Grooves in heads/cylinders: Snake Oil or a Good Idea?

[johnc]

Ok.. go ahead and keep bashing me now.

 

I'm not bashing you. I'm just asking the advocates of combustion chamber grooves to do a test. Since you claim that this works for you, please let me know:

 

1. What were you're 1/4 mile times on either of your engines (Maxima, Camaro) immediately before you cut the grooves in the head?

 

2. What were you're 1/4 mile times on the same same engine immediately after you cut the grooves?

 

3. Did anything else get modified (besides the groove cutting) between step 1 and 2 above and if so, what were those mods? This includes simple things like timing AFR, plug gap, boost psi, etc. These changes don't necessarily invalidate the test but its something that needs to be taken into account when looking at your 1/4 mile improvements.

 

Again, I'm not bashing you, I would just like to see some data. Thanks.

Edited March 25, 2009 by johnc

[PanzerAce]

Well, couldn't find *any* L series engines at my PnP, so someone else is going to have to actually try it instead of me.

[JMortensen]

Well, couldn't find *any* L series engines at my PnP, so someone else is going to have to actually try it instead of me.

[shameless BIL plug]My brother-in-law has a bunch of heads if anyone is looking. You can email him at matmorrow AT att.net.[/shameless BIL plug]

[rsicard]

Amen...

 

I don't see you guy's able to run low 10's on 93 octane fuel on drag radials with 250cid.

I'm no beginer tuner or novice engine builder. I've been doing this long enough to know when somthing makes a difference and when it doesn't.

Ever put a screen under your carb?

It's worth a solid .4thenths in the 1/4mi on a sbc. Smoother idle better mpg.

Oh.. but that's another "Snake Oil" treatment. I see.

If I didn't get the results from doing these grooves then I'd say I didn't see any gains. But I honestly did. Before and after... Amazing. The Maxima was more impressive than the Camaro but BOTH made a difference.

 

High Compression does not make Tons of Horse Power. Period. Not enough to make a seat of the pants difference. Look at articles of dyno results if your a "Dyno" guy Raising compression from 9-1 to 12-1 is like 30-50hp. Whoopie. Now you've got to run race fuel at 7-10.00/gallon. Oh.. there's a real street worthy car..

 

Had a local guy go from 10.5-1 to 14.5-1 I laughed and said you won't pick up anything... So we made a bet. He shaved the heads got his compression up and guess what... Not a single tenth. SBC Nova 10.50 car on the bottle.

Ok.. go ahead and keep bashing me now.

UR50SLO: I believe that you are RIGHT ON the mark. High Compression does not make Tons of Horse Power! As for "Ever put a screen under your carb/" this is true also. The leader in MAF sensors will tell you that taking off the screen ahead of the MAF sensor screws up the MAF sensor characteristics. The screen straightenes and evens out the flow of air.

 

As for grooves, I have done research on other forums and the results of grooves has alway been positive. That is not to say that there is a power gain, but there is more complete and therefore must be FASTER combustion.

 

As for Mr. Singh's stating that there should be .078" between the head and top of piston, I would suspect that he ran into Internet articles where quench/squish has been optimized by way of tightening the distance between head and piston (David Vizard recommends FLAT TOP PISTONS not raised dome) and the results are FASTER BURN combustion as David Vizard and GM have already producted, proven and tested. This puts David Vizard and Mr. Singh at ODDS with each other such that neither ( I surmize) will comment about the others combustion modifications. But Mr. Vizard's methods ALWAYS come from research and testing before and after modifications.

 

The gist that I get out of the grooves is that if it creates more turbulence and complete mixture burn, then combining same with tight quench/squish will yield a more complete mixture burn.

[UR50SLO]

Sorry I got mouthy last night I'm normally very mild on boards and discuss this stuff back and forth with no problem.

 

The Maxima had 181,000mi on it when I turbo'd it. I ran 6psi for awhile all stock and kept evolving the setup as time went on.

I changed a few other little things when I had a head gasket let go at 199,000. I was expecting it to be "Blown Out" Like GN's do.. but it was a hair line part that let go just from old gaskets. All the metal/rubber intake gaskets broke apart like uncooked spagetti. So.. It needed done.

When I had the heads off is when I did the grooves,some mild port work to the intake and ballanced the air flow in the plenum. I know the exhaust temps... the timing I could run and the AFR's during lean cruze were very different from before and I can't explain it from intake/exhaust ports or plenum being ballanced.

For some reason it makes more power at WOT with 10.8-9AFR than Mid 11's AFR. Very noticable difference. I run in the mid 15'sAFR to low 16s at highway speeds/crusing around. I open loop tuned the car to acheive that AFR. Since the narrow band tends to toggle 14.4-14.9 (On wideband with all above)

You can really hold your hand on the downpipe when it's running at idle and it will only be luke warm 117deg.(lazer heat gun) Most guy's think I want to burn their hand.. So I'll put mine on there first. It's funny. With out the current 3" downpipe it went 13.40@107mph.

