Choosing a Turbo for your IDI: Turbo Components, Specs, and Compressor Maps.

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Thewespaul, Oct 9, 2018.

  1. austin92

    austin92 Full Access Member

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    I remember that thread. It’s was like 2k? It’d be cool if we could group buy it down to like 800$. I’d buy one


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  2. Macrobb

    Macrobb Full Access Member

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    So, speaking of turbo maps and such - can you go backwards?
    I've got this S360 turbo, with a .63 exhaust housing. What info can you come up with me for it.
    Also, I'm still trying to figure out why this same turbo with a .83 exhaust housing spooled like **** and I got 10 psi out of my setup(with tons of smoke), yet when I put the .63 housing on it, it'll spool to around 25 easily, with little to no smoke.
    This was with a RD2-110 pump and Banks Sidewinder piping(up-pipe, down pipe. crossover etc).
     
  3. Booyah45828

    Booyah45828 Registered User

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    A lot of interesting data here.

    I've always had a few questions in the back of my mind regarding turbos that hopefully you can answer.

    I've read on here that a member(I thought it was you wes) reached a limit where more boost no longer produced benefits. I think they attirbuted it to high drive side pressures in the turbo. My thoughts is that that scenario could only be caused by too small of an exhaust housing on a setup with no wastegate.

    Wouldn't installing a wastegate or swapping to a wastegated turbo eliminate this issue? I mean, barring having a 40 mm exducer on the turbine, I'm struggling to see how you could have so much drive pressure to cause such an issue.

    I'm not sure which turbo was being used in question, so maybe it was non-wastegated, but my question still remains.
     
  4. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    I think the lowest I could see that coming is 12-1500. Unfortunately I’m just a supplier so I don’t make the prices, just help supply the product to the customers, if there was a significant interest I could arrange a group buy, but I doubt it will ever get to that point, very few people make enough power to slip a luk
     
  5. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Remember these maps are compressor maps, so they show the cold side flow characteristics, not hot side which you changed and got better performance. A turbo has to spool up to a certain rpm to make x amount of flow in the cold side. Think of the hotside like an air compressor and the pump is the engine. By changing the ar of the housing you are making the tank smaller so it will fill faster. If you have a leak or not enough drive pressure you will never reach the necessary rpm to make boost. I think if you tried an off the shelf turbo you would have much better results, instead of a customized second hand turbo. I have a customer with one of my 100cc pumps and a precision 62/62 with a .82 t3 hotside and he makes 25 psi peak and 3 psi at 1500 rpms. More boost and more responsive than the factory turbo.
     
  6. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    I remember mentioning that, I believe it was when I had my experimental big pump on the shop truck and made 27 psi through the factory turbo. It was wastegated so I hooked the turbo back up and adjusted it to 20 psi, and was making the same power. A larger housing would be an improvement, but the wheel is the real restriction. Unfortunately the housing on the factory turbos are proprietary as far as I know, so it’s a difficult platform to upgrade, which is why I am encouraging people to go with a newer, better designed turbo.
     
  7. Goose_ss4

    Goose_ss4 Full Access Member

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    not to throw another wrench or stir the pot. but what of your thoughts of true twins? one on each head like that jaguar sled pulling car. i think they are running k27 or k17 turbos on there with a p pump. obviously this for sled pulling only, but what the applications for this for everyday use?
     
  8. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Only practical application is if a larger enough turbo is not available or there’s no room for a larger turbo. If you’re not racing one single turbo has a lot less to break than with twins
     
  9. Goose_ss4

    Goose_ss4 Full Access Member

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    fabrication only aspect that seems to come to mid as far as cost effective mean. as apposed to creating a exhaust manifold x2, transition to the up-pipes, the up pipes, transition to a turbo flange and turbo mount that fits between the valley intake manifold oh and btw the firewall. Im not saying it perfect but there is some benefit. i hate to say but i though this was brought up in another thread long ago. that the conservation of energy with the cummins setup being on the exhaust manifold itself. instead of shooting down around a transmission like the factory kits.

    2x s200 or some garrets that could spool effectively would benice.

    thoughts or criticism welcome
     
  10. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Remember you still have to fit a downpipe in there As well as vertical oil drains that can’t have more than 15 degrees from vertical, and the cost would be double what a single turbo would be. It would be cool, but there wouldn’t be room without loosing the accessories or the inner fender wells. I think it would be fun in a fairmont or something of the like, but for a heavy truck it wouldn’t be very responsive. I built a third gen camaro with a ls and started with twin 62/62s and went to a single Chinese 88 and made wayy more power with just as much lag as the twins
     
  11. BrandonMag

    BrandonMag Dana 50 rebuilder Supporting Member

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    The first post that started this thread is a great example of a difficult to understand topic made accessible by the use of everyday language.

    Great explanation; keep up the good work!
     
    ttman4 likes this.
  12. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Glad it has helped, I try to break it down as simply as possible although they are complex topics. Got a second addition in the works once I get some time
     
  13. Chemgrad

    Chemgrad Full Access Member

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    As always nice job explaining a complicated subject thewespaul.
     
  14. Chemgrad

    Chemgrad Full Access Member

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    Quick question at what pressure level are head studs needed and at what point would you recommend putting in head studs. Unfortunately the turbo swap I started years and years ago didn't really work as I'm only getting circa 5-7 psi at WOT. I've got another turbo to replace that one however and hopefully it will work. Planning on either selling the truck or giving it to my parents after I get in running again now as I gave in and bought a truck, used because I can't see spending 80k on something that won't do 155 at least ;burnout
     
  15. Alwaysreadyrob

    Alwaysreadyrob IDI TURBO

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    Thanks for dropping that knowledge. I read something about stock Rods here. I have a 1994 K Vin 7.3 IDI, I think it makes with the turbo about 125 Hp. It has 306,000 miles on it. Would i have to pull the engine out of the bay to put an R & D stud kit on it ? My goal is about 300 hp. Am I in danger of blowing my engine trying to get that out of an old engine like that ? Also i have only removed the crimped down pipe but the rest of exhaust is stock but i plan to go 4” exhaust with stacks and clapper caps.
     

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