109 replies to this topic

[firstgencrx]

Hello All!

I was not 100 percent sure where I should put this thread. I stuck it here because, well, it's a build thread!

What I'm going to try and do, with some help from the list, is come up with an adapter system for people wanting to run a later model OBD0/OBD1 distributor on their earlier pre-OBD engine. More specifically, the D15A2/D15A3 and the D16A1. I know there could be a half dozen possible combinations for this, so I am limiting it to what I hope will be the most common engines that could benefit the most from being able to have more spark control.

This is where I could use some input from the list. I know what I would do for myself, but that doesn't mean it's a popular decision. I am still learning about Honda/Acura engine and cylinder head codes, as well as the codes of popular distributors. So if I get any of these part numbers wrong, please chime in and correct me.

The engines I have chosen for this project are the:

1. The D15A2 (PE3 cylinder head) carburated 12 valve (Canadian non-CVCC) from the 84-87 CRX/CIVIC (maybe the PEO CVCC as well?).
2. The D15A3 (PE7 cylinder head) fuel injected 12 valve Si from the 85-87 CRX/CIVIC.
3. The D16A1 (HM3 and HM4 cylinder heads) fuel injected 16 valve dual overhead from the 86-87 (HM3) and 88-89 (HM4) Acura Integra.

Did I get those engine and cylinder head numbers right?

Now I know some people run carbs. What I don't know is if they run mechanical fuel pumps off the end of the camshaft like they do on the PEO cylinder heads commonly found on the D15A2. If that is the case, what I want to know is if the cylinder head setup used on the American version of the CVCC D15A2 (PEO cylinder head) has the same distributor mounting as the Canadian non-CVCC D15A2 (PE3 cylinder head). If so, I can just use the PEO I have here in the shop to fit-up the new distributors.

***OR*** do the carburetor people just run electric pumps, using the PE3 head with the short Si cams and eliminate the block that the mechanical fuel pump normally mounts up to?

I am still not 100 percent sure on which distributors to use and would love to get some input on this as well. Here is what I am thinking and why:

For the OBD0 distributor: I chose the TD18U from the 88-91 1.6L CRX. It's a multi-port fuel injected, non-VTEC engine and the distributors are easy to find.

For the OBD1 distributor: I chose the TD41U from the 92-95 1.5L/1.6L CIVIC because it's a multi-port fuel injected, non-VTEC engine and the distributors are also easy to find.

Once I get 100 percent clear on which OBD0 and OBD1 distributors to run, I will start fitting up and cutting aluminum! As usual, I will take lots of pictures so you can follow along and watch me make mistakes! Well, maybe little mistakes.

I am also compiling a list of Honda/Acura cylinder head codes for the Wiki as well. Some of you may have already seen my post for the common ECU's and distributors I posted earlier. I put it there after collecting the information from the research I have completed already on this project.

Anywho, any thoughts from the group would be appreciated. Blast away people!

David

[DEIVIONCRX]

Im not a 100%(can be tomorrow) but i think the 1.5(HF/DX) and 1.6(Si) 88-91 distrubitors have the same mounting, just a slight difference in the wiring, the 1.5 has round plugs, and the 1.6 has square.

The OBD1's arnt the same however (1.5 was Non-Vtec, 1.6 was VTEC) but i think 2 bolts line up, so you could simply put 2 threaded holes on there, one for 1.6 and one for 1.5, all the OBD1 wiring is the same.

[D Jaws II]

That can be done??? No chit???

Well, now that you put it that way, hmmmmmmmmmmm.

Which dizzy would be better for a D15A3 SI with a .060 shaved head (PE7), Prelude injectors, adjustable fuel pressure, cam gear, decked .006 block with PM7 pistons (hehe) and header? I currently run a PG7 ECU? And it runs real lean.

Now if one uses either of those two dizzy's, which ECU to get (assuming like the one that came with the dizzy) and what wiring needs to be done to do the change over? Harness (interior and engine???) and cluster from a donor car, yes?

I suppose that if one needs to change the ECU then I can put a socket into it and re-program the fuel/spark? Yes/No? This could get real interesting, quickly!

Do you have MORE control of the spark with OBD1 or OBD0? Or are they essentially the same?

Any ideas?


Great job David, you are a magician.

Drooling with anticipation.


