I will second that. A HUGE difference in feel. I personally prefer the low ratio box, and would rather take those medium turns in third than second and run it up higher. It makes a us spec 16 valve feel very strong, esp. when short shifting the box. There is a reason why GTs have that lower ratio, Horatio.

 

Daniel so you think Porsche was on to something when they offered two different 5 speeds Imagine that !

 

Oh yeah, limited slip in the rain means you coast through the apex . Too much throttle is easy to catch, though it can snap fast. Jim B was kind enough to send a limited slip out to me recently, and of course the first ride was in the wet and it caught me out. That car is destined to be a DE track toy, and I don't think I would bother on an unblown street car unless it came that way.

 

I don't really do this anymore, but to illustrate my point I'll point out to you something that happened a few years ago up in Orlando.

On a regular basis, the '94 and up Camaro's used to pick fights with me on the streets of the "City Beautiful". On a regular basis I wound up handing them their hats too. Then one night, an F-body came along that managed to really spank my S2. At the next light [typical in Orlando- 1/4 mile later or less, and for no particular reason that I could see-?], I wound up next to him. Openned windows = yelled question over growling exhausts:

"How did that just happen?"

"She's stock but the exhaust and the 4.11 gears in the back"

Hello? That car probably had less horsepower than mine, a top speed of around 125 mph [gearing limited], but it left me for dead. I'm not into drag racing at all, though I don't mind the occasional "stoplight grand prix- thing" either. A set of his gears for sale that would fit my G28-10 would really get my attention, since I'm sure they'd enhance my "personal roller coaster"....

N!

 

Normy, talk to Scott M. about his 3.09s. You can see the math of what they'd do to your car in my Rennlist page in my sig line.

I had a smack talking redneck with a Dodge 2500 CTD challenge me to a drag race. I said I won't drag him, but I'll race from 50-150. He laughed and said I was a siisy. He had said earlier that his turbo didn't spool until he was in second. I replied with an offer of 30-130. At that point he admitted he ran out of 5th gear at about 110mph. A girl standing next to us said "even my Matrix will do 130". We both laughed and the guy ran away (really, he ran away because we were laughing at 'his manhood'). Anybody can put low gears into anything and make it go fast in a street drag.

 

Yes Jim, sometimes I imagine my S4 geared as a GT. Everything else I can fake or approximate.

As to Porsche being on to something, sometimes we should modify our expectations to match the car, and other times modify the car to our expectations. Different strokes and all that, still some were made more equal than others. Once you've had a taste, there is no going back.

Now that I have modified my 80 to emulate the very brown ''Bailey Special'', I can see the S4 will need some upgrades. It's a slippery slope.

 

Is this why mark anderson even with a 2.75 gts box, has not posted a better time at willow springs with it vs the 2.2?? (until he put on 60more hp, and then it dropped only about .5 seconds! to 1:23.5 for a best!)

I know you get this stuff, but dragging the 911 cup car into the mix just confuses things. I would love to have a close ratio gear box in my car like the GT3cup car. thats an entirely different debate . close ratios keep the engine at or near max hp for as much of the time as possible. its all about maximizing time spent at near max hp. max torque means nothing, but can indicate a flatter hp curve, where you can use wider gear spacing as effectively as a peaky hp curve like a porsche GT3cup car. the cup car will have more shifts, but both will acceleratate the same with the same average hp put to the ground over any speed range.

Playing with rear ends, as we proved many times, gives an advantage of Hp out of the shoot, but after the 1st gear shift, there are a series of trade offs. its not a "top" speed issue, its a range of speed issue, based on gear spacing. if the two cars have the same engine, the acceleration performance can be an advantage for one or the other depending on the vehicle speed range used.
plug in the numbers for 60-100mph for a 2.2 vs a 2.75. you will find the trade offs cancel and they are about equal. try 60 to 120. the trade offs favor the 2.2 . (based on near 300rwhp +/- 10%) its speed range dependant, its HP and expected acceleration rate dependant , as i always say, it depends.

