ok so ive heard/learned that a trap speed shows the power of the car. so it's somewhat safe to say that a nice trap speed with slower time (than normal) will show a strong car, and a low time with low trap will show a good driver... am i on the right track so far?

so anyway i just changed my tranny from an f22 to an h22 (i have an h22 engine). with the f22 tranny, i ran 15.1@93 with wheel hop (2.3 60'). i think a trap of 93 is capable of 14's with a better launch. my question is now that i have an h22 tranny, the acceleration is obviously gonna be better due to its short gear ratios and how im able to stay right in the power band of the h22. so if i run again, my times should be better...but the question is will my trap be higher?

 

it depends....

trap speed does show power to weight. cars of the same weight, one trappin 130 compared to one doing 125..the other car should have more power provided they both have same gearing and tire/etc

running a 13.5 at 106mph shows the car has power but it isnt using all of it on the first 1/8 mile and launch. or it might not have the proper gear ratios. his 60 foot might be around 2.0 lets say and his driving/shifting as average/decent.

now take that same car, add the right gear and set it up to launch hard and use all that power off the line and power thru the 1/8 mile as fast as possible in search of lower ET's. that car might now crack a 1.75 60 foot and run 12.6 at 106mph. he is being more efficient at using his power.


in your case, your changing tranny ratios with effects overall gear ratios. your first run could be improved with better launch/tires. wheel hoppin 2.3 60 foot. say u can squeeze that down to 2.1x's... you'll see 14.9's for sure..maybe even 14.8's.

what u need to check tho is what rpm your trapping at..that is, what rpm is your motor turning as you cross the finish line? if your not near your peak hp rpm of your motor then you need more gear (deeper gears or shorter ratios). so that new trans might allow you to run thru more rpms thru the 1/4 mile, thus making acceleration from start to finish alot faster...you could pick up ET's for sure, and could see 1-2 mph depending on how much gear that new trans gives you.


case in point, my camaro with 2.77 final drive ratio gears went 97mph in good weather. i was crossin the line at like 3700rpms or about that in my 1:1 3rd gear. my motor peaks at around 4500rpms...so i needed more gear or shorter tire. i kept same tires and i swapped in 3.27 gears. i now crossed the line at 4100rpms or so and my trap went to 99-100.9 depending on weather. same 60 foots tho, and similar et's tho...the car had the capability of going faster but with the deeper gears, i didnt have the traction so i couldnt use all my power.

 

nice explanation

 

well i dont kno exactly what rpm i was at, but i can guess...i was at 93mph, so that would be 3rd gear. with my old tranny i topped out 3rd at around 105, so im gonna guess i would be at about 6k-6.5k rpm? my redline is about 7400-7500

 

thats what i was thinkin...your alittle low thru the traps. you could use deeper gears. shorter ratio trans should help you out some. just hope its not that much shorter and you start over revving at the end. i cant seem to locate the exact ratios of the h22 trans over the other.

 

the h22 tranny has much shorter gears

the tranny i have now...
M2Y4 - 3.285 - 1.956 - 1.344 - 1.034 - 0.812 - 4.266

my old one...
P2U5 - 3.307 - 1.809 - 1.185 - 0.933 - 0.685 - 4.062

 

oh wow, yes indeed. that should really get u moving. those are much shorter.

hard to say tho how much rpm your gonna gain, what tire size you running? that tranny might give u too much gear with a smaller diameter tire.

 

i got 205/40/17...smaller than stock. so it'll get me movin in that my trap and time will be better or just the time?

 

F22 is the single cam vtec?

