I got the Diesel crank

[Guest JAMIE T]

I got the diesel crank from the pick and pull. it was a tough job at the JY. I didn't get the short block. I probably wont ever do a 3.0L, but I figured it would be nice to have, and maybe I could help someone out that can't find one.

[opie]

You have mail my freind. Doug.

[Guest Anonymous]

I pulled one a couple years ago in a JY, (sold it long ago, sorry.) Lucked out and came across an L28D sitting on the ground already pulled from the car and turned an hour and 40 bucks into $250, if nothing else pull em and sell em it's worth the time as long as it's easy to get to the crank in a timely manner.

 

I swear it took 2 weeks to get the black oil stains off my hands from all the soot in the diesel engine's oil. You run into that problem too Jaime? I think for that reason alone I'd never want to be a diesel mechanic, that oil is just foul stuff.

[opie]

They don't sell as well anymore, because the mystique is gone. It's a lot of trouble to do a stroker.

[Dan Baldwin]

It's not a lot of trouble to build a stroker. Not all that much more than a generic rebuild. Pretty well worth it, I'd say. I believe the cranks still go for $250, and get sold pretty quickly. Mystique? Anybody that mods for that reason is an idiot (not saying there aren't any about). That's whay 3x2 carbs were the LAST thing I did to my motor, not the first.

[opie]

I guess thats another offer to buy the crank then. I guess I was wrong. You know, I think it was an impulse reaction, but I don't think I really need it now. Gee, I sold a diesel crank for $200 earlier this year and it took 4 months of posting to sell at that price. I just thought I'd replace it now. Four months didn't seem very quick to me. I only had 2-3 people even email me about it in that time. The guy who did buy it had lost his desire for a stroker and was just reselling it in a completed engine kit with forged pistons to fund another option.

 

"Mystique" is a very powerful sales tool in the world of image. It motivated millions of people to pay $80-$150 or more for sunglasses, court shoes. I wouldn't want to make that many people angry all at once.

[Tim240z]

Well all this talk about strokers and V6 conversions (see other post) has me thinking about doing something with my 2.4 Z daily driver when the V8 is done.

Maybe you guys can give some thoughts/opinions on:

L6 stroker in the 240 or,

3.8 V6 chev or,

2.8 L6 Turbo or,

if this is feasible L6 stroker turbo?

 

This will be a bare bones conversion (nothing like the current LT1 project), and since this will be a daily driver, reliability and fuel economy will be important. Just looking for something more than the lazy @$$ 2.4 L6 that I am currently running.

 

Thanks,

Tim

[opie]

Don't overlook destroking, too. Short stroke larger bore configurations spin up fast, generate a lot of torque. Didn't James use a destroked motor in his 240Z?

 

Ford destroked the 2.3L motor in the 80s to about 2.1L and developed 600hp with all the other magic they do to race motors. The 69 Z28 was a short stroke, large bore 302ci.

 

On the other hand, there's a 427ci motor out there that sounds really cool like a side oiler Ford type of thing, but it actually was used in garbage trucks, etc and had a long stroke that was useless to performance apps.

 

I guess it depends on your intended use.

[Dan Baldwin]

I believe destroking as a performance enhancer is a myth. Haven't run the numbers for a SBC, but for the L6, no destroked combination offers enough additional revs to make up for the lost displacement. Rev limit varies roughly with the square root of stroke, so decreasing stroke 10% only gets you on the order of 5.4% higher redline, and you've lost ~10% of your torque everywhere else. Improved rod length to stroke ratio does get you a smidge more revs than the square root of stroke ratio would imply, but not much.

 

The following combinations give the same max piston acceleration (lemme know if anyone wants to see the tedious derivation of the eqns of piston motion)

L28 at 7000 rpm (rodlength/stroke = 1.65)

L24 at 7320 rpm (rl/s = 1.80)

3098cc L31 at 6810 rpm (rl/s = 1.60)

2569cc destroked L28 at 7320 rpm (rl/s = 1.80)

 

Note that the destroked L28 has the same peak piston acceleration at 7.5% higher rpm than the L31, but has 17% less displacement. Destroked L28 => 11% less potential power + 17% less potential torque = losing proposition. That doesn't even account for the KA24 pistons being somewhat sturdier at high revs than the L28 pistons Norm keeps busting. My 240SX (KA24DE engine) redlines at 6900 rpm with a 96mm stroke. In a 83mm stroke 3.1 liter, equivalent piston acceleration is reached at ~7360rpm! I've revved my L31 to 7000 (with excursions to ~7800) at ~35 track days over the past 7 years, no problems.

