1973 RS Camaro LSX Swap
Thanks brother! That's quite a compliment. That was 4000RPM off the brake. It actually slowed my 60' just slightly from my previous 3800 launch, so I ultimaltey settled in back down at 3800 after trying a few other RPMs. But now looking back, I'm not sure the slight reduction in 60' had so much to do with the launch RPM as it did with other factors. I mean, it only slowed it by a couple hundreths. I think I need go back some time with fresh tires and re-evaluate where the car likes to leave. My general conclusion so far was that higher was better, but 4000 seemed to be the falling off point on the high side. There is just soooo much to work out with a brand new combo that I think I was quick to settle in at 3800 so I could move on to something else.
Thanks man. That's cool that you've still got your first car. I got rid of my first four cars, but I've still got my first brand new car.....my 99TA. No real plans of ever parting with it!
I just read through your thread today, really enjoyed it. It addressed several questions I had about LY6 carb setups. I had a few questions if I may:
1) Your overflow is mounted up pretty high. Does your setup suck the coolant back into the radiator after driving or making a pass?
2) So the LY6 water pump inlet/outlets are 1.5" diameter, great to know. No question really.
3) So your converter only gets up to 4000 on the transbrake, so it's not really a 5000-5200 as you had already hoped? I had a 4800 8" in my 2000 Z/28 and it did go up to 4800 on the brake and it was 60 fti'ing 1.48 on hp and 1.38 on 150 shot. Thought about pulling it and getting it loosened up, I'm presuming you also think you'd drop your 60 down in the 1.5's at least?
4) I'm interested in the wiring aspects for the box, any advice for the newb as to how you would run the important stuff?
5) What rpm are you shifting at, and are you running 28" tall Hoosier QTP's?
11 years after it's creation, this forum is truly awesome for research purposes.
-John
1) Your overflow is mounted up pretty high. Does your setup suck the coolant back into the radiator after driving or making a pass?
2) So the LY6 water pump inlet/outlets are 1.5" diameter, great to know. No question really.
3) So your converter only gets up to 4000 on the transbrake, so it's not really a 5000-5200 as you had already hoped? I had a 4800 8" in my 2000 Z/28 and it did go up to 4800 on the brake and it was 60 fti'ing 1.48 on hp and 1.38 on 150 shot. Thought about pulling it and getting it loosened up, I'm presuming you also think you'd drop your 60 down in the 1.5's at least?
4) I'm interested in the wiring aspects for the box, any advice for the newb as to how you would run the important stuff?
5) What rpm are you shifting at, and are you running 28" tall Hoosier QTP's?
11 years after it's creation, this forum is truly awesome for research purposes.
-John
1) Your overflow is mounted up pretty high. Does your setup suck the coolant back into the radiator after driving or making a pass?
Yeah, the top of the overflow tank is just about even with the top of the radiator. But, there's an internal siphon tube that extends to the bottom of the overflow tank. So far it seems to recirculate just fine back into the radiator, and I'm sure the siphon tube is the key.
2) So the LY6 water pump inlet/outlets are 1.5" diameter, great to know. No question really.
Actually, that's probably misleading on my part, so I'm glad you asked. I'm running all 4th Gen LS1 F-body accessories, so it's and F-bod water pump. The LY6 water pump was spaced out much further to clear the cam phaser (which I eliminated) under the front cover and had different inlet/outlet positions for the trucks. I'm not certain if they were also 1.5 or not. Sorry....no help there.
3) So your converter only gets up to 4000 on the transbrake, so it's not really a 5000-5200 as you had already hoped? I had a 4800 8" in my 2000 Z/28 and it did go up to 4800 on the brake and it was 60 fti'ing 1.48 on hp and 1.38 on 150 shot. Thought about pulling it and getting it loosened up, I'm presuming you also think you'd drop your 60 down in the 1.5's at least?
No, 4000 is just the highest I've tried setting the 2-step at the track. The converter will actually go to 4800 on the brake with the 2-step turned completely off. It's a custom PTC that I bought used so it wasn't necessarily spec'd to my particular combo. But it was sold as a 5000-5200 for the near full weight, cam only, LS1 F-body that it was spec'd for. Even still, I suspect it would probably go all the way 5000-5200 in my combo if I were closer to sea level. Up here in high DA country I'm probably down enough on power to take close to take a couple hundred RPM out of it.
