turbo engine tuning secrets -
featuring original research

By Josh Straub, 2009


Key Ingredients to a Fast Truck

Syclone Modification Stages

Stage 1:
How to Get a Stock Truck Deep in the 13's

Tuner's Guide to DataMaster

Real World Tuning Example:
Vortec/PT67GTQ Syclone on C16

Performance Roadmap: Syclone 4.3L Turbo V6

3 Bar Chip Tunes for Download

My 1991 Syclone

11.45 @ 117 Budget Build Spreadsheet

Vortec Heads Budget Spreadsheet

Racing Videos

Turbo Grand Prix

My 1990 TGP


Unfreezing Frozen Windows Applications
Stage 3
  Real World Tuning Example:
Vortec Heads/412 Cam PT67GTQ Syclone on VP C-16 at High Boost
A classic example of the difference between "chip tuning" and "whole vehicle tuning"


The Truck

Preexisting Problems

Sunday's Goal

Initial Testing on 93 Octane/Alky

Problems Draining the 93 Octane

Tuning for High Boost on C-16 Race Fuel

    Part 1- Problems Tuning
    Part 2- Strong Results
    Part 3- "Drivetrain Tuning"
    Part 4- Pushing Things Too Far

The Truck - Low 11s, Looking for 10s

On Sunday (April 27th, 2008), I met up with a local Syclone owner for some chip tuning. His truck is a summer time daily driver/street warrior built mainly for fun beat runs on the street. The stock transmission and engine endured an astonishing amount of abuse and lasted 130,000 miles!! He bought his truck close to the time I bought mine (spring 2001) and it has since had many good & bad performance modifications, along with eating 6 professionally-built 700-R4 transmissions.

Finally the stock 140,000 mile engine spun a bearing. Now it has an RPM shortblock with:

* stock block/crank, upgraded to 4 bolt mains
* forged SRP pistons/Eagle H-Beam rods
* PT6780H (GTQ) non-BB 67mm Turbo, stock exhaust manifolds unported
* Vortec heads (unported), intake manifold unported
* Comp 09-412-08 Camshaft, 5500 RPM
* Custom full size aluminum front-mount Air-to-Air intercooler, (we never noticed a power increase with this unit over the stock IC)
* 50# PTE Injectors, old non-progressive SMC "rectangle tank" dual nozzle alcohol injection (100% Methanol)
* Ostrich emulator/Ultimate chip BIN custom realtime wideband tuned by me
* built 700-R4, Precision Industries Vigilante multi disc lockup converter "2800 RPM stall"

In 2006-2007, I did a ~2 day custom wideband tune with him on 93 octane pump gas/alky and 20+ PSI for street beating. In 2007, his best run was 11.39 @ 116 at 22-23 PSI, about 19* max WOT timing, and a transmission problem causing the converter to remain unlocked. 60' times of 1.58 on ZR-1 Rims with BFG Drag Radials in the rear.

Preexisting Problems - "Band-Aid Fixes" Come Back to Haunt

I remember him telling me months after I tuned it, that it was suddenly reading WOT AFRs in the 14:1 ratios on his PLX wideband gauge. Coincidentally this is also when he ran his best times of 11.39 @ 116. I couldn't believe he would really be running so lean without detonation, but it was even more surprising how fast the truck had run. Ultimately he found the problem when he replaced the Bosch wideband O2 sensor and his readings went back to normal. (Although we will never know what the true AFR was on the 11.3 run...)

The owner always admitted he "just wants to drive the truck" and thus, often takes shortcuts or band-aid fixes when installing new parts or doing repairs.

I always try to follow the instructions to the letter, especially any electrical wiring. Things like using solder, heat shrink tubing, testing for adequate grounds, verifying voltage on a DVM, etc. Several times the owner and I have attempted to tune the truck, only to be set back by unforseen wiring problems causing all types of electric gremlins: DataMaster disconnecting at WOT every other time (faulty alky wiring in the fuse panel), a truck that died and left us stranded (more than once), bad WBO2 readings (once a bad sensor, twice bad wiring), hoses coming loose, etc.

