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

[xb-60]

Thanks Rick. Interesting stuff. I’ve never heard of using aluminium alloy conrods….how does the strength of the rod compare to a forged alloy steel rod? Their section dims would need to be bigger, surely, and then they lose some of their weight advantage, wouldn’t they?
Agreed, as near to perfect balance as possible is essential for high revs. And don’t forget, I don’t want or need big power. The original FIAs were winning with 380bhp, so 300 to 350 flywheel hp is easily enough (and OK if I find I need more a year down the track, I deal with that at the time). It would seem this thread is already past its use-by date, but what the heck …. so what’s wrong with chasing revs, but not chasing horsepower? Generalising here… what’s the hangup with big horsepower numbers. Is it a geographic thing? So, well and truly established that I’m not after the big horsepower numbers, does that make it easier to spec an engine with good enough manners from 1500rpm to 6500 or 7000? If I use were to use something like Dynatek FI, does that make it simpler?
Cheers,
Glen

[zrayr]

Originally Posted by xb-60

Thanks Rick. Interesting stuff. I’ve never heard of using aluminum alloy conrods….how does the strength of the rod compare to a forged alloy steel rod? ..........."
Cheers,
Glen

not strictly an "auto" example, but vintage Triumph motorcycles, the 650cc & 500cc twins used aluminum connecting rods. So the practice is not unknown. Actually, the bottom cap was steel but the main part of the rod is aluminum.

I have no doubt you will be able to re-create the 289 FIA Cobra to be as original as you want (complete with a 289 engine if's that's your desire). And you will have a blast doing so.

My un-solicited advise is to get it as like the original as possible in every way. Drive it for a while. Then you will know first hand what you want, or need, to change.

Z.

[xb-60]

Originally Posted by zrayr

.... I have no doubt you will be able to re-create the 289 FIA Cobra to be as original as you want (complete with a 289 engine if's that's your desire). And you will have a blast doing so.

My un-solicited advise is to get it as like the original as possible in every way. Drive it for a while. Then you will know first hand what you want, or need, to change.

Z.

Thanks Z. Good advice.
Cheers,
Glen

[Maurice Butler]

Originally Posted by xb-60

Thanks Rick. Interesting stuff. I’ve never heard of using aluminium alloy conrods….how does the strength of the rod compare to a forged alloy steel rod?

they are used extensively in drag racing circles and are life to the number of revolutions they do as they self destruct due to having high rpms, excessive combustion pressures for about 7 or 8 seconds, but the up side is a light rotating assembly accelerates faster, in the lower gear where quite often the limit to the rate of acceleration is the rotating mass in the engine, clutch/torque converter etc

[blykins]

Originally Posted by xb-60

so what’s wrong with chasing revs, but not chasing horsepower? Generalising here… what’s the hangup with big horsepower numbers. Is it a geographic thing? So, well and truly established that I’m not after the big horsepower numbers, does that make it easier to spec an engine with good enough manners from 1500rpm to 6500 or 7000? If I use were to use something like Dynatek FI, does that make it simpler?
Cheers,
Glen

I've never suggested big horsepower numbers to you....I've suggested USABLE numbers to you. There's a huge difference. I didn't suggest a 347 because I wanted you to chase horsepower, I suggested it because it would help add power down low so that you could possibly rev it a little higher.

If you are TRULY after those specs (1500-7000), then you need a modern EFI engine with variable valve timing. You will never have a pushrod 302 with good manners from 1500 to 7000.

If you aim for a 7000 power level, then you will not have any bottom end. Coupled with that 3.07 rear gear, you will not have any stoplight to stoplight racing because it will take you that long to get the thing going, get into a power curve and get through 1st gear.

Glen, have you ever driven a Honda S2000?

[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.

[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

[xb-60]

Originally Posted by blykins

.....If you are TRULY after those specs (1500-7000), then you need a modern EFI engine with variable valve timing. You will never have a pushrod 302 with good manners from 1500 to 7000.

If you aim for a 7000 power level, then you will not have any bottom end. Coupled with that 3.07 rear gear, you will not have any stoplight to stoplight racing because it will take you that long to get the thing going, get into a power curve and get through 1st gear.

Glen, have you ever driven a Honda S2000?

Hi Brent. No, but yes to a Civic with one of those VTEC thingies that rev to the moon, and also considerable miles in a Mazda rotary that had nothing down low, but past that it felt like an electric motor winding up to speed. Could be addictive.
And a V8 with THAT rev range? I remember reading about DL's RCR GT40 from several years ago with - from memory here - a 9.2" deck SBF with an upper limit of around 8000 I think, as well as the ability to drive the kids to the corner shop? OK yes, would have been costly, but what I aspire to is a little less exotic. Brent, I think I have already said that you guys, experts I have absolutely no doubt, have built more engines than I've had hot dinners, but if there's something I think just possibly might be achievable, I shouldn't just rollover as say 'yair, whatever'. If Shelby had said that, we'd all be drivin' them Corvettes now!
Cheers, buddy.
Glen