DOD Cam Swap (formerly known as Preliminary Feedback On New Era G8GT Cam in an LS4)
07-07-2010, 12:09 AM
#90
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not sure when that will be, you'll have to get with Nate about that. He's about to have a son any day now so who knows when that will be. Plus, this hot air isn't going to be good for setting any records. He was damn close on the tune though only about 5% off. I can tell you that it pulls like a raped ape in the 5-7K range, even with him and I weighing about 465 lbs combined.
07-07-2010, 11:11 AM
#91
not sure when that will be, you'll have to get with Nate about that. He's about to have a son any day now so who knows when that will be. Plus, this hot air isn't going to be good for setting any records. He was damn close on the tune though only about 5% off. I can tell you that it pulls like a raped ape in the 5-7K range, even with him and I weighing about 465 lbs combined.
07-07-2010, 02:42 PM
#92
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I'll put together some more updates later, but yeah it pulls like a mule from 5k-7k, and isn't down much at all between 4k-5k. Power peaks between 6000-6500. I seriously could have gone with 3.69s with this cam and been just fine, because DOD likes revs too (like a 4 banger does, shocking I know), and I doubt I'd hurt my mileage (which is about the same, except that I now can burn a lot more gas, lol). I'd say the optimum shift point is around 6800-6900RPM for 1-2, and 6600-6700RPM for 2-3.
Also, this cam is getting choked off at the top. Vacuum hits 2-3kPa around 4000, then climbs to 5-6kPa up top. The MAF and TB are probably a little bit too small. To realize the cam's full potential, I'm gonna need to port the heads and bump compression. Sorry, but that's not happening any time soon because I'm already down an income stream (wifey) and I'm about to be up a mouth to feed. Longer term, I'm also probably going to want to upgrade at least my rod bolts, and maybe upgrade the rods and go with lighter pistons. I haven't done any research on that yet, because I'll just torment myself into spending money that I don't want to right now.
None of this bothers me in the slightest (I am actually enjoying this quite a bit), but I don't want anyone else thinking about this cam to be suprised.
My final comment for the moment is that launching shouldn't be a problem now that I've got my spark tuning maybe 75% done (the last 25% is going to be hard without a dyno). The engine operates in a much different g/cyl range than it used to, and I was getting sharp transitions that was bringing power in and out.
Also, this cam is getting choked off at the top. Vacuum hits 2-3kPa around 4000, then climbs to 5-6kPa up top. The MAF and TB are probably a little bit too small. To realize the cam's full potential, I'm gonna need to port the heads and bump compression. Sorry, but that's not happening any time soon because I'm already down an income stream (wifey) and I'm about to be up a mouth to feed. Longer term, I'm also probably going to want to upgrade at least my rod bolts, and maybe upgrade the rods and go with lighter pistons. I haven't done any research on that yet, because I'll just torment myself into spending money that I don't want to right now.
None of this bothers me in the slightest (I am actually enjoying this quite a bit), but I don't want anyone else thinking about this cam to be suprised.
My final comment for the moment is that launching shouldn't be a problem now that I've got my spark tuning maybe 75% done (the last 25% is going to be hard without a dyno). The engine operates in a much different g/cyl range than it used to, and I was getting sharp transitions that was bringing power in and out.
Last edited by nmp0098; 07-07-2010 at 04:33 PM.
07-07-2010, 03:04 PM
#93
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Crap, the injector tables in an 08 Vette (LS3) are slightly different than those in an 08 G8GT. I just had Camaro on the brain and that isn't supported until HP Tuners 2.24 (and the 2.23 beta, which I don't have). I'd rather get those right than bake the error into my MAF and VE tunes...
07-07-2010, 03:36 PM
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Crap, the injector tables in an 08 Vette (LS3) are slightly different than those in an 08 G8GT. I just had Camaro on the brain and that isn't supported until HP Tuners 2.24 (and the 2.23 beta, which I don't have). I'd rather get those right than bake the error into my MAF and VE tunes...
I can get you the beta if you want it? Or you can just email bill@hptuners with your serial number.
BTW, did you get that ve stuff figured out?
07-12-2010, 01:03 PM
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OK, so several things happened over the last week, and I'll try to lay some of them out.
Firstly, the fuel injector tables I ended up using were from an 09/10 LS7 Corvette. The LS3 has their tables scaled differently than the LS4/LS7/L76 do. The LS3 tables are different depending on whether you are looking at a G8 GXP, Corvette, or Camaro. The Corvette LS3 tables are setup for a return style system and threw my fueling off by 10%+. The L76 tables threw my fueling off by 4% or so, and had a different flow at 58psi than the Corvette LS3 and LS7. I decided on the Corvette LS7 tables because they had the same axis', the same returnless style tables, they didn't change my part throttle curves much at all from what I had previously tuned in, and I think the Corvette is a bad machine.
Once I worked that out, I finally dialed in my WOT MAF and VE curves. Tuning part-throttle VE on the E67 controller is very difficult, because of the 2nd order polynomials that replace the conventional VE table. I'm using the VE <> EQ 3.5 program, but the fact that a fit takes place means that you can't dial it in precisely. I found that just using the MAF to tune VE leads to about the same error as using a wideband because of the curve fitting issues, at least for street tuning. I was able to get WOT pretty darn close by carefully choosing the boundaries between the curve fits.
