rubin

I was just curious about at what horsepower level 4 bolts/cylinder are not enough. and what do the extra bolts do? by this I mean are they specifically for more clamping force or to lower cylinder distortion, or both? will extra bolts reduce distortion? I was really curious about this because most other motors out there only have 4/cyl and ive never seen a 6/cyl block & head produced for anything else (maybe im just not looking hard enough). For example hondas have 4/cyl and people are making crazy power with them. Aftermarket blocks just use a closed deck design but it seems theres no need for more bolts.

Im actually asking this question because im messing around with solidworks and trying to design an engine and want to incorporate as much as I can in there. Im making an OHV hemi engine with some features borrowed from almost every ohv engine out there.

thanx in advance

THE_SUPRA

first off sounds like a bad *** project you are building.


to answer some questions;

many guys on here are running over 1000rwhp in 4bolt heads. i guess that you arent looking hard enough for motors with more than 4bolts per cylinder, because the hemis/most mopars have 5 bolts per cylinder, as well as all SBC's

Quickin

Its certainly more clamping force, but its also spread out over more area, so the force is also spread out to more of the surface.

rubin

i knew that mopars and sbc (and bbc have even more) have em i just didnt mention them, otherwise not many do. I also know that both chevy and chysler moved to 4 with the new engines. I worked on an old benz once and it had like 6 or so per cylinder too. i just meant in general most engines dont.

also I was curious about if theres an extra bolt on the side, wont the load be uneven because there is no bolt between each cylinder? maybe this uneven load could promote head distortion in that area? I'm not an engineer but i hope to be one one day and want to learn as much as I can. I'm a 1st year engineering student but so far havent learnt anything that I could use in the automotive realm

Stang-Slayer

iTrader: (16)

The new LSX BOWTIE BLOCK on sale March 31st from GM performance has 6 bolts per cylinder....supposively able to handle 45lbs of boost!!!!!
HOLY DOG ****! !

OKcruising

I'm gonna hazard a guess and say: stress distribution and increased load capability.

THE_SUPRA

sorry about my origional post, i didnt mean to insult you in any way.

pist0lpete

iTrader: (3)

I am pretty sure that supra of yours has 6 bolts pers cylinder. Thats why 2JZGTE's (and the new LSX block) should be able to handle boost levels approaching 40psi before head lifting becomes a serious issue.

Nate81Camaro

Yeah - that thing sounds nasty huh? "Reportably" the last LSX block you should EVER have to buy! - Did you see how many cubes you could get out of that SOB!

slowride

iTrader: (3)

No, the Supra and other import cars that are turbo from the factory still only use 4 bolts per cylinder. The thing that helps is the bore size is smaller leaving less area from bolt to bolt. My old talon made 523whp at 30psi(turbo limited) on c16 but don't think for a minute that keeping the head gasket in it is just a breeze. It's all about the tune and not mixing that kind of cylinder pressure with detonation.

Most of the guys running really high boost use either Cometic HP gaskets or metal factory ones with a copper o ring machined into the block. I'm not sure about the old benz above. Was it a Diesel?

rubin

dont worry i didnt think that at all, after I read my first post i noticed that it seemed like I thought there were no other engines with 4+ bolts per cylinder so its my bad for not saying that. as for the benz it was an old sl roadster with a v8. Ill try to get a pic of what it looked like

rubin

I tryed to find a picture of the head but couldnt, it was a 70's(i think) 350sl. but heres a a link with a picture of what the head gasket looks like
http://www.racepages.com/parts/head_...enz/350sl.html

Its a bit hard to tell which of the holes are for bolts and which are for coolant but if my memory is correct then the bolts are the two holes right in between each cylinder and one more on either side

MrDude_1

iTrader: (4)

i think you'll find most modern engines use 4 bolts because at the powerlevels they're designed for, that is sufficient.. look at the LS1.. large motor with large spacing between bolt holes, and you still have to go into four digit power numbers before its a huge issue.
remember, most of these motors are designed with cost in mind.. and it costs money to cast more bolt bosses, machine them, and run bolts into them.

if i was designing this motor from scratch, i would make my intake port optimised, and then work the valvetrain and bolts around that.. most of the intake compromises ive seen are work arounds around the headbolts... id like it to be the other way around if possible.. obviously, everything is kinda crammed together there though, so theres some give/take/design work involved... lol.