So, what is it that makes an engine accelerate?

[cstraub]

Bear your "Dead On". Case in point with circle track, I'll will ask them if they can flat foot it around the track and 99% of the time they can't. So I tell them to get with their chassis guy and when they can, then the engine can be looked at.

[Gearhead]

I'll pitch in and say Bear & Chris are right on! As Bear relates the total package - Engine through drivetrain - Example: Comp Eliminator powerglide transmission... lightened planetary, roller bearings, not to mention the plethora of torque converter designs, etc. Rear end - lightened ring gears, rifle drilled axles - use of lower drag housings such as the 12 bolt Chevy drop in for a 9" Ford Case. The 9" drop in case is strong and easy to change gear ratios and service by easy removal, but the 12 bolt has a higher efficiency due to the intersection point of the pinion with the ring gear... so aftermarkets came up with the 12 bolt gear set in a pumpkin to drop in a 9 bolt housing.
Hmm... now how does that relate to my jet?
P.S. - Chris, I had a dirt track customer last year that his primary goals was not that of peak power. He desired a decent base tuneup, but then wanted to know the effects of timing changes on power output and restrictor spacers on power output so that he had a correlation of where to go when he needed to vary the power for track conditions..... ie... flat foot it and drive!

[MikeF]

Traction!
Just wanted to repost #9 on the list.
You can have all the HP in the world, but if you can't get it to the water/ground, it won't accellerate the quickest/fastest. :crossx:
Examples:
Hicks/Hottub, 5?? c.i., 6500+/-RPM, MPD pump, runs 7.50+/- in the 1/4 mile at nearly 140 mph.
JBG/BlingBling, 45? c.i., 9700+/-RPM, prop speed 11K+ w/ Grose CNC prop, runs 7.50+/- 1/4 mile, 140+ mph.
Two of the quickest (N/A) boats in the NJBA!

A little off topic, but relevent none the less!

[cstraub]

I'll pitch in and say Bear & Chris are right on! As Bear relates the total package - Engine through drivetrain - Example: Comp Eliminator powerglide transmission... lightened planetary, roller bearings, not to mention the plethora of torque converter designs, etc. Rear end - lightened ring gears, rifle drilled axles - use of lower drag housings such as the 12 bolt Chevy drop in for a 9" Ford Case. The 9" drop in case is strong and easy to change gear ratios and service by easy removal, but the 12 bolt has a higher efficiency due to the intersection point of the pinion with the ring gear... so aftermarkets came up with the 12 bolt gear set in a pumpkin to drop in a 9 bolt housing.
Hmm... now how does that relate to my jet?
P.S. - Chris, I had a dirt track customer last year that his primary goals was not that of peak power. He desired a decent base tuneup, but then wanted to know the effects of timing changes on power output and restrictor spacers on power output so that he had a correlation of where to go when he needed to vary the power for track conditions..... ie... flat foot it and drive!
Gear,
Set Goal. . .build combination. . .excute. . .. achievement. It's pretty simple but I see all to many times guys get caught up in the status quo and want to belong that they end up building a combination that is someone elses path of reaching their goal.
Right now on another board a guy is wanting to get suggestions for an engine for a 3200Lb car, 4 speed, that is limited to an 8" tire. He has a 454 block. The majority wants to put a 4.250" stroke in it and punch it to 4.310". I say put a 3.766" stroke in it and punch it to 4.350". Spinning tires off the line doesn't win races. My way of thinking is launch easy and role into the throttle, but hell I don't have race car so I don't know anything.
Okay back to acceleration. . . .

[cstraub]

Just wanted to repost #9 on the list.
You can have all the HP in the world, but if you can't get it to the water/ground, it won't accellerate the quickest/fastest. :crossx:
Examples:
Hicks/Hottub, 5?? c.i., 6500+/-RPM, MPD pump, runs 7.50+/- in the 1/4 mile at nearly 140 mph.
JBG/BlingBling, 45? c.i., 9700+/-RPM, prop speed 11K+ w/ Grose CNC prop, runs 7.50+/- 1/4 mile, 140+ mph.
Two of the quickest (N/A) boats in the NJBA!

A little off topic, but relevent none the less!
No Mike your on topic. Can you hook it? What good is a 800HP big block if you can't put to the water. . .dirt.. .or asphalt. It's no good, because the guy with 500HP is going to pass you because he has it all working for him.

[cstraub]

Remind me once we get into the heads and induction to talk about Ram Effect, I was just reminded I said I would do this on another thread and didn't.

[Gearhead]

Gear,
Right now on another board a guy is wanting to get suggestions for an engine for a 3200Lb car, 4 speed, that is limited to an 8" tire. He has a 454 block. The majority wants to put a 4.250" stroke in it and punch it to 4.310". I say put a 3.766" stroke in it and punch it to 4.350". Spinning tires off the line doesn't win races. My way of thinking is launch easy and role into the throttle, but hell I don't have race car so I don't know anything.
Okay back to acceration. . . .
Chris,
I like the way you think.... Lots of lower RPM torque in a stick car and an 8" tire!!! Unless he has one heck of a chassis he will enjoy a lot of white smoke from the tires! The 4.25 would be good for the jetboat but in my opinion not too good for the limited tire car.
Now your alternate idea holds merit. Comp Eliminator A/ED .... 440" to 460" range... using 4.5 to 4.6 or larger bores... 3.4 to 3.6 strokes... 12" to 14" tires sub seven seconds... With the short stroke the engines don't have monstrous torque down low, but they sure do RPM and make HP down track!
Gearhead

[cstraub]

From combo meals to houses we just are taught bigger is better while in reality we need to worry about what we need things in moderation. I'm not the most religous person but I believe in moderation.

[UBFJ #454]

"Hmm... now how does that relate to my jet?"
Hmmm ..... Now that's a subject worth its own Thread that could also be very interesting. Gearhead, why don't you start a thread to discuss that topic in the 'Jet Section'?

[steelcomp]

"Hmm... now how does that relate to my jet?"
Hmmm ..... Now that's a subject worth its own Thread that could also be very interesting. Gearhead, why don't you start a thread to discuss that topic in the 'Jet Section'?
Bear, you can bet every bit of it applys to your jet, in one way or another. The point is, as you posted earlier, there's no one thing that makes an engine better or worse...it's alwyas the best combination. The trick is in learning as much as possible about each componant, knowing how they effect eachother, and how to combine their qualities (or avoid their flaws) to achieve your goal. Obviously, the higher the goal, the more you have to know...or pay someone who does!
Chris and Steven. Are you having fun?
Smart guys. LOL!
OK...where I'd like to start, is in the combustion chamber. In a four stroke engine, there's only one power stroke, and like someone posted on another site, the other three strokes are just hindering it. Flow as much as you want, lighten everything you can, cam it, ram it, slam it, but unless you know what's going on and how to optimize the burn, it's all just spinning metal, creating nothing.
What goes on in the chamber? Why does gasoline detonate? How have chambers evolved to maximize burn? Can we talk about things like compression ratio, swirl, tumble, quench, etc? To me, this is the heart of the matter, and where the power is made...or not.