Is LPG OK for 1UZ?

[kpwemu]

Hi, I've read several threads on this site about using LPG on a 1 UZ but I still haven't found a simple answer to my dilemma. Nearly everyone who wants to use LPG seems to be looking to squeeze every bit of horsepower they can find eg turbos, blowers, various types of injection systems. I am not looking for mega horsepower, simply cheap (PULP prices are outrageous and it will only get worse) smooth, reliable power that the 1UZ delivers in standard form. My Zephyr ute has a 302 Windsor in place which is running on straight LPG. I am converting the ute to a 1UZ and it makes sense to retain the gas system considering the price of PULP. It is an IMPCO system which powers a 5 litre V8 just fine. I also have a 3.8 litre Commodore V6 in a Mk1 Cortina running on straight LPG and it runs just fine. No changes to computer, sensors or anything else. Simply delete petrol, add LPG. This is what I'm hoping to do to the Zephyr once the 1UZ is installed.
Q1, Would the mixer be OK with a 4 litre 1UZ or need upgrading (OK with 5 litre Windsor)?
Q2, Will a 1UZ run OK on straight LPG ( minor changes in horsepower is not an issue. I'm not after performance, simply pleasure cruising)?

In summary, if simple driving pleasures are all that is required, can I simply delete petrol, add LPG to the 1UZ?
Regards, KPWEMU

 

[cribbj]

If your current vaporiser and mixer are supporting a 5.0 liter V8, they would do fine on the 4.0 liter 1UZ, HOWEVER, the 1UZ is an SFI engine, where your Ford Windsor probably came carbureted. You may want to investigate fitting an SFI LPG system on it, as you may find it difficult adapting the existing Impco mixer(s).

There's a fairly active Yahoo group for people interested in LPG systems for cars. http://autos.groups.yahoo.com/group/lp-gas/

John

 

[kpwemu]

Hi John, Thanks for the info. Accepting that I will need to change some of the hardware of the LPG system, can I assume that the engine will run normally with no other changes once the gas system is set up? Kevin

 

[cribbj]

People from that Yahoo group seem to be having good luck with the latest generation of multipoint injection systems. They've also found that the engines like more timing than with liquid fuel, and are actually running as well or better than with liquid fuel, which goes against conventional wisdom which says the engine should lose about 5-10% power on LPG.

Best,

John

 

[kpwemu]

Thanks John. Sounds promising. I must do some more research. Kevin

 

[Pro]

don't they lose power because the timing is still set at 95 RON settings?

i mean, LPG has like 102 or 106 RON or something, so advancing the timing should not only see you equal your previous power, but you should surpass your previous power levels and have a cleaner engine to boot.

i love LPG installs.

all the best.

 

[hi-lex]

Do 1uz have any probs with cracking heads on lpg? I ask as it is well known prob on hilux 3rz-fe motors, these are bullet proof and can handle lots of boost stock just like 1uz when turboed, but on gas they crack between valve seats, seeing they are 4valve per cyl like 1uz and are simular era I thought I would ask if anyone has had probs

 

[cribbj]

Is the problem with the 3RZ possibly seat recession, then the heads are cracking? Anyone done an autopsy on a failed head to figure out what caused it to crack?

Valve seat recession is a problem with LPG on some heads that weren't designed for unleaded gas, but the 3RZ-FE motor is a contemporary motor and it shouldn't have that problem.

John

 

[cribbj]

don't they lose power because the timing is still set at 95 RON settings?

That in itself doesn't cause the power loss, but it certainly doesn't take advantage of the LPG's higher octane rating.

What caused the power loss in a conventional, NA setup was two things - first, the "old" style (Impco) LPG systems used a venturi style mixer to draw the LPG into the engine. The mixer operated at a higher deltaP than a conventional carburetor, so there were more inlet losses, and therefore more power lost than with liquid fuel. Second, more gas (by volume) was being drawn into the engine and was displacing more air than the liquid fuel was, hence additional power losses.

The cool thing about FI and multipoint LPG injection is that these two disadvantages nearly disappear, plus the timing can now be advanced to take advantage of gas' higher octane.

EGT's need to be monitored closer because there's no "natural" phase change cooling with gas like there is when liquid fuel is injected, vaporises and cools the valves and chambers. This one disadvantage can easily be offset by MW injection, however.

People in the UK have been switching to LPG for economy, but it's only been in the last six months that they've discovered the engines like more timing now, and once they're properly set up, many of these converts are reporting the same or slightly more power (with dyno graphs to prove it).

John

 

[deankdx]

i have just contacted Peter at Gas research in Dandenong Victoria, sent a couple of photos regarding my intention to use the S-400 gas research carb and mixer i allready have and adapt it to the lexus motor in my Falcon, he at least had heard of the 1UZ and says that the toyota TPS can be a pain, he may have to send it away to be modified(i dont know what the process involves)

the process for install and tune is expected to take more than a day @$70 hour which still sounds reasonable considering the benifits and savings once its set up. and will run duel fuel in my case, without altering the tune for ignition. i expect it will be fine. i'll let you know what the reply is, when he gets back to me.
LPG for me either way, but the system currently fitted by the previous owner is restrictive and robs power due to a 40mm restiction in the inlet. economy was exellent and this car has been running LPG for 12 months without hassles with the previous owner

 

[Deuce]

Hi Deankdx. On a trip to Melb. back in 2001 I took the complete upper half of my 1UZ-FE intake manifold to GRA. They recorded all the measurements off the intake/throttle body flange and made up a 90 degree bend to mount the S440 gas carby parallel with the engine.The TPS was not a problem and bolts straight onto the carby.( They said it appears to be the same as the 80 series landcruiser.) Perhaps your gas carby needs to be modified to fit the TPS onto the shaft. They also supplied a GRA modified B2 Converter and everything else to complete the system. This is a long term project going into a streetrod and is not up and running yet. As this motor will eventually be supercharged I would prefer to use gas injection to reduce the risk of backfire and damage to the blower, but as yet there doesn't appear to be anything on the market. Let's know if you find something.

