where should the power be?

[fastman614]

Dr G-

He is an old drag racer and disputes the idea that our motor is built on, that you need all the power you can get at the revs in top gear that equate to the speed you are trying to achieve. His argument is it should be in the middle of the range where he contends the motor will spend most of it's time.

Is the use of the term - he is an old drag racer - in reference to his present age and inferring that he is still an active racer or is it reference to his having formerly, in years gone by, a drag racer?

From someone who is also "an old drag racer" (me - and, actually, in both senses of the meaning -ask my grandkids and they will tell you that I am as old as "dirt")) .... Either way, here is one to turn the discussion into interesting- Over the decades, from the 50s on, drag racers found that the use of a 2 speed and/or a 3 speed transmission offered an advantage over no transmission (top fuel and lower class dragster with lenco's, clutchfights etc).... and subsequent to that, discovered that a 4 speed and then a 5 speed transmission offered ever greater advantages (stock, superstock, modified, gasser, altered, prostock etc...) the reason why?.... because, even in drag racing, falling too far out of the power band has detrimental effects on elapsed times... and having multi-speed transmissions kept the power up in the "sweet spot" or much closer to it anyway, thus resulting in quicker elapsed times....

[Bob Drury]

  I can hardly wait (literaly speaking, for God's sake) for my heirs and the bankers to discover that I blew it all and then some !
  And for the last act, set a record, get a hat, rent a Hot Tub Suite at the Montego, Hire two Hookers, Uncork the Bubbly, Fire up the most expensive Cigar that I can find (in memory of Courney) and "Shoot for the Moon (once again literaly speaking, of course)"....................  and No, I won't be requesting a Champagne B.J., as I have it on good authority that they are overated..........   Well on second thought, Why Not?  I never have listened to anyone else's advice anyway.............
                                        Bob    

[Stan Back]

It's good to see you're staying up with the times -- moving from the Stateline to the Montego.

[SPARKY]

Sparky - How BIG IS that engine?.... low 4s on your shift out of low.... sweet spot at 6250.... I have a hard time relating to this as all of our engines are 3.25 to 3.3 inch stroke screamers - even our 432" big block - which makes its horsepower way up in the eights....

it is a 565 with some old Brodix 2x extra heads -- the torque curve is rather flat above 5800 and peak hp is only 7250 because I NEED some new 12  deg. Brodix "man eaters"  lol heads.

 I need to be making power up in the 8s. I might be able to pull what I have---that is why I built a new car---the old one was up against the AERO wall with my gearing and engine

[SPARKY]

Dave, you are spot on about the extra gears, and accleleration ---I would buy one of John Kilgores special geared AT 400s if I were to continue to run NA--  but I will go to the small BJs most likely

[interested bystander]

Pardon a return to the subject.

   'Couple pretty successful Lakes, Bonneville, racers have told me "Build the engine like a Sprint Car motor", or  "like a road racing engine".

  Should give a clue as where the power band should be.

[fastman614]

Pardon a return to the subject.

   'Couple pretty successful Lakes, Bonneville, racers have told me "Build the engine like a Sprint Car motor", or  "like a road racing engine".

  Should give a clue as where the power band should be.

I have thought about this for several days now.... sprint car, I can agree with ... road race - not quite so much - although pretty close, as they are generally built a bit less peaky than sprint car motors...

My own opinion is that a Bonneville motor should be a "hybrid" built by using the best that NASCAR can offer and using it in a drag race engine.... the fact is that our most recent engines are slightly modified and "uptuned" NASCAR engines....

Neil Thompson (rest his soul) told us decades ago that setting any of the faster records is like running a 5 mile long drag race - get on it as hard as you can, as quickly as you can and stay on it for the whole 5 miles! He said that was his "secret" away back in the 60s when he was the "owner" of pretty well ALL of the comp coupe records .... there was one other thing too - make sure that you build the car to have traction that will keep the car "hooked up" ....

[jl222]

 

  I've seen some fast cars push off for a long distance and thought ''is the push truck faster than the race car?''

   El Mirage is were you really want to get with the program as it is easier to gain mph at the start were track
is going by slower.

      JL222

[fastman614]

  I've seen some fast cars push off for a long distance and thought ''is the push truck faster than the race car?''

   El Mirage is were you really want to get with the program as it is easier to gain mph at the start were track
is going by slower.

      JL222

It is really difficult to say whether one method is "head and shoulders above" or in any way better than the other....

With the tight gear spacing in the lakester transmission, we, throughout 2010, pushed the car to about 70mph, which took to almost the 1/2 mile mark. The truck was almost powering out at that point. If anything in the way of a benefit was achieved by doing so, it is debatable. Yes, we ended up setting the record in the class that year .... and the car achieved a 2 1/4 mile speed of 251 mph on its best run.

We had several discussions about this very topic - specifically because we were asked why we pushed the car so far before launching....

In 2011, we decided to "test launch" the the car at a slower speed - with the 1/4 mile mark being the agreed upon launch point - a point at which the truck was going about 40mph. We paced the car for about 300 feet under full throttle and the car was pulling away. We were also accelerating the truck faster than if we were actually pushing the car at this time. We had pretty much "proven" to ourselves that the car, with the tall gearing, was still capable of accelerating through the 1/4 mile to the 1/2 faster than if we pushed it with the truck....We did NOT achieve a faster 2 1/4 mile speed though - going "only" a fastest of 246mph (5mph slower)... However, we did manage to set the record up another mile per hour from the year before anyway, as the car gained 30mph from the 2 1/4 mile to the 5 mile instead of "only" 24mph in the same distance as per the year before.

