Competition The Ultimate Diesel Drag Racing Engine

[COMP461]

THE ULTIMATE DIESEL DRAG RACING ENGINE



This thread is going about what most thinK it would take to build a diesel drag racing engine. This is not a street engine, but a Pro engine in either a dragster of chassis type racer, and even including a Pro Street entry. I will give out information as I see it is necessary, I am sure Bill Fletcher and Scott Benz will participate also. This is not going to be a bashing session, and if it becomes one, I will go back to work on my own engine and not give out the hard found information I have gained in the pursuit of becoming Diesels quickest Truck.

Whether any one agrees the standards in drag racing has been set , the players are well known , it has become apparent that what worked in sled pulling , or dyno entries , is not what is fast in a all out drag race venue .





Here are my first thoughts, in order of importance.

1. AIR FLOW

2. VALVE TRAIN CONTROL

3. CONTROL OF FUEL CURVE

4. RECIPROCATING WEIGHT

5. BLOCK INTEGRITY.

 

[Sled Puller]

Simple, absolute max power in a Cummins 5. 9, call Scheid Diesel, end of story.

 

[COMP461]

AND WE ARE TO BE IMPRESSED WITH THEIR DRAG RACING ACCOMPLISHMENTS HOW.



The drag racing engine is very different from a sled pulling engine, it must REV-GAIN, and not spit fluids and such all over the place. To REV-GAIN it will have to run close to a good fuel curve. This takes away the thick smoke; another aspect is in the real drag racing world, you only have 7 seconds to complete staging, and a second or two before the tree drops. No setting at the line and spooling for 15 to 30 seconds

.

 

[COMP461]

What was involved was my new piston and rod combination . I haven't run this new engine yet , the parts are made , and have been trial fitted , but I am out of time before Indy or the race up in the north west , which ever I decide is best to go to I have had to go back to track testing , and have had to forgo the engine development for a month or so.





The new motor is going to be much lighter , both in reciprocal weight and in total weight. The key to all this was the new Aries Piston , which will be available to any one wanting one , the catch is this piston requires a custom rod . the only part of the piston that will remain under wraps is the design of the dome / chamber , you have to provide that your self . I have the crank back from the grinder , and its 97 lbs . down from 125 stock

 

[John_P]

Greg:



Great idea on a thread of this type even if Gene doesn't think so! :-laf



I don't have a drag race truck like yours or some of the others on this site, but did recently have Scheid Diesel build the engine for my 1996 Dodge CTD which I went "all out" on. One mistake I made was using the old 12 valve block with over 220,000 miles on it. Recently, it developed "pin hole" leaks between cylinder #3 and the inside cooling cavity. Kent just got done putting in a brand new block in for me which I should have done from the beginning. But the old 12 valve block didn't even have to be bored upon rebuild so that is why I didn't do it. Looking back on it though, all the engine "heat cycles" and stresses of hard use including the "hot tanking" of those blocks when they are rebuilt I guess was a little too much for the old block. So,... ... . if you do plan on a rebuild of an older higher mileage 12 valve engine start fresh with a new block! That will defintiely insure "block integrity" as you point out.



Anyway, as many of the members here know, I had Scheid Diesel install their Arias Pistons in my engine. I think for a drag race engine they are a great way to go. When my 12 valve bock was taken apart by Kent, Brandon and Chris at Lafayette I had a little over 10,000 miles on the pistons. Upon inspection they looked excellent! Other than being carboned up on top some, the sides etc. looked like they had just come out of the box! I also think that the 14mm studs top and bottom are a must with the "firering" system that Scheid uses along with a girdled block, and possibly heavier rods (which I did not do) is a good choice. You mentioned the weight difference of the Arias Pistons vs. stock and I also saw that too by personally weighing them! My new Arias Pistons weighed about 1168 grams vs. 1325 for the stocker 12 valve piston. Regardless of how you look at it that is defintiely weight saved in the rotating mass. Of course the cylinder head needs work in proper porting, heavier springs (I went with the 60lb. )

on the intake and exhaust, and a P7100 pump with a good fuel flow setting and the right internal parts. I put in Scheids' Mild "Street" Cam, but for a drag race vehicle a "hotter" unit is going to be needed.



Hope this helps some.



--------

John_P

 

[COMP461]

I have always liked a seasoned block for a maximum effort drag racing power plant . in the old days in the gas motors you started with a truck block with miles on it . the repeated heat cycles assumed a stable block. Now that all drag racing engines start as a purpose built block , such as the DRCE III you must start with a virgin block. And no Fletch you cant have it. These blocks are high nickel , coincidently the same as a Cummins block. In fact the Chevy and Dodge Pro Stock blocks are cast by one of the diesel block manufactures , but I don’t remember if it was Case or Cummins , but we had to learn all over about honing .



