Secondary injectors

Wolf_Tm250 · Post by **Wolf_Tm250** » Sun Aug 27, 2006 2:12 pm

Hello all.

I think it's now the time for me to upgrade my injection system.

Engine is a Japanese 2000cc turbo.

Stock it has 4 x 540cc/min inj's ( 2 holes ) in the head, 4" before the intake valves.

Currently I have 4 x 850cc/min ( 1 hole ) in the stock position.

One thing I immediately noticed it was that the worst nebulization of the bigger, and 1 hole, injectors costed me some spool up and low end torque.

But now I'm around 85% duty cycle @ 1.4 bar turbo, and I definitely need more fuel.

Instead of changing to bigger injectors ( 1000 cc ) in stock position,
I'm thinking about re-put the stock ones ( 540cc/min ) in the stock position AND:

a) make an holder in every intake runner, 6" back the stock injector, just in the runner 90 deg. turn, where the runner becomes straight to go in the head, and put 440 cc/min - single hole - injectors

Total: 540 + 440= 980 cc/min

b) MORE SIMPLE: put 2 x 850 cc/min - single hole - injectors in the 2.75" steel pipe I have just before the throttle body.

Total 540 + 425 = 965 cc/min

Given that b) is much more simple to do, and I have no experience in secondary injectors placed BEFORE the TB, I ask you if it's a good option/idea, and with what pros/cons.

Even if I suspect option a) could be better...

Thank you.

bill jones · Post by **bill jones** » Sun Aug 27, 2006 4:19 pm

-I did a manifold just like what you are talking---added auxiliary injectors in a Subaru several years ago.
-So I called the guy to see how it ran---has never ran it yet.
---------------------------
-But he did say he's done the same exact thing on a turbo'd VW rabbit engine---and he says that he had to raise the fuel pressure substantially higher to get the fuel to evaporate well enough it didn't just wash into the cylinders.
-Apparently he used the same fuel pump as he was using on the primary injectors---but installed a higher pressure regulator to the auxiliary injectors someway.
-------------------
-And it ran real good once he got the elevated secondary fuel pressure right.
------------------------------
-I didn't quiz him any more that this info.

Wolf_Tm250 · Post by **Wolf_Tm250** » Sun Aug 27, 2006 7:38 pm

bill jones wrote:
-Apparently he used the same fuel pump as he was using on the primary injectors---but installed a higher pressure regulator to the auxiliary injectors someway.
-------------------
-And it ran real good once he got the elevated secondary fuel pressure right.

Very interesting....

thank you !

Wolf_Tm250 · Post by **Wolf_Tm250** » Fri Sep 01, 2006 4:41 am

At last I choose the simpler way....

in place of my current Denso 850cc/min - 1hole - side feed injectors, I'll put a Top feed fuel rail with Delphi Racing 1000cc/min - 6 holes - injectors ( unfortunately pintle type )...

Bye

Ed-vancedEngines · Post by **Ed-vancedEngines** » Fri Sep 01, 2006 5:15 am

Hello,
Can your EFI Management system support what is called "Staged Injectors"? Staged Injectors normally just run with the regular main injectors until either high load (Low vacuum) or high Boost (Turbo) activates the secong stage of injectors. This is done quite a lot with Mazda Roteries that are using both a leading and a trailing injector. It is also being tried some in a few V-8 's with the second stage getting used only for extra fuel only when it is needed.

With staged injectors the map wil have two parts in the same window when looking at the tuning curve on a laptop. They will require a different tuning than will the primary injectors but the additional tuning is there in the second part of the screen on the right side. That is for the second set of injectors that are the staged set.

Most all of the Haltech EFI Management systems do have the option of setting it up with staged injectors in addition to the primary injectors.

Maybe that would be a way to do it.
Ed

Wolf_Tm250 · Post by **Wolf_Tm250** » Fri Sep 01, 2006 5:41 am

Hi Ed,

yes, my Motec supports it...

btw, I choose to put bigger primary injectors... have a secondary stage of injectors would be a HUGE job.... modifying the intake manifold to suit them...

NRoshier · Post by **NRoshier** » Fri Sep 01, 2006 5:53 am

Modifying the intake manifold may not be that complicated. I have an article in the next issue of Race Magazine about Jamie Augustines Sports sedan Ford Escort, which is powered by a YB Cosworth engine. He uses high/low injectors with a very well developed phasing method. From the information that he has provided for the article it is certainly a worthwhile venture.

Wolf_Tm250 · Post by **Wolf_Tm250** » Fri Sep 01, 2006 6:04 am

Hi NRoshier,

I know you're 100% right, and that it would be the optimal solution to have 2 injectors' lines... better atomization at low rpm, and correct inj duty cycle at top/max boost that allow the optimal injection timing ( more power )...

btw I WORK sometimes !

..... so the time to make this jobs is small... and I already lost 2 years to finish my current engine !!

NRoshier · Post by **NRoshier** » Fri Sep 01, 2006 6:24 am

I know of 3 race engines where the owners have bought a intake manifold from a wrecker, cut out the injector bosses and 'machined' them to suit in a bench drill (using sandpaper). a hole is then drilled into the manifold and shaped with a burr. The injector boss is then glued into place with JB weld.
Should you wish, you can email me and I will send a partial copy of the article.

Wolf_Tm250 · Post by **Wolf_Tm250** » Fri Sep 01, 2006 6:40 am

Please send me it here: wolf_tm@tre.it

Thank you !

NRoshier · Post by **NRoshier** » Fri Sep 01, 2006 7:15 am

Article sent, let me know if it gets there.
If there is sufficient interest then I will post the pdf here after the issue is released.

Wolf_Tm250 · Post by **Wolf_Tm250** » Fri Sep 01, 2006 7:48 am

Received...

WOW fantastic article, Neil...

thank you very much!

NRoshier · Post by **NRoshier** » Fri Sep 01, 2006 10:19 pm

well just realised I do not know how to attach it![/img][/list]