• Very similar to my build up... Except I'll be running a forged bottom end and a snail-lookin thing in the intake tract.

 

So in other words, totally different from my build

 

More info please? What TB will it accept? Mustang?

 

Just a concept at this point. First thing is to see how high we can raise the roof of the intake port and what that does to flow. Joe is pretty sure that's what will wake the BP4W/BP6D head up. Once that's optimized we mock up a matching intake manifold and test it on the bench. If the combo does what we want, I make a CAD drawing for the manifold. That drawing goes to a friend for some CFD analysis. Once we have a shape we print (rapid prototype) a sample. Verify flow results on the prototype head. Then we make a tool for an injection molded ABS intake manifold and digitize the head for CNC porting. Put a beta motor together, run it on the dyno.

Voila, 200 easy steps!

Part of the concept is to make the manifold compatible with most of the stock hardware. So in theory, you would be able to fit your IAC and most everything except EGR. I think making it deal with the heat of an EGR pipe would require an aluminum insert and heat sink. More trouble/cost than it's worth. But otherwise you could maybe bolt one up to a DD with the CNC head and have it all look sorta stock.

If it all works as I envision it and the manifold is a success, we would proceed with a BP05 (90-97) version. VVT heads are becoming cheap and common because no one knows how to deal with the cam timing yet. But that intake cam is a gem, fairly steep ramps, .371 lift and the head is otherwise a 99-00. The 99-00 BP4W heads are becoming rather precious though. I'm starting to see BP4W fetching $650 on ebay when a complete VVT will go for $400 and a complete BP05 for maybe $250.

Of course if Joe figures a way to get a Honda B18 head on the B series Mazda block, all bets are off

 

Custom intake manifold, prototype head... What kind of budget build up?

 

Sounds good, looking forward to results. I would consider making an option for a larger TB available. I think there are significant gains to be had on a N/A motor with a larger TB like one of the BBK models for mustangs. I know a lot of guys are over-boring their stockers right now, but there are complications with that leading up to possible ingestion of TB parts leading to catastrophic failure.

 

This car will eventually get all manner of prototype parts tested on it but they are not part of the car's budget. It's motor is built already and cost me around $2000 in all.

 

I've said this like 10 times at miata.net, and every time I was either scoffed at or ignored. A PCPRO type device that specifically dealt with intake cam timing would not be tough to develop, market, or produce. What people don't seem to understand when I bring the topic up, is they think I want to use 99+ style engine management with the intake cam-located cam sensor, and anyone doing this type of swap has no desire to use oem engine management. They'd use at minimum a CAS bolted to the back of the head, or a multi toothed wheel at the crank.

 

Yup. On my to do list is a standalone programmable PID controller for the VVT. With that suddenly those heads become much more valuable than the BP4W's. Imagine a .450 intake cam with MMD lifters that you could swing between say 10° and 50° overlap based on a user defined 3D map. Solid idle and big power. You could quite easily get a monster intake cam to pass a sniffer.

 

Nice. If mine doesn't sell quickly, I'll hang on to it in anticipation.

 

And I'll hang on to both of mine. I already have the stock intake cam sensor as well as a CAS on the back of the exh cam from when I was running the Tec3 sequentially. But still, you dont need a third sensor. crank and intake cam is plenty.

 

cool ****, son.

 

.

 

I think only the NB Hollow bar has two mounting holes for the endlink. NB bar also has a thicker wall thickness.

 

hollow bars.......OD"........ID"............OD mm........ID mm
nb big............1.25.....0.18750........31.75...... ....4.762 5
nb small.........1.125....0.18750........28.575...... ..4.762 5
na................1.125.....0.12500.........28.575 .........3.175

if anyone cares

 

Can we stay on topic?

 

As the man said.

When would the 15x8 be faster then the 15x9?

I remember you posting over on m.net that you developed the 9's because most if not all of the 225/45 or 50 R's were showing signs that they needed a bigger wheel. Isn't more grip quicker then a lower rotating mass for 99% of the courses?

 

Even with the lowest power, if there are no straights, 15x9's with a slightly bigger tire will be faster. On fast tracks, the 9's probably won't be appreciably faster on a low power car. Start getting above 130whp and the 9's will be faster pretty much everywhere you can possibly run.

As a data point, Spec Miatas running a 205/50 on a 7" wheel usually run about 40psi hot. The same tire on my '91 that's close to Spec Miata speed and weight but running an 8" 6UL only needs about 31psi hot to get the most from the tire. I get more steering response from the same tire because the sidewall is in higher tension fromn the wider wheel. The greater air volume allows lower air pressure which helps the tire conform to the track surface to improve mechanical grip. The lower pressure also lowers the tires spring rate which makes the tires easier to drive and suspension set up easier to do. Just stack of win-wins for about a 1.3lb weight penalty.

Racing classes sometimes limit tire size, but always limit wheel width.

 

i think your on the right track for keeping the front bar on the small side. i put the 1.25 RB NB hollow bar on my car with 600/425 rates and you could feel the big bar hampering the car. in the rain it was almost no fun to drive.

the R1's are nice tires your car should grip like crazy

 

is there a difference between shaving the head and getting higher comp. pistons to raise compression? also are you gonna be looking into replacement body parts to save weight or just strip and gut?