Engine/Transmission (1994 - 1998) Not enough Boost

[dwadley3]

I own a 1996 CTD it has a # 6 torgue plate-16c. m. and Piers HX35 Turbo updrade. AFE Stage I-Pro 7-4 in turbo back exhaust and TAG. Iam only getting 22lbs of boost. I bought this beuaty 6 months ago. I added the exhaust and the TAG and AFE. It runs well and I get very good mileage at 23. 5 with no load . It also has a gear vendor in it. I am thingking it should get a higher boost with all this Mod bomb on it. anyone care to advise whats up

 

[ndurbin]

You might need to check all your boost connections out to make sure their tight.



the afe pro guard 7 lowered my boost PSI by 2lbs. bigger exhuast might also have played a role since the exhuast side turbine wheel doesn't have as much resistance.

 

[dwadley3]

Thank you for the reply. Does a boost elbow help with performance. I was thinking around 30 lbs boost would be right.

Assuming no leaks should I consider a boost elbow.

 

[ndurbin]

I don't have any exprience with boost elbows sorry.



Nathan

 

[bmoeller]

Do you have a boost elbow with an allen head screw in it? If you have the stock one, it won't allow for more boost than what you have.



May need to swap the 16 housing for a 14. The factory 12 may be fine if the EGTs aren't to high with it. When the housings are bigger than what is needed, they reduce performance (ie, less boost and sometimes higher EGTs)

 

[dwadley3]

The performance of the turbo is ok . It spools up quickly and I get at about 1150 EGT pulling a good grade with my camper and boat in tow @ 65-70 mph. I dont know a boost elbow from my elbow. Just thought I should check into this. It would seam alot to go thru to swap out all this. I might call piers and have them give me a clue on this rig

 

[JGheen]

I don't think a boost elbow would help. My guess is the 16 cm turbine. Try going back to the 14cm or even the stock 12 and see what it does then. I am making almost 40 psi with my stock HX-35, a 14cm wg turbine and a #10 plate. I am running some off the shelf custom nylon air lines for boost actaution to the AFC and wastegate.



Not sure, just my guess.

 

[dwadley3]

Thank s for the tip. Ok lets say I go back to a smaller turbo -Iam I going in circles given what has already been bombed to enhance performance. The upgrade turbo is an expenive upgrade. Does a smaller trubo mean some type of advantage over the bigger turbo with bigger blades to pull or push more air not less. The logic is swirling in my brain.

 

[bmoeller]

I'll give you an example of what happened to me on one of the semi trucks I drive.



Mack CH613, EM-6 300 backed by a straight 5spd transmission, no splitter.



Had to replace the turbo when it went out. They gave me one with a larger turbine housing since the one I needed had to be ordered. Went and put it on since we needed to use the truck.



This was the winter time also. 'Bout 10-20* outside temp.



Stock turbo- 22# max boost, 800-850* EGTs (post turbo).



Bigger housing- 17# max boost, would climb up to over 1000* very quickly. Was a real dog. Took forever to pick up speed in O/D.



Day later with correct turbo, back to normal.

 

[JGheen]

Another example I recently learned is that the smaller the port the more velocity you will get hence faster moving air. I would think the EGTs would be a lot less becasue it is a bigger volume but the EGTs can get big because your stuffing that larger volume with more heat and being it has less velocity than the smaller turbine the air is moving much slower through it causing the EGTs to rise quicker. I hope that made sense... . check out my thread on "Boost question" in this same 12v forum... ... my questions were answered well and I was on the same track just confused like you about some things.

 

[dwadley3]

Well these case examples do anwser alot of puzzeling questions about certain combos of intake, size of turbo, exhaust and then the result as to spool up and effect to EGTs. My egt heat sensor is in the maifold and Iam getting WOT up a grade with a moderate load showing 1150 . Is this okay or should I scrap this 16 cm and go to a 14 and figure this should put me mid way and lower my egt with more pressure too move air flow faster. Net result would be more power,lower egts at wot. Or Psss on the whole thing-What ya think. Hey you guys are great, everyone contributes and this forum really helps us all out.

 

[dwadley3]

JGheen I will study your treads on this subject . Sounds like some of those treads you got going on this will help me get the picture.

 

[JGheen]

Originally posted by dwadley3

Well these case examples do anwser alot of puzzeling questions about certain combos of intake, size of turbo, exhaust and then the result as to spool up and effect to EGTs. My egt heat sensor is in the maifold and Iam getting WOT up a grade with a moderate load showing 1150 . Is this okay or should I scrap this 16 cm and go to a 14 and figure this should put me mid way and lower my egt with more pressure too move air flow faster. Net result would be more power,lower egts at wot. Or Psss on the whole thing-What ya think. Hey you guys are great, everyone contributes and this forum really helps us all out.

Thats good that your exhaust thermocouple is pre-turbo, it's best that way or you would be doing a lot of calculating in your head. 1150* EGT is not bad at all, I would be worried if you saw 1350*+ for more than 20 or 30 seconds at that temp..... piston meltdown. But take into conisderation that when you reach those temps for a split second it is Ok cuz that temp is not exactly piston crown temp which is where meltdown comes in. If you saw 1300 or even 1400 for a couple seconds while accelerating hard it should be ok, just don't let the engine hang at those temps for more than that..... IMO.

As for the turbine swap, I would go back to the 14 cm housing and see how much boost you'll get, you should see at least 5-10 more psi and about a little less on the EGTs but they will still get hot. But don't scrap the 16cm, save it for when you have mucho fuel consumption.

 

[JGheen]

I think you stated this already but where is your wastegate actuated off of?? The AFC housing or the compressor side of the turbo?? Is there a line going form the AFC across the engine to the wastegate actuator?? Just curious.....

 

[dwadley3]

I believe its the AFC housing. The turbo doent have one of those things sticking up from it. Would that be the actuater. Not sure of this device. The original owner pointed it out on the other side of motor driver side. I think it has a spring set up

 

[Rams-n-Hogs]

Have you checked the AFC housing to see if it's all the way forward, and the starwheel is turned towards the front of the engine? I think this has an effect on boost, since it affects fueling. Just another idea. Also, I would say get a boost elbow, if you don't have one. The other question I have is about your plate. I'm not an expert here, but I thought the #6 was designed for auto trannies. I used a #10 with a 16cm, non-wastegated housing on my stock HX-35, (before the injectors), and didn't have any problems with boost. I would call Piers, or TST, and ask them about that.



Jim

 

[JGheen]

I'm gonna second that comment, Piers will have all the answers but make your questions count, cuz he does have a business to run.



Oh and BTW, the actuator is the small canister looking thing that is attached to a bracket off of the turbine housing. It has a little nipple on it that goes up through one of the spaces between the exhaust ports and accross the engine to the AFC housing. It just opens the wastegate when peak bolost is achieved to prevent it from over boosting.

 

[dwadley3]

Thanks friends . I am going to print all of these posting and get this in the hands of an expert. I live in Everett Washington- I can get up to BC where Piers is located. I would be real interested in there prescription or what they recommend. This all has been very informative.

 

[dwadley3]

Rams-N- Hogs your points I will take to piers. Sounds like a logical question on the Fuel plate. I am very sure of the # 6 plate. The prior owner was an attorney and he really kept good records. I have the reciept on the uprgrades.

 

[Car_nut57]

Boost

If you have not done anything with the waste gate maybe you should modify the stock one or install a Banks Big Head to get higher boost pressure.