Combustion chamber size

[JBV-HEADS]

SS402,

You are right in that the dome inhibits the flame front. However a reverse dome helps it. It now has more unfettered area without quench to slow it down until it hit’s the cut up to the piston top. This upward turn now acts like our space shuttle. It directs the flame front into a direction useful to us. Right into the flame front that should be coming straight down from the edge on the head chamber. We now have that little extra thrust needed to increase torque and HP. For another parable, a glass of wine. Pour it into an empty glass in the center. The wine will head to the side and then it’s inertia will force it up the sides. Its this same motion of an expanding flame front that gets forced back upward into the flame front (if designed right) that should be being forced down. These are just some of the games that are played in chamber design. Different shapes, cuts, depths, valve placement, spark plug placement all contribute to different needs and techniques. Add blower, NO2 or turbo and you add another component to the mix that must be accounted for.

For the most part 2 valve chamber design is dead or stagnate. With Feulings death and his patents, along with Singhs circling of quench patents and finally NASCAR’s desire to not let too much change in chamber shapes has removed any incentive to continue. There are a couple of designs out there that use stock aftermarket valve trains but there is no money to bring them to market. I doubt that they ever will. With the death of us older guys, it will be a 4 valve world. Good luck,

Joe

[JBV-HEADS]

Mini,

I’m sorry I missed your post. For the boosted crowd it is all about volume. Get the absolute most you can get in there and find a way to burn it. I will present this as a thought and thought only. Some believe it may be amount of fuel and air, and not distance from head to piston that makes these detonation spots. A good quench of .040 in a NA motor may be because of air fuel mixture density in a blower motor similar to a .070 quench in a NA motor. This would usually be a problem. Now if that motor were .070 in a NA motor, with the added fuel density in the blower motor it would act like a .100 NA motor and we would be back into a safe area. This is only a thought and someone with track records and championships in blower motors would be a better person to talk to about this. My extreme endeavors are mostly in the NA world and I feel more comfortable there. I’ll let the blower, NO2 crowd expand more on this subject. Again sorry I missed you and I’ll answer Pms and emails tomorrow. I want to go out to eat tonight. Good luck,

Joe

[DrillDawg]

http://www.dragbike.com/dbnews/anmviewer.asp?a=3260&z=4

I believe that the JE pistons are turbo pistons made to be in the hole plus an .80 gasket/spacer will be added to the base.

DD

[Rizzle]

Would the location of the quench pad in relation to the combustion chamber have any measurable effects? Since the small chamber/rev. dome piston combo would have the quench pad aimed more towards the middle (if not there completely) whilst the large chamber/flat top would have the quench pad/flow along the piston top.

Could there be a benefit to having angled quench pads towards the middle of the chamber on a domed piston like some 2-stroke bikes?

[DrillDawg]

Hell, if the diesel guys had it their way, all gas engines would by flat heads and all the combustion chamber would be in the piston, works for them why not for gas engines .

Until there is more unlimited racing, everyone will just patch up existing designs to suit their chosen limited racing pursuits. With no real money behind a design, any good new design will die a slow death. It will take a system (head, piston, chamber, ect) to make any real progress over what we are using now. Look at F1 and MotoGP (about 50 cuin w/+4HP/cuin), 4v, DOHC, add VVT and variable intake tracks, 2 or 3 injectors to be used at different rpm and or reasons, ect.

Just like the flat head ford, the writing was on the wall when the OHV engines showed up. The writing is on the wall this time is for the 2v, pushrod, carbureted engines.

When the small block chevy of the DOHC injected engine shows up it will be all over for the pushrod.


DD

[PackardV8]

When the small block chevy of the DOHC injected engine shows up it will be all over for the pushrod.

Yes, that's what everyone said when all the competition went to DOHC 4V engines and GM came out with that antique LS design.

No, DOHC is not particularly new, having been around for 100 years now. Since then, most every clean-sheet racing engine has been DOHC 4V. However, racing has always had classes. Racing has always had cost concerns. Racing sometimes tries to link the race cars to production cars to get manufacturers involved. Racing in the US has favored pushrods 1,000,000 to 1. Sometimes, it's not about what's perfect. It's about what is at hand. Ford won Le Mans several times in the '60s with pushrod engines, running against fifty years of DOHC 4V development. Spend enough money polishing a turd and that will be one fast pushrod turd.

Maybe, it is horses for courses. For ultimate efficiency and ultimate performance, yes, DOHC with variable valve timing will always be superior. As far as cost per horsepower, packaging and maintenance, give me an LS any day. This from a guy who drives DOHC 4V turbo family cars, but builds antique pushrods. Don't own or build LS, but despite all the negatives from the weenie press, the past few years has shown GM made the correct decision to stay with 2V pushrods.

jack vines

[new engine builder]

Hell, if the diesel guys had it their way, all gas engines would by flat heads and all the combustion chamber would be in the piston, works for them why not for gas engines .

Until there is more unlimited racing, everyone will just patch up existing designs to suit their chosen limited racing pursuits. With no real money behind a design, any good new design will die a slow death. It will take a system (head, piston, chamber, ect) to make any real progress over what we are using now. Look at F1 and MotoGP (about 50 cuin w/+4HP/cuin), 4v, DOHC, add VVT and variable intake tracks, 2 or 3 injectors to be used at different rpm and or reasons, ect.

