DOHC vs Push Rod

[rarson]

I can't believe there are NO comments on the Pattakon VVA system.

With a little effort we could have TRUE infinitely variable valve actuation.

Honestly, I am not that impressed with my VVTi. With cams in the no overlap mode the intake closes WAY late and exhaust opens WAY early. With maximum overlap the opposite occurs, the intake closes too early and exhaust opens too late for high RPM power optimization. All the system does is change the phase between the two cams.

I would entertain replacing my system with this one. The trick on our engines is finding room between the lobe and valve for the VVA assembly. My thought would be a single lobe cam with the lobe between the valves.

Come on guys, think outside of the box here. Read the link.

It looks awesome. I think it's quite an ingenious thing. As for your VVTi, Nissan made SR16VE and SR20VE engines which was basically intake and exhaust cam V-TEC, and the cams actually switched one at a time (exhaust I believe was at like 5200 rpm and intake was like 7000). I've got a video of an SR20VE on the dyno and it's interesting to hear the change in exhaust... and then another!

Also, Nissan made a few cars with a special blue version (I believe it's called the N1) of the SR16VE, which made 200 hp, edging out the F20C of the S2000 in the hp/liter bragging rights. This was back in '91, too.

 

[JBrady]

Hi all , I'm a new memeber on here so won't get into the technical stuff , but over here in Aus I can go down to my japanese importer and buy a Celsior/Crown front cut with a 1uzfe in it and worlds best auto with everything needed to make it run for $2500.00 , that give's me a relatively economical engine that has a forged steel crank cross drilled and webbed case's , forged rods and pistons making about 300 HP that will easily last 500,000 K's !!
And who cares if it only lasts 5 years as I can get a bare motor for $1200.00
Try and build a small block Chev motor for that !!
Ask a small block Chev owner what his steel crank cost him and thats just for an engine , add in the cost of an auto and fuel injection !!
Just down the road is the worlds best GT40 kit car builder and a second hand ford 4.6 quad cam motor is $8000.00 with limited supply !!
I won't get into if the Ford is better than the 1uzfe but it certainly won't be any better , plus factor into the equasion buying a system to run the injection and a front cut for $2500.00 is looking awfully good , that leaves about 6 grand to spend on the 1uzfe to come up to what the 4.6 Ford engine would cost .
There's a lot of dyed in the wool hot-rodders over here fitting 1uzfe engines in their early fords and chev's , a lot of it being cost and the other bit is they will pass emission tests .
And most of them are also using the auto's and those that really want a manuel are fitting manuel aftermarket valve bodys .
Some of them a running twin turbo's with up to around 800 HP plus with out touching the bottom end !!
It's pretty hard to beat the word's best production v8 in a front cut for $2500.00 , even if it is "only" a 4 liter .

Some in the US have purchased complete 1UZFE engines for under $500. The reason being is there is little demand for the engine here. No one (hardly anyone) in the US is building them and the engine rarely ever fails so the demand for replacement engines is nil.

Just a little FYI, the engine uses powered metal rods and cast pistons. The rest of your statement is correct, forged crank, cross bolted 6 bolt maincaps, strong aluminum block and heads. Great potential. Problem is upgrade parts are VERY rare. Only now are camshafts becoming available.

It would cost more to buy an LSx than a xUZFE but less to build the LSx. LSx upgrade options are stagering including well over 7 liter combinations.

 

[Lextreme II]

No one (hardly anyone) in the US is building.

Except one person.... is building those motors. LOL... Obviously you have seen my LS400T built motor and right now I trying to build build a 2UZFE iron block motor with Chevy H Beam rods and custom pistons with few other engine mods. I think the more R&D we do, the more people will build up those motors. Even just with forged pistons, the engine can really handle good horsepower.

The weakest link in the 1uzfe would be the pistons
the weakest link in the 2 & 3uzfe would be the pistons and rods.

As for my project. The short block mods and labor is $1,350 and here is are the quote:

2UZFE SHORTBLOCK
Price Quote

1. Main
a. Bore out 10mm to 11 mm on the main cap. The stock main caps have 4-10 mm holes already. You need to bore out from 10 mm to 11mm (All 5 Main Caps)
b. Grind the side of the mains to fit into the block if necessary (All 5 Main Caps)

2. Block
a. Clean and spray paint the block to silver color.
b. Machine the block to about.415” wide and ¾” deep to compensate for the bolt main caps. (All 5 Main Caps)
c. Drill and Tap two additional 11 mm holes to convert two bolts to 4 bolts main. Total of 10 drill and tap holes. Holes should be drill for ¾” deep
d. Bore and hone the block .015” over

3. Crank
a. Grind .043” off the stock 1uzfe crank to compensate for the Chevy 327 with standard rod bearings

4. Rods
a. Grind .038” off each Big End (BE thickness) of the Chevy Rod to compensate the crank (.019" each side)

5. Installation
a. Install pistons and rods
b. Crank and main caps


Here is a partial spreadsheet for my project. Of couse i didnt paid $2,200 for the Carrillo rods. I paid $450 for them. However, I just put everything in retail price. Its much easier for everyone. Like JBrady stated, its much cheaper (I got one motor for $200 and the other $275) to buy a 1uzfe motor but very expensive to build.

