How To: Build your own 4.0L turbo Cummins (Beware...170+ pics)

[RedChuck]

im excited to hear it. from the vids it sounds normal

 

[Mesh]

Very cool, I hope you find some time to get to the dyno.

 

[Boostwerks.com]

Very cool, I hope you find some time to get to the dyno.

Same here. Right now it's not so much the time, but the $. I manage a steel fab shop for my day job and had to take a fairly substantial pay cut about a month ago. We also had to lay off about 50% of our shop as well so I'm just happy to still have a job.

Damn economy. :smsoap:

 

[Finaltheorem47]

Damn your XJ hauls ass.

Thanks for inspiration and motivation!

 

[Jposses]

man the AEM unit is great...is very simple...and the jeep PCM is really easy to tune up...

the turbo i have is a GT3582R twin scroll and begin to charge psi at 2.800rpm....

and also i install the power tech tunning programm and when the engine goes to 5750RPM is incredible...uncontrolable charging only 7psi....at 11psi is undriveable...

The AEM is the best upgrade i done...just need to learn something more but i have to thank you for that..

JP

 

[asp]

A diverter valve is really designed for vehicles with a MAF sensor (such as most subaru's and mitsubishi's). Most of these vehicles will get a CEL if a BOV is installed before (or after even) a MAF because the ECU thinks the sensor just failed.

The BOV will only open when the throttle plate suddenly closes so the turbo doesn't surge and destroy it'self. In this case the compressed air is useless anyways. I hope that makes sense?

Yeah, I was familiar with how both of them work. I also knew that putting a BOV on a DV'd vehicle would make the ECU go nuts. I have a MKV VW GTI with the 2.0T and I know they say never to put a BOV on those or Subarus. I guess my question is why not recirculate the air that's already compressed to sort of give the turbo a bit of a jump start? Both valves release the pressure, but one puts it back into the pre-turbo intake ducting. It sounds like part of the reason you went with the BOV is that XJ's don't have a MAF... but I can't see a DV hurting an un-MAF'd engine.

Either way, awesome work and cool videos. Looking forward to ones with better sound.

 

[bigdaddyjlove]

Does anyone know the math to figure the HP at the wheels? Just curious.

 

[DanMan2k06]

and I know they say never to put a BOV on those or Subarus

My school is in the same building as the Suburau National Training Center, and that's all I hear leaving the parking lot.... vrooooooooompssssss

 

[Glacialbass]

Yeah, I was familiar with how both of them work. I also knew that putting a BOV on a DV'd vehicle would make the ECU go nuts. I have a MKV VW GTI with the 2.0T and I know they say never to put a BOV on those or Subarus. I guess my question is why not recirculate the air that's already compressed to sort of give the turbo a bit of a jump start? Both valves release the pressure, but one puts it back into the pre-turbo intake ducting. It sounds like part of the reason you went with the BOV is that XJ's don't have a MAF... but I can't see a DV hurting an un-MAF'd engine.

Either way, awesome work and cool videos. Looking forward to ones with better sound.

The reason that the Audi/VW engines use a DV and not a BOV is not because they use a MAF, it's becuase of where the MAF is located, post/pre turbo.

 

[asp]

How are the stock internals holding up to 8psi? I did some reading here and on PBB. The general consensus was that the much more than 6.5 psi will eventually lead to breakage (be it a cracked head, thrown rod, etc).

 

[Glacialbass]

How are the stock internals holding up to 8psi? I did some reading here and on PBB. The general consensus was that the much more than 6.5 psi will eventually lead to breakage (be it a cracked head, thrown rod, etc).

He's at 5280+ feet in elevation. Because of that, he can run more boost and get away with it.

 

[Boostwerks.com]

How are the stock internals holding up to 8psi? I did some reading here and on PBB. The general consensus was that the much more than 6.5 psi will eventually lead to breakage (be it a cracked head, thrown rod, etc).

They're holding up just fine.

First of all, Boost doesn't kill an engine. Detonation and excessive power will. For example, the 8psi I'm running is about 50% more air flow from the turbo than a M90 roots blower running at the same 8psi. Because of that the turbo is simply flowing more air @ that pressure level than the blower. Simply put, thats why larger turbos are capable of more power than smaller ones... easy enough right?

