dyno test this morn -

I have built a new motor for my bug and ran it on a Dyno Dynamics dyno this morning……only about 85hp at the wheels approx 6000rpm ( 135km/hr indicated by the dyno, top gear std ratio….unfortunately the dyno does not output power vs engine RPM)

My motor;
*2276cc, 82 x 94mm
*Engle FK10 cam, 1.4 ratios
*twin 48 dellortos (40mm chokes, 70 idles and 180 mains)
*044 heads, home wedge port, 42 x 37mm valves, 3 angle grind, opened up and cleared exhaust ports, CCd, unshrouded etc… CB tall manifolds match ported.
* A1 low down header 1 5/8”, custom 2.5” hideaway exhaust with straight thru magnaflow muffler
* comp ratio 9.3 :1
* straight cut cam gears
* 12lb flywheel
*5.4” scat I beams


The motor drives really well, the cam comes in strongly at about 3000 – 3500RPM and pulls well up to 6000RPM (I haven’t taken it further yet). The thing is, it feels very powerful??!!

The exhaust probe indicated I am leaning out at higher RPMs (up to about 17)

What do you think about the low hp reading?

Cheers

17:1 is scarey lean.
First make sure your fuel pump and lines are adequate to supply the system with enough volume.



Also, if that is correct you may have to reduce your air correction jet a bit. (or a lot!)
That main is borderline big depending on your altitude above sea level,
and so a large air may have been installed to compensate.
This in turn may cause your lean-ness up high.

CB always used to recommend a main size that is 4.2 times the size of the venturi. (and start with a 180 air corrector).
I would choose something in the 4x to 4.2x and then tune with the air corrector.

Most engines with cams like yours should be well above 100 hp if the heads are up to the job.

These are just rules of thumb, so details may vary.

Prolly should of tried to dyno it in 3rd.

I wonder about that too, a Vw in high gear may read a lower hp reading at the wheel because of the loss thru gearing. Most v8 cars are 1 to 1 ( TRANS )in high gear, if yours is .89 your readings should be off. I have never tried it ,but would be interesting to see if or how much differance it would make in third. Mike

you shouldnt be worring about the HP reading it will and does vary from machine to machine and day to day

the dyno is a stationary tuning tool for tuning the engine under load

sure they give a reading but its not really important

If you make any more changes to the engine take it back to the same place so you have a comparrision to use to see if you have made any improvements

As per Dave i would be worried about the 17 to 1 fuel reading you may burn a head very easy better to be slightly rich around 13 or so

thanks for the replies.

I am worried about the lean-out also. FYI, the motor is in an oval with stock fuel line (reserve tap removed). I have mounted a whopping big carter pump under the tank and a holley reg before the carbs. I have adjusted fuel pressure to 2.5psi. Dave, when you mentioned about making sure I am getting enough fuel into the engine....what volume / minute should I get out of the regulator (i.e. for the two carbs). Also, originally I had 3.0mm needle and seats for the float valves, which were leaking. I could only get 2.25 replacments - could this also be a cause of the hight RPM lean out.(maybe I ould drill them out??)

once again thanks for the help.

deluxe hunter wrote:thanks for the replies.

I am worried about the lean-out also. FYI, the motor is in an oval with stock fuel line (reserve tap removed). I have mounted a whopping big carter pump under the tank and a holley reg before the carbs. I have adjusted fuel pressure to 2.5psi. Dave, when you mentioned about making sure I am getting enough fuel into the engine....what volume / minute should I get out of the regulator (i.e. for the two carbs). Also, originally I had 3.0mm needle and seats for the float valves, which were leaking. I could only get 2.25 replacments - could this also be a cause of the hight RPM lean out.(maybe I ould drill them out??)

once again thanks for the help.

CHANGE YOUR FUEL LINE CHANGE YOUR FUEL LINECHANGE YOUR FUEL LINECHANGE YOUR FUEL LINECHANGE YOUR FUEL LINECHANGE YOUR FUEL LINE CHANGE YOUR FUEL LINEVVCHANGE YOUR FUEL LINE

did you hear that?!

no way will a standard line feed your engine

The stock fuel line was too small for my 1915. The heads showed signs of slight over-heating.

I replaced it with 8mm rubber fuel hose and the difference was AMAZING.

Not sure about pumping pressures and volumes, but the first thing I'd be doing is putting in large fuel hose.

yep CHANGE THE fuel line 4 SURE

minimum should be 8mm

the stock fuel line used to feed a 122 main in a 36Hp engine now your trying to feed 4 x 180 mains thats not on

I get the message - thanks. I will change to an 8mm steel line.

I figured that since the std 36hp pump was sucking fuel through the line this would be the limiting factor (cavitation etc...) So fitting a high pressure/ high volume carter pump under the tank, I figured I could simply just blast enough fuel through?? It sure seems to come through in a hurry.

Anyone have an idea of the required flow rate of fuel to the "T" piece?

I will check my flow rate before and after fitting the new line and let you know the difference.

Also, any feedback on the 225 float valves ?

