GT vs. Spec-B

[rallysquirrel]

I beg to differ.

The curve you see is wheel torque. Torque curve tells all. Gearing will affect what speed you can get to.

 

In 6sp

If you want to get to 45mph then 1->2 in 6sp is best.

If your desired limit is over 45 and to about 70mph then go 1->3.

 

So for autox or rallyX you'd use 1st and 2nd gears. Since you'll actually spend time there.

If you're drag racing then skip the 2nd gear.

 

From my testing going from top of 1st and switching into 3rd gear puts me at about 2800-2900 rpm in 3rd gear, netting me about 210 wheel torque at the new shift point (see graph).

From my experience (seat of pants and experience) that graph is pretty much spot on, but won't be able to PROVE it until I get my car dynoed.

 

Hope that will put things to rest.

 

Jan

[Spec B]

^^ Considering you drive the car daily I totally believe you even though it makes no logical sense to me..

 

i think of it like this:

 

Although while in 3rd you will be at a higher torque you are still way down low in 3rd gear and I can;t imagine it pulling harder than the high end of 2nd gear..

[rallysquirrel]

..but if you have to shift again from 2nd to 3rd you'll lose precious moments (tenths of seconds ), because 2nd gear will only get you to 55 mph max.

 

Only thing I'm lacking when switching to 3rd that way is whp.

[ilh]

I beg to differ.

The curve you see is wheel torque. Torque curve tells all. Gearing will affect what speed you can get to.

Wrong. Wheel torque is affected by gearing. Do you really believe you can exert the same torque on the wheels in 1st gear and 5th gear at a given RPM at a given crank torque?

[Spec B]

..but if you have to shift again from 2nd to 3rd you'll lose precious moments (tenths of seconds ), because 2nd gear will only get you to 45-48mph max.

 

Only thing I'm lacking when switching to 3rd that way is whp.

 

I am going to try this on my buddies STI...

[rallysquirrel]

You're right about the gearing affecting wtq. No you cannot exert the same torque a the wheels in all gears. Engine will make same torque but because of the gear ratios you'll have far less torque at the wheels in higher gears.

 

Most dyno pulls are done in 3rd gear, correct? and this one was probably as well (I'm assuming).

 

I was still referring to the acceleration of a specB and accelerating to highway speeds.

 

next time i'll have to be more specific, before I've got to explain myself completely. I should've specified accelerating to what speed, because that's going to determine what gear you're gonna choose based on torque characteristics.

[Fat Charlie]

I was under the assumption that the '07's 6th gear was taller, but if it doesn't, than I definitely don't rank it as high an upgrade that I did before. And I agree closer ratios would be basically pointless.

 

I need the wagon, so I'm stuck in 05 for as long as SOA has their heads stuck up their asses. Looking at the numbers that Spec B posted, though, the 6 speed is a waste of time. My 5 speed is great and I love it. It matches the engine very well and I love the acceleration. There's enough power there for another gear on top, though. If a really low 2nd gear helps you on the autocross, then that's great. If a really low 2nd gear is best skipped on the way up to speed, then to me it's just a 5 speed with a bad shift pattern. I don't want a top gear that happens to be higher than what I've got, I want an an actual higher gear.

[wsf0817]

I've seen the SAME car dyno +/- 8 HP on the SAME dyno on the SAME day.

 

Dynos are subjective. 10% from different cars is not much to rest your hat on. Production variances, weather, etc....

[rallysquirrel]

I don't usually skip 2nd gear cause I usually try and accelerate slowly so not to eat up too much gas and shift at 4k rpm at most. If I however want all out acceleration, I skip 2nd gear.

[Ezay2thaPeezay]

Dynos are subjective. 10% from different cars is not much to rest your hat on. Production variances, weather, etc....

Word.

[wukindada]

Production variation is all but non existant anymore......take 100 2.5l off the Subaru assembly line.

 

They will all be within 5hp of each other!!

[NSFW]

(nevermind)

[Vimy101]

My 5 speed is great and I love it. It matches the engine very well and I love the acceleration. There's enough power there for another gear on top, though. If a really low 2nd gear helps you on the autocross, then that's great. If a really low 2nd gear is best skipped on the way up to speed, then to me it's just a 5 speed with a bad shift pattern. I don't want a top gear that happens to be higher than what I've got, I want an an actual higher gear.

 

If I do an "easy" hard pull to 75mph (1-2-3) I end up having to double clutch and skip a gear to 5th. When I do a "lazy" hard pull (1-2-3-4) I've arrive at cruise and then shift to 5th.

 

With the 6MT, I'd be skipping gears all the time. With the turbo boxer, 6 gears just seems redundant. If it is a more robust unit then excellent but it does come with a weight penalty. I also believe that for some motoring situations having a more exact gear would be cool. But even then, the boxer with the 5MT never seems to be at odds because once that turbo kicks in you have all the available power you want.

