1971 Gold Metallic Project, The Turbo 1.7 Options

[SirAndy]

what determines the ultimate boost ?

Physics and math?
(IMG:style_emoticons/default/confused24.gif)

[djb]

Thanks for the response? About what power would 8 PSI make on a stock 1.8? Just trying to get a rough idea.

[Mueller]

Thanks for the response? About what power would 8 PSI make on a stock 1.8? Just trying to get a rough idea.

7ish hp per psi is a good number to on something like our older less efficient engines.

While that sounds small , the increase in torque is what you are really going to enjoy and use.

Going to be difficult to turbo the L-Jet on that 1.8.

[ConeDodger]

Thanks for the response? About what power would 8 PSI make on a stock 1.8? Just trying to get a rough idea.

+45 - 60

It makes a stock 1.8 feel like a 2270. I say that under this authority. I’ve owned a Raby kit 2270, and I’ve driven McMarks turbo. (IMG:style_emoticons/default/smile.gif)

[McMark]

Yup, torque is the big benefit. But think about the RPM range you're driving in most of the time. My car basically makes the most power in that range, so I can feel it taper off above 4500rpm, but that's okay with me. It's got greatly improved acceleration where I really use it.

I've run up to 12psi at times. You'll need to run aftermarket fuel injection to do it right. I prefer the MicroSquirt setup. The stock engine is a great place to start because they're relatively easy to replace if something blows up. My car has a stock 1.7 in it. But I'm eager to build the replacement engine that still based on a 1.7 but has a few tricks thrown in to make more effective use of the boost.

what determines the ultimate boost ?

When you run more boost, you get more heat. That's the short answer. But the heat can manifest in multiple ways. You could experience normal Type IV failures, such as valve failure due to heat. You can experience loss of compression and potential head failure if the combustion gasses are leaking past the sealing surfaces. Even if all those are holding strong, you may experience detonation/pinging which if left unattended can break/damage any and all parts of the engine (pistons, rings, rods, crank, heads, etc). But you can also combat the heat by using intercoolers, water injection, or other tricks. So like most things with engine design, there's no firm answer on how much boost you can run. And not many people have done this, so you're sort of always breaking new ground in the Turbo Type IV world. You won't have anyone to tell you you're on the right path. You just have to do your own research, and go for it and see what happens. And that right there is basically why I started with a 1.7. If my entire engine blows up tomorrow, I don't have much $ invested in that setup. So I can afford to push the boundaries and try some 'dangerous' tuning because I don't have much to lose.

[jim_hoyland]

What kind of boost did the Ray-Jay provide ? IIRC, 914rrr had one on the blue car

[McMark]

No idea. (IMG:style_emoticons/default/confused24.gif)