89dxhunchback

Well, I have a DX tranny, and I'm going to be pulling the motor to change the clutch... While I'm at it, I was thinking I could/should change over to an SI tranny, but really the DX isn't that bad...

One dude told me the HF was the perfect turbo tranny ( I highly doubt it ), just wondering what everyone thinks about what tranny is the best for turbo hondas..

ZC ( equal lengh axles, but geared Very low )
Si ( direct swap, but geared pretty low too )
DX ( Already have one, still seems to be geared low, but the gears good by pretty quick )
HF ( VERY CHEAP !!, geared high enough to do like 190mph !!!

My goal is to have the car run 13.50@100+mph with DR's, and full street trim on about 13psi, but still not be tapping the redline at 110mph...

Off topic, but does anyone know appox. how fast 5,400rpms is on a DX tranny in 5th ? ( speedo cable = broke )

tgreaves

This has been argued for along time now.. 2 things to look at..

The Si tranny will allow you to rev quicker thus get you down the line faster..

The Dx tranny will allow you to stay in boost longer..

As far as the b-series trannies go everyone seems to agree that the gsr tranny is the best for boost and it has close ratios to the Si tranny.. Im doing a boosted mini-me right now and im going with the Si tranny..

Stay away from the Hf tranny.. They are geared way to high for racing..

tgreaves

Forgot to add.. Ill go out this weekend and run my mini-me with the dx tranny up to 5400 and let you know what the speed is..

Machine1

We're using the DX tranny on a D15B2 and it's run a 13.1 at 103. Thinking about running the Si tranny just to see what difference it would make.

rainmanef

hey let me know how the mini-me turbo turns out cause I'm in the process of piecing together a turbo kit for my mini-me.

89dxhunchback

Thanx for the input guys...

tgreaves

Let me know what et difference you do when you do try the si tranny..

dr_latino999

5400 will be posting around 105+, at 4100rpm I am cruising at 90 mph.

yellowcrx1991

Heres your rpm/speed calculator.

http://crx.honda-perf.org/math/index.html


I'm a little lost on this whole transmission debate. Doesn't everyone consider the SI tranny to be superior to the others(except the hybrid) for an NA engine? How does this change just because you add a turbo. Sure, you'll stay in boost longer, but what for, once you hit full boost, theres no need for it.

I could understand if you wanted a longer gear for top speed.

tgreaves

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by yellowcrx1991 &raquo;</TD></TR><TR><TD CLASS="quote">I'm a little lost on this whole transmission debate. Doesn't everyone consider the SI tranny to be superior to the others(except the hybrid) for an NA engine? How does this change just because you add a turbo. Sure, you'll stay in boost longer, but what for, once you hit full boost, theres no need for it.

I could understand if you wanted a longer gear for top speed.
</TD></TR></TABLE>

Well if you stay in the gear longer then your putting power to the wheels longer.. For a NA setup you want the si tranny for its low gearing..

When you have a turbo setup you fall below the boost threshold when you shift so if you stay in gear and keep it floored then you sitting at max boost for longer.. Thats why automatic trannies are great for turbo since you never loose a load against the motor so you always stay in boost.. Even though I would never own a damn slushbox they are good for FI applications..

89dxhunchback

13 psi with low compression... Hell I've taken it to 16psi on pump gas, but I never go above 13 on purpose... I only run it at about 10psi right now, b/c anymore and the clutch goes "bye bye"...

Lord Quaalard

190 MPH, we all know that is suicidal in a CRX.
*shivers*

tgreaves

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lord Quaalard &raquo;</TD></TR><TR><TD CLASS="quote">190 MPH, we all know that is suicidal in a CRX.
*shivers*</TD></TR></TABLE>

Naaaa.. Just get really good low profile tires.. Lower your car like and inch of the ground.. And grow really big *****..

civbeater90

go with the si tranny-my boy had the dx and si tranny on his greddy powered zc.
si tranny=faster

tgreaves

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civbeater90 &raquo;</TD></TR><TR><TD CLASS="quote">go with the si tranny-my boy had the dx and si tranny on his greddy powered zc.
si tranny=faster</TD></TR></TABLE>

Greddy powered, you mean it had a greddy turbo kit on it.. Did he take it to the track with both trannies.. If so what was the et and speed difference between them..

civbeater90

yes greddy turbo-never got slips for it but street racing the si was faster.dx jus had a longer 5th gear.

Bontke

Another way to look at this is where the engine starts making power. If the turbo start spooling before 3K then most tranys will work. IF the turbo kickins in at 4.5K And above them you probably want a trans that is closer geared keeping the turbo in boost. Most turbos for D-series seem to spool up by 3K. The engine will make much more torque at this level. The Si seems to be geared close to make more torque at lower RPM. IF the turbo is doing this them why get an SI? But you could also look at it as having even more torque when adding an Si trans, then you have to consider traction issues. Too much torque from the turbo and torque multiplication from the trans could leave you spinning the tires on the street and at the track with out proper tires. Best I can say is see what others have experienced and see what boost level and power they are making.

yellowcrx1991

Maybe this should have been posted in the FI forums. Too many theroies floating around, me thinks.

Turbo Dan

i have a turbo zc with a tiny mitsu turbo running 10-12psi
i KNOW i would be able to shave a lot of time off my 1/4 mile with a si tranny.
the dx tranny is killing me.
basically first and second gears of the dx are alright, but 3rd 4th and 5th are horribly long, even with boost.
im switching to an si tranny in the summer time

tgreaves

Generally it is better to go with a lower final drive for boost.. But in the case of dx vs si.. I would take the si because of its 4.25 final drive.. Alot of people with b series stuff go with a higher final drive like in the 4.90 range.. This is a case where the b-series gsr tranny with a final of I think 4.25 would be better then a 4.90 range final..

xci_ed6

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Naaaa.. Just get really good low profile tires.. Lower your car like and inch of the ground.. And grow really big *****..


</TD></TR></TABLE>

Top out your DX trans and then say that. I bet you won't.


Modified by krustindumm at 9:36 AM 1/28/2004

tgreaves

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

Top out your DX trans and then say that. I bet you won't.


Modified by krustindumm at 9:36 AM 1/28/2004</TD></TR></TABLE>

??? Dont really understand what you mean..

tgreaves

At 7k in 5th gear with the hf tranny youll be going 231 mph..

xci_ed6

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

??? Dont really understand what you mean..</TD></TR></TABLE>

It is scarry. Short wheel base, light weight. 150 er 160 er whatever it is, is scarry. One hell of an adrenaline rush, but I will never do it again.

tgreaves

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

It is scarry. Short wheel base, light weight. 150 er 160 er whatever it is, is scarry. One hell of an adrenaline rush, but I will never do it again.</TD></TR></TABLE>

Ahhh.. Hopefully ill get up to some good speeds when I put my boosted type-r motor in my crx..