Grooving the head for better detonation resistance - my.IS

IceCold4x4 · 06-22-2006, 03:12 PM

Ok I posted a little tid bit on this idea earlier in another thread but I figured this might need to be tossed around here a bit.

It involves cutting a groove in the cylinder head directly across from the spark plug to induce a change in turbulence and supposedly shoot a jet of fuel / air mix at the spark plug. this groove is maybe 3 mm wide and 2 mm deep I belive.

See good results on volvo 8 valve heads. Seen this used on a few Small Block Chevy's back in the day too.

Here's some links to get the juices flowing

http://www.turbobricks.com/forums/sh...ad.php?t=66779 - some examples of it on volvo redblocks.

http://www.somender-singh.com/ the original site

Just curious to see what some more knowledgeable people on here think.

I'm planning on doing it along with megasquirt to the volvo later this summer. I'll report back then if the two make some good results I'll seriously thing about putting the IS under the knife for some grooves. The volvo guys are loving these it looks like. There's some debate on placement other than the 1 firing at the plug to improve turbulence but then again you are getting into some serious thermodynamics there and well a bit over my head untill the next round or two of engineering classes.

kponti · 06-22-2006, 06:58 PM

Very very interesting. I cannot stop reading about this. If this actually works (which it seems to do for the Volvo, VW, Ford and Chevy guys among others), this will eliminate the need for a head redesign for better detonation resistance. The IS300 head is very prone to detonation so this might just be worthwhile to do when the cams are going in

kponti · 06-22-2006, 07:18 PM

And i especially love this analogy, makes even more sense about flame front travelling in the combustion chamber
http://www.divineimagination.com/gal...llery.php?p=57

IceCold4x4 · 06-22-2006, 07:25 PM

I know, I've been obsessing over this for the volvo as I've gone through 3 sets of plugs here lately because of the heat, and resulting pinging / detonation. I mean 25 degree's of static advance is VERY good for a carbed motor. This is what the Les guy on turbobricks has shown with his first design which is just the 1 groove. I mean it's kinda out there. and I'm really curious as to it's benefits under boost in the IS. Because If you sized a turbo to push what only 12 lbs You could have it spool at around 2500 which is really low, i mean turbo lag is no issue, AND you could still run 10:1 compression. And have a real beast of an IS with probably a safe 350 RWHP with the right engine managment. . . . just something to think about y'all.

It is diggin' into the motor rather deep, and well most of the people on here that pay to have things done will probably never do it but, there are those like kponti, and maybe brian and das that I'd love to see do some testing. The IS is reserved to daily driver status for me now so I can't afford to test it just yet. Though the Volvo is going to have it done soon. I'll see how much it raises the detonation limit with boost. As i've maxed out now at 14 - 15 psi depending on temps.

This is probably in the wrong forum to really get noticed, I'd love to hear what Mo, Jeff, and others have to say on the idea, as they are the ones that have had the heads off and may know more. . .

HyperMKIV · 06-23-2006, 12:35 AM

we used to do this on the ford 5.0 for a while. fel-pro sells a gasket specifically for this application.

i didn't go to that link yet...but does someone make a gasket for this application??? if not, then i'm not sure how it would work...

IceCold4x4 · 06-23-2006, 06:58 AM

No gasket is needed for this modification . . . . .

kponti · 06-23-2006, 08:36 AM

Quote:

Originally Posted by HyperMKIV

we used to do this on the ford 5.0 for a while. fel-pro sells a gasket specifically for this application.

i didn't go to that link yet...but does someone make a gasket for this application??? if not, then i'm not sure how it would work...

Yeah Icecold is right. No gasket needed for this. You give about 1-2mm room from the gasket into the quench area (squish as some call it) so your gasket is fine.

From the flame front patterns I saw (pics) I will say one of the main benefits is that the slits allow the squench area to be a part of the combustion process. It also creates a place for air/fuel to be squirted out into the cumbustion front and create even more turbulence in the compression stroke. So help on two fronts from what I am seeing will definately help decrease detonation at low rpm, high throttle application. What I dont know is the help it can give at high rpm when you are already at wot? Well better mix but that will work if you have more than one slit. I would say maybe 3 or 4 slits can help at all rpm, but one or two may not be enough at high rpm.

I can also see how power can be gained with the right amount of slits after a tune and timing advance......

Very interesting things, bookmarked it and will be watching it.

I know the effects of being able to increase trubulence in the combustion chamber. That idea has been seriously capatalised on by several head builders like Trick Flow. By altering the angle to which the intake tract enters the combustion chamber, they were able to fit larger valves and increase swirl by a lot (increasing turbulence). As a result, the TFS heads are one of the most detonation resistant heads I have ever come across. I remember knocking with stock heads with 14 degrees of innitial advance. With a head swap alone, I was able to run 18degrees of initial advance on get this.....87octane fuel with NO knock. Just by being able to mix the air and fuel better.

So if this is touting better turbulence, I will say that can help NA and turbos make even more power. Probably help turbo guys get back to stock timing curves with over 400rwhp.

IceCold4x4 · 06-23-2006, 12:06 PM

Does anyone have any pics of the combustion chamber? can't seem to find any decent ones to illiustrate the grooves on th IS head