 

no i believe its the sohc no vtec. its in the accord ex and the prelude s

 

Well what we noticed from a non vtec trans on a h22 is that the gears were way longer and it always droped out of vtec even shifting at 8500 rpm. With the h22 you should be a little quicker

 

yea i kno...thats exactly why i got the h22 tranny. i used to always end up at liek 4900-5000 after i shifted with the f22 tranny but now im at bout 5500rpm after i shift

 

 

sorry i didnt realize this before...

your only goin thru 3 gears in the 1/4 mile with that old trans. not good. lol you want to go thru the top of your 4th gear thru the 1/4 to get the best results. 4th is usually your 1:1 gear ratio...or close to it.

with the new trans and final drive, you'll be in 4th gear.thats a start...lets see how far in you will be

old trans, lets say you shift at 7500rpm...using those tires
1st should go to 38mph
2nd brings to 71
3rd goes to around 108 theoretically
so your trapping 93 at close to 6400rpms in 3rd

new trans, same tires shift 7500rpms
1st goes up to 37
2nd brings to 62
3rd goes up to 91mph
4th goes to around 118

so you will be shifting into 4th sometime around the 1000 foot mark or so and 94mph is around 6000rpms, so i would think your trap should go up to 95-96 at best. 94-95 is still good gain tho. but you probly could use a deeper final drive..someting around 4.7 final drive with that trans to really get all you can out of your combo as the car sits.

but those gears will be good once you get more power and useable rpm range

but more importantly you probly will be going to 4th gear 6000rpm traps from 3rd gear 6400rpm traps. that should really drop the ET's which is what you ultimately want to accomplish


another case, my buddies 89 Firebird has the same motor as me, same transmission. his motor has more mods tho, but he probly only has 10-15whp more than me, but he weights slightly more than me. my gears is 3.27 and his is 3.70.

from a roll its a dead even race thru 3rd gear, as he traps 99-101 to my 97-98. at the track tho, he gets me by a car or 1.5 cars..13.6x to my 13.90. the gearin off the line KILLS me. he pulls very hard in first and lower part of second with that advantage. gears help

 

I have a 5th gen prelude with an stock tranny and my fuel cut has been raised to 8,000 RPM.
I've noticed, that my 3rd gear can be held to around 96-97 mph. I'll usually hit the limiter when i cross the line, sometimes before though. I recently ran with 23x8.5x15 slicks. My launch rpm was ~7,500 and my burnout wasn't the best, but I managed a 1.987 60ft. My time was 14.333 @95.72 that's with shifting into 4th at 8k. With a trap speed that low it might be better to hold out 3rd and if i need to just shift at the last second so i can be deeper in my powerband. What do you guys think?
-Greg P
P.S. Before I went to slicks I was running 205/50/R16 tires. Would the slicks make my gears longer or shorter. They seem longer.

 

your street tires are about 24 inches in diameter...the slicks are advertised as 23. the taller tire would make your gears seem longer. so the slicks should shorten your gears

but the extra size and rolling resistance from the sticky rubber could slow you down too to make it seem like longer.

if your 3rd can go to 97 and your trappin 95-96..then hold 3rd till you cross the line... you lose time shifting to 4th before the traps... just make sure you hit the top of your power band on the 1-2 2-3 shifts to get as far as you can in those gears to prevent hittin the limiter just before the traps.
else you should try a 24inch slick or 23.5 if they make that

 

thanks for the great info...

how the hell did u figure out the approx. max speed of each gear? what equation is there?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Orr89rocz &raquo;</TD></TR><TR><TD CLASS="quote">your street tires are about 24 inches in diameter...the slicks are advertised as 23. the taller tire would make your gears seem longer. so the slicks should shorten your gears

but the extra size and rolling resistance from the sticky rubber could slow you down too to make it seem like longer.

if your 3rd can go to 97 and your trappin 95-96..then hold 3rd till you cross the line... you lose time shifting to 4th before the traps... just make sure you hit the top of your power band on the 1-2 2-3 shifts to get as far as you can in those gears to prevent hittin the limiter just before the traps.
else you should try a 24inch slick or 23.5 if they make that</TD></TR></TABLE>
Thanks for the info. Most preludes make their power at 8,000 rpm on the tach, so that's where I usually shift. question: would it be better to shift were your peak power occurs or hold out every gear to fuel cut (~300 rpm more in my case) to get quicker times. I think this would depend on if your power drops more quickly at fuel cut then the rpm you would be at when you shift. If your power drops slowly after you hit your peak, then it would be beneficial to hold it out so when you shift your higher in your powerband. Let's compare: 1. You hold your gear to fuel cut and loose 7hp. 2. You shift at your peak, but lose about 15 due to lower rpm. It seems to me you'd be better off holding every gear to fuel cut. But I am no expert.

