Dave Robsons Challenger R/T

Dave-R · Post by **Dave-R** » Wed Aug 04, 10 11:12 am

OK so the car ran 12.2 @ 110mph at Santa Pod Raceway.

I also got it accuratly weighed by Jon which was interesting.

Total weight of car with slicks and full tank of fuel was 3705lbs.

Total race weight with me in the car was 3890lbs.

Front - Rear weight is split 54.9% - 45.1% (pretty good for an iron head big block car I think).

Side to side weight distribution is 50.8% Left and 49.2% Right.

Using the race weight and timing slips to work out rear wheel HP indicates something like 420HP at the wheels on that day.

AllKiller · Post by **AllKiller** » Wed Aug 04, 10 5:41 pm

Sounds right to me Dave mine was similar running 12.4's minus the gas,
a 50hp shot pushes it on to 12.00 deads

My calculator said 420hp and 450 hp to run 11.9...about 535hp at the crank in a 383.

Dave-R · Post by **Dave-R** » Wed Aug 04, 10 6:15 pm

It used to run 113mph in the quarter which is just over 440 rear wheel HP. That was with the old hydraulic lifter cam. But this solid should have about 25hp more?

Jon Connolly · Post by **Jon Connolly** » Wed Aug 04, 10 7:19 pm

Car looked good Dave

Don`t forget all the front end pulley driven stuff will be having a draining effect ( power steering / water pump / alternator )

Could always get a 2nd belt just for the track sized to run just the water pump

Dave-R · Post by **Dave-R** » Wed Aug 04, 10 9:08 pm

Power steering???

Got an undersize crank pully which is why the alterator does not charge very well at idle.

Mick70RR · Post by **Mick70RR** » Wed Aug 04, 10 9:52 pm

I don't believe there is a percentage HP loss through the drivetrain. The HP required to overcome the friction of the drivetrain would surely be the same whether there was a 300HP engine or a 500HP engine under the hood. Figures I have seen are 25HP for an auto and 15HP for a manual.

Roger · Post by **Roger** » Wed Aug 04, 10 10:33 pm

Mick70RR wrote:I don't believe there is a percentage HP loss through the drivetrain. The HP required to overcome the friction of the drivetrain would surely be the same whether there was a 300HP engine or a 500HP engine under the hood. Figures I have seen are 25HP for an auto and 15HP for a manual.

There is. And its not linear either.

AllKiller · Post by **AllKiller** » Thu Aug 05, 10 8:58 am

Have your 906's got the bigger valves ? possibly like me, you've hit the 906 capability.... without serious porting.

Dave-R · Post by **Dave-R** » Thu Aug 05, 10 10:13 am

AllKiller wrote:Have your 906's got the bigger valves ? possibly like me, you've hit the 906 capability.... without serious porting.

Yes they have bigger valves. They are not "Seriously Ported" but flow better than stock Stealth heads.

906-------IN----------EX
0.500 --- 258 ------- 201
0.550 --- 262 ------- 204
0.600 --- 258 ------- 208

AllKiller · Post by **AllKiller** » Thu Aug 05, 10 12:53 pm

Christ they are good

Dave-R · Post by **Dave-R** » Thu Aug 05, 10 2:29 pm

The suspect head is at the engineering works for a vacuum test. There was no visable sign of a crack.

This is not the same head that was repaired by Hughes Engines that had a crack below the two center exhaust ports. I thought it was but that one is on the other side of the engine.

Dave-R · Post by **Dave-R** » Thu Aug 05, 10 2:38 pm

Found why the tyre went flat on the M1. Dug this out of the tread.

Dave-R · Post by **Dave-R** » Thu Aug 05, 10 2:40 pm

This is the inside face of the header gasket. The side that faces the head.

The two outer ports have no sign of any kind of leak from the port or bolt hole.

Dave-R · Post by **Dave-R** » Thu Aug 05, 10 2:41 pm

This however is the area I hear water boiling. There is no staining around the bolt holes but lots of staining along the bottom edge and between the ports. There is rust along the very bottom edge.