If I'm being completely honest, I was really hoping for mid to high 1.5s out of this combo, and maybe I'll still get there with this converter....just at a slighly higher power level. I'm wondering if there's anything left by launching off the top of the converter if the track will hold? It's something I haven't tried yet. Once I start spraying, I don't know if this thing will be too loose or not? If so, I'll probably just buy a whole other converter.
4) I'm interested in the wiring aspects for the box, any advice for the newb as to how you would run the important stuff?
The 6LS box's wire up pretty easily compared to other's like the old 6AL's and such (not that they're that hard either). But one important thing to note is that there is only one single 12V power wire to the 6LS box and not a separate 12V constant and 12V keyed input. So you want to be sure that your 12V to the box is clean/solid, yet keyed if you expect the ignition switch to kill the car. In my case, I wanted to be sure that the master disconnect would kill the ignition, so I ran the 12V source directly from the battery and through the secondary posts on my disconnect switch before hitting a fuse and going to the box. I also have the feed wire running through a second kill switch on my dash. Thats how I kill the car as the ignition key is completely out of the loop.
Ground is also very important to these boxes not cutting out under high RPM. Mine is grounded to the back of one of my cylinder heads. I felt good about doing this because I ran a full sized ground cable all the way from the battery to the engine block. From there I have ground cables running from the block to the subframe and to the body.
All of your other wires for basic operation are simple plug and play (cam sensor and crank sensor). The MAP sensor is completely optional if you want to set up a vacuum-based timing curve. I have mine plugged in for reference but I have the MAP timing table zero'd out. That just scares me at the track to have a potential for additional timing to be accidentally added. From there you have the 2-step and timing retard functions left to wire if desired. They are both activated by a 12V source. So, I simply have my 2-step tied into the 12V feed for my trans brake. Basically, when the brake sees 12V's the 2-step is also activated; when I release the brake the 2-step is inactivated. Since I don't have an N20 kit on the car yet I haven't wired up the timing retard function yet. However, when I do.....I'm pretty sure I'll wire the retard wire to the 12V arm switch rather than to the 12V feed to the noids. I haven't thought this completely though, but my initial thought is that I can't see a time when I'd have the system armed and still require full timing. I have enough advance in at idle that I can pull from it and still be OK. The other reason is that I'll likely also be running a progressive and don't want the retard function wired up in that mess. The other thing I'll need to do is wire in a relay to disarm the kit while I'm on the 2-step. I have my 99 TA wired this way through a clutch switch so the 2-step deactivates and the N20 activates when I dump the clutch.
5) What rpm are you shifting at, and are you running 28" tall Hoosier QTP's?
Currently my shift light is at 6900 and the limiter is at 7K. These are obviously too close together as I sometimes tickle the rev limiter on the 1-2 shift. I need to turn the limiter up to about 7500. I also want to experiment with some higher shift points in the future and see if it likes it. I suspect it would with the L92 heads and single plain combo, but only testing will tell. The cam is ground on HUC lobes and I'm running PRC Extremem Duals, so valve control shouldn't get out of control given a few more RPM. Oh yeah.....28" tall QTPs is correct. They are 28X11.50's to be exact.
11 years after it's creation, this forum is truly awesome for research purposes.
-John
Yeah, the top of the overflow tank is just about even with the top of the radiator. But, there's an internal siphon tube that extends to the bottom of the overflow tank. So far it seems to recirculate just fine back into the radiator, and I'm sure the siphon tube is the key.
2) So the LY6 water pump inlet/outlets are 1.5" diameter, great to know. No question really.
Actually, that's probably misleading on my part, so I'm glad you asked. I'm running all 4th Gen LS1 F-body accessories, so it's and F-bod water pump. The LY6 water pump was spaced out much further to clear the cam phaser (which I eliminated) under the front cover and had different inlet/outlet positions for the trucks. I'm not certain if they were also 1.5 or not. Sorry....no help there.
