Someone needs to test it.

If the square top manifold gives a healthy increase to a stock engine then the Honda intake could only be better again (im talking high revs). Sure, you need big cams, valves and lots of head work and free exhaust flow to really unlock the power but the stock intake is still restrictive at high revs. You might loose some low - mid range torque but the engine will be able to breathe up high.

 

The future is now people.


This manifold is confusing.

 

So, what are we look'in at here?
Brand? Runner length? It looks like the plenum can seperate from the runners. Throttle body?

 

Skunk2 ultra street b series honda manifold reflanged for bp. 64mm skunk2 miata tb.

 

Nice work... I'm very interested to see how it goes. From the pic it looks like the throttle body is welded on or is that an adapter plate? I can see its on a 45 degree angle which will help with clearance between the tps and chassis.

 

I have an adapter plate for the bp throttle body welded on but rotated to clear the hood. I have a second upper plenum to out the alpha 70mm honda throttle body later once I get the megasquirt on.

 

If you are dynoing it, I would really like to see if there is any difference between the 64mm and 70mm tb. I would bet there wouldn't be much in it but it would be nice to know for sure at least at one data point.

I've moved to a s90 70mm tb now which is 100 x better than the skunk2. I was getting leaks through the throttle plate which could wiggle a few mm making idle inconsistent and the tps to throttle shaft connector first came loose then failed entirely.

 

Ill see what I can do. Is the s90 tb the same bolt pattern? I need to figure out my idle motor setup with the new throttle body.

 

Just use the Honda idle valve on the plenum.

 

Key to making that short runner manifold work is full race cams. Like way past STL and into EP territory. Madjak talks about how simple it is but he's talking about a full race motor that lives above 8000rpm, makle crap power below 4000, requires at least 100 octane and probably idles above 1500rpm. While exciting and interesting, that is probably only relevant to like 12 people in the US. The other tens of thousands of Miata owners would like something that makes more power from 4000-7500, idles pretty much like stock and runs on pump gas. The key delineator here is cams. .500 lift, 290° duration in the case of the short runner 200whp beast, more like .420 lift, 260° duration in the case of the 165whp pump gas daily.

The Skunk2 manifold is sized for the big cams and 200whp. Again, interesting from a purely academic perspective but personally, I'm far more interested in a long runner manifold to pick up where the squaretop leaves off.

 

I'm going to have to put it on a dyno because I honestly feel an increase in torque below 4k from the vics manifold. And I confirmed it was working fine prior.

That is what is confusing about it. I expected massive loss down low, but that didn't happen. Manifold is getting milled and ported now, so I will have more than initial perceptions soon.

 

Read through this entire thread today from start to finish, a lot of information. The thread peaked, then died off. One thing i did notice was about 4 different people promise aftermarket intake manifolds for us and yet literally the only option that came of any of it was BEGI redesigning their existing manifold with noone else making any head way. The thread is over 5yrs old lol.

Several people have posted cnc head flanges, but are these available from anyone? Someone mentioned a CAD file for a head flange, but never listed it. Ive searched for it a bit with no luck if anyone can share.

Seems like the ultimate conclusion is go custom sheet metal or have the welds crack frequently on the honda conversion manifold. Are there any threads with legitimate documentation stating that the BEGI unit does not perform? (no im not talking about their customer service, ive read that thread )

 

Right now I don't know of any place you can buy good CNC head flanges from. I was talking to a shop to get some made last fall. I needed to order a minimum of 15 to get them made and only have 4 or 5 people interested in them. I don't have the capital to sit on 10+ flanges and just hold until I possibly sell them sometime in the future.

Besides dealing with Begi, I honestly think they are the only ones actively making intake manifolds if you asked.

 

Completely understandable with you not wanting to just sit on flanges with hopes of them selling, I wouldnt have done that either.

And in regards to BEGI manifolds, it seems like people dont really want anything to do with their manifolds, is that primarily for performance reasons with them, or just their overall shitty customer service? Personally I can deal with shitty customer service to a solid performing product lol

Here is this thread as well- https://www.miataturbo.net/bellengin...anifold-27089/

 

I have a local source for laser cut flanges (no machining) if there is any interest. I've also got the S2 from Sav's old car that I'm not planning on using.

 

For an N/A build with less than full race cams, I'd suggest using a 4G63 IM as your donor. Much closer to what the BP wants than any B series Honda manifold.

 

When I moved from stock NA8 intake to the skunk2 I picked up gains across the rev range. As Emilio points out earlier though my engine is not even close to what you'd consider streetable. The stock intake in my case was limiting airflow massively. This is not the case with stock engines.

Still I'm interested because I'd really like to see the results of a stock engine on a dyno especially given runner length is only one factor to intakes. We know the square top helps but is it due to increased runner size / better internal flow path / better harmonics? It will be a combination of all of them. The Skunk2 might not have ideal runner length for a stock engine but the gains elsewhere could make it worthwhile.

Thats the problem with air intakes. Sometimes strange combinations work better than you'd expect ... and you won't really know until you try it.

 

Anyone wanting CAD profiles here is my online file share of ones people might find useful. Please note: use of my designs is for non commercial use only. Please test fittment and dimensions prior to making.

MadJak's 3D and CAD files

If anyone wants it I can CAD a later model intake flange. Someone will need to proof fitment though. In terms of getting them made, I use a local waterjet place and they'll cut a single 10mm flange for $50 US. Cnc tends to cost a little more on the thicker cuts.

If you plan to fit a Honda intake you need to undersize the port holes on the flange then port them once welded to match the angles in the head and to the runners on the plenum. I think I have a CAD profile online thats had the two external ports narrowed for this purpose. Have a look at my thread reharding welding braces on to stop the cracking. Mine is holding up well.

 

Just to clarify, are you suggesting the stock intake manifold or an aftermarket ones?

 

OEM. There are a few variants. I've drifted this thread a bit though (sorry!). Start a new thread if you want to continue your research on non-Honda options.