stevieturbo

Nope, the fuel we get here is either the same, or below US.

US is 93/4 PON

UK is 97 RON, different measurement method, and most definately NOT better fuel.

But for the most part most cars use 95 RON which is likely equivalent to 91 PON

In some parts of Europe including Ireland. 95 is the highest available, which is regarded as crap fuel.

Top Gear likely just sees the number and blabs a load of crap without actually reflecting that the unit of measurement is different.


As for the 6.0 making 2000hp.

It is likely possible. But comparing a 2valve per cylinder pushrod engine to a screaming multivalve engine, isnt quite the same thing. If you could build an LS that revved to say 9-10k, then perhaps ridiculous power like that could be achieve on pump, but it would also be laggy as hell, just like the smaller engines are when they are making silly power.

You can bet that if the Supra guys could easily run extra capacity safely and cheaply, they would.

engineermike

Import cars have a 4v pent-roof chamber, which IS exotic compared to a wedge.

NoGo

iTrader: (2)

Very well then. Next time I see the Nissan Sentra owner I will tell him his car is "exotic".

engineermike

I didn't say anything about the car. But yes, in comparison to an LSx, the Sentra does have an advanced chamber design. As does my Sea-Doo.

This may shed some light on the subject: "The chamber of choice of the Japanese “super” bikes (the Kawasaki Ninja, the Honda Hurricane, the Yamaha FZR, etc.) and Indy and Formula 1 engines (and the Nissan Sentra, for that matter), the pent-roof permits a flat (or even concave) piston, a cylinder head that is only slightly domed, and a centrally placed spark plug. The effect is that the fuel and air mix are ignited rapidly because the mix is concentrated tightly around the plug. That allows higher compression ratios to be used with less fear of dreaded detonation—the charge quickly burns before the detonation. There’s another benefit of the pent-roof design. Because the mixture is inflamed quickly, heat loss to cooler parts of the head is cut down so more energy is available to push the piston down."

Josh@PremierAutosports

iTrader: (11)

Larger Cubic Inches, good head and cam setup, effecent turbo. Its all about the complete package. If you start with a 427 making 500whp it is alot easier than doing it with a forged 346 making 350whp. Also having a great intercooler and a turbo working in its efficiency range. A 91mm turbo will make for power per psi than a 76mm and also produce a cooler intake charge than a maxed out smaller turbo. But in the end race gas is a cheap insurance policy for your investment (IE your motor).

chuntington101

BHP is related to Torque and Revs.So to make more power you simply need to hold the torque at higher rpm.

One thing i dont see any tuners doing is upping the boost at higher RPM. that should effectively hold the toqure curve at higher RPM and thus make more power than a static boost presure. also i would guess the cylinder presure (and thus dynamic comp. ratio) will be lower at higher rpm, so there is more 'Room' for more boost. THis is problaby why centri SC cars can run more boost than PD cars.

Chris.

99SS-T

iTrader: (5)

So alot of the foreign engines, and a 32v cobra engine for that matter, benefit tremendously from thier head design?

NoGo

iTrader: (2)

meh....suppose it depends on who you talk to.

Does it help - maybe. Is it the panacea of pump gas power? I very much doubt it.

You can make big power on pump gas on anything. You just have to build it around that goal.

98Z28CobraKiller

iTrader: (17)

It's not about power per say, it's about resistance to detonation. Peak power can often be reached before detonation. This is easier to measure with fuels like e85 that are very resistant.

When talking about making 1000 hp on pump gas (which is prone to detonation), yes it helps make more power with the chamber design as it allows more timing because you aren't using the correct fuel.

engineermike

In a word, "yes".

Stock Lancer EVO's (4v pentroof) run 20+ psi stock (with plenty of safety margin) and 23+ psi slightly tweaked on pump gas. Plenty of Sea-Doo 4-tec SC (4v pentroof) run up to 25 psi on pump gas (in a very harsh high-load environment) reliably.

2v wedge chambers can't go anywhere near those numbers. I'm no tuner, but I've found that 18 psi on a 2v wedge design even at 8.5/1 compression is on a wing and a prayer, not to mention requires a bunch of power-robbing timing retard. Get a bad tank of gas, hot day outside, fuel pump bobble, ignition timing slip, etc. and the motor is toast.

NoGo

iTrader: (2)

Both of those platforms have compressions in the 8's (too lazy to look it up).

