On a turbocharged small displacement 4V street engine with just decent heads, built for operation on the street, not operating under any limitations (rules), the head is one of the last things I would touch.

Even in most lower-mid level racing classes, there is lots of room to get the other things right first before touching the head. Until you are close to winning and need the edge with most other options exhuausted, you go to the heads.

All above is meant strictly for turbocharged small displacement 2V street to light-race engines. Other engines and applications sometimes require totally different approaches.

 

I would agree with that from a budget/bang for the buck standpoint.

But if designing a true race car, especially open track or endurance, having a well flowing top-end will pay major benefits. Just for starters you'll be able to make more power on less boost => less heat =>less mass and greater reliability, which pay huge dividends on a track.

I would not argue that on a small displacement high boost street motor, focusing on more boost is the easiest way to see big hp gains, but it does come with its drawbacks as well.

 

We have four in route that are all spoken for

3 for in house builds that are here right now and one for shipment.

Anyone interested give us a call. we are only a week or so out on these.

Eric

 

for the same power you can get it alot cheaper

 

Maybe because they just came out?

Try not to be shocked in the next couple of seasons as most of the major teams start running whole Cosworth engines. They are just coming onto the Evo scene.

I personally could benefit from a 10,000 rpm redline, so they do hold value for some.

 

Yes and that is exactly what it is for because no matter what the level of racing, there always is a budget. In the mid to lower classes, budgets are always tight or burst.

Yes, but cost effectively, before you move to the head, all heat management options (they are relatively cheap) should be exhausted.

Not just boost, but heat management and flow efficiency between atmosphere and intake port entry, and between exhaust port exit and atmosphere.

 

Trojan Man you make good points on this and other threads.

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4V heads mated to small displacement engines very often do not even approach their flow limits before reaching bottom end mechanical limits. Reason for high 4V limits is inherently good design.. low valve angles, high port approach, hardly any short turn. Look at any production sport honda car head, any production sport bike head. The sport bike heads are virtually 5 year old F1 heads.

In terms of what companies do to the 4V ports, there is hardly any magic to it. It comes down to money and time thrown at solid basic design and testing, and then consistency in CNCing and hand finishing (if carried out) subsequent ports. CFD isn't used as much in port development as much as some may think. A lot of it is standard flow testing many port variations at high pressure drops. Things are a lot more difficult when you start off with a less than ideal port and try to make it flow, on an engine that pumps a lot of mass even at relatively low engine speeds. Trying to get high speed air and fuel to turn smoothly and together, is tough.

The limitations are the same in both ideal and non-ideal situations. F1 nominal port gas speeds are about the same as IRL, Champ car, GT, drag.

I do think the Cosworth head will be a lot better than 95% of the aftermarket heads out there. But the few guys who have just proper understanding, dedication, processes, and low level equipment should be able to come very close or even exceed Cosworth's 4G63 head. It all depends on how much time and money Cosworth pours into development of this head. They could crush any current 4G63 competitor at will, but till they make that decision (maybe they've made it already, but I doubt it based on the price of the head), I don't think we should just assume that these heads are the best.

Mahle makes arguably the best racing pistons, but their range of pistons that is available to the average racer at the lower more everyday price, is not exceptional by any means.

 

Hmm, so speaking of cost effectiveness, would you then say that an improved intake manifold would be the better choice over a ported head?

Also, given a 2.0l 4g63 that is built to be able to rev past 9000rpms (fuel cut at 9100) and running a maximum boost of 23 psi past 8000rpms, how would I find out if the stock Evo head is anywhere near its flow limit?

l8r)

 

Made additions to clarify what I wrote earlier. Lots of typos too.

Depends if the stock intake manifold proves restrictive when run in your specific application. Chances are it isn't as much of a limitation as too small a turbocharger for given power, poor overall component match, lack of heat control and/or lack of margin of safety in tune. I would work on those things first.

Short answer is that on force inducted engines you can't detect minor choke unless you have a test cell, and you can't calculate it unless you run advanced simulation.

Best practical approach is to assess other combinations running more flow at roughly the same pressures as you and see how they fare. And/or run some of your own tests.

Some people may jump on me and say you can calculate choke points, but but with force inducted applications especially turbocharged ones, isolating restriction alone cannot be done without very complex calculations involving a whole host of factors including exhaust side ones. The OEMs don't even run pure calculation. They run rough calculations and they too look around (cross manufacturers, models, years, within same application and output roughly) and form trends and then run some of their own tests based on both, but heavily on trends. It's far from pure simulation.

Besides, you need to define flow limit. With turbocharged engines there is an absolute flow velocity limit, but no real absolute mass flow limit (except for energy to continue to compress the charge increasingly inefficiently). Naturally aspirated engines reach an absolute velocity as well as mass flow limit at sonic choke. Wiith naturally aspirated engines you typically find minimum cross section in the intake port(s), calculate gas speeds at this minimum cross sectional area factoring mean piston speed and bore to port area ratio, or by volumetric flow, and then see if it is anywhere near mach .65. This isn't the point of absolute choke but it is roughly the point where diminishing return results in no gain and reduced fuel efficiency. With tracts under pressure, this point is moved higher because the gas is denser which still yields returns, feeding the engine at that velocity. Where exactly the point is depends on engine, intercooler, compressor, and turbine efficiencies.

 

Sorry but all of those people rev to 10k currently It doesnt take the head to do it... its whats in the head. Curt, Shep, Brent, Marco.... the list goes on and on... they all rev to (or past) 10k. I plan to rev mine to 9k or so (Worried about the stock bottom giving out... alot of Gs at that point). Major teams will run Cosworth Engines if they give them as a sponsership... otherwise race teams will continue to run what they can at a much cheaper rate (That holds just as well if not better).

Im not saying its not a great product... its just nothing special. For someone that completely grenaded thier head to an unrepairable state then sure... but otherwise what does this head do that you cant do with a stock head? Nothing.

 

One could conceivably model the stock head and apply computational fluid dynamics to determine the modifications necessary to maximize flow. That would not be using CNC to ape a hand port. I have no idea if Cosworth does this, though.

 

And as pointed out earlier, these heads are not any more expensive than other custom heads when you consider there is no core involved.

We'll just have to agree to disagree. The performance history of this company is like no other, and that seems hard for some to grasp. Maybe they will completely drop the ball with their line of Evo engine upgrades, but I kinda doubt it.

 

Thank you.

This gives me a few ideas. Although I'm not sure how I will be able to finagle/afford the necessary time/test equipment.

l8r)