http://www.prostreetonline.com/buy/c...cylinder_head/

First of all, I see that the Cosworth head is about $4300. That said, I'd like to leave the cost-per-HP and money-better-spent-elsewhere arguments out of this thread and, instead, concentrate on what exactly it is that this head has to offer.

The main differences over the OEM head is that the intake ports offer a 15% increase in airflow while the exhaust ports flow an additional 31%. Likewise, the exhaust valves have been given a 3-angle valvle-job and all valves are bumped in size by 1mm.

I know that the largest benefit is going to be seen in a FI application, however, I'd really like to get an idea of what sort of gains would be seen on a NA motor... ...especially in relatively stock form (with MREV+, headers, cats) and the stock compression (piston and rod upgrades are suggested and 11.0:1 pistons are available, along with more boost-friendly 9.5:1 (I think).

The MREV+, headers and cats should really compliment the increased flow of the Cosworth head, but I'd like to know what sort of gains would be seen if simply bolted up to a stock motor (or one with this combo), as it's a complete, bolt-on affair.

I'm not about to drop $5K on the motor any time soon, but I do like to investigate all NA options, as I'm pretty determined to stay NA.

 

The Cosworth heads & pistons may start getting some play soon, from both the NA and FI crowd. I noticed that the pistons were announced in SCC Magazine this month.

While talking about the speculation on changes in the VQ's displacement, SCC's article on the GT-R states that Cosworth has been doing a lot of VQ developement work for Nissan.

 

Static airflow on a flow bench cannot be 100% correlated to dynamic air flow because of the air temperature differences [expecially exhaust] and exhaust pressure.

When you run out of things to do inside block you shift to heads.

33-40% more [hotter] airflow with only a 20-25 HP parasitic loss from a supercharger or 15-20% more air flow from better heads without the parasitic drain..........either way you need to up grade block components to achieve oem like reliability.

With heads you are stuck with the engine family, with a supercharger at least you can rebuild them FREQUENTLY and swap to other engines.......not 100% sunk costs.

Obviously some rich flolks will use both and end up with $25-35,000 engines plus a few spares for reliability.

 

If I make it to swapping the heads, forged internals and upgraded valve-train will be part of that build. I'll be taking these other steps not to pull the most power possible out of the combination, but rather to have a higher durability margin.

Are you saying that the block needs to be sleeved or otherwise prepped for an MREV+, heads (11.4:1?), internals, headers, cats and reflash combo?

 

I am more interested in what actual flow numbers for the heads are, like what they flow in cfm at 0.100, 0.200, 0.300, 0.400, and 0.500 valve lift at 28" of water. Say 15% increase means jack squat if all you get is 15% increase at 0.400 valve lift. I want the flow increase down at 0.200 and 0.300 lift as well... you know what I mean.

Heads will give you a big gain on a N/A engine. On a turbo car again they will help out huge. Roots or twinscrew blower they may not make a huge difference since it controls the amount of air entering the engine, but it will reduce back pressure and for a given blower rpm show less boost pressure.

I will look into these... are they useful for 05 engines and are their cams for 05's yet? I am a little behind the times for what is available for these cars.

 

I know this is a little hijack, but I'm getting these heads put onto my g35 6mt soon, I just put down my 50% deposit to Brian Crower because he's building me a stroker kit for my car,

http://www.briancrower.com/makes/nissan/vq35de.shtml

I'll have the 4.15L stroker kit w/ a 100mm bore, 88mm stroke billet steel crank, 81 compression aluminum forged pistons, steel billet rods, and tons of other goodies but it'll be about 6 weeks until I even get the parts, then labor, installation, getting all the other parts and BS parts as well, and I will probably be done in a few months. Hopefully this setup won't max out my GReddy TT's that I have on the car right now. Either way I figure it's only fair to keep you guys updated on how everything turns out! Good luck to whoever might be doing something similar as well!

 

I just have one question for now... do any of these parts - Cosworth or Crower, work on the REVUP motor?

 

I talked to the Cosworth people at Formula D this weekend, and they're also coming out with a new intake manifold. They showed me the computer rendered design of what looks somewhat like a big oval shaped donut. The manifold splits into two separate sides a bit after the throttle body, with three runners per side, and then reconnects on the opposite side. They said they will be debuting it at this year's SEMA show. It'll be interesting to see cost/gains/etc. on that piece as well.

They were hard to nail down as far as gains for the heads went since there would be so many variables involved. The best guess they gave me for a N/A engine (the route I'm staying) was around 40 hp if all of the basic bolt-ons were already in place. Not too shabby, but still pricey for the cost of the heads and labor to install.