Top hat liners advise

[ianstaffordshire]

Hello looking for a bit of guidance here, today I stripped down the 4.6 gems engine I brought to rebuild and fit in my tvr wedge eventually I was intending on fitting top hat liners as I read they can slip the old ones however now it's in bits it doesn't have liners fitted so is there any benefit from fitting them I intend to up the compression to 10.5 to 11:1 and fit a fast road cam it already is running canems ignition with slightly larger injectors.
What hp should it realise anything over 250 would be nice.

[Wedg1e]

You sure it doesn't have liners? You wouldn't expect to run the pistons directly in the alloy block.

I imagine 250bhp should be a breeze with a 4.6, you can get 240-250 from a 3.9/4.0 (mine was dyno'd at 256).

You'll need better brakes than standard too

[BlueWedgy]

Not the engine you are looking at, however couple of US guys trying to get more power out of SD1 V8.
This is the second part of the engine rebuild, I would guess more to come. This may give you some ideas?...

https://www.youtube.com/watch?v=EwXQcWtUfHg

[ianstaffordshire]

There are liners extremely thin ones with no discernable ring at the top .
Interesting video that have decided to get it balanced as well if it isn't too expensive.
And I have a set of princess brakes to go on at some point.

[Wedg1e]

As far as I know the liners were cast-in (i.e. the alloy was poured around the iron liners) rather than pressed-in. One of our clients at work used to be West Yorkshire Foundries where the blocks were cast and machined along with the 6.75L Rolls V8 (now that is a large block!) - seem to recall being told the RV8 blocks were sand-cast rather than die-cast.
Between the block and the heads there is a hell of a lot more aluminium used than in modern engines which have been CADCAM'ed to within a micron, that's why the RV8 can tolerate massive heat cycling. I don;t know how yo;d have to abise one to shift a liner.

I fitted Princess calipers to my car, never been sure it made that much difference. They're about the same weight, the pad area is smaller and overhangs the discs so there must be some losses there - granted the 4 pots might apply more force but no use if the brakes are cooking and fade. The 390 already had vented discs but you're still stuck with the disc diameter unless you go for bigger wheels, and discs... and modern calipers.
I did once measure a modern Landrover caliper of some flavour and it looked like it might fit the mounting holes with about the right offset, but never took it any further.

[ianstaffordshire]

[tr7v8]

Wedg1e said:

I fitted Princess calipers to my car, never been sure it made that much difference. They're about the same weight, the pad area is smaller and overhangs the discs so there must be some losses there - granted the 4 pots might apply more force but no use if the brakes are cooking and fade. The 390 already had vented discs but you're still stuck with the disc diameter unless you go for bigger wheels, and discs... and modern calipers.
I did once measure a modern Landrover caliper of some flavour and it looked like it might fit the mounting holes with about the right offset, but never took it any further.

I had Princess 4 pots on my TR7 V8. They were not great. However when I changed to an uprated master cylinder they were hugely better. I believe the master was a Sherpa one. Personally I think there are better callipers around these days for a conversion. I would probably be looking at Porsche Cayenne callipers, which are 4 or 6 pot, and alloy. The Princess callipers are cast iron and weigh loads.

[ianstaffordshire]

Taken the plunge and purchased top hat liners and 4.0 hc pistons today also started flowing the heads not going crazy with the heads just a little off to help with flow.
Has anyone tried the valves with a slimmer stem where it passes through the exhaust or was it the intake side can't remember.

[SEvans]

I run a 4.6 Thor RR and just replaced the engine.... There are definietly liners in there. The issue is the block cracks behind the liner and releases the liner. There are quite a few theories/reasons why this happens. One is that the machine tooling got a bit 'sloppy' and the position of the bores moved somewhat meaning a thin block wall in places. Another is overheating issues and another is running leaner mixture to meet emmission laws.It's probably all three or a combination of them.
The top hat liner doesn't stop the block cracking but it has a seal on the bottom and the top hat which traps the water (if the block does crack) behind the liner. Problem is the symptoms can be subtle. Sometimes a small ticking noise as the liner moves up and down. A small use of coolant and it's not clear where it's going. You can sometimes tell if the top of the piston is 'steam cleaned' due to the water... but equally this could be a blown head gasket.
Turner Engineering have a good reputation for supplying top hat engines. From what I looked at it's not going to be cheap to get a top hat liner engine built. I ended up buying a second hand engine for £500 and taking a chance. I couldn't justify 4-5K on a top hat liner engine.
I know nothing about Rover V8 engine upgrades but I would have thought any upgrade would increase the stress on the engine and therefore more risk of failure.
I run Princess calipers and AP bells & rota's on mine and they seem quite good. Many fitted the Granada disks with the Princess calipers and this is when you get the pad overhang. The AP rota's do fit in a 15" wheel but they are hard to find these days.

Started writing this before your last post.... so you bought a Top hat engine... probably a good move if you are looking for more power.

Cheers Steve

Edited by SEvans on Wednesday 15th October 18:34

[ianstaffordshire]

I have brought the liners and pistons going to get them machined locally had a price of £1000 to fit and face the block that seems about the going rate.

[BlueWedgy]

Just a thought. I am no engine builder, but Barum engines are one of my watches. They normally like to get the pistons and liners so as they are sure that the tolerances stack-up correctly for fit |(machining/ honing).
Be clear with the machining guys on your expectations on "engine use" so as they gap the rings correctly.
As part of the balancing, they often thin down the crank web into a more chisel like profile rather than blunt, to try and help reduce churning the oil during rotation.

Interested to see how this turns out, keep the posts coming.

Edited by BlueWedgy on Thursday 16th October 13:50

[ianstaffordshire]

Done some mild porting today taken the rough out of the intake and exhaust ports trying to match to the gaskets and flowed around the valves as well as I can.
Every little helps I guess going to get some sandpaper rolls for the die grinder and finesse them all a little then off to have the seats and deck re-cut going to replace the original valves with OEM ones with some uprated springs.

[KelWedge]

4.6 you need better brakes, decent engine management helps, 250 bhp not a problem, I have enlarged plenum and light flywheel, emerald engine management, some prefer megathingy , also dont forget handling so Gaz Gold or something like that and decent tyres, tyre spin on cold tyres in third not nice.

[ianstaffordshire]

I have gone for canems ignition and fueling larger twin spray pattern injectors pipercross air filter heads will be mildly ported
a fast road cam high compression pistons 10.5:1 minimum compression with top hat liners.
The chassis already has spax shocks fitted and I will be upgrading the brakes got to get the wheels refurbished so will probably put new tyres on as well.

[AndyASC]

First up, you will need to find an engineer who knows their stuff. I went to Richard Ward at Ward’s Engineering. I asked him to inspect my 4.6 block, crank, pistons etc etc. He then fitted top hat liners a must for any 4.6 engine. I then rebuilt the engine before dropping into my car. There are a number of things you have to be aware of far better to chat about it than me typing out everything on here…

[ianstaffordshire]

Can't email you my number for some reason
[e-mail] thanks