Hey Guys im looking at fitting a 4.6 short motor to my 93 RR. From people who have done this or have been involved How reliable are the 4.6 blocks.
I had 2 93 vintage blocks with liner trouble now and don't want to drop a heap of coin on a block that may have dramas down the track
im looking at a new 4.6 short eng from either LRA of a company here in perth.
How do the fuel and engine management system hold up to the change?
Is the cooling system big enough to support the increased eng size?
Anything i need to know?
thanks
Luke
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4.6 ltr reliabiltiy
Moderator: Micka
This is purley here say so dont take it as gospal.
The 4.6 has a tendancy to leak water throught the liners as it becomes porus.This water injestion is more prevalent is big block versions of the Rover block. Its hard to detect and syptoms are water usage, Very slowley at first and slowly increasing. The fault is supposed to be in the ECU. programming. The 4.6 tends to labour in higher gears trying to negociate hills, as aposed to the smaller blocks that change into a lower gear to go up a steep hill. simple fix is to change reprogramme the ecu.
All that said it wont matter if you are using diffrent ECUs.
Im lead to believe you can use 3.9 heads and ECU an a 4.6 block.
Graham Cooper Sydney does this a fair bit. ( I think thats right).
The 4.6 has a tendancy to leak water throught the liners as it becomes porus.This water injestion is more prevalent is big block versions of the Rover block. Its hard to detect and syptoms are water usage, Very slowley at first and slowly increasing. The fault is supposed to be in the ECU. programming. The 4.6 tends to labour in higher gears trying to negociate hills, as aposed to the smaller blocks that change into a lower gear to go up a steep hill. simple fix is to change reprogramme the ecu.
All that said it wont matter if you are using diffrent ECUs.
Im lead to believe you can use 3.9 heads and ECU an a 4.6 block.
Graham Cooper Sydney does this a fair bit. ( I think thats right).
For Kart racing information please visit our site at www.auskart.net
The new shorts tend to be pretty good, I think. I'm surprised you've had two 3.9s with dropped liners though, its not so common in them?
As far as the fuel system goes - 3.9 injectors and rail are the same as Lucas 4.6 ones, and a 3.9 computer will run a 4.6 decently. Obviously to get the best out of it you'd want a unichip or programmable computer *cough*Megasquirt*cough*, but you could happily run around on the 3.9 system. I ran on a flapper 3.5 setup with mine, and it went quite well, but the megasquirt makes it go so much better.
Your cooling system should be able to handle it - I'm running an 88 rangie radiator in mine, with 4 lights in front of it, and it stays cool most of the time (about 95 degrees). On warmer days if you are giving it a booting or under periods of load s it does tend to pop up just over 100 degrees, but as soon as you go down a hill the temp drops. I would say in yours it would run cooler, due to having the engine oil cooler. You won't have any major overheating issue anyhow, so you could run it for a little while and decide whether you want to upgrade your radiator. Personally I'm going to get a thicker core put in my radiator, for peace of mind.
If you are reusing your 3.9 sump make sure to bolt it on with two or three bolts before you seal it properly, and make sure the crank doesn't hit it at the front. If it does, bash the sump a bit until it clears.
If you have an early timing case you need a spacer for the crank bolt, but I imagine you have the crank driven oil pump type timing cover on yours.
can't think of a lot else at the moment, its a pretty straightforward conversion - all your 3.9 gear should bolt straight on. Any questions, feel free.
As far as the fuel system goes - 3.9 injectors and rail are the same as Lucas 4.6 ones, and a 3.9 computer will run a 4.6 decently. Obviously to get the best out of it you'd want a unichip or programmable computer *cough*Megasquirt*cough*, but you could happily run around on the 3.9 system. I ran on a flapper 3.5 setup with mine, and it went quite well, but the megasquirt makes it go so much better.
