jt-sport

Im sorry if i had post this topic twice ,because i dont know where to post it correctly (on competition forum or tech forum)

There is some tought (mostly the V8 hotrod community) that says roughning the combustion chamber will make a better performance. They says the rough surface will keep the homogenety of air and fuel mixture ,so it`ll make a fast burn to make a better Index Mean Effective Pressure (IMEP).
They even make several dimples on the chamber to make a little vortices of air and fuel.. (I see it on http://www.n2performance.com)
I wanna know what will happened if we use the dimples on honda engine for racing use.
Because for me (I think) we don’t need to “over thinking” about the mixture quality on high RPM engine. its better to think about the quantity (hi flow) ,and we make it with a smooth surface . That V8 people maybe use that dimples because they prefer to maintain the mixture quality on low or middle RPM of Big V8s engine. Im a true ????
Anybody have ever tried that way before (dimples on chamber) ? Can you explain me how to modified the best Honda chamber surface for racing high rpm use??
Regards

Odie Knownothing

rainforest

never tried it! but you answered your own question.with that and awelded Larger quench area your cumbustion chamber ould rox.

Dan Hill

Think about this though. As a friend pointed out the other day, a V8 makes about 1/3 hp per liter so making it more effecient isn't as hard. Making 1hp per liter as honda does calls for alot of research and if dimples would make more power, and they might, I think someone would be doing it. Porting in the right spot does make some high end power on a n/a motor, but one thing is for sure, porting in the wrong place will certainly take it away, are you a gambler??

GSR_Hacker

http://www.theoldone.com/components/cylinderheads/

jt-sport

Woww.. thanks GSR_Hacker .
I found that stuff on tha site (http://www.theoldone.com/components/cylinderheads/ ) . they put the dimples in the injector nossle area, im gonna try that to my d16 injection

But any ever seen that dimpless on carburetor engines??

non-VTEC

i just finished putting dimples into the same location endyn does on my LS cylinder head........hope it works good........

you get this weird feeling when you have a hammer and center punch in your hand hammering away at a very expensive cylinder head.......

hope it comes out ok

jt-sport

LOL ,yeah thats must be hard for you. Was that LS breathe with carbs ??

But the worst think comes to me . The night when i plan to put the dimples on the head, at tomorow morning I've found that my mechanic was already put the head on the hood completly with the injectors and running it !!.


* ..uhmm.. still wonder where to put the dimples for 4 barels carburetor engines




[Modified by jt-sport, 1:41 PM 3/10/2002]

non-VTEC

i would imagine on a carburated engine you could try to put some dimples on the intake port as well. probably at the entry point.

but with a carburator i would think the air and fuel would automize a little better than a fuel injected engine? so maybe the dimples arent that important?

jt-sport

Oh no dude !! FI make better than carbs, so we should carely more about the automize process on carbs. (especially on hi rev for me)

mm... but i think we should point the area where fuel mixture (on carbs engine) well-traveled it, then we put the dimpless there.
And im affraid if we make it with the wrong dimples configuration, it gonna distrub the flow at high rev..

anymore thouhgt bout it ??



[Modified by jt-sport, 4:28 PM 3/12/2002]

mps9506

On our 4 cyl. Suzuki engines that ran either single Weber or dual side draft weber carbs we had a "dimpled" intake manifold. It was still smooth, but had small round bumps in it to help disturb the air. The theory behind it is that with the carb we don't get very efficent atomization of the gas compared to fuel injection. So it was more important to us to have a more turbulent air flow than smooth air flow. We never polished out intake ports either, just enlarged them to get as much of the mixture as possible. On the Exhaust side we ported and polished, polishing didn't make much difference though because it became covered up anyways by soot.
I don't know how to describe the roughness of the intake manifold. It had many small bumps in it, but everything was very rounded so it felt very smooth when you touched it. It looked kind of like a cement sidewalk, but felt much smoother. I purchased my maniflds in that condition so I do not know how to go about making the finish like that however.

I am not as experienced with fuel injection as with small carb. engines but I am learning. I don't even work on any carbed engines anymore however so I can't really test anything I read anymore.