Building quench into hemi head, Motorcycle

[Truckedup]

imo, would spend the coin/time on and find/get the 4 valve Triumph conversion head...
http://www.nourishengineering.co.uk/doc ... _Heads.pdf

There are several types of four valve after market heads..And the last year of Triumph in 83 the factory made a few hundred 8 valve engines of their own design...They have more power potential and less problem with detonation...They also are very expensive, head ,new cams and pistons will push 3000 bucks... Then the extra power breaks the stock crankshaft so add another 1800 bucks for a billet crank..And since you're changing the crank, better to get a 90 degree rather than 360 degree crank for a huge reduction in engine vibration... I would very much like to have an 8 valve but just can't afford it...

[ZEOHSIX]

I think Mercedes Ilmor indy engine was used as reference previously in a similar thread.
Pics can be found:http://8w.forix.com/penske-mercedes-pc2 ... plans.html

Mercedes Ilmor piston:

You call it a "Mercedes" but, the facts are Penske had GM backing for the R&D of that motor....around 3years is what I have heard it took Illmor to develop then....GM ran into financial troubles and Mercedes swooped in with a check for a pretty much fully developed motor....if GM hadn't run into financial difficulties the valvecovers on the Indy winner would have said....CHEVROLET!

[twl]

We have done quite a lot of it.

With proper flow work, it can flow just as well as the open chamber.
We feel the main advantage is the ability to use less dome on the piston. Lighter piston, and also can improve combustion, if done right.

[Calypso]

You call it a "Mercedes" but, the facts are Penske had GM backing for the R&D of that motor....around 3years is what I have heard it took Illmor to develop then....GM ran into financial troubles and Mercedes swooped in with a check for a pretty much fully developed motor....if GM hadn't run into financial difficulties the valvecovers on the Indy winner would have said....CHEVROLET!

Not exactly my idea to call it Mercedes or any other name, and I'm fine if you choose otherwise. As the old saying goes: The engine doesn't know what's written on the valve covers.

[Truckedup]

We have done quite a lot of it.

With proper flow work, it can flow just as well as the open chamber.
We feel the main advantage is the ability to use less dome on the piston. Lighter piston, and also can improve combustion, if done right.

I was waiting for you to reply.....It's the better combustion I'm interested in, not necessarily a lot more power...

[twl]

This is the current shape that we use.
This one didn't start out as a hemi, but it is the shape that we use when we close up a hemi.
We try to avoid angled squish unless we are forced to use a big dome at 14:1, or something like that.
This chamber shown is 50cc on an 87mm bore with 535cc.

[Calypso]

We try to avoid angled squish unless we are forced to use a big dome at 14:1, or something like that.

Is that because you can use more simple pistons or is there a performance difference you have seen compared to angled squish?

[Truckedup]

TWL, what engine, looks push rod ? You need dual plugs even with the small chamber?

[twl]

We try to avoid angled squish unless we are forced to use a big dome at 14:1, or something like that.

Is that because you can use more simple pistons or is there a performance difference you have seen compared to angled squish?

No, but we work to reduce chamber volume in the head, before adding piston mass to the dome, for keeping reciprocating mass down. Also, to keep as clear flame path as we can.So, with lower domes or flat-tops, no angled squish is typically needed. We only add dome size after we have the smallest chamber volume that can support the necessary flow.

[twl]

TWL, what engine, looks push rod ? You need dual plugs even with the small chamber?

That particular head is a pushrod head for the current Royal Enfield unit construction 500/535 single.
The dirty head is a stock cast head which dropped a valve and got beat up.
The clean head is a billet head of our own design which fits on the stock engine and has a lot of improvements which nearly double the output of the machine.

The dual plug holes may be used for twin plugs, or to add a manual decompressor for easier starting. So far everyone has used twin plugs there, so I have no dyno data on the single plug arrangement yet.

[Truckedup]

TWL, what engine, looks push rod ? You need dual plugs even with the small chamber?

That particular head is a pushrod head for the current Royal Enfield unit construction 500/535 single.
The dirty head is a stock cast head which dropped a valve and got beat up.
The clean head is a billet head of our own design which fits on the stock engine and has a lot of improvements which nearly double the output of the machine.

The dual plug holes may be used for twin plugs, or to add a manual decompressor for easier starting. So far everyone has used twin plugs there, so I have no dyno data on the single plug arrangement yet.

So this is an Indian made bike and they are being raced along side the Brit made vintage bikes? The Triumph would be a lot better with a 40-60 degree valve angle rather than it's 90.. Small bore would be a problem with two valves being big enough without the 90 degree angled valves... That why the eight valve heads are offered...There are road racers getting 80-85 HP from 750cc with heavily modified stock Triumph heads...very expensive work and not in my budget..

[twl]

TWL, what engine, looks push rod ? You need dual plugs even with the small chamber?

That particular head is a pushrod head for the current Royal Enfield unit construction 500/535 single.
The dirty head is a stock cast head which dropped a valve and got beat up.
The clean head is a billet head of our own design which fits on the stock engine and has a lot of improvements which nearly double the output of the machine.

The dual plug holes may be used for twin plugs, or to add a manual decompressor for easier starting. So far everyone has used twin plugs there, so I have no dyno data on the single plug arrangement yet.

So this is an Indian made bike and they are being raced along side the Brit made vintage bikes? The Triumph would be a lot better with a 40-60 degree valve angle rather than it's 90.. Small bore would be a problem with two valves being big enough without the 90 degree angled valves... That why the eight valve heads are offered...There are road racers getting 80-85 HP from 750cc with heavily modified stock Triumph heads...very expensive work and not in my budget..

This head is for a current model which is not vintage eligible.
The earlier bikes which are also India made, but copies of the early Brit design are vintage eligible. We heavily modify those heads to be similar in function as our billet head for the current model.
We have items for all the models. I just posted that head pic to show the basic chamber shape that we use.

[gofaster]

Here's how I do it on Harleys. On the older heads the combustion chambers needed to be welded up first, but the twin cam heads usually just get cut. They get welded up if they are for a more aggressive build.