RED LINE LIMITS

Ah, Grasshopper........it depends.

If the motor is truly stock, with stock cam, push rods and valve springs, then even with the dual carbs it'll be all done (no increased revs) shortly after 5,000

If you have a reproduction 356 tachometer, then it should have your redline starting at 5,200 rpm.  I would use that as an absolute top limit for your engine.

It is a pushrod engine, not an overhead cam engine, so it will never rev as high as an OHC engine, but shifting at 3,750-4,000 should not be a problem and it's OK to run all day at 3,500-3,750.  

Depending on your suspension, traveling at that speed might be anxiety-causing, and a stock engine will die out a bit on longer hills, but the revs shouldn't hurt it Below 4K.

I guess a good rule of thumb on a stock motor would be to shift comfortably between 3,500 and 4K to keep the engine revs high enough to provide optimal cooling - Remember;  This is an air cooled engine!

This help?

... I will rise calmly, ... and brush the indignity off my trousers.

Thanks, so much! Yeah, this helped tremendously - I'll make sure to treat the motor well and not get too rev happy.

For a completely stock engine, you weren't going to gain much power-wise by revving past about 4000 anyway. And around 5500 you could start compromising the bearing saddles due to the non-counterweighted crank. Stock valve springs will tend to lose control around that point too. If it were me, I'd still be shifting before 4500-5000, and probably more like 4000 routinely, with stock mechanicals even if it wants to rev higher with the new carbs. For comparison, you will hit 100mph at around 4700 rpm with the common stock gear ratios.

Now with a counterweighted crank or even a well dynamically-balanced stock crank and better valve springs and pushrods you could run it in the 7500-8500 range, assuming your intake, heads, and exhaust could handle it. But that's a complete rebuild with better parts throughout.

Gordon and Justin have covered most of it-

Most of the time, shift at 3,000-4,000 rpm. VW motors generally don't like to be lugged; they're small motors that don't develop a lot of power in the lower rpms' (the fan isn't moving fast enough to cool the motor when you're foot's into it), so keep the revs above about 2,000rpm when just toodling around town. I know it will go to 5,000rpm easily (especially in the lower gears) but with the stock cam and stock rockers power will peak at about 4,500rpm. On the highway keep the engine above about 2800rpm and (as long as oil temp stays reasonable) 3500rpm is no problem. And as long as it stays cool, 4,000 rpm for short stints won't kill it.

Stock VW motors are undercarbed, so the 34's are a great addition. What does the engine have for exhaust? A 1 3/8" header and 1.4 rockers will be a great addition; bottom end power won't be compromised and power will peak at 5,000rpm (instead of 4500) with a good hp and torque increase. Have a look here- http://kaddieshack.com/1600dynoresults.html

Hope this helps. Al  

air cooled??? that has no affect on the rpm.

  spin it up as high as your wallet can afford. build big and you dont have to spin it so high to get more power. but it will still spin extra high rpm.

Explain??

I think Mark is talking in general. Sustained highway rpm in an aircooled car must have the right cooling and rpm and load.

RPM, severely modified/balanced engine, 6500 is a good figure. Even though the valvetrain can handle 7500 or more, IMHO more than 6500 will pound the case out.

Stock, these guys above have totally nailed it, 5K max, 4K or so to shift most of the time. Have fun, and if you need more, build a new motor or have one built.

I have some balancing, a counterweighted crank and dual valve springs.

Is 6000 reasonable?

It pulls strong to there.

I'm just concerned that Mark's statement will be taken out of context by someone that doesn't know the in's and outs of VW aircooled engines. Lower rpm's around town (think lower gears and light loads so the engine isn't developing a lot of heat) works if one is in tune with his car. In a situation (in any gear) where you're lugging (lower rpm's) it at full (or near full) throttle and the engine starts making more heat than it can get rid of pretty quickly. Do that on a regular basis and it won't last nearly as long as you're expecting.

