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Discussion Starter #1
Been a LOOOONNNNGGGG time since I dealt with a stockish Powerstroke. :D

My wife's "new" truck (the '97) was doing 15psi tops when you hammered on it...wouldn't even show boost when cruising at 55mph.
It had a 3" hypermax DP with a 4" cat-back exhaust, K&N air filter, hypermax I/C (the lesser one), and supposedly a hypermax chip (haven't pulled the kick panel yet).

Yesterday I went to remove the cat, and found that the whole exhaust was on it's last leg. Went ahead and put a 4" straight exhaust (it was what I had sitting around) out the back.

Now her truck is boosting 3-5psi cruising at 55mph, and topping out at 25psi.

I can't remember the last time I drove an OBS Powerstroke before and after a cat removal and exhaust. (Probably been a decade) Is this a normal difference?


Thanks,
Phillip
 

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I can see 30psi without a chip, so 25 with a chip and 1.15 exhaust housing seems normal. Only possible explanation of that much change is due to the cat being clogged, not flowing enough.
 

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whistle tits
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I can see 30psi without a chip, so 25 with a chip and 1.15 exhaust housing seems normal. Only possible explanation of that much change is due to the cat being clogged, not flowing enough.
On what, your p pumped 24 valve? Lol, seriously, you mean your stage 1's with no tune?
 

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:whs: Im lucky to get 20 psi out of mine the way it sits. I have a d66 and 1.0 on the way for it though ;)
 

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Yes, stage ones no chip. The p24v sees just a little more boost that the Powerstroke does.
 

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STILL LEARNING
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STOCK truck worn no mods will see 17-19psi

a chipped truck, exhaust and air intake will see 25-30psi

Kentucky, I am going to say the cat was clogged
 

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I think you should try a different boost gauge.
It stays with the Map sensor till 20psi where the regulator it set. Plus it will only do that if I floor it on an on-ramp. Flat ground maxes out at 23-25psi. Remember I also have a 1.0 housing with SD compressor wheel.
 

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Discussion Starter #10
I looked in the cat and shined a light through the opposite side...I could see light as I moved it around and it really didn't look clogged at all.

If I had put this boost gauge on at the same time as the exhaust, I would wonder about the gauge...but it was showing lower than expected, and now the same gauge is showing higher than expected. Doesn't seem like a gauge would do that.

The muffler did have one baffle in it, but that baffle had a bunch of holes in it. Between those holes and all the holes forming down the pipe going to the muffler, I would think it would have been breathing fine.

Hmmm...

Thanks,
Phillip
 

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i can get to 25 psi with chip exhaust dp and intake
 

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Terminator Nation
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Well, I pull 408 hp with stageII 160s, e-fuel and 1.0 at 32psi with an old tune. 399.8hp at 31psi no e-fuel. and and about 20psi with a chip. 1.0, intercooler, no cat or injectors and a intake way back when. Thats why I wonder where the high boost numbers come from.
 

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Discussion Starter #13
Well, I pull 408 hp with stageII 160s, e-fuel and 1.0 at 32psi with an old tune. 399.8hp at 31psi no e-fuel. and and about 20psi with a chip. 1.0, intercooler, no cat or injectors and a intake way back when. Thats why I wonder where the high boost numbers come from.
Hmmm...are your up-pipes in decent shape? No boost leaks? If everything checks out and your turbo is in decent shape, maybe your gauge is wrong?

I don't remember what my truck was boosting before I put in the baby swamps (about a decade ago), but my '95 now has 350,000mi and has been topping out at 35psi ever since I got the injectors. That's with a 1.15 exhaust housing and on my second highest chip setting (I don't use the highest setting because it advances the timing too far.)
I recently pulled the turbo to find that the exhaust turbine was in bad shape...very eroded. The thrust washer/bearing had worn enough that the bearing just recently started getting into the backing plate. Even with the turbo being this far gone, it still did 35psi easily.

On edit: The tunes are a decade old too.

-Phillip
 

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Discussion Starter #14
Haha, I just went back through the archives of another forum from back in the good old days of building 7.3s. I put my new tunes in for my new baby swamps on 2/2/2005. Over 9 years ago. :)

Here are the tunes on my '95:
7/04 MLE1 High idle TS
7/04 MLE1 100 TS
7/05 MLE1 Fuel 7
DP MLE1 Hot
DP MLE1 XTR
Jodi MLE_1 BabySwamp

It's Jodi's program that was way too far advanced. The DP MLE1 XTR is my favorite. I went on to later start a post about injection timing that I believe helped get some people thinking. A bunch of the good 'uns were in there discussing. The guys from Swamps, Ryan Bean, Byron Eddins, etc. Not too long after, a drop in timing advance finally got the 7.3s over that 450-500hp rod blowing and piston cracking hump that existed for a while.

