Twins problem

KingS

KingS

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Joined
Nov 29, 2006
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Hey guys I posted a question in the 94-98 section on my problem I'm posting here because alot of you guys read here and don't go through those sections.

Problem is twins won't spool like they should. They aren't terrible on the street but slow, considering if doing 45 50 mph stomp the pedal to the floor and by the time the turbo's really kick in I'm doing 80+mph when I get to 2000rpm which is the time they kick in good. If I hit the od button on then off so the truck kicks down it spools and is gone right now what is the fix? I don't want to lose fuel since I want to hit 12.0 with this truck.

It also won't spool on the dyno.

if you want to see how it runs ect. click on the link in my sig for on the strip and here are my dyno runs.

http://video.competitiondiesel.com/video/321db4a5-13cb-4b9b-a1a4-99ca00e0c13e.htm
http://video.competitiondiesel.com/video/6900940a-8f9b-4e65-914d-99ca00e1e1c4.htm

I forgot to clearify my setup I have JL. machining's 5x16 edm'd injectors his version of laser cut dv's and my dv holders have been punched out to the same size hole as my stock fuel lines.
I have #5 tst which at full fuel is alittle more then a #0 plate I measured this. 4GSK's And my hx 35 is stock except I took the divider out to allow wastegating of all 6 cylinders and the wastegate hole has been enlarge some, as well to help with taking pressure off the turbo once opened, and it is set up to stock open at 17 20 psi.
Sorry so long guys but want to get this figured out soon thanks.
 
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its all about tuning the top turbo, in this case the HX35. I used to have HX35/BHT3B twins. screw with the waste gate arm and the small screw (can't remember what its called) on the boost elbow. Test and tune til it works. 17-20 maybe a little low....


I had the exact same issues. I never really got it all set up right on my truck before I had other issues and sold the twins...but the new owner of my twins got it working in 3 days. I can give you his contact info if you would like...just shoot me a PM.
 
I'd say your not working the bottom turbo hard enough, you may need to add an external wastegate to get the 3B lit. I wouldn't block off the waste gate on the HX35 that will over work it and choke off your engine. If you could set the waste gate on your Hx 35 to start opening at 20 psi and wide open at 30 psi your engine should be moving enough air to lite the 3B. PDR can also machine a larger internal waste gate into the HX35 which may help.
 
I run an hx40/3b and have had the same problem. I ended up getting it to open the wastegate at about 25psi and like 973604x4 said shorten up the actuating arm to get rid of the wastegate flutter. The flutter comes from the restriction in the hot pipe due to the second trubo and actually tries to close the wastegate. What size turbine housing you running on the 3b? I have a 26cm and it is kind of laggy. How much boost are you seeing from the bottom? Total? When does the bottom start to light as compared to the boost at the head? Will I ever quit asking questions?
 
for boost I only have a gauge on the intake and I run 70 psi, I know the bottom turbo start to spin at around 10 psi but lights at around 20 maybe alittle lower I can tell this because I can here the bottom turbo start to whistle the boost gauge snaps faster then my rpm gauge once the bottom lights.

I have a 26cm also. I had a 32cm at first which didn't change the way it spools it just made the power smoother with the 26cm the 32cm though was more impressive on the street when it lit though it was more of a jerk and hold you back in the seat where the 26cm just sits you back in the seat smoothly and holds you there.

any more questions I can answer to help
 
I would play with the wastegate since thats free and see if you can get it tuned in a little more. I like the nitrous because it is instant boost.
 
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In a normal Twin setup using a Holset as the top turbo you either have to do allot of work on the wastegate or put an external gate in. The holset gates will not hold up under a high heat situation, once your to the point were the housing starts cracking the flapper arm will start to tweak, when this happens the flapper will not seal correctly and cause it to be a lag pig.

Set your gate(with regulated shop air) to crack at 25 and it should be wide open at 40, this seems to work well. One other thing I can add is you need work on you AFC as you have too much bottom end fuel, you can get a stiffer spring, do the washer flip (if you haven't) and set up you max fueling(with shop air again) to about 40 psi, do so will allow you to get up on the chargers quicker.

Take your cold pipe and tap it in the back for a gauge and see how much boost the bottom turbo is putting out, this is a must for tuning and will tell you allot.

Jim
 
all right I will do that and the waste gate adjusting how can I adjust the hx 35 can I do it with out a boost elbow last one I had I would adjust it and the screw would vibrate and fall out in the first mile.

Jim, your honest opinion should I keep the twins or go big single?

I have adjusted the afc the foot doesn't even move until 10 psi of boost. Only thing I can do that I know of is slide the housing forward, to cut fuel back more but if I do this will it move out of the way enough once the arm moves back to allow full fuel on my #5 or will I have to grind the back of the arm or something to allow it to slide back more so the gov foot hit the plate that is full forward?
 
Ok Update guys I have the waste gate set to 25psi now noticeable difference but still can't get on it hard hard I can get about a half throttle take off and she response pretty good but more then that is still bogs the truck so next step is what.

Bigger top turbo
Bigger exhaust housing on top turbo
slide afc housing foward to cut fuel back more at the start.
If this option read reply above I was waiting to hear back from Jim on that one, if the foot would move out of the way enough or would modification need to be done to allow full fuel if afc was slide foward if modification is needed who is close to me that can help me fine tune the afc guts. I even after reading how, don't understand the mod's for the afc I am a watch and hands on learner not a read and learn.

Thanks so far guys she is getting there.
 
mine when at 10psi response the same as that if not faster to 70psi my problem is the part until it gets to 10 psi and 1800 to 2000 rpms.
 
i think you have too much fuel, you probably put out the fire, on the bottom end (before turbos spool)

i like the afc housing slid completly back (toward the cab), with the smoke screw out all the way... cuz you have big dv's, big injectors, and big dv holders! once you do that, (if you feel like your missing fuelk on top end, mod the afc, like jim fulmer said, i have pics somewhere, if yopu search afc modding or something, you should dig up somthin
 
KingS said:
Only thing I can do that I know of is slide the housing forward, to cut fuel back more but if I do this will it move out of the way enough once the arm moves back to allow full fuel on my #5 or will I have to grind the back of the arm or something to allow it to slide back more so the gov foot hit the plate that is full forward?
Click to expand...

moving the afc forward adds fuel move it toward the cab to decrease I also did the washer flip and ground off the small lip on the new front washer and I was going to do the grinding of the backside of the arm but I found in my own experimintation that there is no gain from doing this when you flip the washers they still hit the housing before the back of the arm will contact the housing so at 35#'s on mine I had full arm travel (washer/diaphram hitting housing) and still had a small gap between end of arm and housing.

P.S. Ph4tty, I know have boost envy.. Thanks.. :D
 
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Ph4tty said:
This isn't my truck, but its a 35/3b on a 12v.
Click to expand...


The video says 24v...?

I have seen a couple of people with the external waist gates that get dumped in right before the bottom turbo...
 
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