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Sat Nov 28, 2015 2:56 am

Morning guys,

I'm going to get my trusty 1641 on the dyno, I know the stock filters on the K Dogs are restrictive due to how much the idle changes when I remove them so I was thinking of having them out with just the wire outer screen on to stop gravel and mice getting into the engine... Only for a power run though! Question is, will I get away with just slipping bigger mains in? up to 130's maybe from 125? I understand driveability will suffer but I NEED to make 90 BHP! I've got 2 bets on plus a friend with 84BHP and a guy on VZi who made 88BHP on EFI

1641
Cleaned up stock heads
K dogs
Match ported
3 angle valve seats
Scat c35
SVDA
1 3/8"

8.2:1 CR

Cheers guys :)

Sat Nov 28, 2015 4:25 am

If the idle changes when you remove the airfilters, you have some seriusly clogged up filters!!!
For a dyno run there is no reason to use filters. Also you can remove the "bridge" that holds the filter attachment, which will straighten the flow into the carb.
If thre AFR is good with the 125 mains, I would leave them in w.o. filters, because a lean setting pulls more power. If you do not know anything about that I would go for the ball park and install 130 mains. with that low CR you most likely need to be on about 32 degrees timing to get max power.

That said, I doubt you will hit 90 hp. The Solex main jet sizing is a good indication of how much power the engine makes. I would say mid 80és and 135ish NM torque.

But let us know how it turned out. I love to be proven wrong :D

T

Sat Nov 28, 2015 5:47 am

Its a good engine I'll give it that, the last build I did ended up going in the camper because my Mrs moaned that I had 2 engines for the bug and nothing in the camper... The 78x90.5 went in there and I stuck with the lowly 1641 in the beetle but credit where its due it does drive well... I just wanna get it dyno'd to see what it actually does...

I stuck a pair of period kadron filters on, you know the dull ones with Kadron embossed... I keep saying I'll nip the the shop and see if they've got new elements for em... Haven't done yet though!

I'd have liked to up the CR but the case had already been decked a fraction and with the rest of the combo it mocked up perfect with the stock pushrods so really didn't want to shave any more out to increase it anymore.

It takes 30° vac off... Not a touch more or it hates it! I'm having trouble with my wideband ATM, innovate aren't being particularly helpful either but I would like to get that sorted soon!

Sat Nov 28, 2015 5:51 am

OK - couple things from a guy who has done more than a few dyno runs with Kads on 3 cars and tested them on an additional 2 or 3 other of my own engines plus a buddy's car. Have also done repeated testing on some of the cars after various changes. So I dunno, several dozen runs?

First assuming this is a chassis dyno.

The point of the dyno is to learn what you have, make adjustments to improve performance and leave it alone.

The filters that come with them are not restrictive HOWEVER, Kaddie shack has demonstrated that at higher RPMs the stock mounting method is restrictive because it blocks part of the throat and I believe causes additional turbulence. His fix is simply to use stand offs to raise the cross piece up from the top of the carb. I have never bothered with this mod because my cars are street cars with modest displacement - biggest is 1955.

125 mains are way small - but if the car is kind of happy with that, I would STRONGLY suggest maximizing your dyno time and bring a set of 130s, 132s and possibly 135s. Run it like you have it, filters etc in place. Now pop the filters and look down the carb throats when you are getting above 3000 RPMs and you will see a stream of fuel coming from your accelerator pump nozzles. Its not supposed to do that. Bend the nozzles up about 1/2" and re-aim them. Now do a run and you will see that you all of a sudden got lean in that range since you are no longer siphoning fuel.

Now step up at least to 130 mains and your A/F should be smoother with out funny lean and rich spots. You should have decent numbers. Next go to 132 mains and I suspect that you will show a power increase as well. You can try the 135s, but I suspect power may be down a little.

As far as your final numbers go - (and still assuming a chassis dyno) depending on what correction factor you use, you will probably come out to about 70-75 HP at the crank. And don't forget - dyno numbers and somewhat subjective not totally absolute.

Besides the cam and the 41 cc larger displacement, your combo is almost identical to what we have in my wife's 61 and we get 70 at the crank.

And clean or replace your filters. I have run with and without and have not seen any appreciable difference. Also set your idle mix properly - suspect that is out of whack and you may want to check your synch.

Sat Nov 28, 2015 11:29 am

Good point with the acc pump nozzle. Did´nt think of that.
Yes dyno figures are somewhat subjective, but as long as the numbers are calculated from a known formula, DIN, BHP or even SAE and drivetrain friction is measured the final numbers are reasonably comparable.
We have compared calibrated chassis dyno´s located in Sweden, here in Demark, Germany and the Netherlands. And as long as we are calculating from the same formula and correct for weather conditions we get results on the same result +/- 1,5% That´s reasonably accurate.

