Turbo tune down?

[SquamptonRyan]

Tossing out a question to the brilliant deli community.

I've done alot of reading recently about turbos (and intercoolers, thanks for that Jesse!)

Everything I have read talks about how to get away with more boost, how to make more power, how to spool longer, how to cool the engine when the boost is cranked ect ect.

So what happens if you go the other way? Will turning down the boost cause the engine to run cooler and burn less fuel?

I know that back in the time of my L300 I wasn't about to give up a single PSI of boost. I didn't feel the need to try to crank more out of that lovely little mill, but the L300 definatly needs everything it has.

But now many of us have moved on to bigger beasts. My hilux with a 3L intercooled turbo runs about the same power/torque/weight/aerodynaic properties as your L400s. I would happily give up a HP or 2 in favor of engine longevity and a higher range on the fuel tank.

Thoughts? Jesse I'm lookin at you!!

Cheers dudes!
Ryan

[psilosin]

I put in a user controlled bypass to the boost sensor on my hilux surf which prevents the boost compensator from ramping up the fuel delivery with increasing boost. Great economy mod for around town driving. I get up to an extra 100km/tank.

[jessef]

I put in a user controlled bypass to the boost sensor on my hilux surf which prevents the boost compensator from ramping up the fuel delivery with increasing boost. Great economy mod for around town driving. I get up to an extra 100km/tank.

For the L300 a manual boost controller is your best option. Low in the city and dial it up when you need it on hills, hwy.

[psilosin]

If my 91 Surf has an electronically controlled boost compensator I am sure his 96 Surf does as well. An electric VSV valve place before it lets you block any boost signal reaching it...controlled from in cabin on the fly with a simple rocker switch. On = Eccono mode, Off = normal

Using an in cab user adjustable boost controller would work as well but isn't as simple. You wouldn't want to use a set it and forget it type or every time you decide to leave teh city you would have to pull over pop the hood and adjust it for highway. You would essentially be using the boost controller to do the opposite function they are usually used for. Normally you use a boost controller to trick the wastegate into seeing less than actual boost pressure so you can actually run higher than stock boost. Pluming it to the boost sensor (or on L300 or L400 to the boost comp diaphram) would trick the boost comp into thinking there is less boost than stock and thus provide less fuel creating an eccono mode.

Either way it is done note that you are still producing normal boost but since the boost compensator can't sence it, it is not providing the extra boost fueling. Keeping it on boost but with no extra fueling also helps keeps EGTs lower than they would be NA. Win-Win.

[strada-caster]

would this not make the engine run lean? standard air going in from the turbo, but you are limiting the fuel...

is this a good or bad thing for diesels?

[psilosin]

bad on a gasser, just fine and dandy on a diesel.

[yojimbo]

Aye, diesels have no mixture, there is air and there is fuel, and when there isnt enough air to burn the fuel you get smoke.

Sent from my HTC Desire Z using some tapas and some crusty baps

[strada-caster]

if that's the case, could you not get a variable valve (controlled from in the cabin) to vary the pressure from the turbo going to the injection pump while you're on the highway to find that sweet spot?

or am I taking this design too far too quick?

my electrical isn't too good, but i think a potentiometer would allow you to vary the current to an electrically controlled needle valve(or similar).

[jessef]

if that's the case, could you not get a variable valve (controlled from in the cabin) to vary the pressure from the turbo going to the injection pump while you're on the highway to find that sweet spot?

manual boost controller is your best option. Low in the city and dial it up when you need it on hills, hwy.

Boost controller in cab

[psilosin]

I am kind of surprised there isn't more interest in this mod. Maybe because it got over complicated too quickly? I can post pics of the setup on my Surf. If you are interested in econo mode to save money spending hundreds on fancy controllers is kind of backwards. A lot of the Aussie Surf guys take it even simpler and just put a $2 plastic micro-irrigation valve in the boost line and turn it on and off manually (too ghetto for me but you want ecconomy over flash...thats as ecconomy as you can get)

You can go all wild and make it fully adjustable on the fly but do you really nead variable LESS power in ecconomy mode? Not really. Its nice spending money and having variable control when over boosting above the normal factory setpoint for MORE power...need a little extra up that hill...tweak tweak zoom. Do both and you have the full meal deal.

