Dragbug engine/head temps

[Bruce67]

Hey guys, I recently bought a drag bug and I am looking for some info on engine temps. How much heat should I have in the motor before a run and what kind of head temps should I see at the end of a run and what is cool enough to run again? What is considered too much heat? Motor is a 78x94, superflows, ida's, 14:1, fk89. Looking for actual numbers. Any help is appreciated. Thanks alot--Bruce.

[Neil Davies]

Difficult to give exact numbers, as I can't even remember f my gauges were in C or F, but I always tried to run the car up in the pits first to get some temperature in the oil, but then let the motor cool down for a little while to get the heat out of the heads. I liked the heads to be cool enough to touch, but you can still feel that they're warm if that makes any sense?

[Bruce67]

Neil, that makes perfect sense. That will give me an idea of where I need to be. Head temps go up fast just idling, cant imagine what they will be at the end of a run... Thanks for your reply...

[jaqo]

I'm also interested about it  - what temp is dangerous for heads?

[Airspeed]

I'm also interested about it  - what temp is dangerous for heads?

You think there is a generic number for heads in general?

[Bruce67]

I would imagine that there is a generic number for stock and very mild heads, but worked heads in a hi-po street car and certainly in a drag car, have got to be much higher. This must be a big secret or nobody knows...Come on drag guys, chime in...Seems like plenty of others are interested in knowing this as well...

[bugnut68]

I'm also interested about it  - what temp is dangerous for heads?

It was always my understanding/impression that valve seats start to come loose when you have extended head temps of 400 degrees or higher... I don't have personal experience, but that's what I recall reading when I asked the same question before installing a head temperature gauge.

[jaqo]

I'm also interested about it  - what temp is dangerous for heads?

It was always my understanding/impression that valve seats start to come loose when you have extended head temps of 400 degrees or higher... I don't have personal experience, but that's what I recall reading when I asked the same question before installing a head temperature gauge.

Thanks.

[funnycarmike]

It's been a looooong time since I raced a VW but if my memory is correct, 350 on the head temp. was the "norm" after a run.  On a hot day (100 + degerees) it was not uncommon to see 375 degerees for the head temps.  I would always get nervous at 375.  I would always warm-up in the pits and then let cool before a pass.  As for oil temp., I can't remember what the actual # was.  Oil temp. never was an issue though, I was always keeping an eye on the head temp.

[TexasTom]

It's been a looooong time since I raced a VW but if my memory is correct, 350 on the head temp. was the "norm" after a run.  On a hot day (100 + degerees) it was not uncommon to see 375 degerees for the head temps.  I would always get nervous at 375.  I would always warm-up in the pits and then let cool before a pass.  As for oil temp., I can't remember what the actual # was.  Oil temp. never was an issue though, I was always keeping an eye on the head temp.

This was my experience and ritual as well, almost exactly.
Anything over 375 and I got nervous. Either pretty hot outside or running too lean ...
When I run my streetcar now, I run the generator as a motor by grounding the feild to evacuate the hot air so it doesn't bake. Then at the end of the track, flip the switch back, put the belt on and drive back to the pits ... keeps it under control pretty well.
On the race car, I didn't run tin at all since their were no barrel fins, but I did keep an eye on the head temp ...
TxT

[Bruce67]

Just letting my drag car warm up for 3 to 4 minutes sees 230+ on the heads, using a temp gun. I have had a few other people suggest warming up for a few minutes then let cool down to where you can touch the heads without getting burned, but they still have some heat in them. Then its ready for a run. Seems like after a burn out, staging, waiting for the other guy, and full throttle 8,000 rpm shifts for a quarter mile, with no fan, are going to put the heads temps into the stratosphere...I guess I will have to see what my temps are at the end of a run and go from there...

[funnycarmike]

Bruce, I think that is normal.  Mine would heat up extremely fast as well.  But you also need to remember that on a run, the fuel dumping in at wide open throttle keeps the head temp. from climbing.  Then when you shut it off, the temp climbs again.

[Bruce67]

Thats a good point Mike, never thought about that. I do have 2 electric fans mounted on the motor to help cool things down a bit after a run. I remember reading some time ago how some guys would heat the oil outside of the engine with a hot plate then add the oil just before a run. I would assume this was to have the motor as cool as possible to make the most power but the hot oil provided the needed oillling in the motor. What would be too hot? How could you tell?