Ben's 914 TURBO Official World Premier, 'cuz it didn't blowd up. Options

[airsix]

Would a 73 1.7 with its reduced compression ratio be better than an early 1.7? I think it's 7.5:1 vs. 8.5:1 or something like that.

'73 1.7 has 8.2:1 compression, so yes, it may be better suited to turbo applicaitons than a '72, but not by much. 8.5:1 is still plenty low for mild turbo-ing IMHO.

-Ben M.

[lapuwali]

It's not really the compression ratio that's the problem, it's maximum cylinder pressure, which, all else equal, is higher with a higher CR. Add boost, and you're raising the peak pressure, since the starting pressure is higher. Ultimately, the limit is detonation/spark knock. Lowering the CR lowers the peak pressure on-boost to keep the engine below the detonation limit. The disadvantage to that approach is you also kill power and efficiency off-boost, which is where a street engine spends most of its time, anyway.

Older OEM turbo engines often had low CR as a conservative safety measure. It allowed an idiot owner to put regular gas in the car and not kill the engine completely, just cause enough knock to remind them not to do that again. It also allowed the car to be run at very high ambient temps with the AC on while driving up a steep grade, the worst possible combination. With modern engine controls, spark timing can be retarded and boost regulated more effectively to keep cylinder pressures down while still having a high CR. This kind of thing was hard to do in the 80s, and pretty much impossible in the 70s, so early turbo cars just ran low CR. With a knock sensor, you can control knock pretty well and keep CR and boost relatively high, and still allow an idiot owner to put in a tank of regular on a 100 degree day while getting ready to drive west out of Denver and keep the engine safe by just disabling most of the boost. It's the advent of these electronics that are allowing turbos to reappear in OEM apps after they nearly vanished for awhile. Modern systems are now so good that turbo lag is nearly gone completely, and it's often hard to tell the turbo is there at all.

Ben did absolutely the right thing in getting a programmable engine management system on the car first, and getting used to working with it, before attempting a turbo. He can get fuel and spark set perfectly and responsive to boost w/o too much worry of melting things.

[Mr_Chu]

Before I comitted to a 6 conversion for my car.. i thought if turbo would work in a 914. I had so many negative responses about it... but damn.. for those who have the 914 turbos, you really proved them wrong. I would have totally went with the turbo system instead of a 6...

But since i have the 3.0 liter 6 waiting.. i have to steer that way.. (IMG:style_emoticons/default/wink.gif)

[iamchappy]

3.0 - 6 Turbo, if you still choose to steer in that direction Mr. Chu. (IMG:style_emoticons/default/happy11.gif)

[Andyrew]

Theres no substitute for Cubic inches except forced induction...


Hecks ya when you mix em..

[airsix]

James, that was some great info about turbo application history. I always wondered how it was that late '90s turbo's like the Eclipse and Supra could run such high boost levels and such high static compression ratios. What you say makes sense.

Thanks for the compliment about my strategy. I'll tell you what, many times over the past 2 years it didn't seem like the right thing. It's been a steep learning curve dealing with the EFI and learning to tune with it. I think the best money I've ever spent was that LM1 wideband O2 sensor. Tuning without the wideband was like taking tests and only being told if you passed or failed, never knowing what you did right or wrong. Using the wideband O2 is like getting your test back so you can see what problems you missed.

I hope others do this sort of project. If anyone else wants to do a turbo-4 I think you could do it very inexpensively with a good junkyard turbo and megasquirt EFI. I am happy with my EFI, but I bought it pre-megasquirt. Is Kit Carson's EFI going to support forced induction? If so, I think one of those two systems would be the way to go if you're on a tight budget (Perfect Power makes some nice mega-feature ECU's if you want to spend a few $100 more). Let's say you go with megasquirt, a junkyard turbo, and an LM1 wideband O2 for tuning (I can't stress enough the value of the LM1). You could easily keep the whole project under $1,000 if you do the fab work yourself. My total cost to date including the EFI is about $750. Megasquirt would have been a couple $100 less. That's cheaper than carbs! Don't underestimate the cost of "the little stuff". After the EFI was on and working it cost another $175 to do the turbo install. Only $50 of that was the turbo its self. $125 was all the little bits and pieces of nickle and dime stuff (hose clamps, fittings, exhaust tubing, etc).

