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

[ArtechnikA]

Next up, twin turbo?
Run a turbo off of each side... Cyls 1,3 & 2,4

have a look at the sizing and the firing order before deciding this is a good idea ...

[airsix]

UPDATE:

Well, I drove it to work today. I'm really liking this boost thing. (IMG:style_emoticons/default/biggrin.gif) But the 'not going past 4k rpm' part got old real quick because that's when thing are just starting to really get fun. If you recall this is a self-imposed limit because I haven't finished converting the fuel pressure regulator with a boost-reference port and the injectors can't keep up past around 4,700 rpm. So tonight after getting home late from work, and spending time with Jamie and Kimberly I went back out to the garage to try to figure out a way to get the broken drill bit out of the fuel pressure regulator adjustment bolt. No joy. So after wasting a bunch of time on that dead-end I scrounged up an 8x1.25 bolt and made a new one (square cut threads and all). This time I drilled it right by making a tooling plate to hold the bolt perfectly vertical. That worked. Bored it straight down the center. I then drilled the head of the bolt to press-fit a piece of tubing for the vacuum hose. So far so good. I got it back on the car and adjusted the pressure to 30 psi. Went to hook up a vacuum hose and the stinkin tube pulled out. Ok, going to have to solder it. Can't believe it pulled out. I had to press it in with an arbor press. Oh well. I need a vacuum hose 'T' anyway (I was going to temporarily steal the line to the BO valve). Tomorrow I'll grab a 'T' on the way home from work, solder the tube into the bolt head and see how it works.

This boost stuff is really a new tuning experience. I thought I had my ignition advance curve roughed in pretty good but I found out today that it'll need some more work. I had roughed it in by doing some second-gear pulls from idle to 5k rpm. But what I found out today is that I'm going to need to refine the boost-retard settings further because If I rip through the gears there is more boost the second time through the rpm range. For example if I'm loping along in 2nd @ 2,000 rpm and floor it I might have around 3 lb. boost by the time I get to 3,000 rpm. If I take it up to 5,000 rpm and grab third I find myself into a lot more boost than I was at the same rpms in second.

Ed(s), and others who've done this sort of tuning... What kind of advance settings are/were you using? My ECU will allow me to subtract from the advance angle at various manifold pressures. I put in a linear boost-retard from 0 at atmospheric to -10 at 10psi. (For example the advance angle at 3,000 rpm and 10 psi would be 27 - 10 = 17 degrees). I really don't know if this is even anywhere near close. (no intercooler)

Thanks for keeping the chatter up. This is fun.

-Ben M.

[Evill Ed]

UPDATE:

Well, I drove it to work today. I'm really liking this boost thing. (IMG:style_emoticons/default/biggrin.gif) But the 'not going past 4k rpm' part got old real quick because that's when thing are just starting to really get fun. If you recall this is a self-imposed limit because I haven't finished converting the fuel pressure regulator with a boost-reference port and the injectors can't keep up past around 4,700 rpm. So tonight after getting home late from work, and spending time with Jamie and Kimberly I went back out to the garage to try to figure out a way to get the broken drill bit out of the fuel pressure regulator adjustment bolt. No joy. So after wasting a bunch of time on that dead-end I scrounged up an 8x1.25 bolt and made a new one (square cut threads and all). This time I drilled it right by making a tooling plate to hold the bolt perfectly vertical. That worked. Bored it straight down the center. I then drilled the head of the bolt to press-fit a piece of tubing for the vacuum hose. So far so good. I got it back on the car and adjusted the pressure to 30 psi. Went to hook up a vacuum hose and the stinkin tube pulled out. Ok, going to have to solder it. Can't believe it pulled out. I had to press it in with an arbor press. Oh well. I need a vacuum hose 'T' anyway (I was going to temporarily steal the line to the BO valve). Tomorrow I'll grab a 'T' on the way home from work, solder the tube into the bolt head and see how it works.

This boost stuff is really a new tuning experience. I thought I had my ignition advance curve roughed in pretty good but I found out today that it'll need some more work. I had roughed it in by doing some second-gear pulls from idle to 5k rpm. But what I found out today is that I'm going to need to refine the boost-retard settings further because If I rip through the gears there is more boost the second time through the rpm range. For example if I'm loping along in 2nd @ 2,000 rpm and floor it I might have around 3 lb. boost by the time I get to 3,000 rpm. If I take it up to 5,000 rpm and grab third I find myself into a lot more boost than I was at the same rpms in second.

