Twin Turbo Skylark 350 Progress

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

  1. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA


    Wasn't trying to start an argument, just wanted to post a contrarian view to Larry M's view. If you follow this thread, then click on the link in the last post you'll see where I got the quote I copied and pasted;

    http://www.eng-tips.com/viewthread.cfm?qid=102790

    Here is the link in the last post;

    http://mototuneusa.com/super_sonic_nozzle.htm

    Good read, enjoy.




    Derek
     
  2. 8ad-f85

    8ad-f85 Well-Known Member

    Cool read, good stuff, nothing new here, but...
    I like the wider range of applied theory to this forum.
    I appreciate the intellectual and resourceful bantering :D
    I'm not arguing either, it's all about how one applies their kung-fu to any project...effective when appropriate to the situation.
    It's very difficult to post info derived from one's own or any other flowbench when the actual parts aren't present and it's still in the bench racing stage.

    The best one can do without intentionally being too specific and not actually have any data is to suggest direction based on the info given and the fact that the heads in this build won't likely have much more than raw CFM #'s...which are very limiting.
    There's kind of a fine line to how much swirl you can use and how/what you are using it for. This is an area than can have tremendous influence to the VE suggested by the sim, and more-so towards the BSFC range possibly seen from an executed example of the proposed build.
    Curious what your thoughts are on that and if you've followed any of Widmer's tech regarding?
    There's a ton of potential here with this project.

    Based on your experience with a flowbench and how you correlate that data to results, which direction or strategies might you impart to this build?
    I've given an opinion, and am offering no technical explanation for it as I'm not building this one...
    I do think the sim #'s could be hit with an intentional strategy, I'm just not confident in seeing that from what is described as a set of max ported heads done in the garage, without the benefit of said specific strategy. No offense.
     
  3. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA


    Well, the only thing known about the heads for this build is what Sean posted;

    "Will be using fully ported iron heads with oversized valve and TA roller rockers."

    Can't really give much of an opinion about the only info posted about the heads that will be used for this build. Perhaps Sean can tell us more about the heads? Flow numbers? Chamber size?

    To raise the compression perhaps the heads can be milled, get that compression up to 12:1? That is if Sean doesn't mind running race gas, if he can even get race gas?

    Sean, do you have any info for the heads you have that you wouldn't mind sharing? Are they Gessler ported or are they the Sony Seal heads you have? Any chance you can have them flowed?




    Derek
     
  4. sean Buick 76

    sean Buick 76 Buick Nut

    I am not interested in more than 10.5:1 and that is the max I could get with these spare parts I have. Not interested in stroking the engine, 355 cubes is fine and I think the big solid cam is enough for the combo.

    The head flow numbers are:

    1.92 and 1.55 valves

    INTAKE

    .050 - 35
    .100 - 62
    .200 - 118
    .300 - 177
    .400 - 218
    .500 - 249
    .600 - 258

    EXHAUST

    .050 - 28
    .100 - 54
    .200 - 104
    .300 - 147
    .400 - 177
    .500 - 179
    .600 - 180
     
  5. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    So small block Buick dump guy question.

    What rpm has someone actually achieved with the ~1.92/1.55 valve set on a 350? Not math, done in practice going down the track or such?
     
  6. 8ad-f85

    8ad-f85 Well-Known Member

    Derek, I think we are miscommunicating.
    I've never suggested a race gas type build, this is still pump gas territory with the super-swirly Buick ports and high winding potential.
    These types of projects are hugely rewarding... a slight adjustment to the old school hotrodder thinking that imposes the 'accepted limitations' that people argue about on forums. This should be a good learning experience.

    Love to see this come to fruition!
     
  7. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    I didn't mention stroking, you all ready have your rotating assembly. But now that you mention it you could stoke your crank .030" so you only need to mill .045" off of the deck instead of .060". :Brow: But if the crank is ready to run you can skip doing that.

    Having the crank heat treated would be a good idea, seeing how you're going to run a flat tappet cam. Heat treating would help protect the crank if the cam gets wiped out and sends metal through the engine. :eek2:

    Those look like decent numbers, but a little lack luster in the low lift area. Seeing how you will be barely above .500" lift having a 30* back cut on the valves would help low lift but could slow the flow on your higher lift. Seeing how you won't be hitting the higher lift range anyway, it just may be a good trade off. :Do No:

    A cam in the .650" to .700" range would help get the most out of the flow of those heads without the back cut. I wouldn't go that high with a flat tappet cam though, would be better off with a solid roller with lifts that high. Would be worth an extra 75 to 100 HP to the below guesstimation numbers, so around 475 to 550 HP with the solid roller. You could keep the duration @.050" close to the flat tappet solid cam you have, get the lift to around .675". The problem is that Mart was telling me that his .580" lift cam maxed out the cam core that is made. To get a higher lift the same cam core, a smaller base circle would have to be used, or more rocker ratio.(this is just for a reference for anyone reading this that wants more out of a similar build because I know Sean wants to use what he already has) :TU:


    With the cam you have and the flow of the heads I don't see you hitting the "super sonic nozzle" wall. I would guess around 400 on the low side and 450 on the high side of the HP range with just assembling the parts you have and running it. An extra 5% to 8% more low lift flow for having the valves back cut for a couple more HP. With 5.57 rear gears this should be plenty to get that light car in the high to mid 10s or possibly better? Fun stuff!!




