Finally made it in, just want to get more MPH now
09-20-2009, 08:13 AM
#1
Finally made it in, just want to get more MPH now Two best times 11.67 @ 114.92 1.79 60 ft and 11.70 @ 116.08 1.7660 ft. DA was 897 and 1180
Finally took the old car back to the strip (Lapeer for those in Michigan). First time ever of DR's so I need to learn more about tire pressures and the burnout but that will take more practice. Overall very happy. I need to figure out why I can't get more MPH out of it, I think I need more cam up top. AFR was dead on so it not the tune.
The 1/8 is really good @ 97+ MPH but only gaining 17 or so in the 1/4.
Race weight is 3650 lbs. Leaving low at 1500 RPM's to minimize spin. At this track you get warned for going below 11.5 if you don't have a cage. I really don't want to tear my car you for a cage.
http://www.youtube.com/watch?v=4B3eticldVM
Finally took the old car back to the strip (Lapeer for those in Michigan). First time ever of DR's so I need to learn more about tire pressures and the burnout but that will take more practice. Overall very happy. I need to figure out why I can't get more MPH out of it, I think I need more cam up top. AFR was dead on so it not the tune.
The 1/8 is really good @ 97+ MPH but only gaining 17 or so in the 1/4.
Race weight is 3650 lbs. Leaving low at 1500 RPM's to minimize spin. At this track you get warned for going below 11.5 if you don't have a cage. I really don't want to tear my car you for a cage.
http://www.youtube.com/watch?v=4B3eticldVM
Last edited by 69LT1Bird; 09-20-2009 at 09:45 AM.
09-20-2009, 02:35 PM
#2
I would have to say your converter is slipping way too much on the big end. 97mph at the 1/8th means you are making great power, which most small cam L92 setups do. I have read how some guys experiment with locking the converter above a certain mph to help them gain on the top end. You could be over revving too or something you never know. For reference my car gains 26-27mph from the 1/8th to the 1/4 and I know you make a lot more power, but its not apples to apples because my car is a manual. Still though I would expect a 24-26 mph gain with a good converter.
09-20-2009, 08:53 PM
#4
Were you running 26" tall tires or what size? 5800 rpm would be 120mph if your converter was not slipping at all. 5500 rpm would be 114 mph with 0% converter slippage. So it looks to be slipping 200-300 rpm which I am not sure how much is normal with a stall converter. I know if you locked it up though there should be no slipping. You will have to ask some of the more knowledgable guys on here as I dont know much about autos.
09-21-2009, 01:26 PM
#6
With your gearing I think you sould try a 26" tall tire. At 5800 rpm you should be going 130 mph with a 28" tire. 5100 rpm would be about 114mph so you are actually slipping quit a bit. There is a lot of potential there to go much faster, just need to work out a few things.
09-21-2009, 04:34 PM
#7
I found something on my logs on HP Tuners. At 5500-5600 rpms in second and third gear, the rpm's kind of lay down for a second and then go again. The graph is the same on all of the logs (8 in all) so its not a random thing.
The tune is on, the AFR is at my commanded, timing good, no TCC engagement it is not commanded except in 4th gear. It is making me think more and more about the converter now.
Its almost like it fighting itself at that RPM and then it releases.
The tune is on, the AFR is at my commanded, timing good, no TCC engagement it is not commanded except in 4th gear. It is making me think more and more about the converter now.
Its almost like it fighting itself at that RPM and then it releases.
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10-02-2009, 05:46 AM
#9
I show 89% converter efficiency when I an logging the data, I don't think the converter is the issue. I have a spot at 5500-5600 rpms where the motor stops revving/flatpot.
I would probably get a Coan if I do change the converter.
I developed an oil leak after these runs and found that I have lost compression in 5 and 7, down to 85 PSI, air pressurizing the crank case, the rest are 190-200.
Off come the heads this weekend to survey the damage.
I would probably get a Coan if I do change the converter.
I developed an oil leak after these runs and found that I have lost compression in 5 and 7, down to 85 PSI, air pressurizing the crank case, the rest are 190-200.
Off come the heads this weekend to survey the damage.
10-14-2009, 03:00 PM
#10
Just found the new numbers in your sig in another thread. Congrats! Here's hoping I'm around there when I (finally) finish the Nova. Let's see, same basic setup save LS3 intake, LG g6x3 cam, American Racing headers, 4L80e, and about 300# less weight. And I'm sure the tune will be different. Just praying I don't grenade the thing when I fire her up.
10-14-2009, 07:35 PM
#11
Tore the car down and I broke the ring lands between the compression rings and between the 2nd ring and oil ring on 5 and 7.
New pistons and a different cam are going in, hopefully I can get it all done before the snow flies, it should be fun on all 8 cylinders.
New pistons and a different cam are going in, hopefully I can get it all done before the snow flies, it should be fun on all 8 cylinders.
