V6 Strong modification

[Gabor K.]

Interesting, as I see, however why not go race style alltogether and close the bottom of the frame and get dry sump with the bottom bearing carriers. You will than have a lower engine center, the increased rigidity, but must have an external oil pump for each oil cavity.

[slyalfa]

That is what I was thinking. but also add a triangle too so the side of the cap is locked in.
And mabee weld the caps to it...
The bolts of the caps would need to be longer or the caps shaved down.
even if it is just a bolt on it might make sence to mill the caps down where it mates to the bedplate as the bed plate will add back the thickness. Then the fit will be dead on. Right now the caps are cast on that end and the fit would be vey bad. and some caps 164s have a flate spot to mount the oil pick up on one cap.

if the caps are milled it might be good to leave a rased part in the center to help lock the cap.
a round peg that fits in a drilled hole in the bedplate.

[FMG_V6_btb]

If you decide to use an integral bottom frame with the bearing caps included, you will need to realign (mechanize) the entire bearings line, and that could be critical if you want to maintain the original bearings and crank.

Closing the bottom like race engines will add stiffness, but will make the part more difficult to manufacture, and the necessity of three external scavenge pumps...

If you look to the design, the side of the bearing caps are locked, so the triangle shape is not needed, also note that it is necessary to have some "windows" between pair of cylinders to allow the internal air in the crankcase to circulate (pumping effect of the lower part of the pistons), so the triangular space is needed.

I don’t recommend welding or cutting the original bearing caps, which could deform or impair those critical parts.

Longer bolts are needed, and round pegs could be inserted in the main bearing bolt holes to add some more stiffness.

Paco.

[slyalfa]

hmm welding I could see, but I would not think milling would deform them. the part to mill is quit far from the crank and I would not think taking some off would affect it. and if they were milled flate the bedplate could lock on the them, and the milling of the bedplate would be easy as a standard pocket mill would be used insted of a very slow $$$ many many pass to make up the curved part.

[daz]

Paco
this thread is extremley interesting and I hope you keep us all informed as to your progress and finished product.
Im no engineer just a do it yourself enthusiast and although this is beyond me its still a worthwhile thread, its a fresh approach and hasnt been discussed a thousand times before
Keep it going

[FMG_V6_btb]

Sorry guys, I'm really very busy but don't forget the thread, I will continue with it ASAP.

Thanks

[SovraPressione]

Paco this thread is extremely interesting please continue posting, to completion we hope.

We Alfa enthusiasts need these as there are not much "open" concept on this matter in comparison to the Hondas, Nissans , Mitsus engines etc out there where they seem to have everything developed by zillions of their enthusiasts for the benefit of the end users.

Whether it will be on an Alfa chassis that is a different matter,the Alfa V6 engine is the soul of the marque in the first place.

[Kevin Johnson]

Quote:

Originally Posted by FMG_V6_btb Maybe some of you would be interested in my project... I have planned to modify deeply a 3.0 V6 24 Valve engine, to obtain a reliable 450-475 HP engine. The engine will be twin turbo, and the cylinder capacity maximized to be around 3.8 litres. Since I have seen in the net many V6 engines with crank-rod failures (as mine), to build a reliable engine, means to solved this problem, and the better way is to design a new crankshaft with increased stroke and rod journal diameter and width (lower bearing surface pressure):

[FMG_V6_btb]

Hi Kevin, I have been analyzing the possibility of design and manufacture a new crank with increased stroke, there is no problem in doing that, the problem arises when try to assemble it to the rest of the engine.

Design a new crank only worth if the stroke is substantially increased, as this engine can be easily fitted with a 78 mm stroke GTA crank, a new design must have as least 82 mm stroke, and this produces the following 2 problems:

1 Due to the relatively short rod, the resulted maximum rod angles are the following:
72.6 mm stroke = 16.7 deg.
78 mm stroke = 17.3 deg.
82 mm stroke = 18.2 deg.
16 deg. is near of the “normal” limit (lateral forces between piston and liner), so this engine with a 78 mm stroke crank is a little saturated, and much more with an 82 mm stroke crank.

2 In order to (almost) maintain the crank rigidity, the connecting rod journal diameter must be increased, and this is a problem because this engine has big diameter journals and increasing it would produce a very wide rod big end which together with the increased stroke would made the rod touch inside the crankcase, specially in the area near the liner end of the opposite cylinder.

So, I think is justified NOT design a new crank, and use a 78 mm GTA one instead.

About crank failure, I think the reinforcement of the main caps and engine structure with a girdle will allow the crank to work in better conditions, and if the oil system is revised and improved (flow capacity and temperature control), I hope the crank will last a little more (taking control of the maximum in cylinder pressure, knock, etc.).

Thanks

Paco

[Kevin Johnson]

Quote:

Originally Posted by FMG_V6_btb ... About crank failure, I think the reinforcement of the main caps and engine structure with a girdle will allow the crank to work in better conditions, and if the oil system is revised and improved (flow capacity and temperature control), I hope the crank will last a little more (taking control of the maximum in cylinder pressure, knock, etc.). Thanks Paco

[alfaspence]

Not sure if anyone had mentioned this before, but whats wrong with polishing and shot peening the rods and crank? This method of strengthening is age old and produces good results....
Detonation should be addressed and cured, not masked up with stronger components...

Why 3.8? i know theres no substitute for cubes, but really, if you design the intakes and exhausts correctly, cam profile selection also, theres no reason why you shouldn't be able to see near 450 bhp from a twin turbo 3 ltr 24v running approx 8-12 pounds of boost (pump gas)

If i had the funding, i would be more than willing to put this theory into practice

Before anyone attacks, i have been in (and out) of engines for a good 14 years now, and had very good results arising from work that i have done...
(but i work from old fashion methods, not new computer generated ones, allthough iam not saying that new technology is all bad tho)

[Kevin Johnson]

Quote:

Originally Posted by alfaspence Not sure if anyone had mentioned this before, but whats wrong with polishing and shot peening the rods and crank? This method of strengthening is age old and produces good results....

[Gabor K.]

Paco: You could just buy a 450Hp crank instead of trying to work out something yourself, unless you can make something for free? Have you checked?

[alfaspence]

Quote:

Originally Posted by Gabor K. Something like this for the road? This one is without turbo and around 450Hp.

[alfaspence]

Quote:

Originally Posted by Kevin Johnson Those are good techniques. Two questions pop into my head -- neither of which may apply to the V6 under discussion: 1) If the crank has already been hardened in some way is shot peening safe or simply redundant?; 2) Does or did the engine ever use powdered metal rods and is shot peening safe or recommended? Perhaps in 1) the grinding/polishing removes the hardened layer. Anyway, easier to ask about this now than to contemplate a collection of unusual steel paperweights.