Boring out an '86 2.5 gtv6

[mjr]

NO. for a start, none of the oil and water galleries line up with the 12v blocks. the combustion chambers are a also a different design, you would end up with odd compression

[as-of-now]

Quote:

Originally Posted by mjr you can't bore out any of the alfa V6's, they are alloy wet liner engines. you can only machine the blocks, to take a larger liner. for the 2.5, I believe 2.8 is the largest you can go, without weakening the block. whilst for the 3.0. 3.5 and for the 3.2. 3.7. you wont achieve any of the above options for 5k imo. a simple rebuild will cost close to that on its own. cheapest option is a good milano 3.0 12v verde, with cams, headers, ported runners etc.

[Gabor K.]

I think what you missed is that a big bore kit could be more expensive than a complete bigger engine. The less expensive way is to put in a bigger engine with some minor changes as cams and headers, that will give very good results. Boring up a block and installing new liners and pistons is very expensive and then you never can use original parts any more, totally dependent that the supplyer company keeps alive to supply the right spare parts.
Big bore kits have been along since early nineties, supplied by Dieter Gleich, Germany and Sam van Lingen(SAVALI, Holland). Nowadays there is a company in UK that makes big bore kits for a price. But chances are you would be just as happy with a lightly tuned Alfa 75/164 3L 12V engine(200hp) or a 3L 24V 164 (210Hp), or even a 3,2 24V GTA engine with 250Hp.

Here the link to AHM Motorsports,

Parts

[mjr]

yup agree with that too. just remember tho, if you go for a gta 3.2 or 164qv say, you will need the ecu with it. Ljet 2.5 ecu wont be up to the job for the 24valve. if you can find a 164 24v s or qv that doesnt need a rebuild, you could do it for 5k

[as-of-now]

Quote:

Originally Posted by Gabor K. I think what you missed is that a big bore kit could be more expensive than a complete bigger engine. The less expensive way is to put in a bigger engine with some minor changes as cams and headers, that will give very good results. Boring up a block and installing new liners and pistons is very expensive and then you never can use original parts any more, totally dependent that the supplyer company keeps alive to supply the right spare parts. Big bore kits have been along since early nineties, supplied by Dieter Gleich, Germany and Sam van Lingen(SAVALI, Holland). Nowadays there is a company in UK that makes big bore kits for a price. But chances are you would be just as happy with a lightly tuned Alfa 75/164 3L 12V engine(200hp) or a 3L 24V 164 (210Hp), or even a 3,2 24V GTA engine with 250Hp. AHM Motorsports, UK Alfa Romeo Bulletin Board & Forums

[as-of-now]

Quote:

Originally Posted by mjr yup agree with that too. just remember tho, if you go for a gta 3.2 or 164qv say, you will need the ecu with it. Ljet 2.5 ecu wont be up to the job for the 24valve. if you can find a 164 24v s or qv that doesnt need a rebuild, you could do it for 5k

[mjr]

10k to mount a 16424v? no way!. a good motor not needing a rebuild, would cost no where near that to install. IMo more like 6k by the time you have baught the scrap bits needed to covert it

no 3.012v normally aspirated, even modified, will come anywhere near a SC 2.5

Im getting the impression that your are wanting to keep your 2.5 to reduce cost. if that is the case the SC is the only smart option. And by the way. a SC 2.5 running 10psi boost and water meth, will put out more power and torque than the 16424v LS engine anyway.

[Gabor K.]

As of now: Yes there are some afficionados that have a 2.5 sound-fetish, with all respect. However the slightly tuned 3L 12V is much better to drive power and torquewise and I even like the sound of the 3L better as it revs just as well and has more full voice.

For your info there is a 164 3L 12V conversion to GTV6 description on alfagtv6.com which you could read to get an idea about the size of the work.

[mjr]

you miss th epoint as- of - now. I only favour the 2.5 over the 3.0 if supercharged, because you are looking for the cheapest option. i.e SC what you have, and yes that will totally outclass a naturally aspired 3.0 verde 12v, for both HP and torque by a long way. if you are not bothered about keeping the 2.5, then the 3.0 is the way to go for normally aspired and SC too. But for 5k, you are not going to get a 3.012v modify it, fit and get anywhere near the power and torque from supercharging what you already have. Its a question of your preferance really

[as-of-now]

Let me know if I got it...

In terms of power an sc 2.5 is the way to go.

The only thing that may come close to that, is the 3.0 24v, and even that isn't a sure thing. - and it's a bit more expensive, around 6k.

Are we good up to here?


I like the idea of a naturally aspirated engine, but it just might not be worth it to spend the extra bucks if a simple sc will do the trick in terms of giving me power.

If the 3.0 24v is no match in performance, and more expensive...

then the only remaining question is whether to sc or turbo, and because the engine isn't a tourquey one to begin with, sc is probably the way to go.

If the 3.0 24v is a match in performance, and not so much more money...

I go for an LS because I won't have to change the ecu



thanks for bearing with the ignorance of someone who's new to this whole thing...

[Gabor K.]

Just for the record, the 3L 24V with 210 hp is no match for a 280 Hp 2.5 supercharged or twin turboed. However the 3.2 GTA with original 250 Hp is much closer, and this one can be tuned to deliver the same amont of power as the force fed 2.5. Pricewise I think the same amonunt of money would be spent in both projects. However the 3.2 GTA would probably be the simplest solution technically, specially in comparison to a twin turbo.

[as-of-now]

Quote:

Originally Posted by Gabor K. Just for the record, the 3L 24V with 210 hp is no match for a 280 Hp 2.5 supercharged or twin turboed. However the 3.2 GTA with original 250 Hp is much closer, and this one can be tuned to deliver the same amont of power as the force fed 2.5. Pricewise I think the same amonunt of money would be spent in both projects. However the 3.2 GTA would probably be the simplest solution technically, specially in comparison to a twin turbo.

[as-of-now]

by the way, Greg's website is HI Performance Store, Inc

I wonder if there are guys in northern ca with this kind of a kit - anyone have any ideas?

[ToonRboy]

Marketing is a wonderful thing. 5-6k? That'll get chugged as quickly as a quart of Budweiser after a softball game in summertime!

I'd say take a look here and talk to Greg. Supercharger Kit

From his web page,

Quote:

Using pump gas an otherwise completely stock 2.5 can put out about 220 horsepower. My 2.5 put out about 250 hp with a MP62x at 10 psi and with programmable water injection. That's a stock engine using L-Jet!

[as-of-now]

Quote:

Originally Posted by ToonRboy Marketing is a wonderful thing. 5-6k? That'll get chugged as quickly as a quart of Budweiser after a softball game in summertime! I'd say take a look here and talk to Greg. Supercharger Kit From his web page, Greg should be able to give you specifics on how he got there, but I'm pretty sure the stock injectors would be maxed-out at just under 200hp. From all accounts, the low-Z injectors (151, 152 barbed) are very difficult to find (stock are 105's rated at 188cc [new]). You need this type to keep L-Jet. So, you will have to deal with fuel augmentation (add cost). Probably your best bet. There are some good threads about conversions of say, the 164S engine (and respective engine management system). The guys who have done this (and 24 valve conversions) are experienced and pure enthusiasts. Truthful Alfisti will tell you up front that they spent your budget (and more) and did 90% of the labor themselves. That where the real expense is.