Valve lifters…solid/hydraulic/roller tappet/flat tappet?

[xb-60]

Originally Posted by RICK LAKE

xb-60 Glen I know of 2 guys running them in street car. The clearance is important, good oil pressure and IMO warm up the motor before driving any where. Up side quicker spinning motor, down side less bottom end to start car from stop. It's a trade off. Flywheel weight is also important on which way you want to go. The lighter the flywheel the less stored power to move the car. heavy flywheel you can release the clutch pedal at idle and the car will move and not stall. I started with a 40 pound and the car had bottom end torque and can blow the tires off the rims. Now I have a bigger motor and lighter flywheel, still have the same problem of too much bottom end torque. I will advance the cam to kill some of the bottom end. Aluminum rods in a street motor will go 20-30K miles if everything is done correctly. This is a street motor making 250-400 flywheel hp not a top fuel or funny car making 9,000 hp on nitro. Another thought is Honda 1.88 rods. Prostock run them to 9,400 rpms. If money is no issue titanium is the final answer. You are looking for an rpm range, these are some ways to get there. Depend on weight of rods, pistons, bearings, rings, piston pins and oil you can lighten the crank shaft weight to. I will say that a 4 bolt main caps or a gridle for all the caps is needed period. As for 8 carbs or throttle bodies, with the right camshaft, 114 LSA, you will pick up 10-30 hp and about 15-20 ft of torque. With a small motor you shouldn't run out of air in the 7,000 rpm range unlike a 427 BB on 48mm webers where 6,800 is about the limit. Big tricket is getting air to bend into the throats of the carbs and not having a lean condition in the back ones. The air will get dirty the farther back it goes from passing over the other bodies. Pressurize air box helps stop this. Later Rick L.

Rick, sounds like something (for me) to avoid in a street car. Makes you wonder how much the rods grow as they heat up! I think as Brent has already said a well balanced forged steel rotating assembly is a good starting point.
I have experience with Webers on another car, and set up correctly (this is a factory setup) they have almost no downside. I believe that the Dynatek FI is even better.
Cheers,
Glen

[blykins]

Put a 4.10 gear in it and then rev it to the moon...

One of the guys running one of my street/strip 347's says that it will pull to 7000, but it hates low rpms and hates being lugged around. That's with a 4.30 rearend.

The VTEC engines are different in that they can change the cam timing at will....something an old pushrod V8 can not do.

Keep in mind that the Fox body Mustangs had excellent power and response at 1500 rpm. But they peaked at about 4800.

I'm not against spinning an engine up...I like it too. But combining an engine that likes to rev with a car set up to cruise at low rpms is where the issue is.

What would I do to compromise? Put a 3.54 rearend in the car, put the peak hp rpm at 6000 and shift at 6500. You still won't have agility at 1500, but it will be closer to what you want.

Rick Lake is humoring you in the fact that he's showing what it takes to make reliable horsepower at high rpms. However, he'll also tell you that the engine needs to match the rest of the combination.

[AL427SBF]

It was said here, and it is said everywhere ...
There's No Replacement For Displacement, we've all heard it many times - to the point where it sounds like anyone who says it hasn't taken the time to really evaluate "the situation" about making power. When someone says There's No Replacement For Displacement, right away you think "ok, this guy ain't gonna waste his time with this, he's taking the easy way out". That's too bad, sure it's a common catch phrase that rolls off the tongue easily, but it carries with it so much more. That phrase comes from some exhaustive motor tweaking by the best motor builders in the world. These guys have run every permutation and combination of stroke, bore, redline, comp ratio and God only knows what else. I'm sure the genesis of that early work was the desire to come up with a new formula for engine performance. Fast forward after millions of hours spent wrenching, millions of $$ spent on parts, millions of trips to the dyno. In the end, they all became members of the There's No Replacement For Displacement brotherhood. Take it with a grain of salt, so deserving from its' casual delivery. Then after you've been around the block with those "better ideas", you'll recognize this wisdom and be ready to join the brotherhood
----

[xb-60]

Thanks AL427SBF, but surely it depends on what you're trying to achieve? How would this apply to what I'm planning if I'm not on a horsepower chase?
Cheers,
Glen

[olddog]

Air flow is what makes Hp. Well actually gasoline, but you can only put in the amount of gasoline that you have air to burn. Air fuel ratio has to be right.

The head is the largest factor limiting air flow. Exhaust and intake restriction can make a good head useless, so they too are very important. So these three in unison, pretty much sets the upper limit on Hp.