On the other hand, the power level that I'm running I don't consider "dangerous" for this particular motor AS LONG AS it is tuned properlly and detonation free. Forged internals however will allow for higher power levels and will sustain mild tuning discrepencies/detonation without damage. This is why I put such an extensive push for good tuning and engine management. If done correctly, most factory motors can and will last a very long time with boost. Case in point...our 11:1CR 1.6L honda has dyno'd over 400whp and lasted the past 4 years on stock internals.

 

[asp]

They're holding up just fine.

First of all, Boost doesn't kill an engine. Detonation and excessive power will. For example, the 8psi I'm running is about 50% more air flow from the turbo than a M90 roots blower running at the same 8psi. Because of that the turbo is simply flowing more air @ that pressure level than the blower. Simply put, thats why larger turbos are capable of more power than smaller ones... easy enough right?

On the other hand, the power level that I'm running I don't consider "dangerous" for this particular motor AS LONG AS it is tuned properlly and detonation free. Forged internals however will allow for higher power levels and will sustain mild tuning discrepencies/detonation without damage. This is why I put such an extensive push for good tuning and engine management. If done correctly, most factory motors can and will last a very long time with boost. Case in point...our 11:1CR 1.6L honda has dyno'd over 400whp and lasted the past 4 years on stock internals.

Glad your engine is doing well.

If you feel this is cluttering your thread, I apologize. Feel free to have a mod move it. I do appreciate your help as I learn.

I agree that detonation and excessive power is what causes engine failure. So, assuming that the AF ratio is proper and the incoming air is cool enough (via CAI, intercooler, meth, etc), you won't get knocking. That's something that a good tuner will account for in configuring an engine. I couldn't agree more.

Here's where you lose me: If the intake air is at 8psig in a SC system or a TC system and the systems are identical, how will a TC flow 50% more air?

Along those lines, more psi = more gas to maintain proper AF ratio (but you need to account for that in the pre-intake cooling (meth, IC, etc) because the intake air will be hotter). Excessive power can be generated by too much boost with proper tuning. No arguments there, right? So commutatively, more boost = more power; we all get that. Continuing in that direction, how much power is too much power for the 4.0 with stock internals and how much boost is required to get there? I'm not actually looking for an answer, but using the question as a tool of conversation... (but if you happen to know the answer, I'd be ok with that :laugh3

Reading that, it may seem like I view boost as a sort of magical power maker. I know it's not and that each and every forcfully inducted engine will behave differently depending on the components used, have differently shaped power and torque curves, etc.

Now I'm back with you: Larger turbos make more power because the exhaust gas flows more freely through the turbo and can spin a bigger turbine which can compress more intake air. I'm familiar with forged internals and their benefits too.

Once again, thanks for your help.

 

[Boostwerks.com]

I agree that detonation and excessive power is what causes engine failure. So, assuming that the AF ratio is proper and the incoming air is cool enough (via CAI, intercooler, meth, etc), you won't get knocking. That's something that a good tuner will account for in configuring an engine. I couldn't agree more.

AFR is important, but proper timing is more important. Too much timing and you'll get preignition/detonation, too little and you'll melt pistons/valves. It's up to the tuner to be able to read the engine and tune accordingly.

Here's where you lose me: If the intake air is at 8psig in a SC system or a TC system and the systems are identical, how will a TC flow 50% more
air?

Without getting a masters in fluid dynamics, the easiest way to visualize this is understanding the relationship between pressure and flow which is exactly what a typical turbo compressor map will show you.

For any given pressure ratio, a compressor (turbo or SC) will flow a specific amount of air. The larger the compressor, the higher flow. Just like how a 6.0L V8 will flow more air and produce more torque than say a 2.0L 4 cylinder simply due to it's physical size.

Along those lines, more psi = more gas to maintain proper AF ratio (but you need to account for that in the pre-intake cooling (meth, IC, etc) because the intake air will be hotter). Excessive power can be generated by too much boost with proper tuning. No arguments there, right? So commutatively, more boost = more power; we all get that. Continuing in that direction, how much power is too much power for the 4.0 with stock internals and how much boost is required to get there? I'm not actually looking for an answer, but using the question as a tool of conversation... (but if you happen to know the answer, I'd be ok with that :laugh3

There are simply far too many factors involved to give a specific answer, but the general rule of thumb I like to use is that an increase of 100% over stock is about the maximum you'd want to go for any factory engine. However if you use my 1.6L honda in this equation though it should have blown up at 200whp, but does just fine @ 400. Every engine is different, it's really just up to how much risk your willing to take.

