96 5.7L Vortec - production block - Water pump coolant flow and heater core flow direction help

[L31MaxExpress]

It's a knock sensor, not a temperature sensor. Vibration--the result of detonation pressure-spikes ringing the combustion chamber(s) like a bell (heard all the way in the passenger compartment as "Ping" or "Knock")--travels very nicely through iron.

And...GM being GM...the hole was already there, unused and plugged.


Infrared thermometers are notoriously inaccurate. Aside from largely being cheap Chinese, there's also the emissivity of paint to contend with.

I looked all over the Internet for a photo of that. I guess I wasn't using the right keywords. I read about this years if not decades ago, in the Chevy Power book, 8th Edition.
www.amazon.com/Chevrolet-Power-Prepare-Engines-Performance/dp/1557880875/ref=sr_1_1?

Water pump pressure side drilled for outlets, leading to the "siamesed" exhaust ports, adding coolant that doesn't have to squeeze through holes in the block/head gasket/cylinder head. I've also seen photos of the hoses leading from the block drains, where the cool coolant from the block is re-routed to the hot cylinder head, bypassing the head gasket.

But again...there's mods to the block deck and gasket that can also improve coolant flow there.

Many of the newer blocks already had the cooling system ports revised and only need the head gasket updated.

 

[dtrader]

Great Pic L31maxExpress! Looks like a circle track motor to me?!

Thank you for the time/help in your post/s.

This is the type water circulation rework I'm looking for. "Visualizing" a project with unknowns vs "Seeing" with knows is a great help!

For me, in engine builds/swaps, external rework is less invasive, easily transferable and best suited for engines with different internal build parameters, not to mention for this project a pipe plug removes mod.

Thanks again df2x4 and L31maxExpress,

James

 

[L31MaxExpress]

Great Pic L31maxExpress! Looks like a circle track motor to me?!

Thank you for the time/help in your post/s.

This is the type water circulation rework I'm looking for. "Visualizing" a project with unknowns vs "Seeing" with knows is a great help!

For me, in engine builds/swaps, external rework is less invasive, easily transferable and best suited for engines with different internal build parameters, not to mention for this project a pipe plug removes mod.

Thanks again df2x4 and L31maxExpress,

James

Yep, found the image and picked it at random because it was setup that way through a google search of circle track engine. A CNC Motorsports roundy round job for sure.

I think that is an off the shelf Edelbrock pump that already comes with the ports tapped for the hoses.

 

[L31MaxExpress]

Found the Edelbrock pump I was thinking of. Already has NPT threaded holes matching 8an in it. Not a cheap pump by any means but they claim it flows within 1% bank to bank.

You must be registered for see images attach

 

[L31MaxExpress]

It's a knock sensor, not a temperature sensor. Vibration--the result of detonation pressure-spikes ringing the combustion chamber(s) like a bell (heard all the way in the passenger compartment as "Ping" or "Knock")--travels very nicely through iron.

And...GM being GM...the hole was already there, unused and plugged.


Infrared thermometers are notoriously inaccurate. Aside from largely being cheap Chinese, there's also the emissivity of paint to contend with.

I looked all over the Internet for a photo of that. I guess I wasn't using the right keywords. I read about this years if not decades ago, in the Chevy Power book, 8th Edition.
www.amazon.com/Chevrolet-Power-Prepare-Engines-Performance/dp/1557880875/ref=sr_1_1?

Water pump pressure side drilled for outlets, leading to the "siamesed" exhaust ports, adding coolant that doesn't have to squeeze through holes in the block/head gasket/cylinder head. I've also seen photos of the hoses leading from the block drains, where the cool coolant from the block is re-routed to the hot cylinder head, bypassing the head gasket.

But again...there's mods to the block deck and gasket that can also improve coolant flow there.

