You won't get a mean NA setup out of off the shelf parts.. I would have gone custom cams, pistons, full standalone, and custom fabricated ITBs w/ wire throttle.

And it seems like you had the dough to pull in a setup like that too.. I mean cosworth heads Should have squeezed some more juice out.

 

Bring it!! Cant wait to see it jeremy.

 

I wanted to do bigger cam grinds and pistons but I was afraid I just couldn't get good quality parts made correctly. I still may do full standalone...but I will do the Cosworth Intake and hopefully I can still make power past 6500 rpm. I know the 272 cams should make power to about 7500 rpm. Hopefully the motor will be back in and ready to start on Weds. Then its off to get painted and then tuned.

 

Sweet. Just say NAY to those who say "you should have done more" - or "wait until next month, until mine is done, blah, blah, blah" - major credit for work done, I like your reasoning on where you pulled back and where you didn't.

NICE!!!

 

valvetrain?

 

Its the valvetrain that came with the Cosworth heads...I think it they are Ferrera dual spring set with 1mm oversized valves.

 

I'm not sure you could have done much more for NA power. Nismo 284's are about the only cam larger than what you are running. Thanks for sharing the build pics, can't wait to see the wheel numbers you put out. Cam timing is a tricky issue, and what makes OEM high power cars like the GT3 so awesome. 415hp from 3.6L, and te timing and tune is the reason. Making that kind of NA power in the aftermarket just doesn't happen, it's too expensive to keep blowing up engines in the quest for a perfect tune. Of course, it is also what makes tuning NA so hard compared to FI, and really seperates the men from the boys in that regard. With that in mind, where did you get those cam phasing numbers. I would guess that if you could find the phase changes from a 996 GT3, (380 hp) then you would have a good idea on what to go by with your tune. The GT3 doesn't use VVL or anything tricky, just an aggressive cam with 52 degrees of total cam phase on the intake- similiar to what you have with the Nismo CVTC and your 272 cam. Just a thought. Good luck!
Will

 

+1 agreed. NA power > FI power. OP- seems like you are doing a great NA build-up. That cosworth plenum should really help when it comes out. However I think u should run some more agressive cams. U can get some middle processing/high lift Nismo cams with a working angle of 312 degrees and a lift of 14mm. Also I would suggest running some Crawford longtubes. Those should really shine better than the Nismo headers with your setup and possibly a 2.5 TD if the Nismo exhaust is not adequate but I am sure its more than enough. But with your current setup I predict 300+ whp NA. And dont listen to all the haters. Cant wait to see your dyno numbers and to see what she sounds like. Good luck.

 

WTF are u talking about? He is already running 272 cams. Maybe 1% of Z owners have those. More agressive than nismo r-tune, jwt s1,s2,c2 and tomei cams. And a v-pro/motec is needed for this setup. UTEC is not good enough.

 

Thanks for those that are offering encouragement. I post some pics of a real build that is taking months to complete and I get hated on. That is why alot of people don't really want to share any information that they discover doing projects like these. Its unfortunate because there is information that could help others that want to do a NA build.

Resolute, the VTC angles I posted were for the NISMO 276 duration intake cams. It came off a chart on the NISMO website. I am assuming those angles will be a good ball park to start with for my cams since my cams are 272's.

OK...here is my before dyno....if I can't gain 37 rwhp with the Cosworth intake and a tune I am going to be very disappointed. LOL Just playing...if I don't oh well...I least I learned a few things.

 

The FCON will not control the cam angles. The Motec and Hydra will, or a ecu reflash.

I have the JWT S7 Revup cams, 262 DEG DUR. / .450"(11.43MM) LIFT, More lift and a little less duration. The revup exhibts execlent idle quality due to the variable exhaust cam. I chose to use a utec because no software but the motec controls the exhaust camshaft. I plan on having Uprev reprogram the stock ecu for better cam timing once i am done with my turbo setup. I would really like some .520" lift cams with around a 300deg duration.

Places like Crane Cams can make you custom cams, any major camshaft company can do it.

 

I am tickled pink to see a build like this. Thank you for adding to the community. I've never seen anyone with the exact setup you are going with, and I bet no one else has either. How is anyone to say what will make the most power in conjunction with his other mods? You can't tell until he's done. I'm very excited to see the final result, dyno, 1/4, daily driving experience, autox or any other kind of test done to the car.
You ever think about going with the 3.9 FD?

