I have seen many people say that the rods (and rod bolts) are the weak point in the VQ35. I was wondering, what would be the next weakest link that would need to be replaced before one could go high with HP?

Now, some will say lower compression pistons, I wouldn't want that. Now, forged pistons that keep the same compression (if available) would be nice. I really would like to keep the peepiness of the stock compression, instead of depending on boost more for most of the power and lowering the compression.

Running the higher compression would have less room for error, but as long as you run the same effective compression = (((boost/14.7)+1)*compression), it should be fine. Many engines are running on higher compression, they just can't take as much boost cause of their higher effective compression.

So those of you with a lot of personal experience with the engine, what else needs to be strengthened besides the rods???

 

pistons would be next, and most important, a good machinest who can balance it all well.

Pistons are actually quite easy to do- would take us about 4-6 weeks to machine a forged set that retains stock compression.

From there, in terms of power, its in the head, as it is with any car - the bottom end's job is to simply atay together

 

When I have a few grand lying around sometime within the next 50 years lol, I'm gonna go with new rods. I thought about pistons as well little_rod, but I dont' see any that retain the stock comp ratio just yet. Maybe Z1 performance can hook you up with a set, or the place that is selling the Tomei cams on the net that already have 8:1 or 11.5:1 can (both .20 over stock) can possibly do a stock yet forged set. I also wanna keep our stock ratio. Only difference is that I'll be going with Stillen rather than ATI or a turbo. The rods are like a grand, and probably atleast that if you don't swap them yourself

 

Man, making some pistons sounds expensive. What I don't know is the point at which you would need pistons also. For instance, if you switch rods, how much power can you go after that til you have some more problems???

Reason why I ask, if you replace the rods like when you go above like 400 rwhp, it would be nice to know what you need to replace as far as internals and at what power goal that would have to happen.

Now I know some of these twin turbo companies are coming out with stages for these engines as far as power (Cheston said something about this, speak up dude ). Hopefully they will include the internals that are needed at this power stage too, or at least let everyone (owners of the kit) know.

 

sgpracing.com has some high and low compression pistons for the VQ35DE's, depending on your application.

 

oil pump is def #2 after rods

 

dwnshift, are you saying a new oil pump with greater flow, and what about a oil cooler? Interesting you say that since you are pretty close to this engine, what makes you say that?

 

that just what i have been hearing....


if you want more RPMS....

 

RPMS???

 

revs

 

LOL, oh how sharp am I.

I don't think I would be looking to go higher in rpms cause of the way the engine is setup. Plus, you would probably have to add some more cams to do that also. I would rather strengthen things for boost, than extend anything.

Now this ain't saying I will do all of this, lol, just wondering.

 

Oil pump vanes are weak....there is something there to be gained.

 

The problem I get into is what is next weakest after the rods and what would have to be replaced to get to say 500rwhp+. That is not a nutty number, since most say that we can get to mid 400s without much problem on stock internals.

Once in a while on the dragstrip is different to me. I am more talking about on a safe daily driver. Most of these base TT kits that are coming out are boosting from 5.5 to maybe 10 psi and putting out like 334 to 450 rwhp. I just wonder what it would take to get that to like 500 rwhp+ besides rods without things getting too expensive.

 

Coming from a FI Honda background, at that HP level the cylinder walls need to be reinforced to prevent cylinder cracking, probably by sleeving. Pistons, rods and rings needs to be replaced. Your clutch will also be a weak point, and will need to be replaced.

 

But, you have to remember that the Z has 2 more cylinders - so 600 hp on a VQ35 would be like 400 hp on a B-series Honda. Not to mention Nissan has a habit of putting together pretty stout blocks since they have a history of so much forced induction.

One thing I would suggest though, if you're going to replace the rods, you might as well do the pistons at the same time. It really sucks to put some serious $$ into one part of the engine and then have the part you didn't upgrade fail and frag all those expensive aftermarket parts. Yeah, you'll spend an extra $1k for the pistons, but the peace of mind is priceless.

SC

 

Problem is where do you draw the line. If you are going to put in new rods, some say put in new pistons. Then if you are going to put in pistons, you just as well do cams. Then if you do cams, you just as well do sleeves. If you do sleeves, you just as well do retainers. If you do retainers, you just as well replace that oil pump. If you do an oil pump..................

You get my point, there has to be a stopping point somewhere, and that was the reason for my post. I know that you have to have a goal in order to know what to replace. If your goal is say 15 psi, which would put you right at 550 rwhp (for instance), what would be needed??

Now, 15psi might not get you to 550 rwhp, so you could use an exhaust, plenum, and such to help you get there. Does the engine need to be ready for the extra power given by these external mods?

Reason why I ask, these guys who are running a procharger on a stock engine, everything is fine. But if they add exhaust, straight pipes, headers, plenum, and such, do they need to make engine changes to make sure the engine can handle that power (my intution says no)???

 

Do they need to make changes? Hmm, depends. The stock internals may hold with the ProCharger but I am not holding my breath over the long run. For years my feeling has always been beef it where you can. I would definitely feel better on stock internals with head studs, main cap studs, connecting rod studs, better oil pump and a bigger radiatior to start.

 

Slightly off the subject, I've heard from a few road racers that the valve springs don't like higher than stock RPM's. Another weak link.

I KNOW we will SOON find out what breaks.......having adjustable boost, someone will very quickly find the breakable pieces.

 

making pistons really is not a big deal...pretty easily accomplished. How far you go will also depend very much on your intended head mods, as the two go hand in hand.

As for the oil pump, when we build a block, shimming the pump for added pressure across the board is one of those standard things. I ahve not looked into using a different one, though I am sure that can be accomplished as well (though I have yet to come across a motor that required a totally different pump).