ECONO MODE (boost comp disabled) -> single step to NORMAL MODE (factory settings ie wastegate and boost comp functioning as normal) -> multi-variable setpoint to SPORT mode (ie variable boost controller in line to wastegate to increase boost over factory *and may need to tweak boost comp to handle continued ramping up of fuel delivery as may have safety cutoff point below desired overboost level).

[SquamptonRyan]

Thanks for the replys!

psilosin, I`ll admit that I had to read your post 4 or 5 times before my simple bicycle meghanic brian could understand

I`ll elaborate more as to why I`m looking at a mod of this sort. My wife and I are planning a 15000 + km road trip beginning this march. The truck will be loaded down with bikes, kiteboard gear and paddleboards, and will be cruising at freeway speed for 8-10 hours at a time. Of course I`m currently doing all the regular mods (new cooling system, 2.5 exhaust, hi flow filter, snorkel) to help the beast run cool, but rolling thru baja or nevada in the heat I would love some more options to keep her running in the sweet spot!

the boost controller looks like the ticket for me. Will this work with my electronic fuel pump, or are these reserved for manual pumps?

cheers
Ryan

[jessef]

If you're doing all the driving in southern heat, I can't think of a better upgrade than the stock transmission cooler.

You can pickup a far superior cooler for under $200 at summitracing or mopar/mopac, add on a trans oil temp gauge and it will drop the monster heat in there considerably.

For the little added cost, I would do this mod before any other for a long trip like that. Small bucks to extend the trans life.

[psilosin]

I`ll elaborate more as to why I`m looking at a mod of this sort. My wife and I are planning a 15000 + km road trip beginning this march. The truck will be loaded down with bikes, kiteboard gear and paddleboards, and will be cruising at freeway speed for 8-10 hours at a time. Of course I`m currently doing all the regular mods (new cooling system, 2.5 exhaust, hi flow filter, snorkel) to help the beast run cool, but rolling thru baja or nevada in the heat I would love some more options to keep her running in the sweet spot!

Sounds like a fun trip.

If this is your end game...higher loads at highways speeds...then a turbo tune down is, maybe surprisingly, not what you want to lower EGTs. If anything, assuming current power and EGTs are OK under normal driving, you would want to increase the output from the turbo but without that increased boost reaching the boost compensator sensor.

How to get there...1) boost controller plumbed in the line to your boost sensor letting you decide from 0 to 100% of boost pressure reaching boost comp sensor and 2) either another fixed or adjustable boost controller into the turbo wastegate line or shim the wastegate spring (both methods will increase the maximum boost pressure the system will run at).

Example.
Stock Boost 7psi -> Wastegate shimmed or boostcontroller#2 setup to increase system boost to 12psi
Stock boost pressure reaching sensor = 100% -> use the boost controller to adjust to 60% (12psi*60%=~7psi)
Result = increased air volume, same fueling...should have lower EGTs compared to stock.
BONUS FUDGE:
chance to pass that semi...adjust back to 100%, boost comp sees 12psi and gives appropriate fuel bump...zoom zoom.

*I haven't used this mod for lower EGTs for any first hand experience, just passing on the theory. Personally, unlike econo mode, this seems like a lot of effort for the amount of effect but maybe it is awesome. I have seen this discussed over on ih8mud.com as a way to help keep 2LTE equipped Prados from cracking a head. I don't go there much these days but I would imagine there should be a healthy number of people with 1KZTE equipped Prados (and Surfs) who might have also already done this or other mods to help stay frosty that might have first hand knowledge how well it works.

And if it is an automatic, as Jesse said an aux trans cooler is a no brainer.

Also something like Devil's Own water (or water/meth) injection is supposed to lower EGTs significantly. Not sure if I buy into it but some happy customers on the Aussie Surf forum site and Devils Own forum. Pretty easy to setup and water is cheap :)