Wowsy, Just started reading all of Sashas threads. This one turned reckless with all the stupid dyno talk. I actually know Sasha and have done most of the work to my car with him. Gotta say the guy is stand up, definitely honest and also hardworking.
For all you dyno doubters. my car was recently dyno'd at SG (maybe sasha still has the readout, cause i dont) . It dyno'd at 260 rwhp.
my car has jwt intake, jwt flywheel and clutch, 5'16 spacer and mrev, nismo headers, pulleys, fast intentions HFC and exhaust and UPrev tuned. basically every single bolt on and it dyno'd at 260 rwhp. before the tune i believe it dyno'd at like 245 or around there. Dyno numbers are meaningless, unless they are used for comparison purposes.

The info on this thread is like priceless right now.

 

the primaries are stepped, starting from smaller at the head, and expanding in diameter as they continue, and exit with 2.5 inch outlets

 

do you know what size they are? and engine with this cylinder displacement and this size cams will usually make more mid to top end with a 1 7/8" off the head stepped to 2", sometimes 2 1/8". If the primary length is too short then it will suffer some low end power loss, but if it is say, 26" then there should be no low end power loss, and possibly some bottom end gain as well. I know building a set of headers for most people isnt the easiest thing to do, let alone installing them in a Z is not a 1hr job, but just something to think about with the larger cams. I am just stating this from all of my personal experience building and designing headers over the years for many many different cars/engines/setups and I am in no way telling you to do this, just sharing some thoughts on possibly extracting more power with those big cams.

 

On the racecar I'm currently running 1 3/4" to 1 7/8" to 2". On the headers we sell they step to 1 7/8" only.

The head ports are so tiny that coming off directly any larger than 1 3/4" is going to be a huge step. I have a hunch that once I port the heads you might be right about starting the primaries at 1 7/8".

We found about 10whp gain from the 1 5/8" / 1 3/4" headers, with mild losses below 4000rpm.

 

so much good info, thank you sash

 

understood, and you're right, header building is one part math, one part trial and error and one part intuition (all within the confines of what you can actually fit).

on my setup though, I am running comparitively 'mild' cams (not nearly as much duration and nowhere near the lift), and my headers are completely different (longer overall as I recall, but no stepped primaries and only a 2.25 inch outlet vs the 2.5 used here)

 

some of the crazier engine builds i've done headers for are all over the place just by playing with the collector diameter. A lot of the 4 cylinder setups ( high HP honda and nissan) are very very sensitive to collector choke diameter... Most of the SR20's make more power with a 2.25" choke compared to a 2.375-2.5" ( more everywhere, even at 8000rpms), and the honda's, same displacement, can be, and usually are backwards, where the 2.375 will make sometimes 20whp over the 2.25" even though they are making the same HP and TQ as the nissan...

Again, this is time and a lot of R&D and trial and error... Luckily those setups are easier to test and compare headers and parts and swap out easier than a 350z.... The cam test shootout was a lot of work, but a header test and R&D to get it all figured out, now thats a lot of work. Best bet to do that is probably with a "test" chassis where you have no front wheels or frame so you can get to the headers and all the bolts without obstruction.

 

I don't doubt it - you've got alot going on at that area between the pulses, resonance. It's akin to designing a good speaker enclosure. That was what I was saying above that bigger isn't always better. Often, it's just bigger, and can even be worse. Everything has a sweet spot.

We had a set of headers selected back when I picked my cams in 2005, and at the time, the cams I have were Tomei's most aggressive offering believe it or not. I bought 3 or 4 different sets of cams from various manufacturers, sent them all up to my engine builder and he knew what I wanted out of the car, and he made the selection. I ended up changing my header choice when a set of Crawfords came available, and luckily, they still worked well with the cam selection. If I did it again, I'd probably opt for a more custom setup, but time will tell, nothing I plan for at the present time since it involves alot of time that I just don't have, and I prefer to just drive it at this point.

 

I hear ya there! I wish i could have my car assembled and driving.. lucky bastard!

Oh, and I have one of your engine shots as one of my wallpapers... as i'm sure many many others do too...