T

Sun Nov 29, 2015 6:18 am

The accel pump nozzle is something that I found on EVERY set of Kadrons I have installed over the last 6 or 7 years. Not sure when the issue started, but what they do is have them too far down the venturi and the vacuum draws gas from the bowl at higher RPMs. I found that when dynoing a drivable pan. Did not understand how I was going from lean to fat like I was. Bent them up and problem solved. The nozzle now is about even with the top of the center ring. Then went back to the first car I put Kads on and saw the same thing. Fixed that. So now I just reposition the nozzle before installing any more.

This also explains why you see people with a similar combination running anywhere from a 127 to a 135 main. We are running 132s in our engine that is similar to yours.

For curiosity sake, what is the total correction factor you are using to calculate crank HP? Mine is 20%

Sun Nov 29, 2015 8:38 am

Yes I know the problem, just didnt think of it.
We do not use a correction factor on drivetrain loss. We measure it and the software calculates flywheel power.
T

Sun Nov 29, 2015 8:39 am

Yes I know the problem, just didnt think of it.
We do not use a correction factor on drivetrain loss. We measure it and the software calculates flywheel power.
T

Sun Nov 29, 2015 11:10 pm

Hi guys, don't worry about the pump jets, these carbs are setup well. I've vapour blasted them, rebushed the throttle bodies, rebuild kits and set up the squirt.

I tuned them a while ago using a wideband in the exhaust, got good mileage and drive nice but a) that was for mileage (leaning out the cruise AFR) and b) on an engine that was maybe still bit new/tight...

Seeing as the wideband isn't playing ball I've rejetted them on the butt dyno, ended up going to 130 mains and 52.5 idles. Its definitely pulling better now, mileage through the floor though no doubt :DD
135 is def gonna be too big but I'd like to source some jet drills and open up a spare pair of 130s to 132.5... Maybe that'd help.

Gotta get that compression up too, the engine has to come out as its developed a weeping case seam at the front or the flywheel seal is leaking... Needs a new clutch too!

What would be a safe CR to jump to? Sea level? Can run on 98 RON if needs be which I think is around 93 octane...

Mon Nov 30, 2015 2:26 am

9-1 on 95 octane. About 9-5-1 on 98 octane. Havent played that much with the C35. I kinda skipped that and went to other grinds...
OK with the jetting. - Sounds more normal too.

T

Mon Nov 30, 2015 3:42 am

Octane or RON?
Will the jetting change much with higher CR? May need some new jets ordering.

Mon Nov 30, 2015 7:02 am

Euro fuel. You are in the UK arent ya :wink:
The closer to "perfect" CR you are, the more efficient the engine is running. So unless you have a rather large deck height you will most likely notice that the engine wants less fuel on the idle circuit and a tad more on the main circuit.

T

Mon Nov 30, 2015 2:14 pm

Cool, I'll aim for 9 and a bit:1 then.

Yup UK. How come you've never bothered with the c35 T? Anything in particular you don't like the look of?

Mon Nov 30, 2015 3:38 pm

andk5591 wrote: The accel pump nozzle is something that I found on EVERY set of Kadrons I have installed

Me too...
Even after you 'fix' them, they go back to doing it again.

Only solution seems to be to beat them flat with a brick!

Mon Nov 30, 2015 4:00 pm

I don't see 90hp with that combo. Add 1.25 rockers and 36-40mm dual 2 barrels, now you've got a shot.

Mon Nov 30, 2015 11:10 pm

I think 1.25:1 would be too much for stock pushrods and HD singles. I'm not really into spending a great deal more on it either tbh. Its a good strong engine that has taken abuse well, a bit more CR and a new clutch disc and we'll see what it can do. No great shakes if its only 80bhp I guess... Would be nice to have more though!

Premium fuel and try again for 32* advance :D

Tue Dec 01, 2015 11:46 am

UK Luke 72 wrote: Cool, I'll aim for 9 and a bit:1 then.

Yup UK. How come you've never bothered with the c35 T? Anything in particular you don't like the look of?
Hello.
The C35 just don´t do what "I" expected it to. So I found some other grinds that suited my expectations.
The C45 on the other hand is a great cam for its range.

Actually the 1,25 rocker solution on intake alone would wake the engine up a bit if you raise the CR to 9-1. But yes You will need better PR´s.

T

Wed Dec 02, 2015 4:03 am

Drop a c45 in and 10:1 then I'll make my 90bhp? :D

Wed Dec 02, 2015 4:39 am

Definitely!
But I think you will be better of with just optimizing what you have.

Wed Dec 02, 2015 4:59 am

Yeah I will.
Clean it up,
Reseal the case,
Increase CR,
Check out internals
Rebuild,
Dyno

It's only a stopgap until the next engine...

Thanks as always T :)