MPFI manifold, MS Q's

Discussion in 'High Tech for Old Iron' started by tt_skylark, Aug 9, 2011.

  1. pmuller9

    pmuller9 Well-Known Member

    I'm not sure how much additional information on plenum volumes would apply in your situation.

    Consider that at WOT all volume between the supercharger and the engine which includes the intercooler, contributes to the plenum volume.
    Also since you are port injected the considerations for wet manifold design disappear.

    The one change I noticed from our Racepak Data is when we switched from a single plane to a manifold similar to yours with lots of volume,
    at boost levels above 25 lbs, the engine did not shut down the instant the throttle plate closed.

    I think you should weld it up and see how it responds. It looks Great!

    Paul
     

    Attached Files:

    Last edited: Aug 23, 2011
  2. sean Buick 76

    sean Buick 76 Buick Nut

    Is this car for drag racing only or some street use?

    The bottom line is that the "slightly boosted air" in the manifold under part throttle helps reduce the "lag" when the throttle is floored. Because the manifold contains a volume of boosted air it is easier to get the boost to rise quickly. Gale Banks calls this "gulp capacity". For an all out race car this is of little concern, for a street car this is very important!:beers2: At WOT once at full boost there is not need for much plenum volume, it is just the transition from low boost to high boost that requires a larger plemun.

    It looks about right to me for the plenum size. I would not go any smaller, the volume will help keep your boost rise quickly!:3gears:

    Tell us more about the combo:

    What rod length?

    What compression?

    What size turbos?

    Did you sort out the "gaskets to go" head gaskets, i know you were having an issue there... Mine are still in the box, so I am not able to help you there...
     
  3. tt_skylark

    tt_skylark Well-Known Member

    The rods are forged carrillo, they are about .100 longer than stock, I narrowed them to fit the buick crank and had to clearance them just a bit for the cam them with the custom diamond pistons I had it all balanced.
    Compression comes out at 8.9-1, it should be ok with the intercooler setup and meth injection.
    The turbos are a t04e journal bearing .50a/r comp and .63 turbine, fairly inexpensive. It will leave room for upgrades later, having to be budget minded......

    I started with one of Burtons kits....... lets just say that didn't work out, it was scrapped and did my own fab work.
    Serves me right:Dou:

    the burton kit will be for sale on here very soon, for cheap!
     
  4. tt_skylark

    tt_skylark Well-Known Member

    The gaskets to go is still waiting to be sorted, they want me to send them back and let them have another try at it.....
    The bores are not even the same and all are too small and hang into the cylinder!:rant:
     
  5. sean Buick 76

    sean Buick 76 Buick Nut

    I guess I need to send mine back as they are still in the box... What overbore are yours?
     
  6. tt_skylark

    tt_skylark Well-Known Member

    They were supposed to be .040 over, they range from .012 to .035. I spoke with a guy from the company and he told me that I may be able to just open them up a bit.... My response was that I did not pay the money for these gaskets to have to modify them to work as ordered.
     
  7. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    I'm kinda late to the game so I may be repeating someone.

    The Grand National cam sensor should drop right in to the 350 and looks fairly clean. Removing/grinding off part of the reluctor works too. VERY interesting on the cadillac distributors, I'll defiantely take a look at one of those next time I see one in a junkyard.

    On the crank trigger, I'm thinking if you are going sequential you might as well go with a higher resolution trigger wheel, a 36-1 or more just to be sure you nail the timing relative to where the crankshaft is. The cam sensor is more for injector timing phasing. The rule I've heard on that one is lock your injectors to stop spraying when the intake valve closes, so as the duty cycle increases they are spraying earlier but stopping at the same time relative to the intake valve. Back to the trigger wheel, have you seen my thread on going distributorless? Some of what I've done may apply pretty easily to the 350.
     
  8. tt_skylark

    tt_skylark Well-Known Member

    I have been fallowing your distributor less post as well, I am running into packaging issues with the coil packs.
    I was hoping to mount them off the un-used threaded holes by the exhaust ports but I don't have enough room with the turbo setup.... also the heat may be too much for them.
    I am weighing the pro's and con's of coil packs and sequential FI vs using my MSD dist and doing bank firing of the injectors, from my research so far my gains will be minimal with the sequential FI and I can still retard the timing with the MS3.
    As always any input is welcome, as I am always learning!!!:TU:
     
  9. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    Looking at your wild intake, what keeps you from mounting the coil packs on the firewall and running the wires through the air gap between the intake and lifter valley? The wires wouldn't be much longer than a stock system, it's something I'd try with a quality set of wires and a good set of coils.

