Topic: RE: Found Drag Strip Near my House 750 times

[seanbarney41]

I played around with the calculator on the site I linked and I have a hunch it's estimating HP right off the crank rather than at the tire.

disagree...did two different calculations based off my times and came up with exactly what I would expect for rwhp

Honda's horsepower figures were supposedly at the crank, and were all over the map, over the years for the cb750.  I personally think, Honda was playing the numbers game with the buying public, the EPA, and Insurance companies  and that the difference in Honda's rated horsepower between say, a K1 and a K6, is largely due to insignificant tuning changes, such as timing, exhaust, and jetting.  By the time these old bikes get to us in the here and now, these tuning anomalies have all been changed, resulting in all year/model 750's being right in the ballpark of 65hp at the crank and 50hp at the rear wheel.

[Bailgang]

disagree...did two different calculations based off my times and came up with exactly what I would expect for rwhp

I sure hope not, by just estimating the bikes weight with me on it with an HP of 50 pretty much means I'm doomed to 14's.
I know what you mean by HP readings being all over the map, every web site I've gone to pretty much gives a different HP for my bike. I've never had mine on a scale to confirm it but it seems mine weighs around 558 lbs with gas and oil, add at least another 200 for me with riding gear on. Oh well we'll find out in a couple of weeks.

[seanbarney41]

disagree...did two different calculations based off my times and came up with exactly what I would expect for rwhp

I sure hope not, by just estimating the bikes weight with me on it with an HP of 50 pretty much means I'm doomed to 14's.

yup...the drag strip trip can really bring you back to reality after all the magazine articles, inflated factory hp figures, tall tales, and butt dynos

[Powderman]

I think any formula will only get you in the ballpark. There are too many variables that can change on each pass to give reliable results.
Wow, I just punched in some numbers to try it. My bike weighs 360lbs, if I weigh 170lbs that's 530lbs and if I make 100hp (I think it should at least), then my 1/4 mile time should be a 10.16 @133mph. The Sputhe Sportster featured on the cover of the July'80 CycleWorld ran the 1/4 mile in 10.55 @133mph with similar motor.

[Powderman]

disagree...did two different calculations based off my times and came up with exactly what I would expect for rwhp

I sure hope not, by just estimating the bikes weight with me on it with an HP of 50 pretty much means I'm doomed to 14's.

yup...the drag strip trip can really bring you back to reality after all the magazine articles, inflated factory hp figures, tall tales, and butt dynos

I had a 1978 Plymouth Volare' Super Coupe with a Police Option 360 package. Ran blistering 16.80's with it. Ya, what you thought was fast goes away real quick when you are around real race stuff.

[Bailgang]

disagree...did two different calculations based off my times and came up with exactly what I would expect for rwhp

I sure hope not, by just estimating the bikes weight with me on it with an HP of 50 pretty much means I'm doomed to 14's.

yup...the drag strip trip can really bring you back to reality after all the magazine articles, inflated factory hp figures, tall tales, and butt dynos

I had a 1978 Plymouth Volare' Super Coupe with a Police Option 360 package. Ran blistering 16.80's with it. Ya, what you thought was fast goes away real quick when you are around real race stuff.

I hear you on that, I thought my 78 Trans Am that I had many moons ago was a missile until the first time I took it to the strip, low 15's if I remember correctly. Dyno's can be a reality check as well, I knew my 750 wasn't in optimal form at the time but the 47 HP that showed on the dyno last year had me bummed. Maybe the dyno operator was trying to cheer me up when he told me mine put out the most power of any vintage bike he had on the dyno but the first though that came to my mind was "geez, you must get a lot of clunkers in here then". That shop charged $40 for a dyno pull with exhaust analyzer, the problem is since then they've sold their dyno and the only other nearby shop with a dyno wants $100 to do the same. The drag strip will tell the tale this time around.

[seanbarney41]

If you can go there on a slow night, the strip is the best place to do tuning/plug chops...

[Bailgang]

Well today is the big day and the excuses may already be starting. My youngest son showed up yesterday with his WRX and immediately popped the hood, apparently its loosing boost pressure and getting 16.5 lbs of boost when it should be around 18.5  and he's loosing it at the rubber coupling where the intercooler connects to the intake. He thought he took care of it last night but I guess it's loosing it again, I told him he better think of something because NO EXCUSES will be allowed if his Uncle's Mustang beats him. Unfortunately on the other hand my oldest son wasn't able to bring his 73 750 because he couldn't find a trailer to haul it here, it's too long of a story to explain right now why he couldn't have just ridden it here but he will be there at the track with us anyhow. On the other hand a nephew of mine in Illinois decided he wasn't going to just set back and hear about his Uncles and cousin having all the fun and has instead decided to join the fun with us and bringing his front engine small block chevy powered 67 Corvair to tangle with us. I've got my 750 all set to go, my only fear is that I hope I don't tear it up too bad because it's clutch will be taking a beating. I'll start another thread with the results so I don't hijack this thread any further.

[Restoration Fan]

Good luck today.  Go whip the pants off the "car boys".  Oh yeah...my money's on the Corvair.....to come in last. 

[Bailgang]

The Corvair turns a high 12 but that's with the help of a 70 hp shot of nitrous, low to mid 13's without it. Not too shabby but I think it should be in the 12's without the bottle.

[chewbacca5000]

Sounds like fun bailgang,  Better represent!

[Powderman]

Like to see pics of the Corvair conversion, don't see too many with front engine. I inherited a 65 Corvair with a Toronado V8 in the back this year. I imagine all it's good for is drag racing and wheelies with all that weight hanging off the back.

[Bailgang]

Like to see pics of the Corsair conversion, don't see too many with front engine. I inherited a 65 Corvair with a Toronado V8 in the back this year. I imagine all it's good for is drag racing and wheelies with all that weight hanging off the back.

I'll have to dig around later for pics of the Corvair but here's a link describing yesterdays event. http://forums.sohc4.net/index.php/topic,150642.0.html#msg1719270 I haven't uploaded any vids yet from my camera either just yet but I will later on in that new thread.

[Powderman]

Like to see pics of the Corsair conversion, don't see too many with front engine. I inherited a 65 Corvair with a Toronado V8 in the back this year. I imagine all it's good for is drag racing and wheelies with all that weight hanging off the back.

I'll have to dig around later for pics of the Corvair but here's a link describing yesterdays event. http://forums.sohc4.net/index.php/topic,150642.0.html#msg1719270 I haven't uploaded any vids yet from my camera either just yet but I will later on in that new thread.

Please do, I'm seriously interested in seeing them.