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One thing that I never see mentioned here, but often in other import and domestic threads is rod/stroke ratio. Is that one of the reasons you didn't go with the 3.7? I was quite surprised that the J32's rod/stroke ratio is around 1.88:1. I'm sure this high rod ratio also plays into the lack of torque somewhat. Surprisingly, I would think Honda would have gone for a higher max rpm on the stock motor with such a high rod ratio.
What kind of rpms are you planning on turning? With the lower lift, while higher rpms definitely need a good valvetrain, you should get better longevity out of them than with something that has a higher seat pressue right?
One thing that I never see mentioned here, but often in other import and domestic threads is rod/stroke ratio. Is that one of the reasons you didn't go with the 3.7? I was quite surprised that the J32's rod/stroke ratio is around 1.88:1. I'm sure this high rod ratio also plays into the lack of torque somewhat. Surprisingly, I would think Honda would have gone for a higher max rpm on the stock motor with such a high rod ratio.
What kind of rpms are you planning on turning? With the lower lift, while higher rpms definitely need a good valvetrain, you should get better longevity out of them than with something that has a higher seat pressue right?
The 3.7 has a stroke/rod ratio of 1.63:1 which makes for very large side load pressures. The 2.7 engine I'm building will have around 2:36:1 and at the engine speeds I'll be seeing, the will definitely relieve parasitic power in the form of friction as well as enhance the engines overall reliability factor. Because the engine will be built to handle around 8000 revs, lowering any reciprocating assembly reliability issues will make big differences in other aspects too.
I believe that it's not just the rod/stroke ratio that reduces the j-series (and most of Hondas engines in general) production of low end grunt (aka TQ) but many other things. Honda appears to prefer the high revving engine in many of their designs though not all. If you compare the j-series to say a Buick 3800 engine that is a tire roasting monster, you will see exactly what I mean. In engineering and design, they are completely different. The 3.8 was a large bore (96mm I believe) pushrod engine with two valve heads and in my research, the smaller displacement engines that carried these two details (two valve, large bore) generally produced massive torque but fell flat on their faces very quickly. I just did a quick Google search and it showed that the 3800 produced 100% of its torque by 2000 revs. Honda recognized the potential of high rev horsepower from F1 experience and applied the concept to their road cars. I'm honestly very surprised Honda ever went beyond the 3.5 in regards to displacement myself. Though the 3.7 is an awesome engine, it wasn't a predictable move on their behalf.
As for your last concern on the spring pressures, remember, I'll be running aftermarket springs that will already have a higher pressure (unknown ATM). Also, the lift on the cams will also be slightly higher as well which means more added wear on the lobes. Because I haven't actually got the cams back nor installed the springs, I do not know any factual numbers yet. I'm sure the actual seat pressure will be higher though which is good because I'll be running boost which means increased cylinder pressures. As with many other engines designed to run at high revs, the springs will probably need to be freshened up and replaced every so often. Because this is all experimental and has never been done before (to my knowledge), checking these things will done through out service life to ensure things are kept in optimal specs. I'll be doing initial tests on KMS springs which are now rated to 10.5k revs.
Just scored a J37 top-end, looking to implement it in my J35Z VCM 09 Accord. It's been a year since Honda gave me a new long block due to the piston ring issue so my warranty is done. A friend at a junkyard gave me the whole top-end for $300. Dealer sold it to him for $250, one of the heads had only a week of use before the customer blew the whole block. Other head has some toasty valves, cams don't have too much scoring on that head but either way, I'll get it worked on and benched before install.
Just need to know some things from you guys, especially YungOne who is a damn J-series guru! Will the CR be beneficial or will it actually be crappy from doing this swap?
J35Z2 block w/ J37A4 heads (respective gasket), J37A4 runners & injectors, J37A4 Manifold, J37A4 TB (since I heard the ZDX isn't worth it).
I have kTuner so the tune aspect is covered but I'm having problems on figuring out how to implement VTEC, as the iVTEC VCM system, has the oil pressure switch and VTEC solenoid on the heads.
