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it's almost a alfa romeo spider
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Discussion Starter · #1 ·
i have 22 pound injectors on the car now..is it air flow, the ecu?
 

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It's not really a question of hp, since hp is increased through more than one factor. In this case, the question is how much of a correct mixture can you get with the L-Jet, and your new injectors?

The amount of air that goes into the mixture depends on how long the intake valves remain open, which is dependent on the intake cam. If you have modified the head and intake cam to allow more air, then you must add more gasoline to the mixture (to prevent the engine from running lean). The injectors spray the gasoline, but how long they are doing so is controlled by the ECU. The OEM L-Jet (I thought you had changed yours?) will only tell the injectors to spray gasoline for a certain period of time. Hence, between the ECU that limits the amount of time that the injectors are spraying, and new injectors that spray more gas than the stock ones, you must get enough gasoline into the mixture to get it right. Hence, if this is not enough it would seem that the way to increase the amount of gasoline is by having the injectors stay on a little longer, which is controlled by the ECU.

Best regards,
 

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bianchi1: 22lbs/hr injectors can support 160-180hp in an Alfa 2.0. L-Jet can easily support this.

I am not sure I understand the rest of your post. It's not like you can just put in bigger injectors on an otherwise stock engine and get more power. The engine puts the demand on the injectors, it's not the other way around.

Greg Gordon,
Silicone Hose Kits
OKINJECTORS.COM
 

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it's almost a alfa romeo spider
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i have put on the lh-jet,just as a fit and run,back to to the l-jet for now..i have a second head i am working on,with bigger cams and 45 intake and 38 exhaust valves so thats why i was wondering on the hp support of l-jet, i can go back to lh-jet in about 3 hours.with the bigger cams and the diff valves the hp will increase.. also cc the new head at 9.5/1 compression.the injectors where the easy part.
 

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it's almost a alfa romeo spider
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Discussion Starter · #6 ·
superflow....above..
 

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it's almost a alfa romeo spider
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Discussion Starter · #8 ·
..........10.9..........
 

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Slight drift off subject here..but related..I am planning to install a set of performance cams (IAP and Centreline have products with an 11mm lift and it will be one of these that I put in). My understanding was that the ECU would cope with the high lift cam without modification and only timing needed to be adjusted. Does the ECU need re-programming?
 

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As Eric said, the ECU can't be reprogrammed. (well, at least without a lot of dollars and a lot of risk anyway)
Neither can the ignition unless you go to an aftermarket setup swuch as RML, 123 and a few other offerings through various vendors and suppliers.
You could even revert to full on points~n~condensor w/flyweights if you desired as the ECU doesn't require the ICU to even be present, let alone functional, for the fuel side of things to work.

Tryign to change timing by fiddling with the distributor position will get you exactly nowhere as all advance and retard control is done via the ICU and the dizzy is literally nothing more than a 4 way switchbox in the L~jet system. As in, yeah, you can move the dizzy, but it won't effect timing at all.
 

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So, does the ECU effectively adjust to the airflow change of a modestly more agressive cam profile? .. or, is the cam mod something that is really only worthwhile with a carb equipped car where fuel mixtures can be more easily adjusted?
 

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The AFM can compensate decently if things aren't too radical.
No tweaks would be needed in the 11~ish and less lift ranges.
I think there's even a couple folks who have closer to 12mm and hot heads too that are doing just fine on stock ECU and ignition components. (Zunige being one IIRC)

Better have the fuel pump system in good order though onnaconna after a certain point a weak volume pump will hurt quite a bit as things lean out in the upper RPM range due to that weakness.
Good condition stock pumps with good electric flowing to them will suffice. Intermittant or voltage drops in the circut will not.
 

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Tks, as always. Plan A still intact....
 

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Richard Jemison
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Comments on FI cams & regulators

Some comments:
First, lift is no way to determine "size" of cams. You need to look at the full profiles! Most over the counter cams have way too much overlap for proper cam events, and too much fuel goes out the exhaust. That impacts both available fuel for combustion and O2 sensor output which cobbles the FI system. Since a fixed amount of fuel is available through the injectors proper cam design is important. FI cams are different from Carb cams.
As well loss of lower end torque is eliminated by correct cam design. Early duration is a problem of Alfa`s cam design as they are designed to last a long life with only moderate metal hardness. (soft ramp rates, seating ramps)

Fuel pressure can be increased SLIGHTLY without impeading the FI function, giving more ultimately available fuel for upper end. This can be acheived by massaging the stock pressure regulator.

The stock pressure regulator with good pump should indicate a minimum of 25 lbs with vaccuum, 30 lbs without.. My GTV6 stock indicated 35 with vac, 40 without(open throttle).

The fuel availability, and proper fuel management in the engine, allows more HP with given fuel.
 

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... I think there's even a couple folks who have closer to 12mm and hot heads too that are doing just fine on stock ECU and ignition components. (Zunige being one IIRC) ...
No, not with a stock configuration... I do have 12 mm cams (and a modified head), but the stock L-Jet cannot handle these mods under load. Under 3k RPMs and / or if increasing speed gently and steadily the L-Jet keeps up, but under the smallest load above 3k RPMS, whether going slightly uphill or depressing the accelerator to increase speed, the car will run lean, ping, etc. (I have also seen this situation in a friend's 1984 Spider that was running with 11 mm cams.) The L-Jet is not a programmable unit and the stock set-up has always had that limitation.

Best regards,
 

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Any comments on the Centreline or IAP products with regard to profiles? ..or another source maybe?
 

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Discussion Starter · #19 ·
zunige.. what size injectors are they useing? stock? those are only 16 lbs injectors, that would make it ping, sputter..
 

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zunige.. what size injectors are they useing? stock? those are only 16 lbs injectors, that would make it ping, sputter..
Yes, I am talking about putting high lift cams (11 mm or higher) with an all stock set-up - and all OEM components working as they should.

Over the years I have slowly upgraded the cams in my 1984, but with each upgrade, there are more things to consider, not to mention the financial aspect. Thus, based on Darren's comment about me running 12mm cams, I didn't want anyone to think that they could just add the cams to a stock set-up and everything would be OK.

Best regards,
 
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