Upgraded Cast Iron mainfiolds?

[RickDLance]

To start with, just like headers there are good and bad *cough* stock *cough* logs. "Bad" not only because of the undersized cross sectional area, but the lack of steps, reverberation canceling, etc.

Now the header vs log debate. There have been a million studies done on this and results vary. As I've seen the results can easily be swayed in whatever direction the tester wants them to. You can match a great header with a horrible (cast or fabricated) log and vise-versa.

In my experience a well designed, equal length true header/merge collector setup will make more peak power. But it comes at a cost. A log will almost always carry more power under the curve and as a result is much easier to spool a big charger. The logs are great at retaining the thermal energy and produce a lot of velocity for the given size. If you want to make the absolute most power possible in a small rpm range then a tuned header works well. But in my opinion and experience a well designed log will give up a very very small bit of power up top (>5% in most cases) and give back much more everywhere else.

Thank You! Couldn't have said it better myself.

 

[hondarider552]

Those look good Brayden! :happy2:

 

[WolfLMM]

Rogue let me know when you are ready!

 

[Brayden]

Not trying to steal your thunder Rogue.. Lookin' good.

 

[ROGUE GTS]

Not trying to steal your thunder Rogue.. Lookin' good.

No worries. If it's something you want to pursue go for it, but I would go back and review the manifold design extensively. All the cost for the patterns you only get one shot at it. A lot can be gained from even learning from the stock casting.




Well guys I'm doing some more research on a few details and going to start modeling these up. Going to do some FEA and make sure there won't be any hidden internal tearing/cracking and we should be good to go.

I'm obviously planning to put a bung on them for a thermal/pressure sensor, but not sure where yet. Anyplace you would LIKE to see one? At the front near #1 or after the last port merge?

Also, how much do people open up the exhaust ports while doing headwork?

 

[racinmike77]

1 to two inches from where the last port merges and a drive pressure port would be nice also.

 

[Brayden]

Already done...

 

[SmokeShow]

port for each cyl./exh. port. :angel: j/k although some of the racers/pullers/high end builds may want that if they use actual datalogging equip. above and beyond what EFI Live can do.


Very cool what you are doing here... Initial thoughts on the increased size as far as flow capabilities?


c-ya

 

[mytmousemalibu]

Looks pretty sharp! I like em Rogue! Your too Brayden!

Just out of curiosity, what, how, why, do fabbed stainless units crack? More importantly, whats the trick to making ones that last a very long time, or never crack? Pre-heat or stress relive them?

 

[ROGUE GTS]

Looks pretty sharp! I like em Rogue! Your too Brayden!

Just out of curiosity, what, how, why, do fabbed stainless units crack? More importantly, whats the trick to making ones that last a very long time, or never crack? Pre-heat or stress relive them?

It's just in the nature of stainless, or at least when you use thinner material. 304/321 has a very high coefficient of thermal expansion. In an 18" section from ambient temp to very hot (glowing red in this use) those stainless pieces can grow almost 1/2" in length. And they grow in dia as well. That puts an immense amount of force on any welded joint and over time causes cracking.

Cast Iron is about 1/3 of that, and being all one solid structure makes it much more stable. Especially since (obviously) it was formed in a liquid and cooled/shrinks to it's final size. Providing the designer is experienced with castings and knows how to prevent internal metal tearing, and how to deal with frontal edge cooling, etc. They generally come out very very strong. But like anything, a novice trying to weld stainless will make a mess, someone who doesn't know the first thing about castings just trying to model up their idea of the internal structure will run into immense issues. Many won't be immediately apparent but rear their ugly head very quickly.

 

[WolfLMM]

Just another thought. My Z06 has two stamped halves that are welded together.

 

[Brayden]

Test fitted them today on the truck, and it's going to be a tight fit to get the v-band to work with a diamond eye downpipe .. larger downpipes may be an even bigger issue. I think I know how to fix it though.