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cant wait to get a closer look at the usefullness of a nb6 intake vs usdm.. maybee some dyno numbers. volume numbers? I always felt the 1.6 intake did not have enough plenum for 7K RPM
Same rules here. One move is pretty much the norm across the globe. That driver, on his provisional (learners permit) license no less, had the audacity to tell Sonny (pro coach, 3x national champ, multi lap record holder) "That's what racing is, get used to it" or some such malarkey.
Said driver has been contacted nad "talked to" by racing organization after chief steward saw the video. I believe the race directors comment to Sonny after viewing the video was.. well, lets just say the RD might not have been so patient had he been in Sonny's seat.
On his provisional and he did that?!?!? Fail his ******* *** and send him back to DE3.
We measured the lobes and checked the casting marks on the camshaft today.
NB6 intake (B6KP): 7.25 mm
NB6 exhaust (B6MC): 8.25 mm
For reference,
USDM NA6 intake: 7.86 mm
USDM NA6 exhaust: 7.9 mm
Checked the timing belt for misalignment, but the timing looks good.
USDM NA6 manifold and auto trans TB showed up last week and visually compared it to the NB6 manifold. Looks like the TB on the NA6 manifold mounts further back than the NB6. Also noted is the downward angle the NA6 manifold has compared to the more parallel to the ground angle shown with the NB6.
I believe that is so that the NB6 can share the NB8 intake crossover pipe that runs above the upper coolant hose, opposed to the NA6 which runs beneath the water line.
Can you confirm if the TB mounting pattern for the NB6 manifold is the same as the 1.8? Being able to add a Junk2 TB to an NA6 might be nice.
Yup. Those of you 1.6 guys wanting a Junk2 throttle body, get you an NB6 intake manifold. Also gets rid of what i-don't-even-know-what-the-hell-that-crap-is IAC system.
Yup. Those of you 1.6 guys wanting a Junk2 throttle body, get you an NB6 intake manifold. Also gets rid of what i-don't-even-know-what-the-hell-that-crap-is IAC system.
You mean the delightfully-inconsistent thermostatic jam? I love my 1500rpm-warm-idle-but-nah-jk-550rpm-sike-now-back-to-1400rpm-idle tho!
So far at least, it appears starting with a freshly rebuilt NA6 motor is probably a better choice. While you are rebuilding, shave block to bring CR to about 10.0:1 while retaining squish. If you have budget leftover, deshroud and bowl blend. That should, base don our past experience, get you to about 135whp on corn.
Meanwhile, we'll swap cams and start A/B testing intake manifolds. Also ordered a JR header (4:2:1) to A/B against the RB (4:1). For science.
Pretty accurate assessment. Here is a fresh NA6, .050 off the head, stock valves, stock 1993 cams, super singles, RB header, 45* intake tube, haltech, E85.
And for a little future reference if it may help someone, same motor with port matched T3 manifold and black top 4age ITB'S , 100mm trumpets with ITG filter installed.
No gains were found with cam timing adjustments as well on either setup.
Pretty accurate assessment. Here is a fresh NA6, .050 off the head, stock valves, stock 1993 cams, super singles, RB header, 45* intake tube, haltech, E85.
And for a little future reference if it may help someone, same motor with port matched T3 manifold and black top 4age ITB'S , 100mm trumpets with ITG filter installed.
No gains were found with cam timing adjustments as well on either setup.
Interesting, so any idea what comp ratio is yielded with a 50thou head skim?
Emilio; any reason you specify shaving block vs head? Don't the stock pistons protrude ~.010" at TDC with a stock deck height?
Whatever method preserves squish. I'm not too familiar with the B6. With BP's, it's easier to deck it. Less machine work to preserve squish and deshroud areas that way.
In either case, stick below 10.3:1 or so for CA91, 10.4:1 for 93. If only E85, then 11.0:1 works nicely. B6 makes a good enduro motor as it's pretty easy to get it to run the 2hr max driver stint length for most sanctioning bodies. But it'll only do that on gas, thus the conservative CR for enduro.
