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Discussion Starter #1
OK guys, got a 1991 CRX HF with one hell of a frankenmotor...

D15b1 head - EF 4 speed DPFI
D15b2 block - EF DX 5 speed DPFI
ALL 16 valve instead of the original 8 valve
HF transmission

Currently installed and considering swapping:
D15b6 intake/TB/ecu
DC sport headers, no cat, full catback thermal r&d exhaust.

for:

D16a6 ecu, intake, fuel rail and injectors, TB
.
With the current setup, I have stumbling all over 2k rpm under light load, and about 30MPG, No CEL and otherwise reliable.

I tried the D16A6 ecu on the D15B6 fuel/air setup, got rid of stumbling but added pinging under load all across the board. Haven't verified timing yet, but will do that soon.

My goal here is driveability and MPG under $200. Paid 40 for the ecu, and have a lead on the rest of the list for $80. I'm not opposed to swapping the cam, but I am not, at this point, considering any motor swaps. I'd rather try to get this longblock to run better. It doesn't burn oil and seems to be in excellent condition.

Thoughts?
 

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Brokedick Millionaire
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40,267 Posts
D15B1/2 block/head, they are the same. D16A6 intake, ECU, injectors, convert to MPFI wiring harness if still using DPFI, or keep HF harness

Never EVER use 4th or 5th gear in the HF trans.

Shift at 3600-4000 rpms, get 45 mpg.

HF 1-2-3 is nearly the same as JDM close ratio ZC trans shifting 1-3-5, which I have in my 390,000 CRX HF with D16A6 motor.

Get rid of the header, stock cast iron D16A6 or D15B7 exhaust manifold is better for mpg.

D15Beast7, 145 chp got a best of 53 mpg on pure gas
D16A6/Y8 on stock A6 ECU in my CRX HF and close ratio ZC trans, 48 mpg at 60 mph. 72 mph it drops to 40 mpg. I have to push beyond that to get below 40 mpg.
 

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Bolt on an a6 intake, injectors and TB and use the a6 ECU and you should be fine for driveability.
 
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