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Thread: Turbo 084

  1. #21
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    Re: Turbo 084

    if the efi works out i woudn't have to do any thing to my setup but disconnect the carb to the turbo. i am using an 1 5/8 exhaust pipe to spin turbo and i plan to replace the crossover with an 1 1/2 pipe. it can't hurt. casey said while watching my gauges he saw the boost gauge go to 5 pounds. not sure it did but trying to watch the egt. cht. oil pressure. and boost gauge also the wideband gauge most important one and remember all that was going on gets a little confusing. after all is finished and i am happy with it i am going to replace piping with stainless if i ever get that far. always seeing something that could be made better but to find out that it will work is a big relief to me.
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  2. #22
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    Re: Turbo 084

    Here is some pictures to show what i did with the turgo setup. it's really rough now but still give you an idea of how i mounted every thing. everything was going to plan until i fabricated the exhaust pipe to muffler. i lost 100 rpm from too much back pressure. i was testing before with out exhaust and muffler and was turning 4200 rpm with 3 pound of boost now with exhaust and muffler i still get 3 pounds of boost but 4100 rpm. going to take muffler off and try that. if it doesn't help i will go to 2 in exhaust instead of 1 5/8 in i have now. if taking the muffler off fixes it i'm going to cut the baffle out of muffler. also with the added back pressure it stumbles slightly and takes longer to get top rpm's.which is expected. other than that it was performing better than i expected. oh and i had to remove power valve diaphragm and block the port to it to stop running rich when the boost came in. it runs 12 percent a/r at wide open throttle before it was 9.9. going to play with power valve to see if i can change the way it works with the added boost.
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    Last edited by bgmcl60; 06-21-2018 at 08:40 AM.
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  3. #23
    Junior Member Bart's Avatar
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    Re: Turbo 084

    looks like you are having fun with the design, it has came a long way from the first picture,
    it was looking complicated with trying to go with a 4 to one adapter. but how you have tied it together, it looks pretty simple.
    i have been trying to read up on what others, with different, but similar CC motors have done. to try to get some insights of the problems that they have overcame.
    but life gets busy,
    but from compression boost ratio charts. it looks like with a 3 pound boost. it has upped the compression from a stock 6.5 to around 7.9 ratio.
    https://www.rpmoutlet.com/boost-comp...atio-chart.htm
    I hope that all goes well, as you trouble shoot the little things that may come up as you go forward with this.
    it seems like if i remember from reading some other forums and postings, when others would shave the heads, they figured on getting around 8.5 ratio. but there was always a couple of unknowns that they never mentioned, how much they shaved off. and they never mentioned using a wide band air fuel gauge.
    I'm glad that you have the gauge, it has got to help out a lot.
    cant wait to see where it goes from here.
    Last edited by Bart; 06-22-2018 at 07:42 PM.

  4. #24
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    Re: Turbo 084

    i changed the exhaust to 2 in into a 2 1/2 muffler cherry bomb and 2 1/2 out of the muffler. that got me 4150 rpm. going to run it in a couple of days and try to get a video if it runs good enough. first i have got to bring the pitch of prop up to hold the 084 to 3600 rpm. and we will see what happens. going to change the oil and fix my oil temp gauge then be ready to go. these pictures were taken with different phone sorry for the blur.
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    Last edited by bgmcl60; 06-22-2018 at 09:41 PM.
    4a084
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  5. #25
    Super Moderator Corky's Avatar
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    Re: Turbo 084

    Good luck on the trial run.....There's a lot of engineering going on there thanks for taking the time to document your progress..
    Amazing the exhaust size has such an affect on the RPMs but it makes sense.. I know from a hydraulic perspective {water/pipe restriction} there's a formula for just how much straight pipe needs to be used inline before any 90* fittings should be used...It varies depending on the pipe diameter...I would assume the intake tube/exhaust would have a similar formula for the turbo to have optimum performance..But I'm sure it's all a compromise between the available space vs a completely optimum intake and exhaust system..
    I've got some high hopes with you running this and possibly fine tuning it to the point of some serious gains in the long run...

