Best Performance improvement (cheap)

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Best Performance improvement (cheap) - 12/23/2007 5:54:01 AM    IXLR8   Posts: 376 Joined: 12/27/2005 From: Katy, TX Status: offline   I thought I would start a new thread on this. (Last one I promise...) Changed tires from 235/55-18 to 235/50-18, new tires are .93" lower than factory original 0 to 60 went from 5.7 to 5.4 recorded times 5.38, 5.33, 5.40, 5.41 1/4 mile went from 14.22@98 to 13.82@105mph recorded time were 13.85@104, 13.83@104 Intermediate times can be posted. The only mod on the 2006 Charger Daytona, is a Mopar low restriction drop in replacement air filter (K&N makes them for Dodge) No headers, no CAI, no other physical modes.  However the latest Super Chips was loaded. WOW! < Message edited by IXLR8 -- 12/24/2007 5:17:50 AM > _____________________________ I feel a need... a need for SPEED !! GMG Daytona Only insecure people list mods... Post #: 1

RE: Best Performance improvement (cheap) - 12/24/2007 12:00:28 PM    Midnight Blue   Posts: 167 Joined: 6/4/2006 Status: offline Maybe I missed it in the last thread but what brand and model tires did you put on. They look to be doing good for you ( -4/10's and +5 mph in the quarter is not too shabby). Redbeard (in reply to IXLR8) Post #: 2

RE: Best Performance improvement (cheap) - 12/24/2007 12:39:09 PM    IXLR8   Posts: 376 Joined: 12/27/2005 From: Katy, TX Status: offline Everyone seems to miss the point.  It is not the tire compound, it is the change in diameter.  Essentially it gives me a higher final drive ratio.  The magic seems to be in that the smaller tire diameter seems to make the car better match the engine torque and horsepower curves, allowing better acceleration.  Instead of adding HP, using CAI, headers, or whatever. Modifying the final drive ratio by changing tire diameter, instead of changing say, the rear end ratio's in the differential yielded an unexpectedly large gain in performance. It also lowered the car by .5" reducing drag. FYI the tires are Michelin Pilot Sport 235/50ZR-18 97Y I think it is the tire size, not the type that made the difference. If I did not see it with my own two eyes I would not believe it!  < Message edited by IXLR8 -- 12/24/2007 12:45:42 PM > _____________________________ I feel a need... a need for SPEED !! GMG Daytona Only insecure people list mods... (in reply to Midnight Blue) Post #: 3

RE: Best Performance improvement (cheap) - 12/26/2007 3:40:40 PM    MangoInTX Pat & Amandas Wedding Fund Contributor Posts: 2727 Joined: 4/10/2006 Status: offline Got the message and agree with it totally. Now I have the stock rims free I will put some smaller than stock drag radials on them for the track. Do you think 27.25 diamater is the sweet spot? (in reply to IXLR8) Post #: 4

RE: Best Performance improvement (cheap) - 12/27/2007 3:06:56 AM    IXLR8   Posts: 376 Joined: 12/27/2005 From: Katy, TX Status: offline I have no clue...  But you could push me over with a feather with the results I got... Totally unexpected.  my 60 foot time was a 2.62, and I did have wheelspin.  So if you could "hook-up" better, you may get low 13's... _____________________________ I feel a need... a need for SPEED !! GMG Daytona Only insecure people list mods... (in reply to MangoInTX) Post #: 5

RE: Best Performance improvement (cheap) - 12/27/2007 6:04:11 PM    IXLR8   Posts: 376 Joined: 12/27/2005 From: Katy, TX Status: offline Hey Mango, after thinking further, it may not be such a good idea to put smaller tires on the back...  This will leave the car with a poor aerodynamic profile, front is taller than the back.  This would be good for weight transfer to the rear wheels on launch, but as you approach 100mph at the end of the 1/4 mile your front end might get light, and the air going under the car may cancel out any improvements... I'll attach a photo next time, but I swear it looks like I put a lowering kit on my car.  Yes I know it is only a .5" lower, but you can really see it.  It should lower the C/D of the car also with less frontal area... _____________________________ I feel a need... a need for SPEED !! GMG Daytona Only insecure people list mods... (in reply to IXLR8) Post #: 6

