The car loses power on the second pass.

[SteveSS]

We were running the 71 Challenger at the track today. It's just a 1/8 mile. It has a 408 stroker from BluePrint Engines. On The first pass, it does great. It was not a hot day. Maybe 80 degrees at the most. Coming around for the second pass we had to wait in line between 5 to 10 minutes. We turned off the engine whenever we could. It would heat up but not terrible. The second pass is way down on power. Shifting to second gear the engine bogs terribly, hardly any power even feathering the throttle. After letting the car cool down for 45 minutes it's back to good power then the second pass is crappy. What's going on?

 

[padam]

I just talked to a guy at the track today who had a similar issue, turned out to be his torque converter

 

[496 polara]

Fuel issue? Vapor lock?

 

[33 IMP]

Agree with 496 polara. IMO, Fuel delivery issue. Got a fuel pressure gauge on it?
Mechanical pump, or electric?

 

[Paul_B]

Fuel issue? Vapor lock?

Vapor lock was one of my thoughts too.

 

[Kern Dog]

Torque converter?

Nah… more likely the tire valve stem caps.

 

[WileERobby]

Above ^^ are my thoughts also. Fuel lines insulated ?

 

[QuickBpBp]

Sounds like a fuel issue to me. It should actually go faster on the second pass as everything is warm and thin which takes less horsepower to spin it…

 

[SteveSS]

It's a 4-speed. Mechanical pump.

 

[RemCharger]

Mechanical fuel pump= gasoline heater.
Hot gas=bad.

 

[66 Sat]

Probably fuel, but also could be ignition related. My old 351 cleveland used to do this at the track. Fine on the street but at the track by the 2nd or 3rd run it would die off and lose power. I never found out the specific issue but it went away after changing plug leads, distributor cap, rotor arm, coil etc.

 

[padam]

Ok pretty stupid of me to recommend torque converter on a 4 speed.
Guy I talked to put $1k into his fuel system trying to fix it.
Just spit balling.

I guess I was still a little punchy from the beating I took.

 

[QuickBpBp]

It's a 4-speed. Mechanical pump.

Clutch slipping when hot?

 

[R413]

Did you ever open the hood while waiting in line?
You have got to let that heat out.

Real racecars have electric fan and water pump so they are cooling just fine with the hood closed, but not a street car with belt driven fan and pump.

 

[SteveSS]

It's not slipping at all. It just bogs down dramatically. It did okay in first, then right after shifting into second 90% loss of power.

On the lighter side even though it was a fairly cool day for summer the sun can be wicked dangerous at this elevation. I think Pikes Peak International Raceway is 6,000 feet above MSL. Both my son and I tend to wear cowboy hats as protection. When the car was on one of its first passes when he hit second it was enough G's for my hat to fly off.

 

[QuickBpBp]

It's not slipping at all. It just bogs down dramatically. It did okay in first, then right after shifting into second 90% loss of power.

On the lighter side even though it was a fairly cool day for summer the sun can be wicked dangerous at this elevation. I think Pikes Peak International Raceway is 6,000 feet above MSL. Both my son and I tend to wear cowboy hats as protection. When the car was on one of its first passes when he hit second it was enough G's for my hat to fly off.

You are wearing cowboy hats while drag racing? You are a passenger while your son is racing? That would not fly at any of the tracks I raced at...

 

[RemCharger]

You are wearing cowboy hats while drag racing? You are a passenger while your son is racing? That would not fly at any of the tracks I raced at...

Has to to be 14.0 or slower.

 

[QuickBpBp]

Has to to be 14.0 or slower.

Yep probably right...but I would think a 408 stroker would be somewhere in the 11's or what an equivalent time in the 1/8 would be...

 

[SteveSS]

Rules are extremely lax at Pikes Peak Intl' Raceway. No inspections. Just line up and go. I saw several cars with the whole family in the car just having a good 'ol time. The scary part is the high banked oval. The drag strip is the normal pit lane. 1/8th mile drag then 1/8th mile slowdown then you merge with cars going fast around the oval some doing 100mph. You merge with them, go around once then exit to pit lane to race again. See video. I told you it's a crazy show.

 

[kiwigtx]

How close to God are you Steve ? - your elevation might be an issue.

High elevation combined with heat soak.