I was thinking the same thing. Back when piston engines used compound charging, they used an intercooler in-between the blower and the turbo and an aftercooler between the turbo and the engine. Plus some used water injection. This has allowed the engines to produce more than 3x the HP they were designed for.

Heres a guide for an OHV 1.6 Renault built
uses 34.8mm exhaust valves and 39mm inlets
http://www.tech-racingcars.eu/renault-5-maxi-turbo

Specifications

Group/Class B/12 Homologation number: B 267
Years active 1985 - 1986 Homologation start: 1/12/1984
Engine
Type C7K, straight 4cyl, 4 stroke, petrol engine located rear longitudinally vertical, in front of rear axle
Capacity 1527.4 cc WRC: x 1.4 = 2138.4 cc
Bore x Stroke (mm) 77.0 x 82.0
Compression ratio 6.7 - 7:1
Output power - torgue 360 HP / 6500 rpm 42.9 kgm (421 Nm) / 3750 rpm, (225 HP)
Main bearings 5 of 54.8mm diameter connecting rod length between centers 128mm, big end bearing diameter 47.6mm
Materials block: cast iron cylinderhead: aluminium alloy
Cams/valves 1 camshaft in block with overhead valves (OHV), chain driven 2 valves/cyl. - 8 valves total. 39mm inlet valve diameter, 34.8mm exhaust valve diameter. 24o angle between inlet valve and vertical, 24o angle between exhaust valve and vertical
Aspiration Garrett T31 turbocharger (steel turbine 65mm diameter, aluminium compressor 75.1mm diameter) with air/air intercooler, Bosch kugelfischer mechanical multipoint fuel injection

no pressure figures but they are out there somewhere if you look
gives you a good example of turbo size and valves
with a similar bore stroke you can get on A15.

This is what your celery will pay for if you cant build it :)
https://www.youtube.com/watch?v=FE6jACgIOxA

https://www.youtube.com/watch?v=93NUi2kjvow

heres the supposed 320hp Yatala dyno A series
https://www.youtube.com/watch?v=IXTn_rdtbhQ

The former golf had a setup with the blower first too. Hmmm kinda confusing. Older guys swear on putting the turbo first because the turbo can't handle the volume as well as the blower can hadle the pressure from the turbo, and you need a lot of bypass work if you put the blower first.

Also thinking of using the blower as the plenum for the sake of space (kinda like mosr pd charger kits. So can't use a charge cooler between the blower and the head, but I can mount a larger intercooler up front.

Rear mount turbo would also work in this case cause of the blower being closer...donno....
Any thoughts? Or am I scratching where I shouldn't? =P

If you are going to run 60 psi boost, a cooler after each stage is called for. Plus ADI (water injection). Gotta keep that little motor alive.

You'll want the turbo feeding the blower (with intercooling at each stage). The blower has a fixed displacement per revolution so having it round the other way would mean it's not doing anything once the turbo spools up.

If I was going to try this, and let's be honest - 500bhp from an a-series automatically carries with it the fact it won't last anywhere near enough to be a streeter, or even a circuit racer.

So if I was going to do it, just to get that figure, I'd run a lysholm compressor (since it will heat the charge the least) with a sizeable turbo feeding into it, intercooled but not aftercooled (if only because most of the charge heating will come from the turbo, relatively, and there'll be significant cooling effect from fuel being sprayed in after the supercharger stage. You could almost make a case for only needing a single stage of forced induction with what I'd have in mind.

But the 'ace up my sleeve' - well it's a drag race only proposition, so why not just run it on nitromethane and be done with it. Ultra low compression - probably 5.5-6:!, 40 or more psi boost and with enough nitro, the energy content of the fuel (when you factor in the sheer amount of fuel you would be shoving in there for any given amount of air vs 'regular' fuels and you'll end up with about double the power potential for the same boost levels. Since we know people have gotten over 300bhp from these motors turbocharged (probably on e85 or methanol) then 500 with a fully grouted block (or at least a 3/4 fill) to help the bore walls hold up and nitromethane is theoretically possible. Obviously forged pistons
decent rods, oil squirters to cool the underside of the pistons too, every other 'standard' mod you'd do for high boost, and probably magneto ignition just to get it to fire at full boost with that much liquid fuel in there, doable I'd think, but about as reliable as an election promise.

I'd give the thing maybe a solid handful of 1/4 mile passes before something let go, and you'd almost certainly be changing head gaskets after each pass. Hell I reckon you'd end up going through a good half dozen engines just getting the a/f tune on it right, as each dyno pull would be moving it closer to the end of its life.

It'd probably be the one time where you could actually get a 3 speed auto to work without being a detriment to acceleration on a 1.5 litre drag engine (not that I'd be suggesting the factory autos would be up to the task, remembering there is actually more than one model jatco out there, they aren't the same as the ones behind rb motors (unless I'm horribly misinformed))

lamb_daiquiri - Thanks for clarifying mate. I knew there was a reason turbo came first. I actually looked for Positive Displacement chargers that have their own runners, but seeing as how a lot of people are suggesting a put a cooler after the blower too, I'm lloking into ways to turn the plenum into a charge cooler. =) pretty brilliant thinking about it

Jmac - The direction you're speaking of is what I'd consider Stage 3. =P
See, at the moment I'm building a multi-purpose machine, based around mountain sprints, drivable on streets (if barely), with the occasional drag day where I could just change some suspension settings. I plan on building the engine around 102 octane as its sold damn-near everywhere around here and its not much more expensive than street fuel....well not anymore.

If I do go stage 3, I'd go methanol or propane, simply because its common and well-understood around here. But it would simply be for drags for obvious reasons.

I wouldn't waste money on a Jatco box. There aren't that many different Jatco auto's. My RB30 tore through 2 4N71E's and it only has 512nm. ...Not that I'd get that much from an A-Series =P
I'd rather just call the guys from PPgearboxes in Aus and have something concocted.

Currently looking into Quaife sequential dog box...Damn I am one poor bastard according to their standard...

I'm with Jmac, Id use the Jatco 3 speed if you use a supercharger and turbo. They can be made stronger than the 4 speed jatco and already bolt up to the engine. Would make a much faster 1/4 mile time than manual.

500 Hp is fairly optimistic. Why 500? It could be done but you will struggle with the A series head.

If you want a good start, you could buy my twin cam A series. I'd be happy to part with it for the right coin. It would make 500hp a lot easier than using an A series head. And a lot cheaper!

Simon, twin cam A-series??? Do tell, is it with the Mazda head or something else??

Tom

This bad boy if I remember correctly...