RE: Best Performance improvement (cheap) - 12/28/2007 5:39:57 AM    MangoInTX Pat & Amandas Wedding Fund Contributor Posts: 2727 Joined: 4/10/2006 Status: offline I plan to put the narrowest tire I can on the front rims to balance it out, just have to make sure the tire height is right. (in reply to IXLR8) Post #: 7

RE: Best Performance improvement (cheap) - 12/28/2007 8:17:06 AM    IXLR8   Posts: 376 Joined: 12/27/2005 From: Katy, TX Status: offline That would be COOL! Two thumbs waay up! _____________________________ I feel a need... a need for SPEED !! GMG Daytona Only insecure people list mods... (in reply to MangoInTX) Post #: 8

RE: Best Performance improvement (cheap) - 12/29/2007 2:11:13 PM    John M Posts: 469 Joined: 5/24/2007 From: Milledgeville, GA Status: online Just me, poking my head back in this section of the site   I posted the exact same thing to the truck guys a few weeks ago and basically got nowhere.  I also took a full inch off the overall height of my tires (thereby losing a whole half-inch of vehicle height) and noticed a very noticable improvement in acceleration.  By my poor math skills, it's like me going from a 3.92 rear to a 4.03 or so.  Since they're 305/50/20, it's not like they're exactly tiny or hurt the truck's performance in non-pavement applications.  I don't pretend to be a mud bogger so I'll gladly take the increase in power. _____________________________ 03 Ram QC 4x4 Hemi / Laramie / Cooper Zenon 305/50/20 - Superchips, ebay 3.5in 1-pc intake, LED tails (OEM-style, not ricer clears) (in reply to IXLR8) Post #: 9

RE: Best Performance improvement (cheap) - 12/31/2007 11:35:36 AM    Midnight Blue   Posts: 167 Joined: 6/4/2006 Status: offline I wouldn't completely discount the tire compound component. True that with a shorter tire, you are effective lowering the final drive ratio (numerically raising it) resulting in more torque multiplication, but if the tire slips you lose power. The Pilot Sport is marketed by Michelin as a performance tire while the original Michelins are marketed as touring tires. The touring tires are tuned more toward ride quality than performance tires. Things like wet traction and tread life have a higher priority for a touring tire. If you check the two tire series out on the Michelin web site, you'll see these differences. Things like sidewall flex and tire compound are big components in making tires do what they're designed to do. More than once just replacing tires have made radical changes to the personality of my vehicles. I had a set of tires on my pickup that wouldn't grip at all. It was a real handful to drive with those donuts. It would get squirrely if I ran through a puddle of dog wee (chuahua wee at that)! Made winter driving an adventure. Fortunately, their wear was as bad as their traction so after a couple of years I replaced them with a set of Pirellis. We're talking day and night here. I could now accelerate up drives and on ramps that I used to have to feather the throttle to keep from breaking the tires loose on. I would have gotten the Michelins but the tire store only had 3 of those on hand and 8 Pirellis and I didn't want to have to come back. I realize that this is a more extreme example but it does illustrate the differences that rubber compounding makes. I think that you will find that a combination of the shorter tire AND better grip has given you the numbers. You might want to play with air pressure to further tune this. Since we are talking straight line racing, you could lower your rear pressures to reduce rolling radius (lowering the car and effective lowering drive ratio more) and plant more tread on the track. At 25 psi or lower the tire pressure monitor will whine but you'll know why. Bump up the fronts to max rated pressure to reduce rolling resistance. Don't forget to reset the pressures before you drive home though. I've been considering a set of Pilot Sports to replace those on my car and my wife's Chrysler 300m Special. I like the wet traction of the Michelin's (important here in the Pacific Northwest). How would you compare the two tires for ride quality? I'm asking this more for my wife's car. I can trade a smoother ride for better handling but she likes the ride quality that she has. If there isn't a big difference in ride, she would probably be game to go with the performance series. Have fun and have a safe and Happy New Year!! Redbeard (in reply to IXLR8) Post #: 10