 

[Kiwi.in.aus]

Thanks for that Brady , I'd always though the pistons were forged .
Engines fromthe US are much more expensive over here , only now are Mustang front cuts and such appearing , there's a lot of these engines going in various cars and being left standard , a while back guys were/are putting 5 L or 5.7 L holden engines in patrols , landcrusers and hilux's and the purchase price of the engine was 5 grand or more just for the engine and it was still a 2 valve pushrod engine that was not very economical .
I myself found out about 1uzfe's when I fitted one into a mates 116 mercedes benz , what a vechicle that was !!
Taking in mind that I paid $2500.00 for the front cut and to do the same with something from the States or a holden 5 L would have cost about $7500.00 and thats without a loom or dash !!
You guys over there have got it so good !!

Regards...Rich

 

[ChrisV]

yeah, here in the US, I can buy a Chevy 350 that runs for about $150. it may be a smogger motor, but a copmplete rebuild kit (with any streetable comporession piston) runs about $500. Aftermarket speed parts are dirt cheap (complete cam and lifter kit is about $125), and if youy ant to buy used intake manifolds, carbs, etc, they are all easily available.

Let me put it to you this way, for the Grassroots Motorsports Magazine $2004 challenge (where competitors have to build cars for under $2004 total, including purchase price of the car, then compete in drag race, autocross and "concours") one of the competitors brought a '74 Nova that ran 10s in the quarter using a built up Chevy small block. And the budget list proved how little it cost.

The nearly 400hp Ford 302 I had in my RX7 cost me a grand.

A BRAND NEW 425 hp small block Chevy crate engine is only $4800

http://www.sdpc2000.com/catalog/120/products/156334/ZZ383-425-425-HP-383-Small-Block-Crate-Engine-with-Aluminum-Heads.htm

In my personal Mercury project, if all I was concerned with was cheap hp, I could build a 600 hp/700 lb ft of torque Ford 460 for about $1500 using new parts in a used engine. Last one I built was a daily driver for over 10 years.

They are all internal combustion engines. All have their plusses and minuses. All of them can (and have been) used successfully. People need to stop treating them as a religion, and build what they like without resorting to insulting every other method.

 

[rarson]

I love the GRM yearly challenges. Those cars never cease to amaze me.

I think a lot people that get into cars through their own car are like videogame fanboys. They talk a lot of crap about everything else and only THEIR car or THEIR engine is the best. I think the root cause is that they are just unhappy with their choice and are trying to convince themselves that it really is the best car ever (or engine).

Either that, or they're just ignorant (not necessarily in a bad way, some people just haven't been exposed to various engines and cars). Personally, I think a real car guy can find something to like in just about any car. Engines are a little different, but not much. There are so many engines that I'd love to build to put into different cars that I would probably make myself broke ten times over, and still wouldn't have enough to finish the damn things. LS1, 1UZ, 4G63, 2JZ, 20B, all great engines for their own reasons.

 

[ChrisV]

Yeah. I'd bet that in many cases, their first car was a total POS, slow, beat up, cheap, etc, and they ended up hating it (and thus anything even remotely resembling it) and then they got an example of some other car in good shape, found that it was faster, better handling, and generally in nicer shape than their previous car, and decided that it must be the best car in the world. Saw it a lot on the RX7 forums, only compounded by the fact that have one unique thing they can hang that near religious experience on, the engine.

 

[The Flea]

Yeah. I'd bet that in many cases, their first car was a total POS, slow, beat up, cheap, etc, and they ended up hating it (and thus anything even remotely resembling it) and then they got an example of some other car in good shape, found that it was faster, better handling, and generally in nicer shape than their previous car, and decided that it must be the best car in the world. Saw it a lot on the RX7 forums, only compounded by the fact that have one unique thing they can hang that near religious experience on, the engine.

Very astute observation. Your last two posts nail it down pretty good. I'd like to contribute but most of the good points have been said already.

