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Anyone have any experience with Rev Limiters? It was suggested that I might want to invest in one for my “Big, Big-Jugged Emma” — that it might help keep me from overrunning the RPMs in2nd and 3rd gear…not that I would ever think of doing such a think on purpose…..
Here’s the link to the one that was suggested: http://vwparts.aircooled.net/Pertronix-Digital-Rev-Limiter-Model-600-p/600.htmI’ve used them in the past, and put one on the newly-built engine. I use the less expensive variety — the rev-limiting rotor button.
The one you’re showing is a much nicer alternative, and gracefully limits the revs, whereas the rotor buttons simply shut off all spark — quite abrupt, but still better than engine damage from over-revving…Early FF TDr on 69 VW pan
Slowly coming back from the ashes...Another alternative that was suggested was to just go with a Shift Point light. I assume that the light comes on and shines in your face when you hit a set RPM — and the light would stay on as long as you were exceeding that set RPM point. Using the shift point light in that manner would accomplish both warning when approaching the shift point and warning of reaching high revs — as long as the rev limit works out to be the same rpm as the shift point…??? Don;t know much about this having never had a car on a track — but interested in keeping the engine from eating itself if I become distracted and forget to look at the tach (which I can’t see anyway because it is buried behind the steering wheel out of sight for my “short” eyes — but that’s to be fixed by raising the steering column…a project for another time)
Bottom line — would using a shift point light be a good substitute for a rev limiter?How well it would work as an alternative would depend mainly on the driver…
They’re intended for two totally different uses:1. Shift Light to tell the driver when to optimally shift to keep the engine in its power band2. Rev limiter to prevent mechanical damage from over-revving the engine, such as when you “miss a gear” when shifting…Many dragsters have both and use them quite differently…KentT2014-06-01 13:50:20
Early FF TDr on 69 VW pan
Slowly coming back from the ashes...Ed, that’s a good question. I have no data on that. I have had it rev’d up to 5500 for a short time and it could still have gone higher — but what’s the designed top rpm — ??? How can we tell other than revving it up until it eats itself and then backing down a few hundred rpm…???
I do have the name of the guy who R&R’d that engine in 2008 – I may try to get him to comment on rev limits for a “typical” 2332 that he builds…???Otherwise, any suggestions will be gladly and warmly welcomed.I sent an email to the shop in Dayton OH that last worked on that engine …and it was in 2005…I’ll post info on redline for that engine if I get a response….
That’s why I asked, Jack. If you buy a rev limiter and/or a shift light you ought to know about where the engine is designed to make power, and where it’s over-revving, so you can set it up.
Typically in big VW builds you find these numbers two ways.* Or actually you combine the ways.Way number 1 involves talking to the builder and getting his idea about what your combination of cam, rockers, valves, porting, carbs, exhaust, compression ratio and valve springs is likely to get you. So he might tell you something like “The FK89 and 1.4s usually make for a radical build, but with this much displacement, compression ratio and the light package it’s in, you should see decent drivability right off idle, peak torque around 53-5500, and peak horsepower right around 6500 rpm or so–but don’t spend a lot of time up there.”Way number 2 involves driving the thing and judging by the seat of your pants where the power band is. If you light the car up and put your foot in it and it pulls strong up the revs but falls flat at, say, 5000 RPM, then you know (if the builder told you it was a 6500 rpm beast) that you need to start looking for the problem–fuel starvation, spark arc, maybe the wrong valve springs, etc.I say all that so I can say this: Regardless of what anyone, including the last guy who worked on it, tells you: if the engine runs strong, and wants to rev past 5500, then chances are good it was built to do just that. You should play with it over 5500, over 6000, and even over 6500 a little to “feel” where it wants to peak–and where power starts to fall off. Exceeding that power peak by a few hundred rpm will not toast the engine. (Unless it was put together by monkeys and so destined to fail anyway).Over-revving damage comes when you miss a shift with your foot planted and take to 8500 rpm a motor that’s meant to go no more than, say 6000.Or when, in the heat of anger, you go for 3rd and somehow jam it back into first, so that even when you get off the gas you’ve got the whole car pushing all the parts well above the rev limit.An electronic rev limiter will not prevent that kind of over-rev damage.Anyway, on a street car with a tach, I don’t understand the need or desire for a rev limiter or other device that’s meant to ameliorate operator error. Why not find out where the power peak is, remember that sound and, as a reminder, turn your tachometer so that number is at 12 o’clock? That’s the way my grandma did it and she never had any trouble out-runnin’ the law even with a full load o’ shine.*The third way, of course, is spelled D-Y-N-A-M-O-M-E-T-E-R and used to be out of reach for any without sponsors or a big trust fund. These days, not so much. So that’s an option also.Wow!! Great advice Ed. Now I just have to find a deserted paved landing strip so that I can experiment without any more blue lights coming up behind me to see what I’m doing….
