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10.5:1 and Composite or 9.35:1 and Tin - or 10.5:1 Megasquirt Tin ?


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I have a 110 V8 Stage 2 with a low compression engine with 80,000 miles on it. When I  bought it it ran like a dog. It hadn't been serviced and was full of black sludge.

The garage gave it a "refesh" to try to breath life into it of a new cam and timing chain kit, reground the valves  and ran a few gallons of Gunk through it to clean out as much sludge as possible. It ran better but I still hate it ... I also suspect they may have put composite head gaskets in .. 

With lockdown I have some time on my hands and have decided to do a full rebuild. 

I have a set of 10.5:1 pistons and a set of 9.35:1 as well. Have read through a ton of stuff could the panel help clarify if 10.5:1 pistons and composite gaskets would get me the best results or do I go for 9.35:1 and tin ?!

The cam is a 3.9efi as this seemed to be a cheap upgrade and will stay ... heads are original low compression 1986 ....

If I go Megasquirt could I go 10.5:1 and tin and use the granularity of ignition control and Shell VMax to avoid detonation ?!  I didn't buy the thing for economy and only used a tank of fuel last year !

Thanks in advance ..

 

 

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First thing to do will be to compression test it. If you have unequal compression pressures, it will never run properly.

I guess its a 3.5 as you say you have 10.5 pistons ? Assume it already has EFI or is it on carbs ?

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Engine has 8.13:1 pistons at the moment and I can swap them for either the 9.35:1 or the 10.5:1 pistons ... compression was ok after the rebuild but I can have another go.  

Its currently on a single Weber carb .. so I think I'll just do the piston swap first and get it running hopefully with a bit more power before then going to the next step of efi ... the addition of more ethanol in fuel is guiding me to the 9.35:1 and I'll stick with tin for the first go and see if I get the improvement I need .. I also figure my 8:13:1 distributor may cope with a 9.35:1 swap but not much more ..

I was however gently wondering if Megasquirt would allow a higher compression ratio as you'd scrap the distributor, get a much more granular advance curve that could be tailored and better control of fuel but didn't know if 10.5:1 was pushing my luck ? 

 

Edited by Chris Gale
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Do you mean  the four barrel Weber and manifold, or a two barrel 38DGAS conversion that they used to do by modifying the standard SU manifold ?

3.9 camshaft is not great for carburettor engines.

10.5 pistons were only fitted to early engines, and will not take much more than 5500 rpm. Lots of modern engine run that high though.

Cant comment on Megasquirt as I have no experience of it personally, but from what I read on here, it can be very problematic unless you are a tech genius.

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I am not sure what your thinking is re the dizzy cannot handle higher compression ratios - doesn't matter but with higher compression ratios, a better more power full coil may be more appropriate.

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Dizzy, best thing I ever did was get rid and use MegaJolt but I guessed that mine was worn out which proved to be true.

3.9 cam not good for carbs?? This was a de facto upgrade before stump puller etc cams AFAIK.

Megasquirt, a lot more work than MegaJolt but if you intend to go injection later then worth it if not MJ is much simpler/cheaper.

 

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When lockdown/Covid is over if you want to pop round and talk megasquirt etc. I'm round the corner from you and have a couple of Megasquirted trucks you can poke about / have a go in.

Unless you're very attached to the original engine number I'd usually say just pulling a larger lump from a crusty P38 and dropping it in is about the easiest cheapest power/torque increase you're going to get.

The last time someone on here asked about composite gaskets it sparked a 20-page holy war :ph34r: having run them myself on a 3.9 I (still) really don't believe they make enough of a difference to compression to be noticeable, and composite gaskets + removing the outer head bolts is a reliability improvement. ARP head studs are a nice upgrade too, while you're in there... as are Mini exhaust studs (UNC into the head, UNF on the nut, plus brass nuts).

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Thanks to all for this. Rover V8's are new to me ..

FridgeFreezer - I'm on the Old Worting Road behind the Fire Station .... mine is the light green Land Rover 110 Dormobile seen going around the Ring Road 🙂  Would love to pick your brains before I start pulling bits off and also thanks for the hints on minor modifications. I think Range Rover Classic cast iron exhaust manifolds may also be a good upgrade. My engine had SU's with the funny air injection pipes into the heads to try to get emissions down ... 

I want to keep the 3.5 block ..  I have some friends in the US who have first refusal if I sell her and they want matching numbers. Also my 110 has solid discs front and drums rear and I don't want to go into axle changes etc ... 

She was bought to tow a car trailer for other toys (Ford Pre Crossflow engined) but has so far failed miserably .... after lockdown you can have a go and see just how bad ... 

I'm very confident mechanically, come from an IT tech background and being locked down has given me way too much reading time to do "MegaSquirt Armchair Engineering". I *really* like the Thor conversion but also have the "calling" to do a V3 sequential for lots of non Rover reasons (Ford 302 based !)

I think I'll do the first rebuild with the 9.35:1 pistons and the composite gaskets with the exhaust change (its a bitch getting to the starter motor with the current strange manifolds) ....and see if I can get a reasonable amount of performance. I've got all the bits in stock on the shelf. Also I've got a house move later this year and I'm trying to reduce my stock of engines ....

I was more "armchair curious" to know if the 10.5:1 compression ratio could be made to work with better fuel and ignition control (any MegaSquirt) but looks like a bridge too far ... I also hadn't realised Ethanol has a higher Octane ratio than petrol so may actually help ?

Thanks to everyone ...

 

 

 

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This is her on the only permanent four wheel drive rolling road with an entrance tall enough  !!  I couldn't believe how gutless she was and thought playing with timing and fuel would get me big gains .... not the case ... the drive home was painful ... then other things got in the way. 

