mechanical injection.

Unless you have a massive boost leak or a backfire, no, it probably won't ignite.

>supercharger

why

>No intercooler
>No similar boost pressure
>No valid comparison
Why

Sorry, you're right. What I should have said is "erode the compressor wheel." I stand corrected.

No, you won't. Your spark and exhaust temps are both going to be around 1000-1500 *F. Your compressor housing temperature is going to be in the 200-300 range. It has comparatively little heat coming in, and it gets a lot of cooling from airflow and oil and/or water cooling. If the intake charge would combust the first time it contacted something that comparatively cool, you would get massive knock as the intake charge comes in contact with the exhaust valve, which never really cools down below 500-700 *F during normal operation.

the turbo doesn't have an intercooler either, and they are BOTH tuned at 11 psi

retard

except gas turbines are not piston engines

If the turbo didn't have an intercooler, then why is the turbine on the right side of the engine bay and the intake plenum goes to the left corner of the engine bay

Checkmate, atheists.

>I have absolutely no understanding about turbocharger piping whatsoever

dumb, inbreed, harleycuck

>tuning to PSI and not air density
Well there's your problem.