I have seen them plumbed from the pump to the block drains too. I have a feeling that was on a siamese bore engine like a 350 or 377 based off a 400 block. People did weird things trying to add cooling to siamese bore engines. I have seen them Y'd off to both the block drain and head as well. Depending on who built the engine and for what reason they had their theories I guess. I can say first hand though, high flow Flowkooler pump, high flow 195F thermostat and the 1003 Felpros have my 383 staying cool as can be even under sustained high loading. After changing head gaskets from the GM Vortec 0.028s to the 1003s my coolant temperature no longer shows a 20-30F spike in the coolant temperature reading on the dash gauge before the thermostat opens like it did before. The cylinder head definitely stays cooler where the dash gauge sending unit sits. Then again I also drilled two 1/8" holes in the 195F stat before installing it. The holes do not really change the warmup time either and prevent the crazy yoyo of coolant temperatures in cooler weather.

 

[Vettepilot]

Sounds like maybe the place to ask this...

I have always wondered about, and disliked, Chevy's idea of full time flow through the heater core. Personally, I do not like the idea of 200+ hot water inside the HVAC box competing with my poor air conditioning system. It gets to 130 degrees here all the time, so we take our A/C very, very seriously.

So, two questions:

1. Why did GM do this?

2. I rigged my new cooling system with a shutoff valve for the heater core. What problems might this engender??

Thanks!
Vettepilot

 

[L31MaxExpress]

Sounds like maybe the place to ask this...

I have always wondered about, and disliked, Chevy's idea of full time flow through the heater core. Personally, I do not like the idea of 200+ hot water inside the HVAC box competing with my poor air conditioning system. It gets to 130 degrees here all the time, so we take our A/C very, very seriously.

So, two questions:

1. Why did GM do this?

2. I rigged my new cooling system with a shutoff valve for the heater core. What problems might this engender??

Thanks!
Vettepilot

1.) They were too cheap to add them and the ones they did add were not overly effective.

2.) Not at all. Had both my vans the 1983 and the 1997 shut-off for over 6 months a year for years.

 

[Schurkey]

1. Why did GM do this?

General Rule of Society: If you have to ask "why"; the answer is always "money".

2. I rigged my new cooling system with a shutoff valve for the heater core. What problems might this engender??

Poor performance from the defroster would be the most-likely issue. And, of course, the heater is going to suck.

 

[1998_K1500_Sub]

I have always wondered about, and disliked, Chevy's idea of full time flow through the heater core.

So, ...

1. Why did GM do this?

My 1974 Pontiac GrandAm (400 cid / 6.6L) had a vacuum-operated coolant valve in the heater circuit, triggered by the max-AC setting on the temp slider control.

Some of the larger GMT400s came with valves too, the larger utility bodies certainly and maybe even the 2dr utilities. These were triggered by the "recirc" function, which can be engaged manually or (how many people know this?), on certain GMT400 model years (probably only those equipped with R134a) is automatically engaged whenever the AC high-side pressure exceeds ~350psi (see attached, from 1998 FSM).

 

[dtrader]

Vettepilot said:
I have always wondered about, and disliked, Chevy's idea of full time flow through the heater core.

So, ...

1. Why did GM do this?


Quoted from GM Service Manual: 1B-4

"The air conditioning system operates on the reheat
principle in that all the air passing through the system is
chilled almost to a freezing temperature and then
reheated to a more comfortable temperature before it is
discharged into the passenger compartment.
The dehumidified air is reheated as it passes through
the heater core in the air conditioning module. The heat
er is warmed by engine coolant passing through the
tubes of the heater core. This heat is transferred to the
heater core fins and given off to the air flowing past the
fins. The position of the air temperature valve in the air
conditioning module determines how much of the total
airflow is allowed to pass through the heater. In turn,
this determines the warmth of the total airflow dis
charged into the passenger compartment. The heater
water valve (on models so equipped) stops the flow of
coolant to front heater core under certain conditions.
This results in improved air conditioning system
performance."

James