3.7 double vtec heads on a 3.0 block - Honda Accord Forum : V6 Performance Accord Forums
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Old January 24th, 2015, 12:29 AM   #1
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3.7 double vtec heads on a 3.0 block

FWD N.A class's displacement limit is 3.0.

Only the 3.7 has vtec for both intake and exhaust, which I'm assuming is significant upgrade and not just economy b.s.

Do the heads bolt right up? Or is it a H-series head on F-series block ordeal, where it can be done but it's a PITA, and its more trouble than its worth?

I'm thinking a sub-ton 5th generation civic with a j30 would dominate, still looking into what the competition would be though.
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Old January 24th, 2015, 06:45 AM   #2
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They will bolt up to a J30A4 or A5 but will have to use the J37 head gaskets.
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Old January 24th, 2015, 09:01 AM   #3
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^ they will bolt up but will both Vtec sides function? He will also have overhang in the CC chamber will the heads being 90mm to the 86mm J30 piston. You can always mill the heads to shrink the combustion chamber, it will also bump compression.

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Old January 24th, 2015, 09:06 AM   #4
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I believe you have to shim the oil pump to bump pressure to support those heads.
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Old January 24th, 2015, 07:03 PM   #5
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The dual VTEC is still controlled by a single solenoid, it is the VCM heads that actually have 2 solenoids on each head and none on the oil filter foot. Yes there is 2mm of overhang all the way around which is why the J37 head gaskets must be used, as for the 2mm combustion carbon will fill that in quickly. The oil pump gears are the same size for ALL J oil pumps and the only valve to possible shim is the 90PSI pressure relief valve and since it is a over pressure valve, no need to shim. I was hoping for a upgraded pump on the J37A2 I just tore down out of a 09 RL, but nope......
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Old January 24th, 2015, 08:46 PM   #6
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^ Interesting
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Old January 25th, 2015, 05:50 AM   #7
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These are the heads I plan on using for my engine I am planning, pushing the J block to it's limit on displacement.....
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Old January 25th, 2015, 07:29 AM   #8
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These are the heads I plan on using for my engine I am planning, pushing the J block to it's limit on displacement.....
Nice to see you are still exploring the J series.

Does the J37 head flow more than say the J32A3 or J35A8 heads?
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Old January 25th, 2015, 08:20 AM   #9
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Hopefully we get a build thread on the J37. So is it going to be a J37a1 with Dual Vtec J37a2 heads?
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Old January 25th, 2015, 03:06 PM   #10
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I still have some builds I need to complete that I owe people then I will document the J37A2 heads, port the crap out of them and temporarily toss them on a J36 until my other short block is ready. And displacement will exceed 3.7L.......
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Old January 25th, 2015, 03:34 PM   #11
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I still have some builds I need to complete that I owe people then I will document the J37A2 heads, port the crap out of them and temporarily toss them on a J36 until my other short block is ready. And displacement will exceed 3.7L.......
Cool! I thought Honda maxed the block out with the J37 90mm bore pistons
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Old January 25th, 2015, 03:34 PM   #12
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Are they better than the j32a2 heads with a custom long tube header?
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Old January 25th, 2015, 03:46 PM   #13
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Cool! I thought Honda maxed the block out with the J37 90mm bore pistons
With stock sleeves, yes, 90mm is max
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Old January 25th, 2015, 03:51 PM   #14
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Are they better than the j32a2 heads with a custom long tube header?
Don't know yet, they are the wider runner intake ports which I like and the larger exhaust port like the 8th gen. Use the same springs as the 07 TLS heads, combustion chambers are "cleaner", cams are very different lobe setup to allow for the exhaust VTEC and that is all I can tell you for now until I tear them down probably next month.
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Old January 30th, 2015, 04:22 PM   #15
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^glad to see this. Hopefully this can help spark some renewed interest in these extreme builds.