3) So your converter only gets up to 4000 on the transbrake, so it's not really a 5000-5200 as you had already hoped? I had a 4800 8" in my 2000 Z/28 and it did go up to 4800 on the brake and it was 60 fti'ing 1.48 on hp and 1.38 on 150 shot. Thought about pulling it and getting it loosened up, I'm presuming you also think you'd drop your 60 down in the 1.5's at least?
No, 4000 is just the highest I've tried setting the 2-step at the track. The converter will actually go to 4800 on the brake with the 2-step turned completely off. It's a custom PTC that I bought used so it wasn't necessarily spec'd to my particular combo. But it was sold as a 5000-5200 for the near full weight, cam only, LS1 F-body that it was spec'd for. Even still, I suspect it would probably go all the way 5000-5200 in my combo if I were closer to sea level. Up here in high DA country I'm probably down enough on power to take close to take a couple hundred RPM out of it.
If I'm being completely honest, I was really hoping for mid to high 1.5s out of this combo, and maybe I'll still get there with this converter....just at a slighly higher power level. I'm wondering if there's anything left by launching off the top of the converter if the track will hold? It's something I haven't tried yet. Once I start spraying, I don't know if this thing will be too loose or not? If so, I'll probably just buy a whole other converter.
4) I'm interested in the wiring aspects for the box, any advice for the newb as to how you would run the important stuff?
The 6LS box's wire up pretty easily compared to other's like the old 6AL's and such (not that they're that hard either). But one important thing to note is that there is only one single 12V power wire to the 6LS box and not a separate 12V constant and 12V keyed input. So you want to be sure that your 12V to the box is clean/solid, yet keyed if you expect the ignition switch to kill the car. In my case, I wanted to be sure that the master disconnect would kill the ignition, so I ran the 12V source directly from the battery and through the secondary posts on my disconnect switch before hitting a fuse and going to the box. I also have the feed wire running through a second kill switch on my dash. Thats how I kill the car as the ignition key is completely out of the loop.
Ground is also very important to these boxes not cutting out under high RPM. Mine is grounded to the back of one of my cylinder heads. I felt good about doing this because I ran a full sized ground cable all the way from the battery to the engine block. From there I have ground cables running from the block to the subframe and to the body.
All of your other wires for basic operation are simple plug and play (cam sensor and crank sensor). The MAP sensor is completely optional if you want to set up a vacuum-based timing curve. I have mine plugged in for reference but I have the MAP timing table zero'd out. That just scares me at the track to have a potential for additional timing to be accidentally added. From there you have the 2-step and timing retard functions left to wire if desired. They are both activated by a 12V source. So, I simply have my 2-step tied into the 12V feed for my trans brake. Basically, when the brake sees 12V's the 2-step is also activated; when I release the brake the 2-step is inactivated. Since I don't have an N20 kit on the car yet I haven't wired up the timing retard function yet. However, when I do.....I'm pretty sure I'll wire the retard wire to the 12V arm switch rather than to the 12V feed to the noids. I haven't thought this completely though, but my initial thought is that I can't see a time when I'd have the system armed and still require full timing. I have enough advance in at idle that I can pull from it and still be OK. The other reason is that I'll likely also be running a progressive and don't want the retard function wired up in that mess. The other thing I'll need to do is wire in a relay to disarm the kit while I'm on the 2-step. I have my 99 TA wired this way through a clutch switch so the 2-step deactivates and the N20 activates when I dump the clutch.
5) What rpm are you shifting at, and are you running 28" tall Hoosier QTP's?
Currently my shift light is at 6900 and the limiter is at 7K. These are obviously too close together as I sometimes tickle the rev limiter on the 1-2 shift. I need to turn the limiter up to about 7500. I also want to experiment with some higher shift points in the future and see if it likes it. I suspect it would with the L92 heads and single plain combo, but only testing will tell. The cam is ground on HUC lobes and I'm running PRC Extremem Duals, so valve control shouldn't get out of control given a few more RPM. Oh yeah.....28" tall QTPs is correct. They are 28X11.50's to be exact.
11 years after it's creation, this forum is truly awesome for research purposes.
