alfetta gtv rwhp

[carlo rossi]

This rear wheel power figure is like trying to find out are you above or below average in other bits
This figure is grossly enhanced and unless its got 200 + hp you have a broken motor
Or thats what some have you believe
Ill be brave and start and I hope others follow
WHY? So that we know  if we have a good or sick motor
and if we change cam,s what is the difference and general interest
Also the figure between a mainline dyno and a Dynamics is around 15hp
so my alfetta 83- 84 gtv is 88hp on mainline and 104 on dynamics pre pollution cams and jetting .
stock it was 74 then 78hp ML and 94hp on dynamics ,cams standard but was re jetted
SO jets added around 4hp and the cams added 10hp (10548s) so in all almost 20% increase oh and the torque went thru the roof so if we use mainline 88 and then there is a 33-34% loss with a transaxle ( rubber donuts and such)
so multiply by 1.75 gives you flywheel ( off mainline figure) and we get 154hp flywheel
Hope others can input, it will be great data base !

[festy]

The 2L engine with 10548 cams only made 130hp from the factory, so if after 30 years yours is still making anywhere near that then you're not doing too badly 

[carlo rossi]

then my calcs are all wrong sorry guys but this is waht it is based on
I thought the book said 89kw (122hp) until 84 then 96kw (135hp) all pollution  the later was pollution carbs and bigger cams evidently alot like 10548's the pre pollution 1.8 had 99kw(140hp) with 10548's
so I took an average of122 and the 135 and got 128hp and my stock mainline figure of 74hp leaves 54hp loss
which the old guys will tell you on a transaxle its around a 50hp loss
if you then take 74 multiple by the 1.75 factor i found in earlier post on alfbb you get 129.5hp
it sort of works
now take my current 88 and X 1.75 =154  which means a 15hp gain in rear is around 25 at the flywheel
i might add the carbs are now also pre pollution and up choked and jetted so it means im 10kw more than a 1.8
which sounds reasonable being 10% larger
also the 2000 with 130hp was a spica injected californian pollution model and not 10548 cams
in Italy the cars  was said to be closer to 140 with 1.8 carbs (they  never put the right carbs on)
but thats why I want the results to table and work it all out
to see which of the sources are right
this could be all wrong

[carlo rossi]

thats why Im trying to get rwhp its the only real figure that can be relied on
looking at your charts we can deduce the following
the chart says 130 not 135 on high side and if the 122 stands on the low side
if we do the calc on the low side 122 fly = 74 rear =48hp loss again in the area to be expected
the factor becomes 1.65 not 1.75 for mainline dyno and 1.45 for dynamics dyno
which makes a figure of 145hp flywheel still good
one of the real hot race 2000s posted 124hp rear which would mean 205 hp at the fly
yep it works thats about right so at worst I have 145 (103.5kw) at flywheel not bad
and the 1.7 twin cam 16valve had 85.6hp which X 1.65 and you get 141hp or 101kw
exactly what they had.

they played alot with cam position as well
pre polls had lc's at 102deg, ours had 114deg lc's , the italians had 99.5deg lc's even with the same cam thats a diff of of 15 degrees funny the twin sparks changed by around that amount as well

[GG105]

A while ago I dynoed my Giulia, 2 litre with stock comp, balanced, mild porting and extractors. We got just under 100 rwhp, bearing in mind all dynos are different. I've always thought the factory claims are optimistic and this sort of confirmed it.

[carlo rossi]

yeh sorry sportiva
no just rwhp then you can do your own conversion
standard is good and what type of dyno
mainline ,dynamics or dynajet they all vary
thanks Gg 105
ps use the conversions for flywheel 1.65 or 1.45 depending on the dyno

[Duk]

A while ago I dynoed my Giulia, 2 litre with stock comp, balanced, mild porting and extractors. We got just under 100 rwhp, bearing in mind all dynos are different. I've always thought the factory claims are optimistic and this sort of confirmed it.

If you reckon that's bad, how about the claim that a 131 Supabrava had 120hp...............
Compared to my 1980 Giulietta, with a standard 2 litre, quoted at 120hp,  put in it, it would smash my 131 in a straight line race.

Power claims from manufacturers back in the day were interesting.................. 

[carlo rossi]

thanks Duk
have you had it on a dyno'?
and if so how much and what type?
the fiat engine that virtually became the alfa twin spark
was a newer design with pent roof combustion proven to be better over Hemi
so yes they are similar in power even with 1 less carb
but the alfa motor is visually a nicer motor and I feels better in torque

[Duk]

have you had it on a dyno'?

Haha, sorry, no dyno graphs available for any of my cars. This was all back in poor apprentice days. So about 15 years ago now.

[carlo rossi]

So interesting which is your favourite
the supabrava or giulietta

[Duk]

So interesting which is your favourite
the supabrava or giulietta

I parted ways with both of those cars over 10 years ago.
The Alfa I regretted parting with almost imediately and the FIAT I regretted buying almost imediately...............
My first car was a 132 and that was HEAPS more fun than the Supabrava. And the Giulietta was a great next step on from the 132.
The Supabrava was, in my opinion, 2 or more steps back. It's only redeaming feature was its gearbox, which was a million times better than the Giulietta's.
In a pure horsepower war, there's no doubt that the FIAT engine with a 16 valve head will out grunt the Alfa engine and is physically much more durable, but both cars had standard engines and the FIAT was asthmatic thru its single 2 barrel carb and the Alfa had its twin Delorto's.
The FIAT 2 litre engine also has 2mm more crank stroke than the Alfa 2 litre engine, so great for more low rpm torque, and the 131 had taller gearing (3.7:1 I think), but it hated to rev. They are a great engine, but not in standard form.

Now a days, either would have been fuel injected, with a programmable computer (doing ignition timing too) and turbo'd.

But you just can't hide that accountant's front suspension design in the 131..............  Cheap horrible rubbish!

[ALF750]

My standard 1991 75TS had ~121RWHP, can't remember the dyno make tho.

[julianB]

The dyno operators I've dealt with and all my mates in the performance world, who are regularly tuning cars, say that rwhp figures are only comparable when done on the same dyno, operated by the same guy, preferably on the Same day at similar temperature!

My car has made 178, 188 and 192 rwhp on three separate occasions- the only changes to the tune  done after the first run were idle changes and I said "why don't we just do a quick run to see what it makes"... Take the figures with a grain of salt!

[carlo rossi]

absolutely that is why it is important to know what brand dyno  it is
Mainline is probably the most comparable due to the weather station they have in built
Not saying the others are wrong its just you can use a mainline in Melbourne and one in Darwin and as
long as they are serious dyno tuners you will get results that you can compare
recently in my e arlier post you will see 2 days apart same tune 2 different dyno brands and 16hp difference
yet when i went back to another mainline dyno same result within 0.5hp
So I love the dynamics figure but for tuning variations Mainline is my Baseline

[Duk]

Are you using different dyno readouts for comparisons between your and someone else's car or a tuning session?

At the end of the day, a dyno is a measuring tool and not much more. If you are doing tuning on multiple days and/or multiple dynos, I don't see a problem so long as you start each new session with a base run.
If dyno 'A' differs from dyno 'B' by 20% (or any other number), who cares? It's not as if your car has gained or lost power.
But if after making changes you car gains or looses (say) 10hp over the initial base run, you've gained or lost 10hp.