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Why not boost the ETA?

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    #16
    put a 323 head on it. I has one.

    I was up above it, Now I'm down in it ~ Entropy - A Build thread.
    @Zakspeed_US

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      #17
      I'll elaborate; Think of it like this, with N/A engine you are sucking air in, so the restriction is a real problem, and polishing the intake will help smooth things out, with forced induction you are pushing it in, kind of like sucking on a straw VS sucking on the open end of an air compressor hose, so the difference is less as a percentage of total flow, and you can always turn the boost up a little :p.

      If you want insaine horsepower power you would be best off with an i head, but the e head might actually make a better DD because of the low end torque, you could get the turbo to spool up sooner, smaller turbo that comes in sooner.

      The real question is what are you going to do with the car?

      Originally posted by ForcedFirebird View Post
      Yes, I understand the flow difference between the i and e heads.

      BUT the same goes for my other car (as explained above), yet the iron heads with boost will still do quite well (~12-13sec 1/4's).

      When you have a lesser flowing head and you apply boost, you have lesser issues with port volume, velocity, and definatly making power, than you would talking N/A.

      Does anybody here (or can link me to threads with) flow data on the various stock heads? Perhaps someone maybe even went as far as testing with/without manifolds as well?

      EDIT: I posted before you pic insert of the dyno graph ;)

      Anybody have numbers on the e head and boost?

      This place is like catholic school, 2/3 of the students smoke weed on a daily basis, but the faculty seems to convince the outside world that drugs are just in the other schools, the resident pot dealer thinks he's cool because he has the originality to call anyone he doesn't like a homosexual, and most of the little children follow him like sheep, then there's the few with brains, you hardly ever hear from them, perhaps don't even know they exist, but they get all the sh!t done.

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        #18
        John-

        I forgot to ask what year your firebird is, I have an '87 Trans Am GTA in the barn waiting for a brightening :D

        This place is like catholic school, 2/3 of the students smoke weed on a daily basis, but the faculty seems to convince the outside world that drugs are just in the other schools, the resident pot dealer thinks he's cool because he has the originality to call anyone he doesn't like a homosexual, and most of the little children follow him like sheep, then there's the few with brains, you hardly ever hear from them, perhaps don't even know they exist, but they get all the sh!t done.

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          #19
          Right now the plans for the car are open. I'm gathering parts to do the GM OBD1 ECM swap to get a hold of the engine management (I started a thread here about it). After which, I really need to do the timing belt and figured I may swap the head while I'm at it. Then once the Firebird is done, maybe some boost, dunno yet.

          Firt item on my list is to get my F150 back on the road. Used motor is going to set me back $1500 or so, and need at least two vehicles running (have four kids, soccer etc). Once that's finished, the 30 can go under the knife.

          The 30 needs some TLC now. It still only has just over 80k miles, but the wife banged up the front fender, then shortly after I bought a new one (ebay for $100 aftermarket :D), a drunk driver side swiped it and fubared the other side. Thing was mint when I got it :(

          Firebird is a 1990, you can see my vehicles here...



          Need to update the pics soon haha....
          john@m20guru.com
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            #20
            Have you looked at www.car-part.com for an engine? $1500 sounds like a high price for a used engine unless it is installed.

            This place is like catholic school, 2/3 of the students smoke weed on a daily basis, but the faculty seems to convince the outside world that drugs are just in the other schools, the resident pot dealer thinks he's cool because he has the originality to call anyone he doesn't like a homosexual, and most of the little children follow him like sheep, then there's the few with brains, you hardly ever hear from them, perhaps don't even know they exist, but they get all the sh!t done.

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              #21
              Originally posted by napabavarian View Post
              Have you looked at www.car-part.com for an engine? $1500 sounds like a high price for a used engine unless it is installed.
              HAHA, i might as well have stock in that site

              I buy at least 6 or 7 engines a year for my shop ;)

              It's just the Triton motor, they are a 100,000 mile tune up, so when they have 60-70k on them, they aren't cheap. I got 200,000 miles out of it constantly being overloaded and I'm not easy on it, but it overheated when my dad was driving it (I was in the car behind being towed) and he didn't notice until it was too late. I could change the head gaskets, but it's a pain with the OHC's, and the bottom still has 200k. Not to mention there ws a few cups of coolant in the oil, I'm not going to do all that work and have it go again. Crate motors are about $5k, and I just can't replace the truck as cheap as I can swap the motor, the rest of it is in good shape.
              john@m20guru.com
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                #22
                Any progress on your E30?

                I have a line on a blown eta motor (timing belt victim) and will soon have a good m20b25 head out of an e34. Depending on the shape of the bottom end of the eta, I may have the makings of a decent project.