-John
Last edited by GC99TA; Mar 9, 2012 at 10:13 AM.
Great info thanks!
So the two-step only goes up to 4000, or can you set it higher? I would set it higher if the track will hold it. Your 60 ft times sound about right for a 4000 launch, 4.10's, 28's and 3400 raceweight.
I'll be curious to see if higher shift points make a difference with that cam grind. I shifted my 240/244 348 setup at 7k supposedly would have liked more but the cam was pretty darn big... .went 123 @ 3350 on hp at like 1000 da.
Are you running one of the pre-set timing curves with the MSD?
So the two-step only goes up to 4000, or can you set it higher? I would set it higher if the track will hold it. Your 60 ft times sound about right for a 4000 launch, 4.10's, 28's and 3400 raceweight.
I'll be curious to see if higher shift points make a difference with that cam grind. I shifted my 240/244 348 setup at 7k supposedly would have liked more but the cam was pretty darn big... .went 123 @ 3350 on hp at like 1000 da.
Are you running one of the pre-set timing curves with the MSD?
All of my (limited) experience drag racing over the last 10-12 years has been with a stick shift car, so I'm still on a learning curve with launching high stall autos. I don't know if this sounds right or not, but my auto buds have told me that launching off the top of the converter could cause the car to bog, much like a clutch dump since there isn't any "give" left. They said they've had best luck launching somewhere several hundred RPM below the maximum stall speed to let the converter flash a little higher on launch. But I don't know....I'm pretty curious too. I would love it if it would 60' better with just a higher launch cause I think the suspension is up to it. What are you thinking.....around 4500? I think the converter would tolerate 4700-4800 maximum......with 4800 risking not reaching the 2-step before the converter tightens way up.
No, I'm running my own curve. The MSD curves are pretty weak if you don't run some sort of custom MAP curve to supplement them. And even then.......not so great. That's the beauty of the MSD box vs the Edelbrock...at least you have complete control over your timing and don't have to use the preset pills.
No, both the 2-step and high end rev limiter can both be set to limits beyond reality....LOL. I think their max settings are up over 9K somewhere, if not 10K. So that is not a limiting factor.....at least not in anything I'll ever put together....LOL.
All of my (limited) experience drag racing over the last 10-12 years has been with a stick shift car, so I'm still on a learning curve with launching high stall autos. I don't know if this sounds right or not, but my auto buds have told me that launching off the top of the converter could cause the car to bog, much like a clutch dump since there isn't any "give" left. They said they've had best luck launching somewhere several hundred RPM below the maximum stall speed to let the converter flash a little higher on launch. But I don't know....I'm pretty curious too. I would love it if it would 60' better with just a higher launch cause I think the suspension is up to it. What are you thinking.....around 4500? I think the converter would tolerate 4700-4800 maximum......with 4800 risking not reaching the 2-step before the converter tightens way up.
All of my (limited) experience drag racing over the last 10-12 years has been with a stick shift car, so I'm still on a learning curve with launching high stall autos. I don't know if this sounds right or not, but my auto buds have told me that launching off the top of the converter could cause the car to bog, much like a clutch dump since there isn't any "give" left. They said they've had best luck launching somewhere several hundred RPM below the maximum stall speed to let the converter flash a little higher on launch. But I don't know....I'm pretty curious too. I would love it if it would 60' better with just a higher launch cause I think the suspension is up to it. What are you thinking.....around 4500? I think the converter would tolerate 4700-4800 maximum......with 4800 risking not reaching the 2-step before the converter tightens way up.
Yeah, it's one of those things I just need to try. The cam isn't very large, so it may not need/like it. But then again, these L92s flow a lot of air on the intake side for a given amount of lift and duration, just due to their intake valve size. So the 231 intake lobe may be a bit deceiving? 123 is great MPH for a 348 at that weight! I'm assuming that was an auto car? My 99 TA (stock bottom 346; 3480lb race weigh) went a best of 123 in 1000ft air also, but it's an M6....so not nearly as impressive. The ET on that pass was only 11.37. Cam in it is a 228/230-112 with AFR 205s. Shifts were also at 6900-7000.