 

At most, comparing 6MT to 5MT in the Spec.B mechanical performance wise is almost moot. The weight penalty, however, remains.

[rallysquirrel]

I agree that you don't need 6 gears. However on the highway I like being able to cruise at lower rpms in 6th. I only wish it was even taller than it is.

 

Around town/local roads I usually drive 1-2-4-6

 

A customer is never happy, right.

[Fat Charlie]

With the 6MT, I'd be skipping gears all the time. With the turbo boxer, 6 gears just seems redundant.

 

Ah, but I don't want the 6MT. With the 2.5 turbo, closer gear ratios aren't even redundant- they're wasteful. I don't want Subaru's 6 speed, I want the right 6 speeds. The 5MT is terriffic until I have to loaf around on the highway without any hope of needing acceleration. I want a 6th gear that is actually the next step up from my current 5th gear.

 

You skip 4th on an easy pull? 2nd gets me to 60, so I skip 3rd, too. 75mph notwithstanding, what this car needs for the highway is a gear that you shouldn't go to from 2nd. It'll mean downshifting for passes, but if I shied from that I'd have an automatic.

 

I'll be looking at the next generation wagon. I'll check the web to see if they've brought the manual back to the US. If they have, I'll test drive it and see if it's the right manual. The right one has a 6th gear that Air Force guys would call "supercruise."

[rallysquirrel]

So far I've only come across tall gears like Fat Charlie is refering to on "The Big 3" car and trucks.

[CreoSTi]

IIRC, 6th in my old Audi S4 wasn't that much of an overdrive gear either...

 

-Mike-

[Vimy101]

Ah, but I don't want the 6MT. With the 2.5 turbo, closer gear ratios aren't even redundant- they're wasteful. I don't want Subaru's 6 speed, I want the right 6 speeds. The 5MT is terriffic until I have to loaf around on the highway without any hope of needing acceleration. I want a 6th gear that is actually the next step up from my current 5th gear.

 

You skip 4th on an easy pull? 2nd gets me to 60, so I skip 3rd, too. 75mph notwithstanding, what this car needs for the highway is a gear that you shouldn't go to from 2nd. It'll mean downshifting for passes, but if I shied from that I'd have an automatic.

 

I'll be looking at the next generation wagon. I'll check the web to see if they've brought the manual back to the US. If they have, I'll test drive it and see if it's the right manual. The right one has a 6th gear that Air Force guys would call "supercruise."

 

An easy way of upping your final drive a bit would be to go to 18" wheels or correspondingly taller tires on your 17s. You could gain a few per cent right there. It does seem to make a difference on the Spec.B mileage compared to the LGT.

[NSFW]

An easy way of upping your final drive a bit would be to go to 18" wheels or correspondingly taller tires on your 17s. You could gain a few per cent right there. It does seem to make a difference on the Spec.B mileage compared to the LGT.

 

In light of the spec B ratios posted earlier I think it would be a mistake to assume that any mileage difference comes from the tires alone:

 

http://legacygt.com/forums/showpost.php?p=892761&postcount=47

 

Spec B in 6th gear: .707 * 3.454 = 2.44 overall ratio

GT in 5th: .78 * 3.9 = 3.04 overall

 

That's quite a difference. I'll let someone else do the rest of the math (2nd and 3rd would be most interesting).

[Vimy101]

In light of the spec B ratios posted earlier I think it would be a mistake to assume that any mileage difference comes from the tires alone:

 

http://legacygt.com/forums/showpost.php?p=892761&postcount=47

 

Spec B in 6th gear: .707 * 3.454 = 2.44 overall ratio

GT in 5th: .78 * 3.9 = 3.04 overall

 

That's quite a difference. I'll let someone else do the rest of the math (2nd and 3rd would be most interesting).

 

The tire size does make a difference in my 06 Spec.B experience.

[ilh]

Spec B in 6th gear: .707 * 3.454 = 2.44 overall ratio

GT in 5th: .78 * 3.9 = 3.04 overall

If you factor in the tire diameter difference (24.6/25.6), that puts the SpecB even lower with respect to the LGT at 0.96*2.44 = 2.34. That's 30% lower vs. the LGT.

 

Does the 6MT SpecB really cruise at 75mph at ~2400rpm as compared to the LGT at ~3100rpm?

[rallysquirrel]

At 80 mph I'm at 3,000 rpm.

[geddyup]

better off to get a euro car for the spec b surcharge

[PhilT]

better off to get a euro car for the spec b surcharge

 

Let me guess, like a Volvo

[ilh]

At 80 mph I'm at 3,000 rpm.

Then something is wrong with those gear and/or final drive ratios. At 80mph I would be around 3300-3400, which says the 07 SpecB's overall ratio including larger tires is only about 10-14% smaller, not 30%.