I was curious to get some helpful feedback on how to increase my stroke. I have the vq30 and want to increase the stroke without paying *** loads of money to have a custom one made. Will any of the family of Nissan engine crankshafts swap rather easily? And what if any block clearence problems might I run into?

P.S. I've tried to research this on the net with little to no help(not very good web surfer). If anyone has a good souce of information then let me know. THANKS

 

I don't know for sure on this but I think that nissan designs their engine blocks with one size in mind. Therefore you might not be able to lengthen the stroke because the crank throw size would impact the engine block. If anyone else knows better please say so.

If it can be done though there are several things that you have to ask yourself here.

- can you do all the work and do you have the nessicary tools (and can you afford to have your car out of commision for a long time)

- Why do you need to lengthen the stroke? It will gove you an overall gain in power and torque because of the increased engine displacement, but there is more than one way to skin a cat, and changeing stroke is ALWAYS expensive.

 

Increasing stroke is just a piece in the puzzle my friend.

 

Good luck to you with the stroker...

It's probably not the easiest way to get power out of the vq.

What does the rest of the puzzle look like?

 

 

you do realize that you don't drive a honda right?

 

Honda's aren't the only motor you can stroke... Just my $0.02 but why don't you tell him why it can't be done rather than make fun of him?

 

As always Dan, you have a way of slappin down and bringin em right back for more

 

I forgive you 'DanNY', I realize not everyone can be as ignorant. Have a nice life.


Now, is there anybody that has some useful info or leads for me?
BTW, here's another one for the guru's. Do any of you know how many cfm's the regular intake can flow as opposed to the variable intake-(not the MEVI).

 

Probably the only crank that will give you a long stroke might be the 3.5 liter VQ. Or unless one of the other VQ or VQ friendly motors have rods that are longer.
You sure you want to do this? You questions indicate a lack of research so far.

 

Jeff, thank you for your imput. The rods are not the problem, right now anyway. The reason for the crank ? is to hopefully find some place or someone that can help me with the spec's.(diameter of crank journals, what the different crank will change the stroke to, etc.)
I'm trying to avoid fitment issues, such as the crank not clearing the block and the sorts. To answer your last sentences, i'm trying to find a source of knowledge to avoid problems down the road. If you look back to my P.S. on the first post I mentioned that i'm not very good at searching the web.--Mainly for highly specific data--more specifically, measurments of engine intenals and clearences
Just need some help, that's all. Thanks again

Please correct me if i'm wrong, but don't you increase the stroke by shortening the rods and increasing the cranks rotating circumference?

 

You need to understand what "stroke" is. Is the distance the piston travels from top/bottom or bottom/top. Whatever affects this distance will affect the stroke length. There are MANY ways to change the stroke. Also 3x more things to think about when you change it. Compression, rod/crank interference, valve relief, short end/big end bearing sizes, flywheel fitment concerns and so on and so on................ Don't know what I'm referring to here? Then I highly suggest you increase your knowlege before even THINKING of messing w/ this. Also reading about something is just ONE part of engine building. For every one thing you change, there are 5 things behind the scenes you have to now deal with. These things are not written along side of articles and one must know where to reference the info(ie.. OEM Nissan service manual, make's tech info etc....)

I bet you don't even have a OEM Nissan service manual?

 

I guess not

 

 

Am I the only one who is gonna comment on a guy asking for help on his stroke? Come on guys, I'm disappointed

 

Well now that search is working, there are a plethora of threads to reference on this topic. I remember SR20DEN, Nismo87se and Mardigrasmax going in depth on this particular topic.

Being that the VQ30DE and VQ35DE share the same lower block, it should not be too much of a struggle to use the VQ35 crank and rods in a VQ30. You will however, not be able to use the pistons, as the bore is larger in the 3.5

 

I heard of this guy who supposedly dropped a VQ off at a shop the other day....

 

Yup your right. Got beat on that one.

Well the guy asks some pretty techinical questions and then just disappears. Hard to know if he really wants to know or is just curious.

I just bumped up the thread to see if he would reply.

Thanks Chinkzilla, helpful as always.

 

Spoken like a man.

 

Chinkzilla is right. We've had a few topics here theorizing on a VQ hybrid. Theoretically, a VQ30 block with a VQ35 crank and rods would make a VQ33. It would have a lot of torque, but probably would not rev much.
I like the idea of using a VQ30 crank on a VQ35, destroking it to a VQ32. It'd be very oversquare, and quite revvy.

 

Just buy a VQ35 and get custom rods and pistons.

 

Sorry it took me a bit to get back to the thread. I was never alerted to any new post.


Jeff: Are you serious? I'm disappointed in your responses to say the least. You're a mod for cryin out loud. All I can say is whatever.


For those of you who are trying to help the feable minded here, thanks for your help so far.

KLoWn: I figured someone would try to bring some humor into the thread for some good laughs. Guess not, huh? If you got one let it rip.

Zilla: Thanks for your imput. It is much appreciated. If you can think of where I can find measurment and clearence specifics let me know. In the mean time all check into your suggestions.