Your cooling system should be able to handle it - I'm running an 88 rangie radiator in mine, with 4 lights in front of it, and it stays cool most of the time (about 95 degrees). On warmer days if you are giving it a booting or under periods of load s it does tend to pop up just over 100 degrees, but as soon as you go down a hill the temp drops. I would say in yours it would run cooler, due to having the engine oil cooler. You won't have any major overheating issue anyhow, so you could run it for a little while and decide whether you want to upgrade your radiator. Personally I'm going to get a thicker core put in my radiator, for peace of mind.
If you are reusing your 3.9 sump make sure to bolt it on with two or three bolts before you seal it properly, and make sure the crank doesn't hit it at the front. If it does, bash the sump a bit until it clears.
If you have an early timing case you need a spacer for the crank bolt, but I imagine you have the crank driven oil pump type timing cover on yours.
can't think of a lot else at the moment, its a pretty straightforward conversion - all your 3.9 gear should bolt straight on. Any questions, feel free.
84 Rangie, 3 inch spring lift, 2 inch body, Megasquirted 4.6, R380, rear Maxi, 34x11.5 JT2s. Simex FM installed.
Thanks for the Info mate thats exactly what im after. I still have the cam/disturbutor driven oil pump on mine. Where does the spacer live behind the balancer on the crank? or behind the balancer bolt?
I had a 93 3.9 in my 86 for four years and flogged the shite out of it everyday of its life in the northwest of WA (see HOT...!!) and it started to use water. turns out number seven was leaking between the liner and block.
I just purchased the 93 RR and it was using coolant( aprox 1ltr per 2 hours of driving) i pressure tested it yesterday and after aprox an hour it hydraulicked on #3. Pulled the head today and there is visible wear and porosity in #3 liner. I suspect possibly a slightly bent rod has caused the wear.
I just want to be sure that properly driven and maintained the 4.6 is going to last.
Luke
I had a 93 3.9 in my 86 for four years and flogged the shite out of it everyday of its life in the northwest of WA (see HOT...!!) and it started to use water. turns out number seven was leaking between the liner and block.
I just purchased the 93 RR and it was using coolant( aprox 1ltr per 2 hours of driving) i pressure tested it yesterday and after aprox an hour it hydraulicked on #3. Pulled the head today and there is visible wear and porosity in #3 liner. I suspect possibly a slightly bent rod has caused the wear.
I just want to be sure that properly driven and maintained the 4.6 is going to last.
Luke
I guess if you dont flogg the shite out of it every day it may well last longer.Lucus wrote:Thanks for the Info mate thats exactly what im after. I still have the cam/disturbutor driven oil pump on mine. Where does the spacer live behind the balancer on the crank? or behind the balancer bolt?
I had a 93 3.9 in my 86 for four years and flogged the shite out of it everyday of its life in the northwest of WA (see HOT...!!) and it started to use water. turns out number seven was leaking between the liner and block.
I just purchased the 93 RR and it was using coolant( aprox 1ltr per 2 hours of driving) i pressure tested it yesterday and after aprox an hour it hydraulicked on #3. Pulled the head today and there is visible wear and porosity in #3 liner. I suspect possibly a slightly bent rod has caused the wear.
I just want to be sure that properly driven and maintained the 4.6 is going to last.
Luke
If your still live in a really hot area It may well be worth investing in a larger capasity radiator. I would also consider fitting Thermo fans. You can fit twin 14 inch on a Rangie radiator. I had twin 14s on mine never ever had a heating probs. I made an alluminum shroud to get the most effective cooling.
For Kart racing information please visit our site at www.auskart.net
the spacer lives between the head of the bolt and the balancer itself - this is due to the motors with crank driven oil pumps having a longer crankshaft.
Like any car, if you maintain it well, and its in good condition to start off with, you shouldn't have issues. I'm changing the oil every 5,000kms in mine, and doing the filter as well on every 10,000. I'm definitely getting the bigger radiator put in - I don't think it needs it that much, but it'll make me happier to know its there. I'm also considering flushing and refitting the little oil cooler a PO had fitted to mine, to help combat temperatures a little more, and preserve the oil a little (not to mention increased capacity of oil).
