18 non waste gate turbo housing
03-28-2005, 12:12 PM
#6
Registered User
Thread Starter
Well if you just follow the history and economy of these engines it would be the logical mod. When they first came out they had a 21 and the cam was a full commercial engine cam and pump. The engine was capable of getting over 25 miles per gallon. The engine was designed to pull freight. The lag time was great for supermarket running so they went to an 18, and later to smaller housings. Finally ending up with a 12 wg and getting stock about 17 mpg.
The 24 valve engine added more breathing and electronic pump control and of course the EPA cam and good response for spermarket use. It got 17 or 18 stock. My use is the fully commercial use as was originally intended, it has the full commercial cam (non EPA), runs 28 to 30 pounds of pressure at half throttle pulling a hill.
Truck sources will tell you that on a pulling engine the boost should settle out at 15 or 16 pulling and this is done with less exhaust restriction which generates more economy. I could care less for the light to light response. My only concern would be excessive smoke on leaving a light with a load.
Higher boost levels are generated to help cool the EGT's and on mine it rarely sees over 1000 degrees, so this is not a concern. The first mod recommended for power and economy pulling hills with a diesel engine under heavy freight is a larger housing. I have watched what the boost numbers are for the different combinations and it looks like the engineers were right in using the larger housings on B engines for pulling freight. EPA forced the smaller housings on the commercial engines, no practical reasons. My housing is much too small, part throttle will push it into waste gate right away. This is detremental to economy and pulling power.
So I will try the larger housing. Even if the lag time is excessive it will not be near the lag of a '91 or '92 engine that was stock and got high mpg.
The 12 valve engine and the 24 valve engine are just about the same with a couple of more valves and breathing better in the 24. Then the electronic added. 99% of the posts here are for hot rod type of power and rarely is there a post for pulling power. The price of fuel today is good reason for me to look to better flow to capture some of the mpg that could be gotten with a larger housing.
If I can get just one mpg more with the larger housing it is well worth the lag inconvenience and any loss of power involved it it does. I have the fastest pulling truck that I have found on the road with a hotshot sized engine, and could sacrifice a little for economy. I am sure that someone has one faster and better pulling but mine is essentally stock and is right up there with the best due to the ISB275 engine. One mile per gallon would net me a few dollars per day in savings. The profit made is the difference between costs and gross. One mpg is roughly $23 saved for three days of running at todays fuel prices. Now if it was 2 mpg... Who said there is no free lunch...
And I know, I will get all the reasons why I am wrong, such is life.
The 24 valve engine added more breathing and electronic pump control and of course the EPA cam and good response for spermarket use. It got 17 or 18 stock. My use is the fully commercial use as was originally intended, it has the full commercial cam (non EPA), runs 28 to 30 pounds of pressure at half throttle pulling a hill.
Truck sources will tell you that on a pulling engine the boost should settle out at 15 or 16 pulling and this is done with less exhaust restriction which generates more economy. I could care less for the light to light response. My only concern would be excessive smoke on leaving a light with a load.
Higher boost levels are generated to help cool the EGT's and on mine it rarely sees over 1000 degrees, so this is not a concern. The first mod recommended for power and economy pulling hills with a diesel engine under heavy freight is a larger housing. I have watched what the boost numbers are for the different combinations and it looks like the engineers were right in using the larger housings on B engines for pulling freight. EPA forced the smaller housings on the commercial engines, no practical reasons. My housing is much too small, part throttle will push it into waste gate right away. This is detremental to economy and pulling power.
So I will try the larger housing. Even if the lag time is excessive it will not be near the lag of a '91 or '92 engine that was stock and got high mpg.
The 12 valve engine and the 24 valve engine are just about the same with a couple of more valves and breathing better in the 24. Then the electronic added. 99% of the posts here are for hot rod type of power and rarely is there a post for pulling power. The price of fuel today is good reason for me to look to better flow to capture some of the mpg that could be gotten with a larger housing.
If I can get just one mpg more with the larger housing it is well worth the lag inconvenience and any loss of power involved it it does. I have the fastest pulling truck that I have found on the road with a hotshot sized engine, and could sacrifice a little for economy. I am sure that someone has one faster and better pulling but mine is essentally stock and is right up there with the best due to the ISB275 engine. One mile per gallon would net me a few dollars per day in savings. The profit made is the difference between costs and gross. One mpg is roughly $23 saved for three days of running at todays fuel prices. Now if it was 2 mpg... Who said there is no free lunch...
And I know, I will get all the reasons why I am wrong, such is life.
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03-28-2005, 06:19 PM
#9
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I may be wrong but with a mostly stock truck with an 18 housing would be a dog especially from a stop therefore with the bigger housing it will use more fuel to get going and stay going and your boost will be lower and egts a little higher at cruise. You might also try a 16.
03-28-2005, 06:48 PM
#10
Registered User
''a mostly stock truck with an 18 housing would be a dog'''
Maybe a mostly stock 160 hp engine, but I think that ISB275 means horsepower. I'm prolly nowhere near 275 rwhp and I can spool my 18.5 housing purty quick with the fuel I have. I'd like to think I have 200 hp at the wheels and I'm seeing about 6psi at 70mph empty. I figure with a good load it'd be right in that sweet spot HID is talking about with some room to breathe. Just my .02
greg
Maybe a mostly stock 160 hp engine, but I think that ISB275 means horsepower. I'm prolly nowhere near 275 rwhp and I can spool my 18.5 housing purty quick with the fuel I have. I'd like to think I have 200 hp at the wheels and I'm seeing about 6psi at 70mph empty. I figure with a good load it'd be right in that sweet spot HID is talking about with some room to breathe. Just my .02
greg
03-29-2005, 11:29 AM
#14
Registered User
Thread Starter
See once again you are forgetting the use. I never get to full throttle until fifth or six gear. Using full power at lower speeds and gears is just beating up on the truck and looking for broken driveline parts. Same goes for a big truck. So in normal use I don't see much boost going through the gears until at highway speeds.
03-29-2005, 11:41 AM
#15
Registered User
HID, would you need a new downpipe to mate to the 18.5? I'm sure you thought of that already, but I was thinking you have one of those cast elbows, right? You got an e-brake?
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