Need more towing power badly

[Range Rover Rogue]

Guys

I have owned my 1998 RR P38 4 litre for around 3 months now.
Absolutely wrapped with everything about it, especially the wonderful ride the EAS system provides.
My wife loves the sheer comfort & especially the lovely climate control.
I have LPG fitted (standard vacuum induction type) which seems to run better on gas then on petrol so fuel economy isn’t an issue.

But the problem I’m having is lack of power when I tow my camper trailer.
My off road camper trailer when fully loaded weighs in at around 900-1000kg when it’s all packed & loaded.
Cruising along at 100km on flat roads or Highways isn’t a problem but as soon as I encounter a semi steep hill of any sort this is where my issues begin.
There is just a massive lack of pulling power. Doesn’t matter if I’m on petrol or gas, it makes no difference.
I’m having to gear down to 2nd gear & keep the revs high just to get to the top.
The speed will drop down to 60km/h or lower depending on the steepness then the slow climb to the top begins.
Since I like to go camping with the family often, normally within the High country or alpine area’s I do encounter many hills.

I was expecting the V8 4 litre to have a bit more punch then this.
Have I made a mistake by getting a 4 litre & should i have purchased a 4.6 instead or a disco TD5?
Do all the 4 litre behave in the same manner when towing similar weight? I didn’t think 1000kg was that much really.
I really thought the P38 was going to be a superb towing vehicle so I’m slightly disappointed in this area.

Has anybody got any suggestions which may help me with this issue.
I was thinking maybe extractors or a smoother flowing exhaust system could assist, maybe.
Your input or suggestion would be really helpful.

thanks

[Scouse]

You can have the ECU chipped & some plenum mods done but there is no substitute for engine capacity.

Have you had the car checked out for any faults?
Or are you able to drive a similar car for comparism?

[PhilipA]

IMHO the problem isn't so much lack of torque but where it is developed.

The 4.0l makes maximum torque at something like 3K revs, while 100Kmh is about 2200 Revs.
Unless you anticipate hills and change back to 3rd or even second as you note then you will struggle to maintain speed.
The Thor manifold of 1999 addressed this by increasing torque lower in the band.
You have a GEMS system and gains from Piggyback chips are AFAIK pretty small.
I cannot help but think that there may be something wrong with your car eg badly carboned exhaust valves that maybe trigger knock sensors early, or a plug/lead breaking down and that it is missing on one or more cylinders which is sometimes hard to pick at speed in a V8.

My 3.9 Classic with Thor manifold, head mods and piggyback tows my 700 Kg loaded camper up hills easily. I climb Mt Ousley at Wollongong at the 80Kmh limit alternating between 3rd and unlocked 4th, and it is one of the steepest highway hills in Australia. A 38A is heavier but has a much better injection system.
A 4.6 with a Thor manifold would help a lot, but have an expert check out you engine. BTW do you have vapour injection or a "gas ring" as the gas ring will reduce mid/high end power considerably, particularly if the fitter has fitted a small one .
Regards Philip A
BTW check that the accelerator opens the throttle blade fully.

[bee utey]

If you have an Impco model 200 mixer fitted this is like a cork in the inlet. Remove it and try it on petrol without it fitted. If it is hugely better, then get a proper gas system, either 46mm bore mixer and european (complex) converter or injection.

[BusinessConnected]

Hello,
I regularly tow a 800kg Boat/Trailer combination and have very little problems with Downshifts ete on the Range Rover. This is both on a 4L & 4.6L. The 4L is straight Petrol at the moment and the 4.6L is Petrol/Sequential Injection Gas. The 4.6L is marginally better when using the Gas than the 4L, but I haven't noticed any huge differences.

I would be interested to see what would happen if you were able to take the LPG Injection out of your Air Flow route and see what happens running on just petrol. I'd also be inclined to try and run some SeaFoam or similar Upper Cylinder Head Cleaner through the Intake system as well.

[RR P38]

Get it Dynoed, that way you can see if it is making the power that it should.
And you can have a tune up as well.
I recently had mine on the dyno and picked up 6 kilowats and it is running really nice now.
Put some OEM plug leads on it i would say they are the original ones and now 12 years old.

[glenhendry]

adm333 recently found out the hard way that plugs (and maybe leads) for dual fuel engines are different to those for petrol only. I was surprised about this, but maybe it is something to look at?

Other than that, check the basics like vacuum leaks around inlet manifolds, air filter condition, maf sensor operation etc. Good luck.

[ytt105]

My 96 4.6 dual fuel is exactly the same when towing. I've had it to a trusted Rangie expert and he said it went great, not towing.

I think its true. you need to have the revs right up. Down change before the hill and floor it. It doesn't seem to matter how its driven the fuel consumption seems about the same.

If I can get an inlet hose I might try removing the gas ring and see if that helps.

