V6 Strong modification

[junglejustice]

400-plus (crank) horses from an NA 3.7 litre 24 valve Alfa V6 is no longer a mystery - its pretty much a foregone conclusion...! 12 valvers won't touch that in NA - not even close - you need the 24 valve setup at that point.

As far as the old "no substitute for cubic inches" argument; yes - this also holds true when you are talking big-bore Alfas (they really need the CCs!) With it however, comes commensurate risk - the heads won't seal and an increase to the combustion-dome, protrudes in to the water-jackets (even MORE so on a 12 valve head!)

At the same time, we're talking 10's of CCs - right? If you can't make the power off of 3.6, 3.65, or 3.7 litres, you're not going to make it off of 3.8 litres either, so why stretch it to say a 101, 102, 102.5, 103mm bore-size?

I know of properly built 3.45s even (still on "amateur" budgets), that smoke 3.8s built on similar budgets (but with less experience behind it...) If the basics are good, the thing will make power. Ports, compression, cams, valve-angles and most of all - mapping!

[alfaspence]

Quote:

Originally Posted by junglejustice big-bore Alfas (they really need the CCs!)

[junglejustice]

Again, I said; "...I know of properly built 3.45s even (still on "amateur" budgets), that smoke 3.8s built on similar budgets (but with less experience behind it...) If the basics are good, the thing will make power..."

So, the 400 plus hp 3.0 that you referenced is NOT and a repeat NOT a motor built on that "amateur" budget that I referenced...

Why stop at 3.0 then in an unfair comparison like that? Why not reference the 11-14K rpm 400-450 hp 2.5 litre 24 valve factor engines from the 155s as a bench-mark for what should be then...? The qualifier here was "..."amateur" budget..."

[alfaspence]

Quote:

Originally Posted by junglejustice If the basics are good, the thing will make power. Ports, compression, cams, valve-angles and most of all - mapping!

[FMG_V6_btb]

Hi all, sorry for the delay in write something in this thread.

The truth is that as I mentioned some posts ago, I’m very busy and have more things to do that I’m able to do (it’s said like that??). On the other hand I’m working in the design of the front subchassis and suspensions of the car on which the engine will be installed, and that takes me time to think about the engine.

I’ve read the discussion about why the “necessity of capacity”, it’s very simple: there is two ways to obtain power for a given engine (generally speaking): the first is increasing the mean effective pressure, and the second increasing the engine speed. In sport engines, where turbos or superchargers are forbidden by regulations, the only way to obtain power is increasing engine speeds and maximum attainable mean effective pressure by means of very well tuned camshafts, valves, intake & exhaust system, EFI, etc…, but a car with an engine like this (Alfa 156 Silhouette sport car for example) will not be suitable for normal use among city traffic.

Turbochargers or superchargers is the solution to attain the desirable level of power in capacity limited engines, without renouncing use the car every day to step through the city.

Turbochargers are typically more efficient, that’s why I want to use a pair of them in my project, the problem with turbos is the lack of power a very low engine speed, that’s the reason to increase the engine capacity to the maximum reasonably possible.

Thanks all… and keep posting!

[Gabor K.]

Why not use a supercharger for bottom and turbocharger for the top if this is within your technical capabilities? Have been done before by Lancia for instance. And as I mentioned before, you can actually buy a 450Hp crackshaft, instead of try and fail yourself.

[FMG_V6_btb]

The target is do it, not buy it, the satisfaction is infinetely bigger, there is a lot of pleasure doing the things you have planned... I feel like an artist...

Paco.

[Gabor K.]

Yes, you must be an artist at the lathe-computer dialing in the figures for the V6 crank with due offset crankpins and boring the oil lines. You definitely must post some photos when its finished!

[FMG_V6_btb]

As I mentioned some post before, I will go for the GTA crank (78 mm stroke) because a 82 mm stroke crank with its rods will be difficult to fit inside the crankcase, so I will not deal with the crank in the lathe.

Paco.

[Gabor K.]

Ah- I did not think about a 82mm crank, but making a crank 78 or 73.6mm that can stand 450 hp and that does not weigh a lot! That is what racing cranks are about They are not heavy like lead and can handle a lot of power.

[FMG_V6_btb]

Due to the lack of information about real measurements of the engine, needed to design the girdle, the top plate-liner, and to check the rods, etc, etc, I have bought an extra 3.0 12V crank, block, and rods, just for measurements and as dummy for the mentioned modifications.

I think have read (can’t remember where) that in the 3.0 12V the block and crank is slightly different to the ones in the 3.0 24V (164 Q), is this true? What are the differences?.

Paco.

[FMG_V6_btb]

Does anyone know if the THS rods may be modified to accommodate a 23mm diameter pin?

Paco.

[FMG_V6_btb]

Regarding pistons and rods for the modification, finally I think it is not necessary to design nothing: I'm studying the possibility to use WISECO forged pistons designed for the Subaru EJ22 engine, these pistons have 98 mm diameter, and shaving 0.5mm it’s heads they have the correct compression height and head volume to obtain a compression ratio of 8,65:1 approximately with the standard 3.0 head, good for turbo application, but (always there is a "but") the pin diameter of these pistons is 23mm (good for the strength), that's the reason why I asked before if somebody knows if the THS rods could be modified to accommodate the 23mm pin, I have asked it to Jim K. because he made the design of these rods.

Another possible issue (has to be verified) is the width of the rod housing in the WISECO-Subaru piston, THS rods have a small end width of 23.7mm, so the WISECO-Subaru piston must to have as least 26mm of room for the rod, but I haven't this information yet... maybe asking to the WISECO guys.

What do you think about this mod?, another way to obtain 98mm pistons? If the Subaru option fails, what's the best choice (price-quality) of forged piston manufacturer for special designs? JE, WISECO, CP, Arias, MAHLE Motorsport, SRP, BME, Ross...

Paco.

[FMG_V6_btb]

It seems there are different opinions regarding the possibility of boring the THS rod small end from 22mm to 23mm:

- Jim K. has told me that it could be honed, and as result the bronze thickness will be a layer of 0.5mm.

- THS people in UK said that to have a larger pin would require a new rod design to be made. they pointed that the minimum quantity for a new design is 5 sets.

I'm not so confident with a 0.5mm bronze layer on the rod small end, IMO is better to increase the rod housing for the bronze from 24mm to 25mm, this way the bronze thickness will continue being 1mm. Can somebody send me or post a sketch of one THS rod? I can model it and make a simulation of before-after modification of the pin diameter.

New rod design can be a good idea if more Alfa enthusiasts (at least 4 more) want to make this same engine modification, and this can be an oportunity to design the rod with all the features to match the selected piston.

Paco

[FMG_V6_btb]

I think this thread is becoming very boring ...