RE: Best Performance improvement (cheap) - 12/31/2007 5:48:25 PM    IXLR8   Posts: 376 Joined: 12/27/2005 From: Katy, TX Status: offline After further testing (if anyone still cares...) I found that in order the make the speedometer match the actual speed, I had to enter 26.5" into the SC tuner as the new tire diameter.  The speed correction was done using a Garmin 760 GPS and driving at a range of speeds from 40mph to 80mph, and comparing the speedometer to the GPS.  This was done on flat roadways over the period of about two hours. Anyone have an idea why 26.5" instead of the tire manufacturer computed 27.25" ?  Super Chips programmers please feel free to chime in.... _____________________________ I feel a need... a need for SPEED !! GMG Daytona Only insecure people list mods... (in reply to Midnight Blue) Post #: 11

RE: Best Performance improvement (cheap) - 12/31/2007 8:40:21 PM    Texas Crewd   Posts: 37 Joined: 8/18/2007 Status: offline Thought you might find this interesting http://www.corvetteactioncenter.com/tech/tools/rearend.html http://www.ajdesigner.com/phpgear/gear_equation_tire_radius.php I'd love to drive this car with a set of 4:10s warm up in 1st and drop it in 2nd _____________________________ Mine: 04.5 3500 QC Slt 4x4 DRW 6spd white w/ ranchhands front and rear Hers: 07 Charger RT, R&T package, black on black Ours: 73 CJ 5 V8 4spd,D44 front, D44 floater rear, 10k MM, ARBs front/rear, 6 point cage on 35x15 swampers 4:88 gears. (in reply to IXLR8) Post #: 12

RE: Best Performance improvement (cheap) - 12/31/2007 10:18:48 PM    John M Posts: 469 Joined: 5/24/2007 From: Milledgeville, GA Status: online quote: ORIGINAL: IXLR8 Anyone have an idea why 26.5" instead of the tire manufacturer computed 27.25" ? I've seen it mentioned that it has to do with the tire being loaded vs. unloaded.  Basically the sag in the sidewall caused by the vehicle's weight means the effective diameter is smaller than the raw tire dimensions. Now that you've pointed it out I'll need to borrow a GPS to see how far off my speedo is now. _____________________________ 03 Ram QC 4x4 Hemi / Laramie / Cooper Zenon 305/50/20 - Superchips, ebay 3.5in 1-pc intake, LED tails (OEM-style, not ricer clears) (in reply to IXLR8) Post #: 13

RE: Best Performance improvement (cheap) - 1/1/2008 6:54:15 AM    IXLR8   Posts: 376 Joined: 12/27/2005 From: Katy, TX Status: offline Hey Redbeard, In a straight comparison of ride qualities between the stock Michelin tire and the Pilot Sport, I can say: The OEM tires are quieter, but there is not a great difference.  The OEM tires also have a better "on center" feel. The wet traction on both tires is superior, the OEM tires deteriorated rapidly as the tread wore down, at 28,000 the wear bars were almost showing, but the wet performance had dropped significantly. I am more of road racer, than a quarter miler, so the Pilots do provide a tremendous amount of traction in the curves, but the the OEM tires were some of the best I have ever seen. The straight line acceleration with the smaller tires is truly amazing.  But they seem to have equal traction from a standstill, relatively poor, but that is due more to the excessive weight of the car than the tires. The Pilots were absolutely worth the money I paid!  The effect of increased acceleration is apparent at all speeds.  This is quite possibly the best "sleeper mod" yet discovered. I would put my totally stock car up against someone with a CAI, long tube headers, and a cat back system, and feel confident that I could take 'em...  Boasting?  maybe... or maybe not! _____________________________ I feel a need... a need for SPEED !! GMG Daytona Only insecure people list mods... (in reply to John M) Post #: 14

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