Some guys think it's "lame" to do things "by the book" and like to take short cuts, but given the difficulty of building/maintaining a fast modified SyTy, I feel that doing things by the book is actually the least amount of work, in the long run. -- For nearly every modification/repair! When you double or triple check something, or make reference notes on the install, you can be sure it's done right and likely to remain so in the future. This is another reason I advocate running as many stock parts as possible. It's likely the factory designers are better engineers than you are, so why reinvent the wheel? When I hear of guys having problems with aftermarket electric fan conversions (for instance), I wonder why they wouldn't just run the stock fan for free and avoid all problems to begin with? Isn't the real goal a truck that throws you back in the seat, not one that keeps you under the hood? (OK, rant off.)

The bottom line is that short cuts and quick-fixes don't usually pay off, and often they come back to haunt you months or years later. If we had been able to spend 100% of our "tuning time" actually doing tuning (instead of making repairs), maybe the truck would already be in the 10s...

Sunday's Goal: Make a Max Effort High-Boost Tune on VP C-16 Race Gas - And try to get into the 10's on the DataMaster Quarter Mile Calculator

He bought ~$200 worth of the 2nd finest leaded racing gasoline available to turbo racers: VP Racing Fuels "C-16". (Motor Octane: 117) He asked me to help him crank the PT67GTQ turbo up to it's max and make his $6000 race motor run as strongly as we could make it. He was willing to accept the risk of an engine failure; after all, we're asking for 10 seconds from a 4.3 V6.

Initial Testing on 93 Octane/Alky

We started out by recording the current condition of the truck on DataMaster. He said it had been running good all spring with the same tune from when it ran 11.39 @ 116. The first time he hit it, when the converter locked up in 3rd gear, I could tell this truck was seriously hauling ass!! Strangely enough, it felt faster than when I last tuned it. No wonder it went 11.3. Here's a look at the DataMaster file from a rolling 2nd & 3rd gear run:

Right away I noticed the Wideband data appeared incredibly lean (14.3:1 at WOT). However the actual PLX wideband display itself was reading somewhere in the low 12:1 range. I chalked it up to his bad wiring, since we had a similar problem when the Wideband ALDL patch & ECM wiring were first connected. If you don't follow the instructions for the PLX wideband during installation, the output data can be off a significant amount. Remember what I mentioned earlier about not taking shortcuts?

The important thing is that the knock was low (peak KR: 3*) and the truck felt really strong. One weird thing I noticed was that the Boost (pink line) seems to spike and then taper off the longer he stayed in it... (More on that later.)

Here's another run from the 93 octane/alky, a 50-100 MPH 3rd gear romp:

I didn't notice it at the time - but did you notice the peak boost was only 17.7 now? We hadn't even touched the boost controller yet. The AFR still looks "lean" on this one but not as lean as the last run. But of course we can't trust that data due to faulty wiring. At least the knock was mostly flat-line zero except a 2.8* spike on spoolup.

Problems Draining the 93 Octane - Bitten once again by unnecessary aftermarket modifications!

We started out trying to drain the remaining 6 gallons of 93 octane from the tank, to ensure the 117 Motor Octane C-16 race gas wouldn't be diluted. After spending 30 minutes gathering gas cans, a correct -4 AN fuel hose to tap the fuel rail, and a drain hose to get it into the gas can, we were ultimately doomed without a way to turn on the fuel pump! Normally all stock SyTys have an empty spade terminal near the distributor (factory-installed) that can be jumpered to test/energize the fuel pump. But when this truck had the fancy $3000 custom aluminum racing radiator/Air-to-Air intercooler installed by a "professional SyTy shop", the installer hacked up the factory wire harness to connect a goofy relay for the starter and all the new electric fans they added for the new radiator and new transmission and engine oil coolers. (see engine photo) The funny thing is, the shop owner claimed the "Air to Air" intercooler would gain this truck "4 tenths". In reality, it gained 0 tenths and 0 MPH over the stock Air to Water intercooler. Obviously it also cost the truck the ability to engage the fuel pump with the engine off... But this "Tale of Woe" doesn't end here: the truck also got stuck on the side of the road (needing a tow) at least once, as a result of this nonstandard wiring.

