2.8L conversion

User avatar
Peab
Silver
Silver
Posts: 45
Joined: Sun Feb 06, 2005 9:07 am
Location: Oslo, Norway
Contact:

2.8L conversion

Post by Peab » Wed Aug 23, 2006 11:35 am

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 ?
User avatar
Barry
Verde
Verde
Posts: 1993
Joined: Sat Nov 27, 2004 1:21 am

Post by Barry » Wed Aug 23, 2006 8:49 pm

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.. :shock:
joey
Gold
Gold
Posts: 192
Joined: Fri Dec 03, 2004 5:36 pm
Location: in a state of limbo

Post by joey » Wed Aug 23, 2006 9:28 pm

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 :wink:

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...
"Fun is an unintended, unforeseen, and usually undignified consequence of life."
User avatar
Peab
Silver
Silver
Posts: 45
Joined: Sun Feb 06, 2005 9:07 am
Location: Oslo, Norway
Contact:

Post by Peab » Wed Aug 23, 2006 10:08 pm

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
Gold
Gold
Posts: 174
Joined: Tue Oct 18, 2005 11:00 am
Location: Finland
Contact:

Post by kterkkila » Thu Aug 24, 2006 3:33 am

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.. :wink:

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 :roll:
Kimmo / alfatune.fi
patzo_3l
Platinum
Platinum
Posts: 223
Joined: Mon Jan 31, 2005 5:59 am
Location: melbourne, australia.

Post by patzo_3l » Thu Aug 24, 2006 4:28 am

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.
patzo_3l

3l gtv6 turbo 85'
2006 147 gta selespeed
1990 75 twinspark
1998 spider
2.0l gtv 85'
33 1.7ie
kterkkila
Gold
Gold
Posts: 174
Joined: Tue Oct 18, 2005 11:00 am
Location: Finland
Contact:

Post by kterkkila » Thu Aug 24, 2006 5:22 am

patzo_3l wrote: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?
Kimmo / alfatune.fi
Sporttunergtv6
Platinum
Platinum
Posts: 360
Joined: Thu Feb 24, 2005 12:55 pm
Location: New York, NY
Contact:

Post by Sporttunergtv6 » Thu Aug 24, 2006 8:14 am

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
User avatar
Barry
Verde
Verde
Posts: 1993
Joined: Sat Nov 27, 2004 1:21 am

Post by Barry » Thu Aug 24, 2006 9:46 am

Forget the valve train.....How is this thing going to breath for 10000rpm.... :?
User avatar
Peab
Silver
Silver
Posts: 45
Joined: Sun Feb 06, 2005 9:07 am
Location: Oslo, Norway
Contact:

Post by Peab » Thu Aug 24, 2006 11:07 am

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.
User avatar
dan668s
Gold
Gold
Posts: 64
Joined: Tue Sep 20, 2005 12:36 pm

Post by dan668s » Thu Aug 24, 2006 9:27 pm

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 :wink:
Alfa Romeo - The thinking man's car!
--------------------------------------------
2004 Alfa Romeo Sportwagon 1.9 JTD
1986 Alfa Romeo GTV6 2.5
kterkkila
Gold
Gold
Posts: 174
Joined: Tue Oct 18, 2005 11:00 am
Location: Finland
Contact:

Post by kterkkila » Sat Aug 26, 2006 11:02 am

Barry wrote:Forget the valve train.....How is this thing going to breath for 10000rpm.... :?
With a pair of turbos :wink:
Kimmo / alfatune.fi
User avatar
Barry
Verde
Verde
Posts: 1993
Joined: Sat Nov 27, 2004 1:21 am

Post by Barry » Sat Aug 26, 2006 10:56 pm

kterkkila wrote:
Barry wrote:Forget the valve train.....How is this thing going to breath for 10000rpm.... :?
With a pair of turbos :wink:
YEA!! 8)
patzo_3l
Platinum
Platinum
Posts: 223
Joined: Mon Jan 31, 2005 5:59 am
Location: melbourne, australia.

Post by patzo_3l » Sun Aug 27, 2006 1:17 am

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.
patzo_3l

3l gtv6 turbo 85'
2006 147 gta selespeed
1990 75 twinspark
1998 spider
2.0l gtv 85'
33 1.7ie
hagen111
Silver
Silver
Posts: 4
Joined: Mon Aug 21, 2006 2:20 pm
Location: Houten - Netherlands
Contact:

Post by hagen111 » Sun Aug 27, 2006 2:01 pm

patzo_3l wrote: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?
Alfetta Sedan V6
75 Milano TS Ring Racer
Giulia Squadra Bianca
'67 GT(A) Replica
Post Reply