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

so far no one has stepped up to the plate and dyno'd thier cars that I know of.....the general "seat-of-the-pants" dynos report ~160hp to 180hp

if not abused too bad, the life should be just somewhat less than stock

"Everyone knows you can't turbo a type IV"

I estimate you can get a 20 - 30 percent gain on output without killing too much. I have been told that the problem is you cannot get serious boost on without the heads falling off (since they are only held on by 4 studs per cylinder and they tend to pull.

There are suprisingly few turbo type 4 engines around - it's not a delighfully easy thing to do - I tried it and gave up. I am doing a subaru motor conversion instead!

l8r,

Fiid.

funny how you consider doing that swap easier than adding a turbo to a Type IV

shouldn't you be riding your bike or something getting ready for your bike ride????

It's not really easier - it just gives a real return. I'll have 280 horse when I'm done. It should blow the doors off of a lot of things.

Fiid.

you suck !!! hahahaha

I'll be happy if my turbo 1.8 will put out 175hp...it'll still be a fun car to drive

oh yea...thanks for returning my phone call earlier in the week, LOL

Dude - I totally regret not returning your call -that was the day you were in the city right?

It's typically much easier to pry me from work with IM.....

Fiid.

Mueller, did you see what the monoball guy does on the 911 turbos?
A stainless steel ring with a step that is machined into the head. Third thing down the products list.

http://www.apfvilleneuve.com/racing%20parts.htm

I wonder if it would help with the sealing issues on the T4 heads?
Jake?

Hey Mark, no, I have not seen those SS rings before. I bought copper rings for my 2.0, but after talking to Jake, I am not going to run them.

Fiid, can you call me today/tonight? I need to pick your brain on your EDIS install....510-484-8700..thanks

i am considering the suby engine too. it wouldn't be that much more and it would be reliable. So, does anyone have performance figures for a 914 suby?

You can't put a Subaru engine in a 914

I can tell you that a 280Hp Subaru engine in a 914 ought to have a slightly better power to weight ratio than a Ferarri 360 Modena (if my math is right).

The 914 option is slightly cheaper, also.

Fiid.

Hell, if my plots work out the way they are in simulation I'll have a 270ish HP 10:1 N/A street engine to market!

Turbo that witha roller cam and you have over 500 with 8:1 CR!

Just wait!

Jake - do you think the exiswting head attachment mechanism will stand that kind of torture?

Fiid.

Something to remember about turbos - if done right they can nearly double the AVERAGE cyl. pressure without significantly increasing the MAXIMUM cyl pressure. (That, by the way, is awesome)

-Ben M.

The studs that come with Nickies should hold about anything.. The only way to know is to try. The key is cool running and keeping expansion down... Expansion and elasticity that comes with it kills the sealing capabilities. My heads are very beefy where they need to be, and being made from a chunk of Billet will definately help!

Well - if that's true - then it shouldn't be too much of a problem....

I spoke to a guy who seems to know what he's on about (he works with one of the regular competitors at the PCA AX) who was of the opinion that "you couldn't keep the heads on it". I never got as afar as why this isn't a problem for type I motors (I actually have never seen a type I motor) - but it seemed plausable. He seemed to think you could run sub 10psi without breaking too much, but when I ran the numbers through some of the turbo calculator programs, it looked like it would be hard to get enough power out of my 1.7 to keep up with 2.0s. I reckoned you could get 130 or so HP out of a 2 litre but it seems like it would be awefully easy to just turn it into a smouldering heap, and since a set of 2l heads can cost $500-$1000 by themselves - seems like a risky proposition.

A decent type IV rebuild just costs a lot of money - probably in the $5 to $8k range - versus the Subaru engine - as a JDM import crate motor costs between $600 and $1400, plus I can grab a new one any time I like.

If I could afford a built T-IV - I'd probably just bite the bullet and go for a 3.0, 3.2 or 3.6 -6 engine.

I might still turbo my 1.7 anyway - just for shitz and giggles.

Would be fun to try and get classed for the local PCA.

Stock Type IV heads do not compliment a Turbo... Not in any respect from the E/I ratio to the way they seal up..

