VQ40 block swap in VQ35HR Z
05-13-2009, 07:40 AM
#1
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VQ40 block swap in VQ35HR Z
Looking at a piston speed calculator, the VQ37 has an 86mm stroke, and a 4288 FPS piston speed at 7600 RPM. The VQ40 uses a 92mm stroke and has the same piston speed at 7100.
So if you reduce the RPMS by 500 (say 7000 rev limiter instead of 7500) you achieve the same piston speed as a VQ37 at stock fuel cut.
Could we just swap the 4.0 block and put back the engine in the car with VQ35HR heads-cams-ECU. The stock ECU would still think it is running a stock VQ35HR.
We could take advantage of the better heads and cams of the HR on the 4.0 block since it only has mild cams and a 9.7:1 compression ratio stock.
How high a compression would installing stock VQ35HR heads on a stock VQ40DE block give us? The VQ40 has the same new 6 bolt main tall block design and uses the same transmission bellhousing as the VQ35HR and VQ37HR.
So if you reduce the RPMS by 500 (say 7000 rev limiter instead of 7500) you achieve the same piston speed as a VQ37 at stock fuel cut.
Could we just swap the 4.0 block and put back the engine in the car with VQ35HR heads-cams-ECU. The stock ECU would still think it is running a stock VQ35HR.
We could take advantage of the better heads and cams of the HR on the 4.0 block since it only has mild cams and a 9.7:1 compression ratio stock.
How high a compression would installing stock VQ35HR heads on a stock VQ40DE block give us? The VQ40 has the same new 6 bolt main tall block design and uses the same transmission bellhousing as the VQ35HR and VQ37HR.
Last edited by JClaw; 05-13-2009 at 09:08 AM.
05-13-2009, 08:28 AM
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you're taking a rather large leap of faith that the heads even bolt up, that deck heights are the same, that piston/valve clearances are remotely in spec. This is dismissing for a second motor mounts lining up, bell housing mounting to the block, clutches/flywheels being compatible, etc.
You're also taking a possible leap of faith that the rod and pistons from the 4.0 are of the same quality as the HR
not to mention, how much power do you think .3 liters of displacement is going to give you? more torque, possibly assuming they bolt together in the first place, depending upon the variants above.
I suspect its one of those things that sounds cooler on paper than it does if it were executed
One more thing...you're now asking your stroked engine to work well with the same cams as it had on a non stroked engine....begs the question of why?
You're also taking a possible leap of faith that the rod and pistons from the 4.0 are of the same quality as the HR
not to mention, how much power do you think .3 liters of displacement is going to give you? more torque, possibly assuming they bolt together in the first place, depending upon the variants above.
I suspect its one of those things that sounds cooler on paper than it does if it were executed
One more thing...you're now asking your stroked engine to work well with the same cams as it had on a non stroked engine....begs the question of why?
Last edited by Z1 Performance; 05-13-2009 at 08:58 AM.
05-13-2009, 08:41 AM
#6
you're taking a rather large leap of faith that the heads even bolt up, that deck heights are the same, that piston/valve clearances are remotely in spec. This is dismissing for a second motor mounts lining up, bell housing mounting to the block, clutches/flywheels being compatible, etc.
You're also taking a possible leap of faith that the rod and pistons from the 4.0 are of the same quality as the HR
not to mention, how much power do you think .2 liters of displacement is going to give you? more torque, possibly assuming they bolt together in the first place, depending upon the variants above.
I suspect its one of those things that sounds cooler on paper than it does if it were executed
You're also taking a possible leap of faith that the rod and pistons from the 4.0 are of the same quality as the HR
not to mention, how much power do you think .2 liters of displacement is going to give you? more torque, possibly assuming they bolt together in the first place, depending upon the variants above.
I suspect its one of those things that sounds cooler on paper than it does if it were executed
...and back to reality.
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05-13-2009, 09:10 AM
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05-13-2009, 09:19 AM
#10
you're taking a rather large leap of faith that the heads even bolt up, that deck heights are the same, that piston/valve clearances are remotely in spec. This is dismissing for a second motor mounts lining up, bell housing mounting to the block, clutches/flywheels being compatible, etc.
You're also taking a possible leap of faith that the rod and pistons from the 4.0 are of the same quality as the HR
not to mention, how much power do you think .3 liters of displacement is going to give you? more torque, possibly assuming they bolt together in the first place, depending upon the variants above.
I suspect its one of those things that sounds cooler on paper than it does if it were executed
One more thing...you're now asking your stroked engine to work well with the same cams as it had on a non stroked engine....begs the question of why?
