Overland Torque Tune (OTT) by Overland Tailor

I'm interested in this general topic -- modest torque/power physical mods for a NA 1GRFE engine. I plan to install both 3º exhaust cam gears and either a 1/2" or 1" IMS on my currently-stock 4.0L. I have the OTT tune now, so after installing the mods I would then request optimization of my OTT tune to suit.

I wonder what the performance differences are (if any) between a 1/2" vs a 1" thick IMS? Would a 1" IMS bring the torque curve even lower than a 1/2"?

I don't have feasible dyno access nearby but I might try doing some carefully-controlled improvised before/after power testing on a section of deserted asphalt airstrip. 10 or so 0 to 60mph runs, averaged, in calm air conditions w/ careful attention to keeping as many other variables fixed as possible. Rest time between runs, vehicle weight, outside temp & humidity, road surface temp & moisture, tire pressure, fuel quantity & age, etc.) Also w/ OBDII logging using an MPVI2+ and/or Autel 906TS scantool.

 

The rev-hang delete mentioned in the discussion you're referring to is a 2G specific thing. There are specific maps available in the 2G that are responsible for the "rev-hang" and we can manipulate them to in a variety of ways. However to simplify things we offer 2 standard settings. A full delete and a 50% delete, where we reduce the effects of the "rev-hang" by 50% through mapping changes. The full delete from our testing proves to be a bit much for most folks and makes stop-n-go driving in traffic or tight parking lots a little clunky. 50% delete is the sweet spot for most folks. It feels "gone" but you don't have the side effects at low RPM/slow speeds that a full delete can have.

We haven't specifically tested the available spacer for the 3G Tacoma. However, we'd be happy to do it. If anyone on a OTT tune that has the spacer would like to meet with us in SLC, UT or Birmingham, AL we'd be happy to get you some numbers for your spacer.

But it's safe to say the longer intake runners (due to the spacer design) will shift the power curve down lower in the rev range. How much is hard to say. There are a number of peer reviewed papers that cover this topic. I encourage you all to read up on the topic.

Similar to my reply above, it's going to depend. I haven't specifically dyno'd the 2G spacers but there is some data on ACIS that will illustrate the point that longer runners shift the powerband lower in the rev range at the expense of high RPM power.

This was done by @Torspd some time ago. He manually manipulated the ACIS valve (2G's are vacuum driven, where 3G is driven by a electric motor).

In the above dyno there are 3 runs but to illustrate the effects of runner length pay attention to the SOLID lines representing ACIS configured in "long runner" mode, and the dashed lines in short runner mode.

You can see the clear advantage below 4200RPM with the additional runner length. You can also see how badly the additional runner length hurts the power above 4500.

What I can say is the effects of the spacer will unlikely be this dramatic, but the principle is the same.

 

Time-permitting, please share a few of the titles/authors, and/or direct links, DOIs, or similar to some of these papers.

Interesting, thanks for re-sharing that. This is my arm-chair interpretation:

It would seem that a 1/2" vs 1" IMS may not make that big a difference since the overall % change in effective runner length between those two IMS's is fairly small. Sort of like lengthening a low-register pipe organ pipe a little bit is going to bring that particular tone (musical note) down some, but only proportionally.

Difference between 1/2" and 1" IMS perhaps also likely to be proportional & gradual -- unless it happens to be that either of those two IMS's brings the total runner length to a spot where there are higher-order (modal) resonances which cause unexpected peaks/dips in the power or torque curves. Due to the complex geometry & dynamics of the entire intake/runner/valve/cylinder system, impossible to predict this except maybe with highly sophisticated aerodynamic simulation software.

 

I think you're on point sir!

 

Thanks for that. Good information to have.

 

I’d be very interested in the 50% rev hang mod, or better still an instant drop by 500rpm then shorter length hang. This would almost ensure perfect rev matched shifts for me every time.