My heads will allow a std Type I Turbo system to bolt right on, and they will staye sealed off- and hopefully without any extra studs!

I have Turbo combos- But I have never perfected one, and thats due to the exhaust port that VW gave us- its truly Satan!

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.

I wonder how many folks here actually have driven or ridden in a turbo 914? I had a '73 914 turbo back in '74 or so. Very torquey, and plenty fast enough to make it a fun car on the street. It really did transform the car without spending a ton of cash. I seem to recall boost was somewhere around 6-8psi. So I wonder how much faster would one want to go and compromise reliability with visions of big HP? I suggest perhaps one consider what to expect from a flat four air cooled pushrod motor, and stay within it's logical (read reliable) potential. You want 200+HP, then maybe an engine swap/conversion is your next (big) step.

As an aside, back in '69, I built a 6 cylinder '69 AMC (Rambler then) American with a T4 Air Research turbo with alcohol cooling injection. Originally ran 4 psi boost, then bumped it up to 8 1/2 psi. I put 75K miles on that car without one mechanical problem. Surprised a lot of people with that sleeper!!

Andy

I have never ridden in a 914 with a Turbo, but I have built Turbo TIVs for beetles and driven them..

I was not as impressed as I thought I would be..

It can be done, but not very easily and not without some pain along the way, and some "over engineering"

If you do it, run a 90mm bore- the heads will stay sealed off. My favorite one used a 90.5mm TI piston with a longer rod on one of my custom stroker cranks with a TI journal. It was actually successful.

My best guess is that with the crap they call pump gas now days, about 175 hp would be the realistic limit for a reliable stock turbocharged 2 liter type 4 unless you get really carried away with the design (read expensive). You should be able to get over 150 from a 1.7 without too much problem.
It just like most automotive issues, you can get improvements fairly easily up to a point, then it starts getting harder and more expensive. the higher you try to go, the more it costs.

That's one of the reasons why Jake's engines cost what they do, it aint easy to get that much power out of a n/a type 4 and have it last.

Because of the intake and port limitations a type 4 does not breath very well hence the very mild stock cam. I'd bet most of the power increases Jake gets are in the heads, cam, and valve train.


Pressurizing the intake overcomes those breathing limitations up to a certain point. one or two pounds of boost will make a surprizing difference on one of these cars. Figure at least 15 hp per pound of boost for the first few, then the increase starts to drop off. By the time you get over 5 psi you are prolly only going to be gaining around 10 hp max per pound of boost increase, maybe a little less. Above 7 the increase drops off more due to the efficiency of the turbo system and the heat of compression and the head design.

The stock intake port is amazing! The type IV exhaust port is amazingly horrible... Thats why the camshaft is of amazing importance.

I'd think intercooling was essential with an aircooled engine. I can't imagine why someone would try to run no intercooler on a turbo Type IV.

With a proper intercooled setup, most turbo cars show about a 50% increase in torque for boost pressure of 50% over atmospheric, which is exactly what you'd expect. Double the pressure, and you get double the torque. The increase doesn't stay linear like this, and perhaps with an unmodified Type IV head it would drop off even before the 2x mark, but the rule holds up well for "normal" boost levels on street cars (below 20psi).

And it's often torque, not peak HP, that really rises nicely in a good turbo setup. The current WRC cars, all turbo 2.0 engines, have an intake restrictor that clamps HP to 300hp, but they also make something like 500ft/lbs of torque! The area under the curve will continue to rise with boost pressure long after the peak has hit the ceiling.

Sammy,

Well said (though I'm not sure about that 15HP/lb boost)! When I first started messing with turbo's some 35years ago, an engineer at Garret advised me that the most noticeable gains are the first 3 or 4 lbs boost, and that for a street car, that's usually plenty good enough. Go more, and things start getting increasingly more complex. As for intercooling.......low boost levels keep the heat of the intake charge low as well, so you can run comfortably without one (they are advantageous though). Another tip I got from a local Indy competitor way back when, was to not bring the boost in at too low an RPM, as it puts a tremendous amount of load dwell at poor rod angles.