Remember what I said in How to Get Your Stock Truck Deep in the 13's and Key Ingredients to a Fast Truck about the virtues of running stock parts and avoiding unnecessary mods?

Tuning for High Boost on C-16 Race Fuel - Part 1

We ended up driving off the 93 octane with a few more "gentle" beat runs around the block (from a roll so as to not starve the fuel pump in the slosh-prone factory Syclone fuel tank). Then we siphoned the C-16 in:

I've got to say, we were both really excited to try out this "King of Race Fuels". It smells just fantastic! But siphoning it into the tank was a real drag - I can't imagine going through all the trouble on a regular basis (like the guys without alcohol injection probably do..)

I expected the tune to change somewhat due to the different formulation of this leaded race fuel compared to our local 10+% ethanol 93 octane pump gas. To keep things simple, we planned to keep the alcohol injection activated for cooling, even though the C16 has plenty of octane to support high boost all by itself.

Given the truck's low 19* timing on the 93/alky tune, and the fact that SyTys have run up to 27* timing on C-16, I felt comfortable adding 5* timing to the F80 "PE Spark Contribution" table right off the bat. I was surprised upon the first test drive with C16, to see the PLX Wideband gauge reading in the rich 11's and 12's at part throttle, and the STerm's maxed out rich at 80. (For background on typical DataMaster values, see: Tuner's Guide to DataMaster.) I thought perhaps the C16 really was running a lot richer than the 93 octane. I started trying to tune the driveability leaner so we wouldn't foul the spark plugs before we had a chance to run the truck at WOT. I was having trouble getting it to lean out, and the owner was getting impatient because of the cost of the fuel ($13/gal). He reasoned that this C16 tune was only for the dragstrip, that he would not be cruising around town on C16, and asked me to skip the driveability tuning and just focus on WOT. He was really anxious to get to cranking up the Boost. Something still seemed off to me about the part throttle tune, but I agreed to move on to WOT tuning.

The first 3 WOT hits were OK, but I was disappointed to see peaks of 3* and 4.6* knock. You would think with C16 it should be flat 0 knock. It also seemed strange to me how the boost would spike on DataMaster and then appear to taper off again the longer he stayed in it. Here's a look at one of the first 3 WOT runs:

I was starting to feel frustrated as a tuner. It was irritating that the Wideband wiring was dysfunctional, since I normally rely upon the DataMaster WBO2 datalog values for tuning. And now it seemed like the Boost wasn't reading the same as his mechanical boost gauge! Add in the fact that the part throttle driveability was so rich, and I started having second thoughts about doing the tune and considered quitting altogether for the day. But he drove the truck from 45+ minutes away to have me tune it, and the $200 race gas was already in the tank and was such a pain to transfer in the first place! He had said he was willing to risk his motor and really wanted some results, so I continued to tune, somewhat reluctantly. If it was my truck, I would have stopped tuning and just parked it in the garage until I could figure out the faulty sensors. Then again, if it was my truck I wouldn't be tuning for high boost in the first place with DataMaster's WBO2 data not matching the Wideband...

We tried 1 or 2 more WOT hits and things seemed to be getting worse the more I tried to tune it. The drivability in particular seemed to be getting richer even though I was removing fuel. I started subtracting fuel from the main F29 Base VE table, but it seemed to barely have any effect. The driveability was getting so poor that it was reading "RICH" on the wideband under steady-state 45MPH cruise conditions! The engine was starting to buck from being so damn rich. I knew I had to take out more fuel, fast. I was taking out 10% and then 20% fuel and the wideband would barely budge. After taking out "-20%" fuel a few times, the wideband eventually responded, but then I noticed it was dreadfully lean at WOT causing massive knock!

I started to feel like maybe I just had no idea what I was doing, since the truck was responding so unusually! Then I noticed something. Here are 2 WOT runs in the same DM file; a 2nd gear hit into 3rd gear, and then a soft launch from 0 MPH - 75 MPH:

Test your "Tuning Skills"!!

