50 replies to this topic

[zakats]

your stock intake and carb will do- after you plug the cvcc ports (more to go into there, when you're ready I'll fill you in). The stock Si suffers from a super low compression ratio so, if you wanted, you could have he head milled down ~.030 and do some minor home porting.

there is something to the EF brakes that work almost the same as the common teg brake swap- I don't remember the particulars but I recall their being just as good as teg brakes, not a bad way to go.

I love the austin roads, I'm sure there is a lot of fun to be had there in a formidable car.

[TexanIdiot25]

I want nothing to do with the stock Honda carb ever again. Making EFI work is worth the trouble if I'm swapping the motor. If I'm not mistaken, all that's needed is the right wiring harness, and fuel return line/sending unit to the tank?

[zakats]

I attempted a wire harness swap once, it was a massive pain in the ass in that you have to remove almost everything under the dash in order to swap the chassis harness- no it is NOT worth it. It isn't as simple as swapping the engine harness and a few other things, it is a lengthy and involved process. I ended up making my own, hybridized harness. I'd go megasquirt before converting to the crappy OEM pgmfi. If you were swapping to the vx/hx engine as you've mentioned before, the OE EFI swap would actually be worth doing.

The stock carb isn't so bad, just takes some time to understand it- from there it is just as simple as any other. The mess vacuum tubes is not necessary for proper operation so don't let that scare you. There is also the CDM non cvcc carb and the weber.

[Gant]

From my experience, the stock carb-devacd had a much broader power band than the weber I had. I liked it a lot more, even if it was only for a few days and I got 40 mpg @ 70 mph with devacd stock carb vs. 35 MAX @ 60 with the weber

PLUS the whole harness swap thing is a HUGE PITA!!! if you decide to go fi.
ask me how I know

[TexanIdiot25]

I attempted a wire harness swap once, it was a massive pain in the ass in that you have to remove almost everything under the dash in order to swap the chassis harness- no it is NOT worth it. It isn't as simple as swapping the engine harness and a few other things, it is a lengthy and involved process. I ended up making my own, hybridized harness. I'd go megasquirt before converting to the crappy OEM pgmfi. If you were swapping to the vx/hx engine as you've mentioned before, the OE EFI swap would actually be worth doing.

The stock carb isn't so bad, just takes some time to understand it- from there it is just as simple as any other. The mess vacuum tubes is not necessary for proper operation so don't let that scare you. There is also the CDM non cvcc carb and the weber.

Do you have a build thread? I was looking for one last night of your previous projects to see if I could find your carb swap or what-not.

From my experience, the stock carb-devacd had a much broader power band than the weber I had. I liked it a lot more, even if it was only for a few days and I got 40 mpg @ 70 mph with devacd stock carb vs. 35 MAX @ 60 with the weber

PLUS the whole harness swap thing is a HUGE PITA!!! if you decide to go fi.
ask me how I know

How do ya' know?

[badpenny]

You need to excuse Gantface, he's an Ooozing Vagina, He also says stuff like, "Its too Hot," and "It itches down there today", the wiring swap is what you make of it. Depending on how fast you work, and if you have a shaded area to work in, you can accomplish it in a day, without much dehydration. When you do your wiring swap, slit the tape on all casing (under the carpet) this will make replacement simple. Plus you already have the hole cut for your ecu on the passengers side, so the si ecu mounts right up. You will need to repin your harness on the drivers side with the plug from your old harness, you will need to pay careful attention to alignment and colors (a straight pic will aid in this)

[TexanIdiot25]

From what cars can I grab the harness? I don't mind wiring much, figure if I'm already doing the job might as well get EFI outta it. If time was short, I'd do the carb swap for a quicky weekend job. Nothing in plans yet though. From what donor cars can I grab a harness?

However, now that I'm settled back into Austin, I'm hating the 50hp more and more.

Edited by TexanIdiot25, 21 August 2010 - 07:28 PM.

[zakats]

You should probably stick with the 86-87 crx si but the 85 si will also work though a few plugs will be different.

you could save a huge amount of work by sticking with carb.

