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Thread: HE351 OMNI Which manifold??

  1. #1
    Supporting Member Turbo Mopar Contributor GLHS60's Avatar
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    HE351 OMNI Which manifold??

    This probably has been covered but I couldn't find anything conclusive.

    I'm getting ready to choose an exhaust manifold for my 8V Holset build.

    I have a ported stocker and a cast TU with the Chrysler bolt pattern.

    How are you guys re-drilling these to the standard T3/Holset pattern?

    Using one stock stud hole (which one) and adding/drilling 3 more??

    Or drilling four new holes within the original Chrysler bolt pattern??

    Any manifold pictures and or comments would be greatly appreciated!

    Some have used a stocker/Holset/ ZF PS pump combo successfully??

    I think the Holset /TU combo will be crowded in the brake area??

    Sadly, I lost my manual brake firewall plate so I'm stuck with a booster.

    Another choice is a TBI header with a suitable flange installed.

    Anyone have experience with this combo fitting/flange angle wise??

    Any comments, pictures or recommendations are highly appreciated!!

    1: Holset/stock exhaust manifold.

    2: Holset/TU cast manifold

    3: TBI header/Holset

    Thanks
    Randy


    There is no logical reason to call an Engine a motor.

    Randy Hicks
    86 GLHS60
    86 GLHS 373 : SOLD, but never forgotten
    89 Turbo Minivan
    83 Turbo Rampage : SOLD
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  2. #2
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    Re: HE351 OMNI Which manifold??

    You'll have to drill and tap all 4 holes.
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  3. #3
    turbo addict
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    Re: HE351 OMNI Which manifold??

    if you have questions about the TBI/turbo header arrangement send Jay ..GLHS&SLH2 (?) a PM
    he posted a couple years ago , pics of his set up using that manifold

    it puts the turbo "way down" by the steering rack and I think you might have to choose wisely which outlet you use for clearance reasons

    if you want a ready made TBI/turbo manifold I have one .. it's a little "hack-ie" maybe and one of the turbo mounting studs is a little crooked
    bought it about 10 years ago from "some guy" on TD who had big plans to make a batch .. I'v got the first and only of those here

    it's drilled in the cryco pattern and it's good n rusty ....40 bucks + postage if anyone wants it

    as for the regular bolt pattern vs the cryco one.. I believe the rectangle of the regular bolt pattern is actually smaller than the cryco style thus the four bolt holes fit within the footprint of the cryco pattern ..

  4. #4
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    Re: HE351 OMNI Which manifold??

    I had a TBI header, I don't recommend it. It's just too low. I barely fit in a CSX, I doubt it will fit a Omni especially with a holset.




  5. #5
    Supporting Member Turbo Mopar Contributor GLHS60's Avatar
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    Re: HE351 OMNI Which manifold??

    I appreciate the pics and comments Harry !!

    You too Johnny.

    Thanks
    Randy


    There is no logical reason to call an Engine a motor.

    Randy Hicks
    86 GLHS60
    86 GLHS 373 : SOLD, but never forgotten
    89 Turbo Minivan
    83 Turbo Rampage : SOLD
    Edmonton,Alberta,Canada

  6. #6
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    Re: HE351 OMNI Which manifold??

    lookin at Harry's pics I'm thinkin .. the oil return from the turbo looks like a thing you might find yourself challenged by...

  7. #7
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    Re: HE351 OMNI Which manifold??

    Quote Originally Posted by Dr. Johny Dodge View Post
    lookin at Harry's pics I'm thinkin .. the oil return from the turbo looks like a thing you might find yourself challenged by...
    Mystryguy ran a modified TBI manifold. If I recall correctly, he had issues with the return and caused the turbo to push oil out the bearings. I don't recall his resolution, but he did get it figured out.

  8. #8
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    Re: HE351 OMNI Which manifold??

    I ran a TBI header for several years with no issues on the oil return. Sorry, mine was S-60 Chrysler bolt pattern. Flame spray welded. I had a fitting drilled into the oil pan. Factory oil drain tube became a vent to a catch can.
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  9. #9
    Boost, it's what's for dinner... Turbo Mopar Staff Aries_Turbo's Avatar
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    Re: HE351 OMNI Which manifold??

    todd what was your experience with power/spool increase/decrease with the TBI header? any knock sensitivity changes from cyl to cyl?

    im on a ported stocker right now but I have a TBI header swingvalve housing and i wonder if its worth digging up a tbi header and making a flange....

    Thanks,

    Brian

    Quote Originally Posted by turbovanman
    This one is easy, I have myself to blame, I rush things, don't pay attention to gauges when I should, change to much stuff at once then expect miracles, the list is endless.

  10. #10
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    Re: HE351 OMNI Which manifold??

    thanks for that pic Todd..

    looks like a reverse rotation Garrett MIGHT fit?? ... better? now they actually make such things..

    EDIT.. second look .. maybe not considering the snaking around the end of the motor
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  11. #11
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    Re: HE351 OMNI Which manifold??