Can you spot the problem?

Here is the exact same file, but I swapped out RPM and AFR Target for MAP and TPS% instead: (Hint, Hint)

Do you know what is wrong? The 2nd image shows it plain as day. Need one last hint?

Okay: I positioned the red cursor line to show the problem.

Scroll down to find out the answer!!

I noticed that the MAP sensor seemed to be reading a minimum of 99-101 KPA! I know from past tuning that normally the MAP should be in the 60-80 KPA range during cruise conditions. I also know that 100 KPA = 0 PSI in SyTy Tuning. So I started to wonder if the MAP sensor vacuum hose had come loose? But it couldn't have, because under boost, it would still read as high as 175 KPA..

We checked out the MAP sensor vacuum hose and.........


The MAP sensor vacuum hose wasn't loose, it was CRACKED and obviously leaking pressure under boost!! And running Higher-than-ever-before Boost pressures must have pushed it beyond its limit. In fact - the proof is right in the DataMaster file!

Let's take a second look at the two "Tuning Skill Test" DM runs, this time with comments:


Under high boost pressure, the MAP sensor vacuum hose was bursting open at the cracks, releasing SOME of the Boost signal, which caused the "Less than the Boost Gauge" Boost readings on DataMaster all along! And when we finally turned up the boost, the vacuum hose must have burst open completely because after that point (the one I circled above in the Green oval!), the MAP sensor never read any vacuum (it got "stuck" at ~100 KPA during all conditions except under boost!)

So that perfectly explains why it started running richer and richer at part throttle.. and why it started running leaner and leaner under boost!! When we were actually at ~75 KPA during deceleration or 80 KPA during cruise, the ECM was being told we were at "100 KPA" and delivering "100 KPA Worth of Fuel"! No wonder my part-throttle tuning changes didn't have much effect on the rich condition during cruise! And it's also no wonder the truck was running so lean at WOT. - The truck was at 22-25 PSI Boost but the ECM thought it was only 9-15 PSI! So of course it only delivered enough fuel for 9-15 PSI, not enough for the real 22-25 PSI at the engine.

All because of a basic tuneup item - engine vacuum hoses.
That is why "Check/Replace Vacuum Hoses" is listed in the Part 1: Tune Up section of How to Get Your Stock Truck Deep in the 13's (It's really a guide for ALL trucks, not just 13 second stock trucks!)

This all goes to show why Chip Tuning is often the LAST kind of "Tuning" many Syclones & Typhoons need to go fast!! Chip Tuning CAN'T come until you get the truck the truck in shape FIRST, and you can't dial it in if your measuring instruments are malfunctioning. (Or even worse, if you don't even have a wideband..... or a datalogger in the first place!)

Imagine if we didn't even have a datalogger or a laptop and we were trying to make this truck fast. We would have blown it up long before even getting to this stage, not to mention how difficult it would be to pinpoint a cracked vacuum hose as the source of our problems.

Tuning for High Boost on C-16 Race Fuel - Part 2

So obviously, after spending half an hour fabbing up a new "Upper Intake to Fuel Pressure Regulator to MAP Sensor" vacuum harness (did you ever realize how hard it is to find the perfect diameter hose that will fit snug at all ports?), we were anxious to retry the high boost tuning!!

I abandoned today's "tune" and started over from a copy I saved of the BIN he drove in with - a "Known Good State". (Saving a backup copy of your tunes when you change the original is one of the best things you can do during chip tuning!) With the Moates Ostrich real-time emulator, this was as easy as loading an MP3 onto an iPod. With the vacuum hoses fixed, the MAP sensor was reading properly again and the Boost was finally matching the boost gauge itself (within the 1-2 PSI normal DataMaster offset from boost gauge). Before long, we had the boost up around 25 PSI and look how much nicer it was running!:

This was the first run on C16 with FLAT-LINE ZERO KNOCK, even though we were running a strong 24* peak WOT timing (compared to this truck's normal 19* tune on 93/alky). The "Tune" was starting to come together, and incidentally this is when the truck started to feel like a missle blasting off in 3rd gear!! I had the digicam in my pocket but we were so focused on tuning that I forgot to get a video!

