Boost in power.
Postmaster
Joined: Aug 2010
Posts: 2,554
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From: Northern Arizona
There are not many power " tricks" for a naturally aspirated IDI. About the best you can do is fresh injectors, fresh injection pump, correct timing, and free flowing intake and exhaust. That's about it. Sounds simplistic, but don't underestimate the change it can make. Most IDI's out there are crippled by neglect. It is understandable because a rebuilt fuel system costs the better part of a grand. Few people want to spend that kind of money on a 20-30 year old truck for just a "tune up". But honestly that's where you have to start with getting good results from an NA engine.
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New User
Joined: Feb 2015
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it has no cats and straight pipes it has new injectors and a new lift pump and I'm now putting new brakes on it including new calipers. She has a lot of power I was just wondering if there was anything I could do to help increase efficiency. The previous owner has neglected her but the only real problem she has is an oil leak around the heads and A leaky power steering pump.
Postmaster
Joined: Aug 2010
Posts: 2,554
Likes: 7
From: Northern Arizona
When you say efficiency, what are you currently getting as far as mpg? Your biggest mileage killers are going to be the dual wheels and most likely 4.10 axle gears with a non-overdrive transmission. Ouch.
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Joined: Feb 2015
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From: Avilla
Ford F834 is right about axle ratio & direct drive trans, don't know that duals cost much fuel, had a slew of duallies and srw only efficiency difference i noticed was rubber used, back in the day some guys were putting a 2 speed transfer in to get an overdrive, what size tire are you running, i figure your getting around 11 or 12 mpg, they didn't do a lot better than the 390cid gas did back in the 70's, beat the **** out of the 460 on mpg and the 351M on power, the selling point on that era was the longevity of the engine, you could step up to a 3.55 ratio & have plenty of power off the line with the granny in the 4 speed, or run a taller tire
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Joined: Jun 2014
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Yeah, lack of OD is kinda a killer in the relatively large displacement IDI's. 4.10's don't help either. Most of the 4 speeds are close ratio in these trucks meaning no granny gear. GM used crazy low in most of their (sm465) 4 speeds, Ford only in some. Kind of a bummer IMO, but FWIW if you find a t18 with granny it bolts *right* in if in the same configuration- 2wd and 4wd are not interchangeable.
Almost all ford 5 speeds behind diesels don't have the "granny" either, but in the 5 speeds they generally are referred to as "wide ratio" or "close ratio". Wide ratio means low first and reverse. Close ratio means tall first, but the gears are closer together. Most (all?) Big block gas 5 speeds got wide ratio, but require some work on the bolt pattern to fit to diesel engines.
3.55 and OD = better efficiency. Turbo = more power, but costly and even modest boost pushes limits of these high compression engines. Often adding a turbo will get worse fuel efficiency in real world driving with an IDI. There are a lot of reasons, but the two biggest reasons is that the IDI burn is already really clean (no waste fuel to burn), and people tend to run the engine harder netting a loss of fuel efficiency.
Almost all ford 5 speeds behind diesels don't have the "granny" either, but in the 5 speeds they generally are referred to as "wide ratio" or "close ratio". Wide ratio means low first and reverse. Close ratio means tall first, but the gears are closer together. Most (all?) Big block gas 5 speeds got wide ratio, but require some work on the bolt pattern to fit to diesel engines.
3.55 and OD = better efficiency. Turbo = more power, but costly and even modest boost pushes limits of these high compression engines. Often adding a turbo will get worse fuel efficiency in real world driving with an IDI. There are a lot of reasons, but the two biggest reasons is that the IDI burn is already really clean (no waste fuel to burn), and people tend to run the engine harder netting a loss of fuel efficiency.
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Freshman User
Joined: Feb 2015
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From: Avilla
Yeah, lack of OD is kinda a killer in the relatively large displacement IDI's. 4.10's don't help either. Most of the 4 speeds are close ratio in these trucks meaning no granny gear. GM used crazy low in most of their (sm465) 4 speeds, Ford only in some. Kind of a bummer IMO, but FWIW if you find a t18 with granny it bolts *right* in if in the same configuration- 2wd and 4wd are not interchangeable.
