1.6 NA Giles vs non-Giles fuel economy comparison

[rabbitman]

The differences are confusing, but could it be something simple like the wrong thickness HG on the Gilesified engine?

What temp t-stat does each one have? Does one have more belt-ran accessories than the other?

Also alignment, tire pressure, dragging brakes and thick bearing grease will make a difference and some tires have a higher rolling resistence too.

Right now I'm in the low 30s, that's partly due to the cold but strangely this is my lowest for the last 4 years while last summer was my highest at 46-48mpg .

I could handle getting your mileage.

[Wayland]

What temp t-stat does each one have?

Good point. My mileage went up 3mpg by replacing a thermostat that wasn't quite closing all the way.

[R.O.R-2.0]

whats each one timed at?

they shouldnt be timed the same, not with one having 135s and the other engine having 155s.. the one with the merc nozzles should get slightly more initial timing.

[overdrivegear]

whats each one timed at?

they shouldnt be timed the same, not with one having 135s and the other engine having 155s.. the one with the merc nozzles should get slightly more initial timing.

Giles pump is at 0.95mm, BOSCH pump is at 1.00mm.  Tire pressures are both at the sidewall max (44 psig).  Both have the same amount of belt accessories, both have new 87C thermostats, both have new wheel bearings, etc etc.  (I do agree that operating temp has a significant influence on fuel consumption, emissions, and carbon build up).  Although the alignment of the cabriolet is out a little bit...Like I said, this is not at all scientific but just for thumb in the air estimates, it seems a little odd.  Obviously there are plenty of out there that disagree.  If I ever got less than 40 MPG in one of these IDI NA engines, I'd do a full-on TDI swap.  Making only 70 lb.ft. of torque and getting 30s MPG is ludicrous.   

[coke]

I'm no expert by any means, but I do know Giles recommends 0.95mm/.037in advance, when using 130 bar injectors.  He told me if for whatever reason you are using 150/turbo injectors to use the advance spec specified for the turbo motor. 

I don't have my bentley in front of me (Im at work, saving lives ) but isn't turbo spec timing advance 1.05mm?

[R.O.R-2.0]

whats each one timed at?

they shouldnt be timed the same, not with one having 135s and the other engine having 155s.. the one with the merc nozzles should get slightly more initial timing.

Giles pump is at 0.95mm, BOSCH pump is at 1.00mm.  Tire pressures are both at the sidewall max (44 psig).  Both have the same amount of belt accessories, both have new 87C thermostats, both have new wheel bearings, etc etc.  (I do agree that operating temp has a significant influence on fuel consumption, emissions, and carbon build up).  Although the alignment of the cabriolet is out a little bit...Like I said, this is not at all scientific but just for thumb in the air estimates, it seems a little odd.  Obviously there are plenty of out there that disagree.  If I ever got less than 40 MPG in one of these IDI NA engines, I'd do a full-on TDI swap.  Making only 70 lb.ft. of torque and getting 30s MPG is ludicrous.   

the giles pump has 155 bar right?

and the bosch has 135 bar right?

your timing is backwards.. thats why one car gets better mileage.

should set your timing based on the break pressures of your injectors..

155bar open later then 135 bars..

[Mark(The Miser)UK]

whats each one timed at?

they shouldnt be timed the same, not with one having 135s and the other engine having 155s.. the one with the merc nozzles should get slightly more initial timing.

Giles pump is at 0.95mm, BOSCH pump is at 1.00mm.  Tire pressures are both at the sidewall max (44 psig).  Both have the same amount of belt accessories, both have new 87C thermostats, both have new wheel bearings, etc etc.  (I do agree that operating temp has a significant influence on fuel consumption, emissions, and carbon build up).  Although the alignment of the cabriolet is out a little bit...Like I said, this is not at all scientific but just for thumb in the air estimates, it seems a little odd.  Obviously there are plenty of out there that disagree.  If I ever got less than 40 MPG in one of these IDI NA engines, I'd do a full-on TDI swap.  Making only 70 lb.ft. of torque and getting 30s MPG is ludicrous.   

the giles pump has 155 bar right?

and the bosch has 135 bar right?

your timing is backwards.. thats why one car gets better mileage.

should set your timing based on the break pressures of your injectors..

155bar open later then 135 bars..