Did the difference in the distance that we pushed the car make a difference to the outcome?.... I don't know....

[wobblywalrus]

Pages and pages of calcs and many late nights figuring, using gear ratios, tractive force, drag, etc., combined with all sorts of runs on the salt, shows me two things.  Power at the top end is most important with enough mid range to carry you through the shift into top gear without bogging the engine.

[fastman614]

Pages and pages of calcs and many late nights figuring, using gear ratios, tractive force, drag, etc., combined with all sorts of runs on the salt, shows me two things.  Power at the top end is most important with enough mid range to carry you through the shift into top gear without bogging the engine.

And who hasn't done pretty much this?

I was told one thing a very long time ago - I do not remember precisely how it was said but it was to the effect that power increase at a rate of 100% of the percentage of nitro being added and perhaps a bit more...

It must have been interesting back in the day when in the "fuel only" classes, they'd start out with a "conservative" fuel mix and go up from there...

[jl222]

  I've seen some fast cars push off for a long distance and thought ''is the push truck faster than the race car?''

   El Mirage is were you really want to get with the program as it is easier to gain mph at the start were track
is going by slower.

      JL222

It is really difficult to say whether one method is "head and shoulders above" or in any way better than the other....

With the tight gear spacing in the lakester transmission, we, throughout 2010, pushed the car to about 70mph, which took to almost the 1/2 mile mark. The truck was almost powering out at that point. If anything in the way of a benefit was achieved by doing so, it is debatable. Yes, we ended up setting the record in the class that year .... and the car achieved a 2 1/4 mile speed of 251 mph on its best run.

We had several discussions about this very topic - specifically because we were asked why we pushed the car so far before launching....

In 2011, we decided to "test launch" the the car at a slower speed - with the 1/4 mile mark being the agreed upon launch point - a point at which the truck was going about 40mph. We paced the car for about 300 feet under full throttle and the car was pulling away. We were also accelerating the truck faster than if we were actually pushing the car at this time. We had pretty much "proven" to ourselves that the car, with the tall gearing, was still capable of accelerating through the 1/4 mile to the 1/2 faster than if we pushed it with the truck....We did NOT achieve a faster 2 1/4 mile speed though - going "only" a fastest of 246mph (5mph slower)... However, we did manage to set the record up another mile per hour from the year before anyway, as the car gained 30mph from the 2 1/4 mile to the 5 mile instead of "only" 24mph in the same distance as per the year before.

Did the difference in the distance that we pushed the car make a difference to the outcome?.... I don't know....

  Not hard to figure out that if your going faster at the  1/8 mile mark or 1/2 mile you will be going faster at the 21/4, if not
your gearing is to high in the lower gears or can't hook up'

 I'm talking cars with enough hp to be going faster after the 3 mile.

 It's like starting at the drags at 1/2 track, you think you should have the same speed?

 NHRA shortend the track to 1000' from 1320' to keep the speeds down for the top fuel cars.

               JL222

[fastman614]

  Not hard to figure out that if your going faster at the  1/8 mile mark or 1/2 mile you will be going faster at the 21/4, if not
your gearing is to high in the lower gears or can't hook up'

 I'm talking cars with enough hp to be going faster after the 3 mile.

 It's like starting at the drags at 1/2 track, you think you should have the same speed?

 NHRA shortend the track to 1000' from 1320' to keep the speeds down for the top fuel cars.

               JL222

Well.... easy to say so, I guess .... we did have two (perhaps 3) variables - a different driver and a rear end gear ratio change of about 3% taller.... So, possibly Ed did not get on it as aggressively as Cal did the year before and possibly the slightly taller gearing dragged out the acceleration a bit (possibly also was that we set the record at the W/Fs in October air and we were trying to bump it up in August air... )

The fact that it all worked out in the end does say that, overall, the car wanted the taller gear (and yes, a 5 speed trans with a lower than what we have first gear would be nice too)....

We will see how it all works out again this year.....

[tortoise]

NHRA shortend the track to 1000' from 1320' to keep the speeds down for the top fuel cars.

    

With the amount of wing they run, the fuelers hit the aero wall at about 1000 feet. Little or no effect on top speed. They do get 320 feet of extra shut down distance.

[wobblywalrus]

This goes back to the original question about power curves.

The dotted curve is for a pretty much standard engine that originally had a torque curve shaped like the one at the top with 50 lbs-ft torque, maximum.  Intake and exhaust tuning with some spark advance curve tweaking was used to take away some of the torque from  the left side of the hump and move it towards the right side.  The dip in the torque curve around 5,200 rpm shows where I removed it.

The engine before the intake, exhaust, and advance changes pulled hard up to 6,500 rpm and then it started to go flat.  The motor was sorta flat until around 6,000 rpm and then it pulled hard until about 7,500 rpm after the changes.  It was was much faster and a lot of fun to ride.  I just had to make a quick shift around 6,500 rpm to make it work.

The solid line is the torque curve for the 865 cc engine.  I have done the spark advance curve and intake tuning.  The exhaust tuning will be done this week and the dyno session is scheduled for the 14th.  Just like with the little 790 cc motor, I am trying to bias the torque curve toward higher rpm.  The curve I am trying to get will be good for LSR and lousy for everything else.

Do not abandon your long block until you have done this sort of tuning.