I've been kicking around the idea of putting the VQ40 crankshaft intoa customer's VQ30 block, for his turbo build.. Well, I went and priced the crank today at Nissan .. My cost is $215.00 for a brand new crank! We planned on getting pistons made for his 3 liter.. so, that's no problem. I am going to look at the VQ40 rods, to see how beefy they are.. If they aren't up the task, we might just get some forged rods made for it. This would yield a 3.8 liter motor with a 93mm bore/92mm stroke. Almost perfectly square.. It'll still rev to 8K without piston speed becoming a issue.. and should make a ton of power with the turbo. I'm going over it with the owner tonight.. If all goes well, I'll be posting pics soon..

Travis

 

Why are you going UP in displacement for a boost application?

The F/I section (where this post should be) will be able to answer any of your questions.

 

I bet the engine would blow when tuning on the dyno.

 

wow...215....are u sure??do you work at nissan because you said "your cost?"

also...how come a crank is worth less than a starter for a 4th gen?

 

"Why?" More displacement means more power under the curve, higher peak power, and more TQ, with a given turbo setup.

I think this could go in ANY forum, since this motor could be used N/A, or turbo.. I don't really have any questions.. I was just stating what I plan to do.. and thought you guys might be interested.

Travis

 

Care to share with us, how you came to this conclusion? I didn't know that certain bore/stroke engines would automatically "blow up" on the dyno...

Travis

 

No, I own a performance shop in Southern Louisiana.. The same shop that just finished building the 12 second VQ swapped B15 Sentra.. and the same shop that's building Frosty's turbo Maxima.

I'm not sure why the crank is so cheap.. I was amazed when he gave me the price. Retail was right at 300.00! I get a decent discount, because I do about 15-20K a year in parts through them. I know that a SR crank is twice as expensive.. I guess those "made in Mexico" crankshafts are cheap.

Travis

 

keep us update, if this works out there will be another potential engine hybrid to swap for FI setups.
BTW wats the VQ going into? another max or something different?

 

well it wouldnt. . . my comment was a joke but no one caught it.


but high compression and too much boost is a no no, no matter how your slice it.

 

When did he say he was making a high compressor motor?

 

It's going into a Maxima.. but I can't give out details until the car is done.. by order from the owner. I'll post details of the entire project when it's close to completion, though.. and I'll give updates on this engine if it does happen.

Travis

 

Oh.. I didn't catch the joke.. sorry..

We're having 9:1 forged pistons built for the engine.. so, changing the stroke means that we'll have to change the dish volume to get our target C/R.

Travis

 

..

 

wow i want to know how much that thing will put out without boost!

 

I am currently talking to a Sentra owner about doing the 4 liter bottom end, using a 3.5 liter block, and 4 liter internals.. As soon as I find out the combustion chamber volume on the 4 liter.. I'll figure out what the C/R will be. It will be all motor.. probably using stock VQ35 cams for now..

Travis

 

May the Tuner age rock on

 

OH

 

I bet a turboed stroker vq will equal pure insainity! Keep us updated. Since the vq40 was mentioned, how far fetched is the idea of stuffing one of those in a Maxima?

 

Well.. I haven't looked at the actual engine itself... but, I would think that the block/heads would be a lot like the 350Z VQ35DE.. However, there's nothing stopping you from buying crank/pistons/rods from the VQ40, and putting it into a VQ35DE block. I just have to check the combustion chamber volume and piston dish on each piston before I can say for certain what the C/R will be.

Travis

 

Putting a VQ40 crank into a VQ30 or VQ35 will raise the CR by quite a lot. You would need seriously dished pistons to get to a normal 10:1 ratio much less a more turbo ready CR. This would be especially true with the smaller CC of the VQ30 heads.

