Engine/Transmission (1994 - 1998) boost question

[onestackdram]

I have a question, to which I am sure I already know the answer to but just for the Sh*ts and grins I'll ask anyway. I just got my guages installed and all working fine. But when I am running down the highway @ 2500 approx. 73/75 mph's my boost is sittin steady at 20-22 psi. (p. s. I have nv4500 and 4:10) If i drop the rpms below 2500 even around 2400 and lower my boost will stay between 14-16 psi. Now for those that are going to ask my egt's are pretty steady between 650 and 800 (rarely get over unless I am hammerin it). So my question is should I be running that high a psi at or over 2500 rpms? I do realize that if I am already that high that when I get my DDII's in I will have to step up in my housing. But Im just curious if I am already running to high and if so what can I do to lower it (w/o buying a new housing) until I have the money to buy one?



TIA

Russell

 

[C. Harlan]

when I had my stock HX35-12, I used to run about the same PSI's, at around the same RPM's, though I have 3. 54's. . Now that I have my PDR HX40, I flow about the same amount of air, but run down the road pushing 4-6 psi max, cruising @ 2300 RPM... I dont know how it will be with this new NV5600 I have, as I am patiently waiting on the return of my CON OFE from Peter, as I need the new hub put on to accomodate the input shaft on this big boy. also, cruising, I run ~500°-700° post turbo... I pull too much to run pre, so that's my reasoning for going post.



-Chris-

 

[illflem]

Don't know what you're after but the higher your boost the worse your fuel economy. Running down the road empty at 75 mph my boost is 3 - 5 psi but will hit 35 if I put my foot into it. Sounds like you have your wastegate disabled or cranked way up.

 

[cowboy up]

Originally posted by onestackdram

I have a question, to which I am sure I already know the answer to but just for the Sh*ts and grins I'll ask anyway. I just got my guages installed and all working fine. But when I am running down the highway @ 2500 approx. 73/75 mph's my boost is sittin steady at 20-22 psi. (p. s. I have nv4500 and 4:10) If i drop the rpms below 2500 even around 2400 and lower my boost will stay between 14-16 psi. Now for those that are going to ask my egt's are pretty steady between 650 and 800 (rarely get over unless I am hammerin it). So my question is should I be running that high a psi at or over 2500 rpms? I do realize that if I am already that high that when I get my DDII's in I will have to step up in my housing. But Im just curious if I am already running to high and if so what can I do to lower it (w/o buying a new housing) until I have the money to buy one?



TIA

Russell

I have the same setup and i only boost 7-10 psi at that rpm:--)

 

[esommer2500]

65 mph, 1900 rpms, flat, no wind = 0-2 psi



65 mph, 1900 rpms, flat, with good head wind = 7-10 psi



65 mph, 1950 rpms, uphill = 15-20 psi



3. 5 gears, NV4500 in 5th gear with the cruise engaged. A hard accelleration can yield well above 40 psi, which isn't good. I was hoping to address that issue this weekend, but never got around to it.







Eric

 

[JohnE]

I run similar boost readings to esommer2500 with my auto and 3. 54 rear end. My EGTs are usually under 600° and will climb to maybe 700° with a strong headwind.

My wastegate is disabled and I have a #4 plate.



Something is really wrong with your boost and slightly high in your EGTs.

First place to start is your timing.



I see you have stacks, but is the muffler and/or converter still in place?

 

[onestackdram]

As far as my stacks I'm running straight. I do have a the 3" downpipe still in, I just used a reducer to get to the 4". I realize that eventually I will have to get a 4" downpipe, but for now Im not to awful worried about it, as my egt really isnt that high. My main concern is the boost psi? Am I running so high at that rpm due to the stock turbo? or could it be something else?

 

[JohnE]

I don't think it is your stock turbo. I have the same turbo with a stronger plate and boost doesn't get out of hand even in 3,500 rpm range.



That's why I suggested timing. If your timing has slid it will increase EGT which increases boost.



Is your pyro probe pre or post turbo?

 

[johnjackson]

Something isn't right. 73-75 is what I cruise at all the time. (just below ticket speed) On flat hiway my boost guage reads 5-7 #. I have to boot it prety good to see 20-22. I have a stock turbo with the gate down prety tight. I can hold my 30# gage on the peg if I really keep my foot in it. Hope that helps.



John

 

[onestackdram]

I guess i should have been a little clearer on my driving conditions. I'm on the Kansas and Missouri line so I dont have too many hills but some. When I hit 20#'s it on a 'slight' to decent uphill or headwinds. If I am on flat or little to no headwind my boost will stay in the 12-16# range. My afc star wheel is turned foward approx. 3/4 of the way foward if not a little more. (I'm a smokeaolic).



My pyro is PRE-turbo, that was the general concencous on where to put it because of my pending 'BOMBs'

 

[JohnE]

TIMING

 

[onestackdram]

Is there a way to adjust the timing with out taking it to a shop. I have done such a thing on old gassers, but never a diesel. I realize that both are completely different, but I cant imagine that it can be that hard.

 

[illflem]

onestack, you'll need $200+ of special tools and these instructions http://dodgeram.info/tsb/1994/18-10-94a.htm