And sorry guys, I'm one of the reasons he's not working on this right now...
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Old January 30th, 2015, 05:23 PM   #16
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^ You need your $hit fixed, right So you stick with the M90 set up or going all motor?
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Old January 30th, 2015, 06:19 PM   #17
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The new J36 is sitting in her now. Picking the car up Sunday. As of now it will stay NA a little longer...hoping to have a little change with the set up soon but I'll wait to see how things pan out before saying anything more. Needless to say, I plan on putting to use the new aftercooler and the added water/meth port so she will be seeing boost again...
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Old February 9th, 2015, 10:55 PM   #18
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The j37a2 and j37a4 engines have twice as many rockers to lock during VTEC engagement which means there's a higher demand for oil to be supplied to the top end. This means either the engine will require either additional pressure or volume (or both) to do its job. The RKG oil pump caries an oil pressure relief spring that's exclusive to the 09+ RL and TL 3.7's which also says that its design is unique and more than likely, with a purpose. Another thing is that HPD always installs the RKG oil pump from the j37a2/4 when they run the dual VTEC heads such as their SCCA race cars...every time.

Lastly, the j37a2/4 heads have identical intake/exhaust port sizes and shape to the RYE castings that were originally introduced in the 2007 MDX 3.7 of which, at the time, was the most powerful engine Honda made at 300hp. The tall and narrow "tumble" port intake design increases flow velocity which is great for throttle response, torque, and mixture suspension. Anyone remember what a tall/narrow intake port design did for GM on the gen 3 LS1 engine? It revolutionized production engine power for them...and all others who followed. Honda threw on these heads and made nearly 14hp just from the improved flow design. Its hard to argue against that IMO.

I've been running tumble port heads for a while now. And not just one set on one engine either. I've played around with head, cam, intake, exhaust, displacement combos like you wouldn't believe...both NA and FI applications. I can say without hesitation that its obvious the advantage they carry over the old port design.
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Old February 11th, 2015, 08:14 AM   #19
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Maybe this will spark someone to buy my J37a1 heads!
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Old February 11th, 2015, 08:49 PM   #20
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Loving the info..
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Old February 17th, 2015, 12:11 PM   #21
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So use the j37 gasket, throw em on a j30 or j32 bottom end & good to go for dyno tune w flashpro.....thats what this thread is confirming ?
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Old February 17th, 2015, 12:12 PM   #22
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probably recommend on a j32 or j35 bottom end since it will create a mushroom shape with a j30.
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Old February 17th, 2015, 12:14 PM   #23
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Dual Vtec you need to bump oil pressure to lock both sides. Youngone confirmed that. I believe outside of that everything should work

You can shave the heads .040" to eliminate the mushroom shape CC
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Old February 17th, 2015, 12:43 PM   #24
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probably recommend on a j32 or j35 bottom end since it will create a mushroom shape with a j30.
There is plenty of pressure already there and even the oil jets are the same part number.....
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Old February 17th, 2015, 12:55 PM   #25
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Well I have a j32 bottom end sitting in my car...after a 3rd to 2nd mishift (luckily I only bought the motor for 300). Opportunity is at hand instead of buying a j35a8 motor...props to this thread
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Old February 17th, 2015, 05:01 PM   #26
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If your boosting the J just get heads for the J32, or put a new valve's in the head. What exactly happened to the J32?

Your going to pay well in to $1,200+ just for the j35a8 engine.
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Old February 26th, 2015, 05:50 PM   #27
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3rd to 2nd misfit, j35a8 motor with 70k from an rl is $650 half Ur price stated
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Old February 27th, 2015, 09:39 AM   #28
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3rd to 2nd misfit, j35a8 motor with 70k from an rl is $650 half Ur price stated
You got a link to that?
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Old February 27th, 2015, 09:42 AM   #29
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You got a link to that?

Same source I paid $300 cash for my j32...they don't do online
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Old February 27th, 2015, 09:54 AM   #30
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i want a tl-s + tranney
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