Just like the flat head ford, the writing was on the wall when the OHV engines showed up. The writing is on the wall this time is for the 2v, pushrod, carbureted engines.

When the small block chevy of the DOHC injected engine shows up it will be all over for the pushrod.


DD

I.M.O., there will always be a place for a 2 valves,pushrods,and carburetors.
Just look at NASCAR very big business,or any guy's that run a dirt car on a Friday or Saturday night.
In about 1983 they tolds the U.S. would go all metric by 1990 and guess what I have just as many std. tools in the tool box as metric tools.

[DrillDawg]

When the small block chevy of the DOHC injected engine shows up it will be all over for the pushrod.

Yes, that's what everyone said when all the competition went to DOHC 4V engines and GM came out with that antique LS design.

No, DOHC is not particularly new, having been around for 100 years now. Since then, most every clean-sheet racing engine has been DOHC 4V. However, racing has always had classes. Racing has always had cost concerns. Racing sometimes tries to link the race cars to production cars to get manufacturers involved. Racing in the US has favored pushrods 1,000,000 to 1. Sometimes, it's not about what's perfect. It's about what is at hand. Ford won Le Mans several times in the '60s with pushrod engines, running against fifty years of DOHC 4V development. Spend enough money polishing a turd and that will be one fast pushrod turd.

Maybe, it is horses for courses. For ultimate efficiency and ultimate performance, yes, DOHC with variable valve timing will always be superior. As far as cost per horsepower, packaging and maintenance, give me an LS any day. This from a guy who drives DOHC 4V turbo family cars, but builds antique pushrods. Don't own or build LS, but despite all the negatives from the weenie press, the past few years has shown GM made the correct decision to stay with 2V pushrods.

jack vines

I agree with you Jack, that's why I said " when the small block chevy of the DOHC injected engine shows up", meaning it's not here yet.

The LS chevy is just a polished turb with mixed DNA, Ford Y-block design including cross bolts, ford Hi-riser style intake ports, chevy style crank and rods, modern castings, and fuel injection, just one step from DOHC. Add a couple of ECOTEC heads and you would have that to .

DD

[DrillDawg]

Hell, if the diesel guys had it their way, all gas engines would by flat heads and all the combustion chamber would be in the piston, works for them why not for gas engines .

Until there is more unlimited racing, everyone will just patch up existing designs to suit their chosen limited racing pursuits. With no real money behind a design, any good new design will die a slow death. It will take a system (head, piston, chamber, ect) to make any real progress over what we are using now. Look at F1 and MotoGP (about 50 cuin w/+4HP/cuin), 4v, DOHC, add VVT and variable intake tracks, 2 or 3 injectors to be used at different rpm and or reasons, ect.

Just like the flat head ford, the writing was on the wall when the OHV engines showed up. The writing is on the wall this time is for the 2v, pushrod, carbureted engines.

When the small block chevy of the DOHC injected engine shows up it will be all over for the pushrod.


DD

I.M.O., there will always be a place for a 2 valves,pushrods,and carburetors.
Just look at NASCAR very big business,or any guy's that run a dirt car on a Friday or Saturday night.
In about 1983 they tolds the U.S. would go all metric by 1990 and guess what I have just as many std. tools in the tool box as metric tools.

I agree with you, and yes NASCAR is a business and it's limited racing, but they will be going to fuel injection at some point, and people don't like change for whatever reason.

Toyota did not make a nascar engine but they did not let that stop them from designing one.

As generations go by, the pushrod will be forgotten only to be used by die hards and not for real racing.

DD

[pdq67]

"When the small block chevy of the DOHC injected engine shows up it will be all over for the pushrod."

You missed it!

It came and went like the moon in the sky! The old The GM 'Vette, Lotus, Merc. ZR1 LT-5 DOHC engine. Only thing it had in common with our old beloved SB's is it's bore centers and lifters so go figure!

AND don't call an LS- engine a SB!!!

Cost too much and it also had some other little-bitty problems.

pdq67

[DrillDawg]

"When the small block chevy of the DOHC injected engine shows up it will be all over for the pushrod."

You missed it!

It came and went like the moon in the sky! The old The GM 'Vette, Lotus, Merc. ZR1 LT-5 DOHC engine. Only thing it had in common with our old beloved SB's is it's bore centers and lifters so go figure!

AND don't call an LS- engine a SB!!!

Cost too much and it also had some other little-bitty problems.

pdq67

That's what I'm talking about, when a DOHC injected engine comes along that is excepted, cheap, easy, everyone makes parts for, ect, and not expensive junk the pushrod will go away.

Edelbrock built his business on the change from flatheads to OHV manifolds.

DD

P.S. I did not call the LS a SB, I called it a polished turd.

[JoePorting]

The bottom line is that as long as pushrod motors are cheaper to make, they'll keep making them.

[DrillDawg]

The bottom line is that as long as pushrod motors are cheaper to make, they'll keep making them.

Or if they are not written out of the rule book. Those who limit racing will rule what is used.


DD

[JoePorting]

I meant production motors. As long as pushrod motors are cheaper to make for GM, Ford, etc..., they'll keep making them. Wallstreet makes all the rules.

[DrillDawg]

I meant production motors. As long as pushrod motors are cheaper to make for GM, Ford, etc..., they'll keep making them. Wallstreet makes all the rules.

I'm not sure, but I think that all of Ford's new engine are OHC.

DD