 

Destroking for performance ONLY makes sense if you're displacement limited, in which case you'd want as large a bore and as short a stroke as burn rate/distance for flame front to travel will let you get away with. Of course you'd want your engine to be right at the displacement limit, if you run out of bore potential, you add stroke regardless of what F1 bore/stroke ratios are.

 

If you're not displacement-limited by class rules, stroking makes perfect sense, and destroking would cost you torque and power.

 

I've said this before and I'll say it again: The only quick-revving contest a destroked L28 would win vs an L31 is one where they're turned by a hand crank. Under any load whatsoever (dyno drum, 1/4 mile, roadracing) the stroker will rev up more quickly.

[pparaska]

I agree with Dan 100%.

 

Destroking to be able to rev higher is MAYBE nice for a race situation, but if you are driving on the street, I think you're giving up performance. It could also be used to fix a problem like reliability or durability on a vert low rod/stroke ratio configuration.

 

My reading info on rod/stroke ratios tells me none of it really matters below 6000 rpm, as long as the piston isn't rocking like crazy with a short ring package, and the ratio isn't horribly low (< 1.4 or so). The advantage of higher rod/stroke ratio may be in detonation resistance though.

 

Torque is King on the street, IMO, or more correctly, more torque from 1500-5500 on the street will get you the kick in the back that's satisfying ALL THE TIME. The old timers I talk to say the high revving motor like the Z/28 302 was a BITCH to drive around town. Sure it had alot of peak power, but it didn't come in until the 4K+ band. Ever drive something like that on the street? It sucks IMO.

 

All my opinions of course.

[opie]

Just like my destroked post, "I guess it depends on your intended use", but not 'all things being equal'.

 

Your Pontiac situation is an obvious intended use issue. Really a different forum here, but there's a not so little amount of arguement on the rear gears your Poncho buddy is running. The 455 is a torque monster already. You will never get a decisive answer, only opinion on this, but I think the 3.55 gear would work better with his 455. I plan on using the 1.65 rockers, 3.55 on a 462ci in my gto. The rest of the setup sounds reasonable, without knowing what cam he is running, weight and assuming a tire height, of course. Seems he could have gotten into the 12s with the old setup (assuming weight, blah, blah).

 

I've only played with the 2.3/2.1 Ford and sbc ratios, so I can't extrapolate on the L6 without doing the bore/stroke possiblities for myself, but I'll vote for "the glass is half full."

[Lockjaw]

The poncho guy ran the crane 284H I think. It is a good sized stick. He did not add enough compression either, he probably ended up around 9 to 1. He was talking about getting more stall, and I was like, you are an idiot. You don't need stall when you have an engine set up to breathe that is all choked down. What you need to do is retard the cam shaft, get some big tube headers and turn the thing tighter. It is a big block,it has torque already.

 

I read an article in hot rod where the built a 350 using the rods out of a 6 cylinder inline ford, and it made alot of power on 87 octane gas, and their claim was that the longer rod improved the rod to stroke ratio and made the engine more detonation resistant and powerful. I think their original claim was Chevy screwed up when they raised the displacement of the 327 to 350 with stroke rather than bore. You know how that goes though, some people just think the 327 was "the smallblock". Is that the one you were referring too?

 

I am sure you are right about the stroker engines as well. I started with a 2.4, went to a 2.6, and then a 2.8, and performance improved with displacement. Substantially. I am sure a 3.1 would really put down the power, and may work towards that one day.

 

I am wondering if on the shorter rod engine if offsetting the piston pin a little would help?? I know JWT does that in their forged pistons they stick in the 300ZXTT's since it makes them alot quieter. I think the HP loss was less than a hp a hole. I mean if it improved durability, and you picked up some power from the increased leverage, and lost a minimal amount at the expense of extra reliability, but remain positive in the gain. Hummm.....?

[Dan Baldwin]

The article I'm referring to was WAY back in the 80s. Some SBC guru who'd gone through a bunch of iterations decided on 5.7" in favor of 6.0" rods. Then again I don't really recall exactly how scientific it was. Purely anecdotal. Offset piston pins could allow for greater leverage on the crank during the power stroke. I believe some I-4 motorcycle engines have offset cranks underneath the cylinder bores for the same effect, but keeping the pistons symmetrical. Seems like an idea that has some potential. I always thought the biggest advantage of increasing the rod length/stroke ratio was reduced peak piston acceleration on top at a given rpm (increased rev potential). Longer rods would tend to increase the "dwell" time around TDC, while shorter rods would reduce it. Should the piston taking more time to whip through TDC improve detonation resistance? Interesting. I only run 93 octane pump gas (10.8:1 CR). Don't think I wanna have the car rely on race fuel, but don't mind paying extra over 87 octane. Kinda stuck with the rodlength/stroke ratio I've got, but it seems to be working fine:)

 

Going WAY back up to Tim240Z's post, I'd prefer the stroker L6 turbo option. Might try that someday myself!

