I've delt with that before with larger turbo intakes (4"+) collapsing in boost with some air filter restriction. Unfortunately my usual fix is to make the intake out of aluminum....which would sort of defeat the soft mounted throttle body. But you could probably use 2 short straight couplers with an aluminum elbow welded to your throttle body adapter.

 

Yes, this is the direction I'm thinking. Overthinking, of course. Amongst other thoughts, the one that just popped into my head that I would like some feedback on from the hive-mind is:

• What are your thoughts on the increase in throttled volume due to moving the throttle body even further away from the intake manifold?
  • If I go this route, should I (or do I need to) have it retuned to keep it from going kaboom?

Right now, I'm thinking that I'll:

• Fix my damn lathe
• Order the $40 aluminum 60 degree elbow from Summit
• Chuck up the beautiful Winning Formula piece and cut off the flange from the manifold adapter.
• Counterbore the adapter just a smidge to a close fit on the aluminum elbow
• Figure out the exact angle and after some TIG practice, tack the elbow in place.
• Pay a pro to weld it up properly
• Finally be done with this monkey on my back.

Another thought would be to pay someone (TC Design, probably) to weld up the bolt holes in the manifold, redtrill them for the Bosch bolt pattern, and then come up with some sort of short, vibration-isolating mount.

I'd really appreciate your thoughts!

 

Two more alternate ideas:

The DUH:

• Remove and sell crossflow
• Buy standard radiator
• Use WF part as intended

The even-deeper:

• Cut the filler neck off of the crossflow
• Weld up the hole.
• Put the filler neck some other place
  • Inline in the long hose that runs from the back of the head to the radiator
  • At the back of the head through either my own design or someone else's existing solution.
• Use the WF part as intended
• Possibly reduce the headache of bleeding the cooling system

 

Closing the cap from the radiator and using a Tractuff rear water neck would have my vote. Having the cap at the *actual* top of the cooling system makes bleeding soooo much easier.
Additionally, cutting off the radiator neck and welding the radiator back closed is a very doable job for even a novice tig welder. Good thick aluminum, easy access, easy to pressure test afterwards.

 

I have to look over the Tractuff options again, but I recall that there's not a lot of stuff for the R40 head (K24Z3 motor). I'm not sure on the differences between the different heads back there. I suppose a message to them would be in order.

One more question - if I go that route, does it matter then that my overflow tank would be below the level of the rad cap?

I appreciate your input!

Ninja edit because I opened their webpage and immediately found myself to be wrong.

 

Although there will be a difference, I wouldn't expect it to be large enough to be dangerous. If you want to make sure you could always grab a log or connect to the ECU and see what it's doing, and I'm always happy to peek at tunes/logs too . Worse case scenario, it might need a percent added here or there, and I would expect the closed-loop and long term trims to fix that fairly quickly

 

The bolt pattern is completely different, 3 bolt triangle for the R40, 4 bolt irregular parallelogram for the RBB. But as you've now seen, they produce products for both. Expensive, yes, but excellent quallity.

I wouldn't think height would be an issue- the vacuum of a cooling coolant system should be enough to lift coolant 3-4", but I don't know that for a fact. Worst case you can move to a cappuccino washer bottle which fits(allegedly) in the wiper/cowl area. This will be level/above the cap and provide some positive pressure during cooldown.

 

I reached out to TrackTuff and got a reply from Robert later that day. I had had some questions about orienting the coolant overflow outlet and possible interference with the fuel pressure regulator that is several inches away from the head. Very nice and friendly, should be easy to order.

After some more thought, I realized that I over-complicated the most straightforward solution. I've ordered the 60 degree aluminum bend and will skip the idea of welding it to the flange for now. I'll just use a short, straight silicone tube to connect it to the manifold-side flange. Yes, it's an extra hose-clamped connection, but screw it. If I want to complicate things later, I'll whip up a new manifold-side flange (or modify the existing one) to fit a standard weld-on v-band flange and add the mating part to the tubing.

I may still make the changes to the cooling system, but I think I'll push that off for now.

Also, while screwing around with things, I realized I've needlessly held myself to using the big, threaded GM temperature sensor when it would be easier to go with a push-in solution since I'm N/A. This absolves me of having to weld an NPT bung onto my pre-throttle tubing.

KISS is hard work.

 

I still suck at estimating where an intake tube will land, but at least I've fixed the issue with the collapsing silicone elbow. It misses the radiator cap by an acceptable margin so the expensive water neck and radiator welding isn't immediately necessary. I can't remove the radiator cap without futzing with the intake tube, but I'll survive for now.


