Is this Safe or can it be? Experts Needed!

[dds92780]

Okay i have made numerous posts about my truck and the power i'm making with it but i really want to hear from the experts here. I will give a brief history of the truck and why i am where im at today with it.

For starters its a 95 mack rd E7 350 mechanical with 442 rears and eaton 9 speed

First thing i did was get the pump turned up about 15-20 percent. I was happy with it.

Then i got Antrim oversized 20 percent injectors and i was very happy with how quick it responded and i could walk 427's and keep up with upper 450 hp trucks that cost 10x that mine did

The turbo i was using was a Schwitzer S300 and i would get 35 lbs of boost by only 1250-1300 rpm running 1 percent biodiosel

My pyro never got over 850 degrees with that setup.

I would now drive my truck in the rpm range of 1100 to 1500 with partial throttle and it moved good without creating smoke

The max boost i saw was 38 and thats on a really cold day.

I would be able to climb long hills in overdrive for a full minute and my pyro never even got to 900 and my boost would be at 37, my coolant temp stayed around normal too

So why did i want to change any of this? Truck ran like a dream.

Well, i wanted to get a slightly larger turbo ( i felt my s300 was getting maxed out) so that i would get a little more power out of it and in doing so i was hoping to increase mpg.

I know it seems backwards but it only makes sense to me that with a bigger turbo and if i'm able to drive on partial throttle then that means i would be getting a better match to the air with all the fuel i was already using up.

The turbo i went with is the mack turbo S400 found in a 427-460 mack rd legend. It's got a 1.25 exhaust compressor size vs my old 1.1

5 inch from turbo to dp then reduced to a 4 inch to muffler

I drove it for a day or two with the new turbo and i felt it wasn't any faster and maybe a tad slower than before so i headed to the pump shop where my guy turned it up more but i still didn't see much improvement in response

Well, he turned it up all the way for me now. I don't want no streetrod truck because this is also a work truck. I'm just trying to get more useable power out of this turbo without waiting for a spool then power up top vs low

What i noticed with it turned up all the way is that the boost comes on a little sooner but its strange because after 1600 rpm (which i never really take it to) starts to build more boost and get louder

I told him i wanted to get the power sooner otherwise ill go back down on the pump and put the smaller turbo back on. He said that would be going backwards and that my pump is maxed out

He said the pump i need is the mack 400 hp pump because it is setup for more power (my pump guy has a way of flow testing these pumps too)

The pump number of my current pump is 0 402 746 642 and its already been rebuilt two years ago. The timing is set to 11.5 degrees

The pump number he is recommending is 0 402 746 852 and it comes in the mechanical 400 hp mack and has timing of 19 degrees ( is this overkill)? he was telling me the old 300s ran 22 degrees of timing

I can see the value in getting that pump because he will put it in his machine and see where the fuel is coming in at vs my current one just being the rack all the way forward.

Are my pistons okay for doing all this?? My piston numbers are 240GC2250AM

I just want to make sure this isn't a bad idea. I have all the gauges i need and i look at them constantly. Truck has 450k on it right now

He told me that he has put bigger injectors, a 427 turbo and the 400 hp injection pump on a few macks and the guys have loved it. Are any of you guys on this site???

Only thing i can do is drive it for a week or so to really tell if i can get better mpg with half throttle on this bigger turbo than before and how it heats up.

I have not pulled a load yet so we'll see i guess

I just don't want to be a horror story of a blow headgasket or engine for that matter because i look at my gauges alot and i never floor it unless im in high side of gears.

Is it best to just get a bigger S300 made by borg warner or is this the turbo i should be using???

Let me know what you all think and thanks for looking. (maybe this thread will help others too)

[mrsmackpaul]

now first let me say one thing Im not judging at all or criticizing what you have done just curious as I feel in Australia all this hot rodding to the motors the engine life would be shortened to hours on heavy work but thats just me

so one thing to bear in mind with any of my comments is I have no experiance with hot rodding Mack motors car motors well I was young once

now to your question to me if I was to stand i front of a small fan and blow on it to get it to spin it would take a small puff of air if it was a big fan it would need a bigger puff of air

so if you were to start with a small turbo the motor would need to spin at a certain speed to fully spin the turbo so it would only stand to reason that on a bigger turbo it would need even more air to shift at the same speed so the motor would have to even rev harder move the turbo at the same speed and then if you were to add bigger load on the inlet side of the turbo ie a bigger fan then it would need even more revs from the ,motor to spin the turbo as fast as when you only had a small turbo on it

so from my ramblings I feel that what has happened is what I would expect to happen and the pump bloke is fairly accurate with what he says as the only way now or more to the point the next step is more fuel to give even a bigger bang at lower rpm's to help spin the turbo quicker or at least thats the way I see it

hope some of this makes sense

seeya

Paul

[dds92780]

yes you are correct on all that, I guess that to spin a bigger turbo at a lower rpm you would need more fuel sooner and only a bigger pump will do that?

What is the difference in my current pump being 11.5 degrees timing vs the 400hp one being 19 degrees timing???

What does that all mean? Will that be unsafe?

[dds92780]

I guess there aren't many people on here that have added power to their mack that care to chime in. Anyone else have an opinion? I have decided to just keep my current pump and maybe turn the pump back down. After all, i only drive with .25 -.5 throttle anyways and still get at least 5.5 mpg so i'm happy with that. I wish i knew how to turn it down though. I looked in the pump the other day. I took off the front cover with the two screws and i could see there is a screw on top in the pump with a locking nut, there is no thread left. I popped the middle cover off and its pushed all the way forward. Soo, if i want to turn my pump back down and dial it in the way i want to and experiment, is it as simple as just taking that locking nut off and turning the screw counterclockwise then putting the locking nut back on??? Or is there more involved than that?

[1MACK1]

Don't know what weights your pulling but that's doing ok

Remember they are 350 hp

I know that they go well I pull 420000 kg gross every day and up some huge climbs and it still surprises me what these motors will do

I drive at my mid 90s it will run at 100 + but at 95-97 I get a fuel burn of 2.46 km per litre day in day out with reliability

Just my 10 cents worth

[Timmyb]

I think when you start buying fuel pumps things could get expensive!

By the sounds of it you got great results from injectors and increase in fuel. And wouldn't have cost ya much. Good bang for buck.

Not so for the turbo, and I'm guessing you will be left dissapointed if you try a new fuel pump.

My opinion, just enjoy your truck as it is, and spend that $$$ you were gonna spend on the fuel pump on your missus or on a holiday.

[1MACK1]

Very good advise timmyb

[mrsmackpaul]

Don't know what weights your pulling but that's doing ok

Remember they are 350 hp

I know that they go well I pull 420000 kg gross every day and up some huge climbs and it still surprises me what these motors will do

I drive at my mid 90s it will run at 100 + but at 95-97 I get a fuel burn of 2.46 km per litre day in day out with reliability

Just my 10 cents worth

just quickly jumped on google and converted that equal's around 5.8 MPG and thats about what I would expect I dont know what you blokes do different than we do out here but our MPG is better than the over in the states I feel the speed you blokes drive at has a lot to do with speed limit in Australia is 100km/h or 60 Miles/Hour

Paul

[Timmyb]

Paul, I know the U.S. gallon is about 3.8l, where the imperial gallon is 4.5l. Depends which one you used?

[mack mhe9]

Yep we are limited to 80.000 lbs for the most part.

and they say for every 1 mph over 55 you lose a tenth of a gallon.

oh and we don't drive on dirt roads pulling 3 trailers.

As for the original post I would get a hold of Antrim Diesel again. They do this for a living. They know what parts to match with each other. Good luck