Agree with Howard - the low location of the wing enhances the low pressure effect generated by the GE tunnels. See the position of the wing on the all dominating Electromotive Nissan GTP cars.
SLC 24 Howard Jones
- Thread starter Howard Jones
- Start date
Agree with Howard - the low location of the wing enhances the low pressure effect generated by the GE tunnels. See the position of the wing on the all dominating Electromotive Nissan GTP cars.
Howard Jones
Supporter
It's funny that we are thinking about the Toyota. They seamed to have really done a lot of experimentation with the rear wing location and configuration. Included is some rear under car and diffuser pics of the same car. In these pictures the top wing element height is just about the same as the top of the cockpit with the lower element acting as a diffuser extension.
Robert. Do you think I should Photoshop the numbers off my car before I send in to Insurance. You have Photoshop right? Front and both sides...............hint.
Robert. Do you think I should Photoshop the numbers off my car before I send in to Insurance. You have Photoshop right? Front and both sides...............hint.
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Howard
If you add a wickerbill on the back then that will dictate wing height. Without wicker bill fairly close to stock height from Fran on race tail. Everything changes when adding street tail and or wickerbill.
It is all a guessing game with out wind tunnel or long yarn and pics. Sometimes like rain can help show the path as well.
I don't remember your GT40 having a wing, so a wickerbill would make a good add on.
SLC has a wing and a wickerbill probably will not help much. The wing is large enough to where you will need to work on front down force mostly.
If you add a wickerbill on the back then that will dictate wing height. Without wicker bill fairly close to stock height from Fran on race tail. Everything changes when adding street tail and or wickerbill.
It is all a guessing game with out wind tunnel or long yarn and pics. Sometimes like rain can help show the path as well.
I don't remember your GT40 having a wing, so a wickerbill would make a good add on.
SLC has a wing and a wickerbill probably will not help much. The wing is large enough to where you will need to work on front down force mostly.
Anyone made an extension to the diffuser to turn it into a true ground effects tunnel for their SLC?
Current Ford competition:
True... wonder if it couldn't be moved a bit further inboard.
Sure. But then it would likely be less efficient. It's all about the details, and what you are trying to optimize.
The rear suspension of an SLC was not designed for ground effects tunnels. The lower control arm and the lower rear of the chassis would be in the way of clean air flow. That is why the green car has the diffuser sticking out the back of the car.
Most modern GE chassis, even flat bottomed cars have little or no chassis components below the CL / behind of the drive axles. Thus even a flat bottom car 'could' have the diffuser start at the CL of the rear axle. (ala F1 cars)
Most modern GE chassis, even flat bottomed cars have little or no chassis components below the CL / behind of the drive axles. Thus even a flat bottom car 'could' have the diffuser start at the CL of the rear axle. (ala F1 cars)
Thanks for the clarification / education.
Howard Jones
Supporter
Continuing the punch list. I think I have the solution to the idle surge problem. Really it should have be a no brainer. My engine makes about 5-6 Hg at 1000RPMs. The Proform DP750 came with a 4.5 Hg power valve installed.
Clearly the power valve was right at the edge of opening all the time, changing it to a 2.5 made the car idle much more consistent, smoother and the idle mix screws are much more effective. Getting closer with every little thing.
I have also been doing some water temp running tests now that I have my temp plate tag. I am now up to a restrictor hole size of 1.25" in diameter. The car will hold water temp at about 190F now with a hard run down the freeway entrance, 70mph for about 4 miles down the freeway and a stop and go run thru the surface streets of about 15 mins back home. When I started I was over 220F by the time I got home and had to run the fans all the time. I found that one of the OEM fans wouldn't free wheel until I got over about 50MPH. I fixed that but I still think I need more CFMs from the fans and have be considering these.
Race Line, High-Flow Fan, 10", by Mishimoto
Clearly the power valve was right at the edge of opening all the time, changing it to a 2.5 made the car idle much more consistent, smoother and the idle mix screws are much more effective. Getting closer with every little thing.
I have also been doing some water temp running tests now that I have my temp plate tag. I am now up to a restrictor hole size of 1.25" in diameter. The car will hold water temp at about 190F now with a hard run down the freeway entrance, 70mph for about 4 miles down the freeway and a stop and go run thru the surface streets of about 15 mins back home. When I started I was over 220F by the time I got home and had to run the fans all the time. I found that one of the OEM fans wouldn't free wheel until I got over about 50MPH. I fixed that but I still think I need more CFMs from the fans and have be considering these.
