cx head to dx head?
09-18-2005, 07:09 AM
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cx head to dx head?
I have a 92 cx and was wondering what you would have to do to put a dx 16 valve head on. Would you just bolt it on and replace gaskets or what? Would my ecu work with that head?
09-18-2005, 07:34 AM
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Re: cx head to dx head? (T-78RX7)
No, its not that simple. Your pistons only have reliefs for 8 valves. 16v heads will collide, and you will not be happy.
buy a longblock and call it a day.
buy a longblock and call it a day.
09-18-2005, 07:37 AM
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Re: cx head to dx head? (Mleach)
I was told that cx civics had either domed pistons or 4 releif pistons. I didn't think there was a 2 relief piston.
09-18-2005, 09:22 AM
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Re: cx head to dx head? (T-78RX7)
just get a dx longblock or better yet ex longblock and then you're good to go......dont even mess the cx bottomend .....slowest motor in world
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09-18-2005, 11:30 AM
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Re: cx head to dx head? (HONDA92HATCH)
my old cx had 4 valve reliefs. if you are going to go through all that trouble, I would just swap the whole engine and get rid of that pos trans while you're at it 
09-18-2005, 12:42 PM
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Re: cx head to dx head? (T-78RX7)
You can just bolt it on and your ecu will work. Don't listen about the relief cuts. If this was true there wouldn't be too many mini-me conversions out there. If your going through the trouble of swapping the heads why not save up some money and put a Z6 head on it. You will have to do some more work and spend more money, but it's worth it over your stock cx motor. Here is a link for the mini me swap.
https://honda-tech.com/zerothread?id=554053
https://honda-tech.com/zerothread?id=554053
09-18-2005, 12:45 PM
#13
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Only the very early (first month or two of production) 92 CX motors had the 2 valve relief pistons, all the rest had P06 pistons (same as a DX). The DX head bolts right on with no issues whatsoever, but you may very seriously want to upgrade to at least the DX intake manifold/throttle body. In the future, an EX/Si tranny is another great upgrade for the CX motor.
I built a minime out of a CX motor once with a Z6 head, Y8 manifold, DC header, Ex tranny, Fidanza flywheel, Exedy clutch, and one of those red ebay valve covers. It was one of the best motors I've ever had.
I built a minime out of a CX motor once with a Z6 head, Y8 manifold, DC header, Ex tranny, Fidanza flywheel, Exedy clutch, and one of those red ebay valve covers. It was one of the best motors I've ever had.
09-18-2005, 01:28 PM
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Re: (Kendall)
I have a '92 CX, and when I was replacing the headgasket (with a Y8 gasket) I noticed that the pistons had 4 valve reliefs. It would be extremely rare to find a CX engine with 2 valve reliefs, because even some CRX HF motors came with the P06 pistons.
Slapping on a DX head would be a worthy mod to the CX engine. This way you don't have to pay for an expensive Z6 ECU, no fiddling with wiring (which really isn't that hard) and it would be very inexpensive. Yes, definitely get at least a DX intake manifold. Swapping out the trannys would be another huge improvement over the CX tranny. But if you DID choose to go the Z6 route, you'll have even more power.
Since I'm gonna keep my CX engine for such a long time (saving up for ITR swap), I plan on at least swapping out the tranny. But if I run into a DX head for cheap, I'll most likely go with that as well. While the head's off, I plan on shaving about 20 thousanths off the head, and continue using my Y8 headgasket, along with a simple portmatching job on the intake side and hopefully a Z6 intake manifold. I would also use a DX ECU.
Or maybe I'll just throw in the new tranny and forget about the rest.
Either way, just know that the D15B8 block is pretty much exactly the same as the DX block - the major difference between the CX and the DX engine is the head/IM and transmission. I'd also recommend swapping out the ECU as well, given that a DX engine came with a 4-wire O2 sensor, and our CX's only use a silly 1-wire... That and the fact that the DX had 30 more HP, it's safe to say that the fuel/timing maps are VERY different.
Good luck on your decision!
Slapping on a DX head would be a worthy mod to the CX engine. This way you don't have to pay for an expensive Z6 ECU, no fiddling with wiring (which really isn't that hard) and it would be very inexpensive. Yes, definitely get at least a DX intake manifold. Swapping out the trannys would be another huge improvement over the CX tranny. But if you DID choose to go the Z6 route, you'll have even more power.
Since I'm gonna keep my CX engine for such a long time (saving up for ITR swap), I plan on at least swapping out the tranny. But if I run into a DX head for cheap, I'll most likely go with that as well. While the head's off, I plan on shaving about 20 thousanths off the head, and continue using my Y8 headgasket, along with a simple portmatching job on the intake side and hopefully a Z6 intake manifold. I would also use a DX ECU.
Or maybe I'll just throw in the new tranny and forget about the rest.
Either way, just know that the D15B8 block is pretty much exactly the same as the DX block - the major difference between the CX and the DX engine is the head/IM and transmission. I'd also recommend swapping out the ECU as well, given that a DX engine came with a 4-wire O2 sensor, and our CX's only use a silly 1-wire... That and the fact that the DX had 30 more HP, it's safe to say that the fuel/timing maps are VERY different.
Good luck on your decision!
09-18-2005, 05:12 PM
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Re: (MrTodd)
So to swap heads to a dx head I would just need the head, gaskets, and would I have to get new head bolts? What about the ecu could I use the cx ecu?
09-18-2005, 07:51 PM
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Re: (T-78RX7)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by T-78RX7 »</TD></TR><TR><TD CLASS="quote">So to swap heads to a dx head I would just need the head, gaskets, and would I have to get new head bolts? What about the ecu could I use the cx ecu?</TD></TR></TABLE>
you can use the same ecu if you want.
you can use the same ecu if you want.
