hf vs si tranny?

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Periculum

Senior Member
My friend was told that an EW HF tranny and SI tranny were the same. I know the EF trannys have the same number, but are not the same in the slightest when it comes to gearing. Is it the same way with the EWs?


I searched and checked the reference stuff, so i think i looked at all the possibilities.
 

jlicrx

Senior Member
VIP
CRX SPECS (USDM)

1984-1987 DX


Weight - 1819
Displacement - 1488 cc
Valve/Intake - SOHC 12valve/ carb
Compression - 9.2:1
Power - 76@5500
Torque - 84@3500
Redline - 6500 rpm
Gear ratios - 2.38/ 1.76/ 1.18/ 0.85/ 0.71
Final drive ratio - 4.27:1

-----


1984-1987 HF

Weight - 1713
Displacement - 1342 cc
Valve/Intake - SOHC 8valve/ carb
Compression - 10:1
Power - 60@5500
Torque - 73@3500
Redline - 6000 rpm
Gear ratios - 2.92/ 2.03/ 1.44/ 0.89/ 0.65
Final drive ratio - 3.58:1

-----


1985 SI

Weight - 1890 lb
Displacement - 1488 cc
Valve/Intake - SOHC 12valve/ EFI
Compression - 8.7:1
Power - 91@5500
Torque - 93@4500
Redline - 6500 rpm
Gear ratios - 3.30/ 1.99/ 1.35/ 1.00/ 0.79
Final drive ratio - 4.27:1

-----


1986-1987 SI


Weight - 1953 lb
Displacement - 1488 cc
Valve/Intake - SOHC 12valve/ EFI
Compression - 8.7:1
Power - 91@5500
Torque - 93@4500
Redline - 6500 rpm
Gear ratios - 2.92/ 1.76/ 1.19/ 0.87/ 0.71
Final drive ratio - 4.40:1
 

Buff_Hatch

Junior Member
I can tell you first hand that the HF and Si trannies, both 5 speeds, are completely different. In fact, for 88-91, there are 3 different 5 speeds and a 4 speed transmission too.

The 4 speed was found in the STD body style or the 70 HP variant of the engine.

The DX 5 speed was found mated to the 92 HP engine. This had 1-5th gears same as the Si but with a taller final drive.

The Si 5speed was with the 108HP engine and had performance FD, ie, slightly smaller. Probably do about 3500-3800 rpm at 80 MPH in 5th.

Now the HF actually had 2 different versions of 5 speeds. They both had taller
1-5th gears. One has a huge FD, something like a 2.82 and the other had a gigantnormous 2.18 FD.

If you had the HP, you could go about 187 MPH [no joke] in 5th gear running about 6500 rpms... That is why the HF gets about 55 MPG on the highway and 49 MPG city.
 

Periculum

Senior Member
I was wondering about this too. The same buddy of mine had been told that the 84 HF was different from the rest. He is all about the gas mileage on his 30-40 Mi commute every day, so he wants to mate the Si motor he has to an HF tranny. He wants to have the highest fifth, because he also makes trips from Rome,GA to Augusta,GA (~300mi?) Is there any way to fidn which HF tranny was taller?
 

jlicrx

Senior Member
VIP
Periculum said:
I was wondering about this too. The same buddy of mine had been told that the 84 HF was different from the rest. He is all about the gas mileage on his 30-40 Mi commute every day, so he wants to mate the Si motor he has to an HF tranny. He wants to have the highest fifth, because he also makes trips from Rome,GA to Augusta,GA (~300mi?) Is there any way to fidn which HF tranny was taller?
84-87 HF transmissions all have the same gear ratios - see table above
 

Buff_Hatch

Junior Member
Periculum said:
I was wondering about this too. The same buddy of mine had been told that the 84 HF was different from the rest. He is all about the gas mileage on his 30-40 Mi commute every day, so he wants to mate the Si motor he has to an HF tranny. He wants to have the highest fifth, because he also makes trips from Rome,GA to Augusta,GA (~300mi?) Is there any way to fidn which HF tranny was taller?


Well, the 84-87 trannies and NOT the ones to be looking at in the first place. If you have this: 91 CRX as in your sig. then you need to stay with a 90-91 tranny. The 88-89's will work but the flywheel, clutch.. etc, are ALL different.

So, for ease of use, swapping, a '90-'91 will bolt right in with no other mods. As for the difference between the HFs.. Only a complete tear down will reveal the true FD ratio. If you use CARFAX, you could run the VIN and then Call Honda dealership and they can tell you or match it up too.

The high-heared trannies are part of the equation for higher MPG, the motor in the HF had only 65 HP and delivered a strong torque curve at low RPM, about 95 lbs if I recall. The Si only delivered around 80 lbs.

--Good Luck to you.
 

d.b.cooper

Mid-life Crisis Swap
ab slo utely!

Buff_Hatch said:
I can tell you first hand that the HF and Si trannies, both 5 speeds, are completely different. In fact, for 88-91, there are 3 different 5 speeds and a 4 speed transmission too.

The 4 speed was found in the STD body style or the 70 HP variant of the engine.

The DX 5 speed was found mated to the 92 HP engine. This had 1-5th gears same as the Si but with a taller final drive.

The Si 5speed was with the 108HP engine and had performance FD, ie, slightly smaller. Probably do about 3500-3800 rpm at 80 MPH in 5th.

Now the HF actually had 2 different versions of 5 speeds. They both had taller
1-5th gears. One has a huge FD, something like a 2.82 and the other had a gigantnormous 2.18 FD.

If you had the HP, you could go about 187 MPH [no joke] in 5th gear running about 6500 rpms... That is why the HF gets about 55 MPG on the highway and 49 MPG city.


I bought an 89 CRX HF and wehn I finally got it started I found out I had no 1st and 2nd gear. I paid a junkyard to swap in a trans. It was supposed to be out of another HF...I know it wasnt because I drove the HF to the junkyard. It was going 80 mph in 5th gear at about 2000rpm ...... On the way home it drove much quicker (0-60) feels just like my sons 90 CRX DX. The tach said I think over 3500 at 80 mph.
 

Periculum

Senior Member
The tranny isnt for me, its for a friend with a 1st gen. I figured the tourque was similar enough, but since he was doing mostly fifth gear driving, that the change in MPG for 1-4 would be minor and the change in 5th would make a difference.
 

Airjockie

Watanabe Whore!!!
Rest In Peace
for the 84-87 trany's...to get the 5th gear.....you don't have to swap the trannies. You don't even need to remove the tranny. Just pop the tip cap nearest to the passengers wheel, and the 5th gear is located right there...pop the gear out of the SI tranny, put the HF gear in, button it up, call it done....some oil might be spilt out, but not enough to even worry about adding more oil.
 
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