Race Line, High-Flow Fan, 10", by Mishimoto
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Mishimoto is a good name and 1600cfm is pretty good for a 11" fan, but that blade style might be a little noisy, if that is a concern at all. Lol.
Howard Jones
Supporter
Back from the track. I took Francine to the track for her first time last weekend. we went down to Willow Springs in southern calif for the Cobra Owners Club of Orange County October event. I have run my GT40 with them a number of times and they are a really good group of people. Thank you all for a warm reception. I didn't even get a sideways glance at the Chevy during tech. Really a knowledgeable group of gearheads. The tech guy and I just talked about the car as he looked it over for about 20 mins and the he wanted to see the brake lights and I was good to go. "well done, really nice car"
Well so how did it go...........................? Very well! No real issues and nothing broke. I did have to tighten up a few things that went loose. Note to you all. Safety wire CV joint bolts and exhaust header bolts. Also really look over the car for this kind of stuff frequently during the first couple of sessions. Lots of grief if you don't catch this kind of stuff. We did and no serious problems came of it.
Check the engine room after each session the first couple of runs and keep on top of wheel bearings, lug bolts, wing mounts, suspension hardware, just about anything that can leak or come loose.
I did come up with a oil leak from somewhere on the front of the engine. I am thinking timing cover. Lost about a half of a quart over the weekend. I'll figure that out when I get the car up into the air on jack stands later.
The baseline setup:
F camber = -1.5, R camber= -1.0
F caster= set in center of mounts (Fran says this is about 6 degrees), R caster= centered it up also.
F toe 1/16" total, R toe = 1/16" total
F shocks = +10 clicks C and R, R shocks = +8 C and R
F springs = 750, R springs = 850
Anti roll bars, F not adjustable, R full soft
Rear wing = 2 degrees angle of attack
Tire pressure, all 30psi cold
1st session:
Add 10 gals gas
Ran car in slowest group and at end of grid lineup. Drove very slow (shift point 4.5K) to look over gauges and get a feel of the car. Water temp went to 200F, oil temp = 190F, grbx temp =<130F. Tires did not gain pressure and came back in cold. Nothing fell off. Wheel bearings, suspension parts, wing mount, lug bolts, etc. all normal. Car shifts good, stops straight, hands off wheel tracks straight, brakes very cold, new pads/rotors, required heavy effort. Had to pass two guys, I can't go THAT slow.
2nd session:
Shift point 5.5K, same baseline settings, water temp to 210F, oil 200F, grbx 140F, tires came up 1 pound, still cold, low grip. Started at rear of slow group again and gave them a half lap head start. Passed 8 of 16. This car is WAY too fast for slow group.
3rd session:
5.5K revs, tires F29 R29, went up to 31 both L's, 30 R's. water still at 220F, oil 200F, GRBX 150F. Brakes starting to work. Very stable under braking, still heavy effort but much better friction levels. Brakes feel safe. Good shifting. Engine getting some full power throttle on beginning of straights. Lots of power there. Best guess at this point is +100 on the GT40 I have. Slower cars are really holding me up and becoming dangerous at corner entry. Much higher end of straight speed. +30-50 mph. Maybe run next faster group? Passed all but 3 or 4.
4th session:
Add 5 gals gas
All baseline, except trimmed out rear wing to 0 AOA. Trying to fix front twitchiness at +130MPH. Ran tires at F28 R28 went to FL32 RL33 FR30 RR31 they got hot this time, grip much better. Straight speed +140 easy. VERY bad closing speed a couple of time. Need out of this group. Car still very balanced overall, No where near grip limits center of corners even with a little more foot in her. Can't feel grip limits anywhere despite running T9 at about a 100. Passed them all from way back on the grid and a 3/4 lap head start. Will mover to red group tomorrow morning for sure. Found a couple of loose CV bolts, and two header bolts fell out (found in bottom of engine room). fixed all. Temps still at session 3 levels.
Session 5:
Engine revs free, shift light @6300, F27 R28, Put 2 degrees back in rear wing. (twitchiness is going away with hotter tires..... I think ) Gonna push a bit this time in slow corners, try and find grip limits at least somewhere. Again at back of grid (still in slow group, fixes prevented me from changing groups) Pushed hard from 2nd lap on, passed all in 5 laps, This car will not slide anywhere. Huge grip levels as tires get hot. Very stable under hard (for me) braking from 140-150mph. Just rolling turn 1 in 4th and adding 33%-50% power at apex, fucking thing just takes a set and goes. Need 5th on front straight and down the hill into 8! Came up on little blue cobra at end of back straight at entry speed +50 easy. Just passed him off line down low into 9 (not supposed to do that) car just ran the bottom through 9 at +25-30mph over my best day in GT40 on correct line. No way I'm doing this group tomorrow. All temps still at previous levels except GRBX has gone to 190F. Car is feeling good. Oil leak from front of engine. Oil level good, pressure good, all lines/filter OK. Clean up and fix later.
