TypeSLO

i'm thinking of changing my LS trans to a 99 Si trans for the shorter gear ratios. i think there will be less load with the Si trans so will there be a significant difference in peak power and my overall powerband? also, any difference in spool time? currently, i'm making just over 400whp and a little over 300ftq with a gt35r. thanks.

TypeSLO

bump?

crowder13

keep the ls or get a gsr, unless u track it all the time.

bigbadboy

keep the LS tranny. its awesome. that tranny is only shorter. i had a GSR tranny on my LS and i didn't like it at all.

Tippyman

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bigbadboy &raquo;</TD></TR><TR><TD CLASS="quote">keep the LS tranny. its awesome. that tranny is only shorter. i had a GSR tranny on my LS and i didn't like it at all.</TD></TR></TABLE>

May I ask why? Shorter gears = faster.

Tippyman

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TypeSLO &raquo;</TD></TR><TR><TD CLASS="quote">i'm thinking of changing my LS trans to a 99 Si trans for the shorter gear ratios. i think there will be less load with the Si trans so will there be a significant difference in peak power and my overall powerband? also, any difference in spool time? currently, i'm making just over 400whp and a little over 300ftq with a gt35r. thanks.</TD></TR></TABLE>

To answer your question, any horsepower gain from switching trannies would be unnoticeable. It'll be faster with an si tranny because of the shorter gearing though. Your power will be the same.

TypeSLO

i'm concerned with the difference in load. won't the turbo spool quicker with more load? and if that's true, wouldn't that affect the overall power band and the spool time? i'm thinking of doing this for track purposes.

blwn95civic

in my opinion, the ls seems to be a faster trans for the street and racing from a rolling start, i say this because usually when ppl race on the streets, they end up doing a high speed and having the long gears = longer gaps between shifts. which will give more time for acceleration

the si trans tho seems to be quicker from a stop because of the lower gears allowing the quicker acceleration

this is just my opinion, i went from the ls to the b16 trans... i kinda wish i woulda waited til my setup was boosted before i switched trans tho... ppl say third gear in a LS is fun with boost

laocivic

keep the LS...Witht he longer gears you'll stay in boost longer!!! b16 gears aren't to great for boost. b16 gears will get you at 5th gear in like 2 seconds

TypeSLO

most of the guys that replied to a post in the drag racing forum prefer the Si trans. i'm not really interested in street racing especially since the car is just ridiculous enough as it is and lacks traction. i'm aiming more directly at track racing (where it should be anyway) running on slicks. i know what you guys are saying but it doesn't answer my question still. i'm looking for a more specific answer on the impact it will have on the powerband and spool time, etc. preferrably a dyno comparison.

bigbadboy

there is none. its just how long or short the gears are thats all. you dont gain power or power band or spool. you can't change that unless you change your motor.

SOHC_MShue

Your just going to have traction issues and have to go into 5th gear at a real low mph.

JaredKaragen

shorter tranny=better butt-dyno response

Chris Tune

match your powerband to the tranny... theres no other way around it.

Tippyman

i thought we had all gotten past the whole "LS or long gear trannies are best for boost, y0!"

shorter gears = better acceleration. period.

The rule of thumb for drag racing, is that you want to be deep into, or top out fourth gear right as you cross the finish line. this way, you have the shortest gears available without having to shift into 5th.

SOHC_MShue

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tippyman &raquo;</TD></TR><TR><TD CLASS="quote">i thought we had all gotten past the whole "LS or long gear trannies are best for boost, y0!"

shorter gears = better acceleration. period.

The rule of thumb for drag racing, is that you want to be deep into, or top out fourth gear right as you cross the finish line. this way, you have the shortest gears available without having to shift into 5th.</TD></TR></TABLE>
a friend of mine had a ls with a b16 trans and i believe it was topping out 4th at a lower mph than he would have trapped at in the 1/4. Taller tires probably would fix that though.

Tippyman

Well, if an LS trans is better for your power level, then go for it. But, not a lot of people are making that kinda power.

SOHC_MShue

I guess a lot of its personal preference too. One of my good friends wont run anything but a b16 tranny on any setup he has

Tippyman

D16 Si trans for me!


Modified by Tippyman at 6:29 PM 9/19/2007

CoreyR

i was running out of gear (4th) a good amount before the traps on a B16 trans with 23" slicks revving to 8500. 114ish letting off. unless your running big slicks or are trapping less than mid teens i wouldnt recommend a B16, and i certainly wouldnt recommend an LS. i think a GSR is the most well rounded tranny.

TheShodan

iTrader: (14)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tippyman &raquo;</TD></TR><TR><TD CLASS="quote">

To answer your question, any horsepower gain from switching trannies would be unnoticeable. It'll be faster with an si tranny because of the shorter gearing though. Your power will be the same.</TD></TR></TABLE>

You're almost right, BUT, I have found that it is the final drive gear ratio in relation to the other gears that help with ACCELERATION, not power. the 4.4 final drive of the USDM B16, B18C, and C5, are actually really good for boost. I had the LS transmission believing the other gearing (and not trusting my own calculations and purpose) and I was truly disappointed. So I created a Cross-transmission for my particular goals. that being said, I have found that with the B18b motor with its lower rpm band, good torque band, and lower flowing head works just fine. Change that to a VTEC head, and you may think otherwise. Staying within the powerband of the engine with a different final drive in and of itself really helps as a torque-multiplier without adding peak power. You don't see it on a dyno with just one gear. You feel that through the acceleration rate of going through ALL of the gears with a different final drive. This is an additional reason why many drag racers in the higher eschelon of racing use higher final drives.. for acceleration. The "staying in boost longer" myth really doesn't apply when there are different uses with different final drives. Considering most of the choices in the U.S., the 4.4 final drive from either the b16, B18c, or C5 do just fine. A 4.2 final drive found in the LS, is good for AN LS. Hell, even older race Evolution drivers use a 4.5 final drive, when the stock is about 3.7.

Hope this helped a tad. Let me know if you need a torque-multiplier chart.

blackeg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CoreyR &raquo;</TD></TR><TR><TD CLASS="quote">i was running out of gear (4th) a good amount before the traps on a B16 trans with 23" slicks revving to 8500. 114ish letting off. unless your running big slicks or are trapping less than mid teens i wouldnt recommend a B16, and i certainly wouldnt recommend an LS. i think a GSR is the most well rounded tranny.</TD></TR></TABLE>

good info. you want to match the trans to the powerband, and if u track it a lot, match it to your tire size, trap speed and rev limit, so you cross the finish high in 4th but not into 5th.

now, ive run an ls tranny on a 300+ hp lsvtec for well over a year now. i liked it on the highway for just 4th gear pulls, but it started to suck real bad especially once i got over 400 hp. i just switched to a gsr trans with lsd and am very happy. the car accelerates faster, and the higher gearing helps out, like if i spin a gear and have to shift, it gets back up into the powerband much quicker than the ls did. really feels like it took a lot of the lag out. also, with the 24.5" slicks and my current rev limit, i should be crossing the finish in the 1/4mile around 8000rpms in 4th gear