Staged injection with itb

[timmyD]

Hey guys

Does any one have any experience with staged injection when running itb

I find it interesting

[Chr1s]

What do you want to know?

I don't have experience with it but can try answer your questions.

[timmyD]

I just think its a cool idea

You don't see to many set ups I'm guessing due to expensive ecu needed to run it smoothly

And difficulty with tuning

Was just seeing if any one was playing with this set up really

[Chernoby1]

Just to clarify, you mean putting one injector after the TB and another at the back of the intake plenum, so youd have 8 injectors for a 4cyl engine yea?

The idea was popular back in the day. Coz of the distance and fact the 'secondary' injector went through the TB youd get a nicer mixture and stuff like that.
The reason you dont see this setup much nowadays is because injector tech has gotten much better. These injectors however arent cheap... but then again neither is a custom made intake plenum with provisions for a row of injectors within it ;)

I was tempted to run this setup on my other car (turbo 3cyl) but decided to just buy the better injectors hahaha. The tuning side of things wouldnt be too bad, but then again every car ive bought ive whacked in one of those 'expensive' ecu's.

Retrofitting direct injection... thats the way to go ;)

[Chr1s]

You may be confusing direct injection advancements over the reasoning for standoff injectors,

Standoff injectors as mainly seen on drag cars/race cars (that have no efficiency ruling for fuel) run them for the benefits of cooling the charge precombustion. Tuning them is dependant on a few things as usual (airboxed or not, engine characteristics, etc) but is generally a cross over point for primary to secondary to reep the benefits of standoff injection at high rpm. Primary injectors are used for low engine speeds where you would probably need near 80% duty (just pulling a number out of my arse, you get the idea) to get the thing to idle with standoffs.

Injector placement is still not confirmed by theory, many teams especially BTCC spend plenty of time testing with injector placement, sometimes they even fire them at odd positions and yields the best results.

[timmyD]

Yes i was talking about standoff injectors so a second bank of injectors to come on in the higher rpm. Iv seen the set up with itb never looked into it with a plenum set up

The benefits of this in My understanding was a cooler and better atomised fuel mixture

I don't see the tuning to be real hard but it would surely take some time to get the transition and best place on the rpm range for the transition to its optimum

In the age of turbos and easy HP I feel like this sort of experimenting gets lost

[Chernoby1]

You may be confusing direct injection advancements over the reasoning for standoff injectors,

Standoff injectors as mainly seen on drag cars/race cars (that have no efficiency ruling for fuel) run them for the benefits of cooling the charge precombustion. Tuning them is dependant on a few things as usual (airboxed or not, engine characteristics, etc) but is generally a cross over point for primary to secondary to reep the benefits of standoff injection at high rpm. Primary injectors are used for low engine speeds where you would probably need near 80% duty (just pulling a number out of my arse, you get the idea) to get the thing to idle with standoffs.

Injector placement is still not confirmed by theory, many teams especially BTCC spend plenty of time testing with injector placement, sometimes they even fire them at odd positions and yields the best results.

Think you misread what i was trying to say (or maybe i just dont know how to explain things :D). I was just trying to say that newer injectors (not just DI-injectors) have better sprays than the older ones. While yes there is still benifits over a single injector setup, its no longer as large as back in the day. Sure for a race car it makes sense, but for anything else... is the 1-2% gain worth it?

The DI comment was only to state id rather spend my time retrofiting a DI system to my car rather than trying standoffs and all the crap thats required to run it, nothing about which is 'better' (i have no expirience with either so yea).

and re: odd placement, hahaha ive seem some setups with injectors firing like 150Deg perpendicular to the TB (more or less backwards).


Yes i was talking about standoff injectors so a second bank of injectors to come on in the higher rpm. Iv seen the set up with itb never looked into it with a plenum set up

The benefits of this in My understanding was a cooler and better atomised fuel mixture

I don't see the tuning to be real hard but it would surely take some time to get the transition and best place on the rpm range for the transition to its optimum

In the age of turbos and easy HP I feel like this sort of experimenting gets lost

I meant itb setups wih a plenum ;)

As for why not many people are trying this sort of stuff out anymore, many reasons for it one of which is pretty simple; how many sporty NA cars have been released in the last 15 years? ITB's and turbos is annoying enough, let alone adding standoff injectors and thus having to do some proper analysis on the intake chamber to work out flows/pressure rates and assessing whether the fuel will clump or stay atomised. Massive ceebs even though you can do half the job with cfd/fea/ect.

also, back in the old days, the world didnt revolve around money so much and people had more free time to tinker ;)

[Chr1s]

How would you retrofit DI on a K/B/D series? We don't have the headwork to allow for a real setup? Or do you mean liquid injection LPG? :D :D :D :D

I don't think atomisation is a big thing for the standoffs unless 1980 injectors were like garden hoses, I still think it's the fact of precooling without meth/water injection. Why don't you see it on the street? Because the EPA would absolutely destroy your arse over it LOL

I'd love to see your environment setup for CFD of the fuel injector and port flow :D

[Chernoby1]

For my F6A:
injector must sit on a slight angle and must use a very thin spark plug so they can both fit in the current space occupied just by the spark plug. If using a traditional spark plug, yea not gonna work. If using a plasma style spark plug you can get them thin enough to make it happen.
Havent really bothered looking into doing it with k/b/d's but if valve actuators become available in like 3-5 years i think id give making my own head a crack. Hardest part of the head is cam placement by far (imo)


By older injector i meant single port vs something like my new F6A injectors that are 8 port (and at only 325cc, pretty epic lol)

[Chr1s]

You sir are one crazy mofo!

[Chernoby1]

unfortunately i dont have much time or money to dedicate to these sorts of projects hahaha. One day (hopefully).

[trism]

Standoff injectors are really only good for high RPM, as at low rpm they just dribble into the trumpet, causing poor atomisation. At high sustained revs theres plenty of air being pulled into the cylinder, so they work well. If youve ever heard a V8 supercar at low revs, like when theyre driving through pit lane, youd know what its like.

On a road car itd just be wank factor.

If you had a dual purpose road and track car, youd run dual injectors, with high flow stand off injuctors that come in above say 4k and below that have standard injectors down at the base of the manifold that cover the low revs.

[curtis265]

Just to clarify, you mean putting one injector after the TB and another at the back of the intake plenum, so youd have 8 injectors for a 4cyl engine yea?

The idea was popular back in the day. Coz of the distance and fact the 'secondary' injector went through the TB youd get a nicer mixture and stuff like that.
The reason you dont see this setup much nowadays is because injector tech has gotten much better. These injectors however arent cheap... but then again neither is a custom made intake plenum with provisions for a row of injectors within it ;)

I was tempted to run this setup on my other car (turbo 3cyl) but decided to just buy the better injectors hahaha. The tuning side of things wouldnt be too bad, but then again every car ive bought ive whacked in one of those 'expensive' ecu's.

Retrofitting direct injection... thats the way to go ;)
phoaaa good luck with that!

some interesting info here guys

[timmyD]

Standoff injectors are really only good for high RPM, as at low rpm they just dribble into the trumpet, causing poor atomisation. At high sustained revs theres plenty of air being pulled into the cylinder, so they work well. If youve ever heard a V8 supercar at low revs, like when theyre driving through pit lane, youd know what its like.

On a road car itd just be wank factor.

If you had a dual purpose road and track car, youd run dual injectors, with high flow stand off injuctors that come in above say 4k and below that have standard injectors down at the base of the manifold that cover the low revs.

I guess that is where the cost comes into it
Having a ecu that can handle another set of injectors and a second map means they are normally a top shelf item