ALFAGTV6.COM

[Peab]

I have a set of pistons and liners for a 2.8L conversion for the 2.5 V6 in the garage, The set has never been used and is actually from the times when Dieter Gleich made 2.8L conversions in the '80ies. I have been tempted by this conversion for some time, but due to the required block machining i put it on hold during my first V6 rebuild. But now when my hot 2.5L is finished and it has been working like a charm during the whole summer, i'm beginning to get the urge for some more engine building again.

So my question is for you guys who have tried the 2.8L before; how does it compare to the Alfa 2.5L / 3.0L ?

From the specs of the Gleich modified engines, i have seen this engine was giving 191bhp which is actually more than a stock 3.0L to my knowledge. And from what i have learned this was still using stock cams(?) and L-Jet. So i guess it should not be too hard to get a 2.8L above the 200bhp mark with my Megasquirt box and a set of other cams.

I have also understood from previous posts that there are two ways to go about it; either start with a 2.5L and machine the block, or use a 3.0 with the 2.5L crank and offset the small end of the rods. For me the 2.5L option seems the esiest, as 2.5s are so easy to get cheap nowadays. The drawback, ofcourse being the smaller valves. Could the 3.0L intake valve be fitted on a 2.5L head ?

But what do you guys say: am i crazy for even considering this coversion, is the 3.0L always the better option? or is the 2.8L something to go for ?

[Barry]

My first thought here would be to say..Go 30l outright to start off with.

Alternativly,30l block and heads,2.5 crank,ofset small end 1.84mm upwards..

A lesser option,but still aceptable,2.5 heads..

Performance wise,the 2.8 falls smack bang in the middle here(all things the same..)
As much as is gained from 2.5 tp 2.8,is again acheived from 2.8 to 30l..

[joey]

hrmm, can't remember what changed when Gleich made the 2.8L w/ 190bhp... I think you're right, it was just the pistons... but i spose from a claimed 160bhp by the factory, a further 30hp is possible(ish) given the capacity increase, but also be mindful that the gleich forged pistions had a lot more compression. Stock being 9 compared to 10.5:1. (i think, either that or 11:1). The 2.8 would have its peak power figures at higher rpm than a stock 3.0 i believe.

Gleich also had a hot version of his conversion. Made around 230-240hp from memory, but that did include bigger valves and cams. Sounds like a serious bit of kit...


onto your last question, i think its awesome that someone would consider this.... does it make sense? well personally i would keep it all gleich and modify a 2.5 as the 3.0 retro option didn't exist back then. Also why mess w/ and add expense to a perfectly good 3.0 to reduce max possible power?

my opinion, it would be wholly justified and worthwhile to pick up a cheap 2.5, possibly one w/ smashed valves or worn pistons or whatever (very tired in other words) and to do the gleich replica properly. JMO.

it would help if you had a machinist for a best mate too

no one could object to that use of a tired old 2.5, but then there are those who would argue that the best use of one of those would be to modify one of those fwd 3.0s to interface w/ a rear transaxle... Whatever floats your boat in the end. A true early 80s gleich replica would be more unique tho... and faithful to the period, even w/ modern management, if that makes sense...

[Peab]

thanks for your thoughts on the subject. I can agree that the 3.0L is the best option when looking at maximum attainable power. But with so many GTV3.0L going about i like to have something a little different. A Gleich replica floats my boat in that respect.

For the serious power of the hot Gleich motor at abt 240hp i think they used abt 320deg duration cams and a lot of lift. Sounds like a setup that would be a bit tricky to use on the road. So i think i set the aimpoint a bit lower, between 200-210 would be realistic i think. What did you get out of your old 2.8L Barry ?

[kterkkila]

I've also been thinking 2.8 for some time, and already got all the parts for the purpose. I'm dreaming of crazy revving Alfa V6. Imagine the screaming sound..

The plan is to use 3.0 block and 2.5 crank.

I sold my 3.0 75 year ago, but have 2.5 project car waiting for better time.. Maybe next year, or year after that

[patzo_3l]

yeh i too also realli like the idea of 3.l block and head with 2.5crank revving to 9000-10000 rpm. my only question is there a cheap way out of organising reliable valve train gear for this sort of rpm. i mean we all know the common answer to this " how much money does one wanna spend" but the fact remains that this sort of stuff doesnt come cheap. has anyone managed to do this previously on a budget?

just my 2 bob.

[kterkkila]

my only question is there a cheap way out of organising reliable valve train gear for this sort of rpm.

Right question. Who's got the answer?

[Sporttunergtv6]

i have a 2.5 turned 2.8... sperry heads, s cams, and 10:1 pistons from the 164 i think. it is a nice motor with more umph than the standard 2.5, but the thing is regardless of how unique the 2.8 motor is, it appears no different from a 2.5 (even the 3.0 valve covers go largely unnoticed). After a while you kind of forget it is even special. With the way 164 values have nose dived, it would probably be best to 164 12v or even 24v your gt6.
good luck building this screamer,
vittorio

[Barry]

Forget the valve train.....How is this thing going to breath for 10000rpm....

[Peab]

The intake plumbing needs to be radically modified to get those rpm figures i guess. But still: do we have any sources for lighter/stronger valves/rockers/pushrods for our alfas? I haven't found anything on the net so far. Only IAP's "performance" valve springs.

[dan668s]

Peab, I would go with the 2.8 option. Like you say, everyone have the 3.0-engine and a stock 3.0 isn't very exciting or high revving.

Of course you could get more power out of a 3.0, but I guess the 2.8 would sound much better, be more unique and more fun.

If you don't do the 2.8 engine I'll buy the parts from you...hehe

[kterkkila]

Forget the valve train.....How is this thing going to breath for 10000rpm....

With a pair of turbos

[Barry]

Forget the valve train.....How is this thing going to breath for 10000rpm....

With a pair of turbos

YEA!!

[patzo_3l]

ok come on ppl. now discounting the fact that the heads would need to be able to flow enough air to be able to make power at these sort of rpm levels and the fact that induction lenghts, exhaust designs and plenty of experimental work would need to go into such a beast, are you telling me that no-one out there has an answer for the valve train??? maybe i should refrase that, i know there is a solution, $$$$$$$$ and plenty of it, but has anyone out there got somewhat of a cheaper soulution that is much kinder to the hip pocket. dont get me wrong things will always cost money and especially a hypothetical beast such as a 2.8l revving to 10 000rpm, but with the market being flodded with high quality copies such as 50 dollar con rods from china im sure its only a matter of time before they start to make other parts such as quality valves, springs etc etc.

[hagen111]

but with the market being flodded with high quality copies such as 50 dollar con rods from china im sure its only a matter of time before they start to make other parts such as quality valves, springs etc etc.

Are you serious about this one? If so, who has experience and where can you source them? How far off are they from Carillos?