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My 4.0ohv turbo build thread

turbo cat

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Well I finished the slight modification to the hotside. I ran the outlet of the first turbine back into the hotside downstream of the next turbo. So basically 3cyls are spooling the low pressure turbo and all cyls are spooling the high pressure turbo. It seems to be working so far. i still have adjustments to make like in the video you can hear it surging at idle due to a missing compressor inlet gasket (MAF vaccum leak). I hate flux cored wire but Im trying not to dump tons of cashflow into a DD rig.


 
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Iron Ranger

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I hate flux cored wire but Im trying not to dump tons of cashflow into a DD rig.
Yeah, that flux-cored stuff isn't too forgiving on thin metal(Trust me, I know:annoyed:)

But that seems to be coming together pretty good for you. Are you using the stock transmission or are you going to upgrade? Seems like it'll make enough power to blow the tranny. I dunno:dunno:, just curious.

Also, I watched your vid., is the idle loopage normal or just a cold start hiccup?

Sounds nice, too!!!!
 
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turbo cat

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Yeah, that flux-cored stuff isn't too forgiving on thin metal(Trust me, I know:annoyed:)

But that seems to be coming together pretty good for you. Are you using the stock transmission or are you going to upgrade? Seems like it'll make enough power to blow the tranny. I dunno:dunno:, just curious.

Also, I watched your vid., is the idle loopage normal or just a cold start hiccup?

Sounds nice, too!!!!
I usually MIG everything but Im broke as America so not wating argon saves me a few bucks. The idle issue is a missing gasket between the compressor inlet of the first turbo creating a vaccum leak after the MAF. Ill be fixing that tomorrow.
 

turbo cat

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adjustable vortech FMU
 

Sevensecondsuv

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How much did that run you?
 

turbo cat

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60$ there vortec's super Fmu with 5 adjustments can be used as a stand alone FPR also. They run about 300+ new
 

RacinNdrummin

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Well I finished the slight modification to the hotside. I ran the outlet of the first turbine back into the hotside downstream of the next turbo. So basically 3cyls are spooling the low pressure turbo and all cyls are spooling the high pressure turbo. It seems to be working so far. i still have adjustments to make like in the video you can hear it surging at idle due to a missing compressor inlet gasket (MAF vaccum leak). I hate flux cored wire but Im trying not to dump tons of cashflow into a DD rig.


Am I looking at that picture right????

Do you have the inlet and outlet of the one turbo going both to the hot side????

How the hell do you figure that will work???
--------------------

Dude that is a mess. You would be way better off running one turbo off of each side. A setup like that isnt compounding anything, its actually just using one turbo, the one with the pipe going in and coming out going to the same spot isnt doing anything.
 
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turbo cat

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It is working but I will know how well it is working after i run some tests and dial in the fuel pressure and hopefully tuning. Its called compound turbocharging. Its also how diesels can push 150+ psi into built motors. Im still running low boost but its kinda an experiment. if i can dial in the fuel a little better i will probally turn the boost up a few lbs maybe. The crossover you see in the picture isnt fully punched out it has a very small hole most of the volume is forced thru the first turbocharger before it enters with bank two. Either way its working. How well time will tell. The wierd thing is it was blowing off air in neutral free reving when the the throttle was shut. Compound turbocharging basically multiplys pressure ratios. For example you may have a setup that the first compressor takes the PR to 1.3 you will be at 4.9psi (19.6 absolute). Then compressor two having a PR of 1.3 it would be 19.6x1.3=33.12psi absolute-14.7 atmospheric=18.42 lbs of pressure. So you would go from 5psi basically to 18psi. If the wastegate controlls allowed this and depending on sizing and quite a few othr factors. Basically its multiplying boost. theoretically the two chargers would have to work less to achive the same ratio that one would have to work for however it all depends on sizing. For the best tests some tuning equiptment along with monitoring backpressure in the hotside. pressure output of compressor one and compare to outlet two.....
 
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RacinNdrummin

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I know what compound turbocharging is and I know how it works, but the way you have it setup isnt doing anything. Regardless of how small of a hole you have in the pipe that ties the two together, you cant have the inlet and outlet of the turbine housing go to the same spot. Those turbos are simply too small to build a compound system out of. You need a larger turbo that is after the smaller turbo on the hotside and before the turbo on the cold side. The way you routed everything makes no sense. You really should put one turbo on each bank, you would be way better off than have one useless turbo just sitting there, which is what you have with a hotside like that.
 

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x2 what RacinDrummin said, the way you have it set up is not doing anything.

I would run one turbo for each bank.
 

Sevensecondsuv

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That setup doesn't make any sense at all from a thermodynamics point of view either. The outlet of the hotside has to be lower temp and pressure than inlet of the hotside. The way you have the one turbo piped up, you would need higher pressure on the outlet of the hotside than the inlet of the hotside in order to acheive flow back into the exhaust stream going to the next turbo, even through a small orifice hole. That is impossible without doing work on the turbo, instead of the turbo doing work :dunno:
 

Sevensecondsuv

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That setup doesn't make any sense at all from a thermodynamics point of view either. The outlet of the hotside has to be lower temp and pressure than inlet of the hotside. The way you have the one turbo piped up, you would need higher pressure on the outlet of the hotside than the inlet of the hotside in order to acheive flow back into the exhaust stream going to the next turbo, even through a small orifice hole. That is impossible without doing work on the turbo, instead of the turbo doing work :dunno:
If you haven't already, you should consider getting an Mechanical Engineering degree. It's cool to see all the theory practiced in real life on a vehicle.

**Oops, it seems I hit "quote" instead of edit...
 

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well its working but im making some changes. The first turbo "thee one that woulnt work" is spooling fine. The only issue beyond that its spooling is that the turbo with only 3cyls of course is spinning slower than that of compressor 2. So of course compressor one dosent have a chance of creating boost due to the vaccum of 2 over coming the outlet flow of 1. So I made a change I reversed 2 to feed 1. It may not work im in the process of tinkering with it. io still have turbos of different kinds laying around and plenty o pipe. i may have to make some hotside changes. i have been planning on possibly rebuilding the whole setup and I have a few ideas that i know will work. These experiments arent costing but maybe 10$ a time so thats not that bad.
 

RacinNdrummin

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The reason number one isnt creating any boost is because you have no pressure differential at the turbine. You have to have pressure differential for a turbo work, and the way you have it setup right now is with equal pressure going to both the inlet and outlet of the turbine housing. There is still flow, that is why you think its spooling, but it isnt actually compressing any air. For that to work properly, you have to have a small turbo going into a bigger turbo, and even at that, your not increasing the flow capabilty of the exhaust side. Just run a turbo off of each side, there is no reason to have all of your boost in by 1500RPM, and if there is, just run a bigger turbo with a smaller exhaust housing like a .60/.48 or .60/.63 T3.
 

RacinNdrummin

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Also, before you throw anything else at that thing, Id get an intercooler on there and make sure your getting enough fuel. Then messing around with compounds and whatnot will be worth your while.
 

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