ok so i race a DOHC 96 sport coupe on dirt oval track, and there was a couple others out there this year too
every one of the DOHC cars had bottom end problems with the engine, while the one SOHC car lived 3 seasons before it finally blew parts all over the track
now when im racing i run it in 3rd gear right to the rev limiter almost every time before corner entry, they go through hell
the lowest RPM they see is 4500 RPM,
anyone know of anything to help hold the bottom end together on the DOHC motor?
i use full synthetic 10-w40 mobile one and mine made it through the whole season but it was rattlin like hell the last night of racing
this is a 100% stock class, we cant even remove the stock airbox, all we can do is tune the exhaust to lenghth & put in a K&N filter
i just find it strange that the 2 engines are literally the same bottom end but the twin cam destorys itself quick,
only thing i though of is in the corner maybe the oil is hangin to the right side of the pan & it sucks air


[IMG]local://upfiles/37714/40D6A3E801074D80B902F94020C42059.jpg[/IMG]

[IMG]local://upfiles/37714/01A71182C8ED4C4DB51B50C358B3853C.jpg[/IMG]

 

Its the same bottom end on the DOHC and SOHC. but the pistons are slightly diffrent. As far as I know they use the exact same crank. Only thing I can even somewhat think of is maybe the higher compression of the DOHC is causing things to come apart.... Thats a real good one. I am intrested to see what kind of responses this gets.

 

my understanding is the SOHC has a smaller chamber head than the DOHC but they have the same compression ratio,
but yea just the dome of the piston is higher on the DOHC to get the compression back up from the higher volume chamber in the head
this is something weve been trying to figure out for a while with these race cars - i dont think the 20 HP difference is gonna destory one that quick
i did hear that the DOHC motor tends to airiate the oil more

i'll throw in a couple more pictures

[IMG]local://upfiles/37714/4A0DCDE8B25A440FAC8B66EF4DD02004.jpg[/IMG]

[IMG]local://upfiles/37714/D36581F084B243D28EB172774CE1E531.jpg[/IMG]

 

the dohc and sohc have a different compression ratio...and the pistons are the same shape, but the dohc has seats for the valves in the top of the piston

 

The SOHC has 9.8:1 and the DOHC has 9.6:1 compression ratios.

The DOHC is somewhat prone to rocker failure, and does not quite have the same reputation for bulletproof racing reliability that the SOHC enjoys because of its more complicated valvetrain. It needs to be babied quite a bit more.

Nice pics by the way.

 

the valvetrain actually stayed together, the bottom end is a different story, lol
how does a 2.4 hold up to high rpm,? might sneak in a n/a 2.4 to get the torque i need to pull off the corner better
no i cant do that that's cheating...[8D]

[IMG]local://upfiles/37714/33A9BCF8CDC74071B2FB36EDCD5749A0.jpg[/IMG]

 

The 2.4 should hold up nicely.

 

i wonder how much different they are as far as sensor hookups , i guess id have to get the ECM and wire harness from a donor car

 

If you are referring to the 2.4 swap, then you would use a DOHC neon PCM and neon wiring harness.

 

well its already a DOHC so i guess evrything will go right together then, sounds like an idea, i know they use the same head, and the block is the same general design
maybe ill give it a shot