I'm comparing intake plenum manifolds from both riffraff and irate.

Riffraff come in at $300
Riffraff Diesel Billet Intake Manifold Plenums - Riffraff Diesel Performance

Irate at $225
Buy Online | Irate Diesel Performance LLC

Any reason (from a product comparison's perspective) why I would choose spend an extra $75 for riffraff's product over Irate's? (All other company influences aside...)

 

It really comes down to quality. You can see it on the different links, but you can really notice it when they are in your hand. One costs about $75 to make and has worse flow/ more turbulence than stock. The other is a high-end engineered product that flows something like 19% better than stock, from what I remember when I bought mine.

I noticed that Beans has even stopped selling their billet plenums and are now selling Riffraff's, so that must say something as well.

http://bdpshop.com/riffraff-diesel-b...d-plenums.html

 

RiffRaff...

Quality product over a garbage piece of plate and tube.

 

Clay's also have O-rings so you don't have to use sealant. So I'd say it's your choice. I like the o-ring style myself.

 

I can't find a reason to justify spending hundreds of dollars for something that does nothing.......

 

If by nothing you mean you have a stock truck and aren't trying to get performance then maybe, except the oring seal is still a better design.

If you are trying to flow more then, aftermarket plenums are needed. But saying they do nothing is a ridiculous remark considering airflow is integral to performance at higher levels. Less restriction, more flow, better efficiency.

 

Increased airflow by replacing a tapered, smooth transition with a right angle through a flat plate? HA

 

Correct, except Riffraffs isn't flat on the underside, it's contoured for flow. They posted visual flow pictures for velocity and restriction a couple years ago on here. Look them up, or you could pony up and get a flow bench I guess. Why condemn something you aren't able to disprove. I think I will side with math instead of your hunch.

 

There's far more air flow restriction within the heads than there ever is at the plenum. Aftermarket plenums won't give you any additional power, and the stockers aren't restricting anything whatsoever. Free up the restriction at the heads first, then maybe there would be something left on the table with regards to feeding the heads.

And just to note, yes I have aftermarket plenums on my truck. Don't purchase them with the expectation of them to be any sort of performance enhancer.

 

Have yet to install them but they sure are nice!

X22

 

Actually that isn't correct, I'm sorry. While porting is always good, and can lead to flow gains, the intake runners can actually slightly out flow the plenum at high rpm. The largest restriction is the plenum mouth, not the head and not the plenum base.

 

After all my research and talking to many companies I am very happy I went with Riffraff, you can see and feel the quality and engineering. BUT, I wish I had snagged some blue ones 😎those look so nice!

 

There is no size increase going from stock to the aftermarket plenum. Still getting the same sized mouth. Same opening. Some even have a similar raised base as the stocker, such as the Riffraff one. So please explain in very precise detail exactly what has changed, other than the thickness of the metal itself?

Because nothing on the plenum itself changes what's underneath it.

I'm not knocking the product. It's nice. Just expect precisely zero improvements in performance from an otherwise perfectly functional stock plenum setup. Doesn't matter if it's a bone stock truck, or a 700hp beast.

Now if you've pinched the stocker and it no longer holds a seal because it's bent (which is quite easy to do), then yes fixing an existing boost leak with aftermarket plenums will bring back lost performance, efficiency, etc.

 

For me, my truck being an E99 these new Riffraff plenums are larger at the mouth my stock opening are (I believe) 2.5 inches where the new ones are 3". So I'm hoping to gain some better performance but that being said I do need to change the turbo up pipes and spider for it all to come together.
Sorry for not being much advice on the exact subject.

 

Hey Pocket, good to hear from you. The improvements are as you listed, they don't crush, warp or crack, and they don't blow the RTV out the bottom at higher boost like happened on my stockers.

Performance gained is in the flow, I will post it if I can find it again, but there is a flow map that shows the gain in the neck. I measured mine as well when I got them and the inside diameter was larger than stock. I think Riffraff posted something like 19% better flow over stock.