DKP & the 78 mm cranks

[louisb]

After looking at Sarge's Classic pics I strolled through the DKP member's section. I never noticed it before but a lot of the DKP cars are running what now would be considered smallish 2 liters with 78mm cranks. Sure there are a few big motors over 2.3 liters but I would say half the members are running engines 2.1 liters and smaller. Nothing real significant I guess, just found it interesting.

--louis

[Frank LUX]

Size does not Always matter...

Frank

[Shubee2 (DSK)]

Size Dose Matter    CC's equal free H.P.  There are alot of small and Big motors today  The right Combonation can get you a real Killer Mouse Motor,  My Favorite's were always a 78x88 and 78x90.5  Fk87 or K8 and a Nice set of Old Fumio,Steve Tims or Berg Heads, And You Have one hell of a Motor the 67 I Bought From Scott Bakken After I Went Threw the Motor Ran 11:70's threw the mufflers with Slicks A OCIR it was a 78x90.5 IDA's BIG set of Heads fk87  heres a Picture of it  in 11:70 Trim

[John Rayburn]

The definition of an engine is  "something that you screw your heads to"... Get the best head builder you can find..

[louisb]

The definition of an engine is  "something that you screw your heads to"... Get the best head builder you can find..

That really seems to be the common thread. How good the heads are for the engine. I see engines that are 2.3 liters with FK-89 cams and heads with 46x38 making less than engines with smaller cams and heads with say 40-42 X 39 valves.

Size Dose Matter    CC's equal free H.P.  There are alot of small and Big motors today  The right Combonation can get you a real Killer Mouse Motor,  My Favorite's were always a 78x88 and 78x90.5  Fk87 or K8 and a Nice set of Old Fumio,Steve Tims or Berg Heads, And You Have one hell of a Motor the 67 I Bought From Scott Bakken After I Went Threw the Motor Ran 11:70's threw the mufflers with Slicks A OCIR it was a 78x90.5 IDA's BIG set of Heads fk87  heres a Picture of it  in 11:70 Trim

For the '67 I am looking at something like, 78 or 82 X 94, & an FK-8. (Basically the HVW's blueprinting motor) Nothing too outrageous but will still get the car into the low 13s or maybe high 12s with slicks.

--louis

[John Rayburn]

My old 78 x 94 and 130 cam neeted me a 13.01 at Terminal Island in the early 90's... That was with a set of Jeff Denham's non welded super whammy 041's.. Jeff's work always amazes me...

[Rick Meredith]

The definition of an engine is  "something that you screw your heads to"... Get the best head builder you can find..

Now that was funny John... way too true but funny. But you're right, the horsepower is in the heads.

[Matt H]

If you remeber Dave Conklin had his 40 x 37 unwelded heads runnig low 12's. Hi Dave

[rebel]

If you remeber Dave Conklin had his 40 x 37 unwelded heads runnig low 12's. Hi Dave

Hi, what kind of bore/stroke combination did he have?

[Chuck Fryer]

If I remember correctly..........

82 x 94
FK 8
40 x 37 040 heads
10 something to 1 c/r

Maybe Dave will chime in..............









Oh yeah, I forgot to mention the propylene!!!!!!!!!!!!!!!!!

[Bill Schwimmer]

Don't you mean "Ohio pump gas"  In all seriousness Dave's car flat hauled.

[deano]

Back in the day, a 78mm crank was considered huge! And few, if only all-out drag cars would spend the extra money for an 82mm. I think if you ask any of the former Auto Haus-type counter-persons out there, that they sold way more 74s than anything else. I think the difference in price from a 78 to an 82 was something like $75 more... a lot of cash back then. Since Porsche 912 rods were the deal, pre-Carrillo, you had to wack on the case a bunch. An 82mm was considered way over the top for a street engine. Boy, have things changed.

[Sarge]

I always liked the ease and expense of building a motor with a 78 mm stroke crank...just add "B" pin height pistons and clearanced VW rods and your "basicly" ready to go.

[louisb]

Back in the day, a 78mm crank was considered huge! And few, if only all-out drag cars would spend the extra money for an 82mm. I think if you ask any of the former Auto Haus-type counter-persons out there, that they sold way more 74s than anything else. I think the difference in price from a 78 to an 82 was something like $75 more... a lot of cash back then. Since Porsche 912 rods were the deal, pre-Carrillo, you had to wack on the case a bunch. An 82mm was considered way over the top for a street engine. Boy, have things changed.

That is some interesting information. So is 3 liters the next "threshold" or do you think we will see more smaller turbo motors? It seems like there used to be more variety in the size motors people were running back in the 70's and 80's. These days it is basically a 94 bore with either a 82 or 84 stroke. You see some 90.5 x 78 but not as many people are using the 78 stroke any more. Engines these days seem to be very cookie cutter. (Probably due to the internet.)

--louis

[Rick Meredith]

I also think that a lot of it has to do with the change in pricing of the components. Back in the day, there was a lot more cost difference in running a larger motor. Now the cost is more uniform so you might as well go big.

[Jon]

I think its worth thinking over what the mass production of good heads have done to the game.
Before there was good heads to be bought, you had to use a good head porter to make you a set of heads. These heads were tailor made and usually came with some good advice to the rest of the recipe. With the head porters experience as a support the engines came pretty close to the optimal usage of the heads.

Today its a different game, or it seems to be different, if you use the sky high CFM numbers from CNC porters you whole equation is off. Its the sum of your intake/head/exhaust that makes up the engine. It still pays of to use a good head porter to set the record straight, or alternatively if you have your own long experience there is nothing better!!

[Sarge]

I think its worth thinking over what the mass production of good heads have done to the game.
Before there was good heads to be bought, you had to use a good head porter to make you a set of heads. These heads were tailor made and usually came with some good advice to the rest of the recipe. With the head porters experience as a support the engines came pretty close to the optimal usage of the heads.

Today its a different game, or it seems to be different, if you use the sky high CFM numbers from CNC porters you whole equation is off. Its the sum of your intake/head/exhaust that makes up the engine. It still pays of to use a good head porter to set the record straight, or alternatively if you have your own long experience there is nothing better!!

Well said!

[louisb]

I agree. I have been going back and forth between using a set of CB's CNC wedge ports and some hand done heads by someone. (No idea who yet.) I like the idea of the CNC head but not sure about the one size fits all.

--louis

[lowfastbus]

Don't you think the wildness of your heads have more effect on choosing the cam exhaust and carbs... instead of the size of the engine?

[Sarge]

In my case, I knew the size engine I was going to build.  I knew the cam I wanted to use. Then, when it came time for heads, I gave that information to the man intrusted with doing the porting along with what compression ratio I was planning on and whether I planned on using close ratio gears.  The heads were then ported to match that criteria. 

[louisb]

Your running stock gearing right Sarge?

--louis

[Sarge]

Yeah, stock gears and 4:12 R&P.

[deano]

Yeah, stock gears and 4:12 R&P.

Yup, when he leaves Chino, he is in first, and by the time he hits Orangethorpe, he finally shifts into fourth....