Twin Hole Vs Single Hole Injectors

[SimonR32]

Does anyone have any comments, I have heard opinions that twin holes are not as good... I'm assuming this is because the 2 spray patterns would collide and condense the atomised fuel?!?

The reason I ask is because is have the option on 700cc single feed or 800cc twin feed and am wishing to go the larger as i don't want to run the risk of running too close to 100% duty cycle.

Also does anyone have any opinons on porting rb26 heads?!? I have seen a lot of conflicting evidence to if it is really worth it or not...

cheers simon

[J_Red33]

From the best of my knowledge:

Twin spray injectors should be a better setup as long as they don't spray a solid jet of fuel rather than an atomised spray.

The biggest advantage with going twin spray is that if they are set up correctly they will spray the atomised fuel directly down the intake ports to the valves.

The biggest problem with single spray setups is that fuel collects on the sides of & in between the ports & is therefore no longer properly atomised. It very much comes down to the quality of the injector & how well it's set up more than anything.

Not 100% on this, but from what I know that's the key points

[T04GTR]

also worth mentioning the injectors spray when the valve is CLOSED. not open.

this is so it has a chance to atomise on the nice hot valve.

[FATGTS-R]

My Rb20 had GTR injectors (single pintle) and although it made decent power the tuner was not happy with the tune at anything other than WOT. I thought it drove fine.

Its over my head, but somehow he pointed at the injectors as the culprit, which had just been recoed and were in good working order.

So in went a set of quad orifice bosch items from APS that were designed for the xr6t and rated somewhere around 500cc I beleive.

He told me that with these in it was so much easier to tune and gave a result he was happy with.

When I got it back, it was as he said it would be and was a smoother running tune. Where I noticed the diference the most was at cruising speeds with very small throttle openings, it was much crisper to respond with the new items and economy improved by approx 0.5L/100km.

After all that, I couldnt say if one is better than the other as I am not technically adept enough to understand the workings of each but in my own personal experience I had positive results switching from the single pintle type to quad orifice type.

The tuner was also adamant that the older style pintle types were robbing me of drivability and I was not charged for the new items.

[T04GTR]

i have a 34 box SEE MY SIG

[paulr33]

this was discussed a while ago

i think spray patterns means jack all and doesnt add any value

[J_Red33]

this was discussed a while ago

i think spray patterns means jack all and doesnt add any value

Hmmm kinda doubtfull about that myself. I've heard stories of a mate of mine with motorbikes also & it was the diffence between it running properly & barely at all!! Motorbikes are genrally pretty highly tuned sensitive beasts so I'd say it becomes more important the more warmed up your engine is when it comes to power output.

Better mixed fuel & air burns much faster. You can ignite petrol just poured on the ground & it just burns, spray a fine mist of it into the air though & then try to light it & ........... Be somewhere else if some idiot actually tries this!!!

Would be interesting to see if anyone has actually done some back to back dyno testing on this.

Edited September 4, 2006 by JazzaR33

[carl h]

ive found that using disc type injectors instead of pintle syle (as std) will result in strange idling and interesting cruising...

[J_Red33]

ive found that using disc type injectors instead of pintle syle (as std) will result in strange idling and interesting cruising...

What kind of 'disc type' injectors did you have? It is important to know that even though the outlets of these types of injectors can look the same, they can spray very different patterns depending on what kind of engine they are designed for.

Spray patterns can vary in with & direction that they are sprayed. Injectors like the standard type on an R33 GTS-t for instance do spray in 2 pairs (many have 4 holes in the outlet, 2 hole ones are also common but there are other variations than this) ie 4 holes in the disc spraying into 2 directions for 2 ports. Others however like say a VT commodore, have what appears to be basically the same setup but only spray in a single direction.

The biggest advantages from these types of injectors in my experience, are that the give a better directed spray, while actually atomising better than direct pintle outlet injectors. They can vary in spray width and in the case of twin spray setups also spray angle. If you are using the wrong type of injector for the application it may not work quite so well.

