2.5 or 2.6 - Page 3

blue72s · 02-18-2005, 12:23 PM

Yes the 2.8 short stroke is very nice and I believe there'll not be much difference between the 2.6 and the 2.8 short stroke. The advantage of the 2.6 is you can use a lightweight mag case whereas with a 2.8 you can't. For me, lightweight engine is important.

BURN-BROS · 02-18-2005, 12:33 PM

Actually the 2.8 is the highest recommended displacement for a mag case. It's one of the reasons why it is a popular choice.

Shuie · 02-18-2005, 12:39 PM

2.8 short stroke (95mmx66mm) is built on a early 3.0 case with the smaller bearing journals (930/02 or 930/52). Henry has posted some good stuff about this engine config before. Grady's 2.8 is 92mmx70.4 and 11+:1. either way, a 2.8 sounds like a lot of fun.

BURN-BROS · 02-18-2005, 12:45 PM

Just for the record, and to set the record straight

I did a quick search;

"For lightweight high performance a 2.8S built on a 7R case, twin plug, 10.3:1 CR will give you ~250 HP with good reliability."

"The advantage of starting with a 3.0 is that it is more robust and you can get to 3.5 and larger. It is a somewhat heavier engine."

Best,
Grady

kenikh · 02-18-2005, 12:55 PM

Quote:

Originally posted by blue72s
Yes the 2.8 short stroke is very nice and I believe there'll not be much difference between the 2.6 and the 2.8 short stroke. The advantage of the 2.6 is you can use a lightweight mag case whereas with a 2.8 you can't. For me, lightweight engine is important.

After searching the archives, I am unable to find weight differentials between the different case flavors. How much lighter is a mag case vs. early sandcast vs. 3.0L vs 964? I hear "lighter", but am curious as to how much.

Any pointers?

blue72s · 02-18-2005, 01:07 PM

Yes I know the 2.8 is the highest recommended for a mag case but this thread is about short stroke (66mm).

Weight difference between mag and alu is 22 Lbs. BIG difference.

kenikh · 02-18-2005, 01:09 PM

Quote:

Originally posted by blue72s
Yes I know the 2.8 is the highest recommended for a mag case but this thread is about short stroke (66mm).

Weight difference between mag and alu is 22 Lbs. BIG difference.

Yes indeed. Thanks!

BURN-BROS · 02-18-2005, 01:23 PM

Thanks for the correction, that is true.

Cupcar · Cupcar's Garage

I would think a short stroke 2.6 could easily be made to do more than 260 HP.

I built a short stroke "2338 cc" which was 86.7 mm Mahle 2.5 pistons on a 66 instead of a 70.4 crank for 9.8:1 CR, GE80 cams, 46X40 valves, 36X35 ports, single plug, 40 IDA w/36 mm venturis.

Made 237 HP at 7400 RPM on dyno. A little over 100 HP/ liter.

I would think 100 HP/liter easy with 2.6 as well.

Shaun @ Tru6 · 03-27-2005, 04:59 PM

hi Everyone, just found this thread in researching a motor I may build.

I've got an opportunity to trade my tired but good 3.2 wtih 241K miles on it for a set of (from his ad):

"Brand-new, NOS, never-installed original 2.5ST Longstroke 86.7mm Pistons/Cylinders from Mahle! 10.3:1, forged pistons, Nikasil cylinders. Makes a "2.4" (2341cc) into a 2.5L (2494cc). Uses the 70.4mm crank usually. Sure, you can use the 66mm crank as well (2.0/2.2-->~2335cc). Very unique upgrade, extremely rare! Out of production for several years (NLA). Includes new GOETZ rings (impossible to get for these pistons), new clips, new pins. All in original Mahle wax paper, in perfect original Mahle boxes. "

Pretty broad question, but what am I getting myself into? this engine would go in my 69E. I imagine picking up a 2.4 case and 70.4mm crank.

With proper machine work, can I use my E's heads? MFI rebuilt to match the 2.5 needs?

what can I reasonably expect in terms of power if a proper motor is built around these P/C's?

Thanks for your help!

rotorhead · 03-27-2005, 05:17 PM

There is a 911S case on ebay at the moment and the price looks very good

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7963708156&category=33613

Steve

BURN-BROS · 03-28-2005, 05:44 AM

Those pistonsand cylinders are/were being sold by YTNUKLR. He is a pelican.

Shaun @ Tru6 · 03-28-2005, 06:23 AM

Quote:

Originally posted by BURN-BROS
Those pistonsand cylinders are/were being sold by YTNUKLR. He is a pelican.

yes, thanks, Scott and I have been going back and forth quite a lot. I was hoping to get a third party opinion on what to do with these, what kind of motor they would make, etc.