Hey people,
Just a quick question. On a 454 BBC you have the hose that goes from the water pump to the inlet manifold (with an aluminium inlet manifold). I am guessing this returns water from the block back to the inlet side of the water pump, bypassing the thermostat?
If this is the case surely even once the stat is open some of the coolant is going to return through this pipe rather than goind through the radiator and being cooled? This must result in a higher running temp? Is it advisable and can this pipe be removed and plugged? What are the pro's and cons of doing this?

Oh one more quick one, with Hedman headers and a straight through system would 2.5 inch pipework be enough or would it be worth going to 3 inch?

Cheers people,
Lester

 

just for starters
http://forums.corvetteforum.com/c3-t...pass-line.html

i also saw a chart out there where dual 2.5 inch exhaust flowed enough air to work with an engine up to 500hp. no idea as to the validity

 

the con in plugging the by pass is if your stat sticks closed you still have some circulation to the rad and although it will over heat it will not melt anything..the pro for the by pass is faster warm up's...the fact it does bleed some coolant to the pump is of no concern as it is shed back into the lower part of the block and then re circulated which is ideal for a street engine, also the by pass helps with air pockets in the system .......

 

I can not explain what was going on with my temp readings when I removed the bypass line.

It was recomended form some members here that have a lot of knowledge of cooling systems to remove it and I did but the temps would swing.

I think my issue may have been the water pump that I'm runing, its a Stewart high flow pump. I think without the bypass line the pump was cavitating.

Neal

 

the bypass lets water circulate thru the engine before the 'stat opens. blocked, is the same as removing the belt on the WP (unless the heater has an open valve, then it will circulate thru the heater core) so it will warm up real fast IF u use a heater control valve on the bypass, and always remember to open it once it warms, say, 125-180F. Temps may soar if u plug it or forget to open a valve.
The reason for faster warm-up is WAY WAY better MPG. My tests show cold starts in summer use more than twice the gas in the 1st mile or 2. Expect worse in winter, unless u can get the heads warm real fast.
.
It would be an interesting experiment to close a valve once the 'stat opens; that would put more flow thru the rad and could in theory help cooling at idle when flow is weak
an alternative would be to reduce the size, say, down to 0.3" then less is diverted and u can't forget. i don't know the best size. Also turning on the heat w/blower will improve cooling in an overheating emergency

 

The stock pump has at least 35% margin even at idle, so flow is NEVER a problem.

 

I have to ask are you having an over heating problem and "thinking" blocking the bypass will fix it ?

 

with this same theory in mind I added two aluminum heater cores up in the front bumper behind the grills and ran the bypass line through them. This way the bypass line will also help with cooling.

Here's a pic before putting the front back together:

http://img.villagephotos.com/p/2006-...7/P0000051.JPG

 

That is a cool set-up! But i'd plumb it thru the thermostat housing neck(drill &tap 1/2NPT 5/8barb), return thru a T at the heater hose at the WP. (not the bypass). Could use a heater control valve to turn it on when needed, or it would just flow when the stat opened. This way u keep the stock warmup ability. And as Mike said, there is plenty of pump flow.

 

after looking over the system the pressure break point is the T-Stat. If its placed after the T-stat it will not function as intended. Both attachment points would be on the low pressure side of the system.

I had trouble keeping my car cool in the past so I wasn't to worried about it not warming up.

It doesn't appear to have had a significant effect on the warm up time.

Neal

 

Neal
i should have expected that. an engine as hard to cool as yours is going to warm up fast. i remember Norval w/blown BB didnt even run a 'stat, there was so much friction from the blower it warmed up fine.

 

Hi

Funny thing is that some SB do not have this bypass hose. The basic setup of the engine is the same as the BB, so why can a SB live without it ?
A BB car without AC has a constant bypass through the cabin heater anyway. With AC, there is a S/O valve.
So , BB without AC, removing the water pump bypass should not harm in any way.

I kept both installed, the water pump bypass + the heater and the eng temp sits at the thermostat temp ( depending which one I use ). Had a 160 F ( way too cool ), presently a 195 F. OK, but interfers with my electric fan thermostat, so will install a 180 F for trial.

If you remove the bypasses, you must drill a couple of small holes into the thermostat in order to avoid hot spots in the engine during warm up, when the thermostat is cold.

Rgds. Günther

 

All SB have an internal bypass. It is built into the water pump and a passage in the block. It is about 0.37". One less hose to buy, 2 less clamps. Kudos to the bean counters
An efficient engine, like mine, would take 7+ miles to fully warmup with holes drilled in the 'stat. I had a 'stat like that years ago, and had to fill in the holes to get decent heat in winter, about 1.5 miles instead of 5-7.

 

Thanks for all the replies guys. It gives me plenty of food for thought.
The engine has never run yet, so I have no idea if I have overheating problems yet.

Having never had a BB the bypass hose was all new to me, and is replacing the SB that used to be in the Vette, hence the reason for the question.
I have no real need to remove the bypass hose, but was just interested on everyones thoughts on it. My only concern was that the water could potentially take the easiest route and go through the bypass hose rather than the rad. Having now thought about it you sure as hell arent going to return the majority of the water through that little hose rather than the radiator hose.
So in theory I am better off keeping the bypass hose to aid quick warm up and allow flow until the stat opens (although I have flow through the heater core anyway), unless of course the engine runs on the hot side in which case its worth sacraficing the quick warm up for the aided cooling of plugging it once up to temperature.
Does the above make sense or have I misunderstood?

So that you have the full picture I have a 77 Vette, It used to be an L82, but is now being replaced by a new (old stock) LS6 454. I have fitted under drive pulleys with a high flow Edelbrock aluminium water pump. I have removed the A/C but kept the heater core (Its more often cold than hot in the UK!) and have no shut off valve to the hater core. I am also fitting a new aluminium radiator. I have twin 12inch elcetric fans which on the SBC made it run too cool with a standard rad so one is on a stat and the other is manually switched.

Thanks again for your help. Oh and with regards to the exhaust's, after further research I will probably go for a 2.5inch system.

Thanks again,
Lester

 

Wow - That is one nice set up! Hopefully I wont need to do it, but if I do have trouble with temperature I now have an idea on where I can mount additional rads to cure it!