Ed(s), and others who've done this sort of tuning... What kind of advance settings are/were you using? My ECU will allow me to subtract from the advance angle at various manifold pressures. I put in a linear boost-retard from 0 at atmospheric to -10 at 10psi. (For example the advance angle at 3,000 rpm and 10 psi would be 27 - 10 = 17 degrees). I really don't know if this is even anywhere near close. (no intercooler)

Thanks for keeping the chatter up. This is fun.

-Ben M.

Ben, 1 degree of retard per pound of boost is a good guide line.
I found that I needed to be at 24 degrees for anything over 8-psi. Your system is more adjustable than mine was so you will have to experiment. I would start a little higher, 24 vs 17 and back it down as necessary. Too little timimg is no good either and will cost you power.

Regards,
Ed

[Mark Henry]

Congrats Ben, nice job! (IMG:style_emoticons/default/smilie_pokal.gif)

Are you using a 2 bar MAP sensor?

[iamchappy]

Ben, have you considered a 5th injector ( cold start valve) that would richen up the mixture. Fire the injector at 3 to 4lbs by a pressure switch.
That is what I did with my setup and found no need to retard the timing more than a few degrees if any even at 9lbs boost.
With the map sensor you have great tune ability but the extra fuel getting thrown down it's throat brings on measurable performance you can feel and detonation safety, this can be easily plumbed into the system.

[airsix]

MORE UPDATES:

Wow, thanks for all the great tips guys. Yes, Mark, I'm using a 2-bar MAP sensor. Ed, thanks for the info on ignition angles. Wow! Sammy, you are right (more on that in a second).

So yesterday and early tonight I worked on modding my fuel-pressure regulator for a boost-reference port. I got it finished around 9:00pm. It works perfectly. Fuel pressure rises pound-for-pound in synch with the pressure on the reference port. So now I've got 30psi fuel pressure off-boost and up to 40psi when on-boost.

So I set my pressure to 30psi and went for a drive. I had to back-out a whole lot of boost-enrichment I had programmed in before fixing the pressure regulator. I did some low and mid-range off-boost tuning to smooth things out because there was some part-throttle bucking in one spot where it was going rich. Got that resolved and it drives pretty nice now. Ok, time to really get on it. I went to some isolated road (Ha! I remember Sammy talking about his special tuning road. (IMG:style_emoticons/default/smile.gif) ) and started pulling some full-throttle runs, watching the WB-O2 and laptop to tweak the boost-enrichement where needed trying to at least get somewhat of a constant mixture. At this point I was just trying to get the mixture at WOT roughed in to between 11.0:1 to 12.0:1 across the whole rpm range because when I started it was all over the place (mostly rich). This process was easy at first, but as I got the mixture closer and more constant the power just started to POUR ON. It was getting harder and harder to tune further because there is enough power now that things are happening too fast to drive, watch the WB-O2, and laptop at the same time. Cool. I've now got the mixture hovering around 11.5:1 under all boost conditions (and around 12.7:1 off-boost). Any thoughts on optimum boost mixtures? I don't figure 11.5:1 is optimal, it's just a target I used tonight to rough things in.

It looks like I might need to go to larger injectors. The Subaru injectors I'm using are now hitting 100% duty cycle at around 5,900 rpm. I might try a few more pounds fuel pressure but that's not going to be a permanent solution. I think that will be easier to deal with than a 5th injector. At least now I can run the engine up to almost 6k rpm under full boost. WOW! I honestly NEVER thought I'd like this 1.7, but I can't deny that I'm having a ball with it now. Sammy, you are so right about the torque curve. I'm used to the power dropping off rapidly above 4,500 rpm, but now it just keeps getting stronger. The higher it gets the harder it pulls! Its really a new experience. (I can only imagine what Chapman's car is like!)

One other thing that was a pleasant surprise - after working the mixtures into the ballpark I started getting boost much earlier. I'm now seeing possitive manifold pressure as low as 2,200 rpm!!!!!!

Ok, it can't all be good, right? The bad new so far is:
1) two small oil leaks (will fix Saturday)
2) choking on the price of synthetic oil
3) burning through a tank of gas this week faster than I can say "YEEEEEeeeee HaaaaAAA!!!!"