The J37A4 has the VTEC solenoid inside the oil pump housing, just like the 6-6. My friend suggested, I swap out my oil pump housing, with the one from the 6-6, that incorporates the VTEC solenoid, not sure if it will fit though, gaskets look different.
I would have to re-wire my harness to have the VTEC and Oil Pressure switch go down to the block, I assume.
Would I need the ECU from the SH-AWD for the dual VTEC to work, doubt my iVTEC ECU will be able to control these heads?
I will also need to get the circuit made for the 2-stage butterfly valve to be functioning in the manifold, as my harness doesn't have that.
Member on DA, helped me out with that, luckily.
Wondering if my EGR will bolt up, asked RV6 if I'll need new JPipe and HFPCs, assume I will as well.
Oh and I'm sure turboGixxer will be so thrilled to re-tune my car -_- lol.
Sorry to threadjack, maybe I should start a new one.
Here's some head porn for reconciliation .
Just scored a J37 top-end, looking to implement it in my J35Z VCM 09 Accord. It's been a year since Honda gave me a new long block due to the piston ring issue so my warranty is done. A friend at a junkyard gave me the whole top-end for $300. Dealer sold it to him for $250, one of the heads had only a week of use before the customer blew the whole block. Other head has some toasty valves, cams don't have too much scoring on that head but either way, I'll get it worked on and benched before install.
Just need to know some things from you guys, especially YungOne who is a damn J-series guru! Will the CR be beneficial or will it actually be crappy from doing this swap?
J35Z2 block w/ J37A4 heads (respective gasket), J37A4 runners & injectors, J37A4 Manifold, J37A4 TB (since I heard the ZDX isn't worth it).
I have kTuner so the tune aspect is covered but I'm having problems on figuring out how to implement VTEC, as the iVTEC VCM system, has the oil pressure switch and VTEC solenoid on the heads.
The J37A4 has the VTEC solenoid inside the oil pump housing, just like the 6-6. My friend suggested, I swap out my oil pump housing, with the one from the 6-6, that incorporates the VTEC solenoid, not sure if it will fit though, gaskets look different.
I would have to re-wire my harness to have the VTEC and Oil Pressure switch go down to the block, I assume.
Would I need the ECU from the SH-AWD for the dual VTEC to work, doubt my iVTEC ECU will be able to control these heads?
I will also need to get the circuit made for the 2-stage butterfly valve to be functioning in the manifold, as my harness doesn't have that.
Member on DA, helped me out with that, luckily.
Wondering if my EGR will bolt up, asked RV6 if I'll need new JPipe and HFPCs, assume I will as well.
Oh and I'm sure turboGixxer will be so thrilled to re-tune my car -_- lol.
Sorry to threadjack, maybe I should start a new one.
Here's some head porn for reconciliation .
No Oil Pressure Switch or VTEC solenoid.
Front Head
Rear Head
Front Head
Rear Head
Did you ever figure out what needs to be done electrically to finish this swap?
I have a J37a1 in my MDX and just got my Ktuner. The wheels of building a motor have started to spin.
Is there still only 1 VTEC solenoid on the J37a2/4 like the a1?
Yes, only one vtec spool assy., and one oil pressure switch.
My OE is VCM, so I have an ECU that is VCM with a corresponding VCM harness. Due to the fact, both my heads, each have 3 SWITCHES! lol
It's a little more complicated for me.
Oil pressure switch, I have two, so I'll need to combine them and bring them down to the new one-pin, on the Oil filter housing.
Same thing with VTEC wiring, combine, and bring it down.
Problem is, I have a third switch, Rocker Arm Control Solenoid.
The ECU senses low throttle, and engages the rocker arm control solenoid, creating hydraulic pressure, locking the zero-lift lobe on the rocker into action. Creating no lift on the respective ECO cylinder valves.
I need to find out if with KTuner, I can still send spark and fuel to those cylinders. Technically, the cylinder is in free-float when this happens.
I know on 8th Gen Accord ECU's KTuner can't disable VCM yet, but can it at least send spark and fuel, I'll disable VCM by getting rid of the heads! lol.
Still looking into everything, but I did drop off the heads to get fixed up.
I really don't want to have to use a different ECU
Yes, only one vtec spool assy., and one oil pressure switch.
