drag racer looking for knowledge from the pullers

T

Todd W

Comp Diesel Sponsor
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Nov 18, 2006
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I am a dragracer who races a 12v. I did not grow up around diesels and have been learning by failure mostly for around 7 or so years.

I believe that the most powerful diesels in drag racing come from sled pulling technology, like hypermax, sheid rail, John robinsons funny car, Seth Sullivans Maroon truck and so on.

There are others having success at going fast but when the 12v sledpuller guys line up it sure seems there engines are on a different level than the rest.

I know there is a lot of information that is not going to be given, but I hope to gain a little bit of info that is probably well known and no longer secret.

My first question is about the beginning of a pull. I have been watching a lot of pulling vids and wonder about the process of getting ready to launch, go, let er rip, or whatever term you guys use to describe the first movement of the pull.

This is a video of rock hard ram
[ame="http://www.youtube.com/watch?v=B6euCBnBWLE"]2011 SPRINGFIELD, OH COTPC, RWYB VAN HAISLEY, ROCK HARD RAM, 1ST PLACE - YouTube[/ame]

This seems fairly typical of the start. the white smoke is billowing while the rpms slowly rise. and they rise in a way that sounds like the engine is missing or something. Then all of the sudden it becomes smooth and sounds awesome and away she goes.

What is happening that a guy can't just give it throttle and build the rpms fast?

what happens when you just blip the throttle? does it miss or does it rev up nice at all?

what causes it to suddenly clear up and sound sweet? Is it just applying load? would it sound sweet and clean if load was applied at a lower rpm?

My questions are related to a drag launch. I run an auto and will launch at way less rpm than a puller does. would a puller engine setup work at all in this case? what changes would be benificial to a drag racer?

I realize that rock hard ram is in no way similar to my drag truck but i feel that learning about some of the way you guys do things might be of benefit to me. thanks
 
Most sledpulling rules allow the puller 3 minutes to get off the line, which obviously isn't going to work for a competitive drag vehicle (unless you're racing against someone with a very similar setup to you).

The smoke and behavior you see is due to fixed injection timing, the action of the governor on the pump, low compression ratio, and the timing of the start of water injection. That, and they're spooling rather large turbo systems, from huge singles to triples. All that takes a relatively long time to get wound up. These engines are optimized to run at WOT and not much else, and the clutch setups let them do that. There are no autos at the top of the food chain in sledpulling.

It'll be a lengthy thread to 'splain all of it, maybe Team 12V will chime in for the long list...
 
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For the most part the long delayed start up is due to the Agricultural style governor in the injection pump as opposed to the autmotive governor. The ag governor throttles are very stiff and hard to move at the start, but they compensate in the rack for RPM changes MUCH quicker than the auto governor.

At least this is my understanding. Haha.
 
NTPA, PPL, and all the other top HP 4wd classes don't run auto's usually. If they did it would be too much of a hp loss to the wheels and no garantee of them holding up for more than a few passes. Most i've seen are set up with Glide clutches and reversers ran thru a drop box. Pretty much the same as the 3.0 and super stock diesel classes with a little bit different clutch setup.

I know what you mean with the blown alky trucks runnign 400's tho. Our Super Mod 4wd class with KTPA are setup the same way, but i honestly don't enjoy the class much. They make no RPM and the ground speed is pretty low. Every now and then a few NTPA prostock trucks will run with them and put alot of footage on them.
 
kino_fab said:
NTPA, PPL, and all the other top HP 4wd classes don't run auto's usually. If they did it would be too much of a hp loss to the wheels and no garantee of them holding up for more than a few passes. Most i've seen are set up with Glide clutches and reversers ran thru a drop box. Pretty much the same as the 3.0 and super stock diesel classes with a little bit different clutch setup.

I know what you mean with the blown alky trucks runnign 400's tho. Our Super Mod 4wd class with KTPA are setup the same way, but i honestly don't enjoy the class much. They make no RPM and the ground speed is pretty low. Every now and then a few NTPA prostock trucks will run with them and put alot of footage on them.
Click to expand...

Yes the NTPA/Grand National 4x4 mods run mostly a clutch setup forsure. Puzzles me as to why and how the blower trucks make out well with the setup? The OSTPA class that runs against Shane, Erik and the other diesel mods seem to compete pretty good if not better at times than the diesels and have both wheel speed and power to boot!
 
one of my good friends run a smfwd with the ostpa its black diamond .he has run a clutch and a auto and he has better luck hooking it up with the 400.
 
Up N Smoke said:
one of my good friends run a smfwd with the ostpa its black diamond .he has run a clutch and a auto and he has better luck hooking it up with the 400.
Click to expand...

I have heard the same a bunch of times but never hear the reasoning for it...any ideas why he says this?
 
after thinking about it, i guess one reason why our SM4wd class isn't as impressive as what you would one would expect is the rules only allow a 8-71 blower with 53% max over drive. Most only make around 6500-7000RPM usually unlike the 2wd trucks that turn around 9000+rpm. The automatics really take some hp away from them too. Here is a video

[ame="http://www.youtube.com/watch?v=1x4C9RPVZ7M"]Super Modified Four Wheel Drive Trucks at Russell Springs, KY (6/7/13) - YouTube[/ame]
 
strange, our SM4WD class that allows 500cu blowers (8-71's with only a max of 40% overdrive) 620cu N/A or now diesels/3.2" charger seem to have quite a bit more power and wheel speed than those. Wonder if it has something to do with the long wheel base they are running. Our class runs basically the NTPA Grand National rules with the blowers mixed into the class.

Ryan
 
kino_fab said:
after thinking about it, i guess one reason why our SM4wd class isn't as impressive as what you would one would expect is the rules only allow a 8-71 blower with 53% max over drive. Most only make around 6500-7000RPM usually unlike the 2wd trucks that turn around 9000+rpm. The automatics really take some hp away from them too. Here is a video

Super Modified Four Wheel Drive Trucks at Russell Springs, KY (6/7/13) - YouTube
Click to expand...

After watching this video, I got to wondering. How come more diesel guys don't run the old bodies or rat rods like that?




Also anyone know of a good gas pulling forum I can check out for pictures?
 
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