Trev

[Range Rover Rogue]

Thanks for all the good advice & tips guys.
I'll certainly be taking them all on board.
I had better just add that just recently I had the heads off and reconditioned after a head gasket blew just after I brought my Rangie.
Afterwards the compression tests were all very good for an engine which has done 187,000km. All the plugs, leads and filters were replaced. It had the full service.
My mechanic who is a family member is pretty anal with the way he works.
Every vacuum hose was checked. He discovered 2 cracked vacuum hoses and a hidden split on the underside of the main air inlet hose. I thought i wasn't too bad with tinkering with cars but couldn't believe I missed these faulty hoses.
And I also had my radiator reconditioned as well just in case.
Besides a faulty idle stepper motor which he couldn't source because they are hard to come across the car was running superb.
When I'm not towing the car is fantastic. Runs a treat.
I'm starting to think that maybe it's the way I drive.

Thanks once again guys for all the input.

[Hoges]

it's not the way you drive... the 4L and the 4.6L are generally low compression models. With barely 200hp on the 4.6 and probably over 3tonnes all up with a camper trailer, the power/weight ratio is less than satisfactory for medium/steep grades, especially since the torque is only effective above 2500-2700 rpm...which is above the legal limit in top gear. I discovered that the long grades on the Pacific Hwy between BNE and SYD were best "attacked" in the 110kmh zone, at 115kmh where the drop in speed was only about 10kmh and we sailed over the hill in top gear. However on the same grade at 95kmh, I had to drop back to second gear and finally went over the top at 70kmh in third...

A mild turbo boost would be very useful in such circumstances:D...

A 5 or 6 sp auto would probably be a better bet.....the ratios are widely spaced on the standard 4sp ZF box

[Keithy P38]

Or a 6.5 litre Chev V8 diesel with TH700 or 4L80E would leave hills for dead - and return similar fuel consumption numbers.

Here's as much proof as I can give. A 450km round camping trip (including low range driving for 80km), figures based on GPS km's and bowser to first click:

My 2000 4.6 HSE - 15.4l/100km average
Dad's Defender with 6.5 V8 Chev diesel fully loaded (3 tonnes) - 13.6l/100km average

I know what i'll be doing if my motor decides to cark it!

Cheers
Keithy

[rangerdanger]

I tow a 1.3 tonne boat with my 1995 P38 on petrol with a free flow twin system exhaust and the vehicle is brilliant as far as stability and handling, but less than inspiring power wise. The engine starts to bog down at 2000-2200 RPM which unfortunately coincides with my preferred towing speed of 95kph. My solution is to either drop back to 3rd and drive at 90kph (revs up around 3000rpm. plenty of power in this rev range so you use a lot less right foot and it eliminates most of the exhaust drone) or to speed up to 110kph in top (not practical as speed limits and traffic rarely lets you on NQ roads)

My problem is also exacerbated by running 275 x 70 tyres which pushes the gearing up by about 10%. The higher gearing works in my favour when driving in third gear. I've considered a Tornado chip but by all accounts the gains are pretty marginal.
Unfortunately where I live the P38 is a rare breed (deep in Toyota country up here) so I have not had the luxury of driving a the high compression Thor motor for comparison.

Troy N

[Hoges]

Problem is, there were very few, if any, high compression Thor engined P38s imported here by LRA. AFAIK they are all LC variants with a CR of around 8.57:1 ... unless some of the late 2001/2002 models were the HC type. NAS models were HC.

[adm333]

If you have an Impco model 200 mixer fitted this is like a cork in the inlet. Remove it and try it on petrol without it fitted. If it is hugely better, then get a proper gas system, either 46mm bore mixer and european (complex) converter or injection.

Tell me more about this 46mm bore mixer. I don't know what I have, but if it could be better (without going injection) then I'm all ears ?

Is it a case of measuring the internal diameter of the mixer ring that is attached to the air intake ?

Dave

[bee utey]

The 46mm (bore) size mixer I use is made by AMR manufacturing, part number M352 but needs a light cut from its mounting end. It is 71.2mm dia and needs 72.2 to fit the GEMS intake. I know I posted a pic here once but dont know how to find the attatchment.

Found it!

http://www.aulro.com/afvb/attachments/technical-chatter/24293d1270604317-3-9-lpg-porting-polishing-compression-ratio-dsc02792.jpg

Mixer on left, lpg computer on right.

[bee utey]

And a pic of two different but suitable converters on my desk.

https://www.aulro.com/afvb/

[adm333]

Righto thanks, I suspect mine is already set up this way.

The mixer looks very similar and the air intake hose only just fits onto it ( I think there is a rubber spacer ring in between.

The converter on the right looks a lot like mine.

[bee utey]

Righto thanks, I suspect mine is already set up this way.

The mixer looks very similar and the air intake hose only just fits onto it ( I think there is a rubber spacer ring in between.

The converter on the right looks a lot like mine.

Do pop off the inlet hose and check as most of these are 40mm bore.