If you buy the theory that the torque curve and VE tables follow eachother closely, then I'm making peak torque around 5600RPM (+/- 200RPM) at about 104.5% VE (+/-1%). The stock VE and new VE cross at around 4400 RPM.
I've found that my MAP sensor reads about 2kPa lower than Barometric when the engine is off, so I see atmosphere up to about 4400RPM and then vacuum climbs to about 4kPa, so I'm seeing some inlet restriction on the top end, but not much. I figure that there is maybe 1-2% more power left on the table based on the VE curves, so I'm not too worried about it at the moment.
HPTuners 2.23 unlocks a bunch of tables that I have seen in 05/06 tunes, but not in the 07/08s. Some were altogether new. There were a couple particularly useful tables that I used to get rid of my drop throttle surging and clean up my transmission's performance. If you have an 07+ and use HP Tuners, you should probably email support@hptuners.com and request the Beta.
I also took the time to put header wrap on the crossover, port match my TB adapter to the manifold and TB (it's not perfect, but it's better than it was), and do some mild porting on the TB.
I also had the cutout installed. I'm not sure I like the cruising tone through the cat and res (I mounted it where Panther427 and others have), but it sounds pretty good at WOT. If nothing else, it's loud. This video doesn't do the bass justice, but it comes through pretty well. This was taken with the car running open loop, and in the middle of tuning, so it kinda falls out of the pretty smooth fast idle I had going on (800RPM) into loping and back. One day I'll flash in the stock cal, and if I can get the engine to start you can hear just how nasty the idle can be if I wanted to deal with stalling and surging.
http://www.youtube.com/watch?v=MnSDagOWXhc
Firstly, the fuel injector tables I ended up using were from an 09/10 LS7 Corvette. The LS3 has their tables scaled differently than the LS4/LS7/L76 do. The LS3 tables are different depending on whether you are looking at a G8 GXP, Corvette, or Camaro. The Corvette LS3 tables are setup for a return style system and threw my fueling off by 10%+. The L76 tables threw my fueling off by 4% or so, and had a different flow at 58psi than the Corvette LS3 and LS7. I decided on the Corvette LS7 tables because they had the same axis', the same returnless style tables, they didn't change my part throttle curves much at all from what I had previously tuned in, and I think the Corvette is a bad machine.
Once I worked that out, I finally dialed in my WOT MAF and VE curves. Tuning part-throttle VE on the E67 controller is very difficult, because of the 2nd order polynomials that replace the conventional VE table. I'm using the VE <> EQ 3.5 program, but the fact that a fit takes place means that you can't dial it in precisely. I found that just using the MAF to tune VE leads to about the same error as using a wideband because of the curve fitting issues, at least for street tuning. I was able to get WOT pretty darn close by carefully choosing the boundaries between the curve fits.
If you buy the theory that the torque curve and VE tables follow eachother closely, then I'm making peak torque around 5600RPM (+/- 200RPM) at about 104.5% VE (+/-1%). The stock VE and new VE cross at around 4400 RPM.
I've found that my MAP sensor reads about 2kPa lower than Barometric when the engine is off, so I see atmosphere up to about 4400RPM and then vacuum climbs to about 4kPa, so I'm seeing some inlet restriction on the top end, but not much. I figure that there is maybe 1-2% more power left on the table based on the VE curves, so I'm not too worried about it at the moment.
HPTuners 2.23 unlocks a bunch of tables that I have seen in 05/06 tunes, but not in the 07/08s. Some were altogether new. There were a couple particularly useful tables that I used to get rid of my drop throttle surging and clean up my transmission's performance. If you have an 07+ and use HP Tuners, you should probably email support@hptuners.com and request the Beta.
I also took the time to put header wrap on the crossover, port match my TB adapter to the manifold and TB (it's not perfect, but it's better than it was), and do some mild porting on the TB.
I also had the cutout installed. I'm not sure I like the cruising tone through the cat and res (I mounted it where Panther427 and others have), but it sounds pretty good at WOT. If nothing else, it's loud. This video doesn't do the bass justice, but it comes through pretty well. This was taken with the car running open loop, and in the middle of tuning, so it kinda falls out of the pretty smooth fast idle I had going on (800RPM) into loping and back. One day I'll flash in the stock cal, and if I can get the engine to start you can hear just how nasty the idle can be if I wanted to deal with stalling and surging.
http://www.youtube.com/watch?v=MnSDagOWXhc
07-13-2010, 04:24 AM
#99
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well, a cam of that size is going to want lots of high rpm breathing. The LS6 intake isn't at it's best above 6500rpm however it will work up there and I'm still suspecting that that TB and maf might be a restriction. As far as the heads I would recommend larger intake valves and some porting. The biggest problem I see is the rpms required to take advantage an overly large cam. 7K+rpms are asking for trouble. Upgraded rod bolts will probably buy you a few hundred rpm
07-13-2010, 11:46 AM
#100
If this cam is too big, what would be a more docile DOD compatible cam?
My application will have a vehicle weight of 2800 lbs, a manual tranny with stump pulling gears, and a proper set of long tubes with under 5 feet of exhaust past the collectors.