Dude,

8mm line
2.5 needle valves
4-4.5 psi past the reg
make sure the needle valves don't leak with the engine off and the pump running.
try to run as much fuel pressure as you possibly can without problems.
Remember that pressure through a small line does not = volume and the bowl will still empty.
8mm lines as a minimum.

That engine should be well over 100hp mark, but don't stress because it might be the dyno.
Sometimes with the less powerful cars you need to ramp them in 3rd.

dragvw2180 wrote:I wonder about that too, a Vw in high gear may read a lower hp reading at the wheel because of the loss thru gearing. Most v8 cars are 1 to 1 ( TRANS )in high gear, if yours is .89 your readings should be off. I have never tried it ,but would be interesting to see if or how much differance it would make in third. Mike

your car would read less in third Mike.

power is power is power. The only difference would be through different pumping losses and drag via the different gearsets. ie: Not much...

load changes and speed test is what changes that changes the power figure.

well I have just gone out and bought some 3/8" bore hydraulic tube....reckon this should flow ok (going from one extreme to the other!!).

I will measure flow rates out of the reg (set at the same pressure) for the stock set-up and with the ginormous steel fuel line for interest sake....will keep you guys posted.

another question - can I simply drill the orifice a larger diameter in the float valve seat. The way I see it, this will reduce the seat area and maybe cause me some grief.

Sonds like some good advice there.
I personally would have recommended 1/2" OD tube, and what you have chosen is it!

My tube car used 1.25" OD (31.75mm) stainless tube for the supply line...no such thing as over kill!!

Worst thing that can happen is your tank volume will effectively be enlarged😀.
Mine added 2 lt to my volume!


There are a few rules of thumb I use for methanol, but I would have to convert them over to petrol use,
but Nicks advice covers everything anyhow.

But I would not start drilling those deals out...keep things "off the shelf" where you can.

dangerous wrote:But I would not start drilling those deals out...keep things "off the shelf" where you can.

Yep buy some nice new ones that will seal, it will save you time and money in the long run.

well I have just gone out and bought some 3/8" bore hydraulic tube....reckon this should flow ok (going from one extreme to the other!!).

The other item to remember is the actual outlet from the fuel tank

Its no good fitting u beaut fuel line if you still have the 1/8 inch outlet

I used 1/2 inch staino on my fuel injection tank outlet to the fuel pump so its an easy drag out of the tank

Hey Davo thats a massive fuel line I LIKE IT

in the Vintage Drag car we used 1 inch tank outlet to fule pump and the pump will go at 20 liters per minute

On the fuel pressure - 2.5 - 3 is all dells will hold in my experience. I spent hours with float levels and fuel pressure on my 48s.

Jetting is likely to be pretty square compared to idfs. I had 48 dells (non tri jet) on my 2276 and ended up with 175 mains and 180 airs, 65 idles. (K8 9.5:1). Tri jet dells will be closer to 200 airs

now the next question - anyone have any clever / neat ideas about how and where to run the steel fuel line. Being 1/2" OD i reckon it would be a pig to run down the tunnel. Under the car and I reckon it might pick up too much heat from the road over summer??

run your line inside the tunnel much safer just make sure you solid mount it inside and test for leaks dont do what the hippies do and run it loose under the pan. Dave 2322mm long fuel line?

deluxe hunter wrote:now the next question - anyone have any clever / neat ideas about how and where to run the steel fuel line. Being 1/2" OD i reckon it would be a pig to run down the tunnel. Under the car and I reckon it might pick up too much heat from the road over summer??

yeah properly mounted/fixed inside the tube would be best, but difficult especially with a body in place. Next best thing but a grey area legally would be down the passenger side floor next to the tunnel, once again, properly fixed with clamps etc etc

Ive seen line run through the tunnel, heater channel, and the lip between pan and sill on the outside (stainless would be best).
I ran a 3/8 steel line through the tunnel with the body on. Prick of a job but doable. Cut an access hole in the tunnel in front of the pedals and it makes it easier. I managed to secure it in the rear through the gear linkage access and at the front through the access I cut. Used some 3/8 rubber hose split and fed that over the steel line to stop any annoying rattles.

I did mine like this! It is bundy tubing and is - 6. As above I have also slipped rubber hose over the top to stop rattling.





T54

I have a file from a few guys both here and in the states showing how to do the procedure.

shoot me your email address and I'll send it to you.

regards Craig

Out of interest (sorry to get off track), has anyone done back to back dyno comparisons keeping all variables the same (engine combo/jetting/etc etc) to determine the difference in RWHP figures?

I hear a lot about the variations in dyno figures which I am sure is true, but haven't heard of the variation in actual figures to date - would be really interested to hear from you guys with more experience than me!

sorry to hijack deluxe hunter - thought it could be relevant to the thread though.
Alan 👍

I cant say I have any experience with Dyno's, though I do remember reading in a ZOOM mag once, where they did a comparison on a fair few Dyno's and there was quite a varience accross the different ones. It pretty much said some will read High some Low... If tuning it pretty much said always go back to the same one...

