Any other time i would agree hehe, im just saying what i heard.

 

Take all that money instead of making a "modern" LT5, just twin turbo the LS7

 

My bad on this. I had thought there was at least one exotic motor with 4 cams per bank. However, I still wouldn't call a V engine with DOHC quad cam, that is unless it was purely for marketing.

 

I'm surprised someone hasn't copied and "sweatshop-produced" lt5 heads. Even if they were the ultimate in high HP they have a def cool factor!

 

Interestingly I just read a blurb or two in MM&FF when they asked Jack Roush about the drag pack Mustangs, essentially Jack said it was a mistake for Ford to adopt multivalve technology as far as the street was concerned and that they should have concentrated on an pushrod motor like GM and DCX instead, otherwise he said the die was cast and the mod motors are pretty good, they have crate engines in the works all the way up to 6 liters.

 

That's funny! Jack Rousch should know what he is talking about.

 

Multivalve engines are great in a ***** to the wall sort of way, but IMO I can agree with his thinking as I see it. Airflow technology has advanced to the point where even 2 valve engines can make gobs of power all over the map and in the region that most engines operate on the street, multivalve engines are overkill (btw they typical shine in the mid lift plus range), unless of course you are handicapped by a 3.550" bore as mandated by some short-sighted asshat that wanted to stuff a V8 in both RWD and FWD configurations forcing you to go to a multivalve layout to be competitive again only to be handicapped by stoke limitations further limiting the over all displacement of the motor unless you add additional cylinders again only to be handicapped by a dip**** CEO who thinks a certain car should only have a V8 when it could've had a smok'n 5.8 to 6.8 liter V10 - but I digress - Anyways I think part of the low speed delimma of multivalve engines stems from both port volume and a lack of quench in the combustion chamber, something a well designed 2 valve engine doesn't suffer from.

 

I always thought that multi-valve engines lacked swirl, something that you don't have a problem with in a two valve engine.

 

Or tumble for that matter, one of the tricks used on the Ford 3v is a shutter in the intake port to promote tumble. All this tumble and swirl stuff is really to keep the air/fuel mixture homogenized until you can get the revs up where the air is flowing well enough to keep it in suspension.

 

I will say this: the ZR-1 with a B&B Triflo at 7000 rpm was the best sounding car I've ever owned, hands down. I loved that engine and would have loved to see it developed further.

 

How do you guys even FIND 2 year old threads to dig up???

 

Yes I was surprised when I clicked on new post and saw myself quoted. I didn't even remember saying that

 

I didn't really think tumble was a problem with multivalve heads? I know it was in a CHP magazine, but they talked about the 4 valve SBC heads that I don't think you can get anymore. I thought it was the designer of the heads said that tumble was very easy, but swirl was hard to work with. With only one intake, the air will naturally, to a point, slam into the cylinder wall and create swirl almost without trying. On multivalve heads, it takes some work to get this to happen since there is valves on both sides of the cylinder wall. The air does not have to try as hard to fill the other side of the cylinder, like with only one off center intake valve. I agree on the second part about the air/fuel mixture.

I do have a question, if Ford has a problem with it, why didn't they fix the heads with a new design instead of putting a band aid on it? I don't see anyone else having problems with this, but then again i don't frequent any OHC performance boards so maybe its not just a Ford problem. I know the 4.7 Chrysler motor has the same problem as the Ford and I think there are some similar problems with their V6 OHC motors, which would explain why they don't get that great mileage.

 

I would really like to get that book. Does it cover the 475hp lotus variation in any detail?