Goodbye 3000rpm, hellooo 2600rpm!

[BillyM]

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7950341619

...guess I will have to do a truetrac install at some point in the near future.

--BillyM

[RaptorRacing]

Sweet find bro...do you know if he has anymore???

[BillyM]

Will ask. =)

--BillyM

[dogstar]

nice find, thatd go awesome on a turbo car :)

[Supra Bob]

Umm... not to be a kill joy Billy... but I thought Autocrossing was all about fast acceleration coming out of turns? Going to a higher (Numerically lower) ratio is gonna hurt that in a big way... I mean, I totally understand if this isn't your autocrosser.. lord knows it bugs the hell outta me cruising the highway at 3300rpms..

[williamb82]

also, going from a 4.30 to a 3.58 will drop the rpm's alot more then that.

[Daves2JZGTE]

thats what i have in my car and i dont think you wont that in a 5m NA



Dave

[BillyM]

"NA"? Try "NO"....

*peers into parts-closet.

turbo, manifold, oil lines, fuel pump, 2035 rrfpr, 210cc inj, bov, 2.5" intake piping, starion IC, full chimpy exhaust, wideband/datalog, 7m crank/rods moded for early5m block/pulley, mhg, arp's, 1mm OS valves, and now starting on parts for a diff build. need pistons, a clutch, and now a truetrac.

...if only bob would sell me his freakin msd-btm....

--BillyM

[CELICA XX]

I thought Autocrossing was all about fast acceleration coming out of turns? Going to a higher (Numerically lower) ratio is gonna hurt that in a big way... I mean, I totally understand if this isn't your autocrosser.. lord knows it bugs the hell outta me cruising the highway at 3300rpms..
Imagine how I feel in the 86 MR2 at 4000+ RPM on the highway!

[williamb82]

funny thing is even with a 3.727 i cruise ~3500 rpm on the bridge from tampa to largo. dont know how fast im going as the speedo cable is busted but i doubt youll see lower rpm's n the highway, prolly the same rpm, just higher speeds. :P

[BillyM]

...yea, I'll be damned if I know where to get a 3.58 speedo gear... that means I'll just add 14% all the time *gets calculator out

--BillyM

[KesekiSupra]

i thot there were places u could take the car where they fix that. i dont know exactly what they do, but if ur cars spedo is off, they can fix it. gah morning hurts my brain

[hereiam]

I'm not annoyed at all by the revs. I love the sound and the response but that's just me

[dogstar]

nothing wrong with the revs, if your driving hard, but if you want to retain a little better fuel economy, the lower gears should really help.

plus with a turbo it should load up better when pulling in high gears.

[Suprajayaz]

i thot there were places u could take the car where they fix that. i dont know exactly what they do, but if ur cars spedo is off, they can fix it. gah morning hurts my brain

When I converted to 3.73's during the 7mgte swap, I looked all around for speedo correction solutions.. from changing the speedo drive shaft gear which was not enough for a 85P-type as I think you have to swap the tailshaft gear also.. Seemed like more work than I was willing to do.. Called a few speedo shops in town and for like $100 - they will build/install a small adjustable box + cables to go between the tranny and the speedometer that allow adjusting the speedo to read correctly..I ended up just going down the road with a friend with a good GPS and we correlated between the GPS and the car speedo.. It was exactly 10% off (stock wheels with Mich Pilots).. ie. 60mph on speed was 66mph on the GPS.. did this from 35 up to about 80.. so now just add 10% in my head.. No cost..no tickets either...Jay B in AZ

[Supra Bob]

Billy..first off... I forgot to mention in the first post, that I do think you made an awesome score and am in no way downplaying that fact.

BUT I am concerned that you may not end up with the results you find satisfactory. By changing to a higher gear ratio, the car now has less torque multiplication going on at the tires, and will require MORE work by the motor to achieve the same results. For example: (and this is incredibly simplified only due to my laziness at the moment)

A car gets 100 HP at the input shaft of the rear. with a 4.00:1 gear ratio, the diff multiplies the power by 4, thereby allowing the wheels to apply 4 times the force and effectively have the ability to do what 400 HP could do with a 1:1 ratio. If in the same situation, you change to a 3.00:1 gear ratio, your only getting 3 times the torque multiplication.

Now, I will agree that this will put more load on the motor, causing more heat, which causes faster turbo spool up, but is the added power going to be enough make up for the loss of mechnical advantage? Unless your doing a radical super high boost application with something like an SP-87 or something, I think the end result will be slower times for you coming out of turns..and as we both know, exit speed on a turn is EVERYTHING. I mean, if I remember, William B.'s first post after his 3.73 install was something to the effect of "WTF!?!? My 60' times are shit, and my overall times are the same!" I have to believe that the results would be the same on an autocross track.

Personally, I would stick with the 4.30's or at most, go to a 4.10. I know it means less boost and less power to the tires at lower RPM's, but when traction is already an issue, why compound it with more power when you can't use it?