But I guess if you use the same Dyno all the time for your tuning this is the best, I guess they are tool rather then giving the exact power. I have heard some ricers will go to one dyno just to get a big hp readout...

At least Dyno shootouts are only ever done on the one dyno...

I guess its a liitle black art, Like VW's 😂

The Dyno run aretoo expensive to go back to back for data purposes

old speedway modified 458 hp at 5800rpm two weeks later 428hp same revs same sorta day was 10 years ago thou and am streching the memory on the facts but was with a top engine builder on the gold coast and he had no answers for us only answer we could cum up with was dyno differences it was a eddy brake chassis dyno if anyone cares!

About 2 years ago I went to Custom Bugs and Busses and then a guy on the central coast. I think both machines were dyno dynamics. There was only a 88 to 89 horsepower variance and that could be due to a slight change in ingnition timing.

Before and after that I'd used Silverwater Automotive Service and their readings seemed right. In the early days I started with 76hp with some badly shrouded big valves. Then in the last year or so I got 96hp due to better flowing heads and a bit more cam duration with the same CR. Then 99 thanks to a 3 angle valve job and a bit more timing.

Using the Warwick Weekend 2006 vs 2007 to verify the 3 extra horsepower and perhaps another 1.5 from a power pulley, it was good for another 2mph (70mph vs 72mph)and 2 tenths over the 1/8th (9.7 vs 9.5).

God I crap on some times.

CT

All good info CT - thanks for sharing it!

I have had back to back figures on a dyno. An extra 20 kw that was not real.

The dyno measures the amount of resistance your car can push against at a certain speed.
So depending on the calibration figures will vary. You can "FOOL" the dyno into being a happy dyno, but what's the point when it does not translate to the track.
Just do your mixtures so it is safe, and the richen it up slightly to be very safe, you will loose a few hp but the engine will last longer.
The real truth of power is the mph you run over the quarter. (power to weight) And don't worry even if it wheel spins the mph will be up by a few.

Hi

This is off subject but relates dyno power out put figures. Dyno dynamics did a test on power loss through dynos. They used a 6 cyl Falcon, they removed the transmission, did a power run, then hooked up the transmission, then hooked up the diff through a hub dyno. In all cases they had an identical power figure.

The power output can vary depending on how hard the car is pulled down on the dyno, tyre pressures, allowing the tyre to roll up on the front roller etc so lots of variables.

Most Dyno Dynamics operators have an automatic feature to adjust for barometric pressure, ambient temp throughout the day. Some devious operators will alter these figures and the dyno software will compensate usually giving a higher reading. So look at the green writing on peoples dyno charts that they put on the web, there has been fudging going to get a high figure. At sea level you should see a (BP) barometric pressure of around 101 kpa, a little less at higher altitudes also the (AT) ambient temp and (IT) inlet temp should be a realistic figure for the location and time of year.

Steve

vw54 wrote:The Dyno run aretoo expensive to go back to back for data purposes

Not if you know someone who has one and you are good friends with them!!! One of my other cars(Corolla Sportivo) has done something like 50 odd power runs on CES' dyno for development work and to benchmark all the mods etc I made to the car. I started with 96kw(128.74hp) and finished with 121kw(162.26hp) The seat of your pants dyno doesn't always tell the truth and a dyno tune for adjusting things like mixtures,timing etc is the only way to go. You change your exhaust system and watch the mixtures change to the point where you could advance the timingr couple of degrees and gain more power.

If you are spending big $$$ on building an engine then why not spend on setting it up properly to avoid what could end up being costly in the long run.

Just make sure that when you find the dyno tuner of your choice keep going back to them otherwise you will go crazy with the insane differences between dyno's.

My brother's Type 3 will spend approximately 2 weeks at the tuners as they want it for that long to make sure it has the best tune they can put into it without jepordising hurting it.

"""" Not if you know someone who has one and you are good friends with them!!! """


YEs that would help

RESULTS FROM FUEL FLOW TESTS.....

Before I swapped out fuel line last week I did a comparison test of the fuel flow rate to one of the carbs (i.e. line pulled off one of the carbs and put into a bottle).

Stock '56 bug fuel line with carter electric pump under the tank and a FI filter after the pump 1L in 36 sec

as above but with 3/8" bore steel tube as fuel line........1L in 32 sec !!!!

Not much difference - but hey its done now.

After doing this and a few other minor tuning tweaks and upping the fuel pressure to 3psi, I went off to the country drags (1/8 mile). My best time on the air strip was 9.28s....enough to be the fastest street reg car there then I drove 200km home.

thanks to all who gave me feedback - really appreciated

Deluxe Hunter, now you have the big pump and fuel line out of the tank don't forget to make the breather pipe from the filler nozzle a bit bigger to allow the air into the tank or you will create a vaccum in there under load and that will cause starvation too. 👍

crazy col here just to throw a spanner in the works my bug at warrick 2300cc eng 48idas std fuel system shifting at 6200rpm 8.44@89mph!And according to wallace racing it made 135 ish hp at the wheels.