    Quote Originally Posted by Aries_Turbo View Post
    todd what was your experience with power/spool increase/decrease with the TBI header? any knock sensitivity changes from cyl to cyl?

    im on a ported stocker right now but I have a TBI header swingvalve housing and i wonder if its worth digging up a tbi header and making a flange....

    Thanks,

    Brian
    On my combo this was 2.2 in GLHT with fully ported head, pistons coming out of hole .025 or so, but not any added compression (bigger -22cc dish). S-60 turbo, Taft S2 camshaft, 568 tranny, stock sized Indy intercooler, and through TII airbox, with FWDP stage 5 LM calibration. This car had no detonation issues on pump fuel at 18 PSI. I had so much bottom end torque pretty much street tires where useless in first three gears. Maybe getting some traction from a roll at top of third gear. Oh, open diff too! This car was beggin for LSD! Spooling of turbo was NOT an issue, just the opposite in fact.
    I decided it needed a bigger turbo and camshaft to try to kill some bottom end out of it. Only took the car out to the track one time set up like that. I went 12.40's @ 114 MPH on 18 PSI on small 23" M&H's. Sold the car to Jessie B. and gave him the choice of the car as is, or with +1mm Manley valves, upgraded valve springs, and S-46 Turbonetics turbo w/ATP swingvalve with extensively ported log manifold (stuff already purchased). Jessie opted for option #2 after driving the TBI/s-60 combo for a while. Attached is pic of what we added. I did the head/exhaust work and Jessie bolted on the parts. The car initially ran about the same at the track, but definitely lost a bunch of low end torque from bigger turbo. It ended up running 12.0's or 12.1's at 115 MPH at same boost level. The car now has a bigger S2+ camshaft too. Still running Indy cooler and stock airbox. Below is pic of car the way it sits today. One good launch away from 11 second timeslip. Sort of wolf in sheep's clothing.
    I still have the manifold available for purchase. Flame spray welding isn't cheap, so low ballers beware (lol). Welded swingvalve & downpipe I sold.
    The thing I didn't like about the TBI header in a l-body is how close the 3" downpipe comes to the steering rack. I had that area wrapped because the rack boot had to be removed for clearance. That could have been improved with addition of the ATP V-band swingvalve. To tell you the truth, I don't feel going back to the ported log manifold was that big of setback.
    Todd
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    Last edited by 4 l-bodies; 03-19-2021 at 02:59 PM.

  12. #12
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    Re: HE351 OMNI Which manifold??

    Quote Originally Posted by Dr. Johny Dodge View Post
    thanks for that pic Todd..

    looks like a reverse rotation Garrett MIGHT fit?? ... better? now they actually make such things..

    EDIT.. second look .. maybe not considering the snaking around the end of the motor
    Johny, my thought on that wouldn't it be harder fitting an internal wastegate on it? Seems like the actuator would need to be about where the turbos outlet or charge pipe would be. I agree, it is cool they make reverse turbos these days.
    Todd

  13. #13
    Boost, it's what's for dinner... Turbo Mopar Staff Aries_Turbo's Avatar
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    Re: HE351 OMNI Which manifold??

    Quote Originally Posted by 4 l-bodies View Post
    To tell you the truth, I don't feel going back to the ported log manifold was that big of setback.
    Todd
    Gotcha. I ported my exhaust manifold alot and the spool picked up nicely. on almost the same turbo but with the 50 trim wheel on a 2.5 with a stock G-head with a roller cam. Ported 2-piece lower with Lengel plenum. I'll just stick with whats on there now.

    Thanks

    Brian

    Quote Originally Posted by turbovanman
    This one is easy, I have myself to blame, I rush things, don't pay attention to gauges when I should, change to much stuff at once then expect miracles, the list is endless.

  14. #14
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    Re: HE351 OMNI Which manifold??

    Quote Originally Posted by 4 l-bodies View Post
    Johny, my thought on that wouldn't it be harder fitting an internal wastegate on it? Seems like the actuator would need to be about where the turbos outlet or charge pipe would be. I agree, it is cool they make reverse turbos these days.
    Todd
    LOL
    it was late .. I was "thinkin out loud"..
    that I think was what we could call a little flicker of light as opposed to a brilliant stroke of genius...

    previously when I got the manifold I was thinking with the issues being so close to the steering rack a v band outlet and an elbow ..IF you could add an external wastegate at the egr flange on the TBI manifold ???
    granted, I've never removed the block off plate on my manifold so I have no idea IF the passage is anywhere near the size of our internal wastegates
    but if similar to the size of the egr tube on a log motor , maybe , it could be reamed to size as needed.. and you already have two bolt holes to mount an adapter plate without welding another flange .. you know "IF"

    IF the egr port wasn't on an exhaust runner all by it's self.. that's where I set that manifold aside .. long time ago before ever seeing the V band outlet with the swing valve ...some ideas evolve into dead ends..

    though .. a TBI/turbo manifold .. in a north - south mounted drivetrain .. might work nicely IF the turbo was turned upside down so the turbine "snail" curves upwards instead of downward
    I think that might be the best purpose in using the TBI manifold .. making everything else much easier to "package" and route
    Last edited by Dr. Johny Dodge; 03-20-2021 at 02:31 AM.

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