Project - 86 Omni GLH Turbo

[GLHS60]

What's the reasoning behind running the pistons .30-.40 out of the hole ?

Hopefully Ken wont mind me inserting my 2 cents here. In order to promote more complete combustion and reduce detonation, experienced engine builders strive to have the clearance between the piston and cylinder head as tight as possible at TDC. This is known as the squish area, and tight squish squeezes the air/fuel mixture out of this area as the piston reaches TDC in a turbulent manner enhancing combustion. As our head gaskets are approx. .068" thick compressed its necessary to have the piston "proud" or above the block to create a favorable squish zone. From here its mathematics, from the compressed gasket thickness, of say .068" subtract the desired squish distance, say .028" and you get .040," "proud" or out of the hole. These numbers are just my examples, but hopefully can shed some light on your question.

Thanks
Randy

[5DIGITS]

Hopefully Ken wont mind me inserting my 2 cents here. In order to promote more complete combustion and reduce detonation, experienced engine builders strive to have the clearance between the piston and cylinder head as tight as possible at TDC. This is known as the squish area, and tight squish squeezes the air/fuel mixture out of this area as the piston reaches TDC in a turbulent manner enhancing combustion. As our head gaskets are approx. .068" thick compressed its necessary to have the piston "proud" or above the block to create a favorable squish zone. From here its mathematics, from the compressed gasket thickness, of say .068" subtract the desired squish distance, say .028" and you get .040," "proud" or out of the hole. These numbers are just my examples, but hopefully can shed some light on your question.
Thanks
Randy

Well said and thank you.

[1984rampage]

Hopefully Ken wont mind me inserting my 2 cents here. In order to promote more complete combustion and reduce detonation, experienced engine builders strive to have the clearance between the piston and cylinder head as tight as possible at TDC. This is known as the squish area, and tight squish squeezes the air/fuel mixture out of this area as the piston reaches TDC in a turbulent manner enhancing combustion. As our head gaskets are approx. .068" thick compressed its necessary to have the piston "proud" or above the block to create a favorable squish zone. From here its mathematics, from the compressed gasket thickness, of say .068" subtract the desired squish distance, say .028" and you get .040," "proud" or out of the hole. These numbers are just my examples, but hopefully can shed some light on your question.

Thanks
Randy

Awesome, thanks for the information.

Would you have any links or recommended books where I can find all of this and other useful information ?

[GLHS60]

This is a pretty good read, although it promotes Hypereutectic pistons, which are often too brittle for our engines.

Thanks
Randy

http://www.beckracing.com/page05.htm

- - - Updated - - -

Well said and thank you.

Wow, I sure appreciate the kind words!!!

Thanks
Randy

[5DIGITS]

It's been a while since I've provided any updates on this project and I assure you there's been many challenges to over-come since my last update.

With this..

The relatively stock DC arrangement that achieved a 13.5 @ 106 under 14psi was removed due to a failed guide, in the head.
The engine, as planned, has been significantly updated with the following so the ultimate goal can be reached.

Single ball bearing turbo - this is important due to a prior test with a dual ball bearing unit.
The dual ball bearing units typically use a dual turbine seal on the compressor side, due to the drag generated by the conventional compressor carbon compressor seals.
This did not fair well in a turbo-I arrangement as the compressor realizes full engine vacuum and significant oil was pulled across the turbine seals into the compressor housing.
So far, pull over has been minimized on the SBB unit and is currently being managed.

The turbo is a T3/T4 hybrid arrangement with a 50trim on the compressor side along with a S-II on the turbine side.
Additionally and to spare the existing 525 trans, the boost is limited until higher RPM in the software and has been successful so far in keeping things in one piece.

