fuel economy...(lack of i expect)..never FI a petrol engine before

[zen]

ok..waiting for the flywheel to turn up now,and i was thinking,how easy it would be to make the headers i need to make face up and around to a pair/single turbo...say just running 8psi max (standard engine)..i want max torque not max hp so i guess maybe a pair of smallish vnt's (hello ebay)....(i know a supercharger would be best suited, but the engineering work would not be done in the 4 weeks it will take to get the flywheel, and i need to be using this truck now not next year.)

however....fuel here in the uk is way expensive, i need this car (range rover) to be affordable, i will be putting many a mile on her....so..how badly will this/these turbo/s kill the economy...yes i know it depends upon my right foot, but on my current rangie (diesel though!!) adding the turbo added economy...is this gonna happen on a petrol (lpg will be used too) motor, or is it going to cripple my wallet more than my wife and daughter??.


doing the engineering will be no probs,(done 3 diy turbos,but all on diesels)) though a pointer in which turbo/s one can find on ebay (ex diesel maybe as there are loads of them and this is a buget project (atleast it was ment to be )) that you have found to work well would be helpful...(need low end boost more tham outright top end hp)

oh, how much boost will a stock uz take if in good condition with stock ecu??( have 2 engines now,just in case i kill one) (maybe 3 by time hols over) as they are rather cheap here..ie last one sub 80k miles complete with ecu and un cut loom £80 taken out for me, ain't ebay great!)

thanks

 

[-Nemesis-]

It really comes to driving style like you suggested. The main FI theory is more power = less throttle. But when you have a TT V8 you'll use lots heheh...

Boost = air. To compensate it needs more fuel. So more boost and more throttle equals more fuel.

Cruising though, if it makes the power effortless and you can resist getting into it, it should improve the economy a little.

 

[Zuffen]

My stock 1UZ in my Dakar gave 17 litres/100k on a run to Canberra and back (read motorway/freeway driving).

My supercharged engine would get through around 25litres/100k in the city but I can't tell you the motorway economy as it didn't run long enough. I would guess around 20litres/100k.

 

[-Nemesis-]

17 is quiet high, how heavy is it?

Mine stock used to get around 13 on the highway at 2.2t and 33x12.5" muds. Currently I think I'm getting around 18/100 on LPG and boost

 

[Death By Bass]

my celsior did an average of about 19litres per 100k's driving from Adelaide to Bordertown and back one night :S

possibly something to do with my driving style.

 

[Tonyd]

Hi Zen,

Been lots of discussion on here re twin turboing and my understanding is that a pair of GT28's and intercooler running up to 7 psi should be ok on stock engine and ecu.

Any more boost that that requires an aftermarket or piggy back computer for fueling purposes, bigger/ additional injectors and a higher capacity fuel pump.

I'm looking to do a "scrapyard challenge" twin turbo on the next Cobra , initially running standard ecu sub 7psi and then when I've learnt a bit more increase boost whilst using a piggy back megasquirt system to control secondary fuel injector/s when the engine is on boost.

Hopefully this will give heaps of power and torque when on boost ( basically using a large capacity intercooler and lots of additional fuel) and excellent economy when driving about off boost on standard factory ECU settings.

ATM I'm getting 36 mpg out of the first Lexus engined Cobra so its would be a shame to lose its economical cruising ability.

Cheers,
Tony

 

[zen]

well...well...interesting and what i am aiming for i think...(though 36 mpg will be impossible with my 2t rangie!!)

just bought another engine on ebay..(£80 including uncut loom and ecu!85kmiles), but its a latish one, so thin rods so 8psi will be the max i will be going ..now to find scrap heap challenge style 2 gt28's..so what runs them i wonder..or maybe a pair of 1749 or2052 vnt's (diesels??)

i hope to do this conversion for not alot (if i can find the turbo's) as so restoring modding and fitting 1uz into old range rover is adding up the penny's!though the engines are really cheap!(unlike the flywheel etc.)

 

[Tonyd]

Hi Zen,

Seems we are cut from the same cloth........ie never mind the quality feel the width. I just love seeing how little I can to spend to create a frankenstein engineered monster.

When you find your turbo donor vehicles let me know as GT 28's are it seems quite rare and I'm unsure as to whether diesel turbos can cope with the heat from a petrol engine, and also if they will be able to feed the 4 ltr lump in the higher rev ranges.

I've driven a few Turbo's in the past ( including a 2.5 bar boosted ex works Audi 5 potter) but I've never put a turbo system together myself.....yet.

Cheers,

Tony

 

[Merxus Benz]

At 6psi the turbo and engine will be working at peak efficiency and economy will improve slightly over N/A After this the compressed air begins to become super heated and efficiency suffers, power keeps increasing but more fuel required at a higher rate. Saab use the turbo in some of their models to increase efficiency and emissions. This is a very rough rule of thumb and turbo sizes and pressure losses through intercoolers etc also come into play.

Also its sometimesnot the best idea to use lpg on an all alloy engine. Some do ok but some use the fuel as a cooling agent on the valves. Its a long story about
heat transfer through different alloy's, expansion rates etc. If anyone is on here that has used lpg for 50,000kms or more could they add comment on the durability of the 1uz-fe.

 

[XR8tt]

If the compressor working at it's peak or starts heating the the air at 6Lb !!
Then you are runing FAR too SMALL turbo/s..
A couple of IHI VF29's would go all the way to 18Lb..
With efficiancy at much lower rpm..
In any case READ the compressor maps of the turbo ...

 

[Merxus Benz]

Its the compression of the air itself that heats up not heatsoak from the turbo, its a physics thing.

Have looked briefly at the alternative fuels section lots of good info in there regarding lpg.

 

[XR8tt]

Its the compression of the air itself that heats up not heatsoak from the turbo, its a physics thing.

Have looked briefly at the alternative fuels section lots of good info in there regarding lpg.

Trust me if the compressor is out of it's efficiancy range it will heat the air.. There is very little heat soak when an engine is moving or running at cruising speed.. NO matter what fuel .. If it's the wrong sized component it won't work.. Here is a T04Z map for example..
If its outside the map it will either surge or be very efficient..
You can see here that 6 Lb is hardly in its peak.. In this case.. Ideal turbo for a 4.0 engine..
Twin 28's would be fine...Too many variables..