My OE is VCM, so I have an ECU that is VCM with a corresponding VCM harness. Due to the fact, both my heads, each have 3 SWITCHES! lol
It's a little more complicated for me.
Oil pressure switch, I have two, so I'll need to combine them and bring them down to the new one-pin, on the Oil filter housing.
Same thing with VTEC wiring, combine, and bring it down.
Problem is, I have a third switch, Rocker Arm Control Solenoid.
The ECU senses low throttle, and engages the rocker arm control solenoid, creating hydraulic pressure, locking the zero-lift lobe on the rocker into action. Creating no lift on the respective ECO cylinder valves.
I need to find out if with KTuner, I can still send spark and fuel to those cylinders. Technically, the cylinder is in free-float when this happens.
I know on 8th Gen Accord ECU's KTuner can't disable VCM yet, but can it at least send spark and fuel, I'll disable VCM by getting rid of the heads! lol.
Still looking into everything, but I did drop off the heads to get fixed up.
I really don't want to have to use a different ECU
Hey, i joined up here just specifically to give you this tip and see if it might help. Im in the process of buidling my J35z in mu '11 pilot and ran across this thread. What alot of us over on piloteers.org did to disable the VCM was to put a 100 ohm resistor inline of one of the wires of engine coolant sensor #2 (the one by the thermostat, not the one in the radiator). this makes the ecu think the engine is running a little colder than it is and vcm only works when the engine is at normal operating temperature. you will notice a slight decrease on your temp gauge, but the warning system is still hooked into ect#1 so you wont have to worry about not knowing if you over heat, eitherway, you would still see your needle climbing. hope this helps. that damn VCM was a thorn in my side from day one. ill be following this thread, its sad that i cant go on a forum for my own truck for info cause anyone who makes even the slightest mention of a performance modifaction for the pilot gets flamed to no end or told they shoulda bought a different truck. guess there are no real car guys over there.
i couldnt agree more. most of my builds tend to be out of the norm. im finding i have to do alot of junkyard searching and scavanging to acomplish things on this one, but hey, thats half the fun. now that crv, that sounds interesting...
To anyone whom may be interested, I will soon have a fresh set of 62k mile j37a4 heads on the black market and then another set of 88k mile j37a2 heads maybe in another 2-3 weeks. I'm just chumming the waters just in case anyone may be looking. Both of these heads have the dual VTEC intake/exhaust which in fact DOES make a quite noticeable difference in both performance and sound! Never dyno'd my current setup before throwing the hairdryer on it but I suspected an easy 310whp with full intake and exhaust mods combined with an "edgy" tune by myself. The VTEC snaps in much more aggressively and carries this unique throaty sound that I LOVE. The only reason I'll be selling them is because I don't believe the single port heads are ideal for forced induction builds and will be switching over to multi port exhaust heads from a j32a2 here very shortly. PM me if anybody has interest.
To anyone whom may be interested, I will soon have a fresh set of 62k mile j37a4 heads on the black market and then another set of 88k mile j37a2 heads maybe in another 2-3 weeks. I'm just chumming the waters just in case anyone may be looking. Both of these heads have the dual VTEC intake/exhaust which in fact DOES make a quite noticeable difference in both performance and sound! Never dyno'd my current setup before throwing the hairdryer on it but I suspected an easy 310whp with full intake and exhaust mods combined with an "edgy" tune by myself. The VTEC snaps in much more aggressively and carries this unique throaty sound that I LOVE. The only reason I'll be selling them is because I don't believe the single port heads are ideal for forced induction builds and will be switching over to multi port exhaust heads from a j32a2 here very shortly. PM me if anybody has interest.
