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Homebuild Turbo Truck No boost

Old 11-07-2012, 02:18 PM
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Default Homebuild Turbo Truck No boost

Hello DIY Boosters..

First let me introduce myself. My name is Laurens, and I'm trying to turbocharge my old Dodge (CUCV army) truck.

Things handy to know, I run my truck on LPG (liquid Propane).
I live in the Netherlands, therefore parts that are easily found in the US, are much harder to find here!

I decided to build my turbo truck for 3 reasons

1: to see if I could do it, and learn from it..
2: to achieve a slightly better fuel economy
3: having an unique truck with a punch...

So by knowing this...

My 1976 Dodge W200 army truck came stock with a LA 318 (5.2L) V8. Being a army truck it came factory with a small 2bbl carb (500cfm if i'm correct) and cast exhaust manifolds.



Due to the fact that I run propane and gasoline, I'm limited to a drawthrough system (at least with the stock components I have). Yet on the lucky side propane has an octane rating over 110, and is therefore less prone to detonate

I build my exhaust manifold myself see the picture. I combined cylinder 1 with 5 and 3 with 7. then combined those to into one (4 to 2 to 1 exhaust)



for the intake I made a carb spacer which is also visible on that picture. In the middle a sloped plate creating 2 closed chambers for the carb and intake. simply put one side is vacuum side (top part where carb bolts to) and bottem part the boost part (bolted to the intake).





The turbo I used is a TD04H-13C (volvo 940 turbo) , yes I know small.. But I'm not looking for massive power, just some extra punch, for towing and offroad fun. The CBV looked bad, So I blocked that off with a gasket and plate. I do use the factory wastegate which fully opens at 10 psi

Made a downpipe 2,5'' and connected that to the original exhaust system (where the original manifold also would connect..)

Now comes the problem...

Everything fitted, truck runs (seems to have slightly higher vacuum than before, gauge reads 20 Hg. When driving the car (putting it under load, on a small climb, WOT the gauge reads 5 Hg still, before the turbo setup it would go close to 0! Anyway No Boost!!!!!!

So I checked the obvious,

* Boost Leak test performed, fixed a few small leaks- System now holds 6 PSI with ease (including the manifold)
* Exhaust leaks - No obvious leaks found
* Wastegate stuck open, or actuator fell of - Still on, but can move the wastegate by hand, is that normal?
* Checked inlet hoses, and charge pipes and found a lot of oil... (drawthrough needs the right seal, but turbo came of a gasoline car and should have such a seal) with a diesel turbo you'd expect to find a gigantic amount of oil..

This makes me doubt whether the turbo is blown, wastegate broken (altough does open when you apply pressure) or some stupid design errors on my side? The carb spacer (lets call it a charge changer, from vacuum to boost..) has a quite restrictive inlet. around 30 mm is the smallest (same size as intake manifold has, where normally the carb would go, except there are 2 of those holes present..)

The Car runs, good on LPG, less on gasoline (but that was always the case).
I'm able to go about 45 mph before I reach 3500 RPM. (Normally without turbo setup I was able to cruise at 45 mph with 2800 RPM

Please poke your brain, and give me some opinions on what I did wrong or is causing my no boost situation...

Thank you in advance
Attached Thumbnails Homebuild Turbo Truck No boost-dodgecrosser.jpg   Homebuild Turbo Truck No boost-turbosetup.jpg   Homebuild Turbo Truck No boost-foto.jpg   Homebuild Turbo Truck No boost-foto1.jpg  

Last edited by Laurens; 11-07-2012 at 02:25 PM. Reason: images not working
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Old 11-07-2012, 03:56 PM
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i would look at the wastegate. the wastegate should be forced closed all the time via spring pressure. the wastegate will only open when spring pressure is overcome by boost pressure. put a vacuum gauge on the wastegate actuator. if the actuator doesnt hold a vacuum then it needs to be replaced. also some auto manufacturers use vacuum operated wastegate actuators instead of the normal boost operated wastegate actuators. a vacuum operated wastegate actuator is normally open and it is controlled by a solenoid which is controlled by the engine computer.
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Old 11-08-2012, 12:26 AM
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Hi Busa,

I'm pretty sure this wastegate opens when pressure is applied, I checked the volvo manual and it's connect to the turbinehousing (a very short vacuum hose).

Unfortunately I don't have a vacuum meter (except the one in the car), but sucking the vacuum hose should tell me the same I presume. I'll try that first (once I get home).

