LOL...posted in wrong thread.

 

Good results man, glad you had great success in your backyard build. As far as mine, iv got so far 1,000 miles on my backyard built motor too lol, looks like everything is perfect, after about 600miles i was no longer scared every time i turned on the car not knowing if it was going to blow up lol. thanx for ur tips man.

 

Ordered megan longtubes and just got off the phone with megs for a diy collector kit. Going to step them a little to 1.75" with a 2.5" collector exit. Will also be moving the O2 bungs down to the collector area. Anyone know where to get o2 harness extensions? I am doing this for the fun of it, if they work its going to be really fun.

 

Hopefully they stay in one piece for you......Be sure to let us know your thoughts and results when you get them on.

 

Just looked at your Dynos again, those are massive Torque gains for just changing the lower plenum and intake. By they way, what octane are you running on those dynos?

 

I will be taking measurements and pics, especially when I start cutting
92 octane pump gas, sometimes I will feel rich and go with 93. You have no idea the difference in feel between the two plenums.

I am hoping the headers will help my power after peak.

 

Have you thought about the cosworth intake manifold? Love your setup. Hope to copy it one day

 

I'd be surprised if on his set-up the cosworth made more power than his massaged plenums. He's put in the work with both rev-up and no-rev plenums. The cosworth is a great piece though.

 

the cosworh setup is designed for high rpm n/a and turbo use. his dyno shows power drop off after 7000 rpm. I'd be surprised if he didnt gain from it, with a tune ofcourse.

 

I'd be surprised if 264's even with the best flowing i/e would continue to make power over 7k. Unfortunately it's an expensive test. I think Adam (Z1auto) is putting one on his car and having it tested with his 268's. Should be interesting........the cosworth is absolutely worth it some cases.

 

If anyone cares to take the time, go on the cosworth site and print out the cam dyno test. They dynoed their 270 cams with and without their manifold and the results were very comparable to the revup lower below 6800rpm. I had to print them out and do some tracing. It looks delicious but I think the hang up right now is the headers. I am chasing the benchmark(Z1) although my torque curve is a little better the way his top end hp doesn't drop off like mine is just amazing. From what I have learned from research that can be headers. To clarify these will be only be megan long tubes 2/3 down the primary from there its getting bumped to 1.75" stainless and into a merge collector with a 2.5" outlet. The upstream o2 bung will be near the end of the collector which will require harness extenders. I will leave enough room between the y pipe flange and collector for a high flow cat in the future. As soon as I get them I will bolt them up to my extra long block and take pics. Just a little fyi porsche gt3 comes with 48mm primaries.

 

[IMG][/IMG]
They came..........
[IMG][/IMG]
nice 2.5" collector/outlets
[IMG][/IMG]
42mm piping
The primaries are a little over 30" long for the most part. The design in person does not lend itself to cutting up and reworking. So I will install them as is and dyno them.
[IMG][/IMG]
right collector
[IMG][/IMG]
left collector
The collectors are not very nice but I'll give them a shot.

 

What were the given specs......61mm is an odd collector size. Welds look a bit sloppy too, but if they work they work.

 

Its 2.5" od pipe for the collector as compared to 2.25" on the dc headers I have. I really want to do nicer collectors. I am very conflicted on chopping them up or just throwing them on and seeing if they work.

 

Amazing thread. Great job OP.

 

Had a day to roll around options of what to do with these things
1. By the time I go and make them a proper stepped header its going to get expensive
2.The collectors are just sh!tty can't live with them on the car

So I am going to order a merge collector kit from megs, transition cones ftw. If they come out real nice I think I will have them swain ceramic coated.
http://coneeng.com/exhaust_system_kits.html
I am going to lop off these "collectors" and make them look nice with the little merge bullets and then the outer collector which I will have to cut back for a 2.5" outlet. So the finished product will be these headers with "proper" merge collectors. I have established a budget of $600 so I spent $366 on the headers so I have $234 left. I was thinking about naming them the 666 headers but I am to cheap. As with the rest of my build its a build for the people with an eye on keeping it cheap.

 

I'm pretty certain the major reason the curve peaks so early on the DE motor is due to the intake runners being too narrow, especially around the curves. I would have to dig up the notes but I did some calculations when I had a Z a few years ago (and will pick one up again eventually...). According to what I have learned from reading SAE articles the flow through runners starts to choke when it reaches speeds of about 0.6 mach (local relative mach). The stock Z reaches that around 6200rpms, which is where it peaks with everyone that has stock runners. Even when everything else is mostly proper:


(rednezz Z)

I notice that Z1's car had a machinist work over the intake manifold (and is working over his new cosworth manifold to match it), that the cosworth engine (of top shop challenge fame) had a ported lower manifold on it's list of mods, and that ivory gt's car also bypasses that problem all together. In fact if you look at his comparison dynos of stock IM vs ITBS, sure the ITB's make power across the whole powerband, but you can see a point where the stock IM's runners are reaching choked flow and the itb's continue to climb:


(IvoryGT Z)

The HR intake manifold addressed the things that were the matter with what nissan attempted in the revup manifold, they maxed out the cross sectional area of the runners (in which geometry necessitated square runners), and the geometry/flowrate problem of the single TB design they had before.

Although longtubes will make an absolute difference in power, they are not going to reshape the curve to continue to climb. Look at SG's car, it makes much more power, but the shape of the curve looks exactly the same.

 

I won't disagree with any of that. I am looking to pick up power after peak I don't expect the peak to move. I just don't want the drop off I have now. If the merge collectors with transition cones work as advertised the scavenging effect/increased exhaust gas velocity will help top end power by optimizing the overlap period of the cam. These are not the end all be all headers, but I am going to make them perform the best 30" long 1 5/8" primaries can with nice collectors and ceramic coating. I use http://www.headerdesign.com/login/header.asp and play with variables. The primary length always falls around 30" but with larger primaries and collector. This setup I am constructing on that program is good for 325 flywheel hp. I know I ordered the collector kits today and I have to chop up new headers before they get here.

 

I follow everything you do, and I like what your doing. I've always like diy projects--especially ones that follow a budget similar to mine and you have made some solid numbers with what you've done. I'm excited to see what this header does on your car.

 

Let the nightmare begin....
[IMG][/IMG]
[IMG][/IMG]
The little ring of metal was how uneven the piping was as it was part of one of the primaries
[IMG][/IMG]
They aren't megans anymore.....
[IMG][/IMG]
If you look at the bottom tube and how it comes up short, so nice. At least the left side header looks like the pipes are somewhat even. I can't wait til my collector kit gets here, this is fun.