GreenGiant2 Posted February 23, 2016 Share Posted February 23, 2016 Was wondering if any one knows what the boost pressure should be on a bc 350 . i have had the pump set at 405 hp and want to start playing with it. before i go and start switching things i want to have my ducks in a row. just installed a boost gauge to see whats up. i have a new turbo and want to see difference. also will be installing a pyro in truck. i do have a pump with a clp code of 903 that is set for 190 injectors which is allittle big for me now. 903 cpl is for a 444 cummins. my current boost is about 22 psi. any ideas. Quote We the unwilling, Lead by the unqualified, are doing the impossible, for the ungrateful. Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/ Share on other sites More sharing options...
thomastractorsvc Posted February 24, 2016 Share Posted February 24, 2016 That is a great question all the Cummins service manuals I have do not discuss any specific pressure. Talks about low boost in trouble shooting and exhaust smoke and goes through the symptoms and steps from checking to see if it is the correct turbo to cleaning the air intake to checking exhaust restrictions. The manuals tell how to check and replace the turbo and where to check for leaks and pressure test the seals but nothing about a specific boost pressure.Call Cummins and ask the service counter. Quote Robert"I reject your reality and substitute my own." Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325527 Share on other sites More sharing options...
gearhead204 Posted February 24, 2016 Share Posted February 24, 2016 sounds a touch low for being "fueled up" I was thinking around 24 for normal, but it has been a while since I pulled any thing with a 350. Quote Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325532 Share on other sites More sharing options...
Dirtymilkman Posted February 24, 2016 Share Posted February 24, 2016 Just be careful with the fuel pressure screw. A little to much gogo and the cam loses lobes. Quote Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325533 Share on other sites More sharing options...
carlotpilot Posted February 24, 2016 Share Posted February 24, 2016 don you are right in the ball park with boost pres for a 350. there is no absolute pressure. some engs. will produce a little more or a little less Quote Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325534 Share on other sites More sharing options...
GreenGiant2 Posted February 24, 2016 Author Share Posted February 24, 2016 Cummins don't know squat anymore. All new guys. Got some old timer in the area I can ask. Quote We the unwilling, Lead by the unqualified, are doing the impossible, for the ungrateful. Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325543 Share on other sites More sharing options...
ws721 Posted February 24, 2016 Share Posted February 24, 2016 We have a B.C. 3 doing @ 15 lbs of boost. Then another B.C. 3 doing @ 30 lbs of boost. There is a formula for figuring H.P. I think its for every 1 lb to 1.5 lbs of boost a B.C. will make @ 20 to 22 H.P. Now that's a very crude estimate. If you want to make a B.C. respond well get your self a dual feed kit. Well worth the cost. A "Fast Fuel" will make a big improvement also. I do those things before getting into the pump. Also make sure your fuel supply lines are big enough and in good order. Seen that happen a few times where the lines were detereating and restricting fuel flow. Remember this, Air is free, give it all it wants. have a good fuel flow to the pump. Then tinker from there Quote Remember if it's got a hood it's no good! Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325559 Share on other sites More sharing options...
GreenGiant2 Posted February 24, 2016 Author Share Posted February 24, 2016 Flow to pump is good. Want to change turbo next and install Pyro to see difference. Have been thinking about doin a dual feed. They say dual feed can get ya about 25 extra ponies Quote We the unwilling, Lead by the unqualified, are doing the impossible, for the ungrateful. Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325568 Share on other sites More sharing options...
thomastractorsvc Posted February 24, 2016 Share Posted February 24, 2016 We have a B.C. 3 doing @ 15 lbs of boost. Then another B.C. 3 doing @ 30 lbs of boost. There is a formula for figuring H.P. I think its for every 1 lb to 1.5 lbs of boost a B.C. will make @ 20 to 22 H.P. Now that's a very crude estimate. If you want to make a B.C. respond well get your self a dual feed kit. Well worth the cost. A "Fast Fuel" will make a big improvement also. I do those things before getting into the pump. Also make sure your fuel supply lines are big enough and in good order. Seen that happen a few times where the lines were detereating and restricting fuel flow. Remember this, Air is free, give it all it wants. have a good fuel flow to the pump. Then tinker from there I have never heard of that calculation. The 400 Cummins <(Previous Owner and build sheet)> in the Superliner which I am not sure if it is a 350 or 400 <(depending on the valve cover writing you believe that was paint marked on the valve cover)> boost needle will jump up to 30 + lbs of boost, which means it is at least a 600hp engine. 1lb Boost =20hp x 30lbs boost I guess its a Hot Rod! Quote Robert"I reject your reality and substitute my own." Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325581 Share on other sites More sharing options...