    Aluminum .120 14' X 76" hull
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  6. #26
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    I've got a question? If i had installed the exhaust backward from what the factory had it like the cross over being on the rear of engine instead of on the front. Would that affect each exhaust pulse? Also do i need to put a larger cross over on the engine. I had to repitch the prop to 10 degrees to hold the rpm's to 3500 rpm. I had to have the 2 blade pitched to 7.5 degrees to get 3600 rpm. I now have 2 lb's of boost turning 3500 rpm. What should i do. Try to get more boost or leave well enough alone? It's doing right now what i was hoping for but always looking for a little more. I've been a mechanic for 40 odd years and always looking for advice. Nobody knows it all.thanks in advance. Bobby

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  7. #27
    Super Moderator Corky's Avatar
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    Re: Turbo 084

    I know what you're saying about more...After a while a little more here and a little more there adds up especially with what's to be gained here...
    To answer your question :
    I do think there's more to be gained by reworking the exhaust...At the factory low compression that exhaust wasn't a factor...But now you've bumped the compression up and more exhaust gasses are being pushed through that same configuration...As the exhaust gasses cool they also require less space and I bet the factory figured with the low compression/cooling affect the cross over was adequate..Now, The cross over pipe would be a factor for back pressure being generated for that side to overcome..
    Ideally to squeeze all this engine can give, as with a race header you'd want each primary tube to be equal size and length before the collector...And so the reasoning for some crafty bends and turns for the pipes to all end up at the same place{Chuck at airboat pros had what he considered to be a magic number for equal primary tube length on the 084}...You'd need to take the longest run and take the most direct route to the merge point to get your runner length and go from there...
    Next category is where most exhaust headers fall : Same size primarys but unequal lengths...Due to space limitations or obsticals in the way..At the cost of a few HP and torque numbers...
    And lastly at the very least IMO..Most small diameter cross overs are used in a dual exhaust type setting to equalize the pulses,not to bring a whole engine bank over to another log so yes the bottom line is at least bump up the cross over to the same size as the logs..
    Last edited by Corky; 06-27-2018 at 11:02 PM.

    Aluminum .120 14' X 76" hull
    Teledyne 4a084-4 engine
    Circle S 1.69:1 reduction
    67" Whirlwind "Razor X" prop



  8. #28
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    Well i took your advice and thought i had messed up until i got to checking the exhaust closely and found a blown out gasket that blocks the exhaust off on left side. Made a new block off plate and added another gasket and that took care of leaks. Now i can get 3600 and 3 pounds of boost on trailer. Maybe more on the water. The exhaust cross over is1 5/8 in and the largest i can use unless i build new manifolds. I think after i water test it i may get my pipe bender set up to make some mandrel bends and build another 4 into 1 exhaust. I think that would get me more boost and also try the blow through setup. Everyone says it performs better than pull through setup. Just wait until i test it on the water and with no water and see how it performs. Even without the turbo it ran dry ground. Just needed some grass to mke it slick.

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  9. #29
    Super Moderator Corky's Avatar
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    Re: Turbo 084

    OK now it's clear what you've got for the exhaust...Glad to hear it's up to 3lbs...I can't wait to see it in action !!

    Aluminum .120 14' X 76" hull
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  10. #30
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    Re: Turbo 084

    No video. ashamed of how it runs. got a bunch of frogs though. well back to the turbo. i guess i dont understand all i know about turbos. it would turn 4200 and 3 pounds boost prop set at 6 degrees. changed pitch to 10 degrees and 3 pounds of boost at 3800 rpm. all this you would think it wood be a hill runner but actually it ran worse on low end and took longer to plane. after it got on plane it would run faster than it did before. my conclusion turbos dont like low end and doesn't start making power until after 3000 rpms. my boat has more low end with 32/36 weber. what i don't under stand is before i had to pitch the prop to 6 degrees to get 3600 rpms. today i disconnected the turbo and installed the 32/36 weber. at first it wouldn't idle until i readjusted the air mixture and smoothed out fine. thing of it is now at 8 degrees of pitch it turns exactly 3600 rpms. only 200 less than with the turbo and more pep at low rpm. don't know if something happened to tach or something else. i know these observations doesn't mean anything to someone else. there numbers could be totally different. so i will go back to the tried and true carb for now until papee or someone else can get more out of a turbo. like i said we got a lot of frogs last night. we got permission to gig a private lake and the last frogs we gigged were babies compared to these.
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    Last edited by bgmcl60; 06-30-2018 at 08:50 PM.
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  11. #31
    Super Moderator Corky's Avatar
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    Re: Turbo 084

    Those are some nice frogs !!!... I was hoping to hear or see how well the turbo performed...I'm not well educated on just how much boost that size turbo needs to have throughout it's rpm range to make it work at an acceptable level...I wonder if the compression is too low for it to work well at low rpms..

    Aluminum .120 14' X 76" hull
    Teledyne 4a084-4 engine
    Circle S 1.69:1 reduction
    67" Whirlwind "Razor X" prop



  12. #32
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    I beleive if you set it up to rev higher it would work a lot better. But you can't run an 084 4 to 6 thousand rpm and it hold togetther. When i pitched the prop to hold the rpm's down to 3600 the turbo was just starting to work. If i had left the pitch where it was turning 4200 it would have performet a lot better. I just don't like running 1 that hard.