The +20 injectors have been replaced by +40's and the 2bar MAP is now a 2.5bar, to support the 18psi target.
Spark and fuel calibration are near complete and the car has proven to be measurably quicker/faster the the previous arrangement.
Understanding that the turbos ability to 'pull' air is less efficient than pushing it, a 4.7L H.O. 70mm was adopted in exchange for its upstream 46mm predecessor.
This came with significant challenges due to packaging and a reverse rotation on the throttle - it required some creative 'go-arounds' to make it work.
In short and as I continue to dial the car in, its ridiculous how responsive this package is to the latest round of changes.
To estimate what the updated MPH may be would have me placing it near 115mph, in the quarter mile, for this first go around but this wont be realized or validated until I get to the track.
None the less, here's how it appears from the front and how tightly packaged the hardware is from the rear pic of the engine.




I'll provide updates as they occur.

Thanks

[rx2mazda]

sweet project!

[2.216VTurbo]

Yeah, well I must have been living under a rock in January because I missed the thread altogether! It's good news to me when I hear that the next generation wants to get involved I can't seem to get my 13 year old excited about our father-son project, his 89 GTC Skatepark and Xbox online just has way more appeal to him than building his first car together.

I also find it amusing how most of us take the 'easy route' on builds with big intercoolers, extra valves, nitrous or whatever makes more power yet the big brain guys like yourself Ken do it the 'nostalgic' way because you can

[ajakeski]

I had the oil in turbo issue with the new engine in my GLH this spring. The turbo was a generic rebuilt unit with a TII type dynamic seal. I didn't discover that until I pulled the turbo off and tore it down to rebuild it, assuming the first rebuild was bad.
I replaced the dynamic seal with a carbon seal and all was good.

I may have to steal your ideas and apply them to my GLH.

What calibration are you using?

[5DIGITS]

I had the oil in thurbo issue with the new engine in my GLH this spring. The turbo was a generic rebuilt unit with a TII type dynamic seal. I didn't discover that until I pulled the turbo off and tore it down to rebuild it, assuming the first rebuild was bad.
I replaced the dynamic seal with a carbon seal and all was good.

I may have to steal your ideas and apply them to my GLH.

What calibration are you using?

The first turbo is such a great piece, I'm trying to generate a design change that still supports the use of the upstream TB.
I write my own software and calibrations, specific for each application.

[5DIGITS]

Yeah, well I must have been living under a rock in January because I missed the thread altogether! It's good news to me when I hear that the next generation wants to get involved I can't seem to get my 13 year old excited about our father-son project, his 89 GTC Skatepark and Xbox online just has way more appeal to him than building his first car together.

I also find it amusing how most of us take the 'easy route' on builds with big intercoolers, extra valves, nitrous or whatever makes more power yet the big brain guys like yourself Ken do it the 'nostalgic' way because you can

The truth is, anyone can and there's no big brain needed.

To date, this project has failed more than it has succeeded.
It has been plagued with module, electrical and mechanical issues that have truly tried my patience.

For example:
It has destroyed two soft hardened comp cam S60 cams (which took out a rod bearing causing a complete rebuild)
Suffered a logic module failure due to electrical issues
Caused calibration frustration due to drifted MAP sensor voltages caused by a functional but faulty MAP sensor
Required fabrication rework due to clearance issues of the AIS/TPS and the brake master cylinder.

With all the software tools available, the cal's can be done numerous ways and done properly for anyone willing to do it right.
Then its simply left to generating a well mated hardware package that will run well when the previous calibration effort is applied.
I have never been a advocate of huge intercoolers, enormous turbos and the "bigger is better" approach.
Because if a car can run mid 11's at nearly 120MPH with less than 20psi on stock appearing components, why does another car run nearly the same ET/MPH with 28+psi, a header, a condenser sized intercooler and a turbo that belongs on the wing of a 747?
Long ago I wrote a simple spread sheet calculator that I have used ever since and keeps me in check.
Its approach considers the NA HP of an engine, introduces boost, estimates the boosted HP and engines efficiency for every pound of boost so that a second field can be populated for an increase in boost, changes in hardware and the resulting measured HP to solely indicate if efficiency has been gained or lost. This is how a nearly 10psi difference between the above example screams of efficiency loss somewhere in the project.
At that point, one should be asking WTH and trying to determine why the efficiency is so bad.
As the weak areas are identified and new HP results are obtained, then boost can be reduced and eventually the same power is made with far less.
It simply helps promote a 'complete system' approach rather than force feeding a digestive system that can't pass waste.