[iamchappy]

Turbo 914's are way to much fun. The air has been cool and damp the past few days, I cant get enough of the extra grunt the engine exhibits under these conditions.
I know what you mean in regards to keeping an eye on the laptop and gauges. My first few runs all I had to watch was a tach, boost and a/r gauge and wasn't able to, when I finally stared at the boost gauge I was seeing 18lbs of boost due to the wastegates lines hooked up wrong. Running at 9lbs made it easier ( 18lbs was just insane ) to catch the readings on the gauges, All I watch now is the tach. Quarl gave me a red led instrument light which I wired into the 7th injector to let me know when it fires. At night I think the cops are on my ass as it floods the whole interior with red light. He thinks they need to be brighter (IMG:style_emoticons/default/wacko.gif)
Keep up the good work Ben, enjoy the new found toy. (IMG:style_emoticons/default/mueba.gif) (IMG:style_emoticons/default/driving.gif) (IMG:style_emoticons/default/aktion035.gif) (IMG:style_emoticons/default/burnout.gif)

[airsix]

Keep up the good work Ben, enjoy the new found toy. (IMG:style_emoticons/default/mueba.gif) (IMG:style_emoticons/default/driving.gif) (IMG:style_emoticons/default/aktion035.gif) (IMG:style_emoticons/default/burnout.gif)

Thanks Chapman (or do you prefer to go by "chappy" or Loyal, or...?)

I know this is just a meager 1.7 that is probably only making "2.0 w/ cam & headers" type power, but you have to understand that for 12 years (off and on) I've only driven 80hp 1.7's. Never rode in a 2.0, a six, or any other non-anemic 914. As I've worked on my driving and improved the handling of the car it's made the power issue all the more frustrating (the better I made the car handle, the more gutless it felt). I know this little turbo isn't going to set any land-speed records, but it's so much more enjoyable to drive now there's absolutley no comparison. Guys with warmed-up 2.0's might be thinking "big deal", but it's all relative. I've been underpowered for so long that I feel like I've been let out of a cage.

-Ben M.

[fiid]

Aye, Ben,

Do you live at any kind of Altitude?? It strikes me that you may not have even been developing 80HP if you are at a few thousad feet. The turbo will also provide atomspheric compensation for you :-).

Seriously cool that you are realising actual performance gains. Do you have a GTech or something that you could get a quantitative read from?


(IMG:style_emoticons/default/smilie_pokal.gif) (IMG:style_emoticons/default/smilie_pokal.gif)

[airsix]

Aye, Ben,

Do you live at any kind of Altitude?? It strikes me that you may not have even been developing 80HP if you are at a few thousad feet. The turbo will also provide atomspheric compensation for you :-).

Seriously cool that you are realising actual performance gains. Do you have a GTech or something that you could get a quantitative read from?

Nope, no altitude here. I'm at only 550 ft above sea level. I can't imagine driving a 1.7 where I grew up (5,000ft ASL = 75% power x 80hp = a scorching 60 hp)

I don't have a G-tech, but I do have 2 things that might get us some real numbers. A few years ago I bought the "road dyno" software that lets you record a sound file off your ignition pulses and plots a torque/hp curve based on your inputs (final drive, gearing, tire diameter, frontal area, etc). I had a heck of a time trying to get a clean enough recording though. Now that I'm running electronic ignition I might be able to get it to work. Recording the electronic ignition with a digital cam-corder should be clean.

The other option is that I've got the rpm cable for the LM1 wideband sensor. It will log rpm over time and dump the data to excel. If I knew the math I could extrapolate hp/torque from that using the same inputs as the "road dyno" software. Anybody care to give me some tips on that front?

I'm still going to try making a video of a run so you can see/hear it. I took my Dad for a ride (he drives a 300zx) and he got a real hoot out of it. "Do it again, Do it again!!!" (IMG:style_emoticons/default/biggrin.gif) Now he wants me to turbo his pickup and he's eying a supercharger kit for his 'Z'.

I'm having a great time with this, but in the back of my mind I can't help but think about the Subaru motor you're working on. That gives me goosebumps.

-Ben M.

[lapuwali]

How much boost are you running? I thought you'd said somewhere you're running 10psi, but you also say you think you're getting only 30% more power. 6psi should give about 30%. For 10psi, 50% sounds closer to the mark, unless you also substantially lowered compression to get it to run 10psi of boost w/o an intercooler. If the internals are stock (which it sounds like they are) and you are running 10psi, then you should be getting something close to 120hp, which is pretty damned impressive.

[airsix]

How much boost are you running? I thought you'd said somewhere you're running 10psi, but you also say you think you're getting only 30% more power. 6psi should give about 30%. For 10psi, 50% sounds closer to the mark, unless you also substantially lowered compression to get it to run 10psi of boost w/o an intercooler. If the internals are stock (which it sounds like they are) and you are running 10psi, then you should be getting something close to 120hp, which is pretty damned impressive.