Morning Sun:
Change to red group.
Re torqued all CV bolts. Nothing else loose oil leak still there, not getting out of car until sitting in paddock, engine room bottom catching oil. I think it is timing cover gasket or crank seal.
1st session:
Still on baseline setup, tires F27 R28 cold. Engine revs free.
Started at back of grid, passed two after tires came up to temp. Cars is still a long way from limits. Lifted on straights, If held full PWR too fast for first weekend. Brakes getting better still. Reset front bias to +4 turns from centered after 4 laps. Better. Temps still as yesterday except GRBX temp cold again <130F
Second session:
Add 5 gals gas
Left setup (all) same. Kind of went for it a little. Passed 5 guys and would have caught and passed a friend who just blew me away in the past. All temp held previous limits GRBX came up to 190F. Tires went to 32 lefts and 34 rights from 27 all. This track has two very fast right handers over 100 MPH.
Fuck Francis is fast. I have no idea how fast but that's enough for now. I am easy, and I mean really easy, 6-8 seconds a lap faster than I EVER went with my GT40 (I have done at least 10 days here with Betty).
The car never got sideways. I never felt ANY tire grip limits. The engine just keeps pulling despite a very moderate tune (carb isn't right.... really). Gotta be 500HP. In the case of turn 1 I am going through there at least 30MPH faster than with Betty. It's OK old girl, I know you are on street tires. Anyway there is a hung amount of speed left in the SLC. Maybe more than I will every be able to drive it well enough to get out of it.
For now I called it a good weekend, gave the wife a ride in the passenger session (slowly) loaded up and went home. The oil leak is still there and I really need to fix that. The carb will need some more messing with. As speed increase the spring rates will need to go up at least a 100 pounds. I am thinking of putting the 850s on the front and getting new 950s for the rear.
I still have no idea what to do with the roll bars. There was never a point where I could feel any imbalance. The areo question is up in the air (pun intended) but putting the wing setting back to 2 degrees AOA did feel better. Car never high speed pushed but my guess is it will near the limit.
My best guess is I'm at 70-80%. Really FUN though!!!!!!!!!!!!!!!!!
Well so how did it go...........................? Very well! No real issues and nothing broke. I did have to tighten up a few things that went loose. Note to you all. Safety wire CV joint bolts and exhaust header bolts. Also really look over the car for this kind of stuff frequently during the first couple of sessions. Lots of grief if you don't catch this kind of stuff. We did and no serious problems came of it.
Check the engine room after each session the first couple of runs and keep on top of wheel bearings, lug bolts, wing mounts, suspension hardware, just about anything that can leak or come loose.
I did come up with a oil leak from somewhere on the front of the engine. I am thinking timing cover. Lost about a half of a quart over the weekend. I'll figure that out when I get the car up into the air on jack stands later.
The baseline setup:
F camber = -1.5, R camber= -1.0
F caster= set in center of mounts (Fran says this is about 6 degrees), R caster= centered it up also.
F toe 1/16" total, R toe = 1/16" total
F shocks = +10 clicks C and R, R shocks = +8 C and R
F springs = 750, R springs = 850
Anti roll bars, F not adjustable, R full soft
Rear wing = 2 degrees angle of attack
Tire pressure, all 30psi cold
1st session:
Add 10 gals gas
Ran car in slowest group and at end of grid lineup. Drove very slow (shift point 4.5K) to look over gauges and get a feel of the car. Water temp went to 200F, oil temp = 190F, grbx temp =<130F. Tires did not gain pressure and came back in cold. Nothing fell off. Wheel bearings, suspension parts, wing mount, lug bolts, etc. all normal. Car shifts good, stops straight, hands off wheel tracks straight, brakes very cold, new pads/rotors, required heavy effort. Had to pass two guys, I can't go THAT slow.
2nd session:
Shift point 5.5K, same baseline settings, water temp to 210F, oil 200F, grbx 140F, tires came up 1 pound, still cold, low grip. Started at rear of slow group again and gave them a half lap head start. Passed 8 of 16. This car is WAY too fast for slow group.