 

[MidShipCivic]

Let's look at a coule of engines for comparison. The pushrod Chevy DZ302 in the '68-69 Camaro Z/28 and the K20 2 liter DOHC VTEC 4 cyl in the Honda S2000.

A Honda S2000 has an F20 for 3 years and an F22 - on ... Only RSX,Civic and Accords have k-series.

SR20ve n1 was a race motor S2000 is a production car.

 

[Peewee]

Feel free to correct me on this, but I doubt you'll have a hope in hell of doing this on a pushrod motor.

 

[ChrisV]

Maybe, but I doubt I'd ever need to, as I'm not limited to 3.5 liters of displacement to make my power from. Pretty as hell, though.

You think that engine would do well in a dual purpose daily driver/track day car?

I made 600hp N/A for $1500 with a streetable pushrod motor. Feel free to correct me, but I doubt you'll have a hope in hell in doing that with a small displacemetn DOHC engine.

They all have their place, and in the application you posted, it's the best tool for the job.

 

[JBrady]

yeah, here is a hunk of cr@p 2v pushrod V8.

Little thing, only 3.4 liters.

No wonder it could only manage 1000hp and win Indy in 1984.

http://www.haascnc.com/CNCMag/PDF/v4i12.pdf

 

[MikeMan]

yeah, here is a hunk of cr@p 2v pushrod V8.

Little thing, only 3.4 liters.

No wonder it could only manage 1000hp and win Indy in 1984.

http://www.haascnc.com/CNCMag/PDF/v4i12.pdf

I see you a 3.4L CART engine and raise you a 1500HP 1.5L DOHC 16V L4 design from the early 1980's.

http://www.research-racing.de/bmwturbo.htm

Turbos are the great equaliser.

NOTHING can match the specific power generated by the 1500CC engine in qualifiying trim.

Even a big block drag engine does not make 1000BHP/Litre in specific output.

 

[rarson]

SR20ve n1 was a race motor S2000 is a production car.

There are a number of people driving around with N1 motors in their cars. Those are a lucky few, purely because of the small volume of production.

This thread is getting pretty funny. I think all of this just goes to show that the engine out of context is worthless. While there ARE better engines for certain applications, in a lot of instances, there are several engines that can do the job, and it's up to the factory (or the car guy) to decide which one they like best. Pretty much every motor has it's tradeoffs. Just decide what you want and what you're willing to give up.

That Toyota motor looks BEAUTIFUL. I'd like it to have a little more displacement, but I understand why they built it how they did. Impressive engine!

 

[SCV8]

From my experience, bent pushrods have been a pita, and wouldn't consider that arrangement again until something else comes along that would eliminate even that possibility.
I do like that over center, variable rocker shaft design, would be afraid of hammering from excess lash in the direct application as shown however.
The CART engines had been using a follower such that the cam lobe was not directly over the valve, but over to the side, acting on a follower that pivots on one end, and acts on the valve on the other end. I would imagine F! is the same, but can't comment.
TRW did an engine back in the seventies that used solenoids for valve actuation, used a card in the dash for programming the action.

 

[JBrady]

I see you a 3.4L CART engine and raise you a 1500HP 1.5L DOHC 16V L4 design from the early 1980's.

http://www.research-racing.de/bmwturbo.htm

Turbos are the great equaliser.

NOTHING can match the specific power generated by the 1500CC engine in qualifiying trim.

Even a big block drag engine does not make 1000BHP/Litre in specific output.

Mike, the F1 Turbo era was amazing. Shame they outlawed turbos in F1 it would be very interesting to see how much MORE power they could have found. Turbos definitely rule. The MB above was of course turbo but boost limited as were all the Indy turbo engines. The pushrod engine enjoyed a larger displacement and higher boost.

Regarding specific output, as mentioned above an RC engine claimed output is impressive at over 600hp/liter NA on a nitromethane blend. Of course at 42000 rpm the specific torque is only 79lbs/liter which is about the peak output of a stock vvti 1UZFE.
http://www.storacingproducts.com/cgi-bin/trolleyed_public.cgi?action=showprod_S21BR

 

[ChrisV]

From my experience, bent pushrods have been a pita, and wouldn't consider that arrangement again until something else comes along that would eliminate even that possibility.

So you trade off bent pushrods for the possibility of a stretched chain or broken cam drive belt that might allow many valves to come in contact with pistons. I've never had a bent pushrod in a performance pushrod engine, but I have had a cam belt go on an interference engine and require a pretty much entire new engine.

That's not stopping me from using a DOHC engine in my current project. I mean if we used what could possibly happen as a rational for what we liked or didn't like, there'd be nothing left TO like.


