rons 00z

iTrader: (10)

give it time. it will happen or so i've heard

Juggernaut

iTrader: (1)

Some of the older Cobra's are capable of this too, I have a friend with a '96 Cobra with Xpipe, pullies, and 4.56 gears that runs mid 12's. Oh yeah, did I mention 7,000rpm clutch dumps?

Beavis5.3

Both valve train designs have their place, but I favor the much simpler, easier to use OHV pushrod design.

Let's look at somthing simple in this debate, power and weight.

A Ford 4.6 DOHC is bigger and weighs more than an old 460 big-block Ford, but doesn't make near the power.

Ford royally screwed up with this engine family. Yes, now they are putting out respectable numbers, but that's onyl after 12 years of development at high cost.

You average LS-1 V-8 has a better power to weight ratio than the Ford DOHC stuff.

Is overhead cam technology bad? No. Look at the old Ford 427 SOHC motor, that thing was a monster, made tons of power, and funny enough was smaller than the current 4.6L DOHC Ford engine.

Anyone remember the old Pontiac 250 I-6 OHC?

The main thing with Ford's OHC stuff is that they got enamored with high-tech comlicated stuff, and over-engineered the engine when they didn't need to. (Thank you Jaques Nasser, the man who ruined Ford!)

For those who talk about a bigger displacement DOHC making more power than an LS-1, does anyone here remember the disasterous flirtation GM had with the DOHC small block that was in the Corvettes?

rons 00z

iTrader: (10)

i know why ford stuff doesnt compare against gms because ford sucks. no but really it's about head port and combustion chamber design. like if you compare any chevy or ford v6 head to a buick v6 head im sure you'll make more power with the buick due to a better port and cc design. although i think those buick guys figured out how to use magic too.

Fulton 1

iTrader: (9)

If you're referring to the LT5 as "disasterous flirtation" then I think you need a new history book...

ShadowLightCSU

iTrader: (1)

I wonder, why hasn't anyone brought up the Northstar V8?

restoman45

iTrader: (2)

that is interesting...i would love to see a ls6 flow chart overlayed on a dohc flow chart...i woulda thought the opposite on a dohc head, i woulda thought their highlift would have been better...or is it because the heads arent designed for like over 500thousands lift or soemthin?...

ynneK

So if anything is gleemed out of this post, is pushrods are still a competative design because of cost and packaging. You can genearlly fit more displacement in an overall exterior dimensions with pushrods than DOHC, cause the heads on a DOHC engine are huge in comparison. DOHC heads probably flow better, but the extra cubes in a pushrod more than make up the difference.

The LS2 is identically the same size exterior wise as a LS1.. it displaces 6.0L and is rated at 400 hp/400 lb-ft. And its 15 lbs lighter! and it still gets great gas milage.

then there are the sleeved and stroked out 7+L LSx blocks and the C5R blocks... 'nuff said.

BTW, Feb's Hotrod magazine has an interseting article about Pro Stock and Pro Import.. One is a carbed supercharged pushrod V8.. another uses a EFI turbocharged DOCH I6... Two different powerplants from two different set of rules, inside very similar chassis and drivelines. The Pro Import car makes more hp(it like 1300 vs 1100), but slower since they can't figure out how to adjust the clutch to launch, since a turbo's are load dependent.. like trying to hit a moving target.. Plus Pro Import is relatively new.

niphilli

Best example I can think of is the 4.9L in the recently out-to-pasture BMW M5. It was supposedly a great engine....Took up more space than the LS6, worse fuel economy than the LS6, not as much low-end torque as the LS6, much much more stuff to break/wear out than the LS6. Very comprable dyno results between the two engines (except low end torque).


I hear that a good set of ported 4.6L 4V heads will flow between 330-340 CFM on the intake side...Dont know about exhaust.

I agree with you on all accounts when talking N/A::::But throw in a blower and 4.6L.

I have seen a stock '96 cobra put down 460RWHP with a 6# Vortech as the only addition (through manifolds and cats).....Not to mention these engines are strong enough to take it reliably.

I have another friend with a 97 Vortech cobra (430RWHP) 100K+ miles...she beats the **** out of it every day.

I have another friend that forged the rods and pistons in his Vobra (T-Trim) his car put down ~630 RWHP pretty reliably now two seasons into that motor. Stock heads stock cams....Just rods, pistons and 22# of the good stuff from a Vortech...

I read the other day that someone took a stock '03 cobra long block added a fuel system from hell and a big-*** turbo and put down 800RWHP.

In fairness I read yesterday that someone put down 540RWHP with a stock LS6 Long block (Z06) and a procharger @ 7psi with 36# injectors...Through manifolds and cats...->Extremely impressive but I have my doubts on the longevity of that setup VS a similar 4.6L setup.

Pro Stock John

iTrader: (34)

Some of the other engines mentioned in this thread are solid for sure, like the BMW engine.

But the LS1/Gen III engines show the excellent performance of a pushrod engine.

Ford modular stuff is interesting but to me not that innovate or efficient. I don't care how well they make power on boost I am making 746rwhp with a stock style bottom end and a blower setup. Any modern motor boosted will make some nice power. But the LS1 will make the best power stock.

Fulton 1

iTrader: (9)

Right, and this is where I lose faith in the car rags. On the one hand the numbers would indicate exactly what you're pointing out, yet on the other hand the pushrod design is considered "outdated" and "inefficient" by the self-proclaimed experts. Seems to me that this is a case where facts and data are worth more than the pontificating of experts. Like when C&D compares 4x4 trucks and spends three-quarters of the article discussing the interior and on-road ride characteristics

I've seen an SN95 Cobra (don't remember what year exactly) putting down 500+ rwhp. They had to sit a guy in the trunk because the thing kept wanting to lose traction on the rollers. From what I've seen, though, on the street many of these centrifugal setups do require a bit of spool time and so while they make the numbers on the dyno - it doesn't always translate like you'd think.

