So I recently came across a BEGi manifold(not the cast one) for kinda cheap. It has a bbk 70mm tb. I’ve searched through the forums and I’ve heard some good things but mostly bad things about them. What are the main benefits of that intake manifold?

Before I was contemplating on fully gutting and porting the vtcs manifold or just getting the skunk2.
Which intake manifold should I use?
How much should I sell the Begi for if I don’t use it?

 

Of those options, Skunk2 is the better option. Even a gutted VTCS manifold is restrictive. Assuming the BEGI is a fabricated type based on your description, there is always concern of fatigue failure at the welded joints. From the images I can find, it has short runners which don't work great on stock to stock-ish BP ports.

 

That entirely depends on the context of what your car is like now and where you wanna take it.

I don't find much value in chasing detail improvements to airflow on a boosted car when you can just crank up the boost. Gut the VTCS butterflies, keep the manifold brace, and enjoy the proven, low cost nature of OEM parts you already have.

I also don't have a boosted car.

 

I like my skunk2 a lot, easy mode -- wife got it for me for christmas, so can't beat that. Is it significantly better than the other options? Meh, debatable --- is better than the stock 94 one I replaced? You bet

 

Yea im leaning towards the skunk2 now. It lookes so much better in my opinion. If someone wants the begi manifold Ill sell it for 250$ or ill just keep it as a cool/rare car part paperweight lol

 

Any reason you're not considering the squaretop? This is the way I went as it was cheap and oem. I haven't seen the skunk2 in person but I'd guess the big advantage is that the skunk2 is lighter and may not need a brace..?

 

Yea no need for the brace and looks a bit cooler I guess lol. And its easier to get to the injectors.

 

Why are any of you all even running that brace at all? That's the first thing I remove when I get a new Miata. I've had turbo miata's since the early 2000s and always removed that brace, makes doing oil changes a lot easier and I've never had a failure from removing it. Also, I recommend the square top I run one its been great

 

As an engineer that's dealt with continuous cost cutting, I am disenclined to believe that over 4 distinct iterations of the B series engine they left extra weight and cost on the table without studying the pros and cons of removing it.

Also, a very few higher mileage track cars have had issues with intake manifold cracks, and I would expect removing it doesn't help with the more common throttle body cracks. Increase the risk of that for what, 1.5 lbs and easier oil changes? No thank you.

 

Lol that's exactly what my engineer buddy said, guess what I still remove them and in 20+ years I have no issues. So my real world evidence disagrees

Also, interesting I had the very first begi intake manifold ever made for a B series Miata way back in the day. Iirc it fit horribly and left a lot to be desired. That was the first iteration of that manifold

 

Braceless heathen here, no issues so far on my car. That said I can't argue with the engineers perspective. I honestly can't remember if my flat top came with one or what I did with it, or else I might consider adding it back.

 

I've had one of my manifold bolts on the end shear off with the brace off. Maybe it was old or overtightened but I did use a torque wrench when tightening. I replaced it a while back and no issues yet.
On a second note I have a bp4w head off a msm and a vvt head. Which one should I use?

 

No brace. 325whp track car.

I think the brace was because they were having problems with the throttle body failures. Put a skunk2 on it and never look back.

 

Good deal, yea literally all of my buddies who own miata's (quite a few Miata buddies I've accumulated over the years) remove said brace and never look back. I'm sure there was a sound engineering reason behind it. However, I also know a lot of engineers and they like to think they are always right no matter what.....why? They are engineers and went to school for it and so now they are emboldened to think they cannot be wrong and every decision they make is correct lol. God love em

 

I personally run the brace, even though my car is probably not at risk. Only takes about a minute and a half to remove and replace. There are definitely instances of high power track cars with removed braces and damaged intake manifolds.

 

No access issues with oil/filter changes with a smaller intake brace - either angle grinded OEM or aftermarket versions.

 

10+ years ago I would've said just remove it and it'll be fine. These days I'm of the opinion it was put there for a reason and err on the side of caution. Will everybody experience problems? No, but ultimately it's your call. I'd say it also depends on your setup. If I was running a skunk2 IM I would worry much less about the IM brace (as the IM is lighter), but the OEM manifolds are fairly big/heavy so if you can run an IM brace it's probably a good idea. Ultimately the car isn't going to burst into flames so not a huge risk we're talking here.

 

I'm with OptionXIII, it's there for a reason. Some have theorized it could help reduce vibrations at the throttle body (which break throttle shafts) by acting a damper. It also doesn't weight that much. If oil filter access is a problem (especially with an oil cooler sandwich plate), just notch it to clear. It's only 3 bolts to remove if I do need to get behind it. Rather not chance a failure at the track over something trivial to deal with.

 

+1 for skunk2 mani. Running it alongside the skunk2 TB. It's been proven that the skunk2 has a slight gain over the square top in FI, and an even bigger gain over the others. If you do get a matching skunk2 TB, just make sure the adjustment screw is set properly lol. I've read that they've come undone on people, including myself.

Toss the brace, my lifted Miata that I offroad violently doesn't have one. The only thing I broke on it so far was a control arm, multiple shocks, passenger airbag, and my back. Brace is pointless imo. weight reduction bro.

 

I bought the skunk2 lol