turbo performance Options

[nsyr]

I know there a few people out there with turbo 4's. Does anybody have any performance or reliability figures.

[Sammy]

I really got to ask, did that person who told you that you can't keep the heads on have any real experience with turbocharging a type 4 or was he just talking out his ass like most people when it comes to turbocharging?

The reason I ask is that I absolutely do not agree with him at all. I see so many posts and opinions about turbocharging that are bogus it amazes me.
Someone reads a book or article on the subject and they instantly become an expert on it.

I don't consider myself on expert on the subject but I do have knowledge backed up by research and trial and error. Real world experience.

I tend to listen to guys like Jake and Evil ED much more than I would someone who just studied the subject without actually trying any of it.

That's the problem I have with college business professors, most of them are just regurgitating what they read and have no real life experience. Oops, went off on a tangent.

The limiting factor when turbocharging a type 4 is cooling and head design, not the head studs. Maybe if some fool tried to run 2 bar or something it might be an issue.
On my engine I didn't have any head leak problems and I didn't even run head gaskets. I just lapped the cylinders to the heads and that worked up to .7 bar boost.
The head port design is not optimum but a turbo will actualy compensdate for this poor design up to a point. Boost will make the heads flow more, it will even make the stock cam work very well up until the valves float. But it creates lots of heat in the form of back pressure and the heads have a hard time getting rid of that much heat.

Keeping the combustion temperatures and the head temperatures and oil temperatures down are key to keeping it alive.

If you can prevent pinging and keep the temperatures down the thing will run and run.

In my experience around .5 bar is the sweet spot for a non-intercooled 914. That's where it seems to work very well without overstressing anything or creating too much heat. You can go over that but then you start getting closer to the ragged edge.
With enough cooling and if it is rich enough to control pinging and combustion temperatures you can run it up to around .6 bar reliably on pump gas without having to back off very much on the timing which can acutally create more heat if not done right.