Engine Advice - Conflicts With Books - Any Experience ?

adarmo · Post by **adarmo** » Fri Jun 19, 2009 10:08 am

I am looking for the V8 for my sportscar.

I have read loads of sites and the latest Des Hammill book.

After reading I am left with the impression that anything other than a 3.5 or a tophat lined engine will be a disaster.

However I work with a couple of guys who have worked on Land / Range Rovers for over 20yrs and they say this is complete BS.

It has to be said that the books are put together from advice from specialists who make their money building engines and also presumably most of these are for competition hence the failures they see may be due to racing.

Certainly there are a lot of Land / Rangerovers with 130k plus on original engines.

Finally they say (bearing in mind they work on Range Rovers reather than sportcars) that the early 3.9's with the small journals are better and they have rarely had to fix them as opposed to 4.0 and 4.6 being more troublesome.

This seems to be the opposite of everything I've read so can anyone with EXPERIENCE of V8's post up their thoughts ?

Also did any factory RV8 have tophats as std ?

Thanks

kiwicar · Post by **kiwicar** » Fri Jun 19, 2009 1:13 pm

I have posted this up before, and I am sure I will be shot down again

but. . .
3.5 very rearly drops liners
3.9 also relativly rearly drops liners
4.0 2nd grade big journal blocks, drop liners quire often
4.6 top grade big journal blocks, drop liners the most
I believe the small journal crank causes less frex in the block around the base of the liner as it is less stiff so causes fewer cracks in the block in this region, further the bigger journal weakens this area of the block further relative to the stiffer skirt of the engine on these blocks (resulting from the cross bolting tieing the bottom of the engine much better)
Part of the reason I think this is that the TVR 4.5 and 5 litre engines are small journal non cross bolted and seem to suffer less from this issue.
Yes alot of advise is based on what the party concerned has to sell and if you read what is commonly written you would believe the RV8 was ready to drop a liner at any moment, they are not as bad as they are portrayed. Top hat liners work but remember it is effectivly converting the engine to wet liner which to me is not the answer to a problem of badly designed load paths. Redesigned aftermarket blocks are nice but if you have the money for one of those spend it on an chevy LS* engine and have something modern that will produce real power for heaps less money
Here we go again

Mike

adarmo · Post by **adarmo** » Fri Jun 19, 2009 1:44 pm

That is pretty much what they were saying.

Thanks

kiwicar · Post by **kiwicar** » Fri Jun 19, 2009 3:05 pm

What car is it going in? just there are many other V8s to choose from, the rover is good and cheep if you already have one that is running and only want 190 to 210 BHP, if you are starting from scratch then there are many more interesting options that will be cheeper in the long run, and alot less worry. Chevy LS 1,6,7 etc, Northstar (lexus, but not a popular choice) if you want alloy. Chevy LsX, 2 and a few others if you want bomb proof light weight iron blocks likwise 302, 351 windsor ford. Small block chevy for big power on a very low budget, then all the big block engines.
If you go for a rover then say you want more than 220 bhp then there is a cheeper more reliable alternative.*
Mike

* unless your called Ian Stewart

adarmo · Post by **adarmo** » Fri Jun 19, 2009 3:12 pm

An MX5 its currently running around 210bhp with a supercharged 1.8 so my target was around 240bhp and similar torque.

But it has to be lightweight and the LS series seem to be a bit too much in demand and have more power than I want.

I agree the Lexus is a good contender but I didn't want the hassle / cost of a manual conversion plus the extra wiring.

However if the books are to be believed about the Rover reliability then I may well go for a Lexus.

Except that the parts are very expensive and most have got 120k+ on them now and will have had quite gentle lives which I know can then lead to blow ups when you start revving them.

I'm unaware of any other smallish, light, cheapish V8 options.

topcatcustom · Post by **topcatcustom** » Fri Jun 19, 2009 3:49 pm

Whilst there are lots of tales about how poor the RV8 is, dont forget there are hundreds of thousands that have been and still are being used without any problems! If the reputation was really that bad nobody would bother with them and they wouldn't have been produced for 45 years!

Anyway, I have to say that as I am using one too- and in an mx5!

TC

adarmo · Post by **adarmo** » Fri Jun 19, 2009 4:13 pm

I know, which isn't the impression you get from books / specialists.

I know that too...

I've already read your threads and studied your diff location pics.

Just been re reading up on fitting a manual box to a Lexus V8, £1300 plus the supra box !

sidecar · Post by **sidecar** » Fri Jun 19, 2009 4:57 pm

I spent A LOT of time looking into this before I bought my 4.6 block. It was a brand new Power Train Products short engine, red grade block that had been sat under someones bench for 10 years.

In my humble if you can get a red grade block that you know has never been over heated or suffered a rad hose blow out then you should be OK. (How you know this is beyond me!)

The other thing is don't run any of the RV8 lumps hot regardless of its size. I run mine at 75-80. It never goes above 83.

Running the lump cool could be tricky with EFI.

As to getting 240 BHP out of it, well it will need to be biggish and tuned on top of that. My lump has V8 Developments Stage III heads, a piper 285 cam, eddy manifold and an eddy 500 or 600 carb (depending on my mood!) the CR is 10:1, and the ignition has been reworked.

My lump makes 280 BHP and 300 ftlbs of torque. The real kick is that it makes over 280 ftlbs from 2.5K rpm. Its in a Cob replica and will spin the wheel wildly in second gear. (I don't go out in the wet ever!

