Towing with a Supercharger

[Marazzito]

Now that the TRD Supercharger for the 4.0 is finally being released I am highly considering it.  The 4.0 really is a great V6 and has a really good amount of power for towing within it's limits.  I tow on the uperend of my Tacoma's limits nearly 6,000 lbs.  I have been very happy with the Tacoma's towing performance for what it is (it is not a Tundra).  I can maintain 60+ on any grade or mountain pass I have towed over, including both HWY 50 and I-80 to Tahoe (sometimes in 3rd gear really letting the engine spin, but it is happy to work) .  My only problem is, if I get stuck behind a slow moving semi, passing can be a chore at high altitudes.  I think a Supercharger would give me a nice little boost (no pun intended) for times like these.  I do tow rather often.

So here is my question... my understanding is that the 4.7 was having problems handling the extra boost of the Supercharger while under heavy load and there was quite a bit of engine failure from towing with the SC 4.7 and that is why they ultimately discontinued the SC for the 4.7.  Is this a common problem with SC engines?  Should I be concerned? Do you think Toyota learned from past experiences with the SC 4.7 and would not realease a SC for the 4.0 if they weren't sure the same problem would occur in the 4.0.

Of course I wont make a final decission until some actual numbers and pricing is released but I would love to hear some feedback and oppinions on a SC 4.0 while towing.

Reliability is a must because I plan on towing from California to Utah in May so I don't want to compromise reliability at all.  I also don't want to turn this into buy a Tundra post, because I love the Tacoma and it is a great daily driver/weekend warrior.

Thanks for your input!!

[jmo]

Can't speak to how the 4.0 engine would handle it, but if you think about what a supercharger does: it pushes compressed air into the air/fuel mix which allows more fuel to be ignited per stroke (while maintaining the proper ratio) hence giving you more power. It's the same technique used by turbo chargers, the difference being the turbo reuses the heat from the exhaust to spin a mini turbine that drives the compressor (better for fuel ecomony, but response is proportional to engine speed) where as the compressor for a super charger is run off the engine itself - hence immediate response but hurts fuel economy (not that your concerned with that )

So, the bottom line is you are stressing your engine/pushing the envelope of what any engine can handle by using one. Sounds like in certain situations your red lining your V6 as it is, and your just going to stress the engine even more with the SC...

Finally, I would also be concerned with overheating the transmission with the load your towing, might want to install a transmission cooler since you don't want to upgrade to a tundra...

Hope this helps,

jmo

[Marazzito]

I have a manual transmission, do you think a cooler is really needed? Also I am not redlining the engine, if I dropped to 2nd at 60 I would be redlining the engine and I have not done that (I suppose that would get me passsed slower moving traffic on the steep Mountain grades, but something about 2nd on the HWY just doesn't sit right), but I am at the low 4,000 rpm range, which is where the 4.0 makes most of it's power. I would think I would have enough power with a SC I would not have to be in 3rd quite as often, But I could be wrong. Also, I have nothing against the Tundra, it is a great truck, it is just way to big for the parking garage where I work.

Thanks for your input though!

[Corban_White]

First, you shouldn't need a tranny cooler w/ the manual. Second, depending on the amount of boost the S/C puts out and the altitude you are towing at could affect your worry of damaging the engine. For example, suppose you are towing at 5000 feet (a relatively low mountain pass) and suppose also that the S/C puts out 2.5 psi of boost (it probably puts out more but this is just an example). At this altitude the ambient air pressure is ~12.2 psi whereas at sea level (where the truck is designed to run) the ambient air pressure is ~14.7 psi. Therefore, at 5000 feet and 2.5 psi of boost, you would really only be exposing the engine to the same pressure it is designed for. As you continue to ascend, the "boost pressure" needed to develop 14.7 psi in the engine goes up. So, let's say that the 4.0 will operate reliably under heavy towing loads with up to 18 psi manifold pressure. This would mean that at sea level you could safely operate @ 3.3 psi boost and at 5000 feet you could safely operate @ 5.8 psi. Essentially, the engine doesn't care what the boost pressure is, it only cares about the MAP (manifold absolute pressure)-which, btw, the scangague II can measure (on most vehicles) according to their website. Now, having said all that, I must say that I do not know the design parameters for what MAP the 4.0 can handle, nor do I know the operating psi of the supercharger. The numbers I used were strictly theoretical (except for the altitude/psi numbers, which are approximate). In order to know exactly what kind of boost pressure can be run more data would have to be obtained (specifically, what is the max MAP the 4.0 can run at for sustained periods of time and under large loads). However, we already know that that number is AT LEAST 14.7 psi so, w/o any further research, you know you can use boost (either from a turbo or the S/C) to compensate for the pressure drop associated with altitude gain. Hope this helps.

[jmo]

Originally Posted by Marazzito

I have a manual transmission, do you think a cooler is really needed? Also I am not redlining the engine, if I dropped to 2nd at 60 I would be redlining the engine and I have not done that (I suppose that would get me passsed slower moving traffic on the steep Mountain grades, but something about 2nd on the HWY just doesn't sit right), but I am at the low 4,000 rpm range, which is where the 4.0 makes most of it's power. I would think I would have enough power with a SC I would not have to be in 3rd quite as often, But I could be wrong. Also, I have nothing against the Tundra, it is a great truck, it is just way to big for the parking garage where I work.

Thanks for your input though!