However, ignoring grip and traction, the superlow 1st gear can allow you to reap benefits that will give the best ET's, but CAN give a lower top trap speed.
(assuming you traded a higher first gear ratio for not being near max HP at the end of the quarter, which is really what draggers agonize about. ideally, with a given spacing, you want to get to the finish at near redline, but launch with as high of numeric ratio of a gear as possible )

agian, if you think about it, its all about maximizing hp, not engine torque.

4:11, 3.09, 2.2, it doesnt matter. what matters is the gear spacing. more importantly, look at the speed at redline of each gear. Did you know that the
2.2 :1 porsche 928
3:07 :1 viper
and the 3.42:1 corvette (z06)
ALL HAVE ONE THING IN COMMON?????

yes, they all have
1st gear to near 60mph (actually 928 is lower here)
2nd gear near 88mph (928 lower here too)
3rd gear near 120mph (928 is slightly lower here)
4th gear near 157mph and (about the same vs the 928)
5th near 220mph (pretty close here too)
However, both vet and viper have 6th gears that can go to 300mph+

so, what does this tell us??? it tells us that the design of the 2.2 is pretty darn good, especially if a '06 vet and viper use the almost same exact gear spacing and absolute ratios!!!
it also tells us that overdrive is not the most important factor in gas mileage, as both cars are still near 20mph hyway
It finally tells us that rear end ratio are meaningless without knowing the total ratio!

If you want a quick way to decide which is best for you. Look at HP used at any speed. that will tell you the comparitive acceleration of two vehicles (assuming the same weight )
HP is an equivilant measure of torque through the gears at the rear wheels at any vehicle speed. its impossible to argue this point, becuase its true. If you understand the big picture, you wont need to argue it either!

MK

 

Yes, it will feel different, as you "could" have a quicker 1st gear, but that depends on traction , HP conditions, skill , etc) however after that, the "feel" will be that you are shifting more at lower speeds for each gear. your not going to feel any difference in most speed ranges, but it may perceive to be different as you are in each gear a shorter time, even though the speeds are proportionally lower. due to the trade offs, a G meter wouldnt notice much average difference over certain speed ranges

so, yes, its kind of cool going through 3 gears to 50mph around town, (ive spent lots of time in my 79 racing and street driving as well as racing Anderson's, and Fans 500+ hp race cars, but on the race track, and depending on the track, the real effects are seen. it can hurt you some places and help you in others. again, gears dont give hp, they only optimize at what speed ranges the max hp can be applied.
In fact, if your application stayed the same, or the track you visited stayed the same, as you grew in HP with mods, you would go from 2.2 to 2.75 and back to 2.2 to optimize the hp available to the ground!

"feel" is subjective to many things

Mk

 

Viper (near mark andersons rear wheel hp) and GT3RSR.

Hmmm, what would you need to do to have the 911 have the exact acceleration rate at any speed??? (keep in mind the porsche does have lesshp, but these are the closest curves i could find. so, in your miind, shift up the GT3curve, so i dont have to find a 438rwhp viper curve!)

ANSWER: close ratio gear box! that would give the 911 the same HP over any speed and thus the same acceleration rate at any speed. (and also same torque at the rear wheels through the gear boxes)

All this, even though the Gt3 porsche has near 1/2 of the engine torque of the viper!!

Glen is right, a=F/m..... but at the rear wheels through the gear box!

MK

 

