starting car without header?

[mikecb7LX92]

i got some friends that sometimes when they swap motors, they turn them on without the header to see if the motor is any good, isnt there any consequences to this? i always thought that if you were to do that, that it would burn the valves.

[Tippey764]

I hear it can burn valves if you run it too long, I mean you could start it up for a second or two without and problems, i've done it before but i wouldn't run for any longer without them on there. Now i know for a fact you can run with a header but not a downpipe and its perfectly fine.

[mndude07]

Don't do it. Terrible things can potentially happen. You need AT LEAST the upper portion of the header on there.

[stretch JDM]

you can crank it but shut it off quickly.as stated above it will warp the valves , but not in a short time.

[Alex 90DX]

why would even do that?? its not worth it just do straight header if u wanna hear the sound it makes

[19dabeast85]

why would even do that?? its not worth it just do straight header if u wanna hear the sound it makes

Um....because they wanted to test run the engine before fully installing it as was stated in the original post.

As stated before, it's not recommend by any means, but 10 seconds won't burn your valves. Don't run it any longer than that though.

[iwork4mycb7]

i think if best way to test a motor is to take out spark plug one by one.

[GeoffM]

I had a friend with an engine class in school. They ran a big V8 without headers. Burned all the valves.

[Alex 90DX]

Um....because they wanted to test run the engine before fully installing it as was stated in the original post.

As stated before, it's not recommend by any means, but 10 seconds won't burn your valves. Don't run it any longer than that though.

ohhh im so sorry! i was fucked up this morning when i saw this thread.
speed reading

[yaboi jeff]

dont do it bro not to mention the complaints of your neighbors and if the cops hear it theyll be hatin big time just sayin.

[mikecb7LX92]

yea i kinda figured that it would burn the valves, i was wondering if it was true or not...thanx for the info guys.

[kellogg_racing_]

Think about it. Your valves are going to get really hot from the combustion process. Then the COLD (compared to the temp of the valves) air will rush right in from the opening in the head. That kind of temperature change will warp the valves. It's going from very hot to very cold in a very short matter of time. Remember metal contracts and expands when it gets hot and cold. To address the above statements, even doing it with the upper portion of the header is dangerous if longer than say 15 seconds. But don't do it without the upper portion EVER. I know it's been solved, but this is the reason behind it!