The Cal-look Lounge

how much difference does it make ?? as both the other bugs took theirs off in the pit lane  ??? :)

I´ve seen 12-14hp on several occasions.

I've heard figures around 7bhp :-\ :)

App. 17 hp ( Porsche fan/type 4)..Mr.Kirketerps "Black Bulldog"...Dynocharts here :


http://griebel.blogspot.com/2009_04_01_archive.html

My PB was a 17.1 with my 1776cc powered bay

@ Gardermoen I took the van belt off for the first time and ran two 16.7's

It makes a BIG Difference!

Just to clarify, these figures are for type1 with conventional cooling/fan/generator.

Airspeed on this forum, noticed 15hp on the dyno.

Looks like my belt is coming off next time I run the Manx then  ;)

I'd say 10 to 30 hp, depending on the max rpm of your engine! :'(

blimey  :o and how long will it be safe running i mean after the run do you put it on as soon as you get off the track or after a steady run back to pits?
sorry for all the questions ill be asking but im new to this drag racing lark and i know nothing about engines  :-[ so im learning as i go

Take it off in the fire up road and refit on the return road as soon as you have finished your run. Bernie

I saw 20whp difference on my 2221 IDA on a dynapack dyno.
So yes it makes a difference!

Yes! ... Take it off in the lanes while waiting, then resecure as soon as you've departed the track. Engine cools off abit on the return to the pits.

Fresh one (last weekend)
1776ccm 90HP (141NM) did 15.730 @ 133.41 kmph
than the fan belt off:
15,263 @ 137.34 kmph
15,201 @ 137.24 kmph
on radials full weight full interior beetle.
I use BMD system so its easy.
here is a good one for V-belt guys :D http://www.joemonster.org/filmy/18673/Jak_wymienic_pasek_klinowy_w_kilka_sekund_

Not likely.  Some VW engines don't even make 30hp.

That's why there's a range dependent on RPM!

3 tenths and  2.8 -3  mph in the 1/4 mile  , and 2 tenths , and 1.8 -2 mph in the 1/8 mile is what I have noticed. by taking the belt off.   

Kevin

Which crankshaft pulley diameter is considered to be the reference for these observed figures?

 I used a stock size pulley

Kevin

A few years back my 9.5 comp. 2332 fk89 1/34 exh made 191 hp w/o belt and stinger tailpipe, with belt and muff it cost me over 30 hp. (at berg's)Don't have the dyno sheet, but mark v. from the bergs will probably remember the exact amount, maybe he can even look as my dyno sheet as it was on the bottom of stack on dyno sheet clipbpoard.Mark is one smart vw guy. He remarked the higher the rpm motor the larger the loss..P.S. I immediatley pulled the 89 out and put in a k10. Not really to his liking..lost only a couple of hp,189, but I had the 48 ida's profiled/flow improvement at same time of cam change..I liked the k10. now same heads on 2442 with fk46. 181 hp at 4600 elevation.W/belt and muff. No street time on motor yet.gab-fab at work...bill

That funny, You dont have a muffler, Yet.

funny danny, dyno time was with ken taber's 1 3/4 exh and same muffler you will be using... get to work...$$$. bill

Even on the smallest motor the belt makes a massive difference - my 1641 motor in my Ghia (stock bar single QP, 009 and blue coil) ran 19.2 with the belt, pulled the belt and instantly dropped to 18.6. Twin carbs and dual QPs got it down to 18.0 - never ran it with the belt on then! My 1584 motor in my chop top ran 17.0 with the belt, 16.4 without. Closer gears and slicks got it down to 15.7's.
So I work on gaiing up to 6/10ths of a second just by dropping the belt.

This is really good ... http://www.joemonster.org/filmy/18673/Jak_wymienic_pasek_klinowy_w_kilka_sekund_

fook that! lol

never could test this or certainly attest this, but with the type3 the fan isn't as removeble as with a type1, but on the dyno it made 115hp and similar engines reached around 130 hp without belt on type1 engines.

the engine will respond a lot faster/snappier without the fan on a type3, not sure if that drag is also felt the same amount with a belt, but it sure sounded a lot more fun without the type3 fan. on the break in the fan was not mounted and a small powerpulley was used and it revved really nice, afterwards you heard the engine picking up much slower.

so i think 15 hp (probally more) can be lost with a type3 cooling. if someone wants to know.

A graph of back to back belt-on, belt-off dyno tests.
2110cc bus engine, fitted with late model stock fan and standard diameter crankshaft pulley.

(http://www.johnmaherracing.co.uk/images/flowbench/belt_on_off.gif)

The blue lines depict horsepower.
Green lines are torque.

As rpm increases, power taken to drive the fan increases exponentially.
At 3000rpm, the fan takes less than 4bhp.
At 5700rpm (cursor location) the power difference is a little over 13bhp.
At 6000rpm it's up to 18bhp.

It's possible there may have been some belt slip at higher rpm levels, in which case the power differential would be greater than shown.
I ran several repeat no-change tests to hopefully eliminate that as a possibility. Of course the belt could have been slipping to some degree but unless it was by the the same amount at the same rpm each time, the repeat tests told me otherwise.

The engine was fitted with a 75amp alternator, which consumes around 1.5bhp. It'd be a little less for the 55amp version.

I've run similar tests on subsequent engines and have found the power differential very similar across the rpm range i.e. as you would expect, power taken to drive the fan is consistent, regardless of engine capacity or power output (using same fan and pulley combination).

Note: these tests were carried out on an engine dyno and represent power 'at the flywheel'.

 8)cant wait to try running without the belt  :)