I've also bent up some tabs that I'll weld in place to hold the lower part of the intake tube in place. It should carry most of the weight of the throttle body, with nice rubber isolators to keep vibrations out of the throttle body.



They're carrying the weight in shear, which is probably not good, but I'm going with it.


I need to extend the throttle and intake air temperature sensor wiring. If I have the correct pins in stock, I should be able to get this done this holiday week. If I get frisky I'll try to figure out how to weld some metal back to make this hole the right size and shape.

I'm waiting on some Norma hose clamps - I'm a few clamps short.

I happened upon some cheap parts at the Carquest store I used to frequent - apparently it's closing and everything is on sale. So far I've scored an intake temperature sensor for $5, one of the VTEC solenoids for $12, a spare crank shaft sensor for $8, and one (sadly just one) NTK coil for $18. They're not the brands I'd ordinarily buy, but other than the intake temperature sensor, these will all be tested and then put in the trailer as spares. Sad to see another FLAPS close, but I appreciate the discounts.

 

I feel like I'm just about ready to stick a fork in this and call it "good enough for TV".

I extended the DBW and IAT sensor wiring and switched the IAT over to a standard Honda sensor. This absolved me of having to install a bung for the GM sensor, this just uses a 3/8" grommet from the local hardware store. The sensor connector is the same one that is used on the solenoid on the front of the engine, not the same as the other Honda 2-pin connectors.



It feels like it's taken a long time to make very little progress, but in reality, I've done a lot of "little things" along the way.

I also opened up the gas tank and inspected all of the fuel pump wiring for faults. I had a couple instances of the fuel pump cutting out for no apparent reason during the last running season. No faults were found. I've seen these kinks in the in-tank wires before, but after some very careful measurement with an ohm meter and some flexing, there is no fault here. Out of an abundance of caution I added some adhesive-lined heat-shrink over the top of the wire to at least keep the kinks in one shape.




I went so far as to add a second fuel pump circuit to the fuse/relay box. Now when I hit the "fuel pump override" button on the dash, a SPDT relay switches the fuel pump power source to a completely separate circuit breaker. It won't help if there's a fault between the fuse box and the pump, but it will help if the ECU is doing something screwy, or the primary circuit breaker/relay are faulty.

After doing all this, I hit the parcel shelf with some flat black paint to reduce the reflections in the back window. Actually, I hit it with satin black first, since I had a bunch of that and thinking that it'd be flat enough. For the life of me I can't tell the difference between Rustoleum semi-gloss black and satin black. They're both pretty damn glossy. I had about a quarter-can of ancient Krylon flat black, so that got used over the top. I hope this paint reflects on the window as poorly as it reflects on the painter.



I updated the IC-7 dash to the latest and greatest firmware, which required a bunch of re-work, particularly around the fuel level readout. I actually had to call Haltech tech support to get it worked out and I'm pretty sure there will be a bug fix coming out. Basically, I could get the software to read fuel tank percentage correctly, but the dash struggled to display it in terms of volume remaining. If anyone has similar problems, I can walk you through the solution, but it (of course) has to do with the fact that 'muricans like me think of fuel remaining in terms of gallons, and sane people think in terms of liters.

While I was screwing with this, and having learned a bunch of things from the Haltech documentation, I split out the "ignition" wire to the Haltech and attached it to the MicroPDM. When I hit the "on" button on the PDM, everything turns on and all I have to do to get moving is hit the starter button. Now I have a second button that I can use to turn off the motor, while keeping the dash and ecu alive for reading data or what have you. (previous setup was that I had only one button, which would shut everything off). Nice usability improvement.

I also spent a bunch of time making offensive hand gestures at the Italian software developers responsible for AIM's shitty products. God what an awful clusterfuck. But now I finally have data logging working with the Solo2 data + Haltech data + MSEL battery disconnect data.

Finally, I started gluing up the seat padding that's been sliding around under my butt every time I get in the car. It's still not done, but there is progress. And I can officially say that I suck at using contact adhesive.

 

Thanks for the cats folks! I sometimes feel like I'm yammering to myself in this thread, but I appreciate the indicators that at least some folks are following along.

As a bit of a discussion prompt, based on Roda's recent posts in his K-swap thread and looking at what folks are planning with their MTTC cars:

I'm currently sitting on RS4s with 2020 date codes.

My personal finances are going to be tight this year and my focus will be on putting down laps in HPDE4 at the NASA NorCal events, where my entry fee is kindly waived on account of working my *** off in Tech throughout the day.

What Would Miata Turbo Dot Net do?

1) Drive the current tires until there's nothing left, then make a decision.
2) New set of RS4s, because KISS.
3) New set of (name a sticky tire that I'll have to replace mid season), because I need to learn how to drive sticky tires.
4) New set of (name an endurance tire that will last me a season), because sticky tires mask poor driving.