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  13. #33
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    Re: Turbo 084

    My thought on the performance issue is that the higher the RPM the more air is going through the exhaust which spins the turbo faster, developing boost. If there is not enough exhaust to spin the turbo fast enough to create boost it will act as an intake restriction rather than an intake pump. The symptoms described are similar to what I have heard from my neighbor who put a larger-than-recommended turbo on his Mustang. He complained of no grunt on the low end and had to be near redline before his boost started kicking in. His impeller speed wouldn't hit 100k until 6000 RPM.

    I wonder if you could find a smaller turbo. If you were able to spin a smaller turbo faster at lower engine RPM it may help. A good indicator would be to use a non-contact tach on the turbo to see what speed it is running at. Just a thought.

  14. #34
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    Re: Turbo 084

    just what i was thinking.higher rpm's it did work better but to the expense of the engine. more wear and tear. i was looking at a vz21 turbo that is about 1/2 less diameter on all ports. smallest is less than an inch. may be too small not sure. kinda been waiting on papee to come up with a better idea on this tur bo that will work. maybe after this season is over and nothing to do i might try the smaller turbo.
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  15. #35
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    Re: Turbo 084

    This is why I went with the smaller turbo hoping it would spool faster. In my mind the exhaust pressure has to be as high as possible by using a smaller diameter pipe without restricting the system.

    By using a smaller pipe you raise the exhaust pressure. Think about blowing through a 10" piece of garden hose then through a straw. The pressure would be higher in the straw.

    Next is the efficiency of your header. It needs to flow without interruption or restriction. (Here I think using the stock exhaust is hurting you.) Next is the exhaust pulse, it needs to be as equal as possible so there is maximum efficiency turning the blades and not working against another pulse. Chuck and vhf I talked a lot about header lengths. I will be designing mine to keep each tube the same length in multiples of our original header length.

    All this mumbo jumbo is from my brain and not fact. I was going to go in depth in my build but I'm a little slow at getting started. It will be happening very soon, I'll finally have ac in the garage in the next few days. It's been a hot one this year and the heat really is bad for me so I'm limited on garage or outside time. I am finally about done with Tony's boat(app64) then it's on to mine.

    I'm sure there's much of my theory that I've left out. I'll try to be more thorough when I get started.
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  16. #36
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    Re: Turbo 084

    Don't hold me to anything here I'm just reading and thinking. I think you guys are on the right track with the smaller turbo. It will spool up at lower rpms the only thing i was worried about is to much back pressure. I was wondering if an external Wastegate hooked to the exhaust pressure would prevent any damage from it even just a exhaust valve that you can control the air going to turbo. If you look at sequential turbos they use a smaller turbo to get boost at the lower rpms then a larger turbo kicks in at the higher rpm. You can use the same idea without the larger secondary turbo. I have a diagram of one to show kinda what I'm talking about. Also have a pic of my old exhaust which i think would work well for you wish I still had it I'd give it to you.
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  17. #37
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    Re: Turbo 084

    I think papee is right my factory exhaust hurt the performance with too much restriction. i wish i had used pipes straight from exhaust down pipes instead of the manifolds. might have seen a better outcome. when i had the larger turbo on i used flex pipe to run to turbo and that hurt me to. but i do believe the turbo is the right size. next smaller seems too small at about 1 in outlet.
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  18. #38
    Member yamahaulerG1's Avatar
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    Re: Turbo 084

    I agree the 1" outlet seems to small that's why i was thinking about the secondary exhaust outlet feeding just enough air to the smaller turbo allowing it to add boost from around 1000rpm-4000rpm instead of 3000-6000 like most turbos are designed for.

  19. #39
    Junior Member Bart's Avatar
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    Re: Turbo 084

    i have a lot to learn about the mathematics and plumbing for this,
    was looking at a few utube videos and there are just a few different ideas out there, that could make this work
    haven't quite rapped my head around the theory of all of this yet, but the 2 links below have 2 different approaches to it. the first one uses bypass valves and in the second link. they plumb it a little bit different. just a lot to learn and sort out.

    https://www.youtube.com/watch?v=DRcmgibm-aA
    https://www.youtube.com/watch?v=QRTFjYsX5vI

    by the way i like how you did the cage, so you could work on the motor just a little.

  20. #40
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    Re: Turbo 084

    The first video is more like what I'm talking about. That was one of the videos I watched when reading about all this. And the cage like that is kinda nice but it looks better on 6cyl aircraft boats.

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