I can't launch a FWD car... But the MPH tells me it's making good power.

It has 245,000mi on the stock engine (with the headgaskets done at 199,000)

 

With the Camaro... Other GN guys are running similar setups as mine but have to run Alky or Meth to get the times I'm at on 93 pump gas. As far as I know if I make 9.90's this spring If I'm not the only one I'll be one of 5 or so. There's a thread on turbobuick about the fastest 93/alky cars and I'm there with out alky. I can't see how a few hundred lbs between their cars and mine .2-.3ths can explain it either.

My under hood temps are very low.

 

Every combustion chamber is different and the grooves work better on some than others. It's experimenting with it. My take on it is with the grooves when the plug fires the flame front is able to get under the shelf of the flat part quicker and more complete than with out the grooves... along with keeping the air/fuel turbulent/suspended.

There is less heat in the exhaust because the fuel that is in the chamber got burnt/used and is not then dumped into a hot exhaust pipe/header to continue to burn in the tubes (what would be left) Since there will not be 100% of the fuel burnt in the chamber what isn't burnt go's into the header/exhaust and is burnt or expelled there Which creates more heat.

The less effecent the burn in the chamber the hotter the exhaust will be.

(Flat tops/dish) work better since there is no blockage like a dome piston has. (Agreed Rsicard)

Two things on MAF's... Screens need to be left in as you said to even/streighen the air coming in to the sensor. If you put a MAF on the charged side and have a bend before it .... it'll be very tough to tune.. at LEAST 6" streight before the MAF if on charged side... I try when ever possible to put it on the non charged side.

 

David Vizard is a good wealth of info and results.. very good reading.

I'm constantly reading and learning/experimenting. I don't go to Dyno's. It's just a number. My MPH in the 1/4mi will tell me how much power I'm making and if it made a difference. Your ET is variable on launch/traction but your MPH will be a steady marker of if your changes made a difference.

Sorry for getting on the defence

~Scott

[johnc]

It's funny. With out the current 3" downpipe it went 13.40@107mph.

 

Great! That's a good time for a FWD Maxima. What was its times or mph before you did the headwork?

[rsicard]

UR50SLO: Your right on the MARK again and express it extremely well. You have made me even MORE convinced to use grooves. Now, would one groove aimed at the spark plug be enough or would two additional radiating outward from the chamber/plug area to cover the remaining area of the quench pad be better? Since you have first hand experience in this subject I will take your recommendations. The other question is what tools do you use to make the grooves? Finally, can you describe or post pictures of the BEST configuration of grooves i. e. depth, width, length etc? I have a set of aluminum heads which I am contemplating doing. Please advise. Thanks.

[UR50SLO]

Sure... and sorry again about my one post.. had too much liquid encouragement I guess.

 

Here are pictures of the Maxima head and the GN head.

I did several on each spread out a little and all pointing toward the plug.

I think the Maxima head just happens to be perfect for this procedure and uses

the grooves very well.

The GN head works good as well but the downpipe is hot to the touch... but still cooler than any other GN downpipe I've ever come across.

BTW.. I just use a triangle style rat tail file and do it by hand. THen smooth it with sand paper so there are no rough edges.

Hope that helps, Scott

Pic's*

 

[rsicard]

UR50SLO: Thanks much.

[Careless]

I could "how" this would work, but I'm pretty darn sure there's more info out there as to "why" it would not work.

 

the main thing being that so many close/sharp edges in an area like that may get so hot as to create a hot-spot within the chamber that could pre-ignite low octane gas. This is the same reason why many higher-compression engine builders would buy new forged pistons back in the day and round out the domes edges with a cartridge roll and sacrifice the small loss in compression ratio to maintain a proper burn characteristic rather than unwanted pre-ignition.

 

Have I been reading all the wrong info for the passed 5 or 6 years about this subject? Maybe I shouldn't be building a high compression 3.0 litre I6

[UR50SLO]

No to put down what you've been working towards and all and I know this will sound wrong no matter what way I state it but the short answer is no on the high compression.

http://www.popularhotrodding.com/tech/0311_phr_compression_ratio_tech/index.html

[johnc]

If your build goal is ultimate horsepower then yes, I agree that boost is the way to go. But there are many, many reasons to not build a boosted engine especially if you're building a competition engine that has to meet a set of rules.

 

I think that's where the disconnect is in this thread. On a boosted engine the little grooves probably don't matter one way or another. You can always turn up the boost. On a NA engine the grooves kill compression and quench which is critical to getting power.

