Alfa Romeo Owners Club of Australia Forum

General Category => General Discussion => Topic started by: Alfatango on January 22, 2022, 07:27:11 PM

Title: 105 v Alfetta v 75 Track Times. Whats better?
Post by: Alfatango on January 22, 2022, 07:27:11 PM
Hey all, I was watching this video at PI of a 105, Alfetta and 75 all following each other https://m.youtube.com/watch?v=c_i8eNmFTFw . No one is really pulling away from each other.

So this leads me to a question, whats the better base to build a car to get the fastest time at a track like PI? But more specifically from a financial perspectice, what makes a faster race car an alfetta or 75? Because there are LOT of alfetta race cars that come up for sale compared to 75s. Also if money was no object would a 105 with a similar build be faster than an alfetta or 75?

Also would anyone have the factory weights of just the engine for all the engine options for all 3 cars?
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: MD on January 24, 2022, 08:15:05 AM
Alfatango,

Great to see enthusiasm out there. Never let that die. However, your choice of an Alfa Romeo vehicle (any contempory street model) for a Time Attack application is frankly pissing in the wind.  For many and different reasons, none are specifically suitable for that purpose. Some are tail happy, some have weak and slow gearboxes, some are too front heavy and out of balance and  so on.That is not to say these same cars are not fit for the purpose they were made for in the first place and often small refinements make them a sheer joy for the original intended purpose which is not Time Attack.

Your judgement about the pros and cons of the vehicle you have nominated and running at PI in the video link is a complete  waste of time. We have no idea of too many variable factors why one car does not pass another.

Driver ability
Driver confidence
Relative engine power
Relative gear ratios in use
Comparison of tyre compounds
Amount of weight reduction
Chassis development  to name some

None of the above is known from a simple viewing of that video and so no judgment can be made whatsoever.

If you decide to dismiss my views and carry on, about the ONLY tip I will give you is to start by concentrating on the best possible power to weight ratio.

If you insist on dreaming on and you imagine that money is no object, buy a Sud Sprint. Tear all the guts out of it. Do a 4 WD conversion. Install DC motors front and rear with a battery pack in the centre . Invest in some welded on underwear 'cause the this Alfa will tear the fork outta yer nightie.  ;D
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: MD on January 24, 2022, 08:27:37 AM
A bit more on the problems of choosing cars. A power to weight example.

Take these two 4 door 5 seater street version sedans as comparisons:-

Alfa 75 series 1.6 litre version in Italy weighs about 1250kg
Datsun 1600, 1.6 (so called P510) weighs about 850kg

So the same 4 door 5 passenger cars have a difference with full trim of 400 kg. That is a HUGE amount. Is it any wonder the P510 was such a global success in rally work for two wheel rear drive cars !!
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: MD on January 24, 2022, 09:52:23 AM
If you examine the technical specs of the 75 and the Alfetta in terms of weight, you will find not much appreciable difference.
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: MD on January 24, 2022, 11:09:09 AM
Perhaps I should let other knowledgeable members provide some responses for you from a likely different perspective . I am sure others will agree that to get into Time Attack times, the biggest prerequisite will be deep pockets whatever car you finally chose to work with.
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: Sheldon McIntosh on January 24, 2022, 07:21:17 PM
As with MDs response, too many variables in your original post.  The Alfetta Group S is a 2 litre twincam, the 105 is I think a Group S, so probably a 1750 (but I don't know, could be a 2 litre), the 75 is a TS, probably standard engine, but I don't know, so no way of knowing which has what power etc.  Let alone getting into driver ability, tyres etc.

But just some thoughts, some based on experience, some on anecdotes.  105s will be a bit lighter than the other 2, but handling a bit more tricky on the limit.  Alfetta and 75/Giulietta/90 are all far more neutral handling due to the transaxle, providing far more balanced weight distribution.   Alfetta will be lighter than a 75, but not by much, shorter wheelbase so should handle better than a 75, but the 75 would be a little more stable at a fast track like PI. 

Then, which engine would you like?  Of course, money being no object, any engine can be fitted into any car (within limits).  But realistically, the most powerful you'll get into a 105 is a TS with some serious modifications.  With an Alfetta or a 75, well, if you're going for outright speed, you're looking at putting a V6 in, or just getting a GTV6 or a 75 V6 in the first place. 

Personally, with the prices of 105s and Alfettas these days, no way I'd be turning one of them into a track car.  And 75s are starting to go that way also. 

I'm surprised you say you've seen more Alfetta race cars than 75s, that wouldn't be my experience.  And watch all the Alfettas and GTV6s get turned back into road cars in the next few years.....