I know my combo was going thru the lights below 6500, and it would have like 4.30 gears. Rodney smokino1ta used to run 4.57's I think with his MN6 cam only T-rex cam setup in the white TA.
PSJ: I'm definitely a fan of trying to get some flash out of the converter but I would try more rpm. I personally would raise the two-step up from 4000, I think that's too low. And I would try 4400, and see what it does, and I would keep the same shift points so that you can compare the data to your other passes. I'd probably try 2-3 hits like that. I would also (this is just me) try 4600-4800 to see what it does. Worst case it wheelies or you spin.
Yeah I would be curious to see what happens if it picks up at all. I've never really seen anyone post results from different shift points. I've seen enough stuff out there and have enough personal experience that I can generally tell sometimes if someone is shifting too low.
I know my combo was going thru the lights below 6500, and it would have like 4.30 gears. Rodney smokino1ta used to run 4.57's I think with his MN6 cam only T-rex cam setup in the white TA.
Yeah I would be curious to see what happens if it picks up at all. I've never really seen anyone post results from different shift points. I've seen enough stuff out there and have enough personal experience that I can generally tell sometimes if someone is shifting too low.
I know my combo was going thru the lights below 6500, and it would have like 4.30 gears. Rodney smokino1ta used to run 4.57's I think with his MN6 cam only T-rex cam setup in the white TA.
If the track holds, I may be able to set some new personal bests with the car just based on the air quality alone! I wouldn't need to do much to prep the car; just need to put my main jetting back to where it's been. I've been messing with the wideband lately and had the mains jetted down to bring the cruise AF mixture into the 14's but didn't have the chance yet to open up the PVCRs to compensate. The WOT AF with the old jetting was pretty good around 12.8 so I'll put it back to where it was for the track for consistency sake. I'll also leave my shift points alone but probalby bump the rev limiter up a few hundred so I stay out of it on the 1-2 shift. If the crowd is light, I'll try a hit as is and then go from there. But if it looks like my runs will be limited, I may go straight for the gusto. I don't like making comparisons between different days when I don't have to, but I have a pretty good baseline for what it does as is because I've been correcting all of my times to sea level for consistency checks. But like mentioned, I would prefer to compare the changes all on one day for sure. Now I just have to check with Mamma to see if a track trip is in the weekly budget.........
Thanks Tony. Hopefully she holds together and I have some new times to post tomorrow night. Weather still looks good but I'm not sure how much temperatute will be in the track. Time will tell I guess. Hourly forecast shows temps around 55 when I should be making my first passes so its possible the DA May be very near actual track elevation of 3075.
Well, I had a great weather day to be at the track today and the car was deadly consistant. In fact, it was so consistant that I couldn't change the 60' times no matter what I did. The worst DA I ran in today was better than the best DA I had run in before, so that was a nice change. I had the chance to try a lot of things today and although I didn't set any new personal best ETs or MPH, I did set some new bests ETs through the full exhaust. Here's how the day played out:
The first pass was my baseline run so I ran the car exactly the way I've been running it (same launch RPM and shift points) up until now. Along with the actual values, I'll also list the corrected slips for comparison sake only. I like to do this to check for consistency between runs on a single day and between runs made on previous dates:
First Pass
DA: 3235ft
Launch: 3800RPM
60’: 1.67
1/8: 7.37
MPH: 94.55
1/4: 11.56
MPH: 116.99
This pass corrects to 11.11@121.83 at a DA of 0ft
Next I wanted to try a higher launch RPM off the 2-step, so I went straight for it and set it at 4400 RPM. To my suprise, this resulted in an identical 60' time and only slightly better ET and MPH, which can probably be attributed to there now being a little more temperature in the transmission.
Second Pass
DA: 3235ft
Launch: 4400RPM
60’: 1.67
1/8: 7.35
MPH: 94.47
1/4: 11.54
MPH: 117.40
This pass corrects to 11.09@122.25 at a DA of 0ft
Since the higher launch RPM had no effect, I set the 2-step back down to my proven leave RPM of 3800 and decided to look for 60' elsewhere. I have been running my Caltrac bars in the upper holes as I believe this to be the best position for my car to hit the tires hardest. I've got a buddy that's been bugging me to try the lower holes to see if it would pick up in the 60', so I tried that next. And guess what......no change.
