Pushrod or OHC

[megotmea7]

the ZR-1 package was an almost $30k option. cars were sold for around $100k in some cases, compared to the $35k base price for the vette at the time.

obviously there are other technical advantages which even exceed the perceived cheaper construction costs.

granted there are, as i said it is a better design, but speaking on end result regardless of the makup of the engine or technical advantages over the next, even regardless of displacement. comparing the LS1 to the M3 I6 for simplicitys sake, the LS1 is a smaller lighter engine, producing more power, more torque, and a flatter torque curve, and acheaiving better gas mileage. with those advantages does it matter where/how many cams there are, how many cylinders, or displacement, how efficient the head design is, how many valves? what advantages does the M3 motor have over the LS1? and this isnt taking into account the cheapness of the LS1 either

Maserati is developing a V8 version of the Fiat multijet diesel engine to be installed in the QP. The Brera will have a 5 pot 200 BHP diesel, you can buy BMW 3 coupe with the 330d engine, Audi delivered its previous A4 cabrio with a diesel and the list is endless.

dont get me wrong, i never said anything about the deisel, i was just trying to demonstrate the stigma against pushrods with ppls attitudes and perceptions against diesels

[megotmea7]

i prefer DOHC...i will leave it at that

i cried when a pontiac powered DP won daytona

theres that aformentioned "psycological" issue. . .

[targa]

theres that aformentioned "psycological" issue. . .

...huh?

[henk4]

the ZR-1 package was an almost $30k option. cars were sold for around $100k in some cases, compared to the $35k base price for the vette at the time.


granted there are, as i said it is a better design, but speaking on end result regardless of the makup of the engine or technical advantages over the next, even regardless of displacement. comparing the LS1 to the M3 I6 for simplicitys sake, the LS1 is a smaller lighter engine, producing more power, more torque, and a flatter torque curve, and acheaiving better gas mileage. with those advantages does it matter where/how many cams there are, how many cylinders, or displacement, how efficient the head design is, how many valves? what advantages does the M3 motor have over the LS1? and this isnt taking into account the cheapness of the LS1 either


dont get me wrong, i never said anything about the deisel, i was just trying to demonstrate the stigma against pushrods with ppls attitudes and perceptions against diesels

I put displacement in bold, because that's what the M3 is lacking compared to the LS1. LS1 is cheap because of the numbers. M3 is expensive because it is a BMW

I rambled on about the diesels just to show what is going in Europe, and mentioned a few cars that also in Europe had to fight against prejudice, but I'll buy you a drink of Ferrari ever comes up with a 4-pot diesel

[megotmea7]

I put displacement in bold, because that's what the M3 is lacking compared to the LS1. LS1 is cheap because of the numbers. M3 is expensive because it is a BMW.

the point i was making tho was despite its greater displacement, it is an overall smaller engine, this is due to it being OHV, demonstrating this advantage. and i understand the price difference im mostly because of its brandage.

I'll buy you a drink of Ferrari ever comes up with a 4-pot diesel

i used the example of a ferrari 4-cyl diesel to demostrate, how feelings towards a type or configuration of an engine may deture ppl away even if it proves superior in real world and performance scenarios. but i have the feeling you may have picked up on that.

[Matra et Alpine]

it is more expensive to have a OHC head ported than a pushrod head,

Don't see this one meg ( and a few others - stay tuned )
I can think with soem heads that porting them is more difficutl becase there are more valves or are already optimised with minimal wall thicknesses.
Not sure I can think of a head where porting makes a BIG difference and it's harder whre all other things are ketp the same.
Can you maybe expand ?

it cheaper to cast/grind one cam than 4.

A brand new custom cam from one of the top engineering companies in the UK for one of the strongest Ford competitions engines out there is the pricely sum of £140 ( about US$200 ). Now as they make a healthy profit too, then casting and machining price isn't really a major issue for those parts.
Yes, it's cheaper but does 300 quid REALLy make a difference ?

16 valves/springs as oposed to 32.

That assumes going to DOHC on a V8.
The choice to go for 3 or 4 valves per chamber is drven by other factirs and NOT the cam. only IF the engine needs the larger valve openeing area does it NEED the D in DOHC and the extra springs valves etc.
They often get put together becuase it is difficult for a pushrod system to operate on more than 2 valves per combustion chamber as they have to be angled and pushrods don't work well with multiple angled valves.
It's another discussion on multi-valve that coudl explore that decision.

and with advancements in pushrod head design such as those used on modern chevy LS engines the advantages of OHC are hardly worth the cost(both monetary cost and weight/volume)

erm, there aren't any "advancements"
Competition cars have used esoteric materials and billet components for rods, buckets, follwers, tappets including rollers etc etc
If any "advance" it's been in better fluid dynamic modelling to improve the flow of air in and out the combustion chambers - but OHC heads have benfitted from that equally so.
We are porting a 295 head for the Mini and it's funny reading what was written 40 years ago about porting it and what is known to be best today

engines such as the DOHC northstar and the SOHC/DOHC ford modualr motor have been mass produced for over a decade now. they can be had for reletivly cheap. and are used in replacement for the likes of LS and LT motors. but the fact still remains that it is easier and cheaper to buy an LT1 or LS1, build and make power out of than it is for en equivelent mass produced DOHC motor such as the mod' or northstar. its just the way things are....

Thanks meg, I had wondered if it was order of magnitude differences in volume - esp if the block is shared in trucks - or just 10% more. Another thought was does country of manufacture make a difference ? Labour costs coudl be significant - hence why the MINI ended up with a cruddy Mexican POS instead of a decet motor Any ideas ??