Almost all ford 5 speeds behind diesels don't have the "granny" either, but in the 5 speeds they generally are referred to as "wide ratio" or "close ratio". Wide ratio means low first and reverse. Close ratio means tall first, but the gears are closer together. Most (all?) Big block gas 5 speeds got wide ratio, but require some work on the bolt pattern to fit to diesel engines.
3.55 and OD = better efficiency. Turbo = more power, but costly and even modest boost pushes limits of these high compression engines. Often adding a turbo will get worse fuel efficiency in real world driving with an IDI. There are a lot of reasons, but the two biggest reasons is that the IDI burn is already really clean (no waste fuel to burn), and people tend to run the engine harder netting a loss of fuel efficiency.
Almost all ford 5 speeds behind diesels don't have the "granny" either, but in the 5 speeds they generally are referred to as "wide ratio" or "close ratio". Wide ratio means low first and reverse. Close ratio means tall first, but the gears are closer together. Most (all?) Big block gas 5 speeds got wide ratio, but require some work on the bolt pattern to fit to diesel engines.
3.55 and OD = better efficiency. Turbo = more power, but costly and even modest boost pushes limits of these high compression engines. Often adding a turbo will get worse fuel efficiency in real world driving with an IDI. There are a lot of reasons, but the two biggest reasons is that the IDI burn is already really clean (no waste fuel to burn), and people tend to run the engine harder netting a loss of fuel efficiency.
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Senior User
Joined: Jun 2014
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4:1 first aint' a "granny", sorry. 
As to gassers, I'm talking five speed gassers, which get a 5.79:1 first instead of the diesel which gets a 4:1 first. HUGE difference.
The sm465 got a 6.5:1 first and 6.09:1 reverse.
There were T18's that got wide ratio appropriately geared to call a granny, as well as T19's but as I read it they never came in pickups behind a diesel. But the fact that they are out there means they *could* go into a diesel. The 5.79 isn't as deep as the 6.32 in the four speed borg transmissions, but OD is a HUGE plus and these days ZF's are getting easier to find. Probably easier than finding (and identifying) a granny borg.
The Borg-Warner T18 & T19 Transmissions - Novak Conversions
http://en.wikipedia.org/wiki/Muncie_SM465_transmission
http://www.zf.com/na/content/media/u...NAL_2-1-09.pdf
BTW for what it's worth, swapping in a SM465 ain't rocket science. My buddy had one behind his souped up 390 with a gently modified bell housing.
PS something to remember when measuring gears by seat of the pants is that the diesels idle at about 500rpm and make GRUNT torque off idle where gassers idle more like 800-1000rpm and make half a squat of torque off idle. This makes a diesel feel a lot lower geared.
As to gassers, I'm talking five speed gassers, which get a 5.79:1 first instead of the diesel which gets a 4:1 first. HUGE difference.
The sm465 got a 6.5:1 first and 6.09:1 reverse.
There were T18's that got wide ratio appropriately geared to call a granny, as well as T19's but as I read it they never came in pickups behind a diesel. But the fact that they are out there means they *could* go into a diesel. The 5.79 isn't as deep as the 6.32 in the four speed borg transmissions, but OD is a HUGE plus and these days ZF's are getting easier to find. Probably easier than finding (and identifying) a granny borg.
The Borg-Warner T18 & T19 Transmissions - Novak Conversions
http://en.wikipedia.org/wiki/Muncie_SM465_transmission
http://www.zf.com/na/content/media/u...NAL_2-1-09.pdf
BTW for what it's worth, swapping in a SM465 ain't rocket science. My buddy had one behind his souped up 390 with a gently modified bell housing.
PS something to remember when measuring gears by seat of the pants is that the diesels idle at about 500rpm and make GRUNT torque off idle where gassers idle more like 800-1000rpm and make half a squat of torque off idle. This makes a diesel feel a lot lower geared.
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johnny diesel
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