 

Actually that is the next mod on my list with a LSD.

I am debating getting the FCON just for the timing and fuel and getting a flash to adjust the intake cam angles and idle. If not I will get a motec or I only need to adjust the VTC angle after 4000 rpm to redline. I didn't know about UpRev...I live close to them for so that might be another way to go.

Again...as far as bigger cams...I didn't want to be a the beta tester. The people I spoke to wanted me to give them all the cam data for both intake and exhaust cams. What the heck do I know about that?

 

A big reason why the new GT3 makes so much power is because it has a 12.0:1 compression ratio. In addition, your information is wrong the GT3 is equipped with VARIOcam variable valve timing.

I don't know if you have ever built or tuned an FI car before but FI cars are a lot harder to tune then NA cars because they are so fickle. A car with Forced Induction reacts way more to changes in temperature, altitude, etc. An NA car on the otherhand is much easier in those respects. If what you meant to say is it is much more difficult to get power out of an NA car then you are simply overstating the obvious.

With the compression ratio he is running it is very doubtful that he would be making enough power up top to be able to take full advantage of a set of 312 degree cams with that much lift. Not to mention those are custom grind cams made out of Nismo cam blanks. It does not seem like the OP is going for a custom set up as most of the parts he is using are "off the shelf." As far as longtubes the only company that I know of that currently offers a longtube header for the Z is XERD. Lastly, a true dual exhaust may not be the best option for this setup since it eliminates almost all back pressure. On an NA car some backpressure is a good thing and I personally think that the Nismo exhaust will be perfect for this setup.

Tomei has been offering 280 and 272 cams for a while now.

To the OP best of luck and I can't wait to see the results.

 

Hi Kwame,

I always felt back pressure was not a good thing for exhaust performance but of course there are many who say that it is.

Now that I am currently in the process of tuning an exhaust system on the dyno I wanted to test the hypothesis of "Naturally asperated HP and TQ as a function of exhaust back pressure"

I connected an electricly acuated buterfly valve to the back end of a Y pipe and hooked up a pressure sensor just upstream of the valve. The butterfly valve was adjusted to 0.25 psid increments at 5K RPM reference points.

I did several dyno runs at a range of increasing back pressure and measured the effect of back pressure on power and torque.

In conclusion, it was found that simple backpressure has absolutely no usefull purpose under any circumstance at any part of the curve.

As backpressure increased the entire power curve moved down.

So at this point we can put to rest the myth that back pressure has any beneficial effect on the VQ. I won't say that back pressure can't work differently on a different engine, but it certaintly didn't do any good on this engine.

Note: This is not to say larger diameter exhaust tubing is necessarily better. There are trades and compromises from going to large diameters to small diameters, but tube diameters ( or flow area) is more about its reactive scavenging effects rather than simple resistive losses.

 

+1 to the OP!

Can't wait to see the results. This is a rare opportunity to see the effect of internal mods on NA power.

 

Well it's the laws of physics that yield higher power with higher compression and higher duration and lift on cams. There's definately more left for NA power. I don't know what you mean by "blowing up" engines anyways.... A "perfect tune" for an aggressive NA buildup is totally achievable.

Just wanted to get what you were coming across..

 

+1 I have to go with Hydra on this one. I disagree backpressure is of total importance to an NA engine.

But then again if it's a streetcar a whole exhaust would be a good idea.

And a 312 cam would be great on a street car. I would love to drive on the highway with a power band up to 8k. Just because you get such an aggressive cam does not mean you're a slug in the lower rev range. IMO these are total misconceptions. To an extent getting nismo's VTC pulley would be a good idea to maximize efficiency throught the rev range.

 

lots of people confuse backpressure and exhaust velocity - the two are totally different

go too large on your exhaust on an NA car and you've killed your effective powerband. Get the primary and secondary diameters right and you'll be rewarded with a FAR more useable and FAR broader powerband. This is why header design is SO absolutely critical with real NA power, not to mention how those headers interacts with the cams becomes the primary factor in determining how the package all comes together

 

About time someone with some credibility said this. I get sick of reading "your exhaust needs some backpressure". It doesn't. The exhaust needs to maintain velocity like Z1 said. Backpressure bad, Velocity good.

OP, Good luck. thanks for letting us know what your up to, I look forward to your results. New intake, etc sound like some good info is on the way.