Mark define "close ratio gearbox" and I believe you end up with more gears between 0-150 mph . And explain away how the larger jump to 5th gear is OK with the 2:20 box. In fact perhaps the "best" gear box for open road racers none drag racers would be a euro Layshaft gear 1.4545 with a USA 2:20 final drive now you get a taller first 8.28, taller 2nd 5.526,3rd at 3.98,4th at 2.9788 and 5th of course is still 2.20 ! but the nice thing is that the gap between 4-5th and resultant RPM drop is smaller than the conventional USA 2:20 which goes from a 3.218 4th to 2:20 . Shift at 6,500 and the special box drops about 1,755 RPM where the normal 2:20 drops about 2080 RPM to 4,420 . The "sweet spot" as some refer to is about 5,500 rpm to 6,500 for a slightly tweaked GT headers X adj fuel high flow exhaust with maximum HP at 6,000 rpm drop back to 4,400 Rpm and RWHp drops to about 260 down from the peak of about 320 rwhp or about 80 % . Perhaps part of what skews the perception is that the 928 engine tends to fall off on horsepower at higher RPM my poor old very brown 1980 actually makes peak horsepower at 5250 RPM and at 6200 has LOST about 20% ! the sweet spot for that puppy is 4,500-6,000 where it maxes out at 198 Rwhp with about 185-198-185 as the curve So the more time I can spend near 5250 the better to maximize horsepower. Spinning the very brown over 6,200 makes little more than noise ! The final iteration of the mix and match is the 2.7272 gears with the USA layshaft 1.5714 (as Shane has) and you get the stump pulling 11.09 first 7.42 second 5.74 3rd 3.98 4th and of course the 2.7272 5th ...Then the true "custom" ratio of 3.09 (Dr Mohr) in his GTS has the layshaft ratio of the Euro as I recall so something like a 11.63 first ! had they used a USA S-4 layshaft gear it becomes a 12.56 first. The reatively high torque of the 928 engines especially the stroker engines and flatness of the curve penalizes you less when you fall down out of the "sweet spot" than say it would with an S-2000 Honda but you still pay a price. The more gears you have between 0-150 the quicker you get to the sweet spot and smaller rpm drops between gears helps maximise the time you can spend there.

 

Jim, don't forget a 2.7272 r+p in an 83-84 US box gives you the poor man's 3.09s. The ratios are only off by about 0.01 in 1st-4th. The only real difference is 5th.

 

Actually, just "more" isnt better, especially to 150mph. sure, a 2.73 or 2.75 will end up shifting at 130mph into 5th, and besides the advantage in ONLY 1st gear, the spacing is the same, and there are trade offs along the way. Think HP/seconds and you get a clear picture. we have gone over this before. the charts are clear and you can see, that depending on your target speed, a 2.2 or a 2.75 maybe the best choise. So, to answer your question, Close ratio means not more gears, but gears closer together. a porsche GT3cup car will have 5 gears down the front straight just as mark anderson has with a 2.75, however, the cup car would be at redline in 5th, while mark would be chugging along at rpms a fraction of his max HP. Its all about maximizing time you spend near max HP. a close ratio gear box of a gt3 cup car has the effect of rasising the average hp to the ground by over 8%, which is significant.
now, take that race from 150 to 175 or 180mph, the 2.2 gets killed for one reasons. one, the 2.2 vs the 2.75 gives the 2.2 much less hp to use from 150hp onward. up to 155mph, the 2.2 has a significant advantage from the point the 2.75 shifted into 5th at 130mph. the 2.75 now is operating at signicantly less HP to the rear wheels for the longest duration of the contest, and at a disadvantage of 2.75 vs a 4th gear ratio of 3.2:1. before that, every shift has been a series of trade offs. (besides 1st) all simulations work out to be very close when comparing a 2.75 to a 2.2 to 115mph trap speed in a 1/4, with the advantage going to the 2.75 due to only a jump with first. take it to 150-5mph, and the 2.2 using only up to 4th, is a clear victor.
The cup car is like having an extra gear after our 2nd gear and before 3rd. besides that, there is not much diff. 1st gear is still like ours at 55mph, 2nd also very close, but after that, a cup car 3rd gear between 85 and 118mph gives the extra time at near max HP.