    Derek
     
  8. sean Buick 76

    sean Buick 76 Buick Nut

    I did some dyno testing on a hot 350 with 1.92/1.55 valves on a 355 cube Buick 350 a long while back with a single plane custom intake, 10:1, large cam, large tube headers etc. Note there was a typo it was a 350 not a 455.

    [​IMG]

    We were not going any higher than 6500 RPM due to stock rods however with better rods there was more RPM potential in the engine if not for the rods.

    This was with the very first single plane intake that I had built and the engine used was Rob Margel's that he let me use for testing.

    [​IMG]
     
  9. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    gsjohnny has claimed to over rev to 10,000 RPM before.









    Derek
     
  10. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    Okay, 6,500rpm is pretty heady. I'd be interested to know the cam size to pull 10,000 as the engine, mathematically, seems very very under valve'd due to the narrow bore. The flow numbers seem good for the valve size, but still significantly lower than "other" similar displacement engines I know of that turn 7,500rpm. Tall narrow ports FTW!

    Carry on, I'll go back to watching as I don't have any hands on experience with the small block Buick and don't need to stir the pot that much from my arm chair :TU:
     
  11. Gary Farmer

    Gary Farmer "The Paradigm Shifter"


    He also admitted this was an 'oops' and not something done on a regular basis. lol

    Definitely wouldn't recommend this.
     
  12. Gary Farmer

    Gary Farmer "The Paradigm Shifter"


    Very impressive numbers.
     
  13. Gary Farmer

    Gary Farmer "The Paradigm Shifter"

    I know for a fact that the dyno sim I use doesn't take certain things into consideration, so the actual numbers (power, VE, etc.) should be used as a guide showing potential.

    It's also important to keep in mind that the restriction (CSA) would prove to be more restrictive if a steady flow of air is pushed through it, rather than short bursts (such as in a real engine rather than on a flow bench).

    Another reason why dented up headers aren't as restrictive as one might think (proven on a video showing little or no power loss with busted up header primaries).

    There's more science behind this, just wanted to give the 'layman's' version. The restrictions don't have enough time to do more than create a velocity increase within that area without pressure building up behind it on extended scenarios (time or distance).

    I'm sure Tony will chime in with more if he feels like giving more info away. :grin:
     
  14. Gary Farmer

    Gary Farmer "The Paradigm Shifter"


    Interestingly enough, creating a roller version using the exact same specs (valve timing events) as that cam with much higher lift and ported heads creates some pretty good power. lol
     
  15. Gary Farmer

    Gary Farmer "The Paradigm Shifter"


    Good example showing the meat of the flow existing below .500 lift (less heavily modified heads show this to be true below .400 lift).

    Taking this into consideration, lifts above .500 on symmetric lobe profiles will take more advantage of those lower lift numbers, particularly when there are still some gains above this, even as meager as they are.

    So a .550-.600 lift roller cam would suit these heads nicely, even more so with solid lifters for higher RPM.

    Of course, the more lift you can cram in there the better with heads such as these, since even more time would be spent in the meat of the flow, depending on how much time (and how high it was going to rev) it needed for max cylinder fill. :TU:
     
  16. sean Buick 76

    sean Buick 76 Buick Nut

    Gary could you do a dyno simulation on a 10.5:1 355 with these heads and the Crower stage 5 mechanical flat tappet cam? single plain intake and 750 or 850 carb?

    As a generality I feel that the optimum operating range for a close to stock Buick 350 with ported heads is 2500-6000 RPM. Any time you push up to 6500 or 7000 RPM the reliability and maintenance needs will be effected. Sure with fancy parts and high $ builds 7000 may be a reasonable goal for peak HP, but like always the idle to 3200 RPM range will be losing torque as a trade off for the high RPM power.

