Chris Prack

OOOh this is getting good..............call him Danno!!........................

mumzer

this horsepower prickwaving is silly....whoevers fastest should show up at the track and prove it at OTC...

ps...the motor in my race car makes 476 hp normally aspirated....neeener.

J Chen

Hmmm, for a moment I thought we
were getting somewhere constructive.

BTW I thought that BIG CLAIMS & BS's
only exist here in Taiwan. Well looks
like it's no better in the States.

I spend a better part of my life in the
West & I've always felt that Westerners
are stand-up kind of people, no nonsense
& hype. What's happening to you people ?

Russ Murphy

Yeah? Well mine hangs down below my knees.
Back to the subject at hand, what do you have to do to the 968 head to bolt it up to the 2.5 liter? The altered water passage I guess, but what about combustion chamber size?

Oh yeah. One more thing. What do Z06's and Vipers and Nascar motors have in common? Lots of displacement. I'm not sure using a race series motor based on antiquated suspension and motor technology as an example here really qualifies.

J Chen

Hi Russ,
Like I said once before what Tony says
should be taken into consideration. Sorry
Tony but in this case I can't totally
agree with your view. Maybe I should
have stated that my objective is to
get to 400rwhp. I'm sure the S heads
should be able to flow enough to
support those numbers without having
to move the power band way beyond
the present limit. Besides, right now it's
only speculation. Until someone has don't
it & come out with the results, we won't
know for sure.

Songzzz

I have to agree with this. In track, how much advantage does a 16V 400rwhp have over an 8V 350rwhp 951? If its only a street car why do you need 400rwhp? I cannot undertand the kind of money you pay for PP head plus you'll definitely need a better I/M to go along. Then again, how many miles can a PP head remain PP? Might as well go for a ghetto N2O wet setup, you can have all the oxygen you want for 2 mins. Enough? Just my 02.

J Chen

Hey Songzzz,
I agree as well but my intentions in
the first place is to see whether we
can attain higher horse power without
having to spend an arm & a leg for it.
Look at what it cause you for the Lindsey
head & are you generating the numbers
that is advertise in the first place ?

Songzzz

I am using the stock head. Hey! check your PM!

Danno

JChen, sent you some email from my Yahoo account to answer some of your questions. If all you want is 400rwhp, then you don't even need to do much to your head, just turn up the boost. Your turbo is sufficiently sized to flow the required CFM to generate 400rwhp. I've got RodneyWiggin's shopping list for his 400rwhp car as well as PaulBloomberg's 400rwhp car. These guys used the following STOCK parts on their cars:

- stock intake-manifold
- stock throttle-body
- stock head and cam
- stock exhaust headers
- stock crossover pipes
- stock wastegate (Wiggins only)
- stock turbo/engine mount
- stock turbo downpipe

It's not necessary to spend big $$$ to get 400rwhp. It just takes tuning, adjusting air-fuel ratios and ignition curves to maximize the output of your particular configuration. You've got everything you need for 400rwhp, just a fuel pump and you're set to go. The whole problem with running high-boost on our cars has been trying to jery-rig generic chips optimized for 15psi. Fuel alone was tough enough to adjust with 4-**** adjusters, forget about ignition; in fact a lot of people did. But now with easy adjustments in 3D-mapping of both fuel & ignition, we're gonna be seeing a lot of people run high-boost safely.

Remember that boost exists only in the intake-manifold due to restrictions in the valve-train (valves, seats configuration, valve-stems, cam-timing/lift/duration). If you increase the high-RPM VE-volumetric efficiency of your engine to get the same high-RPM power at a lower boost, the same amount of air is entering your engine.

So two different 400rwhp engines, like Wiggins@25psi vs. Bloomberg's@22psi, may running at different boosts in the intake-manifold, but in the combustion-chamber, it's the same amount of air that makes it past the valves. That's why injectors and all the equations are sized on power-output, assuming a certain air-volume present, boost is just a way of getting that required volume into the chambers.

J Chen

HI Danno,
Thanks for the advise. Hey, the chips
that you suupplied me are optimise
for 18 psi right ? If so, would it be O.K
to run it at 20 psi ? Actually, it was
never my intention to get to 400 rwhp.
I was thinking that if we could increase
VE of the head especially at low rpm,
it would improve spool up of the turbo.
Maybe increasing compression ratio to
9:1 & running at 18 psi would be a better
way huh Danno.

Danno

"Hey, the chips that you suupplied me are optimise for 18 psi right ? If so, would it be O.K to run it at 20 psi ? "

Yes, you've got the 18psi chip with mappings for your particular turbo. You can use the retarded-ignition setting on the FQS switch for 20psi. Then add about 5psi to the fuel-pressure and that should be it. The chips are mapped for a flat boost-curve so if your turbo holds 20psi flat like 18psi, then you'll be OK. A lot of people end up having to dial back fuel in the 5500rpm+ ranges with our MAP kits because they have a falling boost-curve, but that's safer than going lean.

