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Unsprung weight, the silent addition.

It's been a year since I jumped to 39s from 37s. The unsprung weight rocketed, from 70 to 89lbs. A whopping 19 lbs. They say that 1lb of weight is about 1/10 of a second slower in acceleration. I was starting to feel the weight. This wasn't an issue on 37s but with the taller rotating mass has been killing it. So why don't I go back? Because we've gone too far!

I hope to continue driving on the 39s with supporting mods like an front e locker (when money permits) and upgraded the axles to the 934 hubs and 300m axles. And in the rear, ford 9" with the 3/4 link setup. In the meantime, doing what I can to improve little by little. Jumping to forged wheels helped me drop 4 lbs in each corner! This is crazy when it seems like industry standard for a cast formed wheel is at least 25lbs each. The Titan T-AK1 are 20.4lbs each! They use anti slip tire bead seating for low PSI. And did I already mention they're forged and stronger than cast?

Titan T-AK1 17x8.5 -8
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Wowza, that's a lotta tire!

3,652 Posts
Discussion Starter · #345 · (Edited)
I skipped testing before the mods because who wants to see stock numbers amirite? By the time I decided to proceed with my s/c install, it was easier to start disassembly. I got my current dyno measurement as with all the mods. Didn't quite break 300 hp but let's just say it's well on its way there. I haven't touched much of the exhaust system which may unlock some more achievements. So far the supercharger with 2.7” pulley is a definite boost of 36% hp and 29% tq increase from stock reported numbers minus the drivetrain loss. The ending figures don't mean much with the change from dyno to dyno. But in the graphs we can see places for improvements or inefficiencies.

There is some need to open up the power band from 4k rpm on. The s/c is starting to work out of the efficiency range with the smaller pulley or possible bottleneck due to stock header and y-pipe. Pretty close to full torque at 2900 feels like a fat rocket ship. I think TRD models should have received this upgrade as the performance would definitely put it a step above.

A few mods to come.
JBA shorty headers
DT y-pipe
NST supercharger pulley
New ECU?

Stock reported
Horsepower239 hp @ 5200 rpm (191hp with drivetrain loss)
Torque278 lb-ft @ 3700 rpm (222tq with drivetrain loss)
After s/c mods (2.7 pulley, VKH22 plugs, ripp coil packs, urd exhaust gear, 2.5" afe exhaust)
Horsepower290 hp @ 6000 rpm (261hp with 10% correction for Dynapack)
Torque319 lb-ft @ 2900 rpm (287tq with 10% correction for Dynapack)



3,652 Posts
Discussion Starter · #348 ·
These past couple weeks had me chasing a couple trouble code gremlins. Reminds me to keep it simple where I can. Reminds me of how much stuff we have hooked up to our cars that we don't need. Reminds me that sometimes what's good in theory, not always in practice.

Tire Wheel Vehicle Plant Automotive tire

While I had some hard start issues before in the past (always random and never duplicated), three weeks ago, it completely stalled upon starting after running an errand. I got her fired up again and was able to limp back home 8 miles. I kept getting code P0351-P0356 which is a coil malfunction on primary/secondary signals on all 6 cylinders. It's really generic that it could be wiring, coils, ECU related, and anything revolving around the fuel system which would cause stalling. So you go over everything. Check spark is arcing. Check there's fuel going from the pump, fuel to the injectors. Is there a leak in the system? Shake the wiring harness. Check the connectors. Remove passenger kick panel. Wiggle all ECU components. Go through each EFI/fuel/ignition fuses. Same trouble codes. Still stalling after starting and idling. So I am getting fuel, spark, no misfires.
Motor vehicle Automotive tire Automotive fuel system Automotive exterior Coil

