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My DD 1991 CRX DOHC ZC Turbo HX35

29469 Views 118 Replies 20 Participants Last post by  seandonn
Decided to finally do a build thread. This was my first car when I was 15 and I've been building for 6 years now. Might as well start from the beginning:

Bought a 91 CRX Hf for $500 at an auction. It was 100% stock and fairly clean minus some faded interior and crappy body work. Pretty much sold the engine and anything else I didn't need. I love the HF engines, but I wanted more than 60hp :D

Since the interior looked like crap I redid it...can you tell I liked Pimp My Ride?

First was a Integra ZC (basically a D16A1) with ZC internals. Needed to make a special driver's side bracket. I got what I thought was Si transmission, but it was a 4-speed, lesson learned.
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After a while I started doing body work to paint it. It basically looked like a cow with primered spots for months.

Got it painted Orange Metallic, not bad for my first time.

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Swapped out the interior when it started to fade and look bad. Got a full Si interior and swapped it in.

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Then basically I wanted more power so I got a sleeved DOHC ZC block and build it up. The bores were tapered and out of round but I decided to just go with it. It smoked pretty bad, and also had valve guide issues. I swapped another DOHC ZC I had lying around into it. Then I decided I needed some 75.5mm+ pistons so I could bore it out to fix the issue, but I would have to get some custom made ones.

Repainted it last summer, but the color was different than what it was suppose to be (little darker orange). I might repaint it this summer with some Honda OEM Orange paint, so I get the exact color I want.

Got another DOHC ZC block I had and put the pistons from the last engine into it along with some other parts. Then got the whole turbo setup on after a little NA break-in. I basically made most of the turbo parts, so it took quite a bit of time.

Here is how it sits now, drives great but will be seeing more boost in the near future.

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List of what all is done to it at the moment:


75.5mm Race Engineering/Wiseco Forged Pistons
Eagle Rods
GSR Throttle Body
OBD1 P29 Intake Manifold
AEM Fuel Rail/AN engine bay lines
B&M Regulator
Hiprofile 800cc Injectors
Cometic Head Gasket
King Bearings
B16A ARP Head studs
All New Honda OEM Gaskets/Seals/Sensors
OEM Valvetrain and cams
Powdercoated Wrinkle Black Valve Cover/Intake/Cam Gears done by yours truly.
Hasport 88A mounts
Wire Tuck/Battery relocated
Custom 2.5" exhaust with Dynomax muffler in rear, generic muffler in the middle and Catalytic Converter (yes real cat, I passed emissions in this car in March)
CXracing 1/2 Radiator


Si Cable Transmission with phantom grip LSD, will be rebuilding and installing Mfactory LSD this Summer.
ACT Xtreme Clutch with ACT Flywheel (12lbs IIRC)


Omni Power Coilovers (10Kg/mm in front and 12Kg/mm in rear)
PIC Rear Lower Control Arms
DA Rear Disc Brakes
Energy Suspension Bushings all around.
K-tuned Traction Bar


Si Interior
Civic Si passenger seat and Scat Race Driver's seat
Prosport Gauges with one button heater
Roll Bar (Guess you would call it a 4-point now)
OBD1 converted on Neptune RTP (tuned by me)


Wings West Urethane Body Kit (thick rubber, stronger than stock or else I wouldn't of got it)
Summit Racing Orange Metallic paint
XXR 002 15" +38 offset

Turbo Setup:

HX35 Turbo
Custom Manifold with true twin scroll setup
Custom 2.5" intercooler piping
Custom Oil lines
Custom Downpipe
Go-autoworks Medium Intercooler
Turbonetics Raptor BOV
Tial 38mm Wastegate with 10psi spring

That's all I can think of off the top of my head. I basically did everything myself, I don't like other people working on my car so I had to learn how to do everything. Right now I street tuned it and drives great, starts getting into boost around 2500-3000rpm and full boost comes around 4500rpm, you gotta love divided housings :)
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Nice build i like the color you choose for the bay what is the name of the color
Nice build i like the color you choose for the bay what is the name of the color
It's Ultra Blue Pearl, just a basic Blue Pearl. Got the paint from summit racing.
i like the paint on the motor, looks great! is it dynoed?
It's all powdercoating, will last forever. Not dyno'd but if I had to guess I would say at least 200whp, it's a pretty conservative tune so there is more power to be had at this boost level.
Does anyone know what max ignition timing should be about? When I say max timing I mean 5K-7Krpm at full boost (9.9psi in my case). Is 20 degrees fine or still too much?
i like how this transformed, did a good job making it look how it does now!

I highly dislike screws blasted into thin sheet metal. It will pull eventually and cause headaches. This is the proper thing to use:

That is Aviation level crap. You don't need anything quite so fancy, but, you get the general idea. The second tool in the video can easily be made with good hardware.

Support that line in the middle or else. You've been warned.
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That's a bad picture of the oil line, you don't see by the engine mount there is nylon clamp and by the headlight housing. It moves side to side maybe an half inch, doesn't come close to anything.

That's good advice for the intercooler mount, never though of using rivets. I actually tack welded the bracket to the body because it looked kind of weak. I guess I didn't take a picture before I put the bumper back on, next time I have the bumper off I will take some more pics.
A nylon clamp on a SS braided line . . . Yeah . . .

I've seen SS braid eat through a cast iron block. Also, those lines are not meant to support their own weight over spans. This WILL weaken it over time.

<---- doesn't mess with braided lines for many reasons.
A nylon clamp on a SS braided line . . . Yeah . . .

I've seen SS braid eat through a cast iron block. Also, those lines are not meant to support their own weight over spans. This WILL weaken it over time.

<---- doesn't mess with braided lines for many reasons.
What do you use for turbo feed lines then? All the ones I've seen made and sold are steel-braided. I wouldn't trust some rubber line or hard line, don't know what else there is.

The line is supported in about 3 spots, I don't really see it weakening soon but I do agree over a long time it will rub. I check over everything almost daily.
CRX is running good, could use a little tuning at part throttle though. Here are some things I fixed:

-Vacuum line from compressor housing to wastegate, then added another fitting on the charge piping by the bov so the hose is only 1/2 foot. Instead of all the way from the compressor housing to the bov.

-Did a boost leak test and the BOV flange was leaking slightly (had a cheap aluminum screw on one, just cut a steel flange out and welded it on). Seems all good now.

-The fitting on the compressor housing was the one that came with it. I found it had a pin hole in it, then when I took it out it was some weird restrictor fitting which is probably why I had some boost creep at the top of 3rd gear and 4th. Replaced it with a normal fitting. Picture below of original fitting (opening was the size of a needle)

The To-Do-List for the summer:

-Make my 3" exhaust with 3" downpipe (if I can get the 3" downpipe to fit).
-Replace Lower control bushings, ball joints, and front brakes
-Make better radiator fan shroud (thin metal on mine)
-Replace lower injector seals
-Build a no-slop shifter (fine now, but can always be better)
-Build or just buy front stabilizer bars (from front LCA to chassis, rear traction bar)
-Get some 22x8x13 slicks and wheels
-Up the boost to 15-18psi and do some track tuning and hopefully hit some mid 11's.

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Nicely done!
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