Just to let you Putting the VQ40 crank and rods in the VQ30 or VQ35 is physically impossible. The piston would literally be in the head. Some time ago a few people experimented on here to see about stroking the VQ30 with the VQ35 crank and rods and that didn't work. By the time you added the piston, rod, stroke, and everything else you would be something like .6mm into the head. Granted there are tolerances and you could build custom stuff, but would it be worth it then?

http://forums.maxima.org/showthread....highlight=VQ33
http://forums.maxima.org/showthread....highlight=VQ33
http://forums.maxima.org/showthread....highlight=VQ33
http://forums.maxima.org/showthread....highlight=VQ33 (specific on the VQ40)

Also the VQ40 short block is physically different from every other VQ. It is much larger to support the extra stroke. Even if you look at the VQ35 stroker kits you will see that they don't even approach the VQ40's stroke. The entire additional .5 liters from the VQ35 is from stroke, and the majority of the bump from VQ30 to VQ35 is stroke, .35 liters. Also how you would be able to make a stroked engine like that support 8k rpm is beyond me. I know you could do it, but it would be a feat.

It was a really good idea Travis and I can't blame you for trying, but I can't see this going far. Give me a call if you have any questions.

 

Well.. the pistons/rods, I planned on having made, of course. So, that's no problem. The block might have to be clearanced in a few spots, but I'm sure it would fit.

Also, about revving... Let's take a look at the SR20. This engine is revved to 8K all day long... some take it up to 9K with a solid lash adjuster and beefier springs. That engine is 86x86.. and it revs just fine. Also, there's guys with stroker kits, revving to 8K all day long. The Tomei stroker kit is a 92mm stroke.. and it revs just fine. Hell, I know DSM guys who rev 95mm stroke cranks up to 9K. Piston speeds on a 92mm stroke, at 8000rpm, isn't that bad. VE really doesn't matter up top in a turbo motor.. it doesn't care, because it's not relying on the piston to fill the cylinder.

I'm going to order a crank, and see how it fits in the VQ block. If it can be made to fit without much hassle.. I'd like to do it.

Travis

 

What kind of power would this monster have in a naturaly aspirated configuration? Nissan claims the new g35-6mt puts out 298hp at the crank. This 3.8L should at least match those numbers with a properly flowing intake to back it up

 

travis, whose car is this going in?

 

thank you SPIG!!! Its not going to work. The piston will come out of the block.

 

Did you miss the part about the custom rods?

 

Making a shorter rod would decrease the stroke right?

 

No, only the compression I think...

 

Search is your friend.

It wont fit.

This kinda belongs in the NA forum.

 

Changing the rod length changes the rod/stroke ratio. This changes the piston speed. The only thing that changes displacement, is the stroke of the crankshaft, and the bore size.

SR20DEN.. I searched a little, but couldn't find any hard facts on this. What makes it not fit? The bore centers are the same, the main's are the same size.. The snout is the same size/length.. Is it an issue of the crank striking the block? I ordered a crank just for the hell of it.. so I guess I'll find out soon enough.

Just wondering.. why does it belong in the N/A forum? I couldn't figure out where to put it.. technically, it would belong in a "Engine Tech" or "Technical" forum.. but, I couldn't find one.. so I figured "General" would be fine.

Also, it's kinda hard to search.. when you can't use the "search" function..

Travis

 

Change and new ideas scare people... especially the OGs here on maxima.org



carry on as planned, best of luck with this project

 

I know that my "credentials" here aren't really that well know.. and, hey, I should expect some people to doubt me.. Respect is earned.. I understand that. Ok, I searched around in Yahoo.. and found out some info that SR20DEN posted a while back.. about the differences in deck height, rod length, etc.. If I've done my math correctly.. with a few piston tricks.. I should be able to get yield this result..

Stroke- 92mm
Deck height- 215mm
Compression height- 23.5mm
Pin diameter- .790" (20mm diameter)
Rod length- 133.6mm

This would give a 3.8 liter, with a 1.45:1 R/S ratio. I am getting the extra rod length, by changing the compression height from ~31mm, down to 23.5mm (moving the pin up higher in the piston), and getting a tad more from making the pin diameter smaller.. allowing me to move the pin up a little higher, and make the center to center on the rod longer. I could offset grind the crank, and get a few more mm.. but, I'll settle for what it gives like this.

Now, before you guys go flying off the handle about the 1.45 rod ratio... let me explain a few things..

For a N/A motor, this would probably stink. As a matter of fact, it's almost the same as the QR25DE's rod ratio of 1.43:1. We all know that the QR has gobs of TQ, but is out of breath at around 5500rpm. So, N/A motor.. this probably wouldn't be a good idea..

