View Full Version : More mods, better DA, but slower, confused...
08-22-2009, 07:02 PM
Alright guys I am pretty confused as of lately and would like an outside view on the situtation. Here are my runs and info.
Density Altitude: 3861
3700LB raceweight 12.7 AFR 6300-6500 RPM Shift
8/7/09 I added a custom FTRA type intake that I built and an 85mm throttle body.
Density Altitude: 2651
3800LB raceweight 12.65 AFR 6100-6400 RPM Shift
8/22/09 Added a shift light for more consistant shifts
Density Altitude: 3060
3700 raceweight 12.6 AFR 6500 RPM Shift and a little race gas to avoid detonation.
Ok guys so what the hell is going on, I always use hptuners with a wideband and I monitor everything making sure everything is in line. I have logs from all my runs. Could my ram air setup I build be my loss of power, I thought everyone gained from this, but I do have an SS that had the bottom tray cut open and sealed to the hood. Should I do a compression test, could my plugs be shot (TR 55 w/ 10,000 miles), fuel filter?. What the hell could be going on? I would not have thought with better weather and my new mods I would be slower. My engine has 117k on it now and maybe its just getting old. I am tempted to yank the ram air setup out and see what happens. I know I need to throw some slicks on it but I am going to be putting a 9" under it shortly. Thanks for your input.
Here is a picture of it
08-23-2009, 06:56 PM
You guys must be as clueless as me. Maybe I should retorque all my rocker arms, I dont think they are loose but I'm not sure what to check.
TORCHD 02 TA
08-24-2009, 01:06 AM
hmm i dunno. I have the same custom home made FTRA too :)
I thought that you and i were close when time slips where compared. And i thought you had a bigger cam and head work?
That is crazy that you are running slower. You need to lose some weight on the car. I weighed mine the other day FULL INTERIOR, FULL TANK OF GAS and i came in at 3640. But when i go to race i added up what i take out and my race weight will be 3465...
Dunno what is wrong with your set up :(
Maybe you are running out of fuel? What injectors are you running? And your 60s are not helping your times either? I forgot what you had for a rear and gear.. Plus you on DRs? I would change the TR55s and get a colder TR6 plug.
I jsut got me some alloy 16x8s and some M/T DRs.. 11s here i come
08-24-2009, 02:19 AM
I have unported 243 heads with a custom 224 cam and I am running the stock 10 bolt with 3.42s. My tires are Nexen 3000's 275/40/17 on SLP ZR1 wheels. I am running 30lb svo injectors and my duty cycle is plenty safe. I am going to install new spark plugs and a fuel filter to see if that helps. I will also do a compression / leak down test. My shifts have gotten a little slower lately I think I need to bleed the clutch because it's being a bitch to bang 2nd without grinding.
08-24-2009, 10:24 AM
try giving it more fuel...
09-02-2009, 07:55 AM
i would put your AFR to around 12.9-13.0 i have bolt ons and a cam and im going low 12s with it set that way. when i richen it up more the car goes slower.. give it a try...
Mikey 97Z M6
09-02-2009, 11:31 AM
I'd start looking at the engine. Do a compression check. How old are the valvesprings? Maybe pull a spring out and have it checked for proper pressure.
A 3mph drop in trap speed under better conditions,,,,, something else is going on IMO.
09-02-2009, 11:33 AM
A few things to consider:
-he 60 foots aren't consistent, and that accounts for some of the up and down time.
-DA alone doesn't give you a true "factor" on why the car runs faster or slower, it is only a gauge of it. For example, you can have a 2000 DA with mild and a bunch of humidity, versus the same DA with warmer air but no humidity and the car should run better in the 2nd set of conditions. I log all the weather conditions just for this reason.
-I'd guess the 6500 rpm is too high of a shift point. Checking the run versus your other two, the MPH is down (even against the 3800 DA pass with a similar 60 foot).
Just my $.02
09-02-2009, 01:06 PM
How much race gas to how much pump gas? What type of race gas? The higher the octane rating the less volatile the fuel will be. You should run the lowest octane fuel that you can get away with to avoid KR and make optimum power. If you are running a higher octane fuel than necessary you are reducing power output. I would also recommend you move to the TR6 plugs.
09-02-2009, 03:19 PM
Ok well I did a compression test and everything look good within 5-10 psi on each cylinder. I used 3 different gauges and my cranking compression ranged from 210-230 psi depending on the gauge. I installed some TR-6 plugs and this has helped with knock retard. I swapped out the fuel filter and also bled the clutch. I drove to the track and I got 1 shitty run in and it ******* rained. 3 weeks in a row now I have only made 4 total passes, because of weather or some douche bag oiling down the track. Either way I am still not trapping 115mph like I was and I think its this stupd ram air everyone thinks actually does something. I have ran the AFR from 12.4 to 13.1 and it makes no difference on my car.
