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Aggressive Cam tuning questions GM L33 5.3

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I have recently dropped in a 2005 Chevrolet Silverado L33 all aluminum 5.3 Vortec engine an RX-8, LS style aluminum typhoon intake, long tube headers, mated to a full billet 4L80E auto trans, problem is other than mild Cobb Tuning with Subaru's this is the first real tuning I'll be doing with HP Tuners, not gunna lie I'm a little lost in it all. Where do I start to A) Help it idle and adjust for the aggressive cam lobes in it now, B) Its a Stage 4 Cam, will the aggressiveness of this drastically effect my MAF with aggressive overlap being its only 6" from the TB. Any help in the right direction to start this is appreciated, hopefully this isnt to vague of a question, just looking for somewhere to start to even get it idling reliably so I can drive and data log it.

You've really jumped in the deep end there! Tuning to suit a large cam is a reasonably advanced job that we do plan to cover in a worked example at some stage but I'll give you the general procedure:

1. If the cam is a reasonable size you're going to have trouble with the MAF. Personally I ran most of the large cams we did using the HP Tuners 1 bar SD OS. I'm not familiar with the L33 so I don't know what PCM it uses and whether it has a native VE table or runs the VVE system (I'll assume in 2005 it would be virtual VE). With the VVE system you have the option of forcing the PCM to run in SD and ignore the MAF. Regardless which way you go, the process of tuning the VE table is the same.

2. Getting good idle control is probably the hardest part of tuning a large cam. You're going to need to raise your target idle speed a little (how much will depend on the actual cam but I'd start with an increase of 200-300 rpm). This needs to be matched by raising the base running airflow to suit. You can create a histogram of airflow vs ECT to help fill in this table with realistic values.

3. If the engine is dbw throttle (again I'm unsure) you may also need to raise the 'Effective Area Percent Max' parameter that you'll find under the 'Idle' and 'Airflow' tab. The default value will be something lifke 2.46% and you may need to raise this a couple of percent to allow the engine to reach the idle target.

There's a little more to it but this should point you in the right direction. The worked examples in the reflashing course will still be useful to you when it comes to tuning the SD tables.

Let me know if you have other questions

I may have bitten off more than I can chew I can agree to that. I was following your worked example on the tuning the Bone stock 6.2 LS Holden, I was following along screen for screen and many of the options to modify are very close to the same. The L33 is an all aluminum 5.3L truck engine that has a version of the LS6 heads come from factory. It was rated at about 350hp vs the iron block 5.3 at about 300hp. Only the H.O. Chev half tons came with it. The cam I am running is 235/242 .621"/.592" 111+3 and is subtantially more aggressive than factory, prehaps again I may have gotten a little carried away. It is a DBW throttle and under the worked example I saw an option on the Holden for the Speed density option on your screen, however I am limited to three tabs in this airflow section, General, Dynamic and Electric Throttle. So I may need to switch ECM's if I want to change to Speed Density which from what I'm looking into may have to be the only route. I will try the things you have mentioned tomorrow morning and give some feed back as to how that makes out. Thanks for the quick reply and I am really enjoying watching the series! Good on ya mate!

I am battling a similar scenario 65 mustang I installed customer supplied 331 stroker powerdyne supercharger, I switched to efi with ls coils on aem infinity and after I got the car running I realized the oversized cam that is installed, I found that best idle I am getting is from running ve with tps reference, and ignition with map reference (thank you andre for that webinar on alpha-n), this engine literally has 0 vacuum at idle, not sure if this can help you in anyway but yes I forgot to mention I removed factory ecu A9L with a moates quarter horse and deleted maf in order to get control of this thing

Hi Hoapct, I'm glad that the webinar helped but I'd be a little concerned with what you're seeing on that particular engine. Generally with a supercharger you'd want to run a relatively conservative cam with limited overlap, otherwise essentially you can essentially end up blowing your intake charge straight out the exhaust during the overlap period. Zero vacuum at idle would suggest you've got an incredibly aggressive cam even for a naturally aspirated engine. I'd be checking the specs of the cam as well as confirming that the cam is dialled correctly.

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