I have a mate who got a 4.6 with a dropped liner, and had that cylinder resleeved, and chucked it in - he has a big core radiator with twin thermos, and has had the motor in for about 3 years. Has done multiple offroad weekends with high rpm, and has toured around to the Outback Challenge and across through South Australia no worries.
Like any car, if you maintain it well, and its in good condition to start off with, you shouldn't have issues. I'm changing the oil every 5,000kms in mine, and doing the filter as well on every 10,000. I'm definitely getting the bigger radiator put in - I don't think it needs it that much, but it'll make me happier to know its there. I'm also considering flushing and refitting the little oil cooler a PO had fitted to mine, to help combat temperatures a little more, and preserve the oil a little (not to mention increased capacity of oil).
I have a mate who got a 4.6 with a dropped liner, and had that cylinder resleeved, and chucked it in - he has a big core radiator with twin thermos, and has had the motor in for about 3 years. Has done multiple offroad weekends with high rpm, and has toured around to the Outback Challenge and across through South Australia no worries.
84 Rangie, 3 inch spring lift, 2 inch body, Megasquirted 4.6, R380, rear Maxi, 34x11.5 JT2s. Simex FM installed.
The way to get around the whole slipped liner problem is to buy a second hand short motor with a slipped liner and have it sleeved with stepped liners.
There are people doing this in Oz now. The gasket fire ring sits on the step at the top so no water can get into the combustion chamber.
The step stops the liner moving. I understand they use a sealant when they are inserting it so no water leaks out even if the alloy behind the liner is cracked.
I would probably do this if I were upgrading to a 4.6
Regards Philip A
There are people doing this in Oz now. The gasket fire ring sits on the step at the top so no water can get into the combustion chamber.
The step stops the liner moving. I understand they use a sealant when they are inserting it so no water leaks out even if the alloy behind the liner is cracked.
I would probably do this if I were upgrading to a 4.6
Regards Philip A
Thanks for the info Phillip. There are several companies in Perth that are willing to replace liners in these motors. The latest 3.9 i've got hasn't actually had a liner shift issue it has spot wear that has become porous and is leaking.
Hopefully i get some decent K's out of the 4.6 and dont have any liner dramas but if i do im sure the method you have mentioned would sort it out
cheers
Luke
Hopefully i get some decent K's out of the 4.6 and dont have any liner dramas but if i do im sure the method you have mentioned would sort it out
cheers
Luke
Thanks again for all that amazing info Peter. I'l be sure to pick your brain if i run into any dramas....7.0 comp ratio...yuck. Im getting the heads serviced at the moment so i'l have to do some comp ratio calcs if the block i get is a low comp one and get the heads modded to suit. Are the comp ratios still marked on the block? 10 to 1 would be much nicer. How do the tin gaskets hold up in the 4.6's?
What are the differences in the 4.6 cams besides the cam retainer grove? are the journal still the same size?
cheers
Luke
What are the differences in the 4.6 cams besides the cam retainer grove? are the journal still the same size?
cheers
Luke
Geez, I do not keep tabs on all the permutations but I think its 9.35 :1, which means you have to use 95 or 98 PULP.
One solution if you want to use ULP would be to fit the 3.9 heads with a composite gasket and you will drop to about 8.4:1 or so.
My preferred solution would be to take the 35 thou from the 3.9 heads and then open the combustion chamber by unshrouding the inlet valve. You can easily get as many CC as you like ( and better performance). The difference between the 3.9 CC volume and 4.0-4.6 is about 6CC. If you took out say 3 or 4 CC you would get a CR of about 8.8:1 which is about the max for ULP.
If you used the 3.9 heads ( without shaving) with a composite gasket you would have to mill the rocker pedestals to recover lifter preload on the cam.