 

[deankdx]

Hi Deankdx. On a trip to Melb. back in 2001 I took the complete upper half of my 1UZ-FE intake manifold to GRA. They recorded all the measurements off the intake/throttle body flange and made up a 90 degree bend to mount the S440 gas carby parallel with the engine.The TPS was not a problem and bolts straight onto the carby.( They said it appears to be the same as the 80 series landcruiser.) Perhaps your gas carby needs to be modified to fit the TPS onto the shaft. They also supplied a GRA modified B2 Converter and everything else to complete the system. . Let's know if you find something.

thats very encouraging thanks Deuce,
was you're thottle body from a crown motor? with the 2 sensors(or whatever they are) at the front? pic below is mine. if this is the same what do you do with all the electrical plugs? are they needed? i'm keeping std ECU due to auto At the moment.

 

[kpwemu]

Sorry guys but I'm a real novice when it comes to the serious technical stuff. What is "TPS"? Kevin

 

[deankdx]

Sorry guys but I'm a real novice when it comes to the serious technical stuff. What is "TPS"? Kevin

hi Kevin TPS is the throttle position sensor, works out things for timing and gearshifts etc, have a look at my photo, i dont even know what does what on that throttle body.
PS hows that cortina V6 progressing?

 

[kpwemu]

Hi Dean, Major setback with the Cortina which of course has put back the 1UZ into the Zephyr by a few months. After taking it out for its maiden voyage it was found that both my axles were bent???? We're talking about a Ford 9 inch diff that has only had a 4 cylinder motor. It appears whoever narrowed the diff and converted it to the Holden stud pattern butchered the whole thing. Even the diff housing is bent. Just disgraceful workmanship I'm told. Bottom line; 2 custom made 31 spline billet axles, bearings etc, side gears on diff centre change to accept 31 spline and diff housing had to be straightened = megadollars. Hopeful of mid year completion. In the meantime I'm doing more research on the 1UZ. Gary at Hoppers Stoppers told me he has seen your Falcon and had a few ideas in mind for my zephyr as a result. Would there be any chance of me having a look at some stage? I've actually never seen a 1UZ in the flesh. You can email me direct at [email protected] Regards, Kevin

 

[Deuce]

Hi Deankdx. My 1UZ-FE is from an Ls400 or Celsior,but the intake is the same as yours.The dual throttle body (DTB) can be removed and replaced with the GRA carby.An adapter is req'd to bolt to the manifold. The plugs and wiring in your photo are the main TPS and the sub-TPS.The sub-TPS (closest the AFM) can be removed (keep as a spare), as it is used by the Traction control computer and not req'd.The main TPS bolts onto the GRA carby.The DTB is water heated and these hoses need to be blanked off. Retain the AFM as before. The above should allow running on dual fuel with the gas carby acting as a throttle body on petrol. By going straight gas the following can be removed: fuel rails, injectors and wiring; cold start injector (under upper intake manifold) and wiring; ISC valve (on front of manifold),water hoses and wiring; complete emission system except PCV valve and hoses. The following will remain: wiring to ignitors,cam sensors,crank sensor,oil press and level sensors, water temp sensors,TPS, all earths.The factory ecu should still control the ignition an auto trans and everything is so much simpler.Hope this helps.

 

[deankdx]

Hi Deankdx. My 1UZ-FE is from an Ls400 or Celsior,but the intake is the same as yours.Hope this helps.

thanks Deuce, that info helps heaps, hopefully Peter from GRA will confirm agree as it will be difinatley going gas research duel fuel if so.

kevin i may get to Sunbury either this sunday or two weeks from now(will be early morning 8.30- 9ish on sunday), a work mate lives near the holden dealer and wants me to visit one day soon. i'll send you an email.
thanks Dean

 

[kpwemu]

Hi Guys, This is exactly the type of info I have been looking for. Someone who's been there done that. Can you tell me more about GRA, the type of work they do, costs etc. Keep in mind that all I want is a STRAIGHT LPG system that will give smooth reliable motoring. I don't thrash my cars, burnouts, drag racing and all that stuff so performance is not top priority. Maybe a few basic mods like headers, exhaust, specialised tuning etc. I've spent a fortune on cars and can't afford to constantly tipping in megadollars. I currently have 2 half finished cars, both costing heaps and a lot more to go. With this in mind, the type of things you are telling me is perfect. This is basically the plan. I want to be in the position to take the Zephyr to Hoppers Stoppers, get a half cut and say go for it. They can convert anything, but I don't think they have done a 1UZ before. Rather than pay them "dollars per hour" while they work it out, I will be able to print out and hand them the info from the guys on the Lexus Forum and say send me the bill. Apart from fitting it all in the Zephyr, I want straight gas and maybe power steering and air con. Sounds simple doesn't it. Kevin

 

[Deuce]

Kevin. One other item I failed to mention that could be removed if using straight gas are the Exhaust Gas Oxygen (EGO) sensors.Personally I would retain them and connect them to EGO gauges to monitor the air/fuel ratio. Jaycar sell an EGO kit which is easily set for LPG. Most EGO gauges are for petrol only. John.

 

[hi-lex]

Try this link, gas injection, not the old hat gas carb junk, looks very interesting
http://www.gas-injection.com/lpg-gas-injection-technologies.html