ok now i need a napkin for cleanup, i just hope i can get some fundage together in time before someone snatches these up. these heads are hard to come by used. been looking at junkers and salvage accross the country with little luck, or i find on half or both when i have no money. but awesome for giving us the heads up
Hey, i joined up here just specifically to give you this tip and see if it might help. Im in the process of buidling my J35z in mu '11 pilot and ran across this thread. What alot of us over on piloteers.org did to disable the VCM was to put a 100 ohm resistor inline of one of the wires of engine coolant sensor #2 (the one by the thermostat, not the one in the radiator). this makes the ecu think the engine is running a little colder than it is and vcm only works when the engine is at normal operating temperature. you will notice a slight decrease on your temp gauge, but the warning system is still hooked into ect#1 so you wont have to worry about not knowing if you over heat, eitherway, you would still see your needle climbing. hope this helps. that damn VCM was a thorn in my side from day one. ill be following this thread, its sad that i cant go on a forum for my own truck for info cause anyone who makes even the slightest mention of a performance modifaction for the pilot gets flamed to no end or told they shoulda bought a different truck. guess there are no real car guys over there.
i also forgot to mention, that with vcm dissabled, the non performance guys have noticed an INCREASE in fuel economy and there is definatly much better drivablility thats for sure
After reading more through this thread, I realize I asked I question that I already knew the answer to.
However, I wanted to clarify that I would need the J37a1 valve covers?
if i knew the answer more difinitively i would have answered, but this is my first venture in the world of honda building, ive built strictly chevy's and high performance marine outboards before this
Yes but there's one oil drain hole that does not align properly. The most sensible method of correcting this problem would be to have to misaligned portion filled in with aluminum using a welder, it's actually (IMO) more of a hassle because then one must have the heads resurfaced due to the height of the excess material added and/or the warpage caused from the heat during the process of welding. A simpler method of approach would be simply to thread in a plug into the misaligned portion of the drain and using a smidge of Hondabond to seal the mating surfaces on that area. The second method is the one I'm actually doing for the j32a2 head swap I'm doing for my built j35z3 motor going in within a few weeks.
Originally Posted by SykVSyx
After reading more through this thread, I realize I asked I question that I already knew the answer to.
However, I wanted to clarify that I would need the J37a1 valve covers?
If using the j37a2 or j37a4 heads, I'm quite certain that MUST use the valve covers that originally for these heads as they have appropriate height to clear the massive height and complexity of the valvetrain setup. Though there are some others I've seen that might fit their abnormal height, I'd play it safe and go with the original ones. Btw, the first set of heads I sold would come with their own original set so buyer need not worry about this.
Originally Posted by The Mental Mechanic
hey yungone, are you running the intake spacer like the mdx's have? if so which gen spacer the gen one or the gen two?
While I'm not running the mdx spacer on my setup, I am running a custom PTFE Teflon 1.90" spacer I made but its sole purpose was not for clearance issues from the manifold and valve covers but for a more obvious purpose: Heat. My intake temps were being murdered from the extreme engine bay temps due to the turbo setup. Just by adding the spacer alone allowed me to shave off on easy 10 degrees from post intercooler temps. That was BEFORE adding water/meth injection into the mix also.
Another good thing about the j37a2 and j37a4 heads I noticed during my NA stint was how well they allowed the engine to run more aggressive tuning than previous as the added lift and duration on the exhaust during VTEC really helped evacuate heat in the chambers. Though I never confirmed, I bet this would be a greater advantage for those experimenting (or wanting to experiment) with nitrous. The greater the exhaust flow the better as nitrous expels enormous amounts of exhaust gases out in comparison to the denser and cooler (thus less volume) incoming air charge the engine receives. Small exhaust cams or lobe profiles as well as restricted exhaust systems really impact the engines ability to perform its best on spray.
Yes but there's one oil drain hole that does not align properly. The most sensible method of correcting this problem would be to have to misaligned portion filled in with aluminum using a welder, it's actually (IMO) more of a hassle because then one must have the heads resurfaced due to the height of the excess material added and/or the warpage caused from the heat during the process of welding. A simpler method of approach would be simply to thread in a plug into the misaligned portion of the drain and using a smidge of Hondabond to seal the mating surfaces on that area. The second method is the one I'm actually doing for the j32a2 head swap I'm doing for my built j35z3 motor going in within a few weeks.
If using the j37a2 or j37a4 heads, I'm quite certain that MUST use the valve covers that originally for these heads as they have appropriate height to clear the massive height and complexity of the valvetrain setup. Though there are some others I've seen that might fit their abnormal height, I'd play it safe and go with the original ones. Btw, the first set of heads I sold would come with their own original set so buyer need not worry about this.
