Don't get me wrong, the in block cam has it benefits... Simplicity, and heritage.. The DOHC/OHC is more of a pain to service and more cams to buy.

But the other side of me says that there is a parasitic draw on the in block cam. I also think fuel mileage is effected. I think a DOHC would be more effective on mileage and power.

 

Yes, in a year or so.

 

The one thing I like about the OHV GM motors are the simplicity in repairs. Working on the old GM 3.4 DOHC motor was a real pain, but as for the DOHC motors making more power and being better on gas, I'm not a full believer. The LSx variants continue to prove that pushrod motors can make awesome power and still get good MPGs.

 

ulimatley smaller 4 valves can provide more air flow then 2 large valves and that = more power. But it comes at a price and packing deficet.

The LT5 motivated GM to bring the sbc up to par and it has continued evolving ever since.

Cadillacs new V8 will stil be DOHC--due in 09? I think.

 

Not sure where you're going with this ... one cam takes less power to spin than four. Smaller chain, fewer sprockets is less friction. Less weight for an OHV motor is always good for overall efficiency.

 

I'm not a huge fan of DOHC V8s. As stated, OHV V8 makes enough grunt while being relatively kind on fuel.

In any case, will the GM Ultra V8 be a rival to Ford's Boss 6.2L?

 

I was wondering when they were going to come out with a new engine for Cadillac. Any idea on power and/or displacement?

 

I could care less how they do it, as long as any GM engine meets or exceeds its peer engines for NVH, power, weight, emissions, fuel consumption, and packaging size. If that means DOHC finally becomes necessary, so be it. If they can get away with pushrods, good for them.

FYI, this was a neat post I found on another web forum. It is a listing of fully dressed engine weights for various manufacturers. Next time somoene slams an engine for power/displacement, you can now argue on something I personally find a little more meaningfull, power per engine weight. LS7 rates fairly well, one of only a few with a ratio greater than 1 (Porsche Carrera GT engine is another) The attached list in the link has MANY engines, including marine, aircraft, vintage car, and diesel truck engines. And it appears to have sources listed at the bottom.

http://wheeltalk.fancal.net/?p=634

 

By the way, what are the details on this Ultra Cadillac V8? I keep hearing about it, but no one has any details. Is it a refresehd and updated northstar? Ground up redesign? What is the engine intended for, CTS, SRX, STS, Escalade? Any chance it will get to non-cadillac GM products?

 

Ground up design. Its going to have all the advances that GM has made from the Ecotec and HFV6 engines and put in motion for the V8. It looks like it will have a wide range of displacements from 4.6 up to possible 6.0+ liters. MT was talking about Caddy thinking of going twards MB's large displacement V8's.

OHV and OHC engines each have there own pro's and cons. OHC's have a percieved quality of being higher tech due to the vast use by Asian and Euro makers. OHV have a smaller physical foot print, while having large volume displacment which makes the overall package lighter then an OHC.

Back to the Ultra, it should show up in the NG STS first. With the CTS growing bigger, its possible now that the CTS can now house the Ultra V8. Id say any and all Sigma's are set up for it. Ultra is also said to be placed in the Lambda XUV's as well, and shared with Buick sedans.

 

Cool, thanks for the update. Although it is a little dissappointing to see the schedule. If it won't come until the next generation STS, I assume we won't see it for another 2-3 years as the STS just recently debuted in 2005. I wouldn't expect the next STS until model year 2010.

 

STS gets an MCE next year I believe. It could show up then.

 

I don't care about cams or valves.
I care about horsepower and relative fuel consumption. Secondly, smoothness (note: not quietness -- I like to hear the engine).

The current BMW 4.8, Mercedes 5.5, and GM LS2 all appeal to me.

The Jag V8, Northstar V8, Lexus 4.3 V8 -- they're great........for 1997. Fortunately, they'll all be replaced in the next few years.

The Mustang 4.6 is in-between. Wards is crazy giving it a 10 best (IMHO). It's decent, running on regular gas as it does, but it's beaten by several truck engines.

Oh yeah, the new Tundra 5.7 is quite something. Too bad it won't fit in any Toyota Motor car (I don't know for a fact, but am guessing).

 

Meh, its all about the cylinderheads, OHC engines have few advantages over OHV engines, but its almost a moot point, especially if your talking about the same port/valve configuration. More so in the realm of a street car. Multivalve engines typically shine in the mid and high lift departments, but seem to suffer from the cleveland syndrome (yeah I said it, Boss 302, 351, and 351 cleveland engines suck ***, and they suck *** to a whole new level, check any dictionary and right next to the word suck *** is a cleveland cylinderhead - well that is until Edelbrock and CHI did a modern cleveland style head, but I digress) and that is to say, despite having improved airflow over thier single valve counterparts, the port in and of itself is overly large with poor airflow management in the low and mid lift range.

 

poor low rpm performance from 4V heads was true several years ago but enhahncements like VVT and dual stage intake manifilds have largely elminated that problem.