I won't say it's impossible but it's highly unlikely. The vq37vhr is putting out almost 90 horsepower per liter stock. LS motors don't come anywhere near that from the factory therefore they have more room to easily add horsepower. This is the biggest limiting factor in modifying the 370z for n/a. The vq35 is hard to even get to 300rwhp with full boltons and cams. The vq37hr has a definite advantage with vvel but no one knows yet what it's capable of I'm very optomistic about it. I don't know yet but I think 340rwhp is the limit with full boltons and a tune. High compression pistons won't give too much of a return considering your starting at 11-1 compression ratio and you will need race gas and engine longevity will be drastically cut. The heads already flow extremely well so a port and polish will help but results won't be drastic. If your shooting for 400rwhp n/a it's going to be very expensive and your engine won't last the life of the vehicle. I know you want to go n/a but FI is the better way to go. Many 350z's have been running for several years with superchargers and turbochargers putting down 400rwhp on the stock block. And the vq37vhr has been torn down and inspected by several shops and it has a proven stronger bottom end so I think it might even last the life of the vehicle at 400rwhp on the stock block. The cosworth engine is a bad benchmark to go by that's a race engine that would cost a lot to reproduce. Just so you know I'm a member over at my 350z so I have some background in the vq motors.

Great feedback
 

The more information I see, the more I think that 400 is unattainable without going turbo or using a supercharger.

So what is attainable with just bolt-on's??
 

I'm thinking mid-range numbers like 330 to 350 now.. Am I off base. I'm shooting for just bolt-on's.

I havent read the whole thread, but based on recent findings, I think 400NAHP is a dream on this car. I think we should aim for 300-320 at best.

Agreed. (That is until someone figures out how to tune the VVEL 100%)

My initial performance goal is 370hp at the flywheel, which should equate to about 315whp. I know this is easily possible with JUST high-flow cats, cat-back exhaust, and Cobb AccessPort Stage 2. The AP Stage 2 out for the G37 with this setup claims about 11% gain (about 38hp), so I expect the Z will have similar #s.

Adding an intake to this setup with a Stage 2+ tune would more than likely result in another 10-15hp gain, which brings flywheel horsepower close to 400 at the flywheel, but not quite. I think getting 400 even at the flywheel will be tough to do, but maybe with a plenum spacer, pullies, and some other stuff it will be possible. Now, 400whp, that is a whole other story. I honestly don't know if it's possible at all naturally aspirated without doing some major work.

I REALLY doubt that those mods gives you 40HP more at the crank...

Read the quote.

(Ignore the nitrous part) That's with basic boltons. I don't know what full boltons are to you but I/H/E and a tuned AP isn't much. ~350whp (or was it 340???). Anywho, they didn't push it on the tune so there's some more left. Also, there's a few more boltons they can add to that to increase the power.

What other boltons can be added to increase power? Intake manifold? Pulleys? What else? Ignition? Switching to E85?

I'm pretty sure no one even dared to think that I/H/E with a tuned AP would net anywhere near 90 whp above stock either. Never know until it's tested and tried...I'd like to see the outcome.

But 400 is a bit far fetched now that I think about it, lol.

Yeah. I think with I/H/E you'll see about 350 crank max until tuning becomes a science for this motor. VVEL is impressive, at the least, but imagining that you can tune out the equivalent to a mild cam, you can hit 400 crank and maybe even with a big cam-type tune, 400whp.

350 Crank!? That's obsurd...that would be a gain of 18 HP at the crank...intake alone is showing 18 at the wheels.

^ Do u really think an intake setup is gonna add 18 at the wheels? Lets wait for mass production and independent results before we start eating Stillens #'s. I dont doubt that their intake system performs, im sure it performs well, but im just a bit pesimistic on those claims.

Anyways i also am a member on my350 and guys with VQDE's and Revups all manage somewhere around 250-270whp on average with full bolt ons and their respective tunes. I have seen guys with 270-290 range with cams and head work and the only 300whp + NA ive seen is Adam's from Z1 but he has a fully built 3.5. Now the HR has been showing that it responds better to bolt ons because guys with 07-08 Z's are getting 300whp with a I/E setup. There is a guy with an auto 07 making 320whp with full bolt ons and TS reflash. Now the 3.7 also seems to respond well to bolt ons and im gonna go ahead and guestimate around 300-315whp with I/H/E setups and 320-330 with I/H/E/TP/pullies/tune setups. Now to go higher than that we are gonna need cams but someone needs to crack the VVEL on the intake side first. This is all speculation tho. We are just gonna have to wait and see until more parts come out and more people mod their cars. But i cant wait for that and cant wait to see what GTM, Technosqare, Top Secret, Amuse, and all the other compaines come up with. I hope that the 3.7 gets the same aftermarket support like the VQ35 did but seeing how compaines are going bankrupt and the value of the american dollar dropping, parts are gonna be harder to come by and more expensive...

^Yes, I really do. Stillen has been around for a long time, they have no reason to fudge numbers or out right lie, they service a niche market. My point was merely that 350 Crank HP was an absurdly low estimate for the mods listed, it would be a gain of only 18HP for I/H/E. Also, I would be weary of drawing parallels from the 35DE/HR to the 37VHR they act completely different regarding mods, as you yourself said. I'll stick by what I said earlier in this thread.

-CAI
-Header Back Exhaust
-Injectors
-Ignition (like the HKS DLI)
-Pulleys
-Aggressive Tune

Should Yield over 400 Crank or Near 350RWHP

Are you insane? You think you're going to pick up about 70HP to the wheels on intake and a header back? Keep dreaming my man.

-First, injectors - why? What for? You cant tell me the stockers are being pushed that far to their limit.
-Ignition - why? The stock system should work just fine with those mods as they are minimal.
-Pulleys - going to be MINIMAL gain seen from these.

This isnt Need for Speed: Underground here, dude. I bet people will be lucky to get maybe 310-320 to the wheels with a TOP QUALITY I/H/E setup and tune. Either way, you'll just be disappointed if you want to play the numbers game on this car, and drag it to a Mustang Dyno...which is where you should rightfully go for a tune, anyway.