 

The research has already been done...

https://my350z.com/forum/7435408-post15.html

 

I have been following all this from the start, and am still waiting for an available intake/throttle body that can deliver the air. I have a DE with standard intake mods and a free flowing exhaust albeit shorty headers. Even with JWT C2 cams and a solid UTEC tune, I am barely scraping 262whp/253 tq. on a dynapack. I have to wonder how much gain is coming strictly from your custom intake, and how much comes from the headers. Even if we could purchase those amazing headers, I fear that those of us without engineering and fabricating means to do an intake might have trouble making good power from the headers. Having just dumped $2500 into the car for 10-15 WHP, I'm a little disillusioned and broke. Getting 300 whp seems an impossible task, and 320 untouchable.

Thanks so much for proving what can be done. At least somebody is making power, even if it is costing a bloody fortune. Until I can get my hands on an intake that provides SG flow, the headers are a pipe dream.

 

Where are you in AZ? Tim at Xact in Tempe got 271/262 out of my car and I have no internal mods.

 

If your UTEC doesn't do cam control, and/or you don't have the ECU tuned for those cams, you'll be easilly leaving 10-15whp on the table with aftermarket cams.

We've seen the stock intake flow air, it just acts like a restrictor. You need to remember that pro racing series are making upwards of 500hp with restrictors much smaller than our intake system.

I would expect with your setup you should be around 275whp or so, and I bet theres a lot left in getting the cams setup right, perhaps in the mixure and ignition timing as well.

We will be hesitant to put money into developing products if the products we've already developed, that have proven to make power, don't sell first. I know that a proven package that makes 300whp is what everyone wants, and we will get there very soon. So hang in there

 

I'm getting ready to rebuild my oil consuming engine. I would love to use your 300 hp "kit" and help support your research!

Can you give details (cost, parts etc)

Thanks!

 

I'm interested to know what kind of gains were found in that tuning? Where did you baseline before the tune?

 

The stock intake and throttle body on a Z are not the issue on your setup...they are more than large enough. On my setup, I stayed with a stock throttle body and stock upper plenum with a tiny spacer for a long time. Swapping them out gave me a better overall curve from around 7k to redline (stayed flat, no dips like my previous runs had). Again, no one part, or pair of parts is going to magically wake things up - it takes the careful planning and tuning of the correct combo of parts. It's based on it working together. A huge throttle body sounds great in theory, but unless you've got the intake manifold that can take advantage of the flow (while not slowing down velocity), the cams that can actually inhale all that extra air, and the exhaust to exhale it, it just becomes a part to list in your signature...and nothing else. In other words, 'it takes a village'

As far as cam timing, it depends on the cams (and other things). I know on mine (non revup), going from a utec (no cam tuning possible) to a Haltech, I saw very minomal gains from tuning cam timing...a bit of fattening of the mid range but it wasn't dramatic) All depends on what the cams were designed around in the first place, and the rest of the setup.

For the umpteenth time, comparing dyno A with dyno B without having at least one car on both dynos (to see how they may be different) is really useless. The only truly valid comparison is your baseline curve to your end result curve, on the same dyno

 

Yes, I tried not to get too worried about dyno to dyno results. The tuning change from my street tune to UMS's dyno tune showed solid gains of 10-15 whp from 4000 rpm to redline at 6800. I was pretty happy that they showed me what I was doing wrong! From no cams and HFCs, stock Y pipe to cams, test pipes, XYZ pipe with HFC, and HR headers showed moderate losses under 4000 rpm and a total gain mentioned above, not accounting for dyno variance.

I was expecting 275 whp, and was pretty disappointed. UMS is a very reputable shop, so I don't think they left much on the table. I will have to figure out what part is the "village idiot"!

 

^ What was your reasoning for using HR headers?

Have the HR headers or y-pipe shown to make more power than its respective DE counterparts?

 

according to some, hr y-pipe gives good gains vs using the DE y-pipe. I tried this and after tuning the car, there was a rough a rough gain of about 2whp. I'll try to look for my dyno sheets and scan them.

 

2whp is def in the zone of negligable. I didnt think anyone would go to all that trouble with how much of a pain headers are on these cars.