[big guy]

And a pic of two different but suitable converters on my desk.

http://www.aulro.com/afvb/attachments/technical-chatter/24292d1270604255-3-9-lpg-porting-polishing-compression-ratio-dsc02794.jpg

Thats a lot of space on your desk there, have you had a spring clean:p:p:p


On a serious note, I had the 3.5, 3.9, 4.0 and 4.6 some in low and some in high comp.
On gas get the right plugs, leads and timing plus listen to Bee utey.
My 4.6 on gas would tow a car trailer with car up any hill, in fact when my mate used it he was totally amazed.
The 4.0L would not be as good, and in low comp be a bit less still but in 3rd gear at 2800rpm I can not see a problem going up any hill with a 1.0t load.
thats from my experience.
Listen to him or better still come for a holiday to SA and get it to him.
Good luck

[Milton477]

Had a simmilar problem which turned out to be a worn camshaft. The lobes at the back of the engine were especially badly worn but did not cause a misfire. Have you tried the "RPi Engineering - Specialised Rover Engines" (http://www.v8engines.com/) website. Has some useful info on the longevity of the V8's & some practical ways of looking for wear.

[adm333]

Do pop off the inlet hose and check as most of these are 40mm bore.

I haven't taken off the ring yet, but I noticed it has "MOT 150" on it.

Also the ECU says AEB 295 on it and it is a sprint gas system.

Not sure if this gives any insight into what it is. I will take it apart and have a good look when I get it back to Brisbane.

Cheers
Dave

[bee utey]

I haven't taken off the ring yet, but I noticed it has "MOT 150" on it.

Also the ECU says AEB 295 on it and it is a sprint gas system.

Not sure if this gives any insight into what it is. I will take it apart and have a good look when I get it back to Brisbane.

Cheers
Dave
That will probably be one of the 38-40mm types. Unless your AEB computer has a manual adjustment on the mixture controller it may need to be upgraded too.

[adm333]

So what sort of cost would I be looking at to upgrade the system ?

[bee utey]

So what sort of cost would I be looking at to upgrade the system ?
Parts about $250, labour??? Depends on how much wiring needs to be changed for the different computer. I am not familiar with your computer, don't like what I've seen of AEB stuff. If you can follow instructions you could do it yourself from the written info with the comp.

[adm333]

I'm married ....... of course I can follow instructions :D

[bee utey]

I'm married ....... of course I can follow instructions :D
Great! I will be able to confirm some prices on Monday, pm me if you want me to follow this up.

[adm333]

Thanks I do want to follow this up, but it won't be for a few weeks.

When I get the car home I will get more details of what is there, take out and confirm the measurement of the ring etc.

The ECU says "self Learning ECU" which scares me a little

Anyway, I'm now excited about getting a little bit more grunt.

Cheers
Dave

[DANMAL]

Hey guys, I'm getting my 99 p38 motor rebuilt, is there an advise on getting better consumption or better torque, like maybe different camshaft? Any advise would be helpful... Thanks Sam

[big guy]

Hey guys, I'm getting my 99 p38 motor rebuilt, is there an advise on getting better consumption or better torque, like maybe different camshaft? Any advise would be helpful... Thanks Sam

Try by starting a new thread for starters!
Get a high compression motor, 4.6L min.
Some head work and a cam to suit what you are doing.
Perhaps different computer like Haltech or similar and it will be very ballsy.
Good luck.;)

[glenhendry]

Anyway, I'm now excited about getting a little bit more grunt.
Cheers
Dave

Keep us informed Dave, I too am interested in what kind of air throughput problem my gas injector ring is causing!

[adm333]

Hi Bee Utey

I had my air intake off today and took a pic.

Just to confirm, the opening measured about 40mm diameter.

Can you get bigger ones than this ?

[bee utey]

Hi Bee Utey

I had my air intake off today and took a pic.

Just to confirm, the opening measured about 40mm diameter.

Can you get bigger ones than this ?

Yes you can get bigger, 46mm, AMR Manufacturing make one suitable. The one I use requires a slight remachine and a notch filed in the side to clear the cruise control bracket.

However of more concern in your pic is what appears to be the gas inlet hose, with a brass elbow in it??? This may be the root cause of your problem, not allowing enough gas to flow for full power. There should be a smooth bend in the gas hose to connect directly to the inlet. A hose with a bend at one end is a standard lpg part, available from most wholesalers.

[adm333]

That elbow goes into the large rubber inlet pipe about 10cm before the actual plenum.

Is that the gas feed ?

[bee utey]

That elbow goes into the large rubber inlet pipe about 10cm before the actual plenum.

Is that the gas feed ?
Well I am not there to see closer, but if this hose comes from the gas converter then its probably the gas feed hose. Just I can't see any other hose big enough at the mixer. Oh, and your picture isn't all that clear so its a best guess.

[adm333]

I'll post a better picture with it all set up. That pipe doesn't go to the gas converter. It loops in to the main air intake pipe

[adm333]

Here's a better picture with everything in place.

The arrow shows where that brass elbow is connected.

Dave

[bee utey]

Much better pic, thank you. I think you can't just fit a bigger mixer as you have a Sprint LPG processor that has no manual power adjustment. So you can't easily adjust its flow rate. For that reason alone I will never buy a Sprint processor.

The one I use (Gastec) has built in tuning lights and manual power adjustment, so is extremely flexible. The most suitable version for towing is the FP50-TOW as it maintains full power continuously over a preset throttle setting. I retrofit this to D1's frequently and it has been a great success.