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308 V12 conversion begins

Discussion in '308/328' started by mk e, Oct 9, 2007.

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  1. mk e

    mk e F1 World Champ

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    #1451 mk e, Sep 8, 2008
    Last edited by a moderator: Sep 7, 2017
    The starter came, cute little think. Much lighter than the stock 308 starter, maybe 1/2 the weight. It looks like it will work once I put a little notch in the block and a new mounting plate for the starter. Now I need to make the flywheel.

    I made some new calibration plates for my flow bench so now I have 6, 24, 67, 131, 151, 171 cfm plates and I played with calibration equations for several hours trying to get numbers that fit the cal points well...and after all that I'm thinking what I thought was 150 could be as low as 147 but certainly no lower.....I don't know why it doesn't match my buddy's flow bench, but it doesn't and at this point I no longer care...time for bed.
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  2. smg2

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    #1452 smg2, Sep 9, 2008
    you know i was just thinking about this, the flow numbers are based on continues flow. however the engine as we all know operates very differently, if you were to modify the rig to get a reading with the valvetrain in operation I wonder what it would produce. the dynamics of flow and reversion along with velocity would be an interesting thing.

    I wonder if it would as simple as just popping the valve thru it's cycles and see what it reads? and then do it through the rpm range. probably very complex software now doing this, or heck maybe needed to interpolate the data.

    then again a continues <--- I know it's spelling it wrong, bloody computer) vacuum would not be right either. ummm distort the data by recording it, I knew all those physics courses would come back to haunt me. it seems to me that you'd need to build a rig that's a single cylinder complete with timing to the cam to get the exact data, then have a way to record the "altered" data since it will be becouse we're trying to view it :)

    I guess what I'm trying to say is, I don't think we ever see those bench numbers, at 1krpm the valve cycles in roughly 1/12th of a second, I didn't look but lets say total lift is .400" and duration of 250*. so the valve travels at 8/100ths of second, with the valve traveling 50fpm. I wonder what the valve travel does for flow disruption?

    it's been a long day, I'll let you get back to the build.
     
  3. mk e

    mk e F1 World Champ

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    #1453 mk e, Sep 9, 2008
    Everything you’re saying is right and it gets even worse because you forgot about the effect of the fuel that is beading on everything disrupting flow and also atomizing which displaces air. I am always hearing about efforts to build a flow bench with a piston to create the correct pulsitile flow, cams to interrupt flow, and injectors to deliver fuel….but I don’t expect to ever actually see one as it would be a very complicated machine and I’m not sure how much value it would actually add.

    At some point the value of simulations vs running the actual engine disappear and I think it’s well before a test machine this complicated. There are a lot of empirical relationships that have been developed between steady dry flow and engine performance that allow you to consistently predict engine output with 1%-2% which is plenty close enough for almost everyone to live with.
     
  4. mk e

    mk e F1 World Champ

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    #1454 mk e, Sep 9, 2008
    Last edited by a moderator: Sep 7, 2017
    More thinking about calibration and I realized what the heck I’ve been doing wrong…well not wrong exactly, but not the best way. There is an equation for how a flow meter acts and that is the equation I’ve been working with in various forms then I adjust the coefficients to get the line to go through the calibration points. With up to 3 calibration points the line can be made to go exactly though the calibration points but with 3 or more then 3 you end up needing to do a “best fit” and get a line that usually misses all the points but on average is as close as you can get because nothing is perfect and real measurements never match theory exactly…but what to do…..

    This morning I realized that while using the general equation would work in a perfect world or would be the best guess with no other info available, but I have other info available because I have 6 plates that I know the flow for plus zero. What I’d like is a smooth line that goes exactly though each of them….that line is a 6th order polynomial and excel is very happy to find it for me.

    When I plugged it in though I still wasn’t getting the line to go exactly though my calibration points which is impossible….then I realized that excel give 5 digits and most of them where zeros leaving only 1 or 2 actual digits to calculate with so I just didn’t have any accuracy and that is why my line I missed the calibration points. So, I divided the flow numbers by 100, which made them the same order of magnitude (decimal point in about the same place) as the pressure readings and BAM, 5 actual digits to work with and everything was fixed.

    I got this equation:
    y = 4.6536x6 - 8.7052x5 - 13.751x4 + 36.121x3 - 6.8796x2 + 1.1192x + 0.5

    This give me a correlation value R2=1 which is a perfect result and sure enough the line is smooth and goes through all the calibration points…..finally. Now understand, the problem was only 2 cfm in the worst case so in truth it wasn’t in reality a very big deal, but still. Oh, and that put the head back up to 149 so the original calibration that gave me 150 wasn’t all that bad.

