1256 Turbo conversion and Oil Cooler fitting?

[SL1256]

I suspect i will be using Megajolt for the ignition with Edis Ford coil pack,with Ren5 GTT carb and standard Ren5 GTT turbo. I now have a possible source of an engine to use for the build,first will be stripping that down for the usual checks then find some low comp HA pistons and breath on the head,general clean up of the ports and open out the exhaust ports to allow for better flow. Then the tricky bits like making manifolds,plumbing to turbo and getting it to run properly!

great fun ......when everything goes to plan

HB estate - Where did you get you oil feed to the turbo? Im thinking oil pressure switch

[griffonmark]

I can see the allure in turbocharging a 1256cc engine but surely the engine will never survive 100bhp even if you could get the massive boost and correct fuelling required. The guesswork and expense involved would lead me to a modern Vauxhall 2.0 turbo engine which can be bought cheap as a known package. Then all you've got to worry about is shoehorning. Or how about copying a panther kallista set up? All components should be obtainable off the shelf but even then I don't think they were the most reliable of set ups. I would prefer to turbocharge the less stressed and more revvy 1800 slant four. Has anyone ever done that?

[SL1256]

Ive tried to weigh up possible engine transplants,looked at going with ca18det engine and box from a 200sx but decided i didnt want the hassle....tried to buy back my old c20xe from my mate but he's just about to put into a corsa.....apart from those two options there isnt anything else that interests me! Aside from hunting down a dead Magnum 2300 and put the whole engine/box/subframe assy....which i doubt i will find,id rather just fiddle with the 1256 engines for now.

For the last couple of years,all ive worked on is Land-Rover diesel engines and Rover V8's.......im enjoying playing with small 4-cyls again

[griffonmark]

I was going to suggest a Rover V8 but I thought you might think I was going a bit too far. However, too far is just where I'm about to go. Next project is to shoehorn an Sd1 V8 into my other Griffon. It still has Magnum underpinnings though, with a LSD, so I still consider it a Vauxhall at heart.

[lambaj]

Sometimes you just want to find out how far you can go with the original stuff. I 1st rebuilt my 1057 '90' engine, then built exhausts, then overhauled a 1256, then worked it over, unleaded, ported, cam, exhaust, twin carbs, lightened, balanced, valve train changes etc etc. Ran that for a while, then went further and hopped up another cam stage and yet another exhaust full system.
For some reason, the need for sticking with some degree of originality was important to me, so I tuned what should have been under the bonnet. Then I took the next stage and engine swapped to the blown V6.

Now I'm playing again with my hot 1280cc engine, and have decided that the ratty old CD150 brabham setup can go, and have stumped up for a 45, Looking forward to how it behaves.
As for 100bhp on an OHV, should all be fine if its built, bolted and balanced correctly. A certain Mr Blydenstein once told me that a ohv will see 7000 rpm ok when balanced properly. I have only taken mine to about 6500...... and judging from the condition of the engine on inspection, 7000rpm should be a reliable max. Time will tell.....
'A' series engines can run well over 100bhp, and they only have 3 bearings too....

So, its ultimately horses for courses, but I fully understand the "getting a quart out of a pint" tuning mentality. May not be as fast as a transplant, but for some reason it seems to be purer....

Food for thought
Tony (HA21)

[hb estate]

I suspect i will be using Megajolt for the ignition with Edis Ford coil pack,with Ren5 GTT carb and standard Ren5 GTT turbo. I now have a possible source of an engine to use for the build,first will be stripping that down for the usual checks then find some low comp HA pistons and breath on the head,general clean up of the ports and open out the exhaust ports to allow for better flow. Then the tricky bits like making manifolds,plumbing to turbo and getting it to run properly!

great fun ......when everything goes to plan

HB estate - Where did you get you oil feed to the turbo? Im thinking oil pressure switch

the blanking bolt @ the rear off the head much shorter oil pipe than the presher switch adrian miller sells the pistons in varos over sizes £45 +p&p best to check whats already in your engine be fore odering my fist donor engine when dismantled turned out to b already 60 thou over bord

[viva2300]

I'll agree with that Tony
My 1380 a series runs at 102bhp. I did strap the centre main though. but other than that and a lighten & balance, the bottom end is standard, and will rev to 8000rpm.
I reckon a centre main strap would work well on the 1256 too along with a lighten & balance. I would go for a set of Omega pistons too & maybe strapping the con rod caps along with ARP bolts i reckon 100bhp would be no problem.
Paul

[hb estate]

whats a center main bering strap???

[lambaj]

Hi

Extracted from the web, and "A" series main strap looks like this:

Here are instructions:

This strap is used to give support and strengthen the centre main bearing cap on small-bore engines (850/998/1098cc). It helps counter the problems caused at higher rpm where crankshaft flex (‘whip’) causes the standard cap to move (‘shuffle’) leading to bearing failure and possible breakage of the main bearing caps. In particular, where higher rpm than standard will be the norm – i.e. in excess of 6,000rpm. Especially where this is for extended periods.

The standard centre main cap needs to be machined by a competent engineer or engineering shop, as the finished surface needs to be absolutely flat. The final finish being ground where practical.

The cap should be milled straight across along a central axis from one retaining bolt-hole to the other using a 1.03125”(1 1/32”) or 26mm cutter with as small a corner radius as possible, down to the original bolt head flat surfaces. This is necessary, as just milling the cap completely flat will remove the centre thrust washer locating slots.

Once machined, check the strap for fit to the cap, increasing the edge chamfers as necessary to clear the corner radius left.

When finally assembling the engine, ensure strap is fitted with adjusted chamfer edges to cap, fit new bolts supplied and torque down to standard setting (threads clean and dry, 65lb ft.). Higher torque settings are not necessary.




I am pretty sure you cannot just buy one of these off the shelf for the OHV, and it would require modifications to the oil pick up pipe too, but it shows the principle.
I am not sure how viable it would be to strap the big ends, even if you ground a lot of meat off to fit the straps, the weight change on the big end may cause some extra high levels of stress in the crank. I cannot find any reference to this process - can you add anything ?
As for Omega pistons - Hee hee !! I wish......
Again, been looking for 20 + years, never seen a set of performance pistons for the OHV....

Still, main strap is a good idea - might look at that for mine

Tony (HA21)

[SL1256]

Thank you Tony for pointing me in the right direction regarding the oil cooler take-off, i ordered one last night and have my eye on a s/h 13-row cooler on eblag in nearly new condition which will do nicely. Now all i have to do is save up for the oilstat (having no income sucks )

The engine build is on the backburner at the moment due to the above but as soon as im back in gainful employment it will actually start!

Steve