 

I installed the spacer on my whip, and live in az. The spacer has helped, in my opinion. The truck hangs in six gear more, across the board, and performs more responsive around 3000-3500 rpm range - 4th gear up and down the mountains. 3rd gear around 70mph has always allowed me to Nascar up the steep grades, so I can't speak to any top end loss there
I have 4.88's, which helps too.

For a couple hundred bucks and a few hours of work, I think it's worth it.

You haven't done any exhaust modifications by chance, have you? I've seen a few folks speak to restriction by the crushed y pipe, and one user reported 30hp/10tq on the dyno with afe's full exhaust replacement. I wonder if modifications might improve performance a bit more in 4th, on steep those grades.

 

At 360whp, the 3G makes about 5-8whp from a low restriction cat-back exhaust. We've tested these with a y-pipe and noticed slight improvement even with the factory cat-back installed on our shop truck w/ the Magnuson. We will have data on a y-pipe+catback combo soon. Our baselilne data was performed on a standard blend fuel and we're still getting winter blend fuels here in UT.

I don't think the 30hp claims will be substantiated, but I wouldn't be surprised for 10-15whp at the 370+ power level. If we tap 390whp (for a 20whp gain) I'll be pleasantly surprised.

 

Thanks for the supportive info! The real question, for me, is how is real world driving affected. I recall seeing dyno numbers for the mk3 (I think?) Y pipe, without cats, showing improved torque down low and claimed noticeable improvements.

What more can be squeezed out on NA and is it worth the cost, is my circular thinking haha. Those dyno numbers with your tune and supercharger are intriguing but too costly for me to justify.

Thanks for adding to the discussion!

 

The 2G’s big restrictions are the intake and factory manifolds. Cam gears are great too! Addressing those on a 2g combined with a tune (even with stock y-pipe/catback) will transform the truck.

The 3g doesn’t suffer from a choked up intake system like the 2g. There’s almost 10whp in the 2g air filter alone! Even with the stock airbox! Our testing showed *0* difference in a low restriction intake vs stock at 360whp. I wouldn’t (and don’t) run anything different than a OEM intake on a 3g especially N/A. If you want to change your induction tube no biggie.

I haven’t confirmed on the 3g yet, but I believe the biggest restriction from a bolt on modification standpoint is the factory dumptubes. Followed by the y-pipe then the catback. On a N/A truck I wouldn’t necessarily bother with the cat-back from a $:HP ratio. The problem with the others is they contain emissions equipment.

I do think the spacer is a decent mod and would benefit the majority of 3.5 owners with how we observe most using their vehicles. I think any power lost up top from the increase in runner length is worth it’s weight in gold if it’s made up in the low end.

 

I see. The 4.88's will be the big contributing factor there, but if you noticed an improvement then you can't argue with that. I haven't done any exhaust work yet, mainly because I want to avoid any noisy shit. I need to get it rerouted for clearance, at some point I will start looking around for something that will perform well otherwise I'll leave stock.

 

I have my original cable from Orange virus and getting it reregistered so I can use it to load current tunes.
How much is it for a tune file for a basically stock truck..?
Aluminum front bumper, sliders and fox 2.5 Coil-overs.

 

$315

Send us an email to info@overlandtailor.com and we'll get you sorted.

 

I had my (mostly) stock 2017 OR MT DCSB with 124k miles flashed with OTT a couple of days ago in Buffalo, NY. Chris was very upfront about the process before I met up with him, and during the flash procedure. He asked questions about my truck, and offered to answer any questions that I might have about the tune.

Initial impressions during the test drive were great! The throttle was significantly more sensitive. I'm pretty sure that we went with mild/medium throttle response. Immediately, I noticed that the truck had more low end torque, and that power was delivered much more linearly than the stock tune. I embarrassed myself with poor shifts a couple of times... Apparently, over the last 124k I had picked up a few bad habits.