Good point. It just shows that after a certain point it becomes an apples to oranges comparison. The LS1/6 is obviously optimized for a different set of criteria than many of these other setups. I would submit, though, that out of the box the LS1 design is a good deal more highly developed for its criteria than some of the other setups we've discussed.

niphilli

The car that I was talking about that made 630 ran consistent 10.7s at 132 full weight stock suspension stock T-45 when it was dynoing 580 on 18lbs (T-Trim)... Believe me it was no sloutch on the street either (when it would hook).

Did I mention that it is still stock compression . Thats right nearly 10:1 CR and 18lbs of boost. If that is not an efficient set of heads I dont know what is.

Old SStroker

About tens day ago in a similar thread:

[QUOTE=roger]trust me it wont be to long until we see GM using 4 valve per cylinder v-8's.[QUOTE]

No quarrel there. The 32V Northstar V8 has been in continuous production since '93. The newest version for longitudinal applications (SVX and XLR) has VVT on inlet and exhaust. Pontiac is to get the 4.6L Northstar in the GXP later this year. The Aurora used the 4.0 L version, and the early IRL engines were based on it.

I just don't believe you'll see 4-valve V8s in regular GM trucks in the forseeable future. LS1/LS2/LS6 are primarily truck engines, with the truck volume paying for the R&D and tooling to have them in Vette, CTSV GTO, etc.

Here's the thread:

https://ls1tech.com/forums/generation-iii-internal-engine/130699-wat-you-think-about-32-valves-ls1.html

A few flame wars, and some misinformation, an a lot of opinions, but nevertheless interesting reading. Much like this thread.

OWENMUSTANG

iTrader: (2)

LS2 is still 2v based off of the ls6 port. new mustang gt is 300hp 3 valve based off
of the 5.4 f150 head

redmach1

Most of the things you guys say is true, but the plain simple fact is Ford did prove that the dohc cam design can make ls1 type power with the 5.4. Nobody seems to remember the 2000 cobra R which was just basically a 5.4 with dohc heads and made 385hp and equal torque. Why ford did not explore this further is beyond me. The 4.6 will always be behind the ls1 due to displacement. It takes cubic inches to fill the cylinders as well as good flowing intake and exhaust tracks. Ford did come along way with the mach1 engine in terms of efficiency. I made 281rwhp/303rwtrq on the dyno with mine basically stock and I average 20mpg (half city/half highway). Not ls1 hp numbers, but still 1 hp/cu in. at the wheels basically stock. Ls1's don't do that.

FAST LS1

iTrader: (2)

I remember the Cobra DOHC 5.4 and how it actually made more than 385hp. The problem with the 5.4 is that the stroke is longer than the bore, the 4.6 is a square engine, same stroke/bore. The 5.4 has a longer stroke to make the extra cubic inches. Having such a long stroke on a DOHC that wants to rev is a bad idea for both performance and reliablilty. I think everything in that engine was forged like the new 03 S/C'ed Cobras.

redmach1

That is true. I personally would have paid the extra $$$ to get a fully forged factory dohc 5.4 in my gt.

roger

some good things here and some things that just arent true.

the ls style engine is an awesome pushrod engine.best thats ever been made.makes great power with mods and stock and makes for a great street engine because of size(ci.)

but....what a company can do and what a company will do are two diffrent things.

the 4.6 has proved itself.if i remmember right the fastest n/a full body car is a mod engine,not a ls1 style engine.look at www.modularperformance.com

sure ford should have built it bigger even with a better flowing head 70 cubic inches is alot to catch up with.

the 5.4 would have been the awnser.this arguement wouldnt be going on if ford would have used this.and as the stroke being to much(4.16)its been used in endurance racing for quite a few years with little problems.besides ihra prostockers will spin slightly over 8000rpm with 5.5 inches of stroke.

ford did design the 5.0modular that developed 415hp and was close to production.

another consern was NVH(noise,vibration,harshness)which for the regular customer is a big deal.the 4.6 hands down is a smoother engine.trust me i know.i work at a dealership that deals with both.

cam wise the 4.6 run about 10degrees less valve duration than the standard ls1.(186-194,.392lift)this does figure into the NVH side of the arguement.its been proven that by adding the fr500 cams (204-214,.472)into a mod you pick up about 35rwhp.big increase by upping the cam to similar specs of the ls1 hmmmm.

oh and on head flow numbers,dont have any right in front of me but a very lightly ported mod engine will flow about 250cfm at .300lift and just a little over 300cfm at .500,awesome low lift numbers.

someone also pointed out al pappitos car on here,its a 5.4dohc street car that weights right at 3350 with a/c,p/s all accesories and is street driven.it made over 500rwhp and runs 10.33 at 131.awesome car considering how mild it is cam wise and cubic inches to some of the bigger cubed ls1 cars.

bottom line 4valve will make more power but its not a given.look at the old zr1 this thing would make crazy power if it were still produced today.10 years ago it was making what the zo6 is making now.thats what cubes and 4valves will do for ya.

STRIPSTAR

iTrader: (4)

yeah, the cobra r motor i believe
anyway, The double and single overhead designs support higher rpm's easier and make 4 and 5 valve heads easier also. The larger amount of valves allows air/fuel and exhaust a quicker way in or out. As awesome as GM pushrod motors are I think the DOHC may be a better design purely when it comes to hp ratings. Real world issues like cost and ease of repair are another thing.

Heretic

LS6 OHV vs LT5DOHC both 5.6l
405hp to 405hp
$5200 vs $20,000 (current crate engine cost)
OHV>DOHC