nmp0098

I will eventually do some traction work, but since this is a street car and I do most of my accelerating from a roll, I want to finish adding power first.

I've decided to put off my dyno time until I'm actually done, and I've figured out that I won't be going to the track after work for a while yet. I'll get a more impressive time if I wait until Fall anyway. So, I've figured out a way to give you guys some idea of what kind of horror I've visited upon my engine.

This graph shows the 95kpa VE curve for the stock engine (Stock), the engine after the LS6 and CAI (LS6), and the engine as it stands now (Cam). Because the gear change makes a big difference in everything, I also reflected the curvese using the gear change (LS6_2 and Cam_2). These are NOT actual VE curves, just an indication of how the gear change effected the result at the wheel. I simply multiplied the VE by 3.29/2.93, and multiplied the RPM axis by 2.93/3.29. I'm NOT claiming that this is my torque curve or anything like that, but it does give you a good idea how things have changed. My other disclaimer is that the LS6 curve is approximate from the MAF, while the Cam curve is based on the WOT performance of the engine tuned at 80 degrees with a wideband.

[IMAGES DELETED DUE TO UPDATE BELOW]

From this, you can see why I complained about the loss of torque between 3000 and 4000 RPM. You can also see just how important it is to do the gear change before the cam change, because the car would suck without it. Finally, you can also see why I always claimed before the cam change that I could rip the tires free at pretty much any speed in 1st gear, and why I think I'll be fine launching with the stock setup right now (the Cam_2 and Stock curve are almost the same in the 2400-3500 RPM area, when you consider the effect of the gear change on torque at the wheels).

JDMC5

iTrader: (3)

very interesting nate. Just remember that a smaller cam/ different profile wouldn't have that loss down low. In order to take full advantage of that cam you really need some more mods to improve breathing up top. I would really consider a stall with this cam as well but I know your plans aren't to build a drag car. (I'm sure you know all this, just stating for the others benefit)

nmp0098

UPDATE: The Cam Was Advanced

So, I finally got to the point where thinking about advancing the cam became advancing the cam. The end result is that I moved the torque curve down 1000 RPM and picked up a ton of mid-range power at the expense of having an impressive top end.

I'm now shifting in the 6300-6400 RPM range, which kinda backs up my impression that I would have needed to shift several hundred RPM past 7000 RPM with the cam the way it was.

Here are updated pictures of how my mods have effected VE: (I took down the old pictures because a couple things had scewed them high... namely E10 and G8 injector data)



Again, with the axis zoomed in:


You can see that with the cam advanced, the engine is just a peakier version of stock. The engine currently makes a lot of midrange torque. When you compare the cam installed normally to installed with a lot of advance, that 5500ish RPM crossover point that you see in VE is backed up by acceleration numbers and other airflow estimates.

I probably could have retarted it a bit from where it's at now (2, maybe 4 degrees), to add a little more top end and shift at say 6500 RPM, but I would rather be where I'm at now then where I was. I won't be going into the engine just to get those couple degrees, but if I'm in there for something else I will probably do it.

With the advance, I've also moved intake valve close at 0.005" a lot earlier than stock, so dynamic compression is way up everywhere except for the top end. The engine sounds like it too; you can hear a bit more of that pop in the exhaust that you get with compression. Of course moving intake valve opening a lot earlier made the idle worse, or at least harder to control. I like a nasty idle, but the accessory belt doesn't (you can smell the protest) so we had to compromise.


Here, you can see where I took a perfectly good timing gear and had the cam dowel hole filled. The weld is nearly as hard as the case hardened part of the cam gear. The inside of the gear is putty in comparison. It was not fun to drill through.





Here is the gear out of my engine next to the modified gear. It's not perfectly lined up, but you can clearly see I made a substantial change to cam timing.





I took apart all of the usual suspects.





This time I only need to get at the gear, not pull the cam. The engine stayed more complete this time, as evidenced by my not messing the power steering pump hard line and a few other nasties, like the intermediate shaft and exhaust.





Front end shot.





Side view. I used 4 jackstands again for the cradle, but this time I just used jacks on the frame to get enough clearance to get at the dampener.





Here is the dampener coming off.





And I got to the timing gear through the top.





The car went together without issue. I used new gaskets this time. I had planned to freshen up the timing chain while I was in there until I figured out that you have to seperate the engine from the transmission to change the chain... the oil pump has to come out, which means the oild pick up has to be removed, which can't be done without removing the oil pan, which has bolts up against the transmission. I'll just hang on to the chain and dampener until the motor needs freshened up.