The engine has done 80,000 ... bores are good, compression test good, distributor advance curve is correct ... mixture good ...  eliminated as much as I could ..this is how I got to to the engine rebuild with compression ratio increase. 

Just wanted to keep the topic on track 🙂

IMG_1153.png

Edited by Chris Gale
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10 hours ago, Chris Gale said:

also have the "calling" to do a V3 sequential for lots of non Rover reasons (Ford 302 based !)

Don't do it, MS3 is ludicrously complicated and you'll gain nothing. Sequential is for idle emissions and maybe F1 cars.

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Thanks ...  I'll save the pain for the 302 then (we need traction control and a few other things) ... so should I do MS1 or 2 ?  

Also the Thor manifold based conversion looks really neat and doesn't seem to have any minus points ?

I've bought a couple of Rover V8 books that will be arriving shortly to continue the Armchair R&D ...

V1 Urgent - Looks like extract and dismantle - chemically wash to get rid of the black gunk - check the heads again - hone block - 9.25:1 pistons - composite gaskets - ARP studs + bolts -  Mini studs -  Range Rover Classic manifolds - fit the trigger wheel to the bottom pulley whilst out.

V2 Armchair Pipe and Slippers - Thor + MS + Range Rover in tank pump and new fuel lines ...

 

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MS1 will happily run anything, MS2 gains you a bit of resolution in terms of injector opening time and more options to configure wrongly ;) folks here running MS2 report slightly smoother running.

MS3 is a hot mess of insane over-complexity with seemingly no lessons learned unfortunately. I'm pretty sure even MS1 can do basic traction control.

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On 2/1/2021 at 10:46 AM, FridgeFreezer said:

MS1 will happily run anything, MS2 gains you a bit of resolution in terms of injector opening time and more options to configure wrongly ;) folks here running MS2 report slightly smoother running.

MS3 is a hot mess of insane over-complexity with seemingly no lessons learned unfortunately. I'm pretty sure even MS1 can do basic traction control.

For the price difference between MS2 and MS3 (about $120 difference in the kit price from DIYAutoTune), I'd say get the MS3 - although it has more features you don't have to use them - there's just more options in TunerStudio that you can leave disabled. You get onboard logging to SD card which can be useful when fine tuning without needing a laptop, built in USB so don't need a serial adaptor and a few other bits and pieces. If you are considering LPG at any point it will also support that much better. 

If you did decide to swap engines / add extra stuff you have the option of extra IO if you want it, via the MS3X daughter card. Resale values would also be higher should you part it all out at some point in the future as well... 

 

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On 1/31/2021 at 1:09 AM, smallfry said:

Do you mean  the four barrel Weber and manifold, or a two barrel 38DGAS conversion that they used to do by modifying the standard SU manifold ?

3.9 camshaft is not great for carburettor engines.

10.5 pistons were only fitted to early engines, and will not take much more than 5500 rpm. Lots of modern engine run that high though.

Cant comment on Megasquirt as I have no experience of it personally, but from what I read on here, it can be very problematic unless you are a tech genius.

I put a 3.9 cam in a 1974 1:8,25 and it runs very well. It is well known and common upgrade.

5500rpm on a Rover V8 with a 3,9 cam? The standard spec lifters are rated @ about 5000rpm anyway!

 

In the meantime switched over to 1984 SU's, complete 3.9 exhaust system without cat's and late type oil pump and everytime that old V8 gets better. 😉

 

I would go for the 10,5 pistons with composite gaskets. That will give you a CR in the region of 1:9,75

BUT: you need to get the preload on the lifters right: you need longer push rods or something else to compensate for the increase of distance between cam and heads.

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Thanks all ... starting to get this armchair engineering project progressed !!

10.5:1 with composites looks like the best option ... with ARP bolts and adjustable pushrods ... 

Gearbox etc stay as is after going through the Ashcroft Calculator ... but a move from 15" + crossplies to 16" wheels will happen sometime ..

Thor manifolds with fuel rail - injectors - TPS sensor are on the kitchen table !!

Anyone got any photos of how to get the fuel tank out of a 110 ?! Mine has the Dormobile floor and kitchen unit so hope it drops out the bottom of the chassis rails ? 

Cheers

Chris

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Yes it comes out from underneath - just make sure you keep all the little spacers/washers/bushings together in the right order and remove all the wires & vent/return pipes from things before you drop it. Also, the less fuel sloshing about in it the better.

Oh, and MARK the pipes/wires (maybe take a photo) so you know what went where ;)

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On 1/31/2021 at 11:38 PM, FridgeFreezer said:

Don't do it, MS3 is ludicrously complicated and you'll gain nothing. Sequential is for idle emissions and maybe F1 cars.

MS2 can run a V8 semi sequential with spark and fuel, which will easily meet/exceed requerments. 🙂

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On 2/7/2021 at 2:27 PM, Chris Gale said:

Thanks all ... starting to get this armchair engineering project progressed !!

10.5:1 with composites looks like the best option ... with ARP bolts and adjustable pushrods ... 

Gearbox etc stay as is after going through the Ashcroft Calculator ... but a move from 15" + crossplies to 16" wheels will happen sometime ..

Thor manifolds with fuel rail - injectors - TPS sensor are on the kitchen table !!

Anyone got any photos of how to get the fuel tank out of a 110 ?! Mine has the Dormobile floor and kitchen unit so hope it drops out the bottom of the chassis rails ? 

Cheers

Chris

Maybe skim the heads (0,5mm?) to compensate for the thicker composite gaskets is an option too... And take 9:75 Vitesse pistons.

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