This (to me) all centers around what you expect, and what you want coupled with a good measure of reality. If you want to build a techno wonder with all the (expensive) components and systems, it is do-able. If you don't want to go HP crazy, a nice safe and affordable system is very possible, IMHO.

Andy

Intercoolers are not magic, they are just like most mechanical devices. They offer a performance increase in some cases, but at a cost.

Even the very best designed intercooler will have some restriction. if they didn't they wouldn't cool very well. This restriction reduces the efficiency of the turbo and can and will increase turbo lag.
The trade off is that they allow the tuner to run a little more boost because the cooler charge does not increase the combustion temperatures as much as a hot air intake and it is more dense.

BUT...... if we study the law from that guy names boyles or boils or whatever,
air doesn't get very hot if you only compress it a little. It is not linear, prolly more like exponential.

At around 3 psi boost you would most likely not have any benefit from an intercooler. The intake air would prolly only be about 10 degrees over ambient (guesstimating from past ezperience here, cut me some slack) Probably just the opposite, you would have negative effects from intercooling at that low of boost. The down side would outweigh the upside.

Even as high as 4 or 5 psi (depending on the turbo efficiency rating) there is little benefit to an intercooler.
At around 6 or 7 psi it starts to make a difference and is justified but at that point you usually need to look at the rest of the engine to see if it can go much higher in boost anywho. These numbers are approximations and generalities and there will always be an exception.

My SC is a good example.
I'm up to almost 7 psi with it with no pinging and no problems, but if I get into the boost for an extended time (like two full passes through the gears on boost) the intake system absorbs enough heat that it gets "heat soaked" and I notice a loss of performance and sometimes even a ping or two. In that case an intercooler would be of a benefit at as low as 6 or 7 psi boost.
I found the threashold and do plan to build a custom intercooler. If I were to keep the boost down to 4 or 5 psi I prolly wouldn't bother with the intercooler.
I also plan to recurve the dizzy to take out 5 degrees advance and also install another hobbs triggered injector. With all that i predict I can get above 8 psi, but I doubt I can go much higher than that reliably.

Plus the big question is, where the heck do you put an intercooler in a 914 without hacking the poor car all up? a 911 is relatively easy, a 914 is not. The trunk is about the only logical place and that would require a whole bunch of tricks and scoops and holes and louvers to get enough air flowing over it to keep it cool.

I've seen successful intercooler installations in some cars (not 914s) behind the rear wheels. Works very well in mid-engine cars. There's a fair amount of airflow into the wheel wells. I don't know if anyone has done any good airflow studies showing airflow into the area below the rear trunk. You could also do a water-air setup and run the water radiator up front.

I wouldn't look on the intercooler as a magic power device, but as a magic longevity device. Anything you can do to reduce charge temps on an aircooled engine has to be beneficial.

I think there is some truth to what my source is saying, although I don't think he's an expert on the topic.
Please bear in mind the the "keeping the heads on" problem is related to 12 or more psi of boost, which is quite a significant amount, and more than most people in this thread seem to be talking about. I am certain that lower boost pressures - 4-8psi can be run without too many problems, although that also means you aren't going to get giant horsepower.

Some people believe that the word turbo means 20psi boost, and to others it means no boost at all and atmospheric compensation (Read: so your performance doesn't go to crap in denver). Similarly, people have different ideas about what a good power output is.

I think you can make a 914 significantly quicker using a mildish turbo setup without too many problems. When you feel the urge to get the boost beyond 9ish psi, I think it will start to get difficult. This is all my opinion and is no way backed up by testing or real world knowledge - apart from the people having different ideas thing.

I wanted more than 200hp, and to never (or very rarely) do valve adjustments on my car. This, plus the cost of performance tweaks on the type IV engine (I have $1000 or so in my 1.7 already - just to get it running at a reasonable temperature and to get FI bugs worked out). means that a T-IV solution isn't going to work for me. I do ffeel bad about creating another hybrid, but I don't care about it as much as my local PCA does.

At least the Subaru engine is also derived from the Type I! So it shareas a great great grandaddy with all the porsche motors.