ALFAGTV6.COM

[kevin]

Pipe is 3'' - 75mm , not sure if that makes any difference. Just another interesting obsevation on previous discussion was a standard gtv3.0l carb with 'standard' suspension(powerflex dedion bush and castor arms and 30mm antiroll bar) including ride height(on semi slicks) was quicker by five seconds than my 3.2gta(full specs as mentioned above) on road tyres. Even chainged drivers around to make sure.
Carby GTV has standard brakes as well.

[kevin]

Pipe is 3'' - 75mm , not sure if that makes any difference. Just another interesting obsevation on previous discussion was a standard gtv3.0l carb with 'standard' suspension(powerflex dedion bush and castor arms and 30mm antiroll bar) including ride height(on semi slicks) was quicker by five seconds than my 3.2gta(full specs as mentioned above) on road tyres. Even chainged drivers around to make sure.
Carby GTV has standard brakes as well.

[Mats]

It would be very interesting to see a video fron inside the car when driven hard, to se how it moves and how it responds from steering input and such.

[MD]

Guys, for what it's worth, I have had a 100mm I.D. smooth bore mild steel pipe flow tested and it's good for at least 520 bhp.

[kevin]

MD, thats exactly the results Im searching for. Do you think if I went to 150mm I could see 780hp.
Mats, I am going to put another set of road tyres on the car because it cant believe it can be that far off and vice versa to put a set of semi slicks on it.
There is no understeer with road tyres only oversteer. This 3.2 is very torquey and just a touch of gas pulls it out. Would have been good to have a camera in the car as I had a big off into the long grass and struggled to find the circuit again( zero maintenance at this particular track). I think its actualy great driver training as you are constantly drifting(not as in Tokyo drift) through every corner and whatever happens you dont take your foot of the gas as that totally flicks the car around. Its no wonder the drivers from Scandanavian countries are the best in the world as they are constantly on ice.

[Mats]

We are constantly on ice? Guess we should have the best runners too since we always have to run from the polar bears?

Isn't it a bad idea to have a convertible in Africa because of all the lions, tigers and other wild animals? What about the rhinos, are all African cars reinforced to take a rhino attack?

[Fernando]

Mats you have a wicked sense of humour... Mats up until the early 1960's in South Africa you still ran the risk of being chomped by a lion if you stopped in the country side between towns.I will never forget reading of a poor woman,back in 1959,whose hubby had to stop for her to take a quick call of nature on their way to Pietersburg.Wife goes behind a bush never to reapear.Lion came from behind and killed her!

Sorry for the hijack Kevin.After chatting to you yesterday I recalled a trackday a few years back with the 3 litre when I hooked up with a 1980's Porsche 911.We were level pegged running down the back straight at Zwarties,both of us braked as late as possible but holy moly he left me for dead through the right hander.I mean I had to hug the apex like my life depended on it and let her drift right on to the rumble strip such was the speed I carried into that corner.My Goodyear Eagle F1's were howling at the treatment,but that Porsche was gone.

When I pitted I went to look at his tyres,Bridgestone semi slicks for the win. No way a road tyre is going to match a good semi slick even though I had fun trying.

[kevin]

Mats, toppic for debate here. On page fifteen I was not sure if it would make any difference which direction you put torsion bars in as I had lost the marks on my 28mm Autodelta bars. On further investigation in this area (as I wanted to make a few sets of 28mm and 33mm bars) I discovered why they work properly in only one direction ONLY
After looking up(Wikipedia) Young's modulus, Hookes Law, discolations, work hardening, yield strength and then looking at the process they make torsion bars here in SA it can be explained. Basically in order to stregthen the bars they are work hardened or scragged(term used here). This is done by loading bars through the elastic limit into the plastic limit a few times(calculated). By doing this it introduces discolations which increases the density of the material which inturn increases the yield strenth which means more stresses can be applied.(whew). As in the case of torsion the atoms on the outside of the bar are intoduced first into the plastic limit before the atoms in the centre. A curve can be drawn from the centre to the edge of the bar defining this area. As mentioned its a curve in the direction it has been work hardened in. These torsion bars are only work hardened in one direction.Therefore if you had to load the bar in the other direction it would not have the same strenght.
The only way I can test the direction of my unmaked bars is make a small jig and load them with same weight in both directions and see which direction rotates the least and that will be the direction it was work hardened.
So, if you say you got them in the wrong direction all that will be different is the loading. Unfortunately NOT as a material that has been work hardened follows a different curve back to the Youngs Modulus curve once the load has been released and effect your rebound rate which the Alfa engineers worked out.
At this stage Im not sure If mine are in the correct way but I am not taking them out to check as my cars handling is absolutely brilliant at this stage and far exceeds my driving skills.
Comments, anyone

[Mats]

So how do they get the whole thing to yield at the same time? Splines?

Case hardening would sound like the only way or maybe induction. Delicate process.

[MR2 Zig]

Mats,

work hardening is, like heat treated hardening, a real and actuall thing. Most alloys won't work harden (most carbon steels). It comes from using or bending or drilling or machining the material. Many stainless steel alloys will work harden, ask your local machinist about 304 stainless (a common one) and he will go off the deep end about how you have to have your cutting speed and feed rate just right.

Scott

[kevin]

Hey Maurizio(or any one else) if you out there, I need some calcs that you had somewhere on the forum. Question is if you increase torsion bars from the origional 24mm to 28mm diameter what percent increase in Kgs have you just gone up. Assuming material is identical and bars are both solid. Reason why I ask is i have just put these bars on Konrads race GTV and need to adress the back. Last time I put standard rear springs on test bed they were on 17.5kg's
Cheers
Kevin

[Barry]

Hey Maurizio(or any one else) if you out there, I need some calcs that you had somewhere on the forum. Question is if you increase torsion bars from the original 24mm to 28mm diameter what percent increase in Kgs have you just gone up. Assuming material is identical and bars are both solid. Reason why I ask is i have just put these bars on Konrads race GTV and need to address the back. Last time I put standard rear springs on test bed they were on 17.5kg's
Cheers
Kevin

Nice post..new computer ? hehe...

[Maurizio]

Hey Maurizio(or any one else) if you out there, I need some calcs that you had somewhere on the forum. Question is if you increase torsion bars from the origional 24mm to 28mm diameter what percent increase in Kgs have you just gone up. Assuming material is identical and bars are both solid. Reason why I ask is i have just put these bars on Konrads race GTV and need to adress the back. Last time I put standard rear springs on test bed they were on 17.5kg's
Cheers
Kevin

Simple for torsion the only parameter changed is the diameter and that is D^4

So (28^4/24^4)=1.85 which is an increase of 85%

[kevin]

Thanks Maurizio. Thats a major increase. Next stupid question,what is the 24mm torsion bar equal to in kg per 10mm linear loaded.
Baz, great to have my laptop back with ALL its new programs you kindly loaded.

[Maurizio]

Thanks Maurizio. Thats a major increase. Next stupid question,what is the 24mm torsion bar equal to in kg per 10mm linear loaded.

hmm,

that is a more difficult calculation.
If you want to go this deep you have to start talking abour wheel rates and the torsion bar then gives non real lineair rate, as it has the a arm as attachment that runs around the bar center.

I ones did an qiuck write down for a 75 torsion bar and as a shortcut assumed it be a linear rate.
When I put in 24mm diameter it gives a wheel rate of 19.6N/mm ( 34.8 N/mm at the shock absorber mounting point)
A gtv has longer bar as a 75, don't know the exact number, but that will only change the stiffness in a linear rate .