    I still have no idea why I get 149 and Vic got 137…I guess I need to send him a copy of my 151 cfm plate and see what he gets on that. The calibration on my bench is nearly a perfectly straight line from 67-151 and I know Vic only uses 2 points to calibrate so can only make a straight line but I think 1 of his points is 148 so I just can’t see what is causing the difference unless the head is doing something to the flow that is bugging up my meter somehow. Vic uses a stagnation chamber on his bench so I don’t see any way the head flow could mess with his meter. Maybe I’ll try installing some kind of flow straightener and see if it changes anything.
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  5. enzo52

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    #1455 enzo52, Sep 9, 2008
    Hi, Mark

    Every time I read this thread I enjoy it.
    A question : did you check if the new starter turns in the same direction like the old one ? With the gear reduction you never know...

    Enzo52
     
  6. snj5

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    #1456 snj5, Sep 9, 2008
    Last edited: Sep 9, 2008
    Mark -
    While I did send you a PM, thought the group might like to see this as well. Over in the 206/246 section, there is a neat thread of putting a rare Dino/Stratos 4 valve 2.4 liter V-6 in a dino.

    I would imagine that this early QV head was a design predecessor for the V-8 QV, and since it is a 2.4 liter, it also has 400cc cylinders.
    Interesting to me that for a full race engine, Ferrari also chose a .360 lift, which is what WEBCAM found as the most that could be used safely long term. And, [email protected] in a 4 valve! These made up to a claimed 110 bhp/liter using Weber 44/48s.

    Any chance you'd run that cam on your computer using my current engine? :)
     
  7. mk e

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    #1457 mk e, Sep 9, 2008

    I didn't check it and until you asked I would have sworn the chevy and ferrari turn the same way....and they do. The starter is definitely set up to spin the right way....but my wimpy jumper cables don't come close to giving it the power it needs to even turn. The cables will spin the stock starter but it starts up pretty slow taking about 10-15 seconds to get to full speed.....the 3hp monster starter just hums as the cables heat up.

    Note to self…..when you replace the starter cable to make it long enough to reach to the back side of the engine make sure it’s frikin thick :)
     
  8. mk e

    mk e F1 World Champ

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    #1458 mk e, Sep 9, 2008
    Done...it wipes out the all the power up to about 3500 and adds zero to the top end. If I add race ported heads the top end comes up (still no bottom end), and the top end doesn't go as high as it does if I drop the stock 328 cams back in with the race head. My software really likes short duration cams as a rule.

    If you want more hp you'll have to ditch the carbs and open the head up some more it looks like. sorry :(
     
  9. snj5

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    #1459 snj5, Sep 9, 2008
    Thanks - that's about what I thought would happen and helps me appreciate what I have!
    I think I have more than enough power for my meager skills for the time being. :)

    Heck, I have trouble keeping up with a sailboat at 10 knots!
     
  10. mk e

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    #1460 mk e, Sep 9, 2008
    Last edited by a moderator: Sep 7, 2017
    Sean's TB thread along with my flow bench advernture got me thinking about my Tbs and the mounting them. It turns out there really isn't much room in a 60 degree V.......

    I want them mounted pointing straight into the head, but looking from the end you quickly see the TB ends up on the wrong side of the engine. Once I drop TBs on both sides you see they end up nowhere near where I'd like them.

    I think the easiest thing to do is build a simple v shaped plenum, stick a turbo on each end and call it done.


    I'm kidding!


    No, it looks like with a little machining I can slight the Tbs about 1/2" past center with a slight angle to them. That get the run pretty straight and the throttle shafts clear everything so I don't have to do anything crazy with that.

    The other option is X liking manifold so the TBs end up on opposit sides of the engine. That would let me keep axis straight in 1 plane, but causes the the perpenducular plane to be misaligned. I think this would be more trouble than it's worth.
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  11. randyleepublic

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    #1461 randyleepublic, Sep 9, 2008
    Last edited: Sep 10, 2008
    Others are thinking along the same lines. Check out the story this gentleman has written. http://mototuneusa.com/think_fast_intake_porting.htm He has taken a fresh look at how engines really work and has come up with some unexpected conclusions. Very interesting. I think that the "flow" bench of the future will have to incorporate pistons that pump along with valves that open and close. Sure, as mk e says, the formulas work, but if you have a better simulation, you might well discover constructions that provide much better performance. Motoman beat the factory teams by making his ports smaller, but that was really more a lucky guess on his part, as opposed to a result of analysis and rigorous experimentation. Still, he has broken beyond the assumptions that drive conventional wisdom.