It was cool back then. It wasn't about mixing bolt-ons. Everyone was trying to figure out what would work and what wouldn't work when it came to getting power out of these engines.

Anyway...I'm gonna try and find a post saying what kind of boost numbers I was running before the babies.

-Phillip
 

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Terminator Nation
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Hmmm...are your up-pipes in decent shape? No boost leaks? If everything checks out and your turbo is in decent shape, maybe your gauge is wrong?

I don't remember what my truck was boosting before I put in the baby swamps (about a decade ago), but my '95 now has 350,000mi and has been topping out at 35psi ever since I got the injectors. That's with a 1.15 exhaust housing and on my second highest chip setting (I don't use the highest setting because it advances the timing too far.)
I recently pulled the turbo to find that the exhaust turbine was in bad shape...very eroded. The thrust washer/bearing had worn enough that the bearing just recently started getting into the backing plate. Even with the turbo being this far gone, it still did 35psi easily.

On edit: The tunes are a decade old too.

-Phillip
That was with two different sets of upipes, 1.0 turbos and gauges and making 408hp with 160 splits with an old 2003 tune on a DynoJet 248., At the time, I also had access to a calibration standard. So, between the cal standard, dyno readings and quarter times, I doubt my stuff was off.
 

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Discussion Starter #16
That was with two different sets of upipes, 1.0 turbos and gauges and making 408hp with 160 splits with an old 2003 tune on a DynoJet 248., At the time, I also had access to a calibration standard. So, between the cal standard, dyno readings and quarter times, I doubt my stuff was off.
That's pretty interesting. I don't know why your boost would be so low then.
 

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his boost number is lower because his setup was working and making power rember boost is a restriction of flow from my gas and racing world changing an intake may lose 3-5 pounds but would pick up 50-60 hp the fuel tuning on our engines have alot to do with that too

also Dave im impressed that u got it to spool good on a 248 dynojet them thing spin up so easy with low torque gas engines
 

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The particular DynoJet 248 I use has 5000# rollers instead of the usual 2000# or so and no load cell. Its one of just 3 DynoJets in the country that use the heavy rollers, the shop owner is a big diesel fan and has done several Diesel dyno meets. The big rollers make it a little more turbo diesel friendly. Although most of the Dodge boys complain about low boost numbers while on this dyno.
 

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never knew they had a 5k the one I have used is said to have a 3500lb roller and i wasnt impressed but im sure the 1500lb diff would help alot
 

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Discussion Starter #20
his boost number is lower because his setup was working and making power rember boost is a restriction of flow
You would be absolutely correct...if he actually had less restriction.
Writing this in the morning (while my brain is still fresh), It seems (from what little info I see about his setup) that he has a stock exhaust (or muffler) with no cat (CARB REGS?), probably a 3-3.5" DP, maybe a gutted EBPV, a 1.0 turbine housing, and an intercooler.

The I/C in his setup in an example of something that does lower boost pressure, but increases power because the charge air becomes cooler (more dense).
Another example would be a turbo with a better efficiency range than our TP38 turbos have.

Dave is putting more fuel to his engine and making a fair bit more power than what my '95 likely makes, but (if my assumptions about his setup are correct) he also has more restriction. If he has the stock tailpipe...they are very restrictive. If he has the stock muffler...same thing. 3-3.5" downpipes are much better than stock, but with the sharp bends, they could be better. Any amount of backpressure on the cold side of the exhaust will work to offset the backpressure on the hot side, thereby lowering boost.

On my '95, I am running baby swamps, an electric fuel system, a tymar intake, a custom fabricated 4" dp adapter (which completely replaces my ebpv), a 4" downpipe, and a 5" exhaust with a 5" flow-through (no baffles) style muffler.

My turbo has been boosting more psi for longer than anyone said it would, and I credit very low exhaust restriction to that. That would also be why I am boosting more, but making less power.

BTW, Dave...I am not picking your setup apart, just works out to be a good comparison for discussion. You ARE still making more power than I am! :D

-Phillip
 
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