I have joined this site to educate myself about the 350z. I am in the process of deciding between this car and the S2000. My question is this, what is the future of this engine? Is there quite a bit more HP in this engine to be found. I am talking more in the range of ECU and bolt on as opposed to FI......all intelligent comments are welcome......


If you want to bash the S2000 please spare me the BS. I know what the S is capable of and dont need to hear a bunch of "this is better then that"....thanks

 

The source of this information is from a very "automotive techno-geek" who owns his own dyno shop. (his dyno is used by Hondata for their R & D)

This guy knows his sh*t.

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Short of an F1 engine, nothing is ever maxed out, and even F1 engines get updated.

However, the VQ35DE in the Z is an interesting case. I certainly think it can see nice gains, but I don't think the gains will be all that large as some people might expect.

First of all, it runs a 10.3:1 compression ratio, so you could certainly bring it up a point or so. This would be worth about 2% in output on average.

Now, in order to increase output on a NA engine (w/o increasing displacement), you have to either improve torque output, or you have to produce torque higher in the rpm range (and/or rev the engine higher). So, if we look at the VQ35DE, what are the options?

Well, first of all, it doesn't really make sense to rev the Z higher in stock form. The torque curve takes a major dive after 5000 rpm. That doesn't mean that you couldn't rev the Z higher with the right mods. The stroke is less than 82 mm, so the piston speeds aren't exactly high (although I don't know the rod ratio). In order to facilitate higher revving, you'd need to replace the cams, which would almost certainly compromise the low end performance since the Z does not use a variable profile/lift setup like VTEC. However, if you're willing to live with that, you can move the power curve up. If you were to pick up an extra 20 lbs-ft of torque at 6500 rpm, you'd gain about 25 hp more. A significant gain, but it probably won't happen with bolt-ons.

In terms of overall efficiency of an engine, I like to look at torque output. For a production car on pump gas, its rare to see more than 80 lbs-ft of torque per liter of displacement. And in fact, the Z approaches that at nearly 79 lbs-ft/liter (more than the S2K's 76.5 lbs-ft/liter).

In terms of torque output, you could certainly pick up some gains with more compression and breathing mods, but those gains won't be huge (in fact, they might be smaller than on an S2K in terms of percentages). Also, the bore is quite large, which does not necessarily lend itself to high thermal efficiencies (although interestingly it should support large valves which could really produce high rpm flow and power).

I fully expect to see some mildly modded 350Z's pushing 320 hp all motor (maybe 265-275 whp), but that would be about the most I'd expect for a streetable setup. Compared to something like the 3.25 liter S54 I6 from BMW, the Z motor is not as revvable and does not appear to have anywhere near the top end flow capacity. For one, the VQ35 uses a variable path/capacity intake manifold. While such manifolds are terrific for low rpm and midrange performance, they almost universally compromise top end flow and power (the S54 uses individual throttle bodies in a large common plenum).

Conversely, we're already seeing S2000's pick up 15-20 hp with simple bolt-ons. And judging by the results available from the Mugen ECU and the AEM EMS, there are more gains to be had once a commonly available programmable S2K ECU becomes available (the key being timing changes). Then you've got compression, headwork and cams (the latter being the biggest factor IMO). But more importantly, the gains you achieve on the S2000 will come at higher rpms. If you achieve big gains at 8000 rpm on the F20C, vs. 6000 rpm on the VQ35, every lbs-ft of torque you gain will result in 1.5 hp on the F20C vs. 1.1 hp on the VQ35. That's significant.

In terms of practical applications, we have a large body of data to examine for the VQ market in the form of the Altima and Maxima. To date, these cars typically pick up around 20 whp from intake/exhaust/ypipe/underdrive pulleys. If the 350Z does as well (it could do better or worse, so far the exhaust results haven't been good, and some exhausts DECREASE hp) there won't be much left to modify unless you go internal.

So, in summary:

VQ35DE = good engine, possible 320hp N/A MAX
However, that's not much in the way of bolt on gains if Altima/Max are any indication
Multi-path manifold compromises high rpm gain potential
Head flow potential unknown

 

The analysis seems a bit biased towards the S2000 but that's expected.

Here's a few things that don't make sense about the analysis:

Regarding using cams to increase the high rpm torque and thus increase HP, the VQ can stand to lose some low rpm torque. It has plenty to spare. The S2000 OTOH already has a very peaky torque curve which would become even more peaky with an aggressive cam. VTEC would allow a very aggressive cam change while still being able to idle which is a good thing. However, you would have to increase the redline of the S2000 engine to take advantage of a highly aggressive cam profile. I don't know much about the engine but seems like it might be maxed out already at 9000.

Regarding the intake being a limiting factor for top end flow capacity, so what? Change the intake. He's talking about modding cars but seems to think that an intake manifold must be left in stock form. A good port job may be all that is needed but the aftermarket may offer something even better.

Bottom line, I don't see anything in his post describing the two engines that gives the S2000 any advantage for NA potential except for VTEC and I'm of the opinion that Honda has already used up most of the potential that VTEC offers in the stock engine design. I'd rather have the 1.5L of extra displacment. Really I'd like to have both, but finances start to get in the way.

 

Regardless of what type of car this person is for or against is irrelevant. This person seems to understand engines and the capacities that they possess. I enjoyed the post. Although I think I will take my Track Z and be happy with what Nissan gave me!!

Silverstone Track with all the toys

 

You are right. I know very little about the S2k engine. Do you have a torque curve plot that I can see? The drop off in the torque curve of the VQ near redline makes it a good candidate for cam work. It should show impressive gains and like I said the drop in torque at lower rpm's will be inconsequential since it has plenty to spare.

 

I know Im new to this site, but why does this topic ,and from what I have read quite a few others, turn into propaganda BS over the S2000 and the 350Z. The article stated you could pull 320 HP out of a NA 350Z, how is that biased toward the S2000. Even with the 20HP gain on the S, that still only puts it at 260HP. I dont think the article has to be biased one way or another. Why put a PRO Z slant on it just because it is on a Z site......by putting a pro Z slant on it all your doing is making the article BS.

I wish I would have gotten on this site earlier to see all these S2000 and 350Z arguements...

 

VTEC is variable timing and variable lift. CVTCS is just variable timing.