3rd session:
5.5K revs, tires F29 R29, went up to 31 both L's, 30 R's. water still at 220F, oil 200F, GRBX 150F. Brakes starting to work. Very stable under braking, still heavy effort but much better friction levels. Brakes feel safe. Good shifting. Engine getting some full power throttle on beginning of straights. Lots of power there. Best guess at this point is +100 on the GT40 I have. Slower cars are really holding me up and becoming dangerous at corner entry. Much higher end of straight speed. +30-50 mph. Maybe run next faster group? Passed all but 3 or 4.
4th session:
Add 5 gals gas
All baseline, except trimmed out rear wing to 0 AOA. Trying to fix front twitchiness at +130MPH. Ran tires at F28 R28 went to FL32 RL33 FR30 RR31 they got hot this time, grip much better. Straight speed +140 easy. VERY bad closing speed a couple of time. Need out of this group. Car still very balanced overall, No where near grip limits center of corners even with a little more foot in her. Can't feel grip limits anywhere despite running T9 at about a 100. Passed them all from way back on the grid and a 3/4 lap head start. Will mover to red group tomorrow morning for sure. Found a couple of loose CV bolts, and two header bolts fell out (found in bottom of engine room). fixed all. Temps still at session 3 levels.
Session 5:
Engine revs free, shift light @6300, F27 R28, Put 2 degrees back in rear wing. (twitchiness is going away with hotter tires..... I think ) Gonna push a bit this time in slow corners, try and find grip limits at least somewhere. Again at back of grid (still in slow group, fixes prevented me from changing groups) Pushed hard from 2nd lap on, passed all in 5 laps, This car will not slide anywhere. Huge grip levels as tires get hot. Very stable under hard (for me) braking from 140-150mph. Just rolling turn 1 in 4th and adding 33%-50% power at apex, fucking thing just takes a set and goes. Need 5th on front straight and down the hill into 8! Came up on little blue cobra at end of back straight at entry speed +50 easy. Just passed him off line down low into 9 (not supposed to do that) car just ran the bottom through 9 at +25-30mph over my best day in GT40 on correct line. No way I'm doing this group tomorrow. All temps still at previous levels except GRBX has gone to 190F. Car is feeling good. Oil leak from front of engine. Oil level good, pressure good, all lines/filter OK. Clean up and fix later.
Morning Sun:
Change to red group.
Re torqued all CV bolts. Nothing else loose oil leak still there, not getting out of car until sitting in paddock, engine room bottom catching oil. I think it is timing cover gasket or crank seal.
1st session:
Still on baseline setup, tires F27 R28 cold. Engine revs free.
Started at back of grid, passed two after tires came up to temp. Cars is still a long way from limits. Lifted on straights, If held full PWR too fast for first weekend. Brakes getting better still. Reset front bias to +4 turns from centered after 4 laps. Better. Temps still as yesterday except GRBX temp cold again <130F
Second session:
Add 5 gals gas
Left setup (all) same. Kind of went for it a little. Passed 5 guys and would have caught and passed a friend who just blew me away in the past. All temp held previous limits GRBX came up to 190F. Tires went to 32 lefts and 34 rights from 27 all. This track has two very fast right handers over 100 MPH.
Fuck Francis is fast. I have no idea how fast but that's enough for now. I am easy, and I mean really easy, 6-8 seconds a lap faster than I EVER went with my GT40 (I have done at least 10 days here with Betty).
The car never got sideways. I never felt ANY tire grip limits. The engine just keeps pulling despite a very moderate tune (carb isn't right.... really). Gotta be 500HP. In the case of turn 1 I am going through there at least 30MPH faster than with Betty. It's OK old girl, I know you are on street tires. Anyway there is a hung amount of speed left in the SLC. Maybe more than I will every be able to drive it well enough to get out of it.
For now I called it a good weekend, gave the wife a ride in the passenger session (slowly) loaded up and went home. The oil leak is still there and I really need to fix that. The carb will need some more messing with. As speed increase the spring rates will need to go up at least a 100 pounds. I am thinking of putting the 850s on the front and getting new 950s for the rear.
I still have no idea what to do with the roll bars. There was never a point where I could feel any imbalance. The areo question is up in the air (pun intended) but putting the wing setting back to 2 degrees AOA did feel better. Car never high speed pushed but my guess is it will near the limit.
My best guess is I'm at 70-80%. Really FUN though!!!!!!!!!!!!!!!!!
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Sounds like a fun couple days!
Congrats Howard sounds like you did everything right. Do you know what time you were doing ? I will be at willow springs in two weeks with my Cobra for the VARA Big Bore Bash
Maui
Maui
