Twin Turbo Skylark 350 Progress

Discussion in 'Small Block Tech' started by sean Buick 76, Sep 25, 2012.

  1. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    The twin turbo Skylark is coming together! This car was a mess when I got it for $1500. I should have bought a $8,000 car and re-done it but hindsight is 20/20. We added new quarters, a front lip off another car, etc etc. Mark Burton put SO many hours into this car and it shows!

    I had a HUGE holdup waiting for the paint shop to paint it. Eventually I just pulled the car out and going to get it on the road first then deal with pant. The colour will be 1970 GM Shadow grey, what a nice paint it is! Leanne my better half picked it out off a car at a car show. For now the primer will do, I will make the car earn a paint job by pulling a wheely!

    Ignore the rear bumper, I have a re-chromed one to swap on.





    I will look in my fridge and see what is around for 350 recipes!<o:p></o:p>
    I came up with a nice little 355 cubic inch engine. It made 398 HP at 5600 RPM with a Poston 114 cam. I have since added better rods, better pistons, better ported heads from Sonny Seal (they ran low 11s NA with high compression), better single plane intake so it should be about 30+ HP more. I am using custom tube headers from Burton machine, T3/T4 hybrid turbos with dual 3 exhaust. The camshaft is a mild street cam (Poston 114), later I will add a custom roller cam. I will add engine pics once it is ready!

    These are custom made Hershe rods that should be safe to about 850 HP with my nice light pistons, I save about 100 grams EACH vs stock:<o:p></o:p>
    Diamond custom pistons put me at 8.5:1 They are 555 grams, that is about 150 grams lighter than stock! Times that by 8! That is a lot less stress on the crank and rods!




    The interior is almost done, it features camaro bucket seats, new black carpet, replaced the dashpad (thanks Cole), custom gauges etc. Notice the custom 6 point roll cage really matches the lines of the car! <o:p></o:p>
    I am really happy with how it turned out!
    Last edited: Sep 25, 2012
    OZGS455 and Nailhead Ronnie like this.
  2. pmuller9

    pmuller9 Well-Known Member


    As always, Great job! Nice shop too! Love all the working room.
    Gotta love all the pretty forged engine parts.
    It's almost a shame to have to run them.

    Will the cheese burger be used as a center counter weight?

    What is your horsepower goal?

    Oh yes, musn't forget. Much better header design.

  3. DauntlessV8

    DauntlessV8 Dauntless V8

    Outstanding job! What is your projected torque figures for this setup?
  4. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    I do not really have a goal for the HP, I have a goal for 10.50 in the quarter with this all steel street car.

    I project it will make about 600 HP without too much boost.... I think it is capable of hitting 750 HP at about 18 PSI however not sure I want to push it that hard. The turbos are sized so the car will make lots of boost quickly as this is a street car not a race only car. For torque, that is the key! Even at a paltry 600-650 HP the torque should be massive from about 3200 RPM on up. I expect the car to have great mid range torque alowing me to run my goals and keep the RPM under 6000.

    I know a guy with a 355 inch chevy running high tens at 12 PSI of boost using the same turbos. He is using heads that flow about the same so it gives me a good idea how it will react. He leaves the line at 2000 RPM with no trans brake and his datalogging tells him he gets from 0 PSI at the line to 12 PSI in 1.2 seconds.

    I will be leaving the line off the trans brake so I should be able to make about 6 PSI at the line.

    I am buying another set of the same rear 15X10 wheels so I can mount 27X11-15 drag radials, on the street I will run these 11" wide 31" tall BFG tires. With the 3.42 gear the RPM on the highway with the tall tires is exactly the same as the original tires and highway gear were. At the track the shorter tire will help my gearing... This was my way to get the gearing I want at the track and the RPM on the highway where I wanted it without overdrive. The 2004R is a great trans but massive torque kills them.... I stuck with the tried and true Th400 with all the goodies and a nice tight converter (2800 stall but good quality so low amount of slip)

    I will not post the engine pics till it is all pretty, but it should look a bit like this:



  5. buicksstage1

    buicksstage1 Well-Known Member

  6. yacster

    yacster Lv the gun tk the Canolis

    That's going to be sick!!!!:TU:
  7. carmantx

    carmantx Never Surrender

    Glad to see it's coming together.
  8. buicksstage1

    buicksstage1 Well-Known Member

    Sean, that thing is bagging to have a N/A 455 in it:pp once you get those turbo's and 350 installed you will be able to hang with the tuner guys:laugh:
  9. CanadianBird

    CanadianBird Silver Level contributor


    Very nice...i like where you are wanting to take this. My appreciation for the styling of that year body style has crept up on me over time. Should be a sweet n fast ride. As usual, nice work.
  10. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    Thanks! I think it will look very good once it is painted! Do you like flat hood hiding the twin turbos???