I used Ray Hall's turbocharger calcualtors to estimate the power. What I did first was put in the bore, stroke, # of cyls, max rpm, compression ratio, and ZERO boost. Then I adjusted the volumetric efficiency number until it showed power output of 80 hp. That was my "stock" baseline.THEN I added boost to the calculation to get my hp estimate. If I recall it showed 114-116hp (no intercooler and my WAG for the compressor efficiency). With intercooler the estimate jumped up to 145hp. So, it looks like I've got to figure out how to get an intercooler working! (IMG:style_emoticons/default/smile.gif) I figured the 116hp was a "best case scenario" so I said 110hp. I don't exepct anything to come out as good as the calculations since this is all home-spun by some dope with a hammer and a welder.

I checked my datalog and the wastegate is keeping boost at 1.621 bar, so I'm not at the 10lb I stated. It looks like it's closer to 8.9-9.0. I haven't rigged up a boost controller so it'll stay at that level for now. I might leave it there permanently. The engine might be living on borrowed time as it is. Giving me a boost-knob to play with might not be wise. (IMG:style_emoticons/default/w00t.gif)

-Ben M.

ps - Some kid in a Mazda-something heard the BO valve this morning on the way to work and tried to get me to play. Too bad I'm more mature than that and just ignored him. (Ok, I really REALLY kicked his ##s, but don't tell (IMG:style_emoticons/default/happy11.gif) )

[cha914]

UUUUMMMM...

1.62100 bar = 23.5106173 pounds per square inch

I hope that is a typo...or I am real interested to see how long this motor lasts (IMG:style_emoticons/default/smilie_pokal.gif)

Great stuff, keep us posted!

Tony

[airsix]

UUUUMMMM...

1.62100 bar = 23.5106173 pounds per square inch

I hope that is a typo...or I am real interested to see how long this motor lasts (IMG:style_emoticons/default/smilie_pokal.gif)

Great stuff, keep us posted!

Tony

Nope, not a typo. Remember, you are breathing 1.0 bar right now. Add 9 pounds to that and you've got 1.621 bar. (IMG:style_emoticons/default/wink.gif)

-Ben M.

[lapuwali]

MAP is 1.6 bar, not "boost". You're running 0.6bar of boost. Terminology can be confusing. Interesting calculations. I was basing my 30% number on what other cars have done with a 6psi non-intercooled supercharger or turbocharger on the dyno. However, you're right in that the VE for a Type IV is actually fairly low. A 1.7 should make a lot more than 80hp unboosted. 50hp/liter is 1950s level efficiency, and most of the figures I was using for comparison were at least 1980s level efficiency. (IMG:style_emoticons/default/biggrin.gif)

I wonder how much improvement there would be in increasing exhaust flow, a known sore point on the Type IV. A bit of port work on the exhaust side could pay big benefits, and would probably improve cooling even with the turbo. Still, 110hp is something to be proud of with such a simple setup. You've certainly got me thinking, as I also have just a 1.7, and don't want to spend big dollars on a Big Four, or a Six, nor do I really want to go water-cooled with a Soob or the like.

[aufaber]

Wow, great job!

You probably want to loose that red oil line asap though, we had two 914's blow that exact same hose. We lost one engine because of it. That hose's out sheathing gets very gummy and soft when hot and just ripped.

i know Jeff had a custom hose made up pretty cheap for the supply side of his Turbo.

-Aaron G>

[airsix]

Hi Aaron! Actually I've got a real oil-line (hard-line w/ banjo fitting on turbo connected to a section of 12,000psi flex-hose on engine side). The red hose is just a piece of heater-hose I'm using for a lame attempt at cooling the bearing housing. One end is connected to the evap-canister port on the impeller and the other end is connected to the water jacket on the turbo. The engine fan forces a fair amount of air through the hose for what I hope is a little bearing-housing cooling benefit. Yeah, I know. My Dad's response was "nice try".

-Ben M.

[airsix]

MAP is 1.6 bar, not "boost". You're running 0.6bar of boost. Terminology can be confusing.

Sorry about that Tony and James. You are right, I should have said my manifold pressure was 1.6 bar, or said my boost was .6 bar. My bad. (I think Tony was hinting to me about my error and it went right over my head).

-Ben M.

[mightyohm]

What is the effect of compression ratio on the max. boost you can run? Why are most turbo motors ~7-7.5:1?

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.

[ArtechnikA]

What is the effect of compression ratio on the max. boost you can run? Why are most turbo motors ~7-7.5:1?

it's complicated but it comes down to a couple of things. first - it's all about cylinder pressure, and when you start out with a compressed mixture it's like having more mechanical compression.

second - since the supercharged mixture is A Good Thing, and the more of it the better, high compression ratios require small combustion chambers which doesn't leave much room for mixture. with a larger combustion chamber, there's simply more volume in which to cram the air/fuel mixture.

Corky Bell's "Maximum Boost" and Hugh MacInnes' "Turbochargers" are excellent resources for independent research.