-Ben M.

ps - so what do you guys think? Intercooler or water-injection? (The age-old problem: I just can't think of a practical way to get airflow over an intercooler)

[redshift]

With a knock sensor, you can control knock pretty well and keep CR and boost relatively high, and still allow an idiot owner to put in a tank of regular on a 100 degree day while getting ready to drive west out of Denver

Holy shit dood, you just made my ultimate puking scenario into a painting!


(IMG:style_emoticons/default/barf.gif)


m

[Andyrew]

Intercooled and water injected.

Intercooler will work just like an oil cooler, it doesnt NEED extra air flow.. it just could really benifit from it..

A fan would be a good choice... like a 70% throttle switch or WOT switch to turn it on...

Water injection is another safe guard, and for oh 300 bucks your good

Andrew

[lapuwali]

I'd do an intercooler first, and just lay it across the top of the engine, or across the front of the engine bay. Perhaps do a GT-style all-mesh engine lid to help with temps. If you look at a number of the "across the top of the engine" OEM intercoolers (2nd gen RX-7 turbo, turbo Soobs), they have a scoop to get air in, but no where for the air to GO afterwards. Measurements on the RX-7 setup showed the scoop could basically be closed off with no real difference. Airflow would be nice, but just the intercooler itself will help. Ducting more air into the upper engine bay is (and should be) something to do, anyway, and can be done w/o ugly scoops visible from the outside. Adding one would cost much less than $300. There are lots of junkyard intercoolers out there, from any number of Japanese turbo setups. Some are pretty small, too. If you wanted to get quite fancy, you could try to obtain (or even fabricate) a water/air intercooler. Build a watertight box around a regular air/air intercooler, and circulate the water with an electric pump to a small radiator (oil cooler type) mounted more into the airflow. One possible place for it is directly in front of the engine, below the front shelf. You'd catch under car airflow (which is considerable), yet be in front of all of the exhaust heat, and no having to carve up a trunk or run really long hoses.

Water or alcohol injection always seemed like a drag-racing hack to me, and I think is mostly suitable if you're running really high boost for short spurts. An intercooler will improve VE some, and should allow a modest boost increase. 12psi with good VE should give you 150hp or so, which I'd think would be plenty from an elderly 1.7.

[andys]

Older OEM turbo engines often had low CR as a conservative safety measure. It allowed an idiot owner to put regular gas in the car and not kill the engine completely, just cause enough knock to remind them not to do that again. It also allowed the car to be run at very high ambient temps with the AC on while driving up a steep grade, the worst possible combination. With modern engine controls, spark timing can be retarded and boost regulated more effectively to keep cylinder pressures down while still having a high CR. This kind of thing was hard to do in the 80s, and pretty much impossible in the 70s, so early turbo cars just ran low CR. With a knock sensor, you can control knock pretty well and keep CR and boost relatively high, and still allow an idiot owner to put in a tank of regular on a 100 degree day while getting ready to drive west out of Denver and keep the engine safe by just disabling most of the boost. It's the advent of these electronics that are allowing turbos to reappear in OEM apps after they nearly vanished for awhile. Modern systems are now so good that turbo lag is nearly gone completely, and it's often hard to tell the turbo is there at all.

Addition to the history:

The '63 and up (not exactly sure of the start date, but that should be close) Corvair Corsa had only a pressure retard diaphram on a Delco mechanical distributor. 6 degrees retard is what I recall. Carburetion was a side draught Rochester single barrel ahead of the turbo. No waste gate. CR was I believe 8:1 with open chamber heads, and a nitrided crank;the later Corsa's were making 180HP. This, on a '60's vintage air cooled motor. They were fast with a few easy mod's.....'65 Corsa with wrapped exhaust, and a two barrel down draught carb on an ICO manifold, and this thing was as fast as an stock early Z28. Ran El Mirage at 131MPH in a standing start one mile run; that was in '68 or '69.