Re composite gaskets. There is not concensus on whether they are better or worse than tin.
My car is good but there are drool marks on the block from coolant, however it used only about 4MM from the radiator tank in the last year.
This could have been from a single incident of climbing a mountain range in 47C over the 2006 New year.
I was speaking to British and Swedish and they reckon the composites are sh1t. BUT be aware that you must have VERY good perfect? head surface and block surface for tin gaskets.
On balance I have read that it is poor engineering practice to have tin gaskets on an alloy block and head, and of course head gaskets are a major weakness of Rover V8s. So I will use composites again.
Regards Philip A
One solution if you want to use ULP would be to fit the 3.9 heads with a composite gasket and you will drop to about 8.4:1 or so.
My preferred solution would be to take the 35 thou from the 3.9 heads and then open the combustion chamber by unshrouding the inlet valve. You can easily get as many CC as you like ( and better performance). The difference between the 3.9 CC volume and 4.0-4.6 is about 6CC. If you took out say 3 or 4 CC you would get a CR of about 8.8:1 which is about the max for ULP.
If you used the 3.9 heads ( without shaving) with a composite gasket you would have to mill the rocker pedestals to recover lifter preload on the cam.
Re composite gaskets. There is not concensus on whether they are better or worse than tin.
My car is good but there are drool marks on the block from coolant, however it used only about 4MM from the radiator tank in the last year.
This could have been from a single incident of climbing a mountain range in 47C over the 2006 New year.
I was speaking to British and Swedish and they reckon the composites are sh1t. BUT be aware that you must have VERY good perfect? head surface and block surface for tin gaskets.
On balance I have read that it is poor engineering practice to have tin gaskets on an alloy block and head, and of course head gaskets are a major weakness of Rover V8s. So I will use composites again.
Regards Philip A
from my buggerising around with head shaves etc, I don't know that you'll be able to get much over 10:1 on a 4.6.... I shaved my heads (early 3.5 heads) by 110 thou (equivalent for 3.9 heads would be minus 35 thouish), to get around 9.3 comp, as the block I had access to was an 8.23 low comp (and I actually started with a 4 litre, then had to pull it out and swap my shaved heads etc over to the 4.6). I did lots of trial fits without gaskets to check that everything would clear when turning, and I'm fairly certain that even minus gaskets it cleared on the 4.0 after shaving.
When I went to bolt my heads onto the 4.6 as a trial fit, without gaskets, it would not turn, because it hit a valve. I had to sit it up by about 20 or 30 thou and fit my 60(? might have been a little more) thou rocker pedestal spacers before it would turn freely, which was fine as I'm using composite gaskets which I think were about 45 thou compressed. If you started with a high compression 4.6, the dish in the pistons is much smaller, and I don't know that I would have gotten away with it.
I'd say the most compression you'd get out of a highcomp bottom end 4.6 would be just under 10 - prove me wrong, but thats my gut feel from my build.
Oh yeah - and 110 thou requires a LOT taken of the intake manifold before it fits - had to take about 70 thou off each side I think, and even then you have to stand on it to fit it (squishs the composite gasket a little). Unless you can find someone who will do that cheap for you, be very wary, as I got ridiculous quotes to get it machined, as in more than it cost me to get my heads checked, machined and have the valves reset (and one valve and guide replaced).
Also, I don't believe the compression ratios are stamped on the block if its a genuine short motor. Not sure why.
When I went to bolt my heads onto the 4.6 as a trial fit, without gaskets, it would not turn, because it hit a valve. I had to sit it up by about 20 or 30 thou and fit my 60(? might have been a little more) thou rocker pedestal spacers before it would turn freely, which was fine as I'm using composite gaskets which I think were about 45 thou compressed. If you started with a high compression 4.6, the dish in the pistons is much smaller, and I don't know that I would have gotten away with it.
