Advantages & Disadvantages of Turbo w/ B15 transmission.

[RaggaMuffin VVL]

I just hear everyone saying B15 for N/A and p11 for boost.
I know the shorter the better acceleration...
Now for DD the shorter gears shouldn't be that bad since the turbo only builds boost @ WOT disadvantages


what are your opinions on powerbands, acceleration, max MPH...etc..?

[STRATTON]

put it this way, i run a p11 tranny on my boosted nx. first and second are none exsistant at wot, i wouldnt want to imagine a b15 tranny in my car.

get a p11 or stick with a reg b13 tranny.

stratton.

[Johnny wangwang]

Are the B15's 1st and second even shorter then the B13's?

I dont know about yall. But the B13's ratios work perfect for me...

[RedDragun]

B13's too short for my tastes. I am out of gear in 4th at the end of the track. Obviously I could go with bigger slicks or a higher rev limit, but a stouter and better-suited-to-my-needs geared transmission is the way to go with turbo cars.

[RaggaMuffin VVL]

But wouldn't the shorter gears be suited for bigger turbo applications? like a gt35r.

I'm sure most of you are running t25's and t28's, so you'll be roasting tires no matter what.

Well, the reason I took interest in the B15 trasmission for bigger turbo application is because of this Vid http://videos.streetfire.net/video/n...rbo_166422.htm,
plus many Hondas use the same type of shorter gears ratios in turbo application and had many success http://www.autocrossing.com/cgi-bin/gearcalc.cgi

What do you guys think?

[Johnny wangwang]

Our stock 4th gear gets me up to 120 right at redline....

I have also maxxed out my 50lbers so I know im making power. Im also running a bigger turbo then then a T28 but it has a broader power band since it starts to spool at 3k (ive got 7lbs by 3100) and is finished at right before 4k. But traction in first is my only issue really. 2nd gear isnt worthless in my car...

Where does the third and fourth gear redline MPH wise in the P11 and b15?

[Coheed]

On my p11 I hit 97.5mph in 3rd at 7500rpm. In 4th it is 130 or so easy. I like the p11, but the b13 tranny will walk on it if you don't have enough power. I have around 400 or so and 4th is a ton of fun, just not as quickly passed like the other trannys.

All in all I think the p11 tranny will suit the car nicely in the 1/4 when I start making over 500whp or trapping over 125mph.

[Johnny wangwang]

Heh I love just putting my car in 4th at 45mph and just hitting it! 4th gear for me is like second for other people. For a street car that doesnt see much track the B13 tranny is A ok! 45-120 goes by so quick its crazy!

[Forced Compression]

b13 tranny is fine for a street car, b15 gears are nice!!!! i love short gears! but my next project is going to utilize a spec v transmission

[Payu]

I would say it depends on you engine setup if you have a engine that keeps making power after 8,000 rpm also have a laggy turbo then you can take advantage of the of the shorter gears because the car will accelerate quicker an you can always stay on your power band. The car that you see on the video he shifts the car at 8,500 rpms so you do the math...

[RaggaMuffin VVL]

Originally Posted by Johnny wangwang

Where does the third and fourth gear redline MPH wise in the P11 and b15?

according to Autocrossing.com using these gears http://www.brentroad.com/photos/00360628.jpg
B15 transmission
Gear/ ShiftRPM/ Speed @ 7200 RPM
1st/ N/A/ 33.9
2nd/ 4223/ 57.8
3rd/ 4736/ 87.8
4th/ 5184/ 122.0
5th/ 5699/ 154.1
RPM in top gear at 75 mph: 3504

P11 transmission
Gear/ ShiftRPM/ Speed @ 7200 RPM
1st/ N/A/ 36.0
2nd/ 4223/ 61.4
3rd/ 4736/93.3
4th/ 5184/ 129.6
5th/ 5878/ 158.8
RPM in top gear at 75 mph: 3401
[**Both cars using a tire diameter in inches of 23.4**] and
87.8 minus 93.3, which is a 5.5mph difference in third and 122 minus 129.6 is a 7.6mph difference.

Originally Posted by Payu

I would say it depends on you engine setup if you have a engine that keeps making power after 8,000 rpm also have a laggy turbo then you can take advantage of the of the shorter gears because the car will accelerate quicker an you can always stay on your power band. The car that you see on the video he shifts the car at 8,500 rpms so you do the math...

I'm planning on building a VE+T with a GT2876r, I wanted to take advantage of the powerband, so after doing some research on Honda-tech, since most ppl use the Gs-R or Type-r transmission with similar gears in fact shorter gears and than the B15 transmission and have plenty of success with them.

[RedDragun]

If you plan on drag racing you wont want anything shorter than a B13 tranny if you are trapping near 120.

[Coheed]

I don't think you wanna be shifting to 5th gear before the end of the quarter. My p11 seems like this with a 205/55r15.
according to the guage rev to 7500:
1st 35
2nd 60+
3rd 97
4th 130+
I never top out 4th gear so I don't know how fast I am going when I bounce the limiter. But it is fast.

[Payu]

If you plan on using big slicks the B15 will benefit for the launch too... again all depend on the powerband of the engine...
You cant compare a B series Honda engine with a SR20VE-T powerband its way different thats why they take advantage of the shorter gears but if you are planning to use a GT2876 I would say that you should use the P11 transmision....

[RaggaMuffin VVL]

Originally Posted by Coheed

I don't think you wanna be shifting to 5th gear before the end of the quarter. My p11 seems like this with a 205/55r15.
according to the guage rev to 7500:
1st 35
2nd 60+
3rd 97
4th 130+
I never top out 4th gear so I don't know how fast I am going when I bounce the limiter. But it is fast.

True, I really want to end the track in fourth.

Originally Posted by Payu

If you plan on using big slicks the B15 will benefit for the launch too... again all depend on the powerband of the engine...
You cant compare a B series Honda engine with a SR20VE-T powerband its way different thats why they take advantage of the shorter gears but if you are planning to use a GT2876 I would say that you should use the P11 transmision....

I'm gonna give the B15 transmission a chance, play with the Boost by gears
if it doesn't work out, i will change to the p11 transmission.