theakerstwo Posted February 24, 2016 Share Posted February 24, 2016 I was waiting to see if any one could believe that formula.Sounds like it came over the radio.There is too many varaibles to consider.If this was true we would not need a dnyo. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325584 Share on other sites More sharing options...
ws721 Posted February 24, 2016 Share Posted February 24, 2016 LOL. Relax folks. Its just a ruff rule of thumb. OK follow this if you can. A 300 B.C. makes @ 15 lbs of boost. Our 600+ makes @ 30 to 31 lbs of boost. Its not cast in stone just a crude gage. If you have a B.C. making @24 lbs then id she is running good. And yes a dual feed set up will gain you @ 22 to 25 H.P. That's from the "experts" not me. It will also start a lot better and have much better throttle response. Now that ive stirred up a hornets nest im going to watch Trump Quote Remember if it's got a hood it's no good! Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325585 Share on other sites More sharing options...
thomastractorsvc Posted February 24, 2016 Share Posted February 24, 2016 If my boost was not so high I could see that. Maybe the by pass is not working. Quote Robert"I reject your reality and substitute my own." Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325589 Share on other sites More sharing options...
GreenGiant2 Posted February 24, 2016 Author Share Posted February 24, 2016 Looks like that says cpl is 797 Quote We the unwilling, Lead by the unqualified, are doing the impossible, for the ungrateful. Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325609 Share on other sites More sharing options...
GreenGiant2 Posted February 24, 2016 Author Share Posted February 24, 2016 Timing and head gasket thickness is the only difference between a 350 and 400. I think that's what I read Quote We the unwilling, Lead by the unqualified, are doing the impossible, for the ungrateful. Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325610 Share on other sites More sharing options...
theakerstwo Posted February 24, 2016 Share Posted February 24, 2016 Greengiant some one has been pulling your leg. 1 Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325619 Share on other sites More sharing options...
wingman Posted February 25, 2016 Share Posted February 25, 2016 Check with Pittsburgh Power. 2 Quote Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325630 Share on other sites More sharing options...
GreenGiant2 Posted February 25, 2016 Author Share Posted February 25, 2016 How do u mean? Quote We the unwilling, Lead by the unqualified, are doing the impossible, for the ungrateful. Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325632 Share on other sites More sharing options...
GreenGiant2 Posted February 25, 2016 Author Share Posted February 25, 2016 I have checked with PP and have been reading an old article about juicing up a cummins. Alot of good info. Have also talked to them about dual feed Quote We the unwilling, Lead by the unqualified, are doing the impossible, for the ungrateful. Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325634 Share on other sites More sharing options...
theakerstwo Posted February 25, 2016 Share Posted February 25, 2016 Talking about difference in a 350 and 400 is pistons, timing and injectors plus turbo and fuel pump calibration.What PP is talking about is pumping up your pump and and maybe a turbo change with maybe a timing change.That will work but once you get use to the power and get tire and sleepy you can burn the engine.You start set the fuel up on the higher compression piston you will have to watch the pyrometer very close.When PP gets thru with you there is no warranty and remember he is selling parts. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325655 Share on other sites More sharing options...
GreenGiant2 Posted February 25, 2016 Author Share Posted February 25, 2016 Right now my pump is set up for a 400 and turbo a pears to be the same in the books. I know that pistons are different and all that PP was doing was getting a dual feed. I have the new turbo that is for a 350 to 450 hp. The spare pump I have is to big right now and so are 190 injectors Quote We the unwilling, Lead by the unqualified, are doing the impossible, for the ungrateful. Link to comment https://www.bigmacktrucks.com/topic/44115-big-cam-turbo-boost-pressure/#findComment-325687 Share on other sites More sharing options...
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