2.8 Turbo Engine Build
 

I'd like to share this build. Maybe there's something of interest here for you. This has been mainly a DE car since '95, but it does drive to (and back from) the track over the roads.

It's a 2.8 (70.4 x 92 mm), built on a sandcast aluminum case. I had the case bored for 2.8 in the 1980s.

It uses a 964 oil pump and 993 squirters.

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• stock 2.4/2.7 crank, crack tested
• shot-peened Porsche rods, raceware rod bolts

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• JE pistons running on Porsche 2.7 cylinders with US Chrome Nikasil plating
• Currently 7.0 C/R
• It still has all 24 Dilavar studs!

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• 2.4 E heads, chamfer cut, ported to 39 mm, bored for low buck EFI injectors

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The cams are not great for this motor, crane p-306, but I love the results! Intake lift is 12.55mm at the valve, intake advertised duration is 306 degrees.

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I was thinking of trying some SC turbo cams I have stored.

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Nice build, more details please!

^ yes! I love reading about unique builds.

Thanks for the kind words. This one was low-buck start to finish.

So ANDIAL ported the heads and Pacific FI ported the 911E throttles to 40 or 41mm.
I chopped up some aluminum 3" square and 2-1/4" round tubing, 1/4" thick to form the intake manifolds. Thanks to the Evans Brothers in Elburn IL for CNCing the flanges. Tech-Weld in Elburn zipped them up (with some pre-heat).

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For the first iteration in 2001 the headers were Bursch 1-5/8 linked to a couple of small Garretts with internal wastegates. The plan was the intakes could be rotated 180 degrees to work with or without intercooler.

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In 2006 after some good advice from Midwest Eurosport, we decided to increase the intake square tube to 4" and link the intakes together. So the upper part of the 3" square tube was milled off, leaving a flat base to mount the 4". With the manifold open, it was possible to taper the inside of the runners, and screw 44 IDA trumpets to the flat base.

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Then the 4" tube could be screwed on (with prevailing thread fasteners and Loktite). There are six 2" pipes linking the intake to cooler because the air in both is very turbulent, so more pipes is better just here.

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Had some spare time and a lot of acetylene, so I chopped the Bursch headers into 40 pieces with a hacksaw and build some shortys that were suprisingly equal-length. About 13" primaries as I recall. Don't look too hard, if the welding doesn't nauseate, then the China wastegates should do the job. Turbos are now T03e hybrid (imported). Funny thing, I work for Honeywell.

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Two different oil drains here. The chain box drains worked, but the pipe or hose was so short there was no room to flex and assembly was difficult. The sump drain still works (now with two AN-10 fittings) but if I don't drive the car for a few weeks the oil builds up in the engine and comes out through the turbos, especially if the front end is raised.

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saved

Yep... subscribed as well.... very cool!!!!

I think this is the coolest build I've seen yet....

:cool: got to watch this with great interest...
Kozmo

What turbos do you run for the twin configuration? I see integral wastegates in your early pictures.

Thanks for the encouragement. I was afraid this build would be too far "out in the weeds" for the community. Just trying to have some fun without too many $$$.

At first the turbos were Garrett T3 with 50 compressor trim. Tried the .48 and the .63 turbine housings. Was trying to be conservative to begin with but everything turned out too small. The turbos, the fuel pump, and the injectors were too small. Was not happy with the performance.

The second iteration was China T04e hybrids with stage III or IV turbines. They are $149 each! Throw 'em out as soon as they get dirty! Injectors are now Summit 83lb/hr (a little too big). There's no boost until 3rd gear, but then it lifts up the front end in 3rd. I probably don't want boost any sooner for two reasons. One reason it would be too much torque for the 915 trans. Also currently not using 2nd gear on the track (RA and Blackhawk).

So loving the T03e compressors but maybe the turbines should be smaller for good spool. I would like to use KKK but the China parts are great because you can keep switching them until you find what size the engine likes.

I love this build! I've been thinking for years about doing something similar on my 914/6 race car. My enbgine is a 2.7L built on a sand cast case with MFI throttle bodies.

There is a gentleman on this board who also built a similar engine, a 2.5L as I recall, for his 914 a number of years ago. His car was featured as a budget build in Excellence back in the late 90s.

Keep the details coming!

Scott

Wow. You make mention this us a budget build but......

stownsen: It's possible to just 'ease into' the build. Initially, I dropped the C/R and switched to EFI. Just kept driving it that way! I know, that's not feasible with your race car. Then it was simple to adapt the turbos to headers later. On the intake side, I know some have pressurized the MFI stacks. Simple, but not sure how well that works. You would have some nice plenums sticking out of the engine cover! It would look a little bit 908.

quattrorunner: You have a good point. I would not want to know how much was spent over the years. But little by little...

that car is off the charts in coolness factor.

