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 > Porsche Forums > 911 / 930 Turbo & Super Charging Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Join Date: Feb 2015
Posts: 130
1976 2.7 - Supercharger sir?

I have come by a really quite original 