SBC, LSx, motors are not on the verge of self-destructing at 18 psi and 8.5/1 compression. You can take an SBC or LSx motor and drop the compression to a high 8 and hit it with the high-teens boost all day. Hell, I just did a vette w/ 9.5:1 at nearly 16 psi the other day - 825 HP. You'll pick up heads before you have to excessively cut into timing due to boost.

Head design helps a smidge, but for the most part manufactures are doing the same thing we do to make these things live under boost - they drop the compression and strap a good intercooler to it.

Big power on pump gas isn't high-science with the head - For our slow turning V8's it all boils down to charge temperature and dynamic compression.

Big_Bird_WS6

iTrader: (7)

i hope to make around 1200 wrhp on pump gas with my little 377 and pushing 20psi. grant i have 10:1 compression and E85. but that is still pump gas. lol.

engineermike

Even though I totally disagree with this statement, based on experience, high teens is not the same as 23-25. And the Sea-Doo's running 25 can do it for 10+ minutes straight, versus our 10-12 second blasts.

Perhaps it's the 90-100 deg ambient conditions in the south versus R.I., which brings me to my other point. The Lancer runs 20.3 psi boost stock, which means it can run safely in 100+ deg weather, with a bad tank of gas, for minutes at a time, and still last 150,000 miles. A wedge chamber can not do this.

The combustion chamber is a huge factor in detonation resistance and, frankly, I'm surprised to see someone say otherwise. There has been extensive research and books written on this very issue.

Just another point of comparison, my ZX-10R is running 12.8/1 compression, stock. As stated above, that's with tons of safety margin, as demonstrated by the folks running 5 psi boost on them with pump gas. Can any wedge 2v chamber run 12.8/1 compression with 5 psi boost on pump??? I don't think so.

99SS-T

iTrader: (5)

I don't know if they still do it but when the cummins diesel changed from 2 valves to 3(or 4 i forget) they used a split rocker arm to open 2 valves with 1 push rod. I also recall a set of heads years ago that were 4 valve heads for the LS1. IF we had 4 valves and where then able to centrally locate the plug and change the head chamber design would that help us tremendously? Seems like that is the consensus. Thanks!

Big_Bird_WS6

iTrader: (7)

^^^^ do you mean this head.

http://araoengineering.com/LSX.htm

maybe if i built a 500CI ERL NA motor with these heads and a 102 Fast gutted out. it would make some serious power. but i would also have a 30 thousand dollar motor. lol.

98Z28CobraKiller

iTrader: (17)

I think that they look better than they work.

LSXNV

iTrader: (1)

engineer mike is dead on with chamber design as it pertains to detonation resistance and the ability to ALLOW more HP. Dropping static compression down into the 8/1 range is archaic and inefficient. It was the only way to do boost and pump gas back in the days of TRUE wedge heads. The chambers on the LSx heads of today are way more advanced with their heart shapes and butterfly shapes, but the four valve "pentaroof" is still far superior (though no longer exotic). Thats why the Ferrari's and Evo's (and those weird little Cosworths) can get away with so much boost on pump gas. But the fact remains the larger engines of our GM's can still make more power with less boost due only to their size. Simply put, the more air and fuel you can move and burn, the more power you can make. Also keep in mind that there is a replacement for displacement and its called RPM. Make that equal across the board however, and its back to bigger is better. The one bad thing about over head cams and four valves is probably the main reason why you don't see them in our V-8 GMs, and that the sheer size of the heads. I mean has anyone looked under the hood of an '03 Cobra then compared that to an '06 GTO? OHC heads are BIG and HEAVY to say the least.

engineermike

We agree that 4v pentroof is better than 2v wedge (even "advanced" wedge) on pump gas. We also agree that displacement is better for pump gas power, and the same for rpm.

How 'bout this bad-boy that combines all of the above:

http://mercuryracing.com/1350/specs/

552 cid, quad cam, 4v, and twin turbo's. 1350 hp, 91 octane, and a warranty.

NoGo

iTrader: (2)

Looks like I'm in the minority here...

I would wager that you see more high HP 2JZ's and such floating around because it is simply easier to keep them together at very high boost levels. You don't have head lifting issues, crank issues, block splitting issues like with LSx, SBC, mod V8's. Can you get around these issues, yea, but the cubic dollars start adding up.

Pointing to a 1200 HP 2JZ and claiming the head design is why it can run big HP on pump gas I don't think is correct. Does the head design help, a little. Is it the primary reason, I would vote no.....but what do I know, I don't design the combustion chambers.

TT350

Problem solved, cut a check and get to work
fabbing some mounts.