Did some experimenting last night at the 1320 dyno. Played with timing and shift points.

From 17 degrees to 25 degrees, the car's ET and trap speed didn't vary any more than what could be expected from different launches. ETs stayed within two tenths, MPH stayed within one MPH. Interestingly, on 25 degrees the car posted its lowest MPH, but ETs were among the best. I also played with shift points, and at all timing settings, I can shift anywhere from 6800 to 8000rpm and it doesn't make one bit of difference in ET or MPH.

I let the car cool off a bit while timing was still at 17 degrees and completely flubbed the 2-3 shift. Went round-robin straight back to the track (light day, no waiting in the staging lanes!) and blitzed off a pass 2-3 tenths quicker than any other, and one MPH higher! Quickly bumped timing to 22 and lost the power again, but not sure if this was due to heat soaking.

I'm a little intrigued that my car is *that* insensitive to timing, yet still pretty bummed that I can't find any speed! This engine is ridiculously slow for the amount of noise it makes and fuel it consumes. It's almost embarrassing. Makes me want to just go back to a street port and build the thing to handle 10-11k.

 

Whats the ET, MPH, and the weight? I have always used the "advance timing 2 degrees till MPH starts to drop off then go back 2 degrees". But if you are not showing any improvement something else may be wrong. What split were you running?

 

Zero split. Can't run split.

The recycling yard said my car weighs 2360, but they also said my other car weighs 2950 when every road test from the era had it at 200lb more, so I don't trust their scale. It weighed 2450 on a more trustworthy scale before I put the FC subframe and ~60lb skidplate on the car and added a whole lot of metal to the rear suspension. So, there you have that.

Times, again, are downright pathetic. Very high 14s and MPH hovering around 90mph. 6 ports just plain suck!

 

That should be in the 140-150 hp range. What all have you done to the engine?

 

yep

 

is this one half-bridged?

 

Are you using s5 or s4 intake manifolds?

 

Yah, half bridge. It feels a lot better than when it was a "third bridge" but I think having the eyebrow connect the two ports was a bad idea.

Same S4 N/A intake manifold and throttle body and exhaust system that did ~215hp on my mild half-bridge T2 engine, different lower obviously.

 

Throw the six port in the nearest lake and build a nice 4 port full bridge motor and be done with it.

 

I'm just waiting for my 6pt sp s5 to die, it just wont!
I'm only missing the essential gaskets and a center iron to build my 4 pt, unless it turns into a PP...

 

But I don't want a full bridge. It's starting to get tiresome. I want a car that I can drive all the time. Can you believe that I've had this engine running for over a month and I've only put two thousand miles on it? That's because of the 18mpg.

I'm thinking, just use these street ported S5 T2 housings I've got, the ports are actually WAY TOO BIG but I am curious to see what the S4 N/A manifold does for a street port since I only ever tried it on bridge ports, and that big street port 6-port I did that died an early death.

Then again, I might also build a T2 engine and use the T2 manifold, with some extra attention paid to the water passage area.

And I somehow have a WEALTH of FC rotor housings in decent shape. I must be the only guy who buys core engines and the rotor housings are the only decent parts left inside. Kinda like Charlie Brown getting a cereal box full of prizes and only one piece of cereal. So I have also been thinking, hell, I made one peripheral port, why not another? It's been a long enough time ago that I've almost forgotten how much of a pain that was. Plus, the GpB RX-7s were peripheral port...

And, hell, if I do a street port and get tired of it, I can rebuild this dog with 12A plates and carbon seals and I have a way of putting one of my modified 12A manifolds on a 13B. Duplicate the Group A bridge ports and use a hulled-out, modified Nikki as a throttle body. But that will be after I forget how much of a PITA it is to drive a car that requires a loud exhaust to even run.

Hmm, I just had a thought... I wonder if it is possible for a glasspack to collapse internally like the old dual-wall exhaust systems used to. It's worth investigating, anyway, and my exhaust is mostly slip-fits so it's easy enough to check.

 

when we were putting the glass packs on my car, chucky told me on his friends car, he hit the gas, and the packing just came out, so i bet they could collapse....

i'd probably build the 4 port street port, and then go P port....

 

Renesis is going to be too much trouble, but if you wanted to do a 6 port street car why didn't you go with street port + properly functioning s5 intake manifolds? The s5 intake manifolds are far better than the s4 due to the variable length runners and more reliable aux port actuation.