The first NorCal event is March 1-2 at Sonoma. I don't want to spend the first event sliding off the track because my cold, ancient tires can't handle a mediocre driver in a 200hp/2200lb car.

 

How are the RS4's you have? When were they first used?

If they are 2020 date code tires that were first used in 2020 and have sat, outdoors, unused since then, replace them- they'll be hockey pucks.

If they are 2020 date code tires that haven't been used and are stored indoors, send it 100%.

Somewhere in between, up for discussion.

 

2020 date code tires that were first used in 2020. Used for half a season, then the K-swap happened and they stayed indoors in the Bay Area until 2023, when the car finally made it to the track again. They were used for the 2023 season, then sat out the 2024 season while I (slowly) replaced the blown motor. They've always been indoors, or in the enclosed trailer, in the cold-but-not-freezing Bay Area.

 

In my experience, from the time a tire is first used on track you've got maybe a year or two of good use before they really start to get hard. How were they in 2023?

Maybe goofing around at HPDE or whatever but these things will be very not fast.

 

I'll echo Ed's experience that a tire that sits for an extended period after being run a couple of times will be pretty bad. Storing indoors at moderate temps will lengthen the shelf life, but tires still age even when sitting. I'd probably mount up a new set and try to sell the 2020 tires on CL or FB. Some drifter wannabe would love to have them...

I've been a fan of the Toyo RR for a while... it's not the fastest, but it's not bad. They last a long time and are consistent though the life of the tire. For just a lapping tire where you're not restricted to 200tw for classing, I think they make a pretty good choice, and they seem to hold up to longer sessions better than the 200s. That said, I think the 'Super 200' choices today are pretty amazing compared to even a few years ago. The RS4 is now an 'old' tire in that hierarchy, though still a good endurance/hpde tire if you want to stick with a 200tw tire.

Last year I decided to try a set of V730s, and they're OK, but don't provide the confidence of the RRs and were a tick slower for me, so I probably won't buy another set. IMHO the RT660+ looks like a great 'sweet spot' tire for cost vs. pace and I would already have a set if I didn't really want to try the Nankang CR-S. After being out of stock since summer, they're finally available, and I just got a set mounted up, and will report back when I've got some laps on them. Either my V730s or Toyo RRs will likely get replaced with RT660+ ... whichever wear out first.

 

They did not inspire confidence. I made a lot of changes before the 2023 season, not just the swap, so I wouldn't lay the blame entirely on the tires, but in hind sight, I'm guessing that they contributed to a couple of incidents - spinning off T4 at Sonoma on a cold morning out lap that I was driving very gingerly; feeling like I was just idling through the Sonoma esses because I couldn't use more throttle without sliding off line, and generally not feeling like I could do the things I was doing in the previous configuration.

I wasn't expecting the RRs to get much love for longevity and I'm shying away from them at $250/pop, but maybe I can get some through the HPDE system this year. This is why I'm asking silly questions.

The RT660s, either vanilla or "+", seem like a strong offering.

There are seven two-day NASA events on the calendar this year. If I can make a set of tires last the entire season, that would be great. If I have to buy two sets of tires to make it through the year, that's not the end of the world. I'd rather spend money on more track time than going faster though.

So I guess the question is really - I'm going to spend money on tires soon. What's going to last me through at least seven days of 4-5 20 minute sessions each, while maintaining some non-embarrassing level of pace?

 

Probably nothing...

Looking at my notes, my last set of Toyos were slowing significantly on the 6th track day, and they've held out better than any of the 200s I've tried. In your position, I'd just get a set of RT660+ and see how it goes. I wouldn't buy the old version without a significant discount. Last I looked, the '+' were actually cheaper by $3/tire on TR.

 

I'm not surprised to hear the tires didn't feel great in 2023, and they'll be worse now.

I think Roda's advice is sound. Sell the RS4's cheap to someone who wants to burn em up, and buy a reasonably price 200tw. After a few events you'll know if you'll need a second set for this season or not. Since buying a second set isn't the end of the world, it isn't worth racking your brains about it. Sure You could buy new RS4's, that'd definitely last. Maybe conti ECF? I don't recall what size you're running to know if they're available in your size. might be worth looking into if you really do want to try and make them last.

 

I wouldn't even run those 2020 heatcycled tires. I've seen damn good drivers spin out with 3 year old heatcycled out tires, almost putting their car into a wall, so I'd take a hard pass on that.

 

15x9 wheel.

Am I correct that I should be looking at 225/45 sizes and not 245/40?