09-19-2005, 02:16 PM
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Re: (T-78RX7)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by T-78RX7 »</TD></TR><TR><TD CLASS="quote">The ecu's are closer than a z6 ecu.</TD></TR></TABLE>
what??????
what??????
09-19-2005, 10:15 PM
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Re: (T-78RX7)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by T-78RX7 »</TD></TR><TR><TD CLASS="quote">The cx ecu would work better with a dx head, than with a vtec head.</TD></TR></TABLE>
Yes, but even so it's a horrible match with even the DX head. Keep in mind that the CX ECU has a revlimiter that kicks in just before 6000 rpm.. The DX head still has plenty of room to breath past 6k, so you'd be falling short of the full powerband. And AGAIN, the DX engine puts out 30 more HP than the CX; the DX ECU has VERY different fuel and timing maps to help the DX motor express that power. The CX ECU is a MAJOR restriction.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kaiba »</TD></TR><TR><TD CLASS="quote">If you're gonna swap the head, i hope you get the dx intake manifold too.</TD></TR></TABLE>
I agree. Remember that the CX manifold was designed for an 8-valve head. The throttlebody and plenum are TINY, along with the runners - not nearly big enough for a 16-valve DX head. Another bottle-neck that should be changed.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by T-78RX7 »</TD></TR><TR><TD CLASS="quote">So to swap heads to a dx head I would just need the head, gaskets, and would I have to get new head bolts? What about the ecu could I use the cx ecu?</TD></TR></TABLE>
To swap heads you'll need a new headgasket. I would buy either a Z6 or Y8 headgasket, since they are a 3-layered metal gasket they are stronger than the original graphite composite gasket, and also thinner yielding a higher compression ratio. So in and of itself, replacing the headgasket will be a performance benefit.. Also, if you did reuse the stock composite gasket, it would end up leaking.
You can re-use the stock headbolts, they will fit/function with no problems. If someone says you must replace them, they've never had any real experience swapping out a head. Yes they do stretch, but for a stock application it makes no difference.
As mentioned above, use at least a DX intake manifold. You can also use a Z6 or a Y8 intake manifold for even better performance. You will need a new intake manifold gasket, because the CX gasket port openings will be too small and off center.
Use a DX ecu - you will have to add 3 more wires for a 4-wire O2 sensor... You could keep the stock 1-wire sensor in, but you'll have a constant CEL and your gas mileage will suffer.
When replacing the head it's a very good idea to do some maintenance work. That is, since everything is taken apart and you have room in the engine bay.. Replace the water pump, timing belt, valve cover gaskets, maybe even the cam seals. Adjusting the valve lash on the new head wouldn't hurt either. These items are not required, but you might as well do them since you'll be fiddling with them anyway - at least the water pump and t-belt!
If the wiring and head removal procedure is above your head, you'd better start doing your homework. Research! Those mini-me write-ups (as mentioned above) are an excellent place to start. A HELMS manual will help a LOT.
Good luck.
Yes, but even so it's a horrible match with even the DX head. Keep in mind that the CX ECU has a revlimiter that kicks in just before 6000 rpm.. The DX head still has plenty of room to breath past 6k, so you'd be falling short of the full powerband. And AGAIN, the DX engine puts out 30 more HP than the CX; the DX ECU has VERY different fuel and timing maps to help the DX motor express that power. The CX ECU is a MAJOR restriction.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kaiba »</TD></TR><TR><TD CLASS="quote">If you're gonna swap the head, i hope you get the dx intake manifold too.</TD></TR></TABLE>
I agree. Remember that the CX manifold was designed for an 8-valve head. The throttlebody and plenum are TINY, along with the runners - not nearly big enough for a 16-valve DX head. Another bottle-neck that should be changed.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by T-78RX7 »</TD></TR><TR><TD CLASS="quote">So to swap heads to a dx head I would just need the head, gaskets, and would I have to get new head bolts? What about the ecu could I use the cx ecu?</TD></TR></TABLE>
To swap heads you'll need a new headgasket. I would buy either a Z6 or Y8 headgasket, since they are a 3-layered metal gasket they are stronger than the original graphite composite gasket, and also thinner yielding a higher compression ratio. So in and of itself, replacing the headgasket will be a performance benefit.. Also, if you did reuse the stock composite gasket, it would end up leaking.
You can re-use the stock headbolts, they will fit/function with no problems. If someone says you must replace them, they've never had any real experience swapping out a head. Yes they do stretch, but for a stock application it makes no difference.
As mentioned above, use at least a DX intake manifold. You can also use a Z6 or a Y8 intake manifold for even better performance. You will need a new intake manifold gasket, because the CX gasket port openings will be too small and off center.
Use a DX ecu - you will have to add 3 more wires for a 4-wire O2 sensor... You could keep the stock 1-wire sensor in, but you'll have a constant CEL and your gas mileage will suffer.
When replacing the head it's a very good idea to do some maintenance work. That is, since everything is taken apart and you have room in the engine bay.. Replace the water pump, timing belt, valve cover gaskets, maybe even the cam seals. Adjusting the valve lash on the new head wouldn't hurt either. These items are not required, but you might as well do them since you'll be fiddling with them anyway - at least the water pump and t-belt!
If the wiring and head removal procedure is above your head, you'd better start doing your homework. Research! Those mini-me write-ups (as mentioned above) are an excellent place to start. A HELMS manual will help a LOT.
Good luck.
