Highest-revving SOHC automotive engines?

Like title says.... i'm almost sure there were some old school single slammers that had the bejeezus revved out of them, but i'm struggling to place exactly what they were. I'm guessing German or Italians of some sort?

I know more modern, the Honda D-series can be made to rev, but i don't recall seeing any of them really going past 8000rpms.

I'm looking for 9000-10000rpm 4 cylinder examples. Bonus points for youtube clips for sound.

As a bonus side discussion: Just how import is Rod/Stroke ratio REALLY? Not just in terms of rev capability, but also characteristics of the motor itself?

Could or should?

Either/or.

I'd settle for "could consistently without grenading."

The Ford 427 SOHC was a 9000 RPM'er, at least on the NASCAR banks...

Oops dammit, sorry.... i should have specified "4 cylinder."

In reply to Swank Force One:

LOL, I should have figured that was where you were going! I can tell you that some motors can get there (Ford Lima 2.0/2.3) but only with massive amounts of aftermarket parts. The Porsche 944 2.5L lump went pretty well for the time, but I honestly don't know if they can go that high.

Javelin wrote: In reply to Swank Force One: LOL, I should have figured that was where you were going! I can tell you that some motors can get there (Ford Lima 2.0/2.3) but only with massive amounts of aftermarket parts. The Porsche 944 2.5L lump went pretty well for the time, but I honestly don't know if they can go that high.

We may or may not have found a way to put together an F-series engine with a 1.92 rod/stroke ratio while losing only 0.2 litres or less displacement. Which... sounds like it might be an awful motor that destroys all that is good about the F2, but i disagree.

In reply to Javelin:

Well technically each 4 cylinder bank of the SOHC 427 turned the same RPM as the other...

I'd say go short stroke and small, like 1200 -1300 cc. Suzuki Swift GT, maybe? Many of the larger bike engines are easily capable of that rpm.

bravenrace wrote: In reply to Javelin: Well technically each 4 cylinder bank of the SOHC 427 turned the same RPM as the other...

It's when they didn't that problems happened.

jstein77 wrote: I'd say go short stroke and small, like 1200 -1300 cc. Suzuki Swift GT, maybe? Many of the larger bike engines are easily capable of that rpm.

The Swift GT was DOHC, though...

I'm guessing that most of the motors that did it are going to be 1600cc or smaller, i'm just wondering what those motors were.

Lampredi Fiat/Yugo SOHC could turn to 10K with better valve springs. I can't find the clip I saw a long time ago with a Yugo drag race car that was power shifting at 10,000rpm. Pretty impressive sound.

Of course sport bike motors.

Typically anything with extremely lightweight internals could spin that high since you'll typically run into valve float fairly easily. They are usually lacking in torque as well since larger diameter pistons and longer stroke don't equate to running at high RPM. On top of that, there's whether the engine can flow enough air at those speeds to do anything other than make noise.

Offenhauser... no, that is DOHC.

turboswede wrote: Typically anything with extremely lightweight internals could spin that high since you'll typically run into valve float fairly easily. They are usually lacking in torque as well since larger diameter pistons and longer stroke don't equate to running at high RPM. On top of that, there's whether the engine can flow enough air at those speeds to do anything other than make noise.

True on all counts. Valve float won't/shouldn't be an issue. Making the head breathe enough will be a task, but probably doable.

To delve a little deeper in here, since i'm talking about my favorite piece of crap engine:

I've seen an F2T revved to 7600rpms and it was still doing work, though obviously had fallen off of peak. But this was a 100% stock motor. Mine with a wounded bottom end saw 7000rpms recently with my "Swank Force Special" head and it was pretty terrifying up there, felt NOTHING like stock.

F2T has an 86mm bore, 94mm stroke, rod/stroke ratio of 1.68.

I can build a 2.0 litre destroked motor with a square 86mm bore/stroke, rod/stroke ratio of 1.92. What i'm hedging my bets on is that the head due to its limitations will actually prevent the low end from being so unusable that it can't easily get a 2100lb car moving. The hard part will be getting it to make power way up top where the new "happy" theoretical RPM range will be.