And Danny, if the crankshaft is properly counterweighted and everything is balanced right, rpm's will only be limited by the components. If the carbs, heads, cam/valve train and exhaust are all suited to run to 7500rpm then (as long as the compression is right for the combo) I don't think it will kill the case any faster than a motor that peaks 1,000rpm earlier. The extra rpm's will be harder on other parts (pistons and cylinders, heads and valve train) but I think the case will survive. But you've given me a question for someone local that builds some of the faster/higher output motors around here....

Then that's reasonable. You won't be able to notice it in 1st or 2nd, but if you go through the rpm's in 3rd gear you should feel where it "peaks. It will probably rev 500rpm (or even more) higher, but you're not doing the engine any favors by taking it much past it's peak. 

I hear you Al, and agree with you. You certainly can't drive these cars without some kind of sense. But that comes from paying attention to the sounds and listening to the motor. Some guys have it and some don't.

I'll give you an example. I was following my daughter around a go-cart track when she was 12. It was her first time driving. My son and I were in a 2 seater. I never taught her, but she was driving the racing line and passing people cleanly. Braking when she should and gassing it as soon as she could. I was very proud! Some things you just can't teach.

You're right; some have it and some don't, and it sounds like your daughter has it. She must be pretty good.

 You know Danny, guys who work on their cars and have a good idea how all the parts fit together and work usually have a better feel of how the car is running, compared to the people that just jump in it, drive, and leave the maintenance to someone else. I have also known guys that did a fair bit of their own work and really couldn't tell when things changed, and met guys that left almost all work to a shop and were very in tune with how it was running. To quote the late Bob Hoover; "Listen to what the engine has to say. It won't take your money and it is incapable of lying. All you have to do is learn to speak it's language". Sometimes all it takes is noticing a slight change of pitch; you look down and the engine is laboring just a bit more, and the oil (and maybe the head temp as well if you've got the gauge) is getting a little hot. Back off a couple hundred rpm's and the temp stays at a more manageable level. Or you get in the car, start it up and notice a little more valve clatter than usual; an inspection finds a couple of rocker side shims wearing, a pushrod tip pounding in more than the others or a broken adjuster...

One thing I really enjoy here is reading about people (who formerly though they were "non-mechanical") starting to do their own maintenance. It starts with an oil change, progresses to adjusting valves, and a while later they're cleaning idle jets and adjusting their dual carbs. If more guys did their own work we probably wouldn't see so many low mileage cars for sale, where guys found the reality of aircooled Speedster ownership (spending way more time at the mechanic's than a newer car) wasn't quite the same as the dream- roaring around with the top down, wind in the hair (or across the scalp for some of us), any time the mood (or weather) beckoned.

Have you read the book "Zen And The Art Of Motorcycle Maintenance"? As a much younger man I found it a little weird, but stuck with it to the end. I could be about a trip across the country in a Speedster powered by a high performance VW...

And now I've been rambling waay too long. Al

PS- a couple of things: the Bob Hoover bit is my "quote of the day". And you made a very good point ealier- "6500 is a good figure". With proper maintenance (and a good ear, which obviously you must have) a motor with that powerband can last many, many miles (and yes, you are a great example). Power to 7500 would be more fun, but would take way more work to keep on the road, it's not a cross state or country driver and it not going to last nearly as long...

it dosent matter if you are liquid cooled or air cooled air still cools the liquid(unless it's a boat and is cooled by seawater).If your cooling system isant up to the task on either you have a problem. just like no oil how many rpm will it do??untill it comes appart?or starts to damage something? the air cooling has nothing to do with it. it's the perameters of the engine and the pocket of the one paying for the parts& labor.

  I have seen very few acvw engines with a good cooling system, properly sealed. there are many mods that can be done to better the cooling system.even stuff inside the engine to combat heet.

 and all the parts need to be up to the task asked of them. I routinely take my motor north of the 6500~7000 figure.and do maintainance once a year,daily driver,stroker,play in it whenever it's driven,and other than my unfinished racecar&unfinished 356 it is the only car I own. So in short, it's kinda like I said, how much can your wallet afford,and can you fix it,make it so it's up to the task.Ive been building engines since I was about 6,racing around since about then too. perfessional engine builder/machinest for more than half my life.as far as spelling I can do that to....,but miss spelling kinda weeds out the ones that cant comprehend what is being said/discused but gives them something to converse about anyway.yes it's professional...or was that profesional?profishenall?professionell?ok I fess up some just escape me at times.and eyeballs that dont see worth a poop on this thingy and fingers dont listen either.