This friday if it does not rain I am going to run a few passes with the airbox completely sealed. Than I am going to remove the front seal and see if that helps. After that I will remove the thing completely. I am down in the 1/8th mile but my 1/8 to 1/4 mph gain is the same as it has always been. I gain 25.5 to 26 mph from the 1/8th to the 1/4. I believe with the ram air there is not enough air to pull in at low speeds. I will let you guys know.
09-02-2009, 03:45 PM
From what I'm reading it's not an apples to apples comparison.
you went 12.8 at 115 at 3700 lbs. 3861 DA
then you went 12.8 at 3800 lbs with a new 85mm tb and the ram air. 2651 DA
then you go 13.0 at 112 now back to 3700 lbs but with race gas 3060DA
You have to tune for the tb if it's larger than the one you replaced.
Race gas will slow you down if you're not tuned for it.
09-02-2009, 03:57 PM
Maybe not a 100% comparison but enough to know I should not be going slowerr than I used to. I took most of the variables out and the ram air is the last variable I have not tried. Of course I retuned for the throttle body, hptuners hardly leaves the car and I drive the thing everyday. I could post all my scans of me running the car if you guys want. Valve springs should be good they are PAC 1518 springs with only about 7,000 miles on them.
TORCHD 02 TA
09-02-2009, 06:46 PM
Not to hijack.. But i told the OP i let him know when i was going to the track again..
I went last night, got my best time.. 11.88 @ 119 :)
If you want to check it out, i made 2 threads. One in the 12 sec forum and one in the 11 sec forum.. The thread in the 12 sec forum has more info there
09-03-2009, 04:56 AM
Awesome man a friend of mine is going to let me use his 255/50/16 MT ET streets this friday. If it doesn't rain I will let you know how it goes. I really hope I dont blow my 10 bolt so I will launch it easy.
09-03-2009, 03:34 PM
I just had a brain fart. If you are using that 85mm TB with an LS6 intake you may have an edge where the TB transitions to the intake opening. This may be causing turbulence and reducing the velocity of the incoming air. Can you take a picture of the inside of the TB on the intake with it at WOT?
I saw where you posted the MAP reading question in the other thread. Optimally you should see a reading as close to 100 as you can get at WOT. Anything lower and this is indicating that your engine is pulling a vacuum against an intake restriction. What does your MAP read with the scanner when the engine is not running?
09-03-2009, 04:01 PM
Standard barometric pressure is usually around 94 kpa and I usually fall off to 90-91 kpa around 6000 rpm. I ported the end of my LS6 intake to match the 85mm throttle body. There is no longer a rubber o-ring as I opened it all the way up. Search "85mm LS6" you will see pics of what other people have done. Map readings were also 90-91 with the LS1 throttle body.
09-03-2009, 04:27 PM
You should be good if you matched the ID. I have actually seen my MAP as high as 101 on the scanner at WOT and generally see a reading of 99-100 with the engine off. It's probably the elevation difference b/c my local track sits 12 feet above sea level.
09-04-2009, 06:32 PM
What are you IATs?
You mentioned knock retard in one post. Does that occur in all your runs?
What's your actual timing in all your runs?
09-05-2009, 02:47 PM
IAT sensor is located just in front of the washer fluid reservoir, and they are usually a few degrees above ambient. 70-100 degrees depending on the day, and not every run I get knock retard, only if I try to run more than 20 degrees of timing @ 4000 rpm. I have played with my timing curves quite a bit but best results have been achieved with this curve.
09-08-2009, 02:51 PM
When you made the ram air did you seal off your airbox in the stock inlet location? It sounds like you may have and that ram air looks pretty small at the top. I think just take it out and see I don't think tb is really hurting you in this setup.
09-12-2009, 03:51 AM
Alright well I got to make one pass on MT ET streets and those are some scary tires! I was at the track for 4 hours and only got 2 passes in pretty bad if you ask me. Anyways here are the details. I launched at 4000 rpm and they spun pretty bad but I stayed in it. I went across the traps on the rev limiter in 3rd gear, thought I could make it with the taller tire! I was also granny shifting because I was afraid to blow the 10 bolt. Also how the hell did I gain 27.5 mph from the 1/8th to the 1/4? This makes no sense and this is by far my slowest 1/8th mph. The track is really starting to frustrate me, I don't think its worth it to make 2 passes in 4 hours.
255/50/16 MT ET STreets @ 20 psi
3700LB raceweight 12.7-13 AFR 6300-6500 RPM Shift
9/11/09 I removed the seals on the front of the ram air, was not able to make another pass and remove it, very frustrating!
Density Altitude: 3048
Oh ya almost forgot on the way home from the track I ran a 2010 Camaro SS from 60-110. I put 2-3 lengths on him, I was surprised he stayed at my door through 2nd gear.
One last thing, my brakes were not working worth a shit at the end of the track what is up with that? They were pulssating and I had to take the long way around the track because I could not slow down. My friend said because I had 17's up front and 16's in the back, is this true?