We have not pulled the head and hope not to need to.
Adapting NB Throttle Body to NA6 USDM Intake Manifold
In the quest for more power, we are going to try using a NA6 USDM intake manifold. To avoid unnecessary splicing of wires on Miller's engine harness, we are going to adapt the NB throttle body to the NA6 intake manifold. Here some mock up and progress photos.
Top two holes of the TB and IM line up perfectly, but some air channels on the NB throttle body look like they will cause vacuum leaks.
The bottom two holes do not line up with each other.
Not only bore hole sizes are different between the NB TB and the NA6 IM, the centers are offset from each other.
John getting to work on porting.
Beautiful smoothness.
There's a problem trying to seal up potential vacuum leaks, but another gasket can fix this.
There's the second gasket mounted backwards on top of the first one.
Note that we had to slot one of the holes for the NB TB to mate to the NA6 IM. A nut and bolt will work here to clamp everything down.
Modified NA6 manifold ready for install. We are crossing fingers that it may make more power.
It seems the JDM B6 has two water ports that connect with the intake manifold.
Though the gasket has holes for both water ports, both USDM NA6 and JDM NB6 intake manifolds have the trapezoidal water port blocked. Both manifolds have the circular water port to allow coolant to flow to both the NA6 and NB throttle bodies.
Backsides of the JDM NB6 (left) and the USDM NA6 (right) intake manifolds. It is interesting that the runners on the NB6 IM is more squared off than the smoother, wider radius of the NA6 IM's runners. Maybe the smoother, wider radius means more air flow and more power? We will find out on the dyno soon.
Side views of both JDM NB6 (left) and USDM NA6 (right) IMs with NB throttle bodies mocked up. Note the longer and straighter approach to the plenum from the TB for the USDM NA6 IM.
Close up of the USDM NA6 IM.
Close up of the JDM NB6 IM.
Handmade idle air control block off plate for the USDM NA6 manifold.
59 mm inner diameter for the TB opening of the JDM NB6 IM.
55.5 mm inner diameter for the TB opening of the USDM NA6 IM.
Verified: NA6 and NB6 IM gaskets are the same.
USDM NA6 dressed and ready for install. 1.6L fuel rails are interchangeable between manifolds. Also, 3 vacuum line bungs had to be capped.
Swapping TB cables because of the different TB bracket mounting locations between the NA6 and NB6 IMs.
Mazda marketing literature from NB6 era states that it was tuned for more torque. The B6 was already an archaic design in 2001. Tough to meet emission standards. No real reason to tune it for power when anyone that could afford power would just by the BP version.
Of note were the advertised peak power rpm of the 90bhp NB6 at 6200rpm, same we saw with ours in stock form. Swapped cams and still 6200rpm peak power. That is all intake manifold influence I think. For reference, a stock NA6 makes peak power closer to 7000rpm. The two key items of the NB6 responsible for it's meager output were cams and intake manifold. Changed both, Dyno this afternoon. We'll see.
No joy. Made a few more whp with the NA6 IM and RB header but still way below what we need to be competitive in ST6. Motor, at 6% leakdown is just too tired.
Of note is how much less the RB fell off after the power peak.
JR vs RB header. In the past, with much bigger cams we saw the 4:2:1 JR worked better than the RB. As the cams get milder, the RB seems to have more total area.
NA6 intake manifold vs NB6. We expected to see the power peak more than the 150rpm we see here. Also expected another 8-10whp, not 2whp .
I made a lot of pulls doing sweeps on injection timing, ignition timing and AFR on each hardware combo. So each was optimized.
Based on the 125whp we made with a Mazda NA6 crate engine, E85 and RB header, I think we would hit 135whp or so with the Kelford 203B cams.
Sonny will decide if he wants to put a BP back in or not.
03-28-2019, 09:47 AM
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