[Mr. Oizo]

I was under the impression that the disc/ball style injectors had better atomization, and could stay at higher duty cycles for much longer than standard type injectors..?

6 Holes should have better atomization, than single or twin holes.

[carl h]

i had a set of rc branded lucas injectors to suit a 7mgte, had 4 holes in the cap but it was recessed back into the injector body a touch so i think thats perhaps why it ran so strangely.

[Mr. Oizo]

i had a set of rc branded lucas injectors to suit a 7mgte, had 4 holes in the cap but it was recessed back into the injector body a touch so i think thats perhaps why it ran so strangely.

to quote someone from another forum:

"i hate lucas injectors. they suck. BUT, i would put lucas in before i would put rochestor. heck, i would WALK to avoid putting rochestor in my car. i would CUT OFF my legs, and get a wheelchair before i would put rochestor in my car. i would let chuck norris roundhouse kick me in the balls if i put rochestor in my car."

-i just realised that has nothing to do with the topic really

[carl h]

lol, well whatever i got them new for stupid cheap (200$ usd) and they do work...just behave strangely sometimes.

heres a good website on basic injector info... http://www.sdsefi.com/injectors.htm

never been a fan of domestic style (rochester) injectors, they always seemed big and chunky, plus they tend not to have many import applications.

Edited September 7, 2006 by carl h

[J_Red33]

i had a set of rc branded lucas injectors to suit a 7mgte, had 4 holes in the cap but it was recessed back into the injector body a touch so i think thats perhaps why it ran so strangely.

Mmmm not a real big fan of lucus injectors they tend to actually collect fuel on the side of the outlet due to them being set back so far like you said. Not a big rochester fan either. Newer design Bosch & Jecs injectors are probably the best I've delt with. Not so sure on some other aftermarket stuff.

[Cameron_Datto]

http://www.injec.com/techdata/tag-Injector...acteristics.pdf

[Mr. Oizo]

denso injectors are the only way

sard

blitz

hks

(most jap stuff)

even the rx7's are denso's...

[J_Red33]

denso injectors are the only way

sard

blitz

hks

(most jap stuff)

even the rx7's are denso's...

Toyota, Mitsubishi & Mazda use Denso

Nissan & Subaru use JECS

Honda & Suzuki different brands again (Can't remember the names barely ever saw them)

It's interesting that you pointed out about RX-7's having denso's. The injectors they use in particular on earlier models I did not like as they seemed to be very prone to broad varyations in flow between individual injectors & sometimes variations in flow of the same injector while they were running! This was especially bad under light loads. Good way of confusing an ECU. Rich no lean rich no no lean no Rich AHHHHHH.

It is a brand I did forget to mention however & they are good, but seem a bit more prone to developing problems too (leaks, dodgy spray patterns etc). They're newer high performance stuff I can't comment on.

[Mr. Oizo]

Toyota, Mitsubishi & Mazda use Denso

Nissan & Subaru use JECS

Honda & Suzuki different brands again (Can't remember the names barely ever saw them)

It's interesting that you pointed out about RX-7's having denso's. The injectors they use in particular on earlier models I did not like as they seemed to be very prone to broad varyations in flow between individual injectors & sometimes variations in flow of the same injector while they were running! This was especially bad under light loads. Good way of confusing an ECU. Rich no lean rich no no lean no Rich AHHHHHH.

It is a brand I did forget to mention however & they are good, but seem a bit more prone to developing problems too (leaks, dodgy spray patterns etc). They're newer high performance stuff I can't comment on.

I'm using FC RX7 550s

I had them cleaned and flow tested before I installed them

Before:

143, 138, 139, 138

After:

140, 140, 140, 140

I'm not sure what measurement they used, I actually only found out that the RX7 ones didn't have great quality control until after I bought them, I must have just bought a good batch of them.

[carl h]

i believe that the rx7 injectors tend to shoot more of a stream of fuel rather than a mist, least thats what i remember while looking round for uprated injectors.

[Mr. Oizo]

I'm hoping that is only the Lucas/PTE/Rochester injectors