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jnaut · 05-15-2010, 09:56 AM

ok so i found this info...

VQ38/VQ40 strokers...

I thought I'd share this with the Z guys as well... I'm currently building a 3.8 liter stroker for a turbocharged 01 Maxima. We are using a VQ30DE block, however, if the 3.5 liter block was to be used, you'd have a 4 liter stroker, using the same crank/rods.. just slightly larger bore.. Here's the details..

The VQ40DE, used in the new Nissan Frontier, has a 92mm stroke! The deck height is much taller.. around 244mm, versus the VQ30/VQ35's 215mm deck height. So, it allows them to use a longer rod, and get a 1.8:1 rod/stroke ratio. By using the VQ40 crankshaft in the VQ30/VQ35 block, keeping the stock compression height.. would have to use a 138.9mm rod. That's 5.3mm shorter than the VQ35. This would yield a 1.51:1 rod/stroke ratio. Now.. if we were to use the stock 144.2mm rod, and move the wrist pin up 5.3mm in the piston.. we'd have a rod/stroke ratio of around 1.57:1. That's very acceptable.. For comparison, the SR20DET has a 1.59:1 R/S ratio.. we all know how capable that engine is.

So, say you want something better.. we use a smaller wrist pin, allowing us to move it up a little higher.. say, 2 more mm.. This would give us a 146.2mm rod, and yield a R/S ratio of 1.59:1.. same as a SR20. Since you are getting custom pistons made anyway.. you could get the pin where you want it, and whatever diameter you want. No big deal to go a tad smaller.. just use a thick tool steel pin (.140 wall) and you'd be fine.

Now, the cool part.. is what it would cost.. I did some research.. and found that the VQ40 crankshaft from Nissan is CHEAP! How cheap? Try 300.00 retail! It's forged, and very beefy.. The only downside, is that the main pins are 10mm larger in diameter. No big deal.. pay a good crank shop to grind it down to the VQ30/VQ35's 60mm diameter, and you're set. So, for around 500.00 you have a 92mm stroke! I went ahead and ordered a crank.. to modify, and check fitment.. I don't forsee and major block mods to get this to fit.. maybe some slight grinding for counterweight clearance.. Hell, you could knife-edge the counterweights, and not even have to clearance the block.

So, what's this cost?
VQ40 crank, cut down- 500.00ish..
Custom pistons- 750.00

That's around 1250.00 for a 4 liter stroker for the VQ35DE. If you stay N/A, the stock rods should be perfectly fine.. If you want big power... toss in some aftermarket forged pieces.. Hell, if you really wanted to go nuts.. do the 100mm bore, 92mm stroke... and you have yourself a 4.3 liter.

There's a lot of debate about rod/stroke ratio... Some would say that 1.75:1 is the "optimal" R/S ratio.. It just depends on what you want.. I think, that for a street driven car, around 1.6:1 is optimal.. It gives a good balance between top end, and low end/midrange TQ.

As for how high you could rev it.. the SR20 has a R/S ratio of 1.59:1.. people have taken them to 9K with solid lash adjusters.. I'd say that a 1.57:1 R/S ratio could easily rev to 8K safely.. I think with the right cams, a N/A monster could be had.. Of course, a turbo/super application would be the best, to take advantage of the increasein displacement. The TQ curve would be awesome.. You could use the 92mm crank, with stock rods, and move the pin up in the piston so that the rod would fit. That would be the best budget stroker kit.. and would be fine for up to 400whp or so.. You guys know what the VQ35 rods are good for..

05-15-2010, 09:56 AM	#10 (permalink)
jnaut A True Z Fanatic Join Date: Dec 2009 Location: wpb, fl Posts: 1,146 Drives: 09 370z Rep Power: 18	ok so i found this info... VQ38/VQ40 strokers... I thought I'd share this with the Z guys as well... I'm currently building a 3.8 liter stroker for a turbocharged 01 Maxima. We are using a VQ30DE block, however, if the 3.5 liter block was to be used, you'd have a 4 liter stroker, using the same crank/rods.. just slightly larger bore.. Here's the details.. The VQ40DE, used in the new Nissan Frontier, has a 92mm stroke! The deck height is much taller.. around 244mm, versus the VQ30/VQ35's 215mm deck height. So, it allows them to use a longer rod, and get a 1.8:1 rod/stroke ratio. By using the VQ40 crankshaft in the VQ30/VQ35 block, keeping the stock compression height.. would have to use a 138.9mm rod. That's 5.3mm shorter than the VQ35. This would yield a 1.51:1 rod/stroke ratio. Now.. if we were to use the stock 144.2mm rod, and move the wrist pin up 5.3mm in the piston.. we'd have a rod/stroke ratio of around 1.57:1. That's very acceptable.. For comparison, the SR20DET has a 1.59:1 R/S ratio.. we all know how capable that engine is. So, say you want something better.. we use a smaller wrist pin, allowing us to move it up a little higher.. say, 2 more mm.. This would give us a 146.2mm rod, and yield a R/S ratio of 1.59:1.. same as a SR20. Since you are getting custom pistons made anyway.. you could get the pin where you want it, and whatever diameter you want. No big deal to go a tad smaller.. just use a thick tool steel pin (.140 wall) and you'd be fine. Now, the cool part.. is what it would cost.. I did some research.. and found that the VQ40 crankshaft from Nissan is CHEAP! How cheap? Try 300.00 retail! It's forged, and very beefy.. The only downside, is that the main pins are 10mm larger in diameter. No big deal.. pay a good crank shop to grind it down to the VQ30/VQ35's 60mm diameter, and you're set. So, for around 500.00 you have a 92mm stroke! I went ahead and ordered a crank.. to modify, and check fitment.. I don't forsee and major block mods to get this to fit.. maybe some slight grinding for counterweight clearance.. Hell, you could knife-edge the counterweights, and not even have to clearance the block. So, what's this cost? VQ40 crank, cut down- 500.00ish.. Custom pistons- 750.00 That's around 1250.00 for a 4 liter stroker for the VQ35DE. If you stay N/A, the stock rods should be perfectly fine.. If you want big power... toss in some aftermarket forged pieces.. Hell, if you really wanted to go nuts.. do the 100mm bore, 92mm stroke... and you have yourself a 4.3 liter. There's a lot of debate about rod/stroke ratio... Some would say that 1.75:1 is the "optimal" R/S ratio.. It just depends on what you want.. I think, that for a street driven car, around 1.6:1 is optimal.. It gives a good balance between top end, and low end/midrange TQ. As for how high you could rev it.. the SR20 has a R/S ratio of 1.59:1.. people have taken them to 9K with solid lash adjusters.. I'd say that a 1.57:1 R/S ratio could easily rev to 8K safely.. I think with the right cams, a N/A monster could be had.. Of course, a turbo/super application would be the best, to take advantage of the increasein displacement. The TQ curve would be awesome.. You could use the 92mm crank, with stock rods, and move the pin up in the piston so that the rod would fit. That would be the best budget stroker kit.. and would be fine for up to 400whp or so.. You guys know what the VQ35 rods are good for.. __________________ Best 1/4 mile 12.24 Best mph 114.5_______