Now I'm back with you: Larger turbos make more power because the exhaust gas flows more freely through the turbo and can spin a bigger turbine which can compress more intake air. I'm familiar with forged internals and their benefits too.

Once again, thanks for your help.

It sounds like you understand just fine. It's all about having fun, and turbo's are absolutely my crack. I've been addicted since I was 16. :confused1

 

[asp]

AFR is important, but proper timing is more important. Too much timing and you'll get preignition/detonation, too little and you'll melt pistons/valves. It's up to the tuner to be able to read the engine and tune accordingly.

Without getting a masters in fluid dynamics, the easiest way to visualize this is understanding the relationship between pressure and flow which is exactly what a typical turbo compressor map will show you.

For any given pressure ratio, a compressor (turbo or SC) will flow a specific amount of air. The larger the compressor, the higher flow. Just like how a 6.0L V8 will flow more air and produce more torque than say a 2.0L 4 cylinder simply due to it's physical size.

There are simply far too many factors involved to give a specific answer, but the general rule of thumb I like to use is that an increase of 100% over stock is about the maximum you'd want to go for any factory engine. However if you use my 1.6L honda in this equation though it should have blown up at 200whp, but does just fine @ 400. Every engine is different, it's really just up to how much risk your willing to take.

It sounds like you understand just fine. It's all about having fun, and turbo's are absolutely my crack. I've been addicted since I was 16. :confused1

Funny you should mention a background in fluid dynamics. I have a BS in ME and my favorite class was thermo fluids. :laugh:

Yeah, I've spent some time staring at compressor maps and thinking. I think I understand how they work, but the trick will be getting each piece to fall where you want them to in practice. It's all dependant on the particular loading (read: throttle & rpm combo +/- incline)... Is it best for those to fall at WOT or is it ok for the compressor to approach the surge line at WOT? Conceptually I know that surge occurs when the pressure in the intake manifold is significantly less than the pressure between the compressor and the intake manifold... (like when you let off the gas sharply, that's why we need BOV's and DV's)

Boost is undoubtedly a lot of fun. I think the thing that confused me was just your statement about superchargers flowing less air per size of hardware (smaller turbo will push more air through than a similar size SC). I'm on the same page as you now :thumbup: I'd like to think that I know turbos better than superchargers.

Wow, 100% over stock is quite a lot. I'm hoping to get 50% more haha. This will be the first engine that I'll have tuned... Needless to say I'll be keeping it safe at least at first. If I get confident in my abilities I'd do something like switch to a smaller pulley and retune.

I'm sure I'll have more questions as I get closer to the electronics side of things. Bracketry and piping is the easy part. Thanks again.

 

[ChargerX3]

How are you going about measuring knock?

 

[Boostwerks.com]

How are you going about measuring knock?

Reading the plugs and proper tuning. As long as nothing is drasticly changed with the motor, there isn't a big need to worry about it after tuning.

 

[streetxj]

Awesome setup! :05of5:

 

[ChargerX3]

Reading the plugs and proper tuning. As long as nothing is drasticly changed with the motor, there isn't a big need to worry about it after tuning.

Yea, but you cant get real time accurate readings that way. It would pay to purchase an aftermarket setup that logs knock. Im very tempted to try this our myself with a few modifications.

 

[Boostwerks.com]

any tuner worth their weight will tell you that reading the physical signs and proper load based dyno tuning, is more effective than reading the "noise" a sensor is telling. IMHO, If your getting any significant knock readings from the sensor it's either A. Telling you the same story as reading the plugs or B. To late as the damage has already been done (improper tuning).

Keep in mind that for a knock sensor system to work properlly, the sensor must be "tuned" so that normal engine noise is not picked up as knock. However, even the best knock systems will still give false positives which can lead to tuning mistakes which may cause other problems. This is why a lot of aftermarket ECUs/tuners commonly do away with the knock sensor.