Improve mileage 350 with Quadrajet

[kikkegek]

Originally Posted by motornut

I'm guessin you have a small pipe from the intake to to waterpump or threw the heater core
(need pics)
the pipe will bypass the stat = heat sooner inside

do you have a schematic of how the water flow through the engine, radiator and heater core? that would help me a lot.

[motornut]

post a pic of the engine standing by the wheels
get the rad hoses and block in the pic both sides

[kikkegek]

I already got some more info.

I took the upper radhose of tonight and with cold engine there is no flow. This is good, this means the thermostaat DOES close at low temp.

I think the thermostaat opens at the right temperature and dont think this is causing the problem....I now really suspect the Flexfan cooling the engine all the time is the main problem of my engine not getting above 150F....

I am installing a 2400cfm electric fan this weekend and hope this solves my problem of a cold engine....I'll keep in touch....

[kikkegek]

btw heres the pics

passengerside:


driverside:


its probably hard for you to draw in these pics, because the engine is blokked by hoses for the evaporator of the LPG system that is in my car...(silver round device on driverside) It is parallel connected to the heatercore.

[kikkegek]

after replacing my brakes front and rear completely (calipers, shoes, cilinders and pads) and replacing the vacuum advance. we did some highway driving this weekend. Picked up a princesbed for our doughter about 70miles from here.


We drove for bout 2 x 70 miles about 55-60mph.
the engine temp didnt go above 150F again...far too cold I say.

we got gas when we got back and the mileage was 1:3,8 in km/l...thats 8,9 mpg
here in town and short highway trips we only get about 7,5 mpg...still not very good...

the tach showed about 3000rpm all the time...thats probably a big influence in our mileage.

I als started to mount a electric fan to replace the Flexfan, hoping this will improve the mileage a little, make the engine bay look better and get the engine temp up...and what do you know...I drove around this morning with the flexfan on, but without the shroud and the engine temp got up to 170F after just a 10 mile roundtrip...tghats 20 more then the 150 we have been getting...I bet when the electric fan is on and the flexfan is of the temp will go up to 190-200 were it should be with a 195F thermostat...

i'll be back!

[kikkegek]

got the electric fan setup done and it looks pretty fine.





and finally, my engine gets up to operating temperature. It hadnt gotten above 150F for over a year now! main reason...damn Flexfan! took it off, replaced it with an electric fan and voila..engine heats up nice and quick and when the fan hits 200F, it cools down within 1 or 2 minutes to 185F.



only thing left is to attach a LED parellel to the electric fan, so I can see on my dash if the fan is running or not...thanks for the tip Gchemist

[motornut]

looks good but i'm not sure if it will cool enough
the shroud funnels the air threw the whole rad
that setup may not get enough air threw,some being blocked, some being open with no draw

[motornut]

Originally Posted by kikkegek

after replacing my brakes front and rear completely (calipers, shoes, cilinders and pads) and replacing the vacuum advance. we did some highway driving this weekend. Picked up a princesbed for our doughter about 70miles from here.


We drove for bout 2 x 70 miles about 55-60mph.
the engine temp didnt go above 150F again...far too cold I say.

we got gas when we got back and the mileage was 1:3,8 in km/l...thats 8,9 mpg
here in town and short highway trips we only get about 7,5 mpg...still not very good...

the tach showed about 3000rpm all the time...thats probably a big influence in our mileage.

I als started to mount a electric fan to replace the Flexfan, hoping this will improve the mileage a little, make the engine bay look better and get the engine temp up...and what do you know...I drove around this morning with the flexfan on, but without the shroud and the engine temp got up to 170F after just a 10 mile roundtrip...tghats 20 more then the 150 we have been getting...I bet when the electric fan is on and the flexfan is of the temp will go up to 190-200 were it should be with a 195F thermostat...

i'll be back!

it looks kinda like the one the royal wedding will use too

[kikkegek]

Originally Posted by motornut

looks good but i'm not sure if it will cool enough
the shroud funnels the air threw the whole rad
that setup may not get enough air threw,some being blocked, some being open with no draw

untill now everything goes just fine. my engine only seems to hit 200F now (finally) after driving some highway and then letting it sit and idle for atleast 4-5 miuntes. If I keep driving though town, it wont overheat.

and when it sits and idles and hit the 200F it is cooled down to 185F in 1-2 minutes..summertime will be the big test...fingers crossed! but it looks good! I can finally see my engine! hahaha

[erikgto]

The big question is; will you mpg's improve now the engine's getting up to it's proper operating temperature.....

Keep us posted.

[kikkegek]

I dont have any hope for that...although it will be better for engine life expentancy!

untill now nothing seems to improve my mileage:
- new spark wires (old ones spark against engine)
- LPG tune up
- changed timing from 0 BTDC to 10 BTDC
- Cold Air intake
- flex fan in stead of fixed fan
- and now electric fan
- changed the vacuum advance for a new one
- flushed the cooling system
- replaced brake calipers and pads front and cilinders and shoes rear (they were rubbing)

every time I think, THIS will make a difference....NOT!

recently we drove 55 mph for 200 km and our mileage improved from an average of 6 to 7.....big deal! hahahaha....