Third Pass
DA: 3451ft
Launch: 3800RPM
60’: 1.67
1/8: 7.37
MPH: 94.22
1/4: 11.57
MPH: 116.45
This pass corrects to 11.08@121.62 at a DA of 0ft
At this point I determined that my car probably isn't going to 60' too much better until I make more power. The overall chassis and suspension seem to work well and it doesn't seem like power is sufficent enough at this point for it to become responsive to suspension changes just yet. I left the bars in the lower hole for now, but may move them back up to the top until it becomes a problem later on.
So I decided to move on to testing some different shift points to see what affect I could have there. First up was trying 7200 shifts as opposed to my normal 7000ish shifts.
Fourth Pass
DA: 3451ft
Launch: 3800RPM
60’: 1.68
1/8: 7.40
MPH: 94.53
1/4: 11.59
MPH: 116.99
This pass corrects to 11.10@122.18 at a DA of 0ft
As you can see, the car was kind of indifferent to being shifted this high. It really didn't gain or lose much. Maybe just .5 mph in the 1/4. So probably not worth the abuse of the extra couple hundred RPM.
Next I decided to try short shifting it to see if maybe 7000 was excessive too. So I dropped my shift RPM down to 6800.
Fifth Pass
DA: 3530ft
Launch: 3800RPM
60’: 1.65
1/8: 7.37
MPH: 93.32
1/4: 11.60
MPH: 115.74
This pass corrects to 11.10@121.00 at a DA of 0ft
You can see that, despite being the best 60' of the day, this was still the worst ET and MPH of the day to this point. Granted, the DA had gone up again since the 7200 pass, but the 1 MPH loss even shows up in the corrected MPH. Corrected ET was mostly unchanged.
I was pretty satisfied with my launch RPM and shift points by now. So the last thing I was curious about was running with the air filter. I have a 3 inch K&N element but it's on a drop base set up that puts the lid pretty close to the carburetor air horn. Shift point for this pass was moved back to 7000. Here's the result.
Sixth Pass
DA: 3667ft
Launch: 3800RPM
60’: 1.68
1/8: 7.43
MPH: 93.55
1/4: 11.66
MPH: 115.43
This pass corrects to 11.13@120.90 at a DA of 0ft
As you can see, ET and MPH dropped again, with the MPH being the most significant. Again the DA had gone up, but the corrected time shows close to a full MPH loss over ealier corrected times.
So all in all it was an interesting day. Everything came home in one piece and I was back home and unloaded by 3pm. Based on what I've learned about this car so far, I think I could have gotten some 11.4X's out of it in today's weather if I had dropped the exhaust. I guess thats one more track outing in the books for me.
The first pass was my baseline run so I ran the car exactly the way I've been running it (same launch RPM and shift points) up until now. Along with the actual values, I'll also list the corrected slips for comparison sake only. I like to do this to check for consistency between runs on a single day and between runs made on previous dates:
First Pass
DA: 3235ft
Launch: 3800RPM
60’: 1.67
1/8: 7.37
MPH: 94.55
1/4: 11.56
MPH: 116.99
This pass corrects to 11.11@121.83 at a DA of 0ft
Next I wanted to try a higher launch RPM off the 2-step, so I went straight for it and set it at 4400 RPM. To my suprise, this resulted in an identical 60' time and only slightly better ET and MPH, which can probably be attributed to there now being a little more temperature in the transmission.
Second Pass
DA: 3235ft
Launch: 4400RPM
60’: 1.67
1/8: 7.35
MPH: 94.47
1/4: 11.54
MPH: 117.40
This pass corrects to 11.09@122.25 at a DA of 0ft
Since the higher launch RPM had no effect, I set the 2-step back down to my proven leave RPM of 3800 and decided to look for 60' elsewhere. I have been running my Caltrac bars in the upper holes as I believe this to be the best position for my car to hit the tires hardest. I've got a buddy that's been bugging me to try the lower holes to see if it would pick up in the 60', so I tried that next. And guess what......no change.
