Engine/Transmission (1994 - 1998) How Much Boost?

[PKemp]

I have an old question. You can see below what i've got in here. I have my boost gauge connected to the boost port on the side of the intake manifold as instructed by DiPricol install sheet. 0 boost at idle and about 13lbs at WOT.

#6 plate in stock position, star wheel about 3/4 turned in, no smoke at all. Stock timming, stock gov springs. Stock pump and injectors. She runs pretty good, good acceleration. Tops out right at 80mph. Pyro tops out at 900 deg (pre-turbo). Does the boost sound right to you?

 

[boondock]

Should be making around 18-20 stock, with more fuel from the #6 you should be making more than 20. I make 31 with a boost leak. With my #10 I should be 32-35. You have a leak or something is wrong...

 

[98rammer]

you may have had the plate back a little too far, though i doubt it. 1/8" makes a big difference in power usually. the lever adjustment procedure may need to be done (check piers' website). also, your star wheel is 3/4 of the way "in"? towards the front of the truck or the rear? it should be halfways to full forward towards the front of the truck.



tighten all of your intercooler boots... . also, cehck to make sure none of them are chafing against anything. a pinprick can leak at high boost so it really doesn't take much.



Tom

 

[fishjack1]

Pat - That sounds kinda low - with a TST Kit ONLY I could get about 30-36psi at WOT on my stock turbo.



I guess you have the brass boost controller installed on the turbo that came with the TST kit?

 

[Woodenhead]

Check the line and fittings for the gauge itself. Sometimes the line can get pinched or get a leak and give a false reading. If all else seems fine and power is still strong than this may be a possibility.



Mike

 

[98rammer]

yeah, as woodenhead said, if you tighten the cup too tight, you can turn the ferral inside and pinch the hose.

 

[PKemp]

Okay, I need to take the A pillar apart and check the connections on the gauge.

The star wheel is turned in towards the engine. I didn't see any chaffing on the intercooler hoses and the clamps are tight. I do have the brass boost control elbow that came with the TST kit, its connected in the line behind the AFC housing, has an allen screw in it. Whats that for? I haven't done the lever adjustment but the #6 plate is in the same position that the stock plate was. What happens if I move it?

 

[Woodenhead]

The boost elbow works by fooling your wastgate into thinking there is less boost than there really is. To do this it has a small orifice that leaks a little bit of air out of the line and restricts the air going to the waste gate. This way even though you have say 30 psi pressure in you manifold the waste gate may see only 15psi so it won't open. (I'm taking a flying guess at the numbers here). The allen screw in the boost elbow is used to calibrate the orifice in the elbow, it is recommended not to mess with the screw.



If you move the plate forwards (towards the front of the engine) you will get more mid-top end fuelling. The AFC spring and screw control how much boost you need before the governor will let more fuel into the engine (pre boost fuel). A stiffer spring or tightening the one you have by turning the screw towards the back of the motor will require more boost to overcome the spring and create a little more lag in the bottom end as well as reduce smoke. A weaker spring and or moving the screw towards the front of the engine will mean less boost to over come the spring allow more fuel sooner giving a faster turbo spool up but also more smoke. Adjusting the screw and spring won't change your max. boost pressure.



I hope I've got this right, if not someone please correct me.



Mike

 

[PKemp]

boost

Well I took all the boost line connections apart to and at the gauge and no crimping or problems with the fittings engine side or gauge side and no leaks in the line. But still boost at WOT is only 12 to 13 lbs. What am I missing?

Should I take the intercooler boots off and check them off the truck?

Any suggestions? Could the gauge be bad? I have pretty good power.

 

[TrqMonster]

Boost

When I installed a #11 and the new boost control elbow I went from about 24 PSI to like 32 or so. It does say not to mess with the allen adjustment screw on that elbow. Maybe at some point your allen screw got turned or perhaps it didnt come to you with the correct setting. That is where I would look next, I wouldnt assume it is correct 13PSI is really low.



Another question though: How much boost did you make before you installed the kit? or did you install boost gauge after the Plate/boost fitting?

 

[Woodenhead]

Even if the allen screw is messed up, aside from maybe causing a small boost leak at worst I should just cause the waste gate to act as it normally does and open at 20 psi or not open at all. (I think)



Mike

 

[Bob4x4]

There are a couple of things I haven't seen mentioned yet. #1 have you checked the wastegate actuator for a leak?#2Have you checked the AFC itself for a leak?#3Have you checked fuel pressure?





Bob

 

[PKemp]

The gauges were installed after the plate so I don't know what boost was "pre-plate".

I havent checked the wastegate, or AFC for leaks, or fuel pressure. It does run pretty good so I figured fuel pressure was okay (I don't have anything to check fuel pressure). I'll work that out and check all of that and report back later.