)

Pete

RoverP6B · Post by **RoverP6B** » Fri Jun 19, 2009 11:38 pm

A 3.5 litre powered by 1974 Rover 3500 for 33 years and 203,000 miles.

The only major mechanical repair on the engine in all that time was replacement of head gaskets, due to one leaking after 21 years and new rocker shafts.

The main bearing caps did work loose after 14 years and they had to be re-torqued. Upon removal, all were once again below minimum torque specification. There was evidence of fretting but as far as I could see, no bolt holes were cracked.

I agree with Pete on the importance of running the engine in the 75 to 80 degree band.

My 4.6 is fitted with top hats and I use a 74 degree thermostat. The engine has just on 20,000 miles up now and has worked flawlessly.

Regular oil changes are important I feel, changing oil and filter at least every 3000 miles. I have seen engines where this has not been followed, and they look and sound very shabby in a much shorter space of time, although having said that, the V8 is extremely tough and will continue to run pretty well indefinitely regardless of how it is treated.

I was discussing engines with my Rover V8 engine builder, he said that he had seen a few broken 3.5 litre crankshafts over the years, but never a 4.6 crankshaft. The engines with the broken crankshafts were still running, just making "one hell of a noise" as he put it.

Ron.

kiwicar · Post by **kiwicar** » Sat Jun 20, 2009 7:41 am

a rebuilt 3.9 with new standard pistons and stage 1 heads abd a mild cam that does not need too much setting up can be done for about 800 to £1000 pounds. by you have the right front cover provided you use the standard injection and ignition. it will give you about 210 BHP.
want more? a set of stage 3 heads are about another £600, £500 for a webber carb, and another 250 for machining for better valve springs and machining. will get you another 20 to 30 BHP so 240 BHP is about £2400 if you are lucky, and do all the assembly yourself .
more still £500 rods £270 plus £50 of machining convert to roller cam £600 aftermarket heads (if you can get them £1400)
an LS 5.5 engine can be got off ebay for about £1800 plus getting it in the country (£500) get you about 240 un modded the LS just makes more sense to me
Mike

ppyvabw · Post by **ppyvabw** » Sat Jun 20, 2009 2:43 pm

kiwicar wrote:I have posted this up before, and I am sure I will be shot down again but. . .
3.5 very rearly drops liners
3.9 also relativly rearly drops liners
4.0 2nd grade big journal blocks, drop liners quire often
4.6 top grade big journal blocks, drop liners the most
I believe the small journal crank causes less frex in the block around the base of the liner as it is less stiff so causes fewer cracks in the block in this region, further the bigger journal weakens this area of the block further relative to the stiffer skirt of the engine on these blocks (resulting from the cross bolting tieing the bottom of the engine much better)
Mike

I think the 4L are much worse than the 4.6 aren't they, as they use lower grade blocks? Could be wrong on that, it's what I have read and not from experience.

I think it was your advice about the small journal crank that made me decide I wanted a small journal 3.9 cross bolt block rather than a large journal 4 or 4.6. Cheers!

spend · Post by **spend** » Sat Jun 20, 2009 5:01 pm

kiwicar wrote:I believe the small journal crank causes less frex in the block around the base of the liner as it is less stiff so causes fewer cracks in the block in this region, further the bigger journal weakens this area of the block further relative to the stiffer skirt of the engine on these blocks (resulting from the cross bolting tieing the bottom of the engine much better)

I certainly prefer the smaller cranks based on observation of experiences, weakening the block by removing material does seem like a foot shot to me..

kiwicar wrote:Part of the reason I think this is that the TVR 4.5 and 5 litre engines are small journal non cross bolted and seem to suffer less from this issue.

Sorry but I don't think that is correct. All the Chimaera 450s (well 4.6 really - its just TVR nomenclature) are fat cranks, and only very early 500 pre-serps have skinny cranks (maybe <1% of TVR 500's?). The pretty rare 444?cc pre-serp 450's are outside the scope of this thread, although they were skinny cranks they were only used in a few Wedges and a couple of Griffiths apart from the Tuscan racers AFIK.

I certainly know of plenty TVR's 4.0/4.5(6)/5.0 that have suffered the dreaded problems, but can't recall any being pre-serps with the svelte crank and meat left in the block

topcatcustom · Post by **topcatcustom** » Sat Jun 20, 2009 5:07 pm

I still cant help thinking the reason for so many liners slipping in 4.0/4.6 engines is simply that they are newer and thus had to produce less emissions than the older engines, the easiest way to reduce the emissions was to run the engine hotter- which makes the ally block expand more then the iron liners etc etc.

But just my opinion! I have a 4.0 and will be running a 74deg stat so will see if I have any problems!!

ppyvabw · Post by **ppyvabw** » Sat Jun 20, 2009 6:01 pm

topcatproduction wrote:I still cant help thinking the reason for so many liners slipping in 4.0/4.6 engines is simply that they are newer and thus had to produce less emissions than the older engines, the easiest way to reduce the emissions was to run the engine hotter

Yes I think that is one of the proposed reasons too.

I also tend to think that later type stretch bolts didn't help because from what I have read of where the blocks crack, it tends to be a circumferential line at about the same place as the threads for the head bolts. Could be totally wrong there.

Richard P6 · Post by **Richard P6** » Sat Jun 20, 2009 6:32 pm

ppyvabw wrote:I think the 4L are much worse than the 4.6 aren't they, as they use lower grade blocks? Could be wrong on that, it's what I have read and not from experience.

In thought it was the same block? Just a longer throw crank.