Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > 1- Porsche Technical Forums > 911 Engine Rebuilding Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Join Date: Jan 2005
Location: Gamlingay (Cambs) in UK
Posts: 133
2.7 RS spec power delivery

Hi

We have just rebuilt a 2.7 litre to RS specification. It has a competition valve job, the cases have been boat tailed, flywheel lightened, compression bumped to 9.3:1. Other than that it is faithful to the original '73 spec. However now it is run in I must say I'm mildly disappointed by the way it delivers the power.
It comes on really strong in the mid range but runs out of steam at the top end. At 2,500 - 3,000 rpm it has fantastic throttle response, lots of low down grunt. Coming out of the corners it is fantastic. However it tails off beyond 5000 rpm. Holding onto it beyond 5,500 seems pointless, better to change up and let the mid range torque do its work. Only trouble is I like engines that like to rev. Having not driven this type of engine before I am not familiar with the way it should drive.
So my question is are they all like this or should it pull like a train all the way to the red line? If the latter it might indicate a fault(s). If so any pointers as to what that might be please

Thanks,

Keith.
__________________
carreraplanes
Old 10-21-2005, 04:14 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
Join Date: Jul 2001
Location: Highlands Ranch, CO
Posts: 238
Wow, you should be getting some more pull all the way up.

I have a 73E rebuilt to 2.7, 9.5:1 compression and it pulls hard all the way up to 7 grand. You should start with the basics:

Timing? Is it advancing correctly? No rev limiter on your rotor?

Cams? You didn't mention but are they S spec? Timed right?

Fuel/air? You don't mention MFI? If so is the pump working right? Rebuilt to RS specs? Throttle bodies the right size?

Good luck, you should have a hell of an engine.
__________________
Fritz
1987 944S
1973 911E
Old 10-21-2005, 05:14 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
drag racing the short bus
 
dd74's Avatar
 
Join Date: May 2002
Location: Location, Location...
Posts: 21,980
Yes, it should develop power past 5500. But then again, true RS Spec engines redlined at 6,300 RPM, I believe.
__________________
The Terror of Tiny Town
Old 10-21-2005, 07:10 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
Join Date: Sep 2002
Location: France
Posts: 628
you mean 7300?
Old 10-22-2005, 02:07 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
Join Date: Jan 2005
Location: Gamlingay (Cambs) in UK
Posts: 133
Quote:
Originally posted by Fritz
Wow, you should be getting some more pull all the way up.

I have a 73E rebuilt to 2.7, 9.5:1 compression and it pulls hard all the way up to 7 grand. You should start with the basics:

Timing? Is it advancing correctly? No rev limiter on your rotor?

Cams? You didn't mention but are they S spec? Timed right?

Fuel/air? You don't mention MFI? If so is the pump working right? Rebuilt to RS specs? Throttle bodies the right size?

Good luck, you should have a hell of an engine.
Thanks. The engine is a european 210 carrrera from 1974. This is exactly the same as the RS 1973 unit. So it has 'S' cams, MFI, correct throttle bodies, etc. The rev limiter is built into the rotor arm and is the RS unit.

Think I'll go through the basics. Just need to check out the way these should actually be so I'm not chasing a problem that does not exist.


Keith.
__________________
carreraplanes
Old 10-22-2005, 05:47 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
Join Date: Jan 2002
Posts: 604
When I bought my car, way back when, it came with a 2.7RS spec motor. It had a power curve exactly as you stated. Great throttle response from the mechanical injection, but something was definitely missing from the top end. Not that it was slow, (I still remember pulling on one of those twin turbo Z's. The look on the guys face was priceless), but it was lacking a solid push above 5,500 RPM. It would just kind of rev in that range, not really come alive.

When it started to leak a larger than normal amount of oil due to a pulled head stud, I pulled it apart. I discovered the prior owner had taken a few short cuts to obtain "RS" spec. Apparently he just added the P/Cs and left everything else the original standard "E" spec of the core motor with the exception of "S" cams. The heads were not ported or fly cut and the injection system was standard "E".

I reasoned that was the source of my missing "spike" in the power curve above 5,500.

I have since moved on to a bigger motor, but I have all the pieces machined and waiting in the garage for assembly. I just have not had the time to confirm if my hypothesis is correct.

Tinker
Old 10-22-2005, 10:48 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Registered User
 
Join Date: May 2003
Posts: 3,213
I run a MFI 2.7 RS replica motor in my race car. It is exact including 8.5 compression ratio. I shift at 7300 RPM because I hit the rev limit not because it's not pulling. I wish I could take it to 7500 plus but I don't have race valve springs and I want the engine to last awhile.

Something is wrong with your engine.

-Andy
__________________
72 Carrera RS replica, Spec 911 racer
Old 10-22-2005, 08:32 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
Join Date: Jan 2005
Location: Gamlingay (Cambs) in UK
Posts: 133
Thanks for your interest. I think I may have found the root of the problem. I checked the timing marks on the crankshaft pulley. They are marked as 30 and 32 degrees. According to Wayne's book it should be 38 @ 6000 rpm. 6 degrees retarded by the looks of it. This is probably where the power is going. I also checked the part number on the distributor. It is 0231 184 004. Will check that that is the correct item too.
__________________
carreraplanes
Old 10-23-2005, 02:44 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Try not, Do or Do not
 