The '63 Olds Jetfire had an aluminum 215 cu. in. 215HP V8, 10.25:1 CR, and 8 lbs boost. It too had a Rochester side draught carb ahead of the turbo, but with an elaborate alcohol injection system. Dash pot on the trottle plate kept it from snapping shut under declleration to keep from pulling down the turbo and avoiding pulling oil through the carbon seal on the impeller shaft. Featured a water cooled impeller housing, and a differential pressure waste gate. It was manufactured by Air Research. I ran one of these set up's on a six cylinder '69 American. A friend owned the Jetfire, and it was really quick in it's day (it was what was considered at the time, a compact car). Had AC, no knock sensors, no electronic boost or timing controls, and no detonation.

Lots of other turbo stories, but this will do for now.

Andy

[lapuwali]

The '63 Olds Jetfire had an aluminum 215 cu. in. 215HP V8, 10.25:1 CR, and 8 lbs boost. It too had a Rochester side draught carb ahead of the turbo, but with an elaborate alcohol injection system...Had AC, no knock sensors, no electronic boost or timing controls, and no detonation.

All very true, but in 1963 the gasoline coming out of the pump wasn't 85 octane fuel with a 10% alcohol content, and they could run the thing at 10-11:1 AFR w/o altering any smog police, as they're weren't any.

GM fooled around with turbos in the mid-60s (and were pioneers largely forgotten today by some who think it was Porsche and BMW who brought turbos to the street in the 70s), but they'd given up on them for a very long time, not to reappear on gasoline engines until the 80s, and even then I can only think of the GN. American Iron is not my subject. It's also interesting that it still took 25 years for turbos to appear on cars at all, since they were first developed in aircraft applications before and during WWII. Perhaps they were still classified post-war (they certainly were during it).

The history of turbos on production cars is an interesting one, with lots of ups and downs. Big hit in the early 80s, then they died off again for awhile (partially replaced by superchargers), and are now making a comeback.

Interesting you should mention the '63 Olds engine, since that's the Buick/Rover V8 so beloved of many Brit-car fans. All aluminum pushrod V8 of modest (by American standards) displacement that was very light (less than 300lbs). If it would fit, it would probably be an excellent 914 engine.

[andys]

Well, the quality of the gas is certainly a factor. That 11.5:1 Z28 I mentioned would be tough to find gas for these days, no question. Turbo's didn't take in the '60's because big cubes were by far a lot cheaper to produce than were high tech high HP small motors. If you notice, that was the evolution back then (US cars). Turbo's re-appeared in an effort to bring small (fuel) efficient motors to a higher HP/performance level.

The '63 Olds had different (and better) heads than the Buick version. The only reason the Buick heads became popular as a retro on the Olds, was that they had smaller chambers (Buick used dished pistons) and you could get way more compression for cheap. Another reason the Buick got attention, was that it was easy to swap the dished pistons in favor of the Olds flat top's. Consequently, the Buick was more popular amongst the backyard hotrodders. Notice however, that the racers of the day tended to use the Olds motor. It really was a sweet power package. The NA 215 V8 four barrel motor was rated at 195HP.

As a 914 swap, these were somewhat popular early on....maybe someone here can chime in with who made the adapters. In the mid '70's, the woman that cut my hair had such a 914 with the 215 aluminum V8 motor (her husband built it, and she occasionally drove it.......I still have the vision of that car; it was a green '73).

Andy

[aufaber]

ps - so what do you guys think? Intercooler or water-injection? (The age-old problem: I just can't think of a practical way to get airflow over an intercooler)

Air-Water intercooler... (IMG:style_emoticons/default/cool.gif)

http://images.earlyapex.net/Jeff%20Turbo/mvc365f.jpg

[ArtechnikA]

Air-Water intercooler...
http://images.earlyapex.net/Jeff%20Turbo/mvc365f.jpg

Jeff never did post any delta-T numbers on that, long-term or short-term, so i must remain skeptical on the implementation.

water/air intercoolers certainly can be made to work -- 934's and early 935's had them...