10k miles ago I had swapped out my coils for aftermarket performance Ripp coils. Certainly not those, I thought or hoped. Why would it set off a code for all 6 coils. They were brand new. So I set out to swap them. I pulled a whole bank on the passenger side and swapped my old Denso coil packs in with all 180k miles behind them. 3 coils swapped out and no stalling. No trouble codes.
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Ugh. So I was still skeptical. Swap the Ripps back in, one by one. Stalling occurs. A~ha! Located the troubled lonely coil. Tested them for resistance. Shows similar between the good and bad coils..doh. When the ignition is hot, my assumption is the issue makes itself apparent. Otherwise cold starts don't show the issue until the car warms up. I'm not questioning the reliability. The coils performed well for 14 months and 10k miles. I just probably hit a lottery on 1 in thousands of coil packs to make it to coil pack heaven. At any rate. I'll replace the bad one and save it for another engine build.
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Now if you ever seen P035x codes, don't be afraid to check that specific corner but getting all the codes, don't worry. Toyota has a way of putting the secondary coil return signal back to a single wire to the ECU. What a not so fun way to learn. :cautious:

Anyway thanks for reading this far. Here's a bonus:

Two Toyotas from Japan in America. Born twenty two years apart. Different philosophies of use. One all motor and other one supercharged. Both have made their mark in history. Yet they still have a long road ahead..
Tire Wheel Automotive parking light Car Land vehicle

3,652 Posts
Discussion Starter · #350 ·
Excellent trouble shooting James!
That rabbit hole could have gone on and on and on...
I did stick my head down the rabbit hole plenty. Pulled the ECU management for malfunctions. Replaced the fuel pressure regulator.

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3,652 Posts
Discussion Starter · #352 ·
I’m just going to leave this here:
Thanks, I didn't see this before. Looks like he had worse luck with it giving up sooner than mine. Though I wish there were a real answer. I offered to ship mine back for further r&d but they said they had one already. I assume that's more than one after seeing this video. Just hope that gets ironed out. The coil packs did feel better than the Denso coil packs in my opinion and I'm still gathering data on a hard number for the MPG difference (if any). I find this info may be useful for others that have troubleshooting issues with stock Denso coils. I've located similar issues/accounts with OEM Denso coils as well so I don't think this is isolated to aftermarket coils anymore. It's just that people didn't have to troubleshoot or they didn't know what to look at. And just like the video, all research points to the similar points of interest to debug the issue and most likely failed attempts. I assume they just took it to the mechanic.

3,652 Posts
Discussion Starter · #353 · (Edited)
Everyone probably thinks I'm assbackwards. I've put engine and transmission cooling on the back burner for long enough. I went with dual pass heat exchanger design for less turbulence therefore fluid flows back a little easier to both the engine and transmission. My understanding is that the traditional tube and fin coolers have more pass/turns to create more turbulence to pull out heat. Heat sinks for the transmission are supposed to better when little to no air flow is present but when moving, will fully benefit. Also I preferred not to stack in front of all the radiators since I also have a supercharger intercooler already.
Gas Automotive lighting Technology Auto part Font

Font Technology Auto part Gas Electric blue

The black plastic board is mock up for the metal bracket I'll "fab". Enough space for an engine oil cooler and automatic transmission heat sink.
Rectangle Composite material Tints and shades Gas Metal

Automotive lighting Automotive tire Motor vehicle Hood Grille

Tire Wheel Car Automotive tire Hood

The engine oil cooler is an All Star Performance deck mount oil cooler (15x4x3.3") tube and fin cooler that is dual pass with -10AN ports. This allows you to configure any number of ways with 45, 90, 120° ports. With other coolers, the ports are usually 5/8" push-on or ports that point up and down, going against gravity.

The transmission cooler is a Moroso cooler with integrated filter. The heavy duty dual pass version was too long at 18" so I had to machine this one down to about 12".
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Waiting on push lock AN fittings to come in the mail. Unfortunately, I had to go overseas to order the parts since they had a better selection. I like the option of push lock fittings and clamps. Repairs would be easier on the road IF there ever was an issue, ie. no need for a bench or vise to fit the hose to the aluminum fitting. The coolers are made in the USA.

Will update when the bracket is cut, radiators mounted and lines ran.

5/28 bracket cut. Holes need to be drilled but that's the easy part. Git'er dun in the work shop.
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3,652 Posts
Discussion Starter · #354 ·
Not my best work but I got most of the mount chopped out and drilled beforehand. My friend finished slotting and making a bracket for the thermostat. Pretty happy with the way this came out. Just took a couple years to plan hah. But I had it in mind and made it happen!
Still need:
-vent the front skid for some decent air flow
-lines measured and cut to fit

Wheel Tire Car Sky Vehicle

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