[Adams74Chevy]

There should be at least a slight improvement since your engine does not have to turn the fan constantly anymore. I don't know if it would enough to notice or not.

[kikkegek]

Originally Posted by Adams74Chevy

There should be at least a slight improvement since your engine does not have to turn the fan constantly anymore. I don't know if it would enough to notice or not.

it does idle a little higher and the engine seems more responsive to the throttle. revving easier!

MPG will follow soon! i'll be back!

[kikkegek]

Mpg seemed to have improved from 6 to 7 Mpg.
Posted via Mobile Device

[kikkegek]

hahaha suc6....

I got gas this night for the second time after changing to the electric fan and indeed, theres improvement.

My MPG was 7,5 mpg

and after the first tank of gas I got 8,23 mpg
and 2nite I got gas again and it was up even more to 8,7 mpg

finally some improvement.

I wonder if it is the warmer engine or the removed flexfan that is causing this improvement...

I am happy!
:-)

[kikkegek]

I drove some highway miles this weekend. Did about 55-60 mph...

My milage was 9,24...

I guess its tw thing causing better milage....warmer engine and less drag of the flexfan...wonder wich makes the most?

[kikkegek]

because I was scared I was cooling my engine through the heater core return connection on my radiator, I moved this connection from the radiator to the waterpump.

Normally the heatercore does not get any water untill you demand heating in the cabin. But in my setup the evaporator for my LPG system is connected in parallel to it. Therefor I was thinking I was circulating water through the passenger side of the radiator and therefor cooling the engine. Because on the highway my engine does net get any hotter then 160F....

Well....moving the connection to the waterpump, didnt change a thing. in front of a traffic light the engine will warm up to 200F easily...but as soon as I start driving the temperaature will go down to about 160F...highway and city...

I have absulutely no clue what could be cooling my engine...please help!

[motornut]

when i did my heater core in my 88 I remember a valve to stop the flow to the rear tho there was no valve to stop the coolant going threw the core
unless my hook up was wrong

Would it be worth it to try with no heater core connected?
or put a valve or two in to shut it off?

[kikkegek]

Originally Posted by motornut

when i did my heater core in my 88 I remember a valve to stop the flow to the rear tho there was no valve to stop the coolant going threw the core
unless my hook up was wrong

Would it be worth it to try with no heater core connected?
or put a valve or two in to shut it off?

I am not using any heat in the car, so no heat is lost there...and this should be so little compared to the heat produced by a 5.7 litre V8 engine...which has an efficiency of maybe 30%, burning a lot of fuel every km...

I am cooking the thermostat 2nite, to see when it opens. I'll upload a video soon...

[kikkegek]

alrighty, tested the thermostat 2nite. I dont have a thermometer, so I used the thermo-cap from my rad to measure the temperature.

at 80C (175F) it starts to open. You can see this in the video at about 55 seconds when the bubble escapes from under the thermostat.

at about 2 minutes the thermostat is wide open when the water cooks.

when it cools down it is closed again at 80C (so 175F). that is at about 6 minutes into the video.

isnt opening up at about 175F to early for a 195F thermostat?

this is the youtube video:

YouTube - Thermostat test 195F

[kikkegek]

ever since I cooked and tested the thermostat, the engine seems to warm up a little further and remain warmer on road and highway trips. And this makes me very happy.



I also noticed that my mileage improved even further.

the last two times I got gas (LPG in my case) I had a mileage of 9.4 MPG and 8.7 MPG

Something else I noticed is that the scale on the temperature gauge on the dash is not lineair:

the left side runs from 100 to 210. A difference of 110 degrees.
the right side runs from 210 to 260. A difference of only 50 degrees.

So who know what the number is for the points in between on the left and right side of the 210F?

[kikkegek]

ever since I cooked and tested the thermostat, the engine seems to warm up a little further and remain warmer on road and highway trips. And this makes me very happy.



I also noticed that my mileage improved even further.

the last two times I got gas (LPG in my case) I had a mileage of 9.4 MPG and 8.7 MPG

Something else I noticed is that the scale on the temperature gauge on the dash is not lineair:

the left side runs from 100 to 210. A difference of 110 degrees.
the right side runs from 210 to 260. A difference of only 50 degrees.

So who know what the number is for the points in between on the left and right side of the 210F?

[kikkegek]

changed my sparkplugs after 12.000 miles and put a clean airfilter in after 6500 miles.

mileage is now at 9.5 mpg

[lilpoindexter]

What kind of transmission is in your suburban?

[kikkegek]

Originally Posted by lilpoindexter

What kind of transmission is in your suburban?

TH400 with a killing end gear ratio of 1:4.1

My engine makes 3000 rpm when driving 90-100 km/h (about 55-60 mph)