[airsix]

UPDATE:
I got mixture and advance angle squared away today and started paying some attention to other things. Did a WOT blast from a dead stop through tripple digits and logged the data from the ECU. Intake temps hit 158 degrees F (ambient temp was 76 F). How much do you think I could knock off that number with an average-ish intercooler? 2 years ago when I got the turbo I also picked up an Eclipse intercooler I have not installed. I'm still trying to figure out how to get some air over it once I put it on the car. I'll try to figure something out this week. I'll keep you posted.

-Ben M.

ps - Sammy, I'm glad you commented about Turbomania - I didn't realize it was dedicated to vw forced induction. I always assumed it was about turbo's in general and didn't know it was focused on aircooled vw applications. I'll have to get a copy of that one.

[Mueller]

(IMG:style_emoticons/default/pray.gif)

congrats Ben....I'm jealous..


according to Corky Bells book, water-injection is a "band-aid", and that you must have something wrong with the system if you need to use it...the biggest gripe I have with his statments about it is that he does not go into any detail why.....I do know that the water will displace air/fuel which is not a good thing powerwise

here is a link with some more information from a company that favors water injection

RB Racing..info and calculators

[airsix]

Hey Mike,
Hope you had a nice vacation. Don't know if you've really got anything to be jealous about - YOUR daily driver has more than double the power! (IMG:style_emoticons/default/smile.gif) It's fun though. Much better than before.

-Ben M.

[Mueller]

the 911 is an okay daily driver, but I "really" miss driving the 914 (IMG:style_emoticons/default/sad.gif)

I played with the 914 yesterday...had it running good for about 20 minutes then the damn ECU starting resetting itself causing it not to run anymore....the only thing I can think of is that it has something to do with heat...the ECU never got hot and was far away from any heat sources...I don't know, mabey once the coil gets hot it builds up resistance that could be freaking out the ECU signal

I plan on installing the crankfire ignition this week.........

I have another one of those turbos you are using, think you can plumb both of them* and run them in parall using a "Y" ??? (IMG:style_emoticons/default/smile.gif)

*use the one exhaust outlet like you have, but have a "splitter" to drive each turbo and then have the compressed air meet up again...let me know if you want to try it, just pay for shipping and it's yours to borrow

[airsix]

Wow, great info Sammy!

Mike, I forgot to warn you - you are going to need to make a heat-sink for your wideband O2 sensor. Just cut a 4 or 5 inch square of copper plate, drill a hole in the center just large enough for the sensor threads and then bend two sides up at a slight angle. (This is per Klaus @ inovate) Then sandwitch it between the sensor and the bung. I did this and all is well now, but without the heatsink my sensor was freaking out if I was hard onto the boost for more than a few seconds. I'd get "Sensor Timing Error 08" and have to reset the controller, but with the heat-sink installed now it's fine.

-Ben M.

[lapuwali]

had it running good for about 20 minutes then the damn ECU starting resetting itself causing it not to run anymore....the only thing I can think of is that it has something to do with heat...the ECU never got hot and was far away from any heat sources...I don't know, mabey once the coil gets hot it builds up resistance that could be freaking out the ECU signal

If it is heat, I'm thinking it's more likely to be heat from the board itself. You say the ECU never got hot, but what about the individual components? If the processor gets too hot, it will reset. If the injector drivers are getting very hot, they may be driving up the temperature of the processor.

Are you running resistor plug wires or resistor plugs? Still have the case open on the ECU?

I'm in the middle of assembling my MS. Perhaps trying a different unit might help pin down your problem. Once I manage to get it completely assembled (still have to hunt down some parts that didn't show with the order), I can bring it by and we can see if it also has the same problem.