Thanks aschen. Whenever I have a choice A or B, I just pick the one that's cooler. Serious.

Nothing is too far out for this board.
Cool build.
Thanks for posting and sharing. I like when people play around without spending too much.
This is the way to learn as well.
Keep posting :-)

Here's the long version on 4 different injection systems that have been in this car. Probably too much information, but maybe something we can use.

So it started life as a 911 E with that wonderful mechanical injection. The sound with the air cleaner off was unbelievable. People kept asking "what you got in that thing".

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It was sad to remove the MFI pump when the 2.4 Mag engine was replaced with Aluminum 2.8L/turbo, but as I understand it is costly to re-calibrate the pump for 2.8L and to have it compensate for the turbo. Has anyone done this? Also there are no mounts on the early Aluminum cases for the MFI pump. I hear there is a fix for that however. Worst of all, the custom turbo intake meant no more great noises.
The MFI pump was replaced with an economical EFI system, the ACCEL DFI/Calmap (now Holley / Mr. Gasket).

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It worked best when programmed for synchronous batch fire (once or twice per engine rev). That way, there was naturally less fuel flowing at idle, because there was more time between pulses. It has a pure batch fire mode that just fires every 16mS regardless engine RPM, but that mode doesn't have enough flow range to match requirements for both idle and WOT.
Most of the EFI components came from Kinsler. Got some fuel rail stock, a bypass regulator, an electric high pressure pump, and filters. They also have some extensive write-ups how to design a racing fuel system (EFI, Lucas, Hillborn etc). I drilled the injector bores in the heads to fit EFI injectors.

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I didn't intend to spend any time on a dyno, but I felt that mass air flow meters (MAF) were accurate enough to meter the fuel without any dyno tuning. I created a fuel map that worked with MAF, not MAP. The ECU wasn't made for that but it was possible to create the fuel map with some math, spreadsheets etc.

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The ACCEL system worked about 7 years before going kaput. I recall using an oscilloscope to confirm that the injector drivers were actually inactive. In other words, it was not just due to a problem with a sensor. Overall, I would say the ACCEL system did the job. It just didn't have the features you expect from a modern system. Anyone else (that wants to admit to) using the ACCEL DFI?

So for the third iteration on the fuel injection I made a custom ECU!

It was another case of more time than money.

I wasn't after any particular feature except simplicity and to not require a dyno tune.

I felt that a MAF sensor could determine fuel requirements over a wide operating range, including boost. No other sensors were used! Not temperature, pressure, or RPM. I felt if there were any "flat spots" that could be addressed if they showed up.

The system actually worked well for a number of years for both road and track use. I never really got a wideband on it but the mixture smelled and sounded right in most cases. Plugs looked OK. One exception was cold startup could be sluggish, so I added a cold start button that would open the injectors as long as the button was pressed.

Details on the home-made ECU follow. Caution, hard-core Electrical Engineering content ahead!

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So the ECU circuit board is on the right in the photo above, the "Removable Target Board". The left side of the photo is the part that is used to burn a new program into the target. So this thing is tiny!

And cheap. It was $22 shipped. That includes a software development environment with simulator that targets the entire product range. I bought 4 of them.

The MSP430's are often used in bathroom scales and handheld instruments such as DVM's, but they have also been launched in micro-satellites (below). So cheap doesn't mean they are not capable.

There are a wide range of variants with many options available including wireless communications. I selected a variant that had an Analog / Digital converter to interface the MAF sensor and built in timers that had a Pulse-Width-Modulation (PWM) mode to control the fuel injectors.

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The only hardware required outside of the MSP430 board was a large FET to drive the fuel injectors. I selected a FET that was designed for this task. Specifically, it had a beefy body diode that was rated to repeatedly absorb the voltage spikes created every time the injector circuit opened.

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So the basics of the required C program were to read the voltage on the MAF, and multiply by a constant to get the correct pulse width on the injectors. This task it would repeat as quickly as possible.

There was one catch, however. The output of the MAF sensor is does not correspond to mass air flow linearly. Fortunately, both Pro-M MAF units I received came with a flow bench data curve that is the test results for that particular unit.

