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.

https://www.homemadeturbo.com/attach...ine=1352319705

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)

https://www.homemadeturbo.com/attach...ine=1352319705

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).

https://www.homemadeturbo.com/attach...ine=1352319705

https://www.homemadeturbo.com/attach...ine=1352319705

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

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.

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?

Ok a short update.. I've checked the wastegate and it holds vacuüm.
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)

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.

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?

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.

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?

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.

I still would presume that when not enough air can enter the turbo (too small inlet), there is to little air to be pressurised.

in other words, not enough air can enter turbo or even more importantly the engine, therefore not enough load can be put onto the engine (lack of power), creating enough pressure in the exhaust system to spoolup the turbo

remember that at WOT I still read a 5 hg vacuum on the gauge, while normally it would / should be close to 0 (off boost)...

About the crossover pipe system (I pressume my exhaust manifold) do you think that the end pipe (just before the turbo is to big?

For some reason it completely slipped my mind that you are running a draw through setup. In that case you are right. If a turbo isn't supplied enough air, it can't pressurize it. But I think it would take a pretty strong restriction to make that happen.

I really should have taken another look at your build before posting. Is the turbo plumbed to both cylinder banks? I assumed you were running a typical crossover pipe system that V style engine usually uses. Where you have a conventional manifold on one side, and the other has the turbo mounted on it and a typical outlet on the bottom. Then you have a crossover pipe that attaches the two. Because of all the connections they're prone to leak.

I don't think the pipe size would have much affect on boost. Might introduce a bit of lag if anything.

In fact, I'm running the turbo of a single bank. That might seem odd, but Saab cars used this in the past with good results.

I figured that the TD04H-13C which was used on a 2,3 volvo engine is sized correctly for one bank. Because my engine is a 5.2 L / 2 (only exhaust gases from one bank) = 2.6 (spoolup will be even quicker than on the volvo's)

This would mean enough exhaust gas to run the turbo. (Why not use both banks, I hear you think. That's simple, in that case the turbine spool up is way too fast, causing it to boost almost all the time, and therefore killing economy and driveability).

For balance,
My better flowing homemade exhaust manifold + turbo (creating a exhaust restriction) on one side, and the already bad flowing stock manifold on the other side, should balance things out a bit...


Also I had a look at the compressor map before. and at 4500 RPM it should be able to flow approx 360 cfm (max of turbo), therefore giving me 210 HP (now it is only 150 max).

So keeping that in mind, If I obstructed the intake to much, lets assume at least the half, It could only flow 360 / 2 = 180 cfm

180 cfm with my engine would give me approx 70 hp, which causes my car to feel and drive like ****.

My guess therefore the problem is on the intake side! Which also explains the high (5 hg) vacuum at WOT.

Does any one agree with this reasoning, let me know!

i didnt see anything posted about fueling. did you add a fuel pump and a boost reference rising rate fuel pressure regulator? do u have an wideband afr gauge installed? whats the cfm rating on your turbo? if your turbo is too small your engine maybe breathing more air than the turbo can produce. on a large engine like that two t3 turbo or one t4 turbo would work great. the volvo turbo maybe too small........

i went on squirrel performance. they have a turbo calculator. i punched in some numbers with your engine and your turbo and it doesnt look good.

https://www.homemadeturbo.com/attach...ine=1352756883

I did the same, I've checked things beforehand,

My car has an army specific cam, which generates a lot of torque, with not a lot of HP
Redline = 4000 rpm
max power already at 2500 rpm

Checked the carb again, that's a 285 CFM 2bbl Carter carb.
The turbo can breath 360 CFM, so therefore should be big enough

No additional fueling system needed, due to the drawtrhough setup, carb will adjust accordingly, and above all I'm running an Impco Mixer (originally designed for FI) capable of feeding 7L + engine's (just turn the power knop to fine tune ;)

Again, I'm not looking for huge power, only good economy and additional torque for towing and offroad use

your turbo map maybe affected by the turbo only being run by one bank instead of two so less rpm in the turbo will be created causing less cfm produced by the turbo compresser. since that turbo is small for the engine it will need high turbo shaft rpm to create boost. 285 cfm carb seems a bit small for a 318 v8 engine.

sorry thought i read blow through instead of draw through. try running the turbo through both banks. if that doesnt fix it then i think a larger turbo and running it through both banks would solve your problem.