DataMaster Dyno usually puts this truck around 600 HP. But now it was reading consistently above 650 HP, with one run reading as high as 680 HP and 780 LB-FT TQ! Whether DM Dyno is accurate compared to a real dyno is up for debate, but DM Dyno is fairly consistent for our purposes. In other words, I definitely have never seen this truck put out DM Dyno numbers this high before! In fact, this is probably the fastest Syclone I have rode in!! When the 3rd gear converter Lockup hits, it jerks you back in your seat from 60-100 as hard as a stock truck does 0-60!

Tuning for High Boost on C-16 Race Fuel - Part 3
Transmission and Torque Converter Tuning

One thing I noticed about this truck (and maybe you did too, if you've been reading carefully), was that it felt the fastest when the torque converter lockup clutch (TCC) engaged in 3rd gear around 70 MPH. If I can describe it, it was like he'd nail the throttle in 2nd gear around 40 MPH, the boost would spool up and reach peak, and the truck would "get going", but shortly after the shift to 3rd gear, the TCC would lockup and then the truck would REALLY take off. Eventually it started to feel during the time at WOT in 2nd gear, I was "just waiting for 3rd gear to come", if you know what I mean.

Doesn't that seem a little strange? Where is your truck the fastest, in 1st gear or 3rd gear? I had a feeling I knew why this was happening. Once again, the DataMaster file contains the telltale evidence!:

Test your "Tuning Skills"!!

Can you figure out the problem?

Scroll down to find out the answer...

All evidence suggests to me that the

Torque Converter is TOO LOOSE!!

You hardly ever hear people talk about this, but I see it ALL the time! What happens is, guys want a "high stall converter" to spool up their big turbo upgrade. The torque converter shop gets the order and sees it's for a "V6", but what they don't realize is that a little turbo 4.3 V6 makes more torque than most BIG BLOCKS! And stall speed is directly proportional to engine torque. So put the "high stall converter" into a Syclone running high boost (torque always increases with boost!), and pretty soon the "high stall" starts to stall.... Really High!!

In the case of this Syclone, it looks like the converter was producing a WOT Stall speed right around 4800 RPM in 2nd gear! That explains why the RPM would shoot up to 4800 and then float around for a while, creating the "wishy-washy" looking RPM line on DataMaster. When a converter is at or below a stall speed, it slips away power by converting it to heat. But when a converter's lockup clutch engages, all slippage ceases and it becomes a 1:1 connection between the engine and transmission!

Are you starting to understand why the truck felt so fast in 3rd gear?? (And why the RPM line looks so much better for 3rd gear than it does in 2nd?)

This is exactly why in Key Ingredients to a Fast Truck, "For best streetability (and performance!) I recommend running the tightest converter that will still spool up your turbo." Instead of stalling out high and wasting top end power, a tighter converter will make your 2nd gear hit HARDER than 3rd gear (the way it should be!)

The converter in this truck is a Precision Industries 3 disc lockup "Vigilante" converter that was claimed to be "2800 RPM Stall". High stall converters are a confusing concept, and I plan to write an informative High Stall Converter Guide in the future. But in the meantime, you have to realize that there is more than one "stall speed" a torque converter will produce! Sure, maybe it stalls somewhere near 2800 RPM at 0 MPH.... with a certain amount of boost (that's a pretty Big Variable, wouldn't you say?) But the engine makes a LOT more torque at Peak Boost and high RPM (4000+), and that is why you see it stalling around 4800 RPM in 2nd gear. All converters have a higher "WOT Stall" compared to their "Brake Stall". But in my experience, the looser a converter is rated (Brake Stall), the bigger the difference in RPM at WOT Stall when you really crank the boost up high!

In other words...