While I'm not running the mdx spacer on my setup, I am running a custom PTFE Teflon 1.90" spacer I made but its sole purpose was not for clearance issues from the manifold and valve covers but for a more obvious purpose: Heat. My intake temps were being murdered from the extreme engine bay temps due to the turbo setup. Just by adding the spacer alone allowed me to shave off on easy 10 degrees from post intercooler temps. That was BEFORE adding water/meth injection into the mix also.
Another good thing about the j37a2 and j37a4 heads I noticed during my NA stint was how well they allowed the engine to run more aggressive tuning than previous as the added lift and duration on the exhaust during VTEC really helped evacuate heat in the chambers. Though I never confirmed, I bet this would be a greater advantage for those experimenting (or wanting to experiment) with nitrous. The greater the exhaust flow the better as nitrous expels enormous amounts of exhaust gases out in comparison to the denser and cooler (thus less volume) incoming air charge the engine receives. Small exhaust cams or lobe profiles as well as restricted exhaust systems really impact the engines ability to perform its best on spray.
nitrous is something i have thought about, but have not run since i threw a rod in my z24 cavalier i had a few years back. but that was my own fault . On the issue we are having with our computers running the vtec with our j35z's, would the aem FIC be of assistance in the matter or would a standalone ecu be the only option here. was even thinking maybe one of the old buddy club v-cons, i dunno, just throwin spaghetti against the wall here
Robert, appreciate the thorough response, thank you.
Curious about something else, of course I will need the necessary gaskets for all the J37 parts, however, what about the bolts/washers/O-rings, all the little bits and pieces.
Can those parts be reused from the donor engine(j35), or should I just replace everything related to the J37 parts, I will be using?
I don't think I saw you mentioned, since I am doing a J37 build, should the heads be ported as well, even though they are already J37 heads?
honestly, if your going through all the trouble of removing the heads in the first place, might as well get some studs for the heads while your at it, that way they are there if you ever feel like going the turbo route in the future if for nothing else. and i wouldnt bother with porting, your getting enough extra airflow as it is, and probobly be maxing out the duty cycle of the injectors. any more you will be needing at least some rdx injectors and some sort of ecu managment to control them
Originally Posted by SykVSyx
Robert, appreciate the thorough response, thank you.
Curious about something else, of course I will need the necessary gaskets for all the J37 parts, however, what about the bolts/washers/O-rings, all the little bits and pieces.
Can those parts be reused from the donor engine(j35), or should I just replace everything related to the J37 parts, I will be using?
I don't think I saw you mentioned, since I am doing a J37 build, should the heads be ported as well, even though they are already J37 heads?
Funny you should mention RDX injectors.....I actually have a set of those to use and Scion adaptors to make them work. I am keeping the car an auto (yeah, yeah), so, other than using the stock Type S ECU('03 TL Type S A-Spec), wasn't planning to do any tuning. Not sure that I will need to, but open to know if that is the right call to tune or not.
No plans to boost it, it will be strictly a N/A build.
I would think it wouldn't make sense to port the J37 heads, since that is the goal I am trying to attain anyway.
As for the IM, I was planning to use the one from the J35, or will I have to swap to the newer IM, as well?
A ton of questions, I know, but trying to make sure I do this right, from the get go.
Yes, only one vtec spool assy., and one oil pressure switch.
My OE is VCM, so I have an ECU that is VCM with a corresponding VCM harness. Due to the fact, both my heads, each have 3 SWITCHES! lol
It's a little more complicated for me.
Oil pressure switch, I have two, so I'll need to combine them and bring them down to the new one-pin, on the Oil filter housing.
Same thing with VTEC wiring, combine, and bring it down.
Problem is, I have a third switch, Rocker Arm Control Solenoid.
The ECU senses low throttle, and engages the rocker arm control solenoid, creating hydraulic pressure, locking the zero-lift lobe on the rocker into action. Creating no lift on the respective ECO cylinder valves.
I need to find out if with KTuner, I can still send spark and fuel to those cylinders. Technically, the cylinder is in free-float when this happens.