Right - manual your okay, I've been driving a tundra with an automatic for slow long now that didn't even enter my mind... Corbin makes some good points about the SC helping return you engine horsepower to where it should be at altitude.

jmo

[Marazzito]

Thank you both for your input! I kinda figured that the Supercharger would restore lost HP from altitude which is my main concern. Thanks for confirming that. I believe the TRD SC is at 6.5 lbs of boost if I am remembering correctly. Now I have one last question... I currently have stock 3.73's, I could switch to 4.11's or 4.56's in both axles for less than the cost of a SC. I am assuming that the lower gears would hurt the MPG's less than a SC, would this be correct thinking? Would 4.56's be overkill? Would 4.11's not be enough of an increase? Or would I be better off with the SC? Thanks in advance!

[Corban_White]

I believe that the gear change will hurt your gas mileage more than the S/C. This is because the gears will decrease your mileage by the same (or close to the same) percent that they change (ie 3.73-4.56 would equate to an approximate mpg drop of 22% (give or take) since this is the difference between these gears. The 4.11's would be somewhere in the middle). OTOH, the S/C, while it takes some HP to turn, it also provides HP (hopefully a net gain at all rpm) and while this might seem like it would take a lot more gas, the decrease in mileage is actually quite small because of the smaller throttle opening needed to maintain a given speed. In fact, the similar concept of a turbocharger can actually provide an increase in gas mileage (in some cases). I would also favor the supercharger for another reason aside from gas mileage. I assume you don't only drive the taco while towing and if this is the case then with the trailer unhooked the drop in gears would (in my opinion) be a severe detriment to the Tacoma's driveability. you have the manual (like me) and first gear is already plenty low (and I have 285/75/16's!). Depending on which set of gears you got, it would be like loosing sixth or even fifth and sixth gear! You would, however, have no problem at all starting in second (like my '91 GMC). Of course, disregard all of this if when the Tacoma is unhooked you use it solely for rockcrawling. But if this was the case, you wouldn't have the FJ. anyway, thats my .02, hope it helps.

P.S: before you drop the cash on the super, check these guys out: Squires Turbo Systems - Turbocharged Innovation!
I know they don't list the 4.0, but they do have a universal and they may have/be developing an engine-specific kit (their website is sometimes slow to update-too busy having fun I guess)

[Marazzito]

Corban White... Thank you very much! That is exactly what I was looking for. So gears are out. I think I will check out a TC as well as the SC, I will give them a call. Yea, the Tacoma is not soley for towing, if it was, I would have a Tundra with the 5.7. The most rock crawling it see's is the gravel road before the Rubicon or the occaisonal fire trail on the way to a camp site. The 4 wheel drive is mainly for driving in the snow. The FJ40 is well built for my Rock Crawling needs (I need to get some new pics with the new mods as well as some Tacoma pics).

[rlehan]

I am not aware of any turbocharger or any supercharger other than the TRD that is legal in California. They need to be tested and approved by CARB and come with an EO number to be legal in California. Be careful what mods you do to your motor in California or you could find that you wasted a lot of money.

Rick

[Marazzito]

I am definetly leaning hard towards the TRD Supercharger. As soon as it comes out and we see some real numbers I will make my choice.

[05Octopus]

I had the S/C on my '99 3.4 V6 (5spd manual, 4wd, Xcab, TRD O/R). I'll say it made a world of difference for towing and running at altitude. However, I will say it was not without effort to make it work right and the whole 'bolt-on' concept that TRD tried to sell was a little shy of the truth. If you go back and do some research you'll find a ton of history on lean out at high rpm and ping issues at low rpm. TRD updated things with 7th injector kits, etc. in the mindset of bolt on, however, nothing would make up for bigger injectors, fuel flow and a remapped timing curve (since knock sensor intervention didn't occur at low rpm to quell the ping).

With that said, I'd recommend holding out a year at minimum unless you like being the guinea pig. It doesn't sound like it though based on your desire for reliability. I'd expect TRD has learned a few things since the 3.4 and 4.7 kits.

Some things that the 4.0 ECU may have a leg up on the 3.4 is the wider octane flexibility to start out with. It'll run on 87, but prefers 91 and up. In factory bolt on state, my S/C 3.4 only ever ran right on 94 octane (not available in CA readily).

But, with the rumors that the new S/C comes with an intercooler (3.4 needed it for extended boosted running while towing on grades), an ECU reflash, etc.... it may not be too bad... may have to think about it again.

I'll will say the S/C 3.4 pulled better especially at low (1500RPM) to 4000RPM than the 4.0L. A S/C'd 4.0L should be a hoot.

[Marazzito]

Wow, I am surprised that the 3.4 with a Supercharger pulled better than the 4.0. With that being said, the 4.0 S/C should be killer. Thanks for the added input, I am definitley leaning towards the TRD, and will most likely wait for them to get the bugs out. One thing is fur sure, I will definitely need a trac bar. With out the S/C you give the 4.0 much gas and the wheel hop starts. I am not a racer, I do have a heavy foot though from time to time.

[Captain J]

Any new news on when the 4.0 SC is supposed to come out for the tundra?

[Marazzito]

Originally Posted by Captain J

Any new news on when the 4.0 SC is supposed to come out for the tundra?

I would email TRD. I know it is finally out for the FJ and the Tacoma. I am sure a fit kit for the 4runner and maybe even the Tundra will be next.