[Slicks]

What are the relative sales volumes of these respective engines.
It was previously raised that the LS1 is cheap because of volume.
You're never going to get a cheap Ferrari engine for as long as they stay with low volume and hand-engineered/built.
It woudl be interesting to conjecture WHAT-IF on a Ferrari or Lambo or BMW engine if it coudl be made in the same numbers and factory costs as the LS1

The LS6 is only in 2 cars (C5 Z06 and CTS-V, so its not "mass produced") and it can bought new for 2-3K over an LS1.

[Slicks]

Can you name one new design less than 10 old that is running OHV? (not the small block derivatives)

Saleen S7
BTW to clear somethings up OHV engines can have VVT.

Everyone stop and think about marketing here. Do you think that companies want people to buy their cars, or do they want to make the best performing car, ignoring customer wants and needs etc?
By a company that normally uses DOHC to switch to OHV that shows that they were previously "wrong" with the engine design, and gives even more credit to GM with sticking with that design. Its no surprise companies will go with a better marketing design, even if its less superior(not saying that it is) to keep reputiation points.

[megotmea7]

I can think with soem heads that porting them is more difficutl becase there are more valves or are already optimised with minimal wall thicknesses.

ive seen shops charge supra owners upwards of $1500-$2000 for a decent port job on its DOHC 3 liter I6 head. the 'equivelent' port on a LS is around $1200-1400.

Yes, it's cheaper but does 300 quid REALLy make a difference?

it is when your making 150,000 cars

That assumes going to DOHC on a V8.
The choice to go for 3 or 4 valves per chamber is drven by other factirs and NOT the cam. only IF the engine needs the larger valve openeing area does it NEED the D in DOHC and the extra springs valves etc.

the DOHC 4.6 mod' and the northstar are 32v engines, the LS1 is a 16 valve engine, i was indirectly comparing them

If any "advance" it's been in better fluid dynamic modelling to improve the flow of air in and out the combustion chambers - but OHC heads have benfitted from that equally so.

my point being the LS heads are the highest flowing, non big block heads ever to come on a OHV production car, the LS heads are leaps and bounds ahead of the LT heads, which werent shy in the flow department either. OHV engines have come along way since the 60's. and the end result is apearent. dont take this as me saying OHC engines havent come along, its just that OHV engines are at a standstill with 1970's technology and some ppl belive

[quote]the northstar has been in production since the 80's, the ford modular motor came out in the mid 90's, and has been used in mustnags lincolns, and in ford trucks ever since. chevy has used the 350(5.7) in its trucks up untill 2002 when it switched to the 327(5.3) the LS motors and the truck 350's were never the same up until recently when the new iron block 6 liter LS based truck motor came out for its full size pickup. i guess you could call LS motor and ford modular motor production right about the same, altho it is highly probable that ford has made more OHC engines than chevy has LS's since the highest selling pickup in the US has been the F150 (fitted with a 5.4 liter SOHC mod' motor) and mustangs (fitted with either a 4.6 SOHC, DOHC, or supercharged DOHC, or a 5.4 DOHC modular motor in GT, mach1, cobra, or cobra R form) have been outselling LS1 equiped camaro's and trans ams 3 to 1 for years. not to mention lincoln LS, crown vic's, grand marquis, etc. being fitted withe the 4.6 or in the LS's case a very small version or the modualar motor(i think around 3 liters).

[2ndclasscitizen]

i would go pushrods myself personally. the LS1/2/6/7 only need to rev to 6500rpm to get their max power, as opposed to 7-8000rpm. the LS7 generates 500hp/373kw at 6200rpm and 644nm at 4800rpm, while the M5 V10 needs 8000rpm for the same power level. whats gunna last longer when pushed, i'll put my money on the LS7.
also, pushrod motors can rev hard, ie V8 supercars have 5litre pushrods motors, getting 630+hp at 7500rpm

[crisis]

[QUOTE=Slicks]
How do Harleys "run like shit"? They "rattle" because of the lobey cams they have, and long stroke for nice torque and a beautiful exhaust not. Its not about tradition, its about what people want, they want that "rattle."
QUOTE]
You may want to rethink that last line.

[crisis]

The argument could be solved (maybe) by putting a similar spec aftermarket ohc head on the LS1.

[henk4]

Saleen S7
BTW to clear somethings up OHV engines can have VVT.

Saleen S7 uses an old engine design, my question was about brand new engines or engines designed during the past ten years.

[henk4]

i would go pushrods myself personally. the LS1/2/6/7 only need to rev to 6500rpm to get their max power, as opposed to 7-8000rpm. the LS7 generates 500hp/373kw at 6200rpm and 644nm at 4800rpm, while the M5 V10 needs 8000rpm for the same power level. whats gunna last longer when pushed, i'll put my money on the LS7.
also, pushrod motors can rev hard, ie V8 supercars have 5litre pushrods motors, getting 630+hp at 7500rpm

The BMW/Audi/Mercedes V8 diesels only need to rev to 4000 to get maximum power and still run DOHC. Read the thread first before coming back with the rev arguments.

[henk4]

[QUOTE=megotmea7

i used the example of a ferrari 4-cyl diesel to demostrate, how feelings towards a type or configuration of an engine may deture ppl away even if it proves superior in real world and performance scenarios. but i have the feeling you may have picked up on that. [/QUOTE]

I ddi not pick on it, I would greatly welcome the prospect, and also the reaction of the traditionalist who would shout about, scacrilege, blasphemy and what ever have you.