I'd be getting the cheapest 75 or 90 with a V6 I could ASAP if you were serious about it.  And then plan on spending a LOT of money making it fast (does anyone even make big torsion bars these days?).  Or, just buy the quickest race car already built you can find, they are out there.

Or you can buy my slightly rusty 90 sitting in my yard if you want, comes with a free bolt-in rollcage!!
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: Sheldon McIntosh on January 24, 2022, 07:30:25 PM
And just to mix things up, here's another vid from the same event as your original post, me in my 90 with a 3.0 12v, against a 1.5 Alfasud Sprint 1.5 with a faster driver.  Which car is faster....?


https://www.youtube.com/watch?v=clgfR4qyMjQ
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: aggie57 on January 30, 2022, 01:10:56 PM
Sheldon is right, a 116 series car is by design better suited to tracks like the Island.  In the early days there, back to back Alfetta's were faster than similar spec 105's.  You can feel it on the track at corners like turn 1 and Lukey, a 116 is just more stable.  I remember following Frank Porter around the very first day we had access to it after it reopened, him in an auto 75 demo and being amazed at how settled it was in fast corners. 

On tighter tracks like Winton the difference is less pronounced, if anything the better immediate turn in of a 105 helps.  But even then with a few mods you could get a pretty standard 116 coupe around the short track faster than a similar 105. 

Why are there more Alfetta GTV's than 75's?  I've been out of Oz for a few years but in the early days you could buy a GT/GTV for not much money and really nobody wanted to punt a sedan around.  People like Michael Ponchard did wonderous things with 90's and suchlike but that was the exception. 
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: Alfetta77 on February 03, 2022, 08:35:22 AM
My two bobs worth - the coupe design of the Alfetta has been more popular, and they haven't been as rare as 75's (although getting that way), so more have been either raced or restored. Don't get me wrong, a nicely done 75 can look awesome, I just don't think as many people have been inclined to put time / effort in. There are still Alfetta project cars out there for circa $5k so I say go ahead and build a race car if you want to, I hear you re historic livery too. Something I would like to do myself one day (if I ever finish my road car  :)
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: Joe Falcone on February 05, 2022, 04:44:30 PM
Hi guys
From my experience id have to say that a well sorted alfetta gtv with 20l ts engine and gearbox
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: Joe Falcone on February 05, 2022, 04:45:33 PM
is the way to go
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: vin sharp on February 05, 2022, 08:32:13 PM
 ::)Good GpS historic Alfettas and 105s will do 1.54secs and under at Phillip Island, with 60+ year olds driving... That's with a Nord engine on carbs, 185/60 treaded race tyres and standard size solid brakes and calipers, and all steel body. An equally set up 75 would match that or within tenths.
How many very modded, stripped & lightened Alfas ever get near that potential?   ::)
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: MD on February 05, 2022, 09:37:49 PM
In your line up, we don't have a comparison of apples with apples.

For a true comparison, the vehicles would have to be modified so they have identical power to weight. Use the same control tyres and brake materials. Getting equivalent suspension set ups would be problematic.The same driver would need to do the performance tests. All a bit of a mission so your best research would be to follow the Alfa racing globally and see which cars consistently perform the best or have done so in the relative past.

Once you make a choice then get cranking single minded until your world beating Sud is accomplished.  8)
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: aggie57 on February 05, 2022, 10:31:47 PM
Quote from: vin sharp on February 05, 2022, 08:32:13 PM
::)Good GpS historic Alfettas and 105s will do 1.54secs and under at Phillip Island, with 60+ year olds driving... That's with a Nord engine on carbs, 185/60 treaded race tyres and standard size solid brakes and calipers, and all steel body. An equally set up 75 would match that or within tenths.
How many very modded, stripped & lightened Alfas ever get near that potential?   ::)

Remember when sub-2 minutes was considered quick?  Is it tyres that have improved this much or?
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: vin sharp on February 05, 2022, 10:38:59 PM
Until a driver can consistently be winning the class or right at the front of the class for his current car, getting the maximum out of both the car and driver, it's pointless to chase theoretical times in modified cars.
There's nothing more comical than seeing a flared, lightened, winged and spoilered, all-tech DRM/Supercar lookalike being flogged by a relatively stock looking car with 6 inch rims, skinny tyres and a 1950's engine design with carbies!
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: vin sharp on February 05, 2022, 10:49:38 PM
Quote from: aggie57 on February 05, 2022, 10:31:47 PM
Quote from: vin sharp on February 05, 2022, 08:32:13 PM
::)Good GpS historic Alfettas and 105s will do 1.54secs and under at Phillip Island, with 60+ year olds driving... That's with a Nord engine on carbs, 185/60 treaded race tyres and standard size solid brakes and calipers, and all steel body. An equally set up 75 would match that or within tenths.
How many very modded, stripped & lightened Alfas ever get near that potential?   ::)

Remember when sub-2 minutes was considered quick?  Is it tyres that have improved this much or?