Regards,


Donnie

[3GCVC]

good work i will definately take one for the EW.

afaik for the D16A or ZC a JDM B20A Dizzy should fit on and be OBD 0/1 compliant but i will look into this more.
i believe the blacktop D16s with the 1st gen mounts do already have an OBD0 compatiable dizzy, they definately do have a different bolt on patten to a browntop so you may not need to design anything for that.

[Maine_Honda_Racer]

if the EW1 and the d16a6 have the same mounting pattern, why is there a gent selling a 350 dollar conversion plate, I'm not inclined to believe it until I see it myself.......

[firstgencrx]

if the EW1 and the d16a6 have the same mounting pattern, why is there a gent selling a 350 dollar conversion plate, I'm not inclined to believe it until I see it myself.......

I saw someone mention the high price before. My first thought was "No Effin Way!" It can't be that big a deal. The things that attracted me to this project was that it looked interesting, and I knew I could do it for a price people would be happy with. I am going to guess the adaption kit will be some kind of aluminum adapter plate, and a modified drive button on the end of the dizy. I will know more when I rip into it.

I will "show it all" and everyone will get a chance to really see what's involved.

Thanks and take care,

David

[Maine_Honda_Racer]

I've been thinking on this myself. You probably saw me mention it. The justifaction for the price from the manufacturer of that part is that he is the only one that makes one. All it needs to be is two things: One a machined piece of metal which has holes to bolt to the block and milling to countersink bolts into that adapter, it then needs to have threaded holes for the new distributor to bolt to. The distributor input shaft would have to be lengthened by the width of the adapter plate. If I had access to the right tools I don't see why this should take more than a couple of hours of measuring and cutting to get it right! I'd buy one in a heartbeat if the price was somewhere in the non-insane zone.

If I can help you in any way, let me know!

[firstgencrx]

Donnie! You are just a big trouble maker!

Now your making me wake up and think...

That can be done??? No chit???

Well, now that you put it that way, hmmmmmmmmmmm.

Which dizzy would be better for a D15A3 SI with a .060 shaved head (PE7), Prelude injectors, adjustable fuel pressure, cam gear, decked .006 block with PM7 pistons (hehe) and header? I currently run a PG7 ECU? And it runs real lean.

From what I know of the PG7, you would need to be running the 88-89 version that had ignition advance control. The 86-87 model relied on vacuum advance for the distributor. This is another reason why I think the distributors for the 86-87 and 88-89 Integra D16A1 engines are different. The mounting for the dizy between the HM3 and HM4 cylinder heads might also be different. I guess a trip to the local auto wrecker is in order.

Now if one uses either of those two dizzy's, which ECU to get (assuming like the one that came with the dizzy) and what wiring needs to be done to do the change over? Harness (interior and engine???) and cluster from a donor car, yes?

That's a great question. If the person who is using the adaption kit is NOT using one of the after market ignition control systems, I would assume the ECU that came from the distributor. But, and this is a big but because I am still learning here... I bet you could use any ECU that's from a multi-port, non-VTEC engine as long as the dizy OBD version matched the ECU OBD version. I know from the pgmfi.org site, some ECU's are more tweakable than others. I will do some more research on this and see which ECU's seem to be the preferred models for tuning.

As far as wiring, you would definitely need to change out the harness enough to accept the later model ECU.

I suppose that if one needs to change the ECU then I can put a socket into it and re-program the fuel/spark? Yes/No? This could get real interesting, quickly!

I have read many articles about modifying some Honda ECU's to accept USB/Serial ports so you "can" get into the system with a laptop and make changes to fuel mapping and spark control. Now this stuff is not for the faint of heart, but I am assuming (I know! I know! Never assume, it makes an ASS out of U and ME) anyone interested in this adapter kit would be a serious tweaker. Or, just willing to roll up their sleeves and do some serious learning.

Do you have MORE control of the spark with OBD1 or OBD0? Or are they essentially the same?

Another super question! I have know idea. Anybody? I am not sure if we even need to offer a choice. It's possible we could achieve our goals with either the OBD0 or OBD1 dizy's.

I did hear/read somewhere (so don't rely on this) that the more high end engine management control systems from companies like Hondata have more tuning abilities from an OBD1 system than the OBD0. Now, if this means better spark control? I have know idea. I would assume (there, I did it again) the best systems for spark control would come from companies that specialize in just that, like the MSD line of "Digital 7" programmable controllers.

Well, I hope I answered your questions as best I could. I will keep up the pace learning about this stuff (it's more fun than you would think!) and post again when I have some new info. In the mean time, please keep the thoughts coming people! It's possible none of this is worth it and we are waisting our time, but we won't know if we don't try!