Eventually the valve size limits the heads flow regardless of how good the ports are. Ultimately the bore limits the valve size. Therefore in the end the bore diameter defines the ball park the engine will be in.

The stroke (within a practical range) is meaningless, when it comes to peak Hp. However the torque, is a whole different thing. The shorter the stroke the higher the rpm where the peak torque is made, and conversely the longer the stroke the lower the rpm where the peak torque is made. Also the shorter the stroke the higher the rpm where the peak Hp is made.

Since the Peak Hp is the same regardless of stroke, the short stroke engine will make less torque than a long stroke engine. Experiments have been ran on a lab engine, where the only variable that was changed was the stroke (2", 4", 6" strokes were used). The peak Hp was the same in all three strokes and occurred at the rpm which gave the same mean piston speed. In other words, the 4" stroke hit its peak at 1/2 the rpm of the 2" stroke and the 6" stroke occurred at 1/3 the rpm. Likewise the 4" stroke made twice the torque and the 6" stroke three times the torque of the 2" stroke.

Playing with valve timing is a rob Peter to pay Paul game. It can move the torque curve up and down the rpm scale, but you always give up torque on one end to get a bit more on the other. The better the heads, intake, and exhaust allow an engine to breath, the less games are needed by the cam.

So the old engine muscle tended to be big bore and short stroke, to allow bigger valves. Canted valves, and Hemi heads was a way to cheat the bore and get bigger valves.

Bottom line: a 289 or 302 can make as much power as a 347 (even a 427W). You have to spin it faster, and it will make less torque, but it will make the Hp. However you do have to gear it down to run the same speed at the higher rpm, in order to have the same performance from the cars perspective.

[zrayr]

very nice post olddog.

Z.

[xb-60]

Agreed. An excellent description. And the good thing about these cars with the power/torque available and the weight of the cars is that there are significant enough margins in the power and torque figures to allow compromise to either to achieve the required goals.
Different story of course if you're chasing ET figures, but we're not all doing that.
Cheers,
Glen

[blykins]

Well, I disagree about the cam timing "games" and about the bore determining the ballpark the engine would be in. I'm also curious as to what lab engine was used, that allowed a difference in stroke by 2" increments.

I play the cam timing game on every engine, not necessarily trying to move hp/tq curves around, but trying to clean up the bottom end manners on street engines. Advancing cam timing helps attain a clean idle, more vacuum, better throttle response, etc, etc. Even on heads that flow over 400cfm, I play that game...

As for the bore determining the ballpark, we have to watch what generalities we use. Remember, the Cup guys are making 900 hp with a 4.125" bore. That is very small compared to the 4.360-4.600 bores of a factory and aftermarket 460 block, and extremely small compared to the Mountain Motor bores.

However, XB, what he said really doesn't help your mission statement. His last sentence is true, especially about spinning it faster and getting less torque. That's what happens....the higher the hp peak goes, the less torque and usable power you get. Adding displacement and stroke helps that because it makes the torque curve broader at lower rpms. Taking away stroke makes the engine very peaky and you get nothing down low.

We were discussing the VTEC engines the other day.....remember that those engines are zippy, but the transaxles also have 4.4:1 final drive ratios and overdrive gears.

[xb-60]

I would be quite OK with spinning up a 289 or 302 faster and 'compromising' on torque. And if my proposed gearing doesn't work adequately - and I agree, it would be very much a compromise - then a diff change isn't the end of the world. The way I see it, there's so much more to a Cobra/replica ownership than just bare hp or torque numbers, or acceleration figures (or even max. rpm figures!). There is so much that has to be a compromise because the basics of these cars comes from a design rooted in the '50s and '60s. These are cars that don't have a roof even....the driver is so much more in contact with the noise, the smells, the feedback. To me, speccing an engine for torque on a Cobra replica is like speccing in power steering and air-cond. and a really quiet exhaust.
I'm on somewhat of a learning curve here and I am actually sponging up most of what I'm reading, and I appreciate all comments even if I don't automatically agree with everything presented.
Cheers!
Glen

[blykins]

I agree. You don't need as much torque in a lightweight car. I will encourage you to get some common Cobra curb weights, as everyone tends to think that a Cobra weighs about 2000 lbs. Some of the kits, especially when you add in a full tank of gas, driver, etc, will hit closer to 3000 lbs.