You're also taking a possible leap of faith that the rod and pistons from the 4.0 are of the same quality as the HR
not to mention, how much power do you think .3 liters of displacement is going to give you? more torque, possibly assuming they bolt together in the first place, depending upon the variants above.
I suspect its one of those things that sounds cooler on paper than it does if it were executed
One more thing...you're now asking your stroked engine to work well with the same cams as it had on a non stroked engine....begs the question of why?
05-13-2009, 10:41 AM
#12
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^^^
lol
OP, why don't you try it...sounds good like most said, just need a test mule to excute this theory...
you'd be out $500 probably lose a weekend, but we'd have an answer...
lol
OP, why don't you try it...sounds good like most said, just need a test mule to excute this theory...
you'd be out $500 probably lose a weekend, but we'd have an answer...
05-13-2009, 06:07 PM
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you're taking a rather large leap of faith that the heads even bolt up, that deck heights are the same, that piston/valve clearances are remotely in spec. This is dismissing for a second motor mounts lining up, bell housing mounting to the block, clutches/flywheels being compatible, etc.
You're also taking a possible leap of faith that the rod and pistons from the 4.0 are of the same quality as the HR
not to mention, how much power do you think .3 liters of displacement is going to give you? more torque, possibly assuming they bolt together in the first place, depending upon the variants above.
I suspect its one of those things that sounds cooler on paper than it does if it were executed
One more thing...you're now asking your stroked engine to work well with the same cams as it had on a non stroked engine....begs the question of why?
You're also taking a possible leap of faith that the rod and pistons from the 4.0 are of the same quality as the HR
not to mention, how much power do you think .3 liters of displacement is going to give you? more torque, possibly assuming they bolt together in the first place, depending upon the variants above.
I suspect its one of those things that sounds cooler on paper than it does if it were executed
One more thing...you're now asking your stroked engine to work well with the same cams as it had on a non stroked engine....begs the question of why?
I think the idea sounds fine to me. Nissan has been renown for having interchangeable parts from multiple different motors. It would only be fitting. (pun intended)
This is the same reaction people gave when the debate about the possibility of a 1.5 JZ Frankenstein for Toyota's came to life. (1JZ head on a 2JZ bottom end)
I think its very probable that the motors would share parts.
05-14-2009, 02:33 AM
#14
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For a decent read. Talks about the VQ40 and VQ35. To the OP I only said that the 4.0 stroker kit would be a better option since it's brand new, etc. After you factor in the 350Z's wiring and compare it to the VQ40 it would be alot more than just swapping a block or heads. In my original post before the edit, I mentioned basically to make it work the best way possible. Piggy back ecu, complete wire harness from both vehicles, and you would most likely have to tap and drill holes into the block since I'm sure the 350Z uses more cooling in the heads/block since it's built for track and performance.
http://www.frontyspot.com/frontier/v....php?f=3&t=608
http://www.frontyspot.com/frontier/v....php?f=3&t=608
06-25-2009, 05:45 PM
#15
I had this same idea recently for my non rev up. A friend of mine here used to be a big honda guy. He mentioned that most honda engines have the same molding cast to keep the price down for the company. He mentioned that they would swap head with different honda engines. I was calling around today to see if it was a clean swap. I wouldn't know why not really .. I looked at a friends Nissan xtera and engine looks exactly the same. I think the problem would be matching the tranny.
07-03-2009, 08:45 PM
#16
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it has been mine (and the frontier community in general) that the HR block and the VQ40 block are the same (not the same as the older VQ35DE block, upgraded coolant and oil passages). the heads are also the same from what research i have seen (we've had a few guys take their engines apart so far). also, 350z cams fit in our heads with no modifications. the nismo (and stock Z) thermostat also fits. the pistons are the same size but are a different compression ratio and the rest of the rotating assembly (crank and rods) are where the extra stoke length come from. so if you were to swap in a vq40 "block" it would be the same thing that you already have (again, from what i've heard).what you are looking for is the crank and rods, but as the others have said, buying a proper stroker kit with better rods would be good since while the crankshaft is forged in both the VQ35HR and VQ40DE, the rods are not and are the weaker link and usual suspect when there is internal engine issues
07-20-2009, 09:10 AM
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I had the same thoughts as j claw i just picked up a nismo z with bad motor so i have a back up motor with all the parts to make one now i just need to find a vq40, I used too have one in my garage till i had a fire and its almost identical too the vq35hr.
07-21-2009, 08:02 PM
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i might be going off topic here a little but honda guys have been doing this for years. taking a b20 crank and putting it into a b18 block and creating a stoked motor for less $$$$$