Now we come to a big part of the whole equation , RING SEAL . It dose little good to have every thing on kill and have a great portion of you initial push leak past the rings as blow by . the reason for the new pistons was a better ring package and ring placement. I believe that there is a great deal of power being blown by the rings in most diesel racing applications . the cure is bore stability , and ring stability. We can look to Our gas brethren to find some of the answers . On a maximum effort engine the Pro’s will spend a great deal on bore finish , even to the extremes of using Nicaseal sleeves ,at $10,000 a set . I don’t believe we are to that point yet , but the we should work the bore seal out as far as we can . I have built a honing plate out of 7075 aluminum , and have engineered out the right thickness to achieve the same distortion in the block as the head . the difference will open your eyes to the effectiveness of this process .



The piston I am using weighs in at 825 grams and the rod is a little over a 1000 , this is a reduction of almost 2100 grams when you use a lite wrist pin. This is 4 pounds of ugly weight swinging any way you look at it. Will this reduce reliability. Yes and no , what do you conceder reliability in a racing engine. When you reduce weight of reciprocation parts you reduce stress on the whole bottom end , crank , mains and all. I look at reliability as will it last the life of the rings with out breaking or giving up performance.

In my comp motors the rings were good for about 60 to 70 passes before they started to give a bad lead down , some where over 10 to 15 % that was the life of the rods also. My diesel leaks down is some what great with stock parts , spiking of this how many of you have a leak down tester.

 

[Sled Puller]

AND WE ARE TO BE IMPRESSED WITH THEIR DRAG RACING ACCOMPLISHMENTS HOW.





.

So who started the bashing? Nice Greg, you are a true sportsman.



RacinDooly,

http://www.scheiddieselmotorsports.com/ScheiddieselMotorsports/index.htm

 

[COMP461]

If I was starting over in a diesel. It would also be a Duramax . this little motor would be king of the hill in a chassis truck or dragster. And the neat part of a Duramax is it could easily turn 7500 + RPM ,I believe

 

[DieselTweaker]

first off WOW this is going to be a very interesting thread with a lot of good info.



what about using gas porting the pistons for ring sealing?



Also props on the rotating assy. that's a bunch of weight to take out,,, And will rev very fast and high, I know most of the time you can figure a tenth of a second for every 10 pounds of rotating weight, and a tenth for every 100 pounds of static weight.

 

[COMP461]

might try the side gas ports, like the old superstockers ,



I I have also been looking at running more vacuum then I currently do .

 

[DieselTweaker]

what are you running for an evac. system now?

 

[COMP461]

I had been using a old smog pump off my comp car , but found that the intake side of the turbo in the air cleaner will make a few inches

 

[COMP461]

That kind of details are a little bit to much to tell at this time , the pistons are custom order type , so no part number to speak of just give them the specs and dish design , ring placement and type . Anyway my dish is something a little different , designed for the RPM and timing I run and probably to specialized for most applications



My crank is knife edged , with the counter weights profiled , and the rod throes hollowed. The rod journals have been cut down to a smaller size also . rods are done by the same people that did me so well in comp.

 

[bgilbert]

That kind of details are a little bit to much to tell at this time , the pistons are custom order type , so no part number to speak of just give them the specs and dish design , ring placement and type . Anyway my dish is something a little different , designed for the RPM and timing I run and probably to specialized for most applications

Sounds no different than what Scheid will do for ya. http://www.scheiddiesel.com/trkpull.htm

 

[COMP461]

I'm not trying to sell anything, their pistons were not what I needed, so I went to the place they get them... and the whole deal retailed at about $250 a piston with rings and wrist pin each, I'm not used to paying retail, but that gives you a Ideal why.

 

[DieselTweaker]

the pistons are custom order type , so no part number to speak of just give them the specs and dish design , ring placement and type



The rod journals have been cut down to a smaller size also .

now, there wouldnt be a diffrent pin height in there too???? :-laf



hrmmmm..... STROKER Oo.

 

[Hohn]

my take on racing a diesel

Well, I don't think a CTD is really even close to optimized for drag racing. Setting up for racing is tantamount to completely re-engineering the engine.



First, the pistons are WAY to heavy. The compression height is way too tall, which helps stability (and keeps the bores lasting seemingly forever), but REALLY hurts performance.