Let me remind you that I've never stressed a high horsepower or high torque engine. What I have stressed is that you forget about picking a random rpm number that you want to achieve and concentrate on making the car usable in the rpm range that you will be in the most.

You can not have a 289/302 that will have great manners and power at 1500 rpm and still make peak horsepower at 7000 rpm. It's just not going to happen.

An engine that makes peak horsepower at 7000 will not only require a 7500 (or higher) shift rpm, but the camshaft required to make peak horsepower at that rpm will pretty much insure that you won't have much at off-idle rpms.

Again, I'm just trying to help.

[zrayr]

Originally Posted by blykins

"................. You can not have a 289/302 that will have great manners and power at 1500 rpm and still make peak horsepower at 7000 rpm. It's just not going to happen.
An engine that makes peak horsepower at 7000 will not only require a 7500 (or higher) shift rpm, but the camshaft required to make peak horsepower at that rpm will pretty much insure that you won't have much at off-idle rpms. ......."

not trying to be constantly argumentative, but........ you don't need much power at 1500 rpm in a lightweight car. A stock Hi-Po flat tappet cam in a 289 K code engine will be quite happy idling at 900 rpm and pull cleanly to the maximum power rpm which is 6000 to 6500 rpm. With just a little head work you can get usable HP beyond 6000 easily, and up to 7000 (or more) is not difficult to achieve.

If the OP wants a 7000 rpm engine, then it seems that once opinions are voiced in the negative, it's would be helpful to set aside any reservations we might have and offer concrete ideas on how he might proceed.

That's why I suggested earlier that he should build a 289 FIA dead-on replica, and then drive the snot out of it. Once he's done that, he will know what, if anything. he will have to change in order to have the car he envisions.

Z.

[blykins]

Z,

It's not all about how much power you make down low, it's about how easy the engine will run and cruise down that low too.

From his description, he's wanting an engine that will cruise around right off of idle but then make peak horsepower at 7000.

There is a difference between making *some* power at 7000 and making *peak* power at 7000. If you just make *some* power at 7000 and the peak is much lower, then there's no use at all in straining the engine and putting undue stress on it at that rpms. Just because you can see 7000 on a tach doesn't mean that you haven't lost 50-75 hp by the time you get there.

I've given many concrete options for him in previous posts. And again, I'm not trying to be negative, but I'm trying to offer advice that comes from experience.

I agree with you 100%. I think it would be more worthwhile to put the peak down lower, say 6000 rpm, then see how the car behaves that way. If it's not suitable, then parts can be swapped.

[undy]

600 rpm idle, 1000 rpm cruise, tremendous off idle power, 7100 rpm rev limit & spins up faster than an aluminum rod destroked 283... sounds like he needs a LS7...

It CAN be done... (given enough $$)

[blykins]

Yeah, other engine platforms offer easier ways....and an LS7 is larger than 302 cubic inches.

[undy]

Originally Posted by blykins

Yeah, other engine platforms offer easier ways....and an LS7 is larger than 302 cubic inches.

Other platforms? Pushrod?

Just think how quick that Ti rod, 4 1/8" bore SB would spin up with a 2.70" stroke crank. That'll give you one mean a$$ 289 (around 450hp) , and a $3000+ crankshaft bill to boot.. It would be interesting.

[blykins]

Other platforms as in modular Ford V8's with variable cam timing, etc.

The poster wants to spin it up, but he also wants to cruise at off-idle rpms with a 3.07 rear gear.

[olddog]

Originally Posted by blykins

Well, I disagree about the cam timing "games" and about the bore determining the ballpark the engine would be in. I'm also curious as to what lab engine was used, that allowed a difference in stroke by 2" increments.

I play the cam timing game on every engine, not necessarily trying to move hp/tq curves around, but trying to clean up the bottom end manners on street engines. Advancing cam timing helps attain a clean idle, more vacuum, better throttle response, etc, etc. Even on heads that flow over 400cfm, I play that game...

As for the bore determining the ballpark, we have to watch what generalities we use. Remember, the Cup guys are making 900 hp with a 4.125" bore. That is very small compared to the 4.360-4.600 bores of a factory and aftermarket 460 block, and extremely small compared to the Mountain Motor bores.

However, XB, what he said really doesn't help your mission statement. His last sentence is true, especially about spinning it faster and getting less torque. That's what happens....the higher the hp peak goes, the less torque and usable power you get. Adding displacement and stroke helps that because it makes the torque curve broader at lower rpms. Taking away stroke makes the engine very peaky and you get nothing down low.