   But to summ it up dont lug the motor& don't ask more of it than it is capable of giving.if you want a new hiperformance engine than just go out and kill the one you have.....then tell the wife..it just blew up....gotta build a new one... but it happened after I got you these Roses!!!

Thanks Al. You are so right about listening. This is my first car/engine with multi-carbs. It taught me to listen. I also enjoy when people learn to do their own maintenance. I think that is why I enjoy this little car so much. I think if you don't work on it a little you are missing out.

6500 is a good figure for my motor, and btw it is 500 past peak, just like 5000 is 500 past peak on a stocker. I'm sure I could flog mine up to 7500, I was told the valvetrain can handle it, especially in first and second it would do it easily. But really what's the point once peak is reached? I know there are situations where the gearing and a certain corner could be taken faster if you could over-rev and not shift. But it is a street car not a track car, so compromises have to be made. My motor is a great motor, but do you still think it would be alive at 32,000 miles if I shifted at 7500 or 8000? I shift out of third into fourth at 95 mph, how fast do you want/need to go? 

Yeah, Danny; you have a fun combo! An over 2 liter with an Engle FK8 (or anything similar) and the carbs, heads and exhaust to make it all work is popular for a reason. If you were shifting at anything above 6500 when playing you wouldn't be going any faster, and the wear that happens to the heads when using the higher 1,000 (or more) rpm's is waaay more. The amount of maintenance a motor needs as the rpm's goes up is not linear; it's more like a bell curve. Have your heads been off yet? If your motor had a powerband to 7500 or 8,000rpm they'd probably be ready to come off for the 2nd (or even maybe 3rd if using all that power a lot) time.

A motor with a powerband/redline up to about 6,000rpm can have a near stock maintenance schedule and life (remembering that even stock VW heads should come off once during an engine's 100,000 mile life). If the redline is 6500-7,000 then they may need attention another time or 2. If the powerband goes even higher, the motor is pretty high strung and definitely not a high mileage "driver". Guys with powerplants like this will have the heads off (and who knows what else) every year or 2, depending on mileage. These quite often are cars only driven around town (to club meetings and the burger hang-out) on Friday and Saturday nights; yes, they're among the fastest things in the neighborhood (and respected by the local V8 and ricer crowds) but they're not making the 300 mile ride to Grandma's on Sunday.

Heads were only off once, back in 2008 when I pulled the motor to do the crankfire ignition machine work. At the same time I added a set of .010" shims to drop the CR a touch to 9.8:1. That was around 10K on the motor, whole time @6500 redline. They looked fine to me, seats and guides in good shape. Maybe next winter for heads and jugs or around 40K listen for valve noise and do another compression check. I'll do a compression check this spring so I have a recent baseline. Really though with the heads off not a bad idea to split the case and see what the bearings, cam, and lifters look like.

I fired the Spyder up today, I never had a chance to put Stabil in it this fall. I warmed the garage in the sun today with clear plastic over the overhead door. Amazing how good the sun is at heating the south-facing garage! It took a long while to crank, so long the oil light went out. Once it did fire I kept it at 1500 for about 15 minutes. Thankfully I have a hand throttle otherwise that would be a real PIA. I took about 25 minutes before it would hold a 900 idle without hand throttle. Stabil all worked through though so that's a good thing. Wish I could take her out, she runs so sweet. But the roads are very messy around here, so no thanks.

This year I'm going to put the 911 mill together. What is nice about that is it isn't hard to remove the rockers so the valve springs don't get ruined from sitting. Anyway, now I'm rambling so apologies....

We didn't notice any rambling......