So, first order of business is a superlight custom piston. Compression height < 2". Ultralight tool steel pins, . 990 BB Chevy size. Piston dome is proprietary high-swirl dome designed to enhance speed of combustion.



Pistons are hung on custom Aluminum rods that are much longer than stock. AL is used for harmonic absorption and weight reduction. Rod/stroke ratio is 1. 75, no more, no less. Failure analysis determines the smallest rod journal that can be run. This reduces bearing speed (and friction losses) while cutting weight.



Crank should be rifle-drilled, bullnosed, and knife edged. All nonessential weight is removed. Reducing reciprocating mass reduced the crank loads, allowing more weight to be saved. Crank is 4340 or ???. Should be DEstroked to enhance RPM capability, though this is less important if the rod ratio is the proper 1. 75.



Block-- custom beefed up unit cast in Aluminum. Think Indy MAXX or KB Stage ten and you get the idea.



Compression: 13 or 14:1 Something lower than you may expect. It should be just high enough to start in 70something degree weather w/ no ether. Final ratio doesn't matter much. It's all in the package.





Head: This is HUGE-- by FAR the most important, as Comp correctly (imo) mentioned. What's needed is a custom head with MUCH longer valves. The port windows are simply to small with short valves. With titanium intake valves, they can be lightweight even if they are 1" longer than stock. That's a HUGE increase. The head can now have large ports (which are a luxury the turbodiesel gives you, as intake velocity at low RPM doesn't kill die like it would on a gasser with oversized heads). With the large ports, they should be raised as high as possible, reducing the "turn" that air must make on its way in and out of the cylinder. Exhaust ports should be very short, reducing heat lost to the head and enhancing turbo response.



Cam should be a custom 8620 piece with Schubeck-style sintered ceramic tappets. Beehive springs allow higher revs with lower seat loads. Cam should have less overlap that a gasser cam, as the NA gasser depends heavily on "exhaust pull" breathing, effectively acting like a "5-stroke" engine. A turbodiesel needs to reduce inert gases leftover, and fight reversion. Thus, we want a really WIDE lobe separation (117 degrees or more, imho). Maybe our custom head could be setup for DOHC?



Anyway, that's just a start, but it's a step in the right direction, I think.



JLH

 

[TxDieselKid]

Greg,



Did running a shorter rod ever cross your mind in your research?

 

[COMP461]

Wow Have you been hiding in my shop . Justin you are very close. And de stroke is the a good guess. Along with a smaller rod journal.



If you understand rod /stroke ratio , then you understand why also. This is the direction I am heading .



14 millimeter studs are not necessary , and might even hurt , some of the Pro Stockers run 3/8 head studs to let the head float a little. What we have thought in the past to be blown head gaskets , by oil in the water is not a loss of combustion containment , but a lack of gasket crush around water and oil. The . 043 O-ring is more then enough anyway , the fire rings are just a crutch and a waste of time ,if you cant hold it in a drag racing diesel with this ,you are running the motor wrong.



The are several other ways to contain combustion , and those are available ,but most are secret , and F1 or Indy car type seals . The fire ring is nothing more an attempt at solving a tuning problem. And is only a little , If any better then a O-Ring .



The diesel doesn’t rev enough to need Titanium valves in a 24 valve , the reason for a longer valve would be to gain installed height, thereby allowing a spring in that will cover more lift . the springs available are a little pricey, but necessary to cover the . 600 lift needed. If the rocker arm system gets finished you can grind a cam , with around . 375 lobe lift and get there from here. The Schubeck lifter would be my pick over a roller any day , the roller is another unneeded item, . with the big cam core , at 55 mm and only . . 375 lobe lift, you have a beefy enough base to control the lifter with the large mushroom lifters we now use .



Justin you are in the ball park,

 

[Sled Puller]

Once again, you guys are trying to turn a Diesel into a gas engine. GM tried a version of that once, a 5. 7 and a 6. 2. They were stones.



Use the advantages that the Diesel has, long stroke and torque, gear it right, and go from there.



You could possibly lighten it up some, because you are not looking for million mile longevity, but to take the Diesel characteristics away from it, you will be stepping backwards.



The Cummins 5. 9 has already been pushed well over 1200 HP,reliably, with a stock head. It also has enough torque, to virtually not lose RPM when you shift.

I don't feel you need this gasser "rev gain". Light the chargers, mash it, shift,shift,shift. Race over.

Turning it into a gasser to make up for not understanding how to use Diesel torque to your advantage, is ridiculous.