[TexanIdiot25]

I'd give it a shot maybe with a new carb (the throttle shafts on mine leak, amung other strange problems).

The Honda carb is more complex than the Q-Jet

[zakats]

the q-jet was made by a class of 3rd grade students back in the late 1800's, nothing could be as simple but the honda carb (keihin sp?) isn't bad, there are plenty of rebuildable units out there for dirt cheap. You might as well give it a shot at first to see how you like it, it is practically the same setup you have now and there is almost no extra work involved and you could break your build into two sections while having a working vehicle in between.... rather than beating your brains out chasing down wires/connections/grounds/sensor issues.

[TexanIdiot25]

The Q-Jet is one of the best performing OE carbs ever made, but not the simplest 4bbl to work with by any means. That goes to Holley. But it does make an evil smiley face


Mmmmmmmmmmmmmmmmm, those coke-can sized secondaries...

Can you post the CVCC block info? And what's the cruising RPM of the Si drivetrain at say, 70mph? I was thinking of either using the HF trans, or it's final drive gear if possible. I like it's tall gearing for the freeway. 75mph at 3,000 rpm is nice.

Edited by TexanIdiot25, 22 August 2010 - 04:21 PM.

[zakats]

by block info do you mean engine block? or carburetor? It has been a few years since I have taken a carb apart so the info isn't fresh. I can answer most anything of what you might want to know about the engines though.

Si and DX have the same gearsets but different final drive ratios- IIRC the Si has a 4.40 FD Cruising rpm @ 65 is about 3 or 3.5k I don't remember too well though I will say there are plenty of people out there with Si's that get 35-40mpg

The HF trans, I'm really not too sure as to the benefit of retaining it or the 5th gear but I will say that the Si could use a better 5th gear but I wouldn't want to modify anything else if sacrificing performance. The car will get great fuel economy anyways so enjoy a little pep.

[sxpkpower]

I have a HF that the previous owner had already swapped a DX engine into. With the DX engine and HF trans it would get 40 around town and just a hair under 50 on the highway. I swapped in an SI trans and now get 42 in town. I haven't been on a road trip yet, but I am sure the huge change in highway RPM is gonna drop the mileage down to closer to 40 on the highway. 60 is now almost 3000 RPM. I am going to try and swap the 5th gear from my HF trans into the SI trans to help highway RPM. The difference in acceleration around town with the trans swap is tremendous. It is much more enjoyable to drive, not to mention the difference in time on the autocross course.

I have the SI engine, computer, and wiring harness and am contemplating swapping that in as well, but this engine is in such good shape it is hard to justify tearing it out at the moment.

[TexanIdiot25]

I was thinking about that, swapping either 5th gear or the final drive if possible. I want that tall over drive of the HF. Being able to make long highway drives up near 80mph with ~3200rpm is lovely for the sake of the motor's life and highway fuel economy.

I'd imagine swapping out the whole drivetrain is as easy/easier than pulling just the motor on a FWD car, yes?

The Si's shorter 1-4th would be nice out here in Austin's hills, but honestly with more power I wouldn't mind the HF trans at all. It's fun on back roads just to stick it in 2nd and leave it there. Keeps me from speeding too much as well, top of 2nd is 60 mph, and I don't keep this motor near redline.

Zak- I was talking about the CVCC intake block. Also if carb'd, what do I do about the distributor? It's still vac advanced, but would I need a carb dizzy for it?

If I can find a cheap carb, and anything else needed, maybe I'll have to drop by houston and use-- I mean, have your guys' assistance with a quick carb'd Si swap. The car is a drag to drive out here with such little power.

Edited by TexanIdiot25, 23 August 2010 - 06:34 PM.

[TexanIdiot25]

These plastic fenders amuse me. Took the CRX out onto some nice roads today. In the tight/fast/hard braking areas, you could hear the plastic fenders cracking. Get home, open the hood, and sure enough, along the mounting holes it's splitting again. Structural rigidity FTL.