I know on 8th Gen Accord ECU's KTuner can't disable VCM yet, but can it at least send spark and fuel, I'll disable VCM by getting rid of the heads! lol.
Still looking into everything, but I did drop off the heads to get fixed up.
I really don't want to have to use a different ECU
Maybe if you used a non vcm ECU that had support for K Tuner that might be your best bet.
Robert, appreciate the thorough response, thank you.
Curious about something else, of course I will need the necessary gaskets for all the J37 parts, however, what about the bolts/washers/O-rings, all the little bits and pieces.
Can those parts be reused from the donor engine(j35), or should I just replace everything related to the J37 parts, I will be using?
I don't think I saw you mentioned, since I am doing a J37 build, should the heads be ported as well, even though they are already J37 heads?
I'd use your engines original head gaskets as they are responsible for regulating coolant flow based off of the water pumps flow rate as well as the blocks internal coolant passage designs (there are slight variations in the j-series that ultimately determine piston to cylinder clearances based on target heat ranges). Though the j37 heads have increased volume in the water jackets, you don't want them creating issues with the engine warm up time by using the j37 gaskets which allow more coolant flow to the head. There is absolutely no advantage to this as many assume. Not unless the lower coolant temps are tuned for by altering closed loop-ECT initiation values.
Lastly, I highly recommend replacing your oil pumps oil relief valve (and spring) to one from the j37a2 or j37a4. This is because the dual VTEC heads will demand increased oil volume/pressure to actuate the rockers. Remember, these heads have a whole other rocker "rack" (exhaust side) to send oil down through during VTEC engagement. It's a very easy job as it only requires th removal of the oil pan to do. From there it's just a matter of unscrewing an allen headed bolt and then replacing it with another and then re-torquing it to spec.
Lastly, I highly recommend replacing your oil pumps oil relief valve (and spring) to one from the j37a2 or j37a4. This is because the dual VTEC heads will demand increased oil volume/pressure to actuate the rockers. Remember, these heads have a whole other rocker "rack" (exhaust side) to send oil down through during VTEC engagement. It's a very easy job as it only requires th removal of the oil pan to do. From there it's just a matter of unscrewing an allen headed bolt and then replacing it with another and then re-torquing it to spec.
Just to add to this. I did some research and the relief valve is the same for the J37a2, J35a8 RL & J32a3. The J32a2 does not share the same part though.
The springs and locking bolts are what's different.
Just to add to this. I did some research and the relief valve is the same for the J37a2, J35a8 RL & J32a3. The J32a2 does not share the same part though.
The springs and locking bolts are what's different.
you wouldnt happen to have part numbers off hand would you? if not, ill go do some digging
Yes, only one vtec spool assy., and one oil pressure switch.
My OE is VCM, so I have an ECU that is VCM with a corresponding VCM harness. Due to the fact, both my heads, each have 3 SWITCHES! lol
It's a little more complicated for me.
Oil pressure switch, I have two, so I'll need to combine them and bring them down to the new one-pin, on the Oil filter housing.
Same thing with VTEC wiring, combine, and bring it down.
Problem is, I have a third switch, Rocker Arm Control Solenoid.
The ECU senses low throttle, and engages the rocker arm control solenoid, creating hydraulic pressure, locking the zero-lift lobe on the rocker into action. Creating no lift on the respective ECO cylinder valves.
I need to find out if with KTuner, I can still send spark and fuel to those cylinders. Technically, the cylinder is in free-float when this happens.
I know on 8th Gen Accord ECU's KTuner can't disable VCM yet, but can it at least send spark and fuel, I'll disable VCM by getting rid of the heads! lol.
Still looking into everything, but I did drop off the heads to get fixed up.
I really don't want to have to use a different ECU
quick question, are you combining all of this and bringing it down to the same oil switch your installing on the filter housing?
While the relief valves are the same, it is the spring that controls the pressure correct? So with it being a different part number for the spring than one would want to switch it out?
.
. On the issue we are having with our computers running the vtec with our j35z's, would the aem FIC be of assistance in the matter or would a standalone ecu be the only option here. was even thinking maybe one of the old buddy club v-cons, i dunno, just throwin spaghetti against the wall here