Busa, You might be right, however I was already working on a different intake, so that I will finish first. Having High Vaccuum at WOT means a restriction afterall. So offboost it would be nice to have close to 0 vacuum when needed...

The 285 CFM carb is indeed SUPER small, yet this is an old army trick. Fit large engine's with small carbs, and therefore limit the power the trucks can make. This way, it would be very hard to kill an engine due to abuse.

If the modified intake doesn't work, I'll try a crossover pipe (at this moment the goal is to create a bolt on package, without the need of modifying the original exhaust system!)

Yet looking at the whole setup it should work (if not to much restricted), The Turbo is measured at 360 CFM with the volvo motor (2.0 - 2.5), so the exhaust flow of such a motor should be equal to half of a V8 (5.2 L/2 = 2.6).

It possible has a higher turbo lag, due to the larger manifold it has to fill, yet I'll be running only 7 PSI, so that shouldn't be a problem I imagine...

I'll let you know how things worked out! Hopefully this weekend I'll be able to test my new dropdown tupe style inlet with 60 mm inlet size (matched to turbo).

hi Laurens, I think what you need to look at is the different size of the turbo sides you are using. The turbine does indeed have to be sized for the 2.6 litres of your trucks single bank of cylinders. However your compressor is having to flow and compress enough air for the entire 5.2 litres of the whole engine. This is how Saab did it- their compressor was gigantic compared to the turbine side. The reason you are getting oil in your pipework is the Volvo turbo doesn't have oil seals on the compressor- it was fuel injected so therefore blow thru- no vacuum was applied to the compressor seals. the carb is applying huge vacuum and sucking the oil out past the oil deflector. Hope this helps you out! love to see the beast going right.

Oké another update,

I've fitted the new homemade intake dropdown tube. It solved a bit, now at WOT I reach 1.5 Hg instead of 5. This seems to be about the same I got without the turbo setup. In that case, I've resolved the intake restriction problem, however still NO BOOST... Regular power though (maybe even bit better at low RPM)

I know the turbo is small, and I do run it from that single bank, but still I would expect some boost...

I can't do a leak test at the moment (compressor in the garage broke..) but it must be a major leak if it would cause no boost at all, Right?

So to put things simple,

I should see some boost (how little it could be) with this setup right! Or could the setup be so wrong that It will not boost at all?

I did replace the wastegate with another (adjustable one, that was laying around). And still have the CBV blocked off with a plate...

I'm also not sure I'll be adding the crossover pipe soon, as I have to get the car MOT'ed before December...

Any thought on why I don't get ANY boost, and If I should expect even a little boost with this system....

I read stories that the 13C turbo was able to boost the volvo to 18 PSI on the 2.3 Liter, so 7 PSI should be about the same for 5.2 L right?

Any thoughts again? (I'm not ignoring the previous suggestions! But due to time limitation I'm probable not able to create/buy the necessary parts and willing to cut up the original exhaust system before MOT)

crossover tube will solve your problem. the turbo isn't sized properly to use just 4 cylinders to compress enough air for the v8. either get one of the aforementioned turbo's off the saab, or run your crossover pipe for the turbo you have now.

Another update,

Sorry for the late update, been really busy getting the truck ready for MOT.
Long story short, I removed the complete Turbo setup for now. I don't have the time right no to modify the system to work properly.

I do however have a new plan. I'll be upgrading my Offroader (on the trailer in the picture), and plan to add this turbo setup to that (also DodgeW200 ex army truck). This time I'll be using a crossover pipe in order to get the turbo to spin fast enough.

It seemed to work on the other truck, but not enough flow to build boost though... I do also have another 13c turbo, So if I feel like it, I might go twin turbo afterall...

All of you, thanks for the helpfull replies, I'll give an update when something changes!! (might take a while though..)