Agreed. P.s. I fixed your bastardized hunk of diarrhea. and wired it to work.
I'm doing a skunk II to replace it right now.

 

I've been following this thread with great interest.

Two questions--my assumption is that a turbo intake and a NA intake would be different. Generally speaking, longer and smaller I.D. intake runners for NA, and a larger (150%) plenum for a turbo setup.

As for a 68-70mm throttle, Skunk2 just came out with something close. This makes sense to free up a potential bottleneck, although the throttle might become a "light switch" or bog down WOT if too big.

Right?

 

Sorry if already mentioned, but Skunk2 just released a 64mm TB for the Miata to address the "broken TB screw getting sucked into your intake at high RPM problem". See Good-win:
Miata Performance Parts : Miata 64mm Pro Series Throttle Body : 1999-2005

 

I think going with a Honda throttle body in the first place with the honda intake makes more sense. That's my opinion but most of these manifolds can be bored to 70mm for a 70mm throttlebody.

 

Skunkworks makes a 70mm TB for the Honda manifolds, too. Up to 74mm, IIRC.

 

Yup thats my point. Not to mention many more companies. The price is better and the variety is better with the honda flange, and making the miata tb fit the honda flange is kinda more of a pita than making 3 wires go together.

 

Exactly.

 

I dont think most of you need 70+mm throttles. I cant tell you how many Hondas Ive seen running 72mm throttles because they think its cool, and the cars drive like ----, are hard to tune, and make less power than they would wityh a smaller throttle. Im not talking about stock bottom end turbo setups, Im talking about built B-series with big turbos.

The OEM 62mm Honda TBs are not a restriction until around 400hp and the 68mm is not a restriction for almost anybody.

 

And if you want to figure out what size TB is even realistic. http://dairally.net/daihard/chas/Mis...aiThrottle.htm

 

Very cool tool leafy. I got 62, 66, 70 based on all my engine specs on a motor making ~300whp. The capacity index method gave me a 70. Interesting. Wonder if I could make more power with a bigger tb or if it would just kill me everywhere down low.

 

have you seen the dynos of the GT2560 with the BEGi IM and 70mm Mustang TB? gains everywhere, including low-end spool.

 

I got the 68mm Godspeed TB along with the godspeed intake mani.... the inlet diameter on the IM is identical to the Godspeed ID...pretty good combo IMO and cheap. We'll see how it holds up lol.

 

What was your near equal velocity number? The first size it give back. Its really hard to loose low end power by going big with the tb until it becomes way bigger than the intake piping. But you start to loose throttle control where you basically start making the same power as wide open throttle with the throttle not open all the way.

 

It was like 84 even. I will be looking at a 70mm unit in the future. CNT, Skunk, and Godspeed all look like good values. I see skunks used from time to time.

 

Well I'm getting mine Dynoed tomorrow. I hope to be able to see gains everywhere.

 

Both TB's same day/dyno?

 

I wouldnt worry about 70 then. The capacity index one seems the best in general, but I've only really played with it n/a. But I like this calculator because it gives you the results from all different models, and they all certainly have merit in one way or another. for the most part, until you get to about 15% larger than the intake tubing leading into the tb you're only going to see positives, with just a tad loss of throttle modulation. This does assume that the tube leading to the tb is properly sized for your application. After that you loose more and more modulation and then start to lose in the low end. You can theoretically make gains on the low end using a very small tb but it requires you to taper into and out of the TB correctly, and kills the top end. But there's ton of tb theory out there, its pretty silly.

I've made tb's before but only barrel style, they're great for 30mm tb but once you start getting over like 45mm ish the external dimensions skyrocket. I was designing a 75mm one and once it got to be like 5" x 6" x 4" for external dimensions I stoped, and at that point it still wasnt going to seal very well for idle. but a 30mm can easily be made from a 2.5" cube.

 

That would be really interesting to see.

 

I've got a new 70mm unit waiting to be Franken-tested. That and a custom IM are on my list of to-do's.

 

Whats that off of? It looks opposite of mine with the TPS and throttle cable flip flopped compared to the rest of the unit. Could be upside down :-) but it looks like the IAC mounts on the bottom as it should just as it sits.

probably B18 etc though?