Henry Schmidt's Avatar
 
Join Date: Apr 2004
Location: Fallbrook, Ca. 92028
Posts: 5,934
Garage
I would suspect ignition or MFI pump timing.
We recently had an MFI engine that was making us crazy. We went through a plethora of engine tune up possibilities and then did it again without success.
After literally months of anguish we took the engine out to discover that the MFI drive pulley on the cam had come loose and the mounting holes had gotten oblong so the pump timing was constantly changing.
This engine had a high rpm miss but your problem (lack of high rpm power) may be pump timing.
Good luck
__________________
Henry Schmidt
SUPERTEC PERFORMANCE
Ph: 760-728-3062
Email: supertec1@earthlink.net
Old 10-23-2005, 10:12 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Author of "101 Projects"
 
Wayne 962's Avatar
Quote:
Originally posted by carreraplanes
Thanks for your interest. I think I may have found the root of the problem. I checked the timing marks on the crankshaft pulley. They are marked as 30 and 32 degrees. According to Wayne's book it should be 38 @ 6000 rpm. 6 degrees retarded by the looks of it. This is probably where the power is going. I also checked the part number on the distributor. It is 0231 184 004. Will check that that is the correct item too.
I think you're onto the source of the problem. I just tracked down a whole host of problems with my own car last year, and the solution: rebuild distributor. Putting a timing light on the distributor revealed spotty triggering of the spark - this wasn't apparent until the new one was in there, and was "spot-on" compared to the old one.

Also, be sure to check total advance. This is very important - if the weights in your distributor aren't advancing enough, you will rob yourself of power on the top end. I explain the procedure for timing and checking this in both the Engine Rebuild Book, and the 101 Projects Book...

Just from memory, 004 is the correct distributor. I think we sell Bosch factory rebuilt ones for $350 or somewhere in that range.

-Wayne
__________________
Wayne R. Dempsey, Founder, Pelican Parts Inc., and Author of:
101 Projects for Your BMW 3-Series 101 Projects for Your Porsche 911 How to Rebuild & Modify Porsche 911 Engines 101 Projects for Your Porsche Boxster & Cayman 101 Projects for Your Porsche 996 / 997
Coming Soon:
SPEED READ: Porsche 911 (October 2018)
Old 10-24-2005, 04:24 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Registered User
 
skinnerd's Avatar
 
Join Date: Aug 2001
Location: Portland, OR USA & Bangkok, Thailand 50/50
Posts: 2,490
Garage
yes....there is something wrong
my RS spec 2.7 MFI always pulled hard to 7400-7500 with no issues
from 3000 on up, it was hold on and smile
__________________
"Are you out of your Vulcan mind?"

Doug
1973 RSR inspired genesis powr'd by dilithium crystals (3.6 RS Vram)
Old 10-24-2005, 10:09 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Registered User
 
GrantG's Avatar
 
Join Date: Jan 2005
Location: Denver, CO
Posts: 958
Garage
Yep, they should pull hard well beyond 7k...
__________________
16 Cayman GT4, 73 Carrera RS 2.7 Carbon Fiber Replica (240hp & 1,890 lbs), 06 Evo IX w/ Ohlins DA's, Brembo 6-piston, E85 tune (415hp)
Former: 73 911S, Two 951S's, 996 C2, 993 C2, BMW 635CSi Euro, Ferrari 550 Maranello
Old 10-24-2005, 12:13 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
drag racing the short bus
 
dd74's Avatar
 
Join Date: May 2002
Location: Location, Location...
Posts: 21,980
Quote:
Originally posted by skinnerd
yes....there is something wrong
my RS spec 2.7 MFI always pulled hard to 7400-7500 with no issues
from 3000 on up, it was hold on and smile
Was that engine in a different car? The car you have now has a 3.2? What happened to the RS spec 2.7?
__________________
The Terror of Tiny Town
Old 10-24-2005, 12:50 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Registered User
 
KobaltBlau's Avatar
 
Join Date: Mar 2004
Location: City of Seattle, WA
Posts: 3,374
Quote:
Originally posted by GrantG
Yep, they should pull hard well beyond 7k...
especially in an 1890lb 911
__________________
Andy
Old 10-24-2005, 01:49 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)
Registered User
 
GrantG's Avatar
 
Join Date: Jan 2005
Location: Denver, CO
Posts: 958
Garage
Quote:
Originally posted by KobaltBlau
especially in an 1890lb 911
Andy - where do you drive around Denver? Maybe we should do a trackday or mountain drive sometime
__________________
16 Cayman GT4, 73 Carrera RS 2.7 Carbon Fiber Replica (240hp & 1,890 lbs), 06 Evo IX w/ Ohlins DA's, Brembo 6-piston, E85 tune (415hp)
Former: 73 911S, Two 951S's, 996 C2, 993 C2, BMW 635CSi Euro, Ferrari 550 Maranello
Old 10-24-2005, 02:11 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #15 (permalink)
Registered User
 
Join Date: Jul 2000
Location: So. Calif.
Posts: 18,187
I'd hate someone to overlook this. Many engines are running around with the throttle linkage set up to deliver less than WOT. Check at pedal and at the throttle bodies.

Sherwood
Old 10-24-2005, 04:37 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #16 (permalink)
Author of "101 Projects"
 
Wayne 962's Avatar
Quote:
Originally posted by 911pcars
I'd hate someone to overlook this. Many engines are running around with the throttle linkage set up to deliver less than WOT. Check at pedal and at the throttle bodies.

Sherwood
Good thinking. Sometimes the best solution is the most obvious!

-Wayne
__________________
Wayne R. Dempsey, Founder, Pelican Parts Inc., and Author of:
101 Projects for Your BMW 3-Series 101 Projects for Your Porsche 911 How to Rebuild & Modify Porsche 911 Engines 101 Projects for Your Porsche Boxster & Cayman 101 Projects for Your Porsche 996 / 997
Coming Soon:
SPEED READ: Porsche 911 (October 2018)
Old 10-24-2005, 08:39 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #17 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 06:53 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.