ROR
I think you've mixed the pressures up:

87 Cabriolet w/ diesel conversion:
Hydraulic lifter engine
Giles IP
Giles 135 BAR injectors
Stock 1.8 gasoline exhaust with Cat. delete
AGS transmission w/ 0.71 fifth, 3.94 diff (2500 RPM @ 60 mph)
Stock wheels/tires 175 tire width

85 Golf 1.6 NA (2-door)
Solid lifter engine
Stock BOSCH IP
155 BAR injectors w/ Merc nozzles
Stock 1.6 NA exhaust
ACH transmission w/ 0.71 fifth, 3.94 diff (2500 RPM @ 60 mph)
81 Rabbit steel wheels 155 tire width


Why should a 'Giles pump need to be advanced to 0.95 for 130 bar, but remain standard for turbo spec [155 bar]?

However, as it stands, swapping the whole lot and keeping the timing with the swap, will remove/compile all the variables and show the effect of the different bodies, assuming the engines are of similar condition... After doing this you will see which pump is tuned for economy better, or the results will give identical results [unlikely]

[R.O.R-2.0]

yup, mixed it up..

[lyeinyoureye]

I'm also not convinced that coasting out of gear saves fuel.  These un-throttled diesels don't have the same pumping losses of a gas engine with closed throttle.  You might decrease frictional losses in the trans, but during overrun, if the pump is adjusted properly, no fuel is injected.  If you are coasting in neutral, then you are burning fuel to idle the engine.  I doubt the frictional losses of the trans gears is more than the burned fuel to idle the engine.  

They were better than gas engines of the time, but they still have pumping losses. They're low displacement, so load tends to be high most of the time, especially given how people drive these days, but if someone is driving along at a moderate speed or on a large enough downhill slope it can be more efficient to operate the engine periodically at higher loads even w/ idle fuel consumption of ~.33gph in between. Like most things it depends on the specifics.

overdrivegear, I think you should try swapping the wheels/tires between the two before swapping over the whole drivetrains. Rolling resistance can vary widely between different tires and even between the same type of tire depending on wear.

[spdrace11]

Wow im having the same problem with my 91 Jetta coupe and 81 Caddy.  Both have 1.6 NA's and my Caddy gets 50mpg+ and the absolute best i have done in my Jetta with all hwy driving is 47.  I did notice however that my Caddy is geared differently then my Jetta and it obviously weighs less than the Jetta but that shouldnt seem to matter at a constant rate like on the freeway.  The Caddy definitely revs less on the hwy too and the gears seem to be farther apart than the Jetta's. 

Now im new to the actual gear ratio thing but im slowly learning.

I am in the process of trading a MKII vr6 for a low mileage MKII Jetta 1.6na with ~100k on the motor and a yr old Giles pump.  Now the Giles pump on the motor was built to "performance" specs according to the owner which concerns me due to possible lower mpg for the sake of power.  I dont care about power, thats what vr6's are for.  But when i Emailed Giles about the rebuilt pump he replied that the mpg will improve due to the motor working less to maintain the same speed.  So im in the same boat and will be watching this thread closely

[lyeinyoureye]

In your case it probably is a transmission difference causing a mileage difference since the 90s IDI diesels were a bit wound up IIRC.

[spdrace11]

In your case it probably is a transmission difference causing a mileage difference since the 90s IDI diesels were a bit wound up IIRC.

Anyone know of any good sites to research what gearbox ratio's came in what cars ect.

Sry for the highjack 

[rabbitman]

In your case it probably is a transmission difference causing a mileage difference since the 90s IDI diesels were a bit wound up IIRC.

Anyone know of any good sites to research what gearbox ratio's came in what cars ect.

Sry for the highjack 

From my memory, scirroco.org/gears also the faq has links to all this good info.

[spdrace11]

When i Emailed Giles about the rebuilt pump he replied that the mpg will improve due to the motor working less to maintain the same speed.

As always, hearsay can be thoroughly misconstrued, but that doesn't make any sense to me.  Steady state cruising requires a specific amount of power.  The engine will work exactly that "hard" to maintain that speed regardless of what pump and injectors are fitted.  If instead he said that he has significantly improved overall engine efficiency then it might make sense.

Sorry this is the email i received.

"Hi
no it will make it better, since you have more Torque and HP then you can drive the car easier and still get the same speed.
Giles
 

From: [email protected]
Sent: Friday, February 04, 2011 4:30 PM
To: [email protected]
Subject: VW Diesel pump"

[lyeinyoureye]

Maybe he's referring to the retarded timing given factory advance and ULSD?