The MAF curve was still dead nuts, so all I had to change was VE and fuel injection timing. After that, I just had to do the idle and drivability stuff. It's running like a champ, and I can't wait for Milan to open. Even though I'm down on power, I think the car will run a lot stronger overall. I'm up on acceleration everywhere under 80 mph, which is all that counts in my daily life. I miss that top end, but I never really got a chance to use it. Now, if that 6 speed swap works out and someone wants to build the engine to spin to 7500 RPM, the cam would be perfect.

My final note is that DOD is a lot stronger now. So even though advancing the cam cost me some mileage under some steady state conditions, I can stay in DOD for more driving conditions. Overall, mileage is the same or better than it was before I advanced the cam. DOD is really like an extra overdrive, and having it on helps mileage because I drive to keep it in DOD. My right foot is gas mileage's worst enemy, but I worked hard to get my engine to the point where it could burn a lot of gas when I want to.

CenTexSS

iTrader: (2)

Good **** man. Any plans to dyno or hit the 1/4 mile? I'd like to see all your hard work come to fruition!

smokin06impala ss

iTrader: (2)

So that's what you have been up to hadn't seen post in awhile. Nice work!!!

nmp0098

JDMC5 has a line on dyno time for a decent price. I'm gonna get on there soon, but mostly to work on WOT tuning and part-throttle spark tuning and not to get hard numbers. The strips are still closed until around May up here. Something about snow...

Ha, it's mostly the kid that has kept me busy. I still get a lot done, I just have less time to spend on any one thing.

smokin06impala ss

iTrader: (2)

I hear you man !!!They keep us very busy.

JDMC5

iTrader: (3)

your killing me haha!!

JDMC5

iTrader: (3)

taking all that stuff off must have taken some time..........ahem. Nice jack btw.

fieroguru

iTrader: (1)

I am glad the advance modification worked out for you. I can't wait to see some dyno #s".

I am hoping by summer to have mine up and running with some #'s as well!

nmp0098

I made it to the strip on Saturday, and the results were improved by playing with the cam timing. I do think I overshot a little too much towards early valve events for how I want to drive the car, but it’s not too bad where it’s at. This way will definitely keep the lifters alive longer.

My best pass last year was 13.9 @ 105.8 with a 2.29 60’. I hit that a couple times with Lambda ~ 0.87, 26* at torque peak and 28* at power peak. This last time out I hit 13.5 @ 105.1 with a nearly identical 2.28 60’ using 0.87 and 24* at peak torque and 26* at peak power. I did cut a couple low 2.2x 60’ times, but they were with different AFRs and timings that just didn’t do as well. I could get away with Lambda ~ 0.9 with the old degreeing and not lose power, but I had to pull so much timing with Lambda ~ 0.9 with the cam where it is that I lost power going leaner. So, the gist of the story is by moving the cam and going to an 85mm MAF over the winter I lost less than a mph and picked up 4 tenths. I ran at full weight both times… I didn’t even bother to pull out the base for the car seat this time. I think it would be cool to eventually hit 12s with the baby seat (sans baby) in the car. I’d like to tell you my race weight, but the scales were bouncing around to the tune of +/- 150 lbs. It’s probably 3900ish with me in the car if I had to guess.

It was a banner day for winning races; I technically only lost to a Mercedes running low 12s in the high 120s. I don’t know Mercedes by looks; I thought a C-Class I saw a while back was a slightly customized Mercury Sable until I spotted the badge. The other race that I “won” but really lost was with a 10/11 Camaro SS (LS3/Manual). I had a better reaction time, but neither one of us was going for reaction time (I was 0.5s every time, because I just wanted the slips. He went 0.74!). He ran 13.47 @ 109.1 to my 13.58 @ 105.1. We both cut 2.29ish 60’ times. He didn’t really close the gap until after his last shift.

No one could cut a good 60’ time on street tires. The best 60’ times on pure street tires that I saw all day were from a G8 (2.0x) and a CAI/Livernois Tune MKS AWD Ecoboost (2.01). There might have been others, but I spent more than half of my time in the stands or playing with HP Tuners on my laptop so I didn’t get to talk to everyone (they display reaction times and results, not 60’ times). I really believe that I can cut a better 60’ on the street. I would have lost to several pony cars in the 12s had I lined up against them, but I would have beat most of the pony cars I didn’t beat outright. Just based on times I was seeing from the stands, I also would have beat a C5 Vette, a modded G8, and a whole slew of misc. other cars. Overall, I don’t feel too bad about not running faster. I’m going to try and hit a few other tracks this summer and see if there is any difference in my performance.