                MS + Supercharger should make for a fun car, even in an e34.

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                  #23
                  I run 7psi on my 10.5:1 m42.

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                    #24
                    Originally posted by autophile View Post
                    Any progress on your E30?

                    I have a line on a blown eta motor (timing belt victim) and will soon have a good m20b25 head out of an e34. Depending on the shape of the bottom end of the eta, I may have the makings of a decent project.

                    MS + Supercharger should make for a fun car, even in an e34.
                    I bought my e34 for $400 due to it being a timming belt victim, the only thing the bottem end suffered was a couple of tinny marks in the pistons, that was with 10 bent valves....

                    I'm going the MS + turbo setup for mine.

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                      #25
                      Originally posted by ForcedFirebird View Post
                      Only if you over-rev ;)
                      I had a chipped ETA and the rev limit was at 5500. At about 5-5.2k the valves started to float, you could hear it and feel it. If you really want, you can put in the i double valve springs and cam. But you need to take the head off to do it, and while it's off you might as well just put the i head on.
                      1985 325e 2.8 Turbo VEMS

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                        #26
                        Originally posted by Danny View Post
                        I run 7psi on my 10.5:1 m42.
                        Nice.

                        Originally posted by SamE30e View Post
                        I had a chipped ETA and the rev limit was at 5500. At about 5-5.2k the valves started to float, you could hear it and feel it. If you really want, you can put in the i double valve springs and cam. But you need to take the head off to do it, and while it's off you might as well just put the i head on.
                        Why can't the springs be changed with the heads on? I've done it multiple times on various cars? Take the spark plug out, feed some 1/4" rope in the hole until no more can fit, then rotate the engine until the rope holds the valves from falling into the cylinders. I've also used compressed air and a compression tester hose to fill the cyl with air, it will hold them up as well but more times than not, it's a pain to get the hose in there or it gets in the way while working.

                        I will probably end up doing the head top end swap, but started this thread because I was reading old threads and saw how many times it's mentioned that there's too much compression and the i head is a MUST.

                        Here's a good example of high CR and boost on a BMW...

                        john@m20guru.com
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                          #27
                          Originally posted by SamE30e View Post
                          I had a chipped ETA and the rev limit was at 5500. At about 5-5.2k the valves started to float, you could hear it and feel it. If you really want, you can put in the i double valve springs and cam. But you need to take the head off to do it, and while it's off you might as well just put the i head on.
                          would there be any power increase with this swap on an NA car?
                          Originally posted by kronus
                          pff, all of you are slow as hell anyway. Eta > all

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                            #28
                            everyone always thinks having a butt-plug for a head is going to help a turbo spool up faster. quite the opposite is true, a stuffed up head is going to lead to higher EGTs, lower knock threshold and lower overall power, in addition to spooling slower. And given the same pressure, the I head is going to flow a lot more than the e head regardless.

                            there is a thread that shows the flow rates of the different M20 heads on e30tech.. I don't have a link but somebody did some pretty extensive testing. the 885 is up there with the porsche 2v heads and the LS1, the eta head just can't compete, especially if you do some port work and throw in a nice cam.
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                              #29
                              Originally posted by nando View Post
                              everyone always thinks having a butt-plug for a head is going to help a turbo spool up faster. quite the opposite is true, a stuffed up head is going to lead to higher EGTs, lower knock threshold and lower overall power, in addition to spooling slower. And given the same pressure, the I head is going to flow a lot more than the e head regardless.

                              there is a thread that shows the flow rates of the different M20 heads on e30tech.. I don't have a link but somebody did some pretty extensive testing. the 885 is up there with the porsche 2v heads and the LS1, the eta head just can't compete, especially if you do some port work and throw in a nice cam.
                              On the contrary, I completely understand the concepts of boost, here is an example of the head I went from to in my Firebird.

                              Stock intake flow is about 127cfm at max lift (.400")...



                              To about 225cfm at max lift (215cfm at the same .400")...




                              And both units ported (147cfm and 250cfm respectively)...







                              Again, this thread isn't going in the direction I expected. I was hoping for a discussion on static compression and boost...
                              Last edited by ForcedFirebird; 02-10-2009, 01:03 PM.
                              john@m20guru.com
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                                #30
                                I wasn't really speaking of you specifically, there were some other comments in this thread that lead me to post that.

                                anyway, you are right that a static 9:1 CR won't neccesarily hurt you under boost. The big thing is going to be exhaust restrictions and the cam profile, that will control where your knock threshold falls for a given compression ratio. basically the higher the static CR, the more agressive your cam needs to be and the less restrictive your exhaust should be. Which essentially means a high CR eta block with the stock eta head, cam and exhaust is going to have a much lower knock threshold than an engine with the same CR and a better flowing head.
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