BlackVQ: Also, thanks for your imput. Just I don't understand your term "oversquare". I understand the theory of a shorter stroke allowing the engine to rev quicker, but would a lightened crank have the same effect?

Mardi: It has crossed my mind, but I guess I like to do things the hard way. Not really, and that's a good suggestion. However, I have a spare 3.0 and wanted to work with what I have presently. I know you have done a lot of planning for your next project so you have some insight. Is the suggestion to go with the 3.5 made because of the simplicity, maybe more structurally rigid and better suited for FI applications, or probably the other dozen reason I couldn't think of? I'd like to get your feedback as to the reasoning for the suggestion. Thanks

To everyone: Thanks for the info so far and keep it coming. Also, if somebody comes up with either a web site or another way to get the really specific info i'm seeking please let us know.

 

If anything a VQ35 block would be less robust for FI applications being that it has a more aggressive bore than the VQ30 and therefore thinner cylinder walls. This can be remedied by cryo-treating and o-ringing the block etc. Nissan probably took this into consideration however and strengthened the internals to some degree.

Oversquare just means that the ratio of bore/stroke is tipped in favor of bore. Yes you are correct that it would make for a happier revving motor, as there is less piston travel per stroke. I believe most honda engines are designed like that. The shorter your stroke in relation to your bore however the more lateral piston motion there is per stroke, increasing the chance of piston slap. Therefore, clearance tolerances are reduced.

Lightening the crankshaft has it's advantages in that it reduces reciprocating weight, always a good thing, however the trade off is less tensile strenght in the crank.

Easiest path is what mardigrasmax suggested.

 

Yes, I hear you guys. I'm curious to find out why or how you come to that conclusion. I'm looking for the rational for that choice.

Thanks for the feedback

 

 

Too much to type. You need both FSMs, review them and compare.

 

The reason MardiGras recommended just going with a VQ35 and custom internals is that there will be less headaches. You won't have to worry about playing the "mix 'n match" game with other VQ parts. You'll be able to order the custom parts you need, and not only will they be cheaper than the OEM Nissan parts(if new), but they will likely be of better quality and better suited to your needs.

Since you've already got a VQ30, I guess you can just try and get the crank and rods from a VQ35. At the very least it would be cheaper than buying a new VQ35.
The other issue that comes up is what to do about the electronic throttle and CVTC on the VQ35. Did anyone ever come up with an alternative other than swapping a VQ30 head in place of the VQ35 unit? The resulting static compression ratio of 10.6:1 might be a little high for the tastes of some. I might be behind the loop on this one.

 

 

Also, for a given displacement, an oversquare engine will produce less torque than an undersquare configuration, but will rev higher (speaking in generalities, here). Honda engines are famous for being very high revving but suffering from lack of torque.

 

Really? The VQ30 is oversquare and makes quite a bit of torque. It's one of the few import engines that makes more torque than horsepower, the old fashioned way.
You did say 'generally speaking,' after all.

Not to get too OT, but I was thinking it'd be cool to see Nissan go to a VQ33 for the Frontier and XTerra. Nissan could probably afford to keep the engine NA and not worry about using a roots blower.

 

Yeah, but it would make even more torque if it was undersquare (at the expense of some horsepower, maybe). But I think Nissan got it right.

 

ATTENTION ALL MODERS

the first thing that you all need to realize is that no one who posts on maxima.org is going to be able to design an engine better than nissans engineers did.

Leave it alone. That is all you can do.
do you want me to give reasons? okay here we go:

- When balancing the primary and secondary force couples of a v6 engine (notice I only speak of force couples and not forces directly because the use of a 3 plane crank shaft eleminates all primary and secondary forces) the most widely accepted technique is the use of extended webs on each end of the crankshaft which counter all rocking and rotating force couples and cause the engine to be perfectly balenced. Thus when changing the crankshaft on one engie along with the rods and possibly the pistons you change the amount of weight that contributes to reciprocating forces. Thus the crank webs on each end of the shaft must be modified to accomodate the change in reciprocating mass. But this is a minor problem since even without extended crank webs the couples are maintainable with proper motor mount design so lets move on.

- the intake and exaust manifolds are designed to handle flow rates and speeds associated with one swept volume size. Changeing that size has a signifigant effect on the engines ability to create proper airflow turbulence and thus makes the combustion process less effective. It may in some cases require the retardation of spark timing to compensate for poor swirl or turbulence and mismatched cam profileing. Although the knock sensor and enging control unit will control the timing for you this retardation of the spark will cause some lowering of performance. The effect on exaust is usually negligable.

- Because of the above factors and many others that I can't even comprehend an engine with a modified stroke wil not be capable of lasting as long as a stock engine.

The maxima is fast, and fun, but it is not a race car. and that is not a bad thing.

 

 

The intention of modding an engine is rarely to make it last longer. There are always trade-offs involved. Everbody knows that.

 

 

I know, I just wanted to show off.

but it is true.