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Post by windsor on May 4, 2016 12:40:53 GMT -5
Drove the car to test and tune last night. Best pass was 6.54 @ 104 (1.40 60') Jetting was lean but didn't bring my jets with me figuring the track wouldn't be in very good shape on the opening day (late start due to paving the track in concrete!) I went mostly to get teched for the year, it passed so I can go 6.0 and not wait in line at tech every time. Anyway I pulled the air cleaner and the car slowed about 1 mph. It also slowed down when the air temps came down. I put the interior back in the car and put a hood on it since the last time out which added about 100lbs, so it's running about the same as it did last year when it ran 6.40 in similar weather. Jetting is currently @ 88/97 but I have the air bleeds leaned way out. The carb tune is something I'm experimenting with and nothing like any of the E85 carb builders use (or recommend) so I won't post my tune up until I get the wide band on it and make sure it's a safe all around tune. I tried the recommended tune ups and the car ran well at WOT but did not get great gas mileage on the street. It was fat in the idle and transition areas with those tunes. I've picked up about 5 or 6 mpg with my tune up and the engine is a lot crisper. It's just a hair lean up top but I think a main jet change will fix that. More to come....... |
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Post by windsor on May 18, 2016 22:52:44 GMT -5
Well I finally was able to get the wideband up and working. It's an old FJO unit with an NTK sensor. Holley purchased them and just rebadged the FJO unit. Anyway I was able to log some data and it shows I'm still a little lean. I'm going to take Adams advice and tune it to gas numbers as this one reads in AFR on the display. I know it bases this data off lambda but again only shows AFR when datalogging. I tried fattening up the carb a bunch to run in the 11.7-12.2 (gas scale) range as some well known tuners have suggested and the car fell on it's face. As I got closer to the 12.5-13.1 range the car really woke up. Again the idle feed restriction, air bleed size, emulsion placement are my own and seems to work much better than what is usually run in E85 carbs. I'll list the specifics after I do a little more track testing this friday. I've attached some wideband data from a second-third gear roll on (was on the thruway) to show what it's doing at max rpm, which in this case is 6600-6700. Again I think I'm still a little lean but I'll experiment this Friday at the track to verify. Plugs looks good.  |
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Post by windsor on May 25, 2016 7:08:29 GMT -5
Caution - long read
I made it to the track a couple of times since I last posted so I thought I would share some information on track times and carb tunes. Before I do I thought I would provide a little history. The first time the car was at the track was last year at the end of the season. The air temps were in the low 50's, I had a 15 MPH tail wind and track prep was good. Fast forward to this year and my average times have ranged from a 6.47 (1/8 mile) to 6.65 in conditions that haven't been quite as good as last season. Now for the update. I went to the track last week Wednesday with the old tune up (listed below) in the carb and the car went average of 6.65 with a best of 6.61 @ 104 MPH (1.42 60') leaving @ 4k on the T-brake. The car felt real lazy down low as it did last year when it ran 6.40. By the way that 6.40 was one of only two passes in the 6.4's with rest in the 6.5-6.6 range that day.
Friday I put my tune back in the carb and couldn't leave any higher than 3500 without blowing the tires off. Tracks conditions were similar to Wednesday. The engine feels much crisper is obviously making a bunch more power down low with my tune. I was able to datalog my runs on Friday but didn't get a chance to get Wednesdays info at the track. I can tell you that the car runs much fatter down low and in the middle that it does with my current tune.
Sometime ago I read an article on how to optimize a holley gas carb to increase performance and especially gas mileage (remember this is a street car). To make a long story even longer, they did this by reducing the idle feed restriction from .036 (stock) to .020 and changing high and low speed air bleeds to arrive at an ideal air fuel ratio at idle, cruise and wot. I had already done this to a gas carb and went from 12 mpg to 21 mpg, so I figured I would try it with an E85 carb. So far it seems to be working although it's not 100% dialed in, it's close. I'll post more datalog info later but I've listed my old and current carb tune below. For the record the engine liked 31 degrees total timing with the latest tune. I'm sure I've left a bunch of info out but will post more later
Old tune:
850 Proform
MJ 88/97
PV -3.5 - 4 Window
QFT E85 Metering Blocks (old version)
Emulsion .028,b,.028,b
IFR .043
.180 Booster (stock dog leg)
.130 Needle/Seat
HSB/LSB 28/61
Best time this year 6.61@104 - 1.42 60' (4k launch)
Gas mileage: 6-8 MPG
Current tune:
MJ 91/99
PV - 3.5
Metering blocks (same)
Emulsion B,.028,B,.028
IFR .024
.180 Booster (same)
.130 Needle/Seat (same)
HSB/LSB 55/25 (No not a misprint)
Best time 6.47@105 - 1.39 60' (3500 launch) (similar track conditions as above)
Gas mileage: 12-14
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Post by windsor on May 26, 2016 9:33:12 GMT -5
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Post by windsor on May 26, 2016 23:34:02 GMT -5
Here's where I ended up on the current tune. AFR is averaging 12.5 - 12.7 - I played around with the HSB to dial it in a little better. The front two cylinders run a little leaner, especially #5 (front driver side). The HSB bleed in the front left was changed from 55 to 48. Some people stagger jetting but this is a bunch easier and worked well. After the change the AFR came down from around 13.0 to the 12.5 -12.7 mentioned above. This is an 1/8 mile pass. I believe it went 6.47 on this pass.  |
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Post by triplenickel on May 28, 2016 17:59:10 GMT -5
Very interesting! Thanks for sharing this info.
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Post by windsor on May 29, 2016 20:14:55 GMT -5
Very interesting! Thanks for sharing this info. No problem. The current tune seems pretty consistant pass to pass. I've listed the last couple while playing with the timing. It probably would have run within a couple of hundreths or less if I had not been dialing in the timing. I tuned for best ET (not MPH) based on Mark Sullens recommendation. I'll have to do more testing but for now this is one recommendation I agree with. I don't know if anyone else has experienced something similar but I'd appreciate any feedback. Thanks again. Timing @ 30 - 6.49 @ 104.97 31 - 6.47 @ 104.91 32 - 6.48 @ 104.72 33 - 6.49 @ 104.63 34 - 6.53 @ 104.43
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