Advice - 12A turbo build - ideas, opinions please

[Eeyore]

gday all - well my Capella is nearing completion but for certain reasons i will be without a license for a while so i was thinking i might ad to the project

anyway at present its a 12A PP, 48IDA, RX4 4speed, open stock diff... thats about all thats important... anyway i have a friend whos' family buiness has been building and racing rotaries for years and they all agree the logistics of turbo charging the existing engine is just stupid.. shame cause i was kinda optimistic - i also wouldnt mind running some big boost for fun.. not possible or slight chance? ideas?...

what about an actual 12A turbo motor or a stock 12A, decompress it and built custom exhaust manifold, get a intake manifold... dunno just throwing ideas here

anyway it short i just wanna stuff around, cheap fun, see how far i can push things... so throw some ideas my way

[Dazz]

I tend to agree that turbocharging the existing motor is fairly pointless.

I guess it really depends on how much power you're looking for. Even to set up a basic combination will cost quite a bit. A totally std 12A Turbo engine with a cheap computer will make around the 200hp (flywheel) mark with a bit more boost. Which I would imagine is short of what the PP already makes. By the time you buy fuel pumps, surge tanks, etc etc you'd be up around the $3,000-$4,500 mark pretty quickly.

If you want to go to the expense of making manifolds, going to a hi-flowed Series IV/V Turbo, extra injectors, intercooler, etc etc you will be up around the 300hp (flywheel) mark. But that is not really any longer a cheap excercise.

In my RX-2, I've got a totally std non rebuilt import 12A motor, the std turbo was hi-flowed (55mm comp wheel, bored out exhaust housing, back cut turbine wheel etc), a new exhaust manifold was made, it has a 50mm ida throttle body on a Weber manifold, four injectors, a front mount intercooler, and a MoTeC. On MoTeC's engine dyno on normal premium unleaded (in 1995) it made 228hp at 6900rpm and 190ft/lbs at 6000rpm (also makes 180ft/lbs at 3000rpm) on 9psi.

Whilst not being a huge hp animal, it is extremely drivable, makes 6psi at about 1700rpm, is noise legal, and when I used to drive it to work every day used to average around 11L/100km of city driving.

If you were going to rebuild an engine, and not use the std turbo or manifolds, then a 12A RX-7 motor would be better to use anyway. Don't worry about decompressing it unless you want to run stupidly high (20+psi) boost.

A nice mild ported std comp 12A, with a Series IV/V turbo, cooler, decent computer etc should make around the 270-300hp (flywheel) mark on about 12-14psi quite easiyl, safely and reliably.

My advise would be that if your going to turbo it, budget to do it properly otherwise the results can be less than reliable, and thus enjoyable.

[THRSTY]

whats wrong with using the current motor to turbo?

i know the above may sound stupid, but depending on where the intake ports are positioned it can work well.

im guessing theres still a heap of overlap and so isnt ideal for turbo applications, but if u wanna have a go why not? surely the turbo will be of some benifit? it might not be ideal, but for a cheap setup, use the original motor and carb, add turbo and piping (suck through design). most will go straight out the exhaust, but im sure it at the very least will help scavenging and overcome any intake restrictions

[Dazz]

If your current PP has carbon seals it is a very good idea not to turbo it, as it will not have apex seals for too long!

[THRSTY]

ahh lol forgot about that