It's a bit of everything, nothing stays static. Drivers in particular learning how to make the best of what they are limited to within the  historic class.   Shows what can be achieved with what is a relatively mild allowance for changes from the production car.
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: aggie57 on February 06, 2022, 04:04:25 PM
That's still a lot faster, it wasn't that long ago that the very fastest club cars were only around 1:50.  I'd have to go back and check times from 10-15 years ago to be more specific. 
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: Paul Gulliver on February 06, 2022, 11:20:00 PM
Further to Vin & Aggies point about time never stands still, well apparently that's true in 2 litre  Alfetta land as well. A quick but by no means exhaustive search of Natsoft results shows that around 2000 . Joe Ardi was the man to beat in  Alfetta's . A 1.58 at Philip Island in Marque Sports. A few years later in early Group Sc in around 2007 Phil Baskett was again doing 1.58. (different class / different rules) . 2021 Hugh Harrison in group SC had lowered the bar to 1;54 Secs. (Sorry Vin i was unable to access their birth certificates)

Joe Falcone mentioned earlier that a twin spark Alfetta GTV would be the way to go. I tend to agree as i have a road registered one in the garage. I haven't been doing any club sprinting for a couple of years now , but when i was Joe had a reasonably well sorted road registered Alfa 75 TS ( apart from undersized torsion bars ) . Over 3 years there was never more than a second between us at PI , Sandown or Winton.
Your also mentioned you tube clips. If you want some real excitment look up Steve Aarons in an Alfetta Twin Spark at Philip Island . The 100mph power slide through turn 1 at PI wasn't bad . Or spinning 360 degrees and pulling up straight going down the main straight in torrential rain after an innocent enough gear change ( i was behind him for that one and had to close my eyes , i couldn't watch) . That boy will never die wondering.         
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: Joe Falcone on February 07, 2022, 09:40:45 AM
Yes Paul smile factor and Marcus's lap times would favour our point of view
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: Colin Edwards on February 07, 2022, 10:43:21 AM
Yes.  Difficult to compare apples with oranges. 
Most things being equal, the Alfetta is around 100kg lighter than the 75, however the 75 would have 10% more power.  The 75 is about 30mm taller than the Alfetta, while both have a similar track.  The 75 would likely have a higher CoG and transfer more load, however the 75 being a later design "should" have a torsionally stiffer chassis.  Then again the 75 is more aerodynamic!
  Decisions decisions.

Both are very collectible - the Alfetta more so, however the 75 is catching up!   

A 1.4 Multiair equipped Mito would be way faster, and safer - and for the moment, less collectable!
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: Paul Gulliver on February 07, 2022, 01:53:51 PM
Joe Falcone "Yes Paul smile factor and Marcus's lap times would favour our point of view"

Right again Joe and apologies to Marcus Gordon 1min .52sec . in an Alfetta GTV TS sports sedan . ( does make Hughs time look remarkable) . Pushing the envelope a little further Peter Beninca's low flying aircraft Alfetta based sports sedan 1min 39 sec at the Island.  Nearly forgot the ultimate expression of Alfetta . The Tony Ricciardello Chevy / Alfetta. 1min 29 secs at the Island

They just ought to start making Alfetta's again in kit form. Just tick Chevy for engine option
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: Beatle on February 08, 2022, 09:40:46 AM
Quote from: Alfatango on February 05, 2022, 10:22:20 PM
Think of this as pub talk rather than science ;D.

OK, given this is pub talk, and we've now introduced Chev V8 engines... ::)   how's about actually building a car.  A spaceframe chassis with mid-engine 3.2V6?   Or Alfetta transaxle-based RWD V6.  Might give one the opportunity to 'correct' any geometry issues with the road car chassis (roll centres etc) and should be significantly lighter than any 116/160 RWD. 
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: GTVeloce on May 04, 2022, 12:56:01 PM
There is a company in Switzerland (OKTech) who is producing some amazing stuff with mostly GTV6's and 75's. Certainly his engine work (almost all N/A V6 related) has to be up there. I couldn't find the video I wanted but this shows a 75 race-car he has produced that, in the right hands, should be quick.
https://www.youtube.com/watch?v=pR2XgWQjNL0
If you are on Instagram, check out his engine building work!
Title: Re: 105 v Alfetta v 75 Track Times. Whats better?
Post by: alfettaman on October 07, 2023, 05:12:03 PM
Just for the record

December 5 1999 Aroca club sprint i achieved a lap time of 1:54:84 in this 2 litre alfetta GTV

Joe Ardi