now, after 155mph, sure the 2.2 is useless for all racing ,except open road racing. a 3.09 on a 2.2 box, would allow for 160mph top speed, and no overdrive. sure, for track racing, 1st would be totally uselsess, and you have no 5th. so, for road racing, there would effectively no difference. actually, the differece of the gears would be a slight disadvantage, but its slight (like the new 4th (5th) being 3.09 vs3.2 (4th) of the stock 2.2)

remember the 3.09 comparison with an S4, all gears were basically the same except for a sub 1st gear of 12.5:1 as you pointed out. were your gears closer together?? no, the gear spacing is still in the .7/1.4 range. sure you added a gear in the sub 1st, (3.09 sub 1st gear) and that did theoretically give an advantage. I doubt in real life you could apply the hp/torque to the wheels in 1st to take advantage of it, but in theory, with no difference in wheel spin, sure, it gets the car out to a head start to the effect of 20% more ave HP and effectively torque through the gear box, to the ground up to 39mph! (not the 12.5:1/8.5:1 would point to)

sure, the range of operation of the 4.5s and the 4.7s seem to fall around 5200rpm, where max hp is. so, with our gears, its a pretty clear 4500 to 6000rpm range, maybe even a little lower. a close ratio gear box would allow you to shift even closer around 5200rpm. wouldnt it be great to have a 1000rpm drop where you shift at 5500rpm and end up at 4500rpm . you would max your hp to the wheels and thus maximize the torque through the gear box to the rear wheels!

so, i agree with what you say at the end. staying at as close to max hp for as much of the time as possible, will yield the best acceleration over the speed range. close ratios help you do this.

Mk

 

a 2.73 on a '84 2.22 box gets you to the sub 1st , 44mph useless for road racing , and then the next 3 gears are even TALLER than the stock 2.2
stock 2.2:
55mph 1st
85mph 2nd
118mph 3rd

vs the 2.73 on a 2.22 box resulting of
44mph first, (useless for road racing)
65mph (taller than 1st )
91mph (taller than 2nd)
120mph (taller than 3rd)

this changes to 3 gears that are actuallly taller than the stock 2.2 now,

in actuallity, for road racing, looking at gear for gear, as i rarely use 1st except in extreme situations. so, the real comparison is 65 vs 85mph in 2nd, 3rd to 91mph instead of to 85mph and then 3rd close to 120mph for both.

interesting comparison. It would hurt more than help, at laguna, i can think of several curves and straights where it would be a problem. as it is now, im between gears where most turns are just too fast to downshift to 3rd, but im still a little low in the rpms out of those turns. this change above would make it worse in most all of the turns at laguna, especially at the most important turn, turn 6 where a taller 3rd for most of the time, going up a long hill would probably kill 1 second of lap time.

of all the gear boxes racers use, why is it the most common spread is almost identical to the 2.2 box ratios up to 155mph?? (besides the GT3 cup car)
55mph, 85mph and near 120mph for 2nd through 3rd is pretty effective.
any changes, at best is a rounding error.


Mk

 

If your car is a daily driver, one place where you'll see a difference is in traffic jams/stop and go driving. With my '82 2.7 5 spd, I could "idle" in first gear and get a comfortable 'creep'. With my '88 5 spd 2.2, first will 'lug' and second is to fast. Not exactly a great reason to change from one to the other....just an observation. The differences in power between the two cars makes any other comparison I'd make meaningless but when I'm constantly operating the clutch in a traffic jam, the 2.7 looks more attractive.

Jim

 

look at 98 911 PET and there are 3 differents stock 3 rd gear ratios available 35:23, 38:27,35:33 plus 3 different 4th gears 41:33, 36:29, 38:34 , then 5th 42:41,33:32 and these are just SOME of the factory ratios. Early 911s you can stack he 3-5 th gear sets just about anyway you wish Porsche "racing" suggestions listed recommended gear ratios depending on the type of track which brings me back to the comments about what gears Mark Kibort is racing AGAINST in other cars ....they could be anything ! Mark sometimes you are like a guy who only owns a 5 lb sledge hammer maybe a 10 lb would be better but all you have is a 5 lb so you just hit it twice... it works for you. But trust me on this you could benefit from being able to use more than 2 or 3 gears at a track. Unfortunately we have few options with the 928 transmission other than the 11:30 (2.7272) ring and pinion , 15:33 ( 2.20) or 11:29 (2.6363, the 89 5 spd not GT) and the chioce of two layshaft ratios which are part of gears 1-4 ratios select a 1.4545 or 1.5714.