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914World.com _ 914World Garage _ Best Overall 911 engine

Posted by: bd1308 Sep 3 2005, 10:08 PM

first, how is cooling with these cars? Do these engines drop valve seats like the t4 does?

second, which engine is considered a good buy ( not too much, widely available, and reliable)

i'm just gathering information for what will eventually be a transplant...

Posted by: URY914 Sep 3 2005, 10:24 PM

Here we go again....

Posted by: Mueller Sep 4 2005, 12:36 AM

QUOTE (bd1308 @ Sep 3 2005, 09:08 PM)
first, how is cooling with these cars? Do these engines drop valve seats like the t4 does?

second, which engine is considered a good buy ( not too much, widely available, and reliable)

i'm just gathering information for what will eventually be a transplant...

they kept getting better thru the years, so you want the latest model you can afford with the least amount of miles....

Posted by: redshift Sep 4 2005, 12:57 AM

3.2 stroker with MFI.

M

Posted by: Jeroen Sep 4 2005, 05:46 AM

I don't think I ever heard about a 911 engine dropping valve seats

In a nutshell...

2.4 and smaller... watch for general wear, these engines are getting old

2.7 - known for pulled head studs

3.0 SC - pretty much bullet proof (bottom end of the 911 turbo), although lately, I've heard of a few with pulled headstuds as well

3.2 - same bottom end as the 3.0, but watch for valveguide wear comes with EFI and hydraulic chain tensioners

3.6 - early versions (up to 91 IIRC) are known to have oil leakage trouble at the cilinderbase (requires a full teardown to fix)

Keep in mind that rebuilding a 2.0 costs about as much as rebuilding a 3.6

Posted by: ArtechnikA Sep 4 2005, 06:09 AM

QUOTE (bd1308 @ Sep 4 2005, 12:08 AM)
first, how is cooling with these cars?
Do these engines drop valve seats like the t4 does?
second, which engine is considered a good buy ( not too much, widely available, and reliable)

fine; over about 200HP you'll need a front oil cooler.
no.
they are all reliable.
i'd hold out for an aluminum-case 2,8RSR with high-butterfly injection.
but for the criteria you mentioned, it's hard to beat the 3,0 SC.

Posted by: TimT Sep 4 2005, 06:15 AM

best overall 911 engine?

they would be the few that I built

Posted by: Aaron Cox Sep 4 2005, 12:27 PM

britt, i think you need a CA 75/76 2.7 motor with thermal reactors

Posted by: bd1308 Sep 4 2005, 08:01 PM

aaron:

if i've learned one thing on this board, i've learned that thermal reactors placed on 911 engines was one of the worst ideas ever...led to mucho uber heat in the engine compartment that subsequently led to engines with reduced life-spans.

Posted by: zymurgist Sep 5 2005, 07:08 AM

Didn't they also combine the thermal reactors with a 7 blade engine fan that moved less air around the engine? Those motors were designed to have a short life due to excessive heat.

Posted by: redshift Sep 5 2005, 07:13 AM

Well, who got Rudy's motor? (Otto's 3.HOLYSHIT RSR)

That is the motor you want, and I have connections.

M

Posted by: ArtechnikA Sep 5 2005, 07:19 AM

QUOTE (zymurgist @ Sep 5 2005, 09:08 AM)
Didn't they also combine the thermal reactors with a 7 blade engine fan that moved less air around the engine? Those motors were designed to have a short life due to excessive heat.

5. i have one, purchased at a ridiculously low price (especially compared to the cost of a new 11-blade fan) to replace the OEM fan on my 2,2 that had its drive hub chewed up by DAPO's use of too few adjustment shims...

i believe that in combination with the proper crankshaft pulley (there are at least 3 ratios from which to choose) that it will provide adequate cooling, require less power to run, and increase alternator speed for more power at low rpm. i haven't tested it tho, so i advise caution if contemplating this. however, there are a LOT of 5-blade fans sitting in people's spares piles...

i don't agree they were designed tohave a short life, but i agree that was the reasonably foreseeable consequence of the other design decisions.

BTW - only CA cars had the worst-case combinations of fan, reactore, and other stuff (EGR? air pump?). this was the era of the CA + 49-State car.

the engine i'm retrofitting into my '71 is a 49-state '75 2,7S; it has an 11-blade fan, no sign of air injection, and AFAIK (short exhaust port studs) no thermal reactors. since that was 30 years and at least one rebuild ago, some of these things could have been changed, of course...

i haven't decided what fan i'll run it with...

Posted by: Jeroen Sep 5 2005, 07:30 AM

from what I learned, the 5 blade fan moves just as much air as the 11 blade fan
the reason they went back to 11 blade is that the 5 blade is more noisy

Posted by: ArtechnikA Sep 5 2005, 07:41 AM

i'd need to see your source on that one, especially since they went back to the 11-blade fan for the cat cars (in the face of increasingly stringent noise regulations). they did play around with pulley ratios a lot.

Posted by: Sammy Sep 5 2005, 09:08 AM

3 liter with the dilavar lower head studs replaced with steel.
Bulletproof and in most cases good for several hundred thousand miles.

Posted by: Jeroen Sep 5 2005, 09:22 AM

QUOTE (ArtechnikA @ Sep 5 2005, 02:41 PM)
i'd need to see your source on that one

IIRC, it was quoted from Paul Frere's book on the Bird BBS

Posted by: airsix Sep 5 2005, 04:10 PM

Best 911 engine? I'd have to go with the GT-1 derived engine in the current GT3.

-Ben M.

Posted by: jd74914 Sep 5 2005, 06:48 PM

2.2S most power per lter from the factory

Posted by: Aaron Cox Sep 5 2005, 07:04 PM

QUOTE (jd74914 @ Sep 5 2005, 05:48 PM)
2.2S most power per lter from the factory

906 motor...
220 HP from 2L

Posted by: Maltese Falcon Sep 5 2005, 07:31 PM

Hey, don't bash thermal reactors ('75-'77 2.7's) the reactor replacement (shorty headers) made me beaucoup rich in the late '70s
The best 911 engine , and coolest running is this one --my CHT's dropped 75 f --top fan VS front fan.
Marty

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