I'd say the most compression you'd get out of a highcomp bottom end 4.6 would be just under 10 - prove me wrong, but thats my gut feel from my build.
Oh yeah - and 110 thou requires a LOT taken of the intake manifold before it fits - had to take about 70 thou off each side I think, and even then you have to stand on it to fit it (squishs the composite gasket a little). Unless you can find someone who will do that cheap for you, be very wary, as I got ridiculous quotes to get it machined, as in more than it cost me to get my heads checked, machined and have the valves reset (and one valve and guide replaced).
Also, I don't believe the compression ratios are stamped on the block if its a genuine short motor. Not sure why.
84 Rangie, 3 inch spring lift, 2 inch body, Megasquirted 4.6, R380, rear Maxi, 34x11.5 JT2s. Simex FM installed.
Hours of fun! If you want about 9.2 - 9.3 on comp gaskets, my memory is pretty fresh on what i did/had to do, so just pm or post, I'll try and get more accurate figures.Hi Peter. Im a heavy duty diesel mechanic by trade so so the in's and out's of timing cams and deck heights, and liner protrusion are not new concepts to me but unfortunately i don't have alot of experience with on them a 4.6 litre!!
Once the block arrives i'l measure it up, measure up the heads and gaskets and work out exactly what comp ratio i'l have to start with. From there hopefully i can compare notes with other members to make sure my numbers add up
thanks again for all the info!
Luke
Once the block arrives i'l measure it up, measure up the heads and gaskets and work out exactly what comp ratio i'l have to start with. From there hopefully i can compare notes with other members to make sure my numbers add up
thanks again for all the info!
Luke
Lucas, Im glad your able to follow this because I got lost about 6 posts ago 
I guess these guys know there stuff, way to complicated for me.
good luck though and make sure there are pics to back this thread of the finished article.
I guess these guys know there stuff, way to complicated for me.
good luck though and make sure there are pics to back this thread of the finished article.
For Kart racing information please visit our site at www.auskart.net
Peter apologies if my post came across the wrong way..
I have plenty of experience building engines. Just not this eng!! and like you said its the little details that can cause you the major problems. I welcome any info no matter how trival it may seem because you never know when you might need it.!!
I about 600% more clued up about this whole process than i was this time last week and thats because of the great info you and Phillip and other have provided.
Please continue to explain anything you feel is relevant because im sure myself and others will benefit from you knowledge as well
thanks
Luke
I have plenty of experience building engines. Just not this eng!! and like you said its the little details that can cause you the major problems. I welcome any info no matter how trival it may seem because you never know when you might need it.!!
I about 600% more clued up about this whole process than i was this time last week and thats because of the great info you and Phillip and other have provided.
Please continue to explain anything you feel is relevant because im sure myself and others will benefit from you knowledge as well
thanks
Luke
Just found this table..Looks like some vey useful info!!!
http://www.rimmerbros.co.uk/discovery/i ... ssions.gif
http://www.rimmerbros.co.uk/discovery/i ... ssions.gif
Well i have the new motor sitting in the back off my ute...i went and saw the eng machinist today to try and work out the best way to get my compression back. I measure the dish in the old 3.9 pistons as 6mm and the new 4.6 as 7mm. The difference in piston height is .5mm for the 4.6 and 1mm for the 3.9
which gives me a total of 7mm for the 3.9 and 8mm for the 4.6 Plus the composite gasket thickness.
The eng builder is going to cc the heads to determine the exact volume and hopefully we can get away with machining the 35thou off as Rangin Rover suggested and this should see me with a decent compression ratio again....
Will have to wait and see i spose.....
Luke
which gives me a total of 7mm for the 3.9 and 8mm for the 4.6 Plus the composite gasket thickness.
The eng builder is going to cc the heads to determine the exact volume and hopefully we can get away with machining the 35thou off as Rangin Rover suggested and this should see me with a decent compression ratio again....
Will have to wait and see i spose.....
Luke
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