Here's one more run, I chose this one because it's a 0-70 MPH run, so you can see how 3rd gear acted in this truck before TCC Lockup (at 70 MPH):

When I see an RPM line (red) with only a small drop at shift points, like the image above, it suggests that the converter's WOT Stall RPM is close to the shift point RPM. This truck is only dropping about 425 RPM drop on the shifts. With a 700-R4 transmission, I like to see 800-1000 RPM ideally. The torque converter doesn't have any idea what shift points the engine prefers (the powerband is determined chiefly by the duration of the camshaft), so a converter that WOT Stalls at 4800 wouldn't be a problem if you were shifting at 6000 RPM, because your RPM drop on a shift would likely land you above WOT Stall speed (which is what you want).

Now you can see why Key Ingredients to a Fast Truck stresses the importance of a well-matched combination; because most of the crucial performance parts in your truck depend upon each other's performance in order to produce the absolute best results!

One last thing: this is another example of "vehicle tuning" that doesnt involve chip tuning..

Tuning for High Boost on C-16 Race Fuel - Part 4
Pushing Things Too Far

Back to the high boost tuning; the truck has a BoostValve.com manual ball-and-spring boost controller. I was tuning the laptop from the passenger seat, and the owner was driving and tweaking things under the hood. We were turning the boost up a little at the time, but after getting the MAP sensor signal fixed and getting a clean 0.0 knock run, the owner must have got a little overzealous with the boost knob (or perhaps didn't realize how sensitive the adjustment gets at high boost) because we were at 25 PSI on one run, but on the next run the boost gauge nearly hit 30 PSI! DataMaster showed a spike of 27.2 PSI, and DM on this truck is 1-2 PSI lower than the actual gauge reading. The knock was horrifying at 13.0* peak!:

As soon as the boost spiked, I could tell something was wrong and the truck felt down on power, too. (Some people think that if the boost dangerously spikes high, it would make the truck REALLY fast for a brief instant, but that's not usually true.) When we slowed down, the engine was idling at 2000 RPM. The owner felt that something had blown off causing a vacuum leak. The tuning had to come to an end. After a day of diagnosis, he determined it was a lower intake gasket that blew out.

If you look carefully, you can see right where the gasket blew out on the DataMaster image above: on the 1-2 shift!! The pink line shoots up like a rocket and makes an uncharacteristic abrupt 90* change downwards, slowly dissipating to a flat line.

We were really lucky!! Several things led up to this dangerous situation which could have resulted in engine failure...

Here's a list so you can learn from our mistakes!

  • The obvious problem was getting too aggressive with the boost controller! As the spring tightens in the BoostValve (especially with the High Pressure Spring necessary for these type of boost levels), the adjustment gets more sensitive. The owner said he gave it something like 2 full turns in, after we were at 25 PSI! At that point we should have been increasing boost more slowly, like a quarter or half-turn at a time.
  • The high price of C16 and the hassle of siphoning race gas put us in a time crunch, making the pressure high to get quick results! But safe tuning can't be rushed.
  • Faulty instruments! If I had known this truck's Wideband was reading faulty in the DataMaster log compared to the gauge reading, I would have suggested the owner repair the wiring before we went ahead with High Boost Tuning. It's so important to know your WOT AFRs.
  • Failure to keep the engine's basic tuneup in check. By that I mean the heavily cracked vacuum harness going to the MAP sensor. Don't forget my Tune Up list for any truck, listed in: How to Get Your Stock Truck Deep in the 13's
  • Not Datalogging Frequently Enough! - Like I say in the Scan Tool section of "Deep in the 13's", "You can't master the tune on your truck if you don't know anything about it!" In this case, if the owner had monitored recently on DataMaster, he might have noticed that the Boost PSI on DataMaster was not matching the boost gauge closely enough, which led us to the cracked MAP sensor vacuum hose.

Once the lower intake gasket gets fixed, we'll try tuning it again on C16 and see if we can't get it into the 10's on the DataMaster Quarter Mile Calculator! Stay tuned...

Thanks to the owner of Syclone #587 for permission to write about his example.

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2008-2009 Josh Straub Home | Syclone | Turbo Grand Prix | Computing | Contact
  Last Modified: Wednesday, 25-Nov-2009 01:25:32 UTC