Now, bolt a turbocharger on, and you change the rules. Since turbo engines don't realy on the piston completely to fill the cylinder.. you can get away with these kinds of ratios. I've built some turbocharged QR's.. and they hold power all the way out to 7200rpm, on stock cams. The midrange and low end is insane... the faster piston speed at low engine RPM, helps to get the turbocharger going (more exhaust pulses and more total mass flow at low RPM). The QR can spool a SC61 at around 2800rpm! Anyway.. what I'm getting at... is that this motor would make a HUGE, flat TQ curve, and could rev to around 7200-7500 safely. I think for a big HP turbo setup.. this engine would be awesome.

Anyway.. I'm sure opinions will fly.. but, I plan to do this.. I know it will work, based on other engines that I've worked on. Hell. DSM strokers are 1.4-1.5 R/S and rev to 9K turbo'd

Travis

 

The reason it belongs in the NA forum is because that's where discussions about changing of engine internals belongs, not that it isn't "allowed" in this forum, but the General forum and 1st through 6th gen forums are also known as the "ricer crap forum" for discussion of headlights and body kits and spoilers and "omg my battery is dead help!!11!111oneone!!1" discussions. Just look at the titles of the threads in this forum. "Need yellow headlights" "need wipers" "coolest mod" "front ashtray jammed" and the list goes on. Most of the people who have good amounts of technical knowledge on this board check these forums far far less than they check the N/A and FI forums.

 

Ahh.. I gotcha..

Maybe we can start a "Drivetrain Tech" forum? That would be a nice addition..

Travis

 

The main journal sizes arent even close to being the same (70mm vs. 60mm).

AEBS kept their maximum stroke to 90mm, which is even more than the JUN crank of 87.4mm. So a 92mm stroke might not even go in without notching the block, that is if you somehow got the block and crank mains machined enough to match.

The VQ40 block is alot taller than the other VQ blocks and even with the longer stroke it still has longer rods and a better rod ratio than the VQ35. The pistons are taller in the VQ40 than the VQ35.

A rod ratio of 1.45 is terrible and that is a very short lived engine on a good day.

After it is all said and done, you're looking at thousands of extra dollars in custom machine work, custrom pistons, custom rods and it's all going into an engine that won't last long at all if it does ever work. And using a crankshaft that probably wasn't designed to be revved very high.




Nismo sells a new VQ35 crankshaft for high rpm applications (8500+) which tells us that stock VQ35 crank really isn't supposed to be run that high (8000+). So I doubt the VQ40 crank is going to get along with high rpms coupled with a 1.45:1 rod ratio.

 

The FI. N2O and NA forums are all in the 'Advanced Performace' area, so I don't think we really need another forum. We almost have too mnay now.


If anything you would be better off using the 100mm Darton sleeves. Especially if you want a high rpm engine.

100 x 73.3 = 3454cc.

But considering costs there is almost no better option than spending $700 on a junkyard FWD VQ35. Part out the VQ30.

 

Ok, so you grind the crank to 60mm.. nothing hard there.. Also, I could offset grind the rod pins, and get it to a 90mm stroke. It would cost about 400.00 to grind the crank the way that I want.. so, that's still only 625.00 for a forged stroker crank.

If a 1.45 rod ratio motor won't last... then why is it that Nissan's QR25DE (1.43:1), works perfectly fine? I rev them to 7200 in turbo app's.. Here's a dyno chart from one that I built last year.. 18psi on a GT30R.

http://www.rs-enthalpy.com/images/dy...tec2-18psi.jpg

Now, granted, this is on stock camshafts and intake manifold... So, the TQ curve falls off up top. But, you get the idea.. this is a 1.43:1 rod ratio motor..

Travis

 

well, let's hope it works. it's always good to see such feat for the vq's community.
i'd give you a "yay" for doing this project.

 

***sits there jaw dropped*** i pray to god you get this project completed and all goes well! this sounds like something that... oh god already starting to get a hard on...

 

http://forums.maxima.org/showthread.php?t=363610


Yes, and I don't epxect a stressed out QR to last very long.

 

This thread is better off in the NA section, you'll get better responses.