Just wondering if an ECU upgrade could boost horsepower without any other mods. Everything I hear mentions that no upgrades are going to do much without it as the stock ECU will adapt and limit any changes. So it stands to reason that maybe it's already limiting the stock intake, exhaust, etc.

Thoughts?

 

yup, 33hp is a rumored number actually, might be more.

ECU will be a huge mod.

 

Yeah, ECU's are always a GREAT mod. Everyone always claims 33..same thing with my Acura. Hondata makes great ECU programs....The said around 33 also...Real world gains w/o mods was (I think) ~20hp. In conjunction with other mods, it added alot more. It voids the warranty though

 

I have a feeling the thing is quite tuned to the stock application. But I bet there will be some improvement. It sounds like Chebosto is trying to find out for us here. I know JWT is having a hard time with the ecu so it may not be that easy. I wish i had the tools and the know how to mess with it. If someone wants to give me a Consult II for a month I will be more than happy to be as unsuccessful as everyone else who has tried.

 

[QUOTE]Originally posted by VandyZ
[B]I have a feeling the thing is quite tuned to the stock application. But I bet there will be some improvement. [QUOTE]

Now that you say that, I think you're probably right. My reasoning for you being right is as follows:

There is no Z trim that adds performance (increased hp/tq). So it would benefit Nissan and their customers to tune it well. With my Acura, there was a plain RSX (5-speed, less HP, different parts), the RSX-S (6-speed, 200hp, etc.), then there was the type-r over in Japan. Had even higher hp, some better internals, etc. I also heard that Acura was planning on releasing a higher performance version of the RSX in years to come (prolly US version of the type-r). So I guess Honda/Acura had a reason to detune this engine. NOt to mention I have heard many say the the s2000 engine was similar to the RSX-S (s2000 has a larger throttle body, better cams, just better internals in general).

 

actually they may have detuned in with insurance in mind, as well as the certain reputation that a car gets when it can and does respond well to modification. think of the stigma the Z has when you tell people intakes and exhaust net no gains, they think 287 is it. but the idea of 30hp and then even more from other bold on mods gives the car "modability".

 

I seem to remember sometime back in the day - prerelease times - that Nissan of Japan was actually talking about how a sub 300hp car is different to insurers than a 300+hp car. That it can make a difference to customers that want to shill out the $$$ for the car that they aren't paying an extra $500/year for a 20hp increase. I'm pretty sure this has been floating around the rumor mill for quite a while, but I do know (a friend of mine is an economist for Chrysler) that car companies do look at what their vehicles will insure for because that can bias a buyer significantly.

 

I think that there is a strong possibility to boost the stock power at the top end. With the variable valve timing adjusted and the rev limiter bumped up a few hundred RPM there is certainly potential to increase power if the heads, intake & exhaust can keep flowing (and the rods, crank & pistons stay together).

At 6,600 RPM the VQs piston speed is a pretty conservative 3,525 feet per minute. 4000 feet per minute is generally considered the upper limit for most engines although race engines exceed this for (relatively) short periods of time. That means that 7500 RPM should be attainable with an aftermarket ECU. It may take a cam change and port job to get it to run strong up there but I'm hoping the variable valve timing is up to the job without all that.

I don't really think we will see much of an increase in peak torque and there may be a weakness in the engine that keeps us from reaching 7500 RPM reliably but I do think that we will find extra power through higher RPM.

 

I'm beginning to be skeptical about gains....

Since peak torque and HP is around 5k(right?) and you think we'll get gains around 6500-7500, it would make gains at that rpm range kinda pointless right? Or are you saying the gains will be all throughout the top end? Cuz otherwise, it's not really gonna do ANYTHING for straight lin performance...

Someone please educate me.


See, in my rsx-s the peak TQ and HP was almost right at redline. SO mods, and upgraded ecu's really did alot for the RSX-S. The ECU especially, because it raised the rev limiter to 8600 rpms! Since the Z engine isn't built that way, I just don't see how it could help straight line performance...

 

you might loose some low end, but less restrictive intake, exhaust, and headers, with a differnt timing up top could change the dyno curve significantly, most mods increase high end power.

 

As long as the torque does not completely drop off at higher RPMs (ie, the power can be maintained), then simply increasing the redline can often significantly help straight line accelleration because you can stay in the lower gear for longer periods. The VQ35 still makes peak power very close to redline, so even though the torque drops off rapidly at high RPM's, there's still probably another 500 RPM of headroom (maybe more) before you would need to shift. If you couple a higher RPM with some better headers and maybe some cam changes to get better breathing, then the power could be improved significantly.

I know I would be happy with a Z that could rev to 7500 RPM (since the shift light can be programmed to 8000, it should work just fine.... )

-D'oh!

 

All this ECU stuff reminds me of problems my brother was hearing about. He had a 95 BMW M3, which had OBDI, and thus they were able to reprogram his chip for some nice power gains. However after that BMW changed to OBDII and I still don't think tuners have been able to get reliable gains from them. Something about you can trick it a little and maybe get good power gains on one run, then OBDII figures out what's going on and re-defaults the values. It's basically always fighting what you're trying to do. And as the ECU programming gets more and more complex it gets harder and harder to crack the code and have it reliably produce HP. I hope someone figures it out b/c it's something that definitely needs to be addressed, it's just going to be a lot more difficult than most people believe. In this respect maybe some of the Japanese tuners that have a good relationship with the factory will be the best positioned to get the inside info and figure it all out.

Speaking of outputs, has anyone seen how Nissan is making ~340@7500 rpm for their R-tune car? I saw a Japanese page that had that listed. Wonder what they did to get that power?

 

The Z engine does make peak power near redline, the factory peak power rating is at 6200 RPM, redline is 6600. Power is torque times RPM (divided by the constant 5252). Torque is more complicated but it is basically a function of how much air you can get to flow through the engine per revolution. A chip won't help much in the areas where the combustion is already nearly optimum (like peak torque speed 4800), but if we can change the cam timing, raise the rev limiter & maybe add a little spark advance we can keep the same performance up to the current peak RPM (6200) and add substantially to the top end.

I don't know if the stock drop off in power above 6200 is due to the stock ECU limiting cam timing, spark & fuel or if it is due to mechanical design limits. I think this engine has the potential to run well on up. If we can get it to make the same torque it currently makes at 6200 RPM up at 7350 RPM it will go from 287 to 340 HP. Thats not likely because friction increases at higher engine speed. Still, the potential some more power is there, bring on the ECU's!!!

 

well the hondata ECU added a good deal of hp without any mods. With mods, it jacked up the HP quite nicely... I know there's room in the 350z for more performance, but because the peak power isn't near redlien, I think we'll see very minimal gains