The drive home (I live a couple of hours away) was a treat! I was able to utilize 5th and 6th gear at 55-60mph. Prior to OTT, 5th gear lugged until 65-70mph and 6th was only useful at highway speeds on flat land with no headwind. I can't say that I picked up any fuel economy, but I'm pretty sure that I didn't lose any, either.

Driving around since the tune I've found that I don't need to downshift quite as much. The truck has enough power to make a turn then come up to speed without the previously required downshift. The truck feels and drives as it should have from the factory.

The only thing that I don't love is now the short first gear and tall second gear are more apparent. First gear is super short, requiring a quick shift to second almost as soon as the truck gets moving. Second gear is too tall to just start out in second. Note, however, that this isn't a problem that is caused by OTT. Rather, it's an issue that is highlighted by OTT.

Initial impressions are quite favorable, both for the tune and for Chris with Buffalo Speed. When I have more miles behind the wheel with OTT I'll report back.

 

That's a good point about OTT accentuating the tallness & large gap between 1st & 2nd in the manual trans. I hadn't considered it before but it makes sense that the extra torque down low / early in the rpm band causes 1st to pull even harder than stock. With OTT it does take an even lighter gas/clutch foot to handle 1st without lurching, no doubt also due to rev-hang reduction.

I don't mind it as it is a truck, after all. I think they made 1st gear so low in the manual to give the clutch & engine the best advantage when starting heavily-loaded on an incline.

Reverse gear is another story.. for that I consider that the 2LO mod is required to be able to safely back heavy trailers upslope on dry asphalt without burning the clutch. Toyota could've added 2LO capability into the firmware of the 3rd gen without any hardware modifications. My guess is they opted not to in order to avoid adding further potential operational confusion for the average Taco driver who may seldom or never need 2LO.

 

OTT is now available for 2005-2009 4.0L 4Runner! With 4.7L support coming very soon!

Using the the knowledge and experience gained from years of 1GR-FE development in the 2G Tacoma, we're now able to offer our base and custom calibrations for all of your 4th Gen 4Runner needs - from stock and beyond.

Calibrations are available only through our network of authorized tuners.

https://youtube.com/shorts/AtEMcSJrep0

 

Ooo, I know there aren't a lot of s/c 4.6L 4Runners out there, but would be very cool to see some tuned numbers on one!!

 

John in Albuquerque did an update on my Tacoma, great guy. I love this tune, if your in NM, give John a holler

 

The 2nd gear bog issue is super annoying if you like to get out of 1st as quickly as possible. I've found it's best to just run it up to 3500rpm to avoid hitting 2nd anywhere below 2K RPM unless you're going downhill. If you're below that, and going uphill, the bog / lurch can be super annoying. I've been told only some trucks do this, it has definitely been an issue with mine. I live at higher altitude and frequently drive around 8000ft so that probably exacerbates it vs. sea level. It's happened with the vehicle since it was new.

 

When I got this truck (used, at 60K miles, bone stock, no tune) I don't recall it having very much lurch. I think the lurch really started when I added ~450 lbs, distributed ~110 lbs basically cantilevered way off the front end (ARB bumper), & 340 lbs or so of metal utility cap + lumber rack on the back/middle, & then added a low-range torque-emphasizing tune.

The stock suspension is both under-sized for the added weight, esp. out front, & also fairly worn (70K miles on it.) Like a jouncy old sofa the truck naturally wants to get into a resonance mode at low speed & high torque which leads to disconcerting lurch-jerking.

Choice of gear lubes, both transmission & rear diff, probably also has something to do with it because the lurching is much worse when the truck is cold. Currently running Lucas

$29 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 GL5 in the rear diff & Redline MT4 in the manual trans. The Lucas product claims to be compatible with limited-slip diffs but maybe I should also be adding separate/extra LSD additive.

I suspect that if & when I do a proper & complete full suspension upgrade to properly-tuned 2" or 2.5" high-quality coil-overs & Dobinson rear leafs + shocks, the low-gear lurching may abate or disappear entirely.