Anyway, thats just my $.02. Trying to bring to light some things you may or may not have already thought of :)

[Donn29]

wasnt there a big thread on here about it. i think only the tranny side gear needs to be changed.

also 3.58 is a big drop, mpg will propably only come up a bit. depends on many things though, would be bad on a 5m thats for sure. i sure wanna hear about it!
is this diff gonna be raced? sounds like it.

[BillyM]

Yea... I figure, I can reduce the the gearing by 14.5% but at the same time I have to double the horsepower. ...things have changed bob. I have some big plans falling together for one of the faster 2-valve head setup I have heard of, minus maybe RussM... The rrfpr setup will be a shake-down for the new motor only, and an interim while I'm busy bulletproofing the drivetrain the rest of the way, (big) turbo and standalone will follow closely.

I have enough 4.1 diffs lying around I can always build another if I get heavy into racing...

--BillyM

[williamb82]

well, i expected the 60ft drop, but not by that much. i also had other issues that night. my mph was faster by 5mph but the time was slower by ~0.4 sec. over what i ran in the red car. 13.7@97 vs 14.1 @102 in the black car(same boost on both cars). black car obviously has much more power, just wasnt getting the traction off the line, and fuel cut didnt help either. the 20th isnt far away and ill have new times then.

[Supra Bob]

Billy..Thats awesome!! I am glad your plans are falling into place! Can't wait to hear about it and see some pics and video. Sounds pretty exciting.

[batmobile]

im pretty sure billy knows what hes doin. with all that added power, he can have a lower gear ratio, and get decent fuel economy taboot. Billy are you going to set this car up to be an Auto-xer? or have one mean street car?

Ive also noticed you have purchased quite a bit of audio stuff on ebay including a lot of fiona apple CD's. I think billy likes to play Fiona when he auto-xes! :lol:

[BillyM]

Hobby1: Supra
Hobby2: High-end Audio

...gotta have tunes that sound good. Fiona Apple has such a presence in her voice, something many singers now-days could only wish to acquire. ...not to mention her lyrics. I consider her more of a poet than a singer. You spend a couple-few grand on equipment, not about to play some mainstream hip-hop bullshit.

Aimee Mann, another awesome female singer. Pick up the "Magnolia" soundtrack if you have a system who's midrange you want to show off. Her rendition of "One" is one of my favorite tunes. Another favorite artist of mine is Eva Cassidy. If you like blues or jazz and dont mind a little female singer, pick up "Live at Blues Alley" by her. Her range amazes me... Norah sings me to sleep every night as well (the first CD, the second stunk).



CARS!

Eh, this wont be a competetive autox car. I plan to pick up another, more competetive car later down the line, but my last season was a bummer. $20, and you make 4 runs... Not my kind of good-time. My region really needs to limit entrances, or split into two regions to keep me interested...

...as for the gearing, I just want to cruise to vegas at 3krpm well above the speed limit... F the drag performance...

--BillyM

[batmobile]

Thats cool! I cant believe you drive from tennesee all the way to vegas! I know its certainly an event to be at, but damn, that must be one fun cruise.

[Supra Bob]

im pretty sure billy knows what hes doin.


I have no doubt Billy knows what he is doing. Just making sure a fellow gearhead had looked at all angles of his project!

[85 rat rod]

gas milage, i dropped to a 4.10 and not only does my take off suck, but my mpg bites (and all the fuel/smog stuff is in perfrect order) on the subject of audio, pick up a copy of googoo dolls dizzy up the girl, and the counting crows august and everything after, if you want to show off clear highs and well tuned lows, (never been a big fan of midrange, but thats just my style) i learned from some of the best, but have never made enough money to show off my style lol


Edit: but then whats to say the junk yard car i pulled the diff from was its origional diff, it was an 84 p type auto, so i have no clue, although i know its not lsd

[BillyM]

Have any hard data behind that, measuring distance between fill-ups and dividing by what it takes to fill it?

Music, done and done. How can you not call those "midrange-heavy"? Acoustic #3 is a really fantastic song, Bullet Proof is a good dynamic fast song. ...big fan. As for Counting Crows, Perfect Blue Buildings is one of my favorites. Again, midrange-heavy if you ask me....

--BillyM

[85 rat rod]

no not really, but being a sevierly beaten stock engine, my low end torque suffers, and being that the region i live in, and my lack of highway use as more of stop and go, and waiting at lights, that slow over gassed takeoff isnt helping much (but also coming to terms with a car that never had great gas milage in the first place) but now that you mention it, i think i just might just top my car off up on payday, and reset the trip meter, the ride ends when the orange light comes on) given gas prices, and my wages at work, i live between 1/4 and E, its a bad habit, and i would be better off just filling it up (the second half of the tank seems to go quicker anyway BTW, is there a code somewhere on the diff casing that will tell me what ratio it is ect, (is it the same code you would find on the firewall?)