throttle body bypass

[Scrrem]

Originally Posted by max76

Wow...very very nice job!!!!
Beautiful view if your engine..i'll like to do the mine too!!!
Here in Italy i think is impossible to do it!!!!!!
Do you remove also the alluminium hose of the plenum...i'll put a rubber for close the hole, it's ok??

Thanks...I would just cap off the nipples. Trying to remove the aluminum fittings is a pain and if you damage them you can't find them anymore, so I would just leave them alone.

Rich

[XfireZ51]

Originally Posted by max76

Wow...very very nice job!!!!
Beautiful view if your engine..i'll like to do the mine too!!!
Here in Italy i think is impossible to do it!!!!!!
Do you remove also the alluminium hose of the plenum...i'll put a rubber for close the hole, it's ok??

Max,

The coolant continues to circulate, it just bypasses the Throttle body, so you leave everything in place. I have my coolant passages blocked off at the Injector Housing so I can pull the plenum without needing to drain the coolant. I had the Haibeck bypass but it became unecessary after blocking the passages.

Ciao,

Dominic

[max76]

Originally Posted by XfireZ51

Max,

The coolant continues to circulate, it just bypasses the Throttle body, so you leave everything in place. I have my coolant passages blocked off at the Injector Housing so I can pull the plenum without needing to drain the coolant. I had the Haibeck bypass but it became unecessary after blocking the passages.

Ciao,

Dominic

Thanks Dom,
ok...i'll do the modify and i'll close the nipples. So, the rest of the cooling sistem is right..ok???
So, why they do pass the water in the plenum?What's the function?
If you block the water what's happen?
Thanks
Max

[Kevin]

it's to keep things from freezing when you drive in cold weather...but who drives their zr-1 in cold weather

[max76]

also the plenum it's keep hot for the winter???
it's a strange solution...
sure my z is running only with nice weather, in winter it don't takes rain, snow or ice!!!
;-)

[scottfab]

Originally Posted by max76

also the plenum it's keep hot for the winter???
it's a strange solution...
sure my z is running only with nice weather, in winter it don't takes rain, snow or ice!!!
;-)

Although someone has tested for icing at 20 deg and 90% humidity without problems this does not guarantee an LT5 will not self destruct when going from a garage of relatively low humidity to an outside condition of (worst case) 32deg and >75% humidity. As I recall a few engines were lost in initial testing this way. For the vast majority of us this is not an issue because of the climate and/or seasonal driving we do. The GM solution for "icing" was to route water thought the plenum.

[Paul Workman]

Couple things to add...

Marc and I were discussing the possibility of the TB freezing, but If I recall correctly, Marc has driven in sub Zero (F) w/o problems, and I have driven my car at speed when the temps were -10 to -15º C with NO problems with freezing up. I don't know what the humidity was, but probably not very high on any of a few cases. Marc made the comment that if one waits until the engine gets up to operating temperature, there should be no problem with freezing, except in extreme cold conditions, maybe.

The other thing worth mentioning was after Marc plugged the coolant passages in the injector housings, he had trouble with an air lock and the motor wanted to over heat. As result, Marc no longer will plug the IHs, but rather will run a bypass hose between the nipples on each IH.

Well, I'll keep a sharp eye on that in the future, but I really like not having to fuss with coolant draining and that mess any time I want to pull the plenum for any reason. Not fussing with that coolant makes it just a little more involved than pulling a carb! I've never had a problem after plugging the passages in my IHs, but after reinstalling my heads and the IHs and plenum, I used a long neck funnel to fill the block and the IHs from the ports on the sides of the IHs, before connecting the coolant tubes..."just because" it seemed like a good idea at the time.

As far as performance goes, I don't think it hurts, but I've not seen anyone put a number to it. However, the few times I've felt the plenum, it feels to me to run much cooler than before. Cooler is usually better when it comes to performance, so bypassing the TB is not going to hurt performance, I guess.

P.

[scottfab]

I know icing on the leading edge of an airplane does not always happen at low temps either. I'm sure glad the designers assume it will and make the proper decision. But I suppose ah who cares if it's just an LT5 that blows. No biggie.

[Paul Workman]

Originally Posted by scottfab

I know icing on the leading edge of an airplane does not always happen at low temps either. I'm sure glad the designers assume it will and make the proper decision. But I suppose ah who cares if it's just an LT5 that blows. No biggie.

Oh, please...