Gray is the VE curve for the 4 port Renesis (early model year USDM automatic model engines). Black is the 6 port manual transmission engine. Purple hashed line is the VE curve on a stock s5 engine. Here is a graph of the s5 runner lengths:



The fixed-length s4 runners create the "B" torque curve. The s5 system uses the VDI actuator to switch between the "D" and the "A" runner lengths to broaden the usable torque.

 

The only - ONLY - reason I bother with six-port engines is because that is all I can really get. I have a LOT of six-port end housings. I have only one useable T2 center and one T2 rear and both are too heavily street ported to do much of anything with besides run them as-is. I have a line on another rear housing, but I'd have to bridge port it to match the only non-massively-ported front housing I have.

I don't run the port sleeves because I think it's a lousy design, forcing the airflow to move past the actuator rod. Besides, I've never received a 6-port manifold that didn't have seized or broken actuators, and at least one shaft will be screwed up too.

I'm not sure I could even use a S5 manifold. I might be able to rig something up using God-knows-what to actuate it, an RPM switch to control it, and dual table code in Megasquirt to change the fueling based on a switch on the VDI mechanism, but that doesn't even get around the fact that I don't have ant S5 intake manifolds or feel like spending $100-150 for one from eBay that probably has broken actuators anyway... and we're talking about a lot of fab work, too. Probably most of the fab work could be negated by just running MAF code, but I haven't heard good things about it yet.

I don't trust actuators to not fail or stick or otherwise not work as intended.

 

If the engine is regularly pre-mixed, they should never get stuck with the oil film that works it's way up the runners. I rebuilt my S5 vert back in 2005. That engine now has 45k on it. 99% of those miles are granny driven miles and 3k rpm shifts. Any average 6 port engine treated like this will have excessive carbon build-up and stuck aux sleeves. Not mine! I haven't driven this car in 2 yrs and I can go out and still rotate my aux actuators easily by hand to this day.

 

I hear you on the actuators thing, they do tend to be a pain in the ***. But I agree that premix will help keep the carbon down. Using the OEM airpump and solenoid (the stock design for s5) is going to be the most reliable way to operate them. Worst case scenario is that you could remove the 6 port sleeves and just use the VDI to change the runner lengths.

Renesis really would be ideal. But its mounts and control systems are different enough from the older rotaries that swapping it in is not a straightforward thing considering it was designed for a returnless fuel system, electronic throttle, electronic aux port sleeves, and vacuum operated secondary ports and intake tube.

 

You guys aren't listening... the ACTUATORS are usually siezed. The bit on the outside that converts exhaust system pressure into linear motion.

And don't make me laugh with regards to carboning... I exclusively premix, and I usually pour oil out of the secondary runners when I pull an intake manifold...

 

why dont you just semi-p-port a small street 4 port motor?

 

So, I replaced the sensor for my LC-1 (untold gallons of coolant, many Block Welds, lots of oil, and three of the wires had the insulation chafed off partway up) and found that what I thought was 12:1 was really a lot richer.

So it's merely slow now instead of pathetically slow Leaned it out a LOT and found a good deal more power, now we're mid 14s at mid-93s. And it keeps making power right on up to 8000rpm. I may get a 8000-8800 set and put an 8400 pill in the rev limiter.

Bonus: I cut a .0006 light on one of my runs.

 

Put a standard HT18S-2S on there and you will be talking about 112 - 115 MPH.

Combine that with a stock port and gearing for 115mph in 4th @ 7400rpm and it will be blisteringly quick.

 

Turbos suck. I break enough transmissions with N/A torque. I overheat enough with N/A heat. Unless you think a turbo engine will be fine with a 60 second long dyno pull with no airflow, no engine acceleration, that starts at ~210f coolant temps... I know I can barely keep N/A engines alive doing this!

Since somebody helped themselves to all of my spare transmissions and all of my good rotor housings and various other parts, I'm probably going to be going 3400/4L60 this winter. Not entirely sure what I'm going to do for a rearend, yet.

 

dont do it, just side draft it and street port it, reliable and cheap! all the fun!

 

With what parts? Parts all stolen.

I can either re-accumulate parts, or do a piston engine swap and eliminate 90% of my problems, or I can crush the RX-7 and built an AWD Fox like I've been wanting to do.

 

Fox it.

 

Would you believe that I just turned down a complete 323GTX (some assembly required) with a freshly rebuilt transmission, fresh bottom end, fresh head, etc... for less than a set of rally tires would cost? NOT ONE OF BOB MARTIN'S.

I am either a realist or a complete moron.