[ajakeski]

Is your cal based on 1986 or 1987 TI? I have been wanting to see if the 1987 TI cal provides any benefit over the 1986 cal or if they are the same.

[5DIGITS]

Is your cal based on 1986 or 1987 TI? I have been wanting to see if the 1987 TI cal provides any benefit over the 1986 cal or if they are the same.

1987 T-II (only for the stepper AIS)
The previous system still used the DC two-wire and that was 1987 T-I.
There are improvements in the 87 logic and I would suggest it.

[5DIGITS]

The inlet revision has been mocked up for packaging and testing.
This was necessary to provide added clearance between the AIS/TPS sensor and the master cylinder.

[contraption22]

Ken, what do you feel is a safe quench clearance for a street/strip car with forged pistons?

[mopar-tech]

I have never been a advocate of huge intercoolers, enormous turbos and the "bigger is better" approach.

It all depends on the skill level of the owner of the vehicle.

While it is easy to state that "you need to look at the engine as a complete package" in my experience few people can or do.

In such cases those folks are well suited to upgrades like intercoolers (maximizing air density in the port,) lowered backpressure with improved turbo-chargers housings, etc.

Do you know how many people I have tried to explain peak torque via spark advance on available octane fuel and been given blank looks? If you are already at peak torque via advance 5 more degrees isn't better still.

[5DIGITS]

Ken, what do you feel is a safe quench clearance for a street/strip car with forged pistons?

There's a few variables that should be considered (i.e. octane, boost level, water injection, etc..) but I would not run tighter than .025", at a minimum.

[5DIGITS]

It all depends on the skill level of the owner of the vehicle.

While it is easy to state that "you need to look at the engine as a complete package" in my experience few people can or do.
In such cases those folks are well suited to upgrades like intercoolers (maximizing air density in the port,) lowered backpressure with improved turbo-chargers housings, etc.

...and that's frustrating.
Gearing, tire size, peak torque RPM, Peak power RPM, .... it all needs to work for a car to work well.

On a lighter note:
I took the Omni out tonight to run some tests and find out where its at.
The new inlet system is installed and has corrected the interference issues with the master cylinder.
EGT's look decent and A/F is a bit thick but workable.
It has a 50/50 mix of premium and Cam2 100 Octane, the car is accepting good spark advance, while running the pistons above the deck.

With this said, I end up next to a modified Shelby Super Snake and after the first light and run well into 4th gear, he would not give me any future opportunity for the remainder of our drive.
The little red roller skate is showing promise for being a Turbo-I configuration with a DC Interheater - its getting there.

[Shadow]

Very Cool nostalgic goal! Frustration level is understandable when you set out with a specific goal like this because in the back of your mind you are fighting off the "there are so many ways I could do this easier" voices. (but that would defeat the whole purpose)

I think what is really Neat about this, is that it highlights the fact that everyone can have a goal and it doesn't have to be the "same goal" or even share anything in common with anyone else's goal.

It also shows that "efficiency" is in the eye of the beholder!

[5DIGITS]

Very Cool nostalgic goal! Frustration level is understandable when you set out with a specific goal like this because in the back of your mind you are fighting off the "there are so many ways I could do this easier" voices. (but that would defeat the whole purpose)
I think what is really Neat about this, is that it highlights the fact that everyone can have a goal and it doesn't have to be the "same goal" or even share anything in common with anyone else's goal.
It also shows that "efficiency" is in the eye of the beholder!

Thanks Shadow.

The frustration was in regards to MoparTech's quote but with anything worth while, there will be challenges.
The only goal with this project has been to make it work and work well, which I believe is everyone's goal.
Although, efficiency can be measured and isn't a matter of opinion, including mine.

[GLHS60]

I really like the draw through turbo while changing gears under boost

Very good build Ken!!

Thanks
Randy