Under Pressure Performance

With all the controversy over which head flows what and where and when, and which is better than the other, I just want to add that there are SIGNIFICANT differences between the 8V and 16V heads. The combustion chamber design, resistance to detonation/preignition, port velocity, low lift flow from 8V versus 16V and many other factors are what determines what makes one head better suited for an application than the other.

Also, I want to address the misconceived inherent power limitations and flow restrictions of the 8V head. Whether you keep it stock, or modify it in not my focus and is not really relevant as the subject always seems to focus on the fixed limitations of the ceramic liners.

That said, we have put down in excess of 520 RWHP through a 951 head (2.8L engine) with factory ceramic liners still in place. That's 624 HP at the crank with roughly 16.5% drivetrain loss - Oh, and that WAS done with 20.5 psi of boost.

The same engine (2.8L), using a different cam configuration, previously output 471 RWHP (457 RWHP SAE corrected) and 490 RWTQ (478 RWTQ SAE corrected) at the same 20.5 PSI of boost. In this configuration the car made over 400 RWHP from 4,625 RPM to redline (7,000 RPM), at which point, the engine was still making 428 corrected RWHP.

While not a dedicated track car, this combination DE, street car's engine was built to make a lot of "average" horsepower and torque and to work well within its designed operational window. The window that it was designed to operate within was from 3,800 RPM to 6,800 RPM, and makes 403 "average" corrected RWHP within that window - Not bad.

Just wanted to demonstrate that peak numbers are great for bragging rights, but "average" numbers is what wins races. Head and cam configurations can change output dramatically, all other things being the same.

Does that mean the 8V head is better than the 16V head? - Well, not necessarily - It depends on "where" you need the car to work, and how you use the car. The BIGGEST mistake people make is to look at peak numbers only, but quite frankly, they mean very little in the grand scheme of things.

For example, in the second configuration, real world timing figures for the car were 2,200 RPM (48MPH) - 6,800 RPM (149MPH) in just 7.02 seconds, and 4,000 - 6,800 RPM in 4.07 seconds, or 88 MPH to 149 MPH in 4.07 seconds (all times run in fourth gear through a stock turbo 5 speed with 275/40/17's) - This indicates an engine that works well from the midrange to redline. This is a full metal bodied car with full interior, A/C, stereo, carpet, sound deadening, and full glass - Essentially a stock chassis with a full appointment of creature comforts.

So, what's the point? Well, in order to figure out what head will work BEST for any given application, you first need to determine how "you" plan to use "your" car, then work with someone that will help you build an engine menu designed to achieve your goals.

However, the hard parts are only one part of the equation. You can have some serious equipment, but if you do not have the hardware/software to get the car dialed in, then you basically have a really big, expensive paper weight. Danno was right on the money when he stated that "tuning" is a very key part to making power and torque.

In most cases, serious numbers will virtually mandate some form of full engine management. While there are several alternatives currently available, I am quite partial to a full engine management system, more specifically, the Electromotive TEC system. Biased, perhaps, but rightfully so, I have been selling, installing, and tuning these systems since the beginning of time. I don't want to turn this into a stand alone engine management thread, but I do want to convey that significant power levels require the tuner to have "complete" control over the engine.

While the threshold of the Motronics is constantly being explored and the confines of its limits pushed by folks like Danno, it remains a relatively antiquated system and does have its limitations. Thanks to the efforts of Danno and a couple of others, the Motronics system has been given new life and has proven to be more resistant to aging than many other factory electronics. That said, back to heads...

The real question in not which head is better than the other, but rather which head is better suited for "your" individual application. When it comes to this topic, if you ask twenty different people which head is better than the other and why, you will likely get twenty different answers. There is a reason for this - Some will answer based on his/her personal needs/desires - Others will answer based on hearsay, and still others will answer based on theory. You will likely not get the answer you are looking for, because most will not take "your" application, and "your" needs into account.

Either the 8V or 16V head can be used to make significant horsepower, but depending where and how you need the engine to work will ultimately determine which head is better for "your" application. Then you have to consider the cam(s) profiles... and the turbo... and the valve specs... and the lifter configuration... and...

Thanks for reading.

johne

Scott Gomes,
As always thank you for the very informative thread. Unfortunately though it just made me thirstier. I would love to hear you expound upon the last paragraph.

“Either the 8V or 16V head can be used to make significant horsepower, but depending where and how you need the engine to work will ultimately determine which head is better for "your" application. Then you have to consider the cam(s) profiles... and the turbo... and the valve specs... and the lifter configuration... and...”

More clarification about how each of these things affects the performance. And more specifically I would like to know what you think IS good and bad about the 16V head and what you this is good and bad about the 8v head. This can help us make a decision about which head is better for us. Once again thank you very much for the wealth of knowledge.

John

J Chen

Hi Danno,
I've got 3 bar FPR. Are you saying
to add another 5 psi over the 3 bar ?
Thanks Danno

Scott,
Thank you. Very well said.

jonnybgood

One thing that hasn't been mentioned is that the Timing belt is 5mm wider to carry the extra inertia of two cams. Compared to dual adjustable cam timing I suppose a few pulleys is of little consequence.

Do I need to start putting a pad lock on my head?