[rags]

This question is for John. When doing a comparison, what would you say is an acceptable boost increase that would be attainable from the loss of compression due to the grooves? If chamber cc increase is necessary I will record that also. I ask this because the main reason for me trying this is to reduce detonation to allow more boost. A lot more boost. That being said, I would expect my mph to remain the same or possibly lower if the boost was set the same.

 

(Sorry John, you posted while i was typing )

 

Joe

[johnc]

When doing a comparison, what would you say is an acceptable boost increase that would be attainable from the loss of compression due to the grooves?

 

Its not for me to determine "acceptable" since you're the one doing the test. Its up to you to define what's acceptable to you.

 

Given that, I would like to do some calculations to determine what kind of boost increase you can get with a drop in compression ratio comparable to (but not with) the grooves. What I mean is that if the grooves drop the compression ratio 1.2 then I would want to know how much more boost and timing you can run with a compression ratio drop of 1.2 by something like opening up the chamber, installing a thicker head gasket, etc.

 

Then cut the grooves and see how much increase in boost you can get. If its more then what's calculated from just the compression ratio drop then you can say that grooves helped in some way.

Edited March 27, 2009 by johnc

[rsicard]

No to put down what you've been working towards and all and I know this will sound wrong no matter what way I state it but the short answer is no on the high compression.

http://www.popularhotrodding.com/tech/0311_phr_compression_ratio_tech/index.html

UR50SLO: I am wondering how many following this thread have read the popular hotroding article you attached. This is the one that I will most closely follow for recommendations for quench. This applies ONLY to Normally Aspirated engines. Boosted engines are another matter. Using grooves SLIGHTLY reduces compression and may likely ENHANCE the quench action.

[rags]

I would like to do some calculations to determine what kind of boost increase you can get with a drop in compression ratio comparable to (but not with) the grooves. What I mean is that if the grooves drop the compression ratio 1.2 then I would want to know how much more boost and timing you can run with a compression ratio drop of 1.2 by something like opening up the chamber, installing a thicker head gasket, etc.

 

Then cut the grooves and see how much increase in boost you can get. If its more then what's calculated from just the compression ratio drop then you can say that grooves helped in some way.

 

Too much work for me! If by chance I am able to run more boost after the mod, I'll just chalk it up to my "modified" head. If I get nothing, off it comes and the old unmodified chamber head goes back on. Either way I'll let the list know.

 

For my sanity I hope I don't see any benefit.

[UR50SLO]

I guess my point to a extent is the actual amount of gain you get from going from being able to run 93 oct pump gas with 9-1 vs the amount of $ needed to support a 12-1 engine with race fuel does not make sense for the small gain in Hp.

 

On a boosted engine which is all I do here...... your limited by detonation.

Boost presure won't kill a engine... Detonation will.

I've seen guy's with GN's/Sy/Ty's/WRX's ect put ALOT of good parts and money

into their cars but neglect the tune. They end up wouding the engine or just running

slow times.

Every engine will work with boost. It's a matter of being able to control the fuel and timing correctly and have a safe tune. If you take the Maxima as a example and go from 16.90's@78mph to 13.40's@108mph With no real internal changes and get better fuel mileage.. I don't see how to disagree with a cheap turbo system.

I used parts that were laying around my shop to begin with.

IT cost me 19.00 to boost it with 6psi. (Oil pan gasket and Brass T for oil feed) Then over the next few months I added a little more and began to perfect it as time went on and I learned more about hacking the Maxima ECU/Tuning it.

I did a turbo setup on a 98 Camaro with stock Series 2 V6. He took it to the track prior to turbo.. 16.70's and at the end of last year he went 12.70@108mph on 93 fuel. That's never had a valve cover off the engine! Injectors.. my header setup and my tune. His 18yr old boy beat the heck out of it all summer. (then hit a pole) So this winter I had to get a fenedr for him and repair/paint door.

Both the Max engine and the 3.8L buick's take boost very well in stock trim. A Yugo might not have that much gain.. Lol.. but it does do one heck of a job at making a engine effecient.

~Scott

[rags]

Scott,

 

This Memorial Day weekend I'll take the GN out to Indianapolis for the race and drop it off at your shop to see if you can find any hidden power

 

Nice work!

 

Joe

[woldson]

Ya know I may just do this as a WTF idea.

I've been following this thread (and the one year or so ago) and it just seems like it won't hurt too much on a high compression engine that I want to do.

[UR50SLO]

Anytime you want to come up on a weekend Rags and we'll tune on your car that'd be fine with me... it's fun!

You'd need to send me a list of what all's done with it now and what your goals are so we can set in place parts to make it happen.

There's been stock block/ECM car's in the 9's before!

Most guy's with turbo/downpipe/Fuel pump/injectors/chip can run high 11's-12's with no difference in reliability or mpg.

Be glad to point you in the right direction!