Big cam in a 402 LS2 stroker, how to tune?
Big cam in a 402 LS2 stroker, how to tune? This is the biggest cam that I have ever had, by far. What are the typical items that I should tune having this big cam? By comparison, the cam in my LS1 was a very driveable 218/218....
I want to add that the engine seems to idle OK for the 1 to 2 minutes that I have let it run, but with alot of lope,,, but then what can I expect from this cam.
I want to add that the engine seems to idle OK for the 1 to 2 minutes that I have let it run, but with alot of lope,,, but then what can I expect from this cam.
Last edited by Doc99SS; Mar 22, 2008 at 04:20 PM.
First, you need tuning software and a good datalogger. If you tuned your previous setup that is a plus. Second, are you looking for anything specific or just some direction to get started?
The basic principles for tuning a heads/cam stock cube motor apply to a 402 stroker with a bigger cam. Because of the increased cylinder volume pushing (or pulling) more air, expect to adjust the parameters alot more compared to a stock cube motor to compensate for the difference. I would start with cold start and idle, then move to warm idle and part-throttle driving. I save WOT tuning for last. Above all, take your time and be patient.
The basic principles for tuning a heads/cam stock cube motor apply to a 402 stroker with a bigger cam. Because of the increased cylinder volume pushing (or pulling) more air, expect to adjust the parameters alot more compared to a stock cube motor to compensate for the difference. I would start with cold start and idle, then move to warm idle and part-throttle driving. I save WOT tuning for last. Above all, take your time and be patient.
Thank you for the advise. Yes, I am looking for general direction. I have an old version of LS1Edit and ATAP. I have tuned my '99 with this combo in the past. I acquired this tuning software way back in 2001. And now, I have a wide band O2 sensor to help out, especially at WOT.
So far I have ajusted the size of the cylinder for this 402. I have altered the injector flow table for the FAST 39#/hr injectors that I installed. And I have bumped the idle RPM to 900 RPM. For this size cam, is 900 RPM advisable at wark idle? So far, the cold and warm idle seems just fine. Of course, I start the cold idle at 1100 RPM and by 132*F, the commanded idle speed is 900 RPM.
Well, I am off work today. So I will get a chance to start with data logging.
So far I have ajusted the size of the cylinder for this 402. I have altered the injector flow table for the FAST 39#/hr injectors that I installed. And I have bumped the idle RPM to 900 RPM. For this size cam, is 900 RPM advisable at wark idle? So far, the cold and warm idle seems just fine. Of course, I start the cold idle at 1100 RPM and by 132*F, the commanded idle speed is 900 RPM.
Well, I am off work today. So I will get a chance to start with data logging.
Staging Lane
Joined: Aug 2005
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From: USA
1000-950 RPM idle for tuning purposes is where I start at for most off the shelf roller cams. The trick is to find where your factory narrow band Oxygen sensors are cycling properly and line up with your wide band AFR. Depending on the size of the cam, a global change in the spark table of say, +2 degrees, of timing may provide improved performance and a more stable AFR. The "street" method involves looking for the maximum vacuum in the idle and light cruise state. Save WOT/Power tuning for the dyno.
Thank you for the advise.
I went for a very short drive and data logged. I am running 23% LTFTs in FTC 20 (cold idle) and about 15% LTFTs in FTC 10. Basically, I am running positive LTFTs in all FTCs. I know that the MAF curve is correct (I spent alot of time tuning that curve couple years ago with the LS1 engine), and I have the correct (as correct as I can be) flow for the new injectors. Besides the MAF table and the injector flow table, another method to correct the LTFTs is to modify the MAP table.
I am running the factory stock MAP table for a '99 Camaro SS with the original LS1 engine. Now that I have the LS2 short block in there, I'm thinking that I should be modifying the MAP table. Should I increase all cells in the MAP table 15% for starters?
I went for a very short drive and data logged. I am running 23% LTFTs in FTC 20 (cold idle) and about 15% LTFTs in FTC 10. Basically, I am running positive LTFTs in all FTCs. I know that the MAF curve is correct (I spent alot of time tuning that curve couple years ago with the LS1 engine), and I have the correct (as correct as I can be) flow for the new injectors. Besides the MAF table and the injector flow table, another method to correct the LTFTs is to modify the MAP table.
I am running the factory stock MAP table for a '99 Camaro SS with the original LS1 engine. Now that I have the LS2 short block in there, I'm thinking that I should be modifying the MAP table. Should I increase all cells in the MAP table 15% for starters?
Last edited by Doc99SS; Mar 24, 2008 at 09:19 PM.
