drilling out elbow to reduce boost?

[WadePatton]

I carried this over from 2G forum. No answers there yet. One guy said leave the vent alone, but that makes no sense--at least not yet.



Has anybody drilled on a "non-adjustable" boost elbow?



I'm going to real soon. Am I charting unknown territory? The whole point is that I have an extra elbow and too much boost on a 35.



+++++++++



I picked up a second boost elbow to play with, so I probably will do some drilling.



Questions: Which hole orafice to modify? Or exactly how does the vent to atomosphere play in this deal?



Isn't the vent aspect what you're playing with on the "T" and needle valve setup?



I'm not quite clear on the elbow system. The internal orafice is reduced from stock and a vent is added. My guess is that the restricted internal passage slows the wastegate response and the vent really limits the boost seen by the wastegate actuater. Thus more boost and more faster. (without getting into the fuel aspect of boost development)



I'm trying to stay in the efficiency window of the 35 to keep from superheating the air and loosing density--as well as preventing extra stress on the turbo and associated components.



And yes I have the itty bitty drills-they were made for carburetors.

 

[JR2]

Back in the days before elbows guys used to use a cheap regulator and set the press that way. You just plumb in into the hose to the wastegate and set it where you want it. I think this is essentially what the turbomaster system is also.



JR

 

[WadePatton]

first try

I found the orafice hole to be under . 022" and the vent hole to be . 030". I drilled the orafice to . 022" (smallest drill I have) and the vent to . 032".



Result: Making 39-40# instead of 42+ on initial runs-- once the road dried up and I could get some traction.



Next I may drill one or both holes out just a teensy bit more.



Anybody with an adjustable elbow tell me which passage is being altered on it?

 

[fj40charles]

Wouldn't it be easier to just get an adjustable elbow?

 

[WadePatton]

Oh, and I think the EGT's may be down a smidge. Hard to tell ambient air is cooler.



Yeah, Charles I could do that, but I'm sittin here with two aftermarket boost elbows and a perfectly good set of orafice drills and $0 dollars involved.



I just thought that somebody somewhere might have dealt with this before. And I love simplicity-less parts.

 

[Reddog1]

A modified elbow came with my #10 fuel plate. I put it on, and it raised my boost from 18 lbs. to 37 lbs. I blocked off the wastegate entirely, and had 38-lbs. boost.



This was done with a stock exhaust system (w/Cat) and stock turbo.



My next step is to see the boost change with a straight pipe.



I am trying to determine if I can go to a non-wastegate housing, it is substantially cheaper.



I am chasing EGT.



Wayne

 

[WadePatton]

DID IT!

My EGT's are a non-issue. From a dead stop to 90+mph before 13-1400F. Rolling into it from 60-70mph and I run out of road/R's before it gets warm. And getting the Boost back into the proper range will only help that.



Okay I didn't take time to measure this time, but I went up two drills on the orafice hole. (Previously (after the first two drillings) it would still build and hold 40psi. ) Anyhoo today I drilled it some more and with wet roads I could only get 36 peak and 34 sustained PSI.



Looks good. I'll measure it if anybody cares--wait a minute. [time passes]



. 028" should be what I wound up with on the orafice and about . 030 on the vent.

 

[Reddog1]

WadePatton



I am interested in what you are doing. I am having problems with EGTs. I cannot go from a dead stop to 90+mph before 13-1400F.



I have a 12 valve, so the EGT comparison between our trucks is probably very different. Your experiment with the elbow should apply to both our trucks.



Here is a thought for you:



At the turbo, a Needle valve followed by a “T”, with another needle valve for bleed and a hose barb for the waste gate. Now, you have total adjustment.



When you say “it would still build and hold 40psi” am I understanding correctly, that boost maxs out at 40#, and stays until you reach speed or let up on the accelerator?