Take care all!

David

[Maine_Honda_Racer]

You could not use the distributor from a d16a1 in this conversion project. The d16a1 has an independent crank angle sensor that is not built into the distributor and the computer would be very confused. I too am uncertain if obd0 and obd1 have any difference in their tuneability. You could certainly run your car on any computer that matched the distributor you used. If the plate was designed for a d16a6 OBD0 distributor like I was hoping for, the plugs have the same number of wires, just a different shape. This would allow for utilization by anyone with a street car, or for the racer a plug and play with a d16a6 wiring harness. That computer is nicely programable, either with a serial cable after modification to the box, a solid soldered chip for those who have internal ECU visual inspections, or with a socket that could recieve variously programmed chips for those whose ECU's only recieved an external inspection. Of course that ECU would also be compatible with your various standalone engine management systems like Megasquirt, Haltech, Chrome, etc....

Just my 02 meter's worth.

[firstgencrx]

You could not use the distributor from a d16a1 in this conversion project. The d16a1 has an independent crank angle sensor that is not built into the distributor and the computer would be very confused. I too am uncertain if obd0 and obd1 have any difference in their tuneability. You could certainly run your car on any computer that matched the distributor you used. If the plate was designed for a d16a6 OBD0 distributor like I was hoping for, the plugs have the same number of wires, just a different shape. This would allow for utilization by anyone with a street car, or for the racer a plug and play with a d16a6 wiring harness. That computer is nicely programable, either with a serial cable after modification to the box, a solid soldered chip for those who have internal ECU visual inspections, or with a socket that could recieve variously programmed chips for those whose ECU's only recieved an external inspection. Of course that ECU would also be compatible with your various standalone engine management systems like Megasquirt, Haltech, Chrome, etc....

Just my 02 meter's worth.

Sounds like it's worth more than two cents to me! Thanks for the input. So is that the TD18U distributor?

David

[Maine_Honda_Racer]

Yes David, that is exactly the number. As I mentioned in PM, I have several in my race garage which I'd be happy to donate to the cause.

[strudel]

David,
I have pictures of the conversion in my files as I researched this a long time ago. As I recall, wasn't the problem to do with people running a vacuum advance (browntop) head in a normal browntop or that head on a different block( eg blacktop or Hydra conversion) for whatever reason. So in doing this they wanted to use electronic advance as well as in the D15 1/3G cars for better tunability. Naturally one would have to change ECU's to accommodate the new system. So in essence use a D16A1 electronic dizzy for all of the above applications. I know nothing about the other style dizzy's from newer engines as I am at the moment still only OBD0 smart. Add a number and I get totally lost. Did this all sound as a reasonable explanation? JS

[Maine_Honda_Racer]

David,
I have pictures of the conversion in my files as I researched this a long time ago. As I recall, wasn't the problem to do with people running a vacuum advance (browntop) head in a normal browntop or that head on a different block( eg blacktop or Hydra conversion) for whatever reason. So in doing this they wanted to use electronic advance as well as in the D15 1/3G cars for better tunability. Naturally one would have to change ECU's to accommodate the new system. So in essence use a D16A1 electronic dizzy for all of the above applications. I know nothing about the other style dizzy's from newer engines as I am at the moment still only OBD0 smart. Add a number and I get totally lost. Did this all sound as a reasonable explanation? JS

All sound, except for the d16a1. It does not have an internal crank angle sensor.......

[strudel]

All sound, except for the d16a1. It does not have an internal crank angle sensor.......

Oh, I realize that. So to clarify, my point with a DOHC head I should be accurate but not with using a D16A1 blacktop dizzy for a D15A3 in 1G CRX or 3G Civic, I wasn't thinking about that part. What dizzy is the preferred unit of choice to change that to a electronic advance and what ECU? JS

[firstgencrx]

Oh, I realize that. So to clarify, my point with a DOHC head I should be accurate but not with using a D16A1 blacktop dizzy for a D15A3 in 1G CRX or 3G Civic, I wasn't thinking about that part. What dizzy is the preferred unit of choice to change that to a electronic advance and what ECU? JS

Jerry,

If it where me, I would just use the ones I listed above. I have been talking with both Maine_Honda_Racer and 87MugenProCR-X. They feel strong about the TD18U from the D16A6 for the OBD0 choice. Apparently the PM6 ECU you would use with the distributor is super hackable.

Take care,

David