 

I just want to clear something up. I've always heard that to get a 13.9 you have to trap 100mph, is that true? Every 13.9 timeslip i've seen has been at 100 or over.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by precisionelite &raquo;</TD></TR><TR><TD CLASS="quote">I just want to clear something up. I've always heard that to get a 13.9 you have to trap 100mph, is that true? Every 13.9 timeslip i've seen has been at 100 or over.</TD></TR></TABLE>

negative... its all in the 60 foot. the faster you get off the line, the quicker you go obviously. but your cars have better top end than lowend. if you can go 1.9s on the 60 or even 1.8s on slicks or w/e, then you can easily see 13.9s with 97mph traps or even abit less. i seen a few cars go 13's with 94-95mph traps. killer 60 foots tho. S2000's are hittin 13.7-13.8s at 100mph. LT1 auto fbodies can do 13.8s at 98-99. 350z's do 13.8s at 100 as well. all with around 2.0 60 foots, so 100 is a good startin point, but if you get off the line faster--in those 1.9's or better, you'll see deeper 13's at high 90s for sure

my car does 13.7s at 97...1.80 flat 60 foot. my car has good low end but nothin on top. it should go 13.6s at similar trap with few more tweaks


as far as shifting goes, it varies...most manual cars i known like to shift a few hundred rpms past peak power. so if your at 8 grand, try 8300 or 8500. that extra rpm helps drop the next gear higher in the powerband, and thus you are suppose to be quicker. your just gonna have to try it out. my auto car seems to like to shift beyond peak hp. cuz i think peak is 4500, but it goes to 5000 pretty strong. i'll find out saturday when i dyno it.


as far as information, there are tons of calculators/equations on the net. the one i like to use the most for general gear/tire combinations and mph is this one
http://www.speedworldmotorplex.com/calc.htm

its 1/4mile is pretty close for my car as well as a few others...rough estimate

theres a great honda one i found earlier...
http://www.fatboyraceworks.com/gears/

alot of trannies in there but i didnt see the h22 one?

 

I loaded the H22 gear ratios manually
Here's what I got
Slicks (23'' diameter)..........Street Tires 205/50/16
1rst Gear: 39.08 MPH................................40.9
2nd Gear: 65.63 MPH................................68.68
3rd Gear: 95.51 MPH.................................99.96
4th Gear: 124.15 MPH...............................129.92

Looks like I might need to shift into 4th after all. I'll do it at fuel cut though

 

http://www.fatboyraceworks.com...are=1

so it looks like ill be shifting into 4th gear right before the end. am i better off holding out 3rd gear?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 95hprelude &raquo;</TD></TR><TR><TD CLASS="quote">http://www.fatboyraceworks.com...are=1

so it looks like ill be shifting into 4th gear right before the end. am i better off holding out 3rd gear? </TD></TR></TABLE>
The only way your gonna know is by trying it out for yourself. I will tell you that when I ran my 14.315@96.62 I powershifted into 4th.
Check out your transmissions with an 8,000 RPM Redline
http://www.fatboyraceworks.com...are=1

 

i think its best you try... if you shift fast, 4th might be quicker... else third might be it

 

S2000's are hittin 13.7-13.8s at 100mph. LT1 auto fbodies can do 13.8s at 98-99. 350z's do 13.8s at 100 as well. all with around 2.0 60 foots, so 100 is a good startin point, but if you get off the line faster--in those 1.9's or better, you'll see deeper 13's at high 90s for sure.

The only thing with these cars are that they are all rwd. Rwd cars tend to run a bit slower in the 1/4 than fwd cars with similar setups.