[Dan Baldwin]

Oops, I meant to say (regarding the old HotRod SBC article) "he decided in favor of 5.7" rods over 6" rods".

[Guest JAMIE T]

I too have seen them sell for $250.

LOL, that black oil is on my elbows, on my legs, just about everywhere. It was a PITA to do this a the JY. The car was complete, so, no one had come along and pulled the motor for me .

As for anyone interested in buying it, I would have to get atleast $225 for it to make it worth it. I did the hard part, I even powerwashed it. I was surprised to see how nice the forging is. You don't see that sort of quality in Domestic(production)forged cranks. Honestly, I had my hands on a Sonny Bryant stroker crank for a 347 ford, and it wasn't as nice as this crank.

As for this discussion on strokers, and destroking. I've seen and done some of both. I'm a torque guy. I used to own a low 11sec. '70 Olds 442 W-30. 468 cubes of Big Olds torque. I also had a hand in a 377 de-stroked 400 SBC. The motor was put in a pro drag '55 chevy(full tubs and lexan, fiberglass, etc...). That car would run 10.10's real consistantly all motor. The next season the guy redid the motor using a STOCK 400 crank, re-using everything else(he also re-used the rods, but got new pistons with the same compression). The car then ran consistant 9.80s. Torque is alo usefull in roadracing, as it lets you pull out of turns harder. FWIW, RPM is what kills engines. More cubes = more power at usefull rpm ranges. I agree with Dan and Pete above. My old engine machinist runs Comp Eliminator in NHRA Pro Drag racing. He uses engines ranging from 265ci to 290ci SBC's in his car depending on the competition and weight of the car. He uses the small cube motors because it allows him to run a light car per CLASS RULES. He makes over 750 hp with these small cube motors. But the engines turn 10K rpm and only have to do it a couple of times per weekend. The engines also get a re-ringed, and new valve springs after each event. He's alittle secretive about his combos, but I know he uses 14 degree heads and two 660 Holleys on a sheet metal tunnel ram. His cams are also approaching 1" lift . One funny thing is all of his cranks are destroked 283 cranks. He's my old machinist because he moved his shop a little to far away for me. We've had many discussions about bore, stroke, and benefits of stroking and destroking. He KNOWS what makes power and alway recommends cubes over RPM. Like I said above, he uses small cube motors for CLASS RULES. Thats my rambling.

[Guest JAMIE T]

BTW, the reason I got this crank in the first place, was because the thoughts of a huge turbo atop the stroker appeals to me. WANGON MIDNIGHT

[Guest Anonymous]

You fellows will have to get off those city streets and stop lights onto some two lane black tops with open road ahead and open road behind in the hills and valley vistas to apreciate going into a 45mph corner at 85mph at the throttle of a possibly destroked v8 motor with the right hand on the steering wheel and the left arm resting on the door sill of a Z sports car doing a 100 mile cruise in the middle of nowhere. That is my dream not bumping thru traffic lights going to a dragstrip .

[Lockjaw]

I am going to be devils advocate a little. First, destroking an L6 would not be that big a deal if you were force inducted. I have toyed with the idea of building an engine with a 2.4 crank and rods, and a 2.8 liter block bored to 89mm. That would put me back at about a 2.8 liters.

 

When I built my turbo engine, I used the 2.4 liter rods and had the piston pin height adjusted in an effort to improve the rod to stroke ratio. While I am sure it is minimally improved, I non the less can run 18 psi on pump pee with a pretty agressive timing curve according to Clark. I have flat tops 1 mm over that sit down about 10 thou in the bore.

 

Torque may be king on the street, but only to a point. Torque is what moves mass, horsepower is what keeps it moving.

 

Case in point. My friend built a poncho 455 and he did everything he could to improve torque. He advanced his cam, had a set of headers with smaller tube diameter primaries made, variable duration lifters. This is a 455 with ported ram air 4 heads, a performer rpm, a 750 holley with a proform center section that flows 850 cfm, 3 inch exhaust to the mufflers and then 2.5 after, and 1.65 roller rockers. He has a 2500 rpm stall, and 3.73 gears. Best pass is a 13.59 at 102.