Third Pass
DA: 3451ft
Launch: 3800RPM
60’: 1.67
1/8: 7.37
MPH: 94.22
1/4: 11.57
MPH: 116.45
This pass corrects to 11.08@121.62 at a DA of 0ft
At this point I determined that my car probably isn't going to 60' too much better until I make more power. The overall chassis and suspension seem to work well and it doesn't seem like power is sufficent enough at this point for it to become responsive to suspension changes just yet. I left the bars in the lower hole for now, but may move them back up to the top until it becomes a problem later on.
So I decided to move on to testing some different shift points to see what affect I could have there. First up was trying 7200 shifts as opposed to my normal 7000ish shifts.
Fourth Pass
DA: 3451ft
Launch: 3800RPM
60’: 1.68
1/8: 7.40
MPH: 94.53
1/4: 11.59
MPH: 116.99
This pass corrects to 11.10@122.18 at a DA of 0ft
As you can see, the car was kind of indifferent to being shifted this high. It really didn't gain or lose much. Maybe just .5 mph in the 1/4. So probably not worth the abuse of the extra couple hundred RPM.
Next I decided to try short shifting it to see if maybe 7000 was excessive too. So I dropped my shift RPM down to 6800.
Fifth Pass
DA: 3530ft
Launch: 3800RPM
60’: 1.65
1/8: 7.37
MPH: 93.32
1/4: 11.60
MPH: 115.74
This pass corrects to 11.10@121.00 at a DA of 0ft
You can see that, despite being the best 60' of the day, this was still the worst ET and MPH of the day to this point. Granted, the DA had gone up again since the 7200 pass, but the 1 MPH loss even shows up in the corrected MPH. Corrected ET was mostly unchanged.
I was pretty satisfied with my launch RPM and shift points by now. So the last thing I was curious about was running with the air filter. I have a 3 inch K&N element but it's on a drop base set up that puts the lid pretty close to the carburetor air horn. Shift point for this pass was moved back to 7000. Here's the result.
Sixth Pass
DA: 3667ft
Launch: 3800RPM
60’: 1.68
1/8: 7.43
MPH: 93.55
1/4: 11.66
MPH: 115.43
This pass corrects to 11.13@120.90 at a DA of 0ft
As you can see, ET and MPH dropped again, with the MPH being the most significant. Again the DA had gone up, but the corrected time shows close to a full MPH loss over ealier corrected times.
So all in all it was an interesting day. Everything came home in one piece and I was back home and unloaded by 3pm. Based on what I've learned about this car so far, I think I could have gotten some 11.4X's out of it in today's weather if I had dropped the exhaust. I guess thats one more track outing in the books for me.
... My favorite kinda posts, ones where someone tries a bunch of stuff and then shares it on the web. Cool stuff.
I was thinking this morning that pulling 100 lbs out of the car would help quite a bit.
Thanks for sharing the shift points, very interesting info.
I was thinking this morning that pulling 100 lbs out of the car would help quite a bit.
Thanks for sharing the shift points, very interesting info.
Between testing two different cams, testing with and without exhaust, testing an HVH spacer, and then the testing I did today, I've learned quite a bit about what seems to work well with this car. Also I have been correcting all the slips to eliminate weather as a variable. But all my info is spread out through this thread and another smaller one I have in the carb section.
I was thinking about consolidating it all into a new thread in the Drag Racing Results section where I can continue to add to it......perhaps in a single post. But since it's already in here, I don't know if I should duplicate the info for a wider audiance?
I here ya on the 100lbs thing. When I pulled the exhaust off the car for the last trip to the track, the total weight reduction was 70lbs. The average corrected gains were .11 sec and 1.77MPH. But this makes me wonder how much of this gain was from reduced restriction and how much was from the weight loss. It would have been interesting to add the 70lbs back into the car as ballast and measure the results. Either way, my current results tell me that both the weight and free flow probably affected the MPH but the only one factor must have had a signifant effect on the ET.
Great runs, glad you had a good day at the track. Most importantly it's consistent. Time for some power adder or higher compression or bigger cubic inch or lighter car. I am thinking mini tubs, wider tires and a steeper gear.