    Here is the car that inspired the paint this car is getting:



  11. Jim Blackwood

    Jim Blackwood Well-Known Member

    Yep, that's a good color. Should look real nice on the Buick.

  12. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    A Gear Vendors overdrive could help your MPG. They are suppose to handle 1,200 HP,and will bolt onto your St400,giving you overdrive in any gear,making your 3 speed a 6 speed.
  13. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Yeah,with your 3.42 gears and a gear vendor .75:1 overdrive,it would be like you had a 2.56 gear in it on the high way! Maybe even better that 20 with your tall tires may make it less than a 2.56,if you make enough low RPM torque to push it along?
  14. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    Yeah, my effective gear ratio (compared to stock tires) is a 2.73 now with my tall street tires and the 3.42 gear. So I will rev 2500 at 65 MPH which should be a good RPM to keep from lugging but not burn too much fuel. I really do not think I will bother with a gear vendors, if I want to drive fast I will rev about 3000 RPM at 75 MPH so that is not too bad. Sure I will only get about 10 MPG at 75 MPH but who cares, it will be a lot of fun with the twin turbochargers singing and dual 3" exhaust rumbling away under the rear bumper. I might add 2.5" tailpipes if I find it noisey. I am using good mufflers too so it will not be too loud! The turbos really remove a TON of noise from the exhaust as it smooths the pulses out. The X pipe further reduces noise, and I might add 2.5" tailpipes to make it even more stealth.

    Of course when it is under boost at 6000 RPM it will make some VERY loud music!!!!!

    I added this really good sound deadening material in the whole interior and that should really help make the car nice and quiet on the highway! Who cares about adding 25 pounds when you have a hot little 355??
  15. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    Look'in good Sean!

    (I can't see the pictures through the firewall at work, so just now saw them :TU: )
  16. jay3000

    jay3000 Well-Known Member

    I'm adding straight through Magnaflows in hopes that I can hear my car.. I was WOT the other day, let off the gas and got hard on the brakes at the same time and apparenty.. It cut off.. Popped in in N and started the car, but without seeing the Tach, still couldn't tell if it was running?? That's with Summit turbo mufflers..

    Good luck knowing what the hell is going on at the track beside an open header car..
  17. Nothingface5384

    Nothingface5384 Detail To Oil - Car Care

    It's actually a .78 overdrive
    i Was thinking about this for a while myself
    28in tire with 3.08s and you'll still have enough rpm to not lug an engine..pretty sure it came out to something a lil over 1700 rpms at 60mph just like a stock gn(3.42/26.6tire)
    obviously either more gear and less tire or vise versa would still be a better medium but for turbo cars you don't need steep gears.

    hi-way gears pretty much puts load on engine which in turns spools the turbos quicker,
    but all in all you want a gear ratio that puts a load on the turbos which are 3.08-3.42 range

    hopefully i explained this correctly,been a while
    its also been proven over on the turbo forums that a steeper gear(3.73) with gthe gns actually slowed down vs the 3.42 that came stock.

    in closing glad your car is nearing road worthiness. I"m looking forward to the results as mine will be fairly similar to yours .
    BTW, let me know whats the biggest downpipes you can fit for the exhaust? i was planning 3.5 dp into 3in dual but if you can somehow squeeze more let it be known :-D
    boost on bra-tha!
  18. Nothingface5384

    Nothingface5384 Detail To Oil - Car Care

    true true on the DP size i was toldto try and go 1 full size over the turbo diameter outlet..but atleast .5 over to let gasses expand
    pretty sure the t04e that i have has a 2.5 hotside outlet so 3.0 to 3.5 dp will be great for me

    The things turbos cars love the most
    shallow gears and stroke :)
    hardest thing to match in a turbo build is the stall/torque converter but im guessing 2400/2600 will be a good starting point

    ---------- Post added at 11:32 PM ---------- Previous post was at 11:22 PM ----------

    and I hear you, I geared mine to be at just under 3k(not factoring in slippage) at 75mph as I love to cruise hiway at that speed and I wasn't planing on an o/d
  19. jay3000

    jay3000 Well-Known Member

    I love my converter.. Contact JW.. I can cruise around at 1800 no problem.. Flashes at about 2900

    Just installed straight through Magnaflows offset, offset.. If you want to hear you car, I would suggest using straight pipes for starters.. Maybe a bullet race muffler..
  20. Buick#455

    Buick#455 Well-Known Member

    When are you picking it up???

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