L-n-L Performance Development

2020 Updating the shortblock, in preperation of making much more power in the near future.  Waiting on the machine shop....



7/30/2019

New Vintage USA (NVU) is now offering gauge packages for 1970-81 Trans Ams/Formulas!  Even better, I performed the initial test fitting, and suggested modifications.  Better still, I now have their FIRST set installed in my T/A!!

and how they look at night

It's  NICE to finally have gauges that I can trust!  The gauges have some cool features, like a 0-60 timer and 1/8-milee & 1/4 mile timers as well.

 Prgress chart, chassis dyno results for each step so far:

...and the torque graphs

Newest info at the top, oldest at the bottom.

March 22, 2018

It has been "one of those months!!"  I ended up installing a complete Tanks Inc. return-line style fuel system.  While leak testing and setting the initial fuel pressure, I discovered I had a leaky injector in my throttle body!  It filled the motor with gasoline!!  FAST was great about getting another complete, brand new throttle body shipped to me - but somebody entered the wrong number and I got the WRONG throttle body.  FAST covered all the shipping both ways, and got the correct throttle body shipped out the same day.  

I got the oil changed (since it was full of gasoline), got all the loose things tightened and in order, and finally took the T/A for a drive with the new EFI system.  I still have a lot of tuning to do on the VE tables (the computer is in "Learn" mode, to make that go a little quicker), but the throttle response is AWESOME!  Took it for a drive, and zero issues.  Put some more gasoline in it and brougt it home.  Parked it while I got the garage open, fired it back up, and the stupid shifter cable/linkage is LOCKED.  Not sure what the issue is, but it will be a few days before I can mess with it - oh well....

Feb 24, 2018

FAST XFI Sportsman throttle body install has started.  A bad efi fuel pump (left over from an older project) has slowed me down, but I now have a replacement.

Feb 9, 2018

I finally got the car back on the chassis dyno.  The new exhaust system is all 3", Borla ProXS mufflers, mandrel bent tailpipes, H-pipe, and some innovative flanges installed to facillitate later testing and changes. 

Now, for the lower-RPM range this motor operates, some people may think this exhaust system is overkill.  The old-school benchracers might even say something goofy like, "the motor NEEDS backpressure, it is going to lose power with a system that big."  To be fair, the improved system DID require me to richen the carburetor at full throttle.  But even with the AFR way lean, it STILL made more power than it did the old exhaust system - if your motor runs better with backpressure, then it is either poorly tuned or the camshaft design is deficient.  Here are the results:

Significant gains across the powerband, with gains increasing in proportion to the RPM.  This would be an improvement of probably two tenths of a second or more, in the quarter mile.  Here is the chart comparing how the engine performs now, to how it compared with the log exhaust manifolds and old exhaust system:

December 2017 - Headers!!!

I was going to install a set of killer large-tube headers that I got from a friend, but as time to install approached I got cold feet.  I think they are way over-kill for this motor.  So I started searching for alternatives.  I was previously contacted by a guy, and he was REALLY pleased with his Tribal Tube tri-Y headers.  He did a good job of convincing me to try a set, and was able to arrange for me to get a set on short notice.

Initially, I was NOT happy with the Tribals.  I've installed a bunch of different headers in my life, and I'm usually able to do it by myself in just a few hours - but these were NOT going in.  Searching the internet, I found someone who had the same situation.  It is the "ears" of the automatic transmission that cause the problem.  I've seen many transmission shops simply take a Sawzall and cut off those ears, when they've had to pull the tranny out of a car with headers installed, otherwise the transmission would not come out.  Luckily I have a Sawzall, and after cutting off the ears, the headers wiggled into place nicely.  

I plan on having the exhaust re-plumbed very soon, so I did not want to invest too much on hooking up these headers.  As such, I bought some cheap adapters from the local parts store, and just tacked them together with my wire-feed welding machine.  The headers DID eliminate the <2" head pipes completely, and empty directly into the 2.5" pipe.  Back to the chassis dyno, and I was PLEASANTLY surprised!!

At the HP and TQ peaks, I gained 45hp and 35tq.  But look at 4500rpm, the headers picked up 55ft-lb of torque at that point!  The powerband is significantly extended with the headers in place.  The motor also idles better and feels better everywhere.  Ignore the data at the beginning of the graph, that is not indicating any actual loss of power - rather it just shows that I was gentle on the throttle at the beginning of the dyno pull.

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July '17 - Finally got the car on the chassis dyno for some tuning & testing.  At this point it still has the same "log" exhaust manifolds that were on the old 350.  These manifolds have head pipes coming off of them that are not even a solid 2" in diameter!  From there, the pipes feed into 2.5" pipes, which then feed into 3" FlowMaster mufflers, then sloppily necked down to 2.25" tailpipes.  I was still able to make 225hp and 310tq to the wheels, but the upper rpm power dropped off much sooner than I expected.

 As you can easily see, the low-budget 455 makes significantly more power than the old 350!

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May 2017 - I've had problems accessing this website for updates, I hope I have that corrected now.  LOTS of progress:

- A/C is now cooling much better, as the trap door in the cowl was not operating properly.  With the trap door now closing, the A/C is much colder.

- All the gauges are installed and working.

- I have found the issues with the 455.  The valley pan gasket was not installed properly and had a 2" section that was not sealed.  The top and 2nd ring gaps were all 0.120"-.150"!!!!  Nearly 10x wider than they should be, and the oil ring had virtually no tension.

- New rings installed and PROPERLY gapped!

- I had a cam custom ground for this engine.  New heads were not in the budget, and the old cam/lifters were obviously working well with the existing springs, so the new cam was designed to have slightly less valve lift than the old cam (.454").  The cam ended up being 222/242 degrees @ .050", on a 116 LSA.

- My nephew, Evan Jurena, spend a few days with me, helping me finish the motor assembly, install and break-in the new motor.  Motor fired within 2 seconds of when I first hit the key - I was actually just checking to make sure the starter wires were connected correctly and did not expect it to fire!  Break-in went smooth.   Took it for a victory cruise, and it has MUCH more torque than I expected!  Even with the stock torque converter, it is a tire frying machine.

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July 7 - Picked up a 455, but it will need to be rebuilt.  I have also converted the factory A/C to 134a, and have it cooling fairly well.  Starting to acquire the missing gauges to complete the dash.  Bought a Formula steering wheel, and have it installed.

 May 18 - Installed YearOne 17" reproduction "Rally" wheels, 8" front and 9" rear.  LOTS of scrubbing on the interior, now it is actually RED!   

 May 7, 2016 - traded El Camino for Firebird

It started life as a base model Firebird, with a 350 Pontiac engine.  Supposedly it was a one-owner car, somewhere in California (it did have the smog pump on it), with a lady owner.  Due to mechanical issues it went into a shop, and health issues caused the owner to leave it there for years - around 15 years.  The owner before me found, bought it, and sent it to his cousins paint & body shop.  At the shop they started the transformation into a Trans Am, although it was just a cosmetic job.  After it was painted, it was sent to the owner's home in Houston, but he had since moved on to other projects and did not have time/motivation to finish this one.  And that is where the trade took place.

The Firebird allegedly had a bit over 49,000 original miles on it.  From the condition of the floorboard and trunk floor, I highly suspect the mileage is accurate - the floors are in amazingly great shape!