    Kinda like I did with my injector wires only you have more room under there. The beauty of not having a distributor in the back there.

    [​IMG]


    Mounting the coils in a similar place to where I have my relay board mounted on the firewall.
    [​IMG]
     
  10. TheSilverBuick

    TheSilverBuick In the Middle of No Where


    Also it's not like you can't upgrade later, it's a minimal expense to set it up one way then convert later versus setting it up from the start. I'm not positive, but I think MS3 with sequential injection can balance the injectors, meaning if you have a cylinder running lean because of head/intake design you can richen just that cylinder. Which in some cases might be worth a bit. You need to be able to read the AFR's on individual cylinders though, or be an awesome plug reader.
     
  11. pmuller9

    pmuller9 Well-Known Member

    If you don't already have an ignition box with a coil you will have to buy one.
    If you get coil packs now then you don't have the expense of the ign box and coil.

    Also when the timing is being varied over a 25 degree range it is nice not to be bothered with distributor rotor to cap phasing. I would go individual coil just for that alone.

    I also second what TheSilverBuick posted

    Paul
     
  12. TheSilverBuick

    TheSilverBuick In the Middle of No Where


    MegaSquirt doesn't need a separate ignition box, it can drive a single HEI or points coil directly. So cost the first way really is only the coil which will range between $15 and $75 depending how fancy you want to get with it. I guess you can include the cap, rotor and wires though too. In either case I call it a minimal cost. I ran about a year before I got a separate 6AL-2 box (for the 2-step rev limiter really) all the while having the MSII control timing.
     
  13. pmuller9

    pmuller9 Well-Known Member

    Thanks for the info.
    Anxious to see your engine running.
    Paul
     
  14. TheSilverBuick

    TheSilverBuick In the Middle of No Where

  15. tt_skylark

    tt_skylark Well-Known Member

    I hear ya, I will probably go with the sequential injection when I do the MS3 and I am still undecided about the coil packs. We will see what is left in the coffee can when I get to that point, I have a good dist, coil and new wires now I may leave the coil pack setup for after I have it running as I still need to to do all the tranny mount/drive shaft fab, exhaust, re rout my steering....... and whatever else pops up!

    Do you guys think its worth using a stock LS coil pack setup, or aftermarket?
    Price?

    A O2 sensor would be great for each cylinder but I think it would be cost prohibitive. Am always open to ideas.... maybe a bung with a plug and I just rotate the sensor?

    This is going to be one of my favorite daily street cars, very little track if at all:beers2:

    Thanks!
     
  16. pmuller9

    pmuller9 Well-Known Member

    There seems to be a quality issue with aftermarket coil packs.
    The recommendation is to only use GM coil packs.
    The LS2 packs are also preferred because they deliver a higher energy spark.

    One O2 sensor for each side for a total of two is sufficient.
    If a person must monitor each cylinder, using EGTs is a good method but still is not cheap.

    Paul
     
  17. sean Buick 76

    sean Buick 76 Buick Nut

    Yes, add a bung in each exhaust primary so you can add an EGT into each cylinder one at a time to monitor them. That is what I am doing. Eventually I will have all 8 feeding info to the computer...
     
  18. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    I personally think a single O2 is sufficient because if both banks aren't running the same you have bigger issues. When looking for that last few percent of HP the balancing the AFRs between cylinders is the way to go. Almost always when tuning for HP you are really tuning to the leanest cylinder if you don't want to hurt parts.
     
  19. pmuller9

    pmuller9 Well-Known Member

    We run 8 EGTs so we can monitor if anything goes wrong with any cylinder.

    We also just use one O2 but we also monitor both turbo exhaust pressures to keep an eye on the wastegates.

    Paul
     
    Last edited: Aug 25, 2011
  20. TheSilverBuick

    TheSilverBuick In the Middle of No Where

    EGT's work too. Do you ever find a wide range of variance in temps between cylinders?
     

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