Trav4011

iTrader: (2)

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.

Anyway... just wanted to share this info.. I'll be posting pics/details of all the progress in the next few weeks..

Travis

Mike Wazowski

iTrader: (113)

very cool

altimateone

sounds like you did your homework! why not use the 3.5 block..pistons would probably be the same cost.. there's no replacement for displacement!
keep us posted

MIAPLAYA

iTrader: (3)

Travis has been in the business of building monster QR25s for the Sentra crowd for years now and does some AMAZING work. His latest project was stuffing a Maxima VQ35DE into a B15 Sentra. Glad to see some more stuff coming from you Trav. Can't wait to see some results...

Trav4011

iTrader: (2)

We plan on sleeving the block.. so, we'll probably just get a large bore sleeve.. since the VQ30/VQ35 blocks are identical except for the bore.

Travis

Trav4011

iTrader: (2)

Thanks man.. It's nice to finaly get somewhere... You know what I mean..


Travis

MIAPLAYA

iTrader: (3)

Sure do

ZON

iTrader: (2)

This is very interesting. Thank you Travis for sharing.

altimateone

thats works too.. even better!

thawk408

iTrader: (16)

So, are you saying that you have to move the rist pin up keep the stock compression? What if you wanted around a 11.5:1 compression, could you use the stock rods and pistons? Would the 92mm stroke be ok in an engine that will see 7000-7500 rpms, maybe even 8000? I thought about doing a stroker, but I read somewhere that the rod angle will be increased and that it will not be beneficial to higher rpm operation. Would you see more power out of stroking it to a 4.0 instead of just boring it to a 4.0, like using AEBS's sleeves? (sorry if this doesnt make sense or seems dumb, I am by no means an engine builder)

Trav4011

iTrader: (2)

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..

Travis

thawk408

iTrader: (16)

Whats the stock R/S ratio? Would stroking it give more power then just boring it out to the same displacement? My future plans are to build an NA monster, so this would for sure help.

MIAPLAYA

iTrader: (3)

Well unfortunately engine failures in the VQ have been all over the place. The generally accepted failure point is 450~ RWHP before the rods snap but some have been higher.

Zexy

iTrader: (55)

Very cool..So what kind of power are you looking with that setup?

Trav4011

iTrader: (2)

I'm going to do a all motor 4 liter to go into my S13 chassis... I was going to try the VK swap.. but, this is more feasible.. and it will allow me to test the stroker out in a daily driven vehicle. I am going to use a Maxima VQ35, because they're a LOT cheaper used than Z engines.. Plus, with all of the bolt-on's.. it makes almost the same power as the VQ in the Z. I think the highest whp I've seen on a N/A Z at 3.5 liters with every possible add on part, is 290whp. So, that's around 82.8whp per liter.. So, bumping up to 4 liters... I'd have to say around 325-330whp could be had, with current available mods. With some radical cams and headwork.. probably 350-375whp could be attained.

I'm going to do a 4 liter, with cams, and all of the bolt-on's.. and see what it does.. I'm also doing a 4.3 liter to go into a turbo maxima.. that'll be around 700whp when it's all said and done.

Travis

Trav4011

iTrader: (2)

Yeah... I've read about the stock rods failing.. I wonder if it's the bolts letting go.. or the rods themselves? So, for a N/A motor.. the lightweight stock rods would be optimal.. but, I wouldn't spray too much on top of that.

Travis

Trav4011

iTrader: (2)

The stock R/S ratio is 1.77:1. Which is a waste, for a motor that's only revving to 7K or so. the 1.59:1 ratio, would make for a lot better low end and TQ.. which makes for a fun street car.

Travis

Axelerate

iTrader: (19)

former Spec V owner and still a B15sentra.net member, so I'm subscribing since it's actually in my price range and I would love to make some cheap NA power.

Vamos_Rafael

iTrader: (18)

i think squeezing 350hp out of the 3.5 n/a is more important to me ...
efficiency > american brute force
2.0(s2k) makes as much hp power as a v8 mustang...

JERZ33

Travis, good to meet you. Build me on now, Ill pick it up in the morning...

Just playing. Please report your findings in this thread, Im subscribing in a BIG way. This sounds really solid.