1HD-T Intake Manifold Modifications

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rumor has it adamB has completed his plenum mod with excellent results.
Now if only he would chime in :)
 

Tapage

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just felt like walking in my buddy's shop and you telling me that about Adam .. the guy who's gonna show later on ...

Gotta love internet and MUD ..
 
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Complements of Mitch92 here on the forum.

Apparently it interferes with the 12mm pump he is putting on his 1hz

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Looks like the china knock off of the Veilside supra intake manifold. They flogged those hard in the Supra world for a few years. I would watch for casting flaws and slag inside, looked at a few that all have the same issues.
 
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my 2# i had nothing but surge issues when i biult a taperred manifold,changed the design on the advice of a turbo engineer as a process of elimination (he didnt think it was the turbo again), and bingo he was right .
 
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http://www.ebay.com/itm/toyota-supr...Parts_Accessories&hash=item4172a666fa&vxp=mtr

Yep looks to be a modded supra intake manifold.

I think I am just going to be welding 3" pipe to the top of mine.
Still unsure on what intercooler I am going to use and how I am going to mate the two together.
I want to just make sure the intercooler core is even in the center of the hood for when I have to cut a hole into it.
 
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http://www.ebay.com/itm/toyota-supra-2jz-gte-2jz-ge-intake-manifold-/281096382202?pt=Motors_Car_Truck_Parts_Accessories&hash=item4172a666fa&vxp=mtr

Yep looks to be a modded supra intake manifold.

I think I am just going to be welding 3" pipe to the top of mine.
Still unsure on what intercooler I am going to use and how I am going to mate the two together.
I want to just make sure the intercooler core is even in the center of the hood for when I have to cut a hole into it.

The quality will be better if you build it, so thats a bonus. There are a few metal supply stores here that sell 3",3.5" and 4" Aluminum pipe I would just get one of those and mod what you have. Gets a bit tricky to make sure you are getting balanced flow of air to each cylinder. When we where messing with one on my Supra we had 6 EGT probes to make sure we had it as balanced as possible.
 
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rumor has it adamB has completed his plenum mod with excellent results.
Now if only he would chime in :)

just felt like walking in my buddy's shop and you telling me that about Adam .. the guy who's gonna show later on ...

Alright, alright. Sorry to take so long. I gained a lot of good information from this thread so I gotta give back what I can...

FIRSTLY, huge thanks to Karter (ForealBoreal) for sending me an intake manifold so I could do all the work with NO downtime. I built the new plenum off the vehicle and once it was done I was able to do the swap and get all the remaining details done in a single day.

I usually get too busy actually doing things and don't take a lot of photos along the way. This was no exception! I didn't take any photos of the inside of the intake manifold but that doesn't really matter. I have a few "after" shots with it installed.

My method was fairly simple. I got a length of 4" 6061 aluminum tube with a 0.125" wall for the main portion and a piece of 3" for the center entry from my water-air intercooler. I did all the obvious measuring and planning and I must say that this was one of the few times when everything just worked with very few difficulties along the way. I haven't TIG welded before but we've had a spool gun for our Miller 252 kicking around the shop for a few years so I decided to learn to use it. I put in a couple of hours of practice until I was comfortable with the 1/8" material. I actually practiced on 0.090 which was somewhat difficult for a rookie with the spool gun. For those who actually know what they're doing it's probably easy but I found it to be impossible to do a spray transfer on that thin material and ended up doing it with short circuit welding exactly how I would have with mild steel and the MIG setup. The only difference was prep, always pushing, and a little more distance.

Anyway, I cut the top off the original manifold, machined out the little divider wall and the inside of all the threaded bosses that I wasn't going to be using, tapped a couple of them 1/8NPT for my boost hoses and a thermocouple, smoothed out whatever casting crap I could, did a bit of port matching, used 3 and 4" holesaws to make nice curves so the parts would fit without gaps, welded it all up, spent ages grinding things smooth where the parts met, then cut a couple of 3.75" end caps from 1/8" material and welded those on. I cleaned up a few spots with a flapper disc just to look nicer but for the most part the spool gun did the job and I'm happy with how it all turned out.

I had raised my throttle assembly prior to doing this job so I wouldn't end up running out of time on the big day. I just made a plate to raise it ~3" and cut+welded the arm at the bottom so it ended up in approximately the same position. I think the best way would have been to modify the top as others did but mine worked out just fine. I was able to maintain the oil and trans dipstick positions, didn't quite hit the coolant hard line on the firewall, pwr steering reservoir attaches the same, and none of the fuel lines touch the new plenum.