So it was the task of the C program to read the MAF value and using the table below, estimate (by piecewise linear interpolation) the instantaneous fuel requirements.

const unsigned int air_mass_table[17] = {0,17,63,126,205,306,439,612,834,1111,1445,1836,22 82,2782,3336,3952,4647};

const unsigned int air_fuel_ratio = 12; // air to fuel ration here ( const unsigned int max_fuel_pph = 498; // sum of rated flow for 6 injectors
const unsigned int fuel_trim = 0x00;
const unsigned int time_to_open = 0x00a0; // injector opening time


There was another fascinating issue to solve. When using large injectors in batch fire, they would be fired infrequently such as every 100mS, because you don't want the time the injectors are open to fall much below 2mS. The 100mS cycle time would cause a somewhat lumpy idle. As the MAF reading rose above idle, I kept the injector open time fixed at 2mS, but reduced the time the injectors were closed to get the correct PW and smooth the running. But at high RPM, it worked the other way around. It was necessary to keep the injector closed time at 2mS to maintain accuracy, and vary the time spent open. A fun lesson in one of the most basic functions of an ECU.

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So that's all there is to it. Far from a great system by modern standards, but probably one of the most simple we've seen.

This is why I love this forum. I've been following this thread with great interest since it was started. It just keeps getting more interesting and educational. And as a bonus I don't have to feel so bad about my welding skills :D. I'm just finishing the last of my exhaust fabrication. I'll post pix son as my ugly welds are dressed.
Super cool project. Thanks for posting.

I know how to use a wrench and some JB weld.
You amaze me.

Threads like this are why I am sometimes hesitant to post the work I do on my own car. I'm out of my depth here.

Very cool build! Looking forward to the conclusion.

Never. Dig in, give it a try. Even if you aren't happy with the initial results, you'll have fun, your skills will improve, and you can do it again. :-)

Crackin me up with the comment about the welding skills. That's really funny.

Yea, sometimes it gets really bad with DIY welding. I recently found a local pro that is extremely reasonable. Still working on getting new machine, lessons, practice, etc. however.

If there's time I have to make a thread on the home-made TIG machine! That's been my favorite welder for about 10 years at home. Didn't spend more than $100 on it. Well, there were a few broken welders laying around to use for parts.

Now that is beyond cool, making your own ECU and TIG welder! I like how you use your brains to find inexpensive solutions to complex problems. Once finished, better look out! I've been to the drag races and have seen homemade shade-tree road cars driven to the strip only to destroy some of those pro team expensive high tech trailer'ed cars. Keep up the good work and let no one discourage you. ;)

You most certainly do! http://www.sherv.net/cm/emoticons/fi...y-emoticon.gif

The fourth (and last?) injection system that's been used on this engine is the Megasquirt 3 Pro (MS3).

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MS3-Pro Standalone Engine Management System by DIYAutoTune.com

I'd say the up's are a broad feature set and low cost while the down's are that many don't appreciate the lack of factory support. Support is available on this forum:

Megasquirt MSEXTRA / MS3EFI • Index page

This system was set up to provide fuel only because the two Electromotive HPV units were still providing a powerful spark energy after many years of service. The HPV system was advertised to deliver 120 milli-Joules per spark at 10,000 RPM when new.

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This MS3 is configured for full sequential fueling using the excellent Clewett cam trigger. The trigger bracket can be mounted on either camshaft.

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Since the HPV ignition units were already crankshaft triggered by a Clewett 60-2 wheel, it seemed simpler to have the MS3's crank trigger interface the HPV's tach output rather than work out how to have the MS3 and the two HPVs all connect to the crank trigger in parallel.

Currently the main fuel table is configured to respond to throttle angle and RPM. Then, the table lookup result is multiplied by MAP pressure to compensate for turbo boost. The MS3 has a feature that reads AFR and tweeks the main fuel table as you drive. It seems to work! Still in the process of fine tuning the map (not my screen on this one).

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Some of the other features I'm using: wide-band closed-loop with AFR target tables, boost control, 2 knock sensors, injector timing map, SD card datalogging, MAF sensor (for reference). My custom dashboard below:

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If you are interested, there's a couple cool gauges here. The "Intercooler Efficiency" gauge is calculated using 3 NTC thermistor readings. The "Net Power" gauge reads the wheel speed sensor and uses a mathematical model that accounts for vehicle mass, air drag, rolling resistance, and drivetrain losses.

^^^^Awesome! This thread got even better! Love the cam trigger!

Wished I'd have went Pro. My MSII is full of features but lacks sequential which I now want to do for better MPG and throttle response.

Mike, if the car's in Peoria, keep us in mind when you need a chassis dyno to tune that on. We're by Broadway & Dobson in Mesa, close to the Loop-101.

I was recently considering asking you about that, Chris.

Noticed your dyno ability in another thread.

It's definitely safer than crusing the 101 with a laptop.

Thanks

So let's get some fresh headers under there!

