I can't wait to see the reply! Hahaha, you've got me checking the forum in my free time.

Also, what gearbox would you (or anyone else reading this) run behind a 1/2 bridge 4 port 13B? I'm thinking Turbo II but i know the ratios would probably not be "the best" for the powerband. Would a rebuilt S5 N/A box hold up fine with the amount of power?

 

I have been gathering pats for quite a while to do something similar, but since my budget is small I scour the scrapyards. I picked up a pair of throttle bodies for some N/A 300zx(z32), Gloria's, and the 6cyl maxima. These are twin 40mm setups, and having two of them gives me 2 sets of 2 throttle butterflies, each pair is linked and has a TPS. My plan is a semi PP with the primaries one one set, and a small PP on the other. If you really want to be fun, get three sets of two and run primaries, secondaries and a PP. with a hellacious amount of manifold fab, they could be staged progressively.

Isaac

 

My bad. At one point I thought he was looking at the Tweak-It TBs.


Have patience, it may not be done til Sunday eve or Monday. A TII tranny wouldn't hurt but the gear ratios and high rpm powerband for 1/2 bridge may not be the most desirable combo. Which ever you choose, have it rebuilt


The Z32 throttle bodies sound interesting. I have an extra '87 Z31 but it's a single TB. Post some pics of the Z32s. Never have seen them. If you can set them up progressively you might be able to use the single Z31 TB for the primaries. The NA FCs have a large single butterfly for the primaries and a pair of smaller ones for the secondaries/auxiliary ports.

If I read this correctly, you're looking at running one pair of 40 mm TBs for the primaries, a second pair for the peri-port and not even using the secondary or aux ports? Now that could be very very interesting. Time to all Howard and have him get out the timing wheel.

 

Yes, as long as the roads aren't salted.

Honestly, the only difficulty is cruising below about 30mph or accelerating gently from a stop. The main drivability issues i have are related to not having the warmup cycle properly tuned (this is the most time consuming thing to get right, and my laptop died before I could do it) and not having any kind of idle control. Basically, problems that happen on any engine.

 

i'd skip it and go full PP. mine is carbed, and its still in the tuning phase, but drivability is surprisingly good. i can putt around @10mph if i want to. its like PJ's car, but the PP doesn't seem as bad

i don't see what the semi PP would gain you, the full PP has more power @1000rpms than the stock 12A does....

the downside is NOISE, it comes from everywhere, particularly the intake

 

A thought - what kind of flywheel do you have? I'm running this SR aluminum unit and maybe it's light enough that at city cruise it doesn't damp out the engine's natural bucking as much as an iron one will, when the engine is at basically zero load.

 

I don't know of anyone who uses Tweak It gear over here.

But ALOT of guys over here use EFI Hardware stuff.

LINK: http://www.efihardware.com/products/...ttle-Body-Kits

I converted my daily to a bridgeport, efi 50mm ida throttle body with 550cc injectors, microtech m4 fuel only computer....unfortunately I only drove it for about 20 miles before selling the car and going efi turbo! :O(

It was very smooth power delivery from what I remember.

 

A full PP has crossed my mind several times, but even putting around at 10mph, a full PP is using a ton of fuel (from what I have read/heard). With a progressive setup low load/low rpm would be fed through slightly massaged stock ports. While this would make less HP at low load/low rpm than a full PP it would also be capable of stock-like MPG, sort of a have your cake and eat it too .

 

Why don't you guys just build a proper 6-Port - with Bridged Secondaries?

You'll have good idle, good mileage, more torque than any PP, and still have plenty of power in the upper RPMs.

Not to mention...super availability of parts.

 

i think you're right, i heavier flywheel would help. i have an RB aluminum one.

the PP will buck and snort, if its rich. it also helped a LOT to reduce intake manifold vacuum. two .025" holes made a HUGE difference in drivability

 

i don't know about the mileage yet. no license plates (its a race car), so i haven't gone far with it.

my next trip is the grocery store, its 3 blocks, but much internet bragging rights

 

please elaborate more, u added these holes where?

 

throttle plates. part of an experiment to try and get the engine to idle on the carb's idle circuit.

that part didn't really work. and the holes only work in a range of sizes, too small, didn't do anything and too big and it didn't run anymore. currently its at .025" and i might go slightly larger, but i wanna work on the mains...

 

Bump to see if Trochoid is ready to spill those proverbial beans.

 

I missed this...

Um.



Nice "high RPM powerband" there. More torque at 3200 than the same engine before the bridge did at peak.

This, BTW, was with total timing at only 18 degrees. And ignition breakup issues, thanks to some crappy plugs I was using.

Sadly, I have to go back to 6-port now, the rear end housing is FUBAR and I have no more TII stuff.

The trick to drivability, I found, is make it idle on the secondaries as much as possible. That way, there's minimal vacuum at the bridge, so it pulls less exhaust gases up. You still want to get your main driving airflow through the primary throttle, but minimizing vacuum at the secondaries is key to getting good drivability.

You do lose the brap, though.

I didn't realize how quiet my exhaust is until I shut the car off on the highway in gear and went WOT (trying to clear oil out of the intake manifold - long story) and the intake noise was almost as loud as when cruising at 65mph. That also does say something for how loud the intake is... and I'm not running a Weber or Holley style intake/throttle setup, just stock S4 N/A with a cone filter stuck out near the radiator.

 

I've been doing lots of reading up on motors lately. I'm over due for a rebuild and want more n/a power.
I am looking in s5 rotors in REW with S4 front plate, Bridge secondary on s4 w/ s5 rotors, or a TII long block this S5 rotors.
I haven't found much info or feed back from people who did similar. Defined auto works said if I source the REW and front plate that it would cost around $2500 for the build with a street port. Said it has a broad torque curve.

 

Bump for Trochoid and my fellow knowledge seeker right above me.

 

nobody had anymore t2 stuff, and the stuff they do have is all used and worse than yours! mazda has new parts but, you know.....

i found much the same with the P port, less intake vacuum = less brap = better manners.

 

Any news, brother man?