 

Lj said he was stupid to worry about torque with a big block, and he should have put the cam in straight up, skipped the variable duration lifters, and ran big tube headers since his heads are set up to breathe. He also determined thru desk top dragster or whatever that he could pick up power by going back to 1.5 ratio rockers. If he wanted torque, he should have run a comp cams 268 cam, and he would have had it.

 

There is a growing group of guys racing stock appear muscle cars now that are running deep into the 12's and some are breaking into the 11's. They are running stock for the period tires, which means those old polyglass tires, and they are reatarding their camshafts to reduce torque and increase topend hp to get their times. Yes these guys cheat, but still, running 12's on G60-14 polyglass tires in an old muscle car is getting down.

 

If I had my choice and built a 3.1 liter, it would have about a 94 mm bore or so, and whatever stroke it takes to work that out. Of course I turbo, so it may not be the same for someone NA.

 

Also, Honda's have a long stroke and they are not torquey engines for their size.

 

Ok, play with my devil's advocating.

[Dan Baldwin]

Thanks, Pete. But my point was that even (especially!) at the race track, destroking is counterproductive.

 

Tomahawk, you don't know that of which you speak. My car is anything BUT a stoplight grand prix machine or dragracer. It is built for ROADRACING. Way more sustained high-rpm running than your dream road scenario. My car is WAY more a revver than a stock L24, which has peak power at or below 5000 (I know the official spec is 5500, it's also wrong). My peak power is 6500, and nobody's home below 3000. My advice: quit dreaming and get thee to a road course!

 

Lockjaw, destroking may not be a big deal to do, it's just not a good idea. As far as torque vs. power goes, power is THE important value to watch. That does not mean maximum peak power at the expense of a broad powerband is a good idea. Anyway, the point was/is destroking is a surefire way to LOSE power in an L6. If you COULD easily build a 94mm bore L6, you'd still be better off with the stroker crank vs. L28 or L24. 3456cc, man that'd be SWEET! Anyway, point is an 89mm bore 3.1 liter is an entirely practical engine build, while a 94mm bore 3.1 liter, which would potentially rev higher and make more power is not. I didn't set out to have a 3.1 liter and then custom select my bore and stroke, I just went with as much bore AND stroke as I realistically could.

Torque is pretty much a function of engine displacement and compression ratio (not really a function of bore/stroke, which is why Honda engines ain't torquey though they are long of stroke for their displacement). Where you put that torque in the rev range is up to you, via carbs/cam/exhaust. I put my rear wheel 200 lb-ft in the 4800-6200 rpm range. Wheeeee!

 

Regarding rod length/stroke, more is NOT necessarily always better. If you follow the angle between the conrod and the crank throw, you'll see that a SHORTER rod length will actually give you greater leverage on the crank through the meat of the power stroke. But shorter rod lengths also create much greater side loads => more frictional losses, wear, etc. I remember reading an old Hot Rod where they found they made more power with 5.7" rods than with 6" rods in a SBC buildup. Something to think about, anyway.

[Lockjaw]

OK well Hotrod did a new article a few years ago where they took the rods from a Ford 300 I6, had some JE pistons made, used a 327 crank to make a 350 and it made insane kind of power on 87 octane with like 11 to 1 compression. I would have to see if I even had the mag anymore, so don't quote me yet on the compression. It was a street engine too.

 

While I have modified my rod to stroke ratio a little, I talked with a guy named Jack at scorpion racing, who got all of electramotives old I6 stuff, and he told me the way to make power in a datsun engine is to use a longer rod. He said use a 5.7 inch rod. I think 240 is 5.3 or something like that.

 

I am sure there is benefit there since I don't have any issue's with detonation. I could go highr than 18 psi with a T04 rajay I used to have that bit the dust without detonation. That was with the old stock fuel injection though, not the JWT setup I have now. I am positive I have a much more agressive timing curve because Clark told me when he sent me this chip to be very careful about boosting. Whatever, I will say this, it completely changed the sound of the engine when you hit it. Totally different.

 

I guess the other nice thing about it is I already have the rods, just need to get the crank and order pistons. My friend has a diesel maxima he said I can come out and take it out of the car, I can have it. Not sure if I wouldn't rather spend 250 and just buy one and not go thru that hassle. Might have to try it just for fun.