    Have a look at this even more fundamental rethinking of the internal combustion engine. http://www.revetec.com/ This design has nothing to do with flow and everything to do with efficiency. Replacing the crankshaft with trilobe cams allows the engine designer to make much more efficient use of the impulse generated by fuel combustion. Plus if the solid rod design would allow a practical ceramic engine, wow!
     
  12. Newman

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    #1462 Newman, Sep 10, 2008
    Why not have the t-bodies laying horizontal on a long runner that puts them above the valve covers? Use a 2 piece manifold on each bank where you can use a rubber coupler near the head as a location to disconnect the main runner and t-body for valve cover removal. This way lid clearance is good and you have the benefit of a long runner. I dont know how critical you need to be farting around with slight angle changes to achieve the ultimate for that extra 3HP when the long runner will give you some room and torque? Just a thought.
     
  13. 246tasman

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    #1463 246tasman, Sep 10, 2008
    I agree.
    Jenvey UK suggest a length of 350mm inlet tract (valve head to trumpet face) for a 9000rpm motor, and say longer is better than shorter if you have to choose. They also suggest a minimum of 200mm valve head to butterfly at these rpm. What lengths can you achieve?
    Also, what angle gives you a straight tract?
     
  14. Hans

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    #1464 Hans, Sep 10, 2008
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    You mean something like this, but then with individual throttle bodies? (599 and Zonda engine)
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  15. Newman

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    #1465 Newman, Sep 10, 2008
    BINGO, even the 456 and 550 uses this setup. Cant go wrong using longer runners.
     
  16. 246tasman

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    #1466 246tasman, Sep 10, 2008
    And it looks like Mark might achieve this with straight inlet tracts too..
     
  17. Spasso

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    #1467 Spasso, Sep 10, 2008
    Plus bit looks great.
    The long runners will enhance the power band and reduce TB crowding. Throttle linkage designs should be easier and tuning adjustments should be more flexible
     
  18. mk e

    mk e F1 World Champ

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    #1468 mk e, Sep 10, 2008
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    You guys talking torque do know this engine will easily make over 300 ft-lb of torque at idle, about 550 ft-lbs peak torque, and this is a 3000 lb sports car not a 5000 lb sedan right ;)

    Any way, TBs over the valve covers is not really an option I don't think. If you look at the pic of where the engine sits relative to the fire wall it will be extremely tight if I try to stuff them in there.

    I cut a 300mm rod (not 350mm because I didn't read carfully enough first), stuffed a scale in the port to give me an idea of where straight was and had a look at things.

    If I keep everything on it's own side I can easily make 300mm length under the deck lid but I don't know about 350, maybe. The TBs get really really tight if I try to keep the port as straight as possible

    If I build an X manifold 350mm would be easy to fit. It is a harder intake to build because it would have to be 1 piece and it's harder to get it top flow I think.

    I'll have to think about it a bit. The X manifold certainly has some merit.
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  19. mk e

    mk e F1 World Champ

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    #1469 mk e, Sep 10, 2008
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    My new throw-out bearing came today, tiny little thing.

    I had a thought that I might be able to put the oil seal right into the bearing housing, but now that I see it there is no way that's happening....the assembly just got .3" longer than I'd hoped.....maybe there's still a way.....and that contact face that is pressed into the bearing sure looks about 1/8" longer than it needs to be :)
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  20. Newman

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    #1470 Newman, Sep 10, 2008
    Remove the aluminum panel ahead of the engine and the one under the back window, it adds room and only US spec cars with loads of smog equipment need the heat shields. It might make your manifold options easier.
     
  21. Pantera

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    #1471 Pantera, Sep 10, 2008
    If only there was V12 swaps.

    Id love to toss that motor in my camaro but I can't :(
     
  22. randyleepublic

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    #1472 randyleepublic, Sep 10, 2008
    OK here's the wack idea: bring all twelve runners back! Suspend all twelve tbs over the rear valve cover. Doable? I doubt it. But, you have to admit it would look rad.

    As for flow, I think that it's at least conceivable that the runners could be tuned to equalize flow between the ones that curve for the back bank and the ones that run straighter to the front bank.

    Picture it, you open the hatch - there they are! All twelve throttle bores, dramatically staggered high and low, right there in your face. Ohhh! Ahhh! V8, did you say? Can you count!?

    :D

    Just saying...
     
  23. mk e

    mk e F1 World Champ

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    #1473 mk e, Sep 10, 2008
    The 400 and 412 cars came with a GM automatic trans, you just need to make motor mounts.
     
  24. mk e

    mk e F1 World Champ

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    #1474 mk e, Sep 10, 2008
    I don't know...it would look good but I'm big on symmetry as a rule.
     
  25. PSk

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    #1475 PSk, Sep 10, 2008
    This would be like a Alfa 164 engine ... but with double the number of runners.
    Pete
     
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