    This is where I come to the conclusion that turbocharging is the best way to make about 450-600 crank HP with the 350:

    1. You can use the stock bottom end and get adequate compression without milling the block or custom pistons
    2. You can use a mild cam that does not give up the bottom end torque
    3. You can extend the RPM range of the engine with properly sized turbos, my engine was peaking in HP at about 5500 RPM (Poston 114 cam) before boost and it kept rising past 6300 with boost
    4. You can make good power with 4-6 PSI and no intercooler and then it simplifies the setup not having an intercooler. 4 PSI is enough to turn a stock 350 into a healthy engine.
    5. Even without expensive head porting or alum heads you can still make 450 HP at the wheels as we proved with my old car as it had stock heads on it, 9:1 and also a Poston 114 cam, this was at 10 PSI with intercooler.

    yes we do have to dial in the tune up and ensure that #3 cylinder is getting the right amount of air and fuel and we are not sure yet if it is a carb issue, manifold issue, or if it is making so much torque the engine mount is twisting so hard on the block that the block distorts. Is MPFI the answer or can it be dialed in with the carb? We will see. Either way on low boost things are happy and long living, it is when the boost is raised that both me and the new owner of my other car are blowing out #3 head gaskets while the rest of the engine is happy. Adding exhaust temp probes in the headers to gain more data, and going to try to systematically rule things out and get things happy in all 8 cylinders. it is no issue for me to do a MPFI but this is not an option for a great many people that may be on a tight budget so I am not going to be too quick to get away from the carb.

    I set the rev limiter at 8000 RPM on this run, just to see what would break and although I thought it was a spun rod bearing initially it actually turned out to be that the timing chain broke and the bottom end of the engine looks fine, including the stock rods and pistons. The heads are in good shape too, no issues to be found.

    I did this as a test dummy to see what the stock 350 bottom end can handle, take pics of the broken rods or pistons etc for my book but the engine survived 17 PSI and 8000 RPM.

    Turn up the speakers, it sounds good!

    https://www.youtube.com/watch?v=iLwk1H4QleQ
     
  17. Gary Farmer

    Gary Farmer "The Paradigm Shifter"


    Don't sell yourself short, bro. All input is appreciated and valuable. Theory or hands on, it's all good as long as it's relevant. :)

    Even with smaller valves and narrow bore, the Buick 350 has the potential to create excellent power even if its revving capabilities are somewhat restricted vs other designs for this powerband.

    I think that in this case, the more you can cram in the cylinders at (relatively) lower RPMs the better, given its limitations. This means high flow heads and cams with gangster lifts using durations kept within its limits. It also means asymmetric lobes to maximize this effect. The math and past engineering certainly suggests this.

    At this point, techniques and tricks to maximize this effect (outside of camshaft science) with heads and headers will be critical.
     
  18. Gary Farmer

    Gary Farmer "The Paradigm Shifter"


    Sure thing, Sean. Give me some time to input the data and I'll post my findings here. I'm multitasking right now. :bglasses:
     
  19. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    Okay, one last question, what is the width and height of the intake ports?

    A lot of my interest is in comparing it to the Pontiac OHC engine I'm playing with. It has a 1.92" intake, 1.60" exhaust valve in it with a slightly wider bore at 3.875". The flow numbers I've read about (all I have until I do my own testing) sit 20-25cfm shy of the ones posted by Sean. However I only currently have about 0.465" worth of lift available to me and only ~0.438 in the engine now. I have a blank cam I may try at some point to get as much lift as possible, but that is a ways away. If I cannot achieve my HP goals with it on boost alone, I'll be working on dialing up the rpm with the boost. So watch what the Buick 350 folks are doing given the similar valve (bottle neck) size.
     
  20. Gary Farmer

    Gary Farmer "The Paradigm Shifter"

    Sean, with that cam @default (4* advance) it shows around 8:1 DCR, which may be a bit too much for common premium pump fuel and the cylinder fill it will experience.

    Installing it straight up (0*/0*) gives more leeway with 74* IVC instead of 70*.

    Retard it 2*(6* from 'default' since 4* advance is 'built' into the cam--more on this in other threads, or I can explain it again here if there's confusion) to get 76* IVC and a DCR of 7.6:1 for a more street-friendly application without race fuel.

    Power actually goes UP a few numbers, even with dropping the DCR.

    Steve has discovered this to be true with his combination when he retarded his Crower cam similarly. This would suggest the engine needs more cam (more cowbell lol). This cam would be a restriction for use with these heads, if max effort is desired.

    Input data was for a 355 CID Buick 350 with the listed Crower level 5 solid cam specs and 1.6 rr (giving .501/.514 I/E lifts), standard single plane intake flow with an 850 CFM @1.5" 4v carb, large tube headers and 10.5:1 SCR with the head flow parameters you gave.

    Results show average power figures from .006 to .050 to be 466 hp @6500 RPM with 428 ft. lbs. @5000 RPM showing between 92-97% VE at the power peaks.

    I put in the solid roller cam specs I gave earlier (even though this is a quick, simple cam design with no tweaks considered) and power jumped to 485 hp @ 6750 RPM with 436 ft. lbs. @5000 RPM.

    This was leaving all else the same, which gave about 7.37:1 DCR with a 110/108 LSA/ICL and 79* IVC.

    It showed almost 500 hp when bringing DCR back up, and well over that if you wanted to bump it to race fuel specs.

    Even if all it made was 460 hp and 420 ft. lbs., it would be super fun! :grin:
     

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