Turbocharging a V12

Hi, I’m embarking on a low boost turbo V12 project and I have a Pre HE.
I would like peoples opinion on whether HE or Pre HE is better suited to forced induction?

I am clueless, but the flathead preHE have much higher hp/torque potential.

You’ll get better exhaust valve flow with the pre-H.E. head. Presumably you’d want to upgrade pistons and conrods anyway, so the originals are irrelevant.

You’re setting yourself up for a lot of work there. Without thinking about the engine internals, minimum would be intake and exhaust fabrication, aftermarket ECU, and a bunch of rolling road time to set it up. I would think that just improving the exhaust and intake flow, plus a well set up ECU, would give you a good performance boost without adding the complexity of a turbo.

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The H.E. heads also have much higher compression than the flat heads, undesirable for a boosted engine. As high as 12.5:1 compression. I don’t know how suitable the flat head combustion chamber is for boost, but it likely is better than the H.E. if for no other reason than the flow characteristics.


Thanks everyone for your input. Just what I was after. I plan to do a lot of the fabrication myself and I believe the key will be a good ECU and a clever tuner

Stephen, turbocharging is probably the cheapest way to get decent power out of a V12. If your pre HE V12 is in good condition and you are going for low boost you may not even have to open it.


Then theres this one

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LongJohn, my thoughts exactly

That is truly wild. Not the prettiest but a great concept

10psi boost and 650hp from a 5.3 V12 sounds a bit optimistic. Maybe 15-20psi…

If that’s really a Tremec T-5 in there, that car is probably developing more torque than it is rated for.

A bit taken from the FB page this was about 1 year ago.

‘I designed and built(and sometimes drive) this car. We have seen over 900HP on the dyno, but run lower boost on the track depending on the day. Currently upgrading intercooling system and converting to outboard rear brakes while replacing the broken diff(it already chewed up a Tremec TKO600, changed to G Force GSR 4 speed(NASCAR gearbox) which is handling the torque…”

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It doesn’t say which Tremec. It maybe a TKO