RESULTS: After cranking the starter forever and finally getting it started again (it didn't occur to me that my pusher pump can't fill the injector lines :doh:) I hopped in and drove. I was expecting a little bit of lag with the big 4" plenum but it seems to be quite the opposite. It feels more responsive right from a dead stop. I've taken it up to 3800rpm a bunch of times and it breathes very well. It just seems happier when I ask it to rev. It feels smoother and sounds better. I was immediately able to see a difference in EGTs. Just based on experience and paying a lot of attention to these things all the time I feel that I've knocked about 100F off the temperature any time I'm on it hard.

I have absolutely nothing negative to report.

Unfortunately, this is NOT good science as I made other changes at the same time, because it was the logical time to do so. Because I moved my intercooler to a better position I was able to dramatically improve the intake path between the turbo and the intercooler. I removed over 90 degrees of very tight bend and in the process of doing all this I gained 2psi to my max boost without any changes to the boost controller. I've always measured boost at the manifold so while I was running at 20-21psi (which actually creeps to 22 at sustained high elevation full load) my poor 1st generation Grunter has been pumping up to 24psi (almost 3:1 pressure ratio at 5000' above sea level) and it hasn't choked to death in the 2 years I've been using it.

PHOTOS:

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You can see I've just raised the throttle assembly with a piece of aluminum plate:

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Water/methanol nozzle sprays right at the plenum entrance, thermocouple can be seen just below that, adjacent to the 3 way boost signal splitter and oil dipstick:

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The path from the intercooler to the plenum is smooth, all 3", and only a 45 degree bend:

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This is the path from turbo to intercooler now, less bends and the diameter changes are way more gradual...

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And this is the POS adapter I had been using previously with a hard 90 and a 180 and then a 2.25 - 3" jump...into the trash where it belongs!

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So with all these mods and gains, how is the rest of the truck (transmission/torque converter) holding up?
From what I have seen and experienced, just tweaking the stock power a little bit has negative affects to the transmission on these rigs (shuddering and other scary noises).
 
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I have a Wholesale valve body and when it went in ~6 years ago I remember the shifts feeling really firm.

I had the transmission fluid changed at ATEB about a year ago and since then I've felt like they're a lot less firm. I'm thinking it is just different fluid causing the different feeling. Now if I'm pushing moderately hard and it shifts it almost feels like there's some slipping going on for a second, then it's solid again. I can't really see an rpm surge then decline like you get in a manual with a slipping clutch.

It seems to be related to the auto shifting - if I manually hold it in a gear I can step on and off it as hard as I want and it feels solid. Also, when the TC is locked it always feels solid.

I still haven't experienced the shudder wrongwayaround described.
 
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looks nice adam. good thing about wta is the short run forsure. i think the real bonus you'll see is at higher revs on the freeway.i did see a gain in things with a kn filter in the airbox and a bigger smoother airbox to turbo piping,plus it got rid of some turbulance noise.hats off to foreal for the up front loan intake too.
 
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Adam,

Glad to know it worked out so well for you. I am happy to help out another cruiser owner.
Since I wasn't needing to mod it right away I figured it could help you out.
Would be happy to do something like that again.

I'm also really happy it turned out so well for you, I'm looking at spacing to fit everything for my intercooler set up with the plenum and its freaking tight. I might only be able to fit a 3" pipe depending on how its adapted to the manifold. Heater hoses are in the way and hood clearance is another issue.
I really wish I had the spacing of the 80 series engine bay for this project.

Cheers!
 
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Good work.

I have also found that extra volume for intake parts (though I was working with piping, not manifolds themselves) has a positive effect on lag.
IMO the fear about extra volume causing lag comes from petrol suck-through turbo days and doesn't apply to diesels.

Isuzu make a marine 4BD1 which individual runners open to the atmosphere (the boat is the plenum). This says to me there is no upper limit on plenum size. Only the tradeoff for each individual installation.
 
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Have to dissagree here Dougal. I know what the math says, and I know what results say. By reducing the intake plenum size only slightly, made a noticable difference down low.
 
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Have to dissagree here Dougal. I know what the math says, and I know what results say. By reducing the intake plenum size only slightly, made a noticable difference down low.

Low steady state or low spoolup? What was the before/after size?
 
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