And as impressive as that BMW turbo engine is (or the Honda 1.5 liter putting out 1400 hp, but running on Toluene), it'd make a pretty crappy street engine. And the cost it took to make it put out that power was amazing, too...

See, once again, the specific oputput is in relation to a racing class that regulated displacement. Take a 1.5 liter engine with a few normal tweaks to it, and it's easy to get 140 hp from it. Run it on Toluene and stuff the equivalent of 10 times as much air through it, and making 10 times the power seems a given. it's merely holding it together at that level of boost that's impressive, not the specific output (which is skewed by the fact that it's artificially moving as much air as a 15 liter engine). Interestingly enough, the Kaase-built Ford big block in mountain motor drag racing displaced 727 cid and made 1600 hp with carbs and no nitrous, turbos, or supercharging. So basically THAT engine made more power while moving less air than the F1 BMW or Honda engines. And IT would be a pretty crappy street engine, too...

 

[MikeMan]

Mike, the F1 Turbo era was amazing. Shame they outlawed turbos in F1 it would be very interesting to see how much MORE power they could have found. Turbos definitely rule. The MB above was of course turbo but boost limited as were all the Indy turbo engines. The pushrod engine enjoyed a larger displacement and higher boost.

Regarding specific output, as mentioned above an RC engine claimed output is impressive at over 600hp/liter NA on a nitromethane blend. Of course at 42000 rpm the specific torque is only 79lbs/liter which is about the peak output of a stock vvti 1UZFE.
http://www.storacingproducts.com/cgi-bin/trolleyed_public.cgi?action=showprod_S21BR

I am aware of that.

However 20+ year old F1 tech and the Drag boys are JUST getting to that sort of specific power from a 2v Pushrod engine for a max of 30 secs before a full pull down happens.

Now the F1 motor at that boost was not a long distance engine by any means but they had to do 4-6 laps that could be anything from 4 minutes to 12+ for 6 laps of Spa or Hockenheim.

I am just pointing out that DOHC (and the mutlivalve layouts that that allows) when taken to ultimate ends is a better arrangement for making big horsepower.

Now big torque comes from displacement, not a lot else apart from FI (which is adding capacity in real terms) even comes close.

 

[rarson]

Pushrod engines tend to be 2-valve engines, which helps them produce more torque down low (the 4-valve design would be why most DOHC engines make their power higher up). Many people like the low-end torque of pushrod motors for their daily drivers. I personally am not a big fan of the big torque powerband. I like the high powerband, accentuated by boost, of my Eclipse better. Of course, the 4g63 is a LOT torquier than your average 4-cylinder, as it should be with a proper turbo.

As ChrisV continually points out whenever the discussion comes up, it all comes down to the use of the car and the person's preference.

 

[Toysrme]

OHC is more efficient. With ohc if you want more valves, there is pleanty of space on the cam for more lobes.

In the end who actually gives a crap? It's still a camshaft... You can put whatever profile you want on it. It's still a head... You can port & put new valves in them & come up with the same amount of flow.
It's such a stupid debate. DOHC with 4-5 valves a cylinder is always going to win stock vs stock, or stock vs mild modifications, sometimes stock vs a good amount of modifications, but once you get into serious cam, port, & valve changes, it doesn't matter.



Case in point, DOHC 2.5L 2vz-fe VS SOHC 3.0L 3VZ-E VS DOHC 3.0L 3VZ-FE. Tho sharing block codes, nothing between a 3vz-e & 3vz-fe is interchangeable, but it's a good example.
2vz-fe 158bhp@5800 152ft/lb@4600
3vz-e 150bhp@4800 180ft/lb@3400
3vz-fe 200bhp@5800 204ft/lb@4600
Look at what cam profiles do. You can make more hp with a 1/2 L smaller engine. The 4 valve head 3vz-fe doesn't just have a lot more bhp & ft/lb at mid/high rpm. It makes more down LOW also... over 100whp at 2000rpm, 85% of peak torque comes at 2500rpm & doesn't drop under 85% until peak horsepower is met.

I would also like to address the fact that pushrod engines make more power down low, while OHC makes more power up high. That's a load of crap. The cam profiles on most pushrod engines are setup for low rpm power, while most OHC engines are not. You pull that camshaft out & put another in and that pushrod engine wants to make all it's power at a mid-high rpm range. Pull the camshafts out of the OHC engine & put a new set in, you have an engine that wants to make all it's power at a few thousand rpm.






I like DOHC better... You have room for as many valves as an OEM possibly wants to put on the engine & varriable valve trickery is simply insane. It's also a hell of a lot easier to service. Anyone ever had to adjust a Toyota lifter bucket under 300,000 miles? I don't know anyone that's done it either LoL!