The current ones are 7 years old, ugly and leaky. They're made from chopped up Bursch headers. They do have equal length 11" primaries however. Shortys are good for this application. Can't find a photo of them! Maybe there is a reason?
Personally, I would not be afraid to try the $75 Chinese collectors. Could they be cleaned up internally with a grinder? Heated and stress relieved? They are a bit long for making short headers however.

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I'm sort of into flat collectors now. They lend a vintage feel. And ground clearance Not really searching for horsepower now. Was talking with SPD exhaust in Rancho Cordova. They carry 321 stainless and their flat collectors look fine.

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Been sketching a new design. Specifying 25 degree entry to shorten the entire package. Specified rather thick 16 gauge 321 stainless because it's not a race car. This was drawn in FreeCAD BTW. Could do a lot better with it, just ran out of time.

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I'm sure Burns would make a similar product if asked. Just gotta find my own way. Your thoughts?

Prrrrreeeeettttycool!

Yeah, very cool.

Mike I scavenged my turbo's from the sump plate too. If yours works ok cool but just an FYI Jerry Woods makes a billet one if you need it. You really can't see it in this photo but I ran hard lines to it from my turbo's. Works great.



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Van, I particularly like that photo of your engine. Saw you at Road America.

Thanks for the tip on that sump plate and yeah, hard lines are better than hose when they are anywhere near the headers. Thanks.

Only one problem ever with the gravity drain. Oil drips from the turbos only if it has not been driven for a week. I keep it jacked up just to be safe.

Was planning on switching to a 930 scavenge pump.

Any theories?

I was thinking maybe the engine oil pump was worn out, allowing oil to fill the crankcase after a few days of sitting. Then the oil filled crankcase drips out through the turbo bearings. If I park it flat for a couple months, there will be two quarts of oil on the floor.

Mike
It has been a while since I have been to Road America. Last time I was there I had my yellow and purple GT 993 twin turbo and I had the 930 770 0911/009 0005 in the black BP liver like it ran at Le Mans.

The yellow and purple car I actually scavenged the turbos directly to the valve covers. But my turbos are on the side of the motor so that makes a difference (photos below) I had very small turbos on that car which is funny because with all the big turbo cars that were there I was 3 seconds faster than the next closest car. When I changed to larger turbos Johannes van Overbeek took the car out for practice at Willow Springs and didn't make two laps before the turbos went. I can only assume the larger turbo affected the configuration enough that my current set up would not scavenge efficiently so I put a Powerhaus pump on the motor which I think is a modified VW oil pump and it worked great. I think it was 600 bucks.

The engine in the photo above is from my yellow 935 chassis 930 670 0171 which is a converted 934 that now has that 3.2 liter twin motor. I never use the old 935 oil pumps anymore. I do a little case mod and put the new GT3RSR pump in and scavenge the turbos from the sump plate. I never have any oil build up issues from the car sitting.

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nM[U G~S` [/U]

Van, yes the yellow car was quite inspiring. I don't think we'll ever forget it.

I remember your team, also. I'm just not the type to come over and say hi.

So I'll try a new oil pump first (rebuilding the engine soon anyhow). Hopefully that will take care of the engine filling with oil while parked.

I wasn't clear before. It's a front mounted oil tank. So when the rear is jacked up, there is no oil in the engine, hence no drips from the turbos.

It's comforting to hear the GT3RSR pump doesn't mind the extra flow (and bubbles) from the turbos. Was wondering if everyone had good success at higher sustained RPMs. Never heard anyone confirm that before.

As I understand, those small turbos might be right choice at just about any track other than R/A. I'm kicking myself for starting small on the turbos and then upgrading everything over and over.

Mike, I built a test stand for my turbo 3.0. I found I had to adjust the height on the remote oil tank (I mounted it on uni-strut) to keep the oil from leaking out the turbo. Evidently, these engines are very fussy about oil levels.

Yes Mike I was running a Patterson tank up front.
Even with the small turbos and the car geared way too tall, 192 @ 7200, I still was in the mid teens about a 176 according to the wheel speed sensor at the end of the main straight. Was running too big of a front splitter so that slowed me down a touch too. Car had a couple of seconds in it for sure but it was still a blast even in Daytona trim.


I don't know that I have any answers Mike but if there is any info you think I can contribute I am happy to do so. Love your car.

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The group Road America photo from that weekend

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Pat: I see, maybe the front mounted oil tank changes the oil level. I guess one great thing about the 930 turbo scavenge pump is there is no way to siphon oil through the turbo oil drains like gravity drain can do.

Van: I'd say 176 is plenty fast into turn 5. Not all the Indy cars would beat 190. That big splitter is a good thing when the track turns downhill into the brake zone. I noticed the steering wheel has little effect in that area. The front end is lifted up by aero.

Thanks for the new pics. I think there are a few to study that we haven't seen before.