Oh, and I have to wait until I get that SCAT pulley with Sand Seal delivered so that I can try to keep the oil in the engine and not on the engine.Seems that I’ve been spoiled by Emma’s charms — took out Abby (1600cc stock) yesterday and lo and behold, it did not want to kick me back in my seat in 2nd and 3rd gear — and it sounded like a VW??? and the windshield did not fold…go figure!!Hey Jack! Two hours down RT 17
$100 to do a dyno pull & I bet when they see what ya brung they give you one free.That was:
Drew’s Off Road Performance LLC.2610 Bobmeyer Rd.Hamilton, Oh. 45015
The engine was modified by them in 2005….LOOOOOOONG time ago in engine years, I guess — unless the car was sitting for most of that time…???And Ed, that $ 100 spent on a dyno pull may be worth it to settle my mind as to how much power that engine can really put out. But isn’t running an engine that hard on a dyno a risk?Hey all,
I did get an answer back from the engine tuner in Ohio — here;s what he said to my question about top RPM and shift point:Hi,I will conservatively say 5500 RPMS. I asked our engine builder and he said that’s a good place to start. Do you know what type of connecting rods and valve springs you have in the engine? If you have some dual valve springs and I-beam or H-beam rods you can run it up some more.Looking over our records I see a receipt for Steve Hampton for a 2332 engine build from 2005. I am guessing he may have supplied some of the parts as we did not charge him for things like cylinder heads, rods and pistons.Most 2332 engines are pretty torquey. Your power-band will depend on the cam but most stroker engines with small to medium cams see peak toque between 3500 or 4000 RPM and torque will drop off by around 5000 RPM. If you find out what cam is in the engine I can give you some more detail on that.Until you learn the engine more I would not cross 5000 or so RPM when really stomping it. Otherwise during cruising just be easy on it and shift around 3000 RPM.That is pretty neat that you put such a big engine in the car. I bet you will surprise a few people when they see a bug eyed 50’s car screaming down the street. Glad you got your ticked reduced.If you want to drop by some time I am sure we could have our engine builder take a look at the car with you to see what he thinks.Thanks,Austenawesome!
Hot Rod dyno article 2006 on what to expect:http://www.hotrod.com/techarticles/general/hrdp_0607_performance_engine_dyno_testing/
Here’s the innerwebs on the question “Can a dyno pull hurn my engine?”(Those last two are in regard to Harleys & other air-cooled bikes. Worth considering with a VW but, as the Hot Rod article shows, a 300 rpm-per-second power run is going to be over in 20 seconds or so–before the engine would likely overheat…).–must read “doborostang” about half way down the page.You need to get that pesky left Dell sorted out before spending dyno $$, IMO…
Early FF TDr on 69 VW pan
Slowly coming back from the ashes...Kent, you’ve got the right word: pesky. When we took the carb off the car and rebuilt it, I noticed that the o-rings that go around the idle mixture had hardened and cracked, and crumbled…another victim of ethanol. The idle jets pull fuel from a small inaccessible chamber that pieces of the rubber had migrated to. Used air and carb cleaner to flush out and hoped we had gotten it all, but alas – no joy. Did the same a 2nd time. Really runs great for a while. The frustrating thing is that we know exactly what’s wrong. We’ll get it! And most certainly before (if) dyno-ing. Had this carb completely apart, right do an to the mainspring. These carbs really are nicely built except for that chamber at the base of the idle jet not having a clean out plug.
……and speaking of Dyno’s, did anybody see one at Carlisle this year? There was one 2 yrs ago, but I don’t remember it this year or last.
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