We were discussing the VTEC engines the other day.....remember that those engines are zippy, but the transaxles also have 4.4:1 final drive ratios and overdrive gears.

Bill the lab engine was a single cylinder, designed for experimental work like this. I believe it was a flat head design. The professor that wrote the book I am referring to had formulas for calculating power and fuel consumption for every type of internal combustion engine know to man. Radial air craft, turbine, diesel, 2 strokes, and even two pistons running in the same bore. It was interesting.

I do not 100% believe everything that was written. The book was written 60 years ago and a lot of things have be invented and learned since then. However a lot of the fundamental theory has not changed. I played with desk top dyno programs for hours testing this guys theory and they all seemed to prove out. Granted that is not a real engine, and my running computer simulations does not match up to your real world experience. Truthfully I believe you have given great advise here, and I would personally go for more stroke and less rpm.

The guy is set on building a short stroke engine, so I gave him the information I have that might help him.

Some personal observations over the years. I have seen some 289 Ford and 283 Chevy engines eat big blocks alive back in the day. There street manors sucked. In the early seventies we could stroke a 400 sb Cchevy to around 460 cid. Nobody (bar a few mega dollar race teams) could figure a way to get them to breath. It was a waste of money, and we were de-stroking them with a 350 crank and rods.

Today there are great heads everywhere, and strokers are the rage. Before there were good flowing heads, it was a waste of time.

As far as the cam game goes, look at the duration and lift that Sean Highland (hope I spelled that right) wrote in his book on the 4.6 ltr Ford. I think he was under 230 duration at 0.050 lift and a max lift of 0.480" at the valve. With ported 4 valve per cylinder heads, he was making good low end torque and peaking the Hp over 7000 rpm, normally aspirated. This is proof enough for me that you don't need to go radical on the cam if the head flows good. Granted a two valve per cylinder head will likely never compete with the 4 valve per cylinder heads.

[roadrod2000]

I have a HIPO 289 powered Unique FIA car with a 4.27 rear axle ratio and a ford motorsports T5. The camshaft is a solid lifter with .560/.512 I/E lift and 244/254 duration at .050. I just looked at a chart comparing RPMs at MPH for both my setup and the one proposed by XB-60 /Glen (3.07 rear and wide ratio toploader). What I find is that my 2nd, 3rd, and 4th gear are very close to the same (compounded ratio) as Glen’s 1st, 2nd, and 3rd , with that in mind this is what I experience driving the car; 1st gear is too low, I can easily get the car moving by starting in 2nd (starts on a hill might be a challenge though ) 2nd through 4th are well spaced and fun, but my jump from 4th to 5th is too much of an RPM drop, at 55 in 4th I’m at about 3000 rpm’s, the shift to 5th drops me to about 1900 and the engine is not happy there, so driving a winding mountain road is a battle between 4th and 5th . On the freeway at 70 I’m at 2400 rpm’s and that works fine for cruising but ideally I want to raise the rear ratio and drop the overdrive ratio so that 4th to 5th is closer. To summarize; the 3.07 /wide ratio toploader combo would probably work well with my car and for how I drive it, but on that hill I would want a slightly lower 1st.

[xb-60]

Originally Posted by olddog

....you don't need to go radical on the cam if the head flows good....

Good point olddog. There's an article I've come across a couple of times 400 HP 302 ci AFR 165 cc(Stock Cam) about obtaining over 400bhp from a SBF 302 while retaining the stock factory hydraulic roller cam, main changes being heads (to AFR165), by using higher ratio roller rockers, and headers/extractors. Main point is that it uses the stock factory cam. Does that mean that it would retain some manners at the bottom end while delivering at the top end (with the power graph still steep at 6200rpm)?
OK, I've said that my preference is to stay with CI heads for authenticity, but this seems to me to indicate that I could easily stay with a 302
Cheers,
Glen

[Gaz64]

Glen,

That is true up to a point.

A good rule to follow is spend money in the heads, then you can pick the appropriate cam, milder than most would go for.

You can make more reliable power and a better spread of torque with a mild cam (modern grind with less difference between seat to seat & .050 timing) and correctly ported heads,
compared to poor breathing heads and a large cam. You also don't have as much stress in the valvetrain (friction and inertia etc).

The majority of new cars these days have four valve heads for this reason, that is how the factory can offer the flat torque curves the engines have.