I’m still undecided about what my next step is. I could try to play with my cam again (I did advance it 25 degrees at the crank after all). I could just accept that my lifter life is longer now, and start saving for head work and a custom non-DOD cam. I could also spray it finally, although that doesn’t mean I won’t do the cam work too.

nmp0098

I can't wait to see your build finished. I might be moving my cam closer to where you put yours... only time will tell.

DavidGXP

iTrader: (14)

Now were talking.. I can almost live with those times. I'd still like to see more mph with your mods. The 3.29's probably make it pretty hard to launch!

Give it up man, and just scrap the DOD. Life would be so much more simpler.
No point in tearing it back apart to just tear it back apart when the lifters do decide to blow. Those DOD lifters are heavy!

I'd recommend going with a custom cam and DOD delete kit.
Get some LS6 intake and exhaust valves and have them back cut. Leave the ports alone and mill the heads for 10.25 or 10.5cr. You could even sell your heads and step up to the Trickflow 5.3 heads.

Sell that cam

nmp0098

Because I'm both stubborn and cheap, I decided to redegree my cam a 2nd time. I got it done a couple months ago, but weather and family events conspired to keep me from the race track until this last weekend (Milan's final weekend!). The cam is now installed between straight up and 2 degrees advanced, which translates to advancing the cam between 20 and 22 degrees. I'm now shifting around 6850 RPM on a max effort run (I have it shift at 6500 in Drive and I set it up to auto shift in Tap mode at 6850). I managed to get another personal best:



I was running 13.1s at 108 all day, but those two runs show my best ET and MPH. Not to shabby for a car that weighs over 3900 lbs. with me in it riding on street tires. That beats my MPH from when the cam was installed dot to dot (20 degrees of retard) and my ET from the cam was too advanced (about 12 degrees advanced due to a snafu on my part...). This is actually where I thought I would be when I first bought the cam...

The biggest change aside from the cam is that I'm also running Firestone Firehawk Indy 500 Wide Oval 275/40R18 tires. They offer much better launch traction than my Goodyear Eagle F1 all seasons did. I also did some work on traction control, or at least the tables in the ECM that effect the response of the engine to torque reduction requests from the EBCM. That prevented me from losing traction at torque peak.

Overall, the car is running solid at 64k, and I got just over 20mpg on the way home including a stop at McDonalds.

Edit: As a side note, the car seems insensitive to running more than 22* of advance.

supercatxr7

iTrader: (5)

Good job! Slicks should get you some 12.8's.

DavidGXP

iTrader: (14)

20 degrees advanced from stock.... jeeze.
Very nice job, and I'm glad your still around. I really wish it would quit raining so I could make it out to the track and test out my new trans and shift points. I can't have you catch up to me now can I?

Find some spring blockers or do the rear cable mod. It does help. Also, take the weight out of the trunk!

fieroguru

iTrader: (1)

Glad to see the update! So it sounds like your cam is installed +/- 4 degrees from mine now (I targeted installing mine 16 degrees advanced from dot to dot, but think it ended up being close to 18).

From the various hp calculators you should be in the 383-409 flywheel hp range.

I finished my 383/Getrag distraction and am finally back working on the LS4/F40 install with this same camshaft. I am hoping to have it running before for the end of the year so I can contribut my #'s as well. I would love to hit 350-375 whp with the manual transmission and 12lb flywheel... time will tell.

nmp0098

You'll probably really like the cam where you put it with your lighter car and better gearing. I'm really interested to see how you get DOD working with that manual trans and no TCM. It feels like another gear engaging in my car.

The grind has 20 degrees of retard when installed dot to dot. Some of that may be due to a difference in timing gears between the GP and G8. There's a bulletin on Comps website that would account for 13 degrees of that, but I never followed up on that theory. I've actually been looking at air springs too, but not too hard. There's N2O, headwork, tires, 3.69s and roller rockers to add too.

Thanks! I can't wait to see you break the next barrier and hit 10s.

DavidGXP

iTrader: (14)

You will love the 3.69's. The acceleration from 2nd to 3rd is very scary when doing 55mph and flooring it from 4th. You will end up mid way thru 3rd in about 3 seconds. Hold on the steering wheel with two hands when traction is good, or you'll be sorry! Launching in 2nd with tap mode is unreal. First gear is not really needed.

When doing 60mph, I am a spinnig @ 1800-2000RPM (depending on converter slip) using 16-19% throttle. 70mph is 2200rpm locked using 19-22% throttle.

The gearing also helps to slow the car down without using a lot of brake pedal.

1Fast7

Would there be any more of a benefit to use the cam from a G8 GXP?