The spring of the wastegate holds a very slight pressure on the flapper, however I'm able to place the wastegate actuator rod on there without having to pull the rod.. Seems to me that there isn't enough pre-load on the spring anymore right! (unfortunately I can't adjust the actuator rod, its the fixed type...)

Also if I remember correctly, the wastegate opened smooth and fast when I applied pressure to it, but it also closes as fast. When I look at other people's wastegates (youtube there they opens as fast, but close more slowly. maybe another sign?

Any thoughts?

Last edited by Laurens; 11-08-2012 at 12:32 AM.
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Old 11-08-2012, 10:28 AM
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Ok a short update.. I've checked the wastegate and it holds vacuŁm.
Felt again on the wastegate actuator rod. I can move it with one hand and if I try
hard possible with one vinger.

Could too little pre-load cause a no boost situation?

I plan pulling the downpipe to have a better look on the wastegate flapper
And to see if there is oil aswell and if it spins still freely.

Another thought, could a too large intake restriction cause no boost?

And when you convert a nasp car, to turbo charged how does this change the ride
Exspecially when you loose boost alltogether (in other words how does it compare, Same vehicle nasp and turbo charged and turbocharged with no boost)

Last edited by Laurens; 11-08-2012 at 10:30 AM.
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Old 11-08-2012, 03:01 PM
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the wastegate rod should need to be forced on the flapper due to spring tension. if your just putting the wastegate rod on the wastegate flapper then there is no tension on the wastegate flapper. this will cause the wastegate flapper to stay open all the time creating a no boost issue.
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Old 11-09-2012, 12:38 AM
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I'll try to see if I can add some washers underneath the actuator to create more tension...

Also, how would the car feel like with a turbo added? Before I could hit about 60 MPH with 4000 rpm, now I'm struggling to reach 45 MPH with 3500 RPM...

Does a non working turbo added to a NASP car create these problems?
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Old 11-09-2012, 07:13 AM
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a turbo that doesnt spool up is just a restriction in the exhaust. less exhaust flow, less power.

as far as the wastegate actuator rod you can convert it to an adjustable rod.
cut it in the middle. and thread both ends of the cut rod. go to the hardware store and get two nuts and a threaded coupler with the same thread pitch as the threads you cut on the rod. assemble it and now you have infinite adjustment. the shorter the rod length the more boost. the longer the rod length the less boost.
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Old 11-09-2012, 12:37 PM
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Another update..

Removed the downpipe. Nothing obvious there, wastegate flapper seems thight.
Checked the pre-load again seems to be about 3 mm afterall. That seems about right.

Turbine spins but has some drag (does not keep spinning when you swing it), only checked exhaust turbine... I do for the first time hear the turbo spool with the downpipe disconnected. Seems to be a lot
of oil on the engine, another sign?

To recap, hear it spoolup but no boost, what could the cause be? Found a lot of oil in inlet, could it be a blown turbo? I did buy it secondhand, no real play on the shaft when I inspected the turbo

Once again any thoughts?
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Old 11-10-2012, 11:52 AM
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Ok another update,

Recieved the replacement turbo but it was in an even Worse
condition. It did gave me the option to swap out the wastegate.

Now I can clearly hear the turbo wistle. No boost still.
I'm starting to think that my intake is way too restricted. I did go from
a regular 2bbl carb to an intake box with an opening of approx 30 mm.
The turbo inlet is 60 mm but fed with a 40 mm pipe.

So my question. Could an intake be too restricted for the turbo, causing it not to spool up properly and there not being able to build boost?

Please give me some advise! Thans in advance
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Old 11-10-2012, 03:40 PM
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Originally Posted by Laurens View Post
Ok another update,

Recieved the replacement turbo but it was in an even Worse
condition. It did gave me the option to swap out the wastegate.

Now I can clearly hear the turbo wistle. No boost still.
I'm starting to think that my intake is way too restricted. I did go from
a regular 2bbl carb to an intake box with an opening of approx 30 mm.
The turbo inlet is 60 mm but fed with a 40 mm pipe.

So my question. Could an intake be too restricted for the turbo, causing it not to spool up properly and there not being able to build boost?

Please give me some advise! Thans in advance
I would think the turbo would still make boost regardless of intake restriction. Pressure isn't created by the turbo, but by load placed on the moving air. Like on a hydraulic system, the pressure isn't made by the pump it's made by the load on the hydraulic cylinders. The heavier the load, the higher the pressure. So by that logic a more restrictive intake would actually create higher boost pressure.

I would look into your crossover pipe system. Remember for every pound of boost you make, your exhaust side needs to hold that much plus a little more for turbine drag.
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