It's all theory at the moment, but there's enough there for me to seriously consider doing it, since i could easily throw together the entire motor for $1000 or less and then start seeing which OEM components will fail first.

The Lampredi is a good lead, i will try to find out more info on that.

The Fiat SOHC is what I was going to say. Great little motor.

If you can take a motor you know, port the head, throw HUGE cams in it and see what happens, I'd say go for it.

z31maniac wrote: If you can take a motor you know, port the head, throw HUGE cams in it and see what happens, I'd say go for it.

Already did that, unfortunately a couple things around the rest of the car prevented me from seeing the results at the Challenge.

I'm reasonably sure i'm sitting on an 8krpm motor barring oiling issues.

Is your engine internally or externally balanced? Both could cause headaches if you aren't having a shop blueprint and balance it all.

Internally. Balancing would happen.

Anything with a cross flow head can probably be made to get there... with a bit of port work you might be able to twist a 2/3TC to over 8000 rpm if you have the right crank

About rod to stroke ratio... the 4AGE with a stroke of 77mm and a rod of 122mm is far from ideal... not bad for a 14,000 rpm capable engine. It is interesting to note that most of the current Atlantic type 4AGEs are now running rods that are 127.5mm long... and running rpms levels of "only" 10,000 to maybe 10,500.

SWO... WHY do you need a 8000+ rpm SOHC engine??

oldeskewltoy wrote: Anything with a cross flow head can probably be made to get there... with a bit of port work you might be able to twist a 2/3TC to over 8000 rpm if you have the right crank About rod to stroke ratio... the 4AGE with a stroke of 77mm and a rod of 122mm is far from ideal... not bad for a 14,000 rpm capable engine. It is interesting to note that most of the current Atlantic type 4AGEs are now running rods that are 127.5mm long... and running rpms levels of "only" 10,000 to maybe 10,500. SWO... WHY do you need a 8000+ rpm SOHC engine??

Why DON'T i need a 8000+rpm SOHC engine?

I'm talking about an 86mm stroke and a 165.5mm rod in this case.

Ben...WTF are you doing? I read 2100lbs... does this involve the 93?

Did SFO just realize that the same amount of torque at a higher RPM equals more power?

hehehehe

Dude, I don't know the specifics of this stuff, but if guys can make big V8s from the 60s go to 10 grand, surely you can grab a motor thirty years more advanced and hit 8 with some work. I'd just try and see.

mndsm wrote: Ben...WTF are you doing? I read 2100lbs... does this involve the 93?

Yep. I'd obviously have to wildly change rear end ratio if this ends up working, unless i want a full-on LSR for whatever reason.

My main concern from a strength aspect at this point is the rods, but the piston speed will be kept in check a bit with the destroke/long rod aspect.

However, the record breaking F2T also broke... seems the #4 rod broke, which is ASTOUNDING to me that the rod went before the piston, since you know... the rod is forged, the piston is NOT.

Luckily, the G6 rods are at least as robust as the F2T units, so it should be strong enough to at least verify proof of concept.

tuna55 wrote: Did SFO just realize that the same amount of torque at a higher RPM equals more power? hehehehe Dude, I don't know the specifics of this stuff, but if guys can make big V8s from the 60s go to 10 grand, surely you can grab a motor thirty years more advanced and hit 8 with some work. I'd just try and see.

Heh, i already knew that, hence the focus on the head i put together for the MX6 currently. The horsepower numbers people put out with these motors is a good 100-150hp too low, in my opinion. Because they're losing torque. I fixed that. (or at least the butt dyno says so, so far.)

I wouldn't call this motor 30 years more advanced. It was outdated as far as i'm concerned by 1980 standards.

But i'm not shooting for 8. I think i could hit 8 and make power WITHOUT destroking.

I'm wanting 9-10k for no real good reason whatsoever. But even if i can't do it, i'm still intrigued by the destroked motor from a power/smoothness aspect. Destroked motors like boost.