Wayne

 

[WadePatton]

Yeah, somebody else has said use the tee and needle for full, even remote adjustment. I just didn't feel the need to hunt those parts and do the plumbing. I have a spare boost elbow and a set of teeny weeny drills.



Sustain means I wasn't just hitting the number and falling back down. On my test hill I can put it on my top number and hold it there for several seconds when in the NO DEFUEL mode. Otherwise I run out of load, road, or R's too quickly for a "sustained" number.



Here's exactly what I did clipped from a PM:



The drill set I used is a carburetor jet drill set. This particular one is a MAC tool job(MAC TOOLS TD3M) fashioned like an ink pen the 12 bits stored in the back and the business end holds the selected bit for drilling (by hand). The drills range in size from--oh, hell I'll measure them:

. 021

. 023

. 026

. 029

. 031

. 034

. 036

. 038

. 041

. 045

. 051

. 059 inches



I couldn't find any good info on which hole to drill and why, so I just enlarged them both-figuring that they work together, no?



I found the holes to be:

orafice (O) <. 021, vent(V) ~. 029 before I started. First drilling--O=. 021 V=. 031 no change.

next O=. 023 V=. 034 not much change.

today I didn't measure but went up two sizes on the Orafice only, which should be . 029, and chamfered the hole some with the largest bit. Now I have reduced peak pressure.



If you can find the teeny drills I suggest going slow like I did 'cause . 002 is a big percentage of . 020. and your ride may respond differently.



It's kinda neat to row uncharted waters on the CTD (somebody has done it, I just haven't found out who).



HTH

 

[Roger rodbolt]

Wade,

It's fun to experiment, I spend way too much time doing the same. It doesn't cost anything to adjust the rod on the wastegate. The elbow is just for folks that don't want to take the time to do the adjustment. Larry

 

[WadePatton]

ROD? Oh, well outta sight outta mind. Can I get to the rod with the turbo in place? I think I saw it when I had the turbo off.



I can R&R a boost elbow in about 3. 5 minutes blindfolded in the rain. Drill time not included.

 

[Roger rodbolt]

Wade,

Yes, you can get to the rod with the turbo on. No, I can't adjust the rod in 3. 5 minutes with my glasses on. I do understand the instant gratification thing, though . A boost elbow is a good sales tool for the folks that sell horsepower enhancement to the masses and they do work. Drilling out the orfice will delay wastegate opening to a point. Seriously, I'm a firm believer staying within the compressor map of the turbo. There a several reasons to do so and some of these aren't discussed on the TDR forums such as the stress our engines occur on the exhaust stroke due to extreme exhaust back pressure. Larry

 

[J.R. Adkins]

Larry,



Do you have the waste gate set up on your B-1? There are several members that are trying to do so. I think that a B-1 would benefit fro a WG.





J. R.

 

[Roger rodbolt]

JR,

I havn't considered a waste gate because I seem to be boost/horsepower challenged . I only see boost in the low fifties at the map sensor and my understanding that the B1 is well with in the compressor map at that boost. At what boost should the wastegate be set? I'm trying a set of Pier's 14 hole injectors and think that the B1 has more then met it's match... ... can't clear the smoke even at part throttle and mid forties boost.



Wanted to let you know that I was just teasing on the other post inregard to the 2800ft lbs on the ME clutch. I had heard that figure but only once from someone should know... ... ... if you know those guys they don't boast. Larry

 

[J.R. Adkins]

Larry,



I dont think that it will burn the fuel over 45-50 after that it is out of its map! The B-1 is one of the best daily driver single turbo that I have seen. The other is the hx-50 hybred from Haisley and Scheid! Man that thing spools!!



As for teasin, i can take it! I used to be a mad dog in my past life. My owner used to teas me with raw meat until I bit him in the *ss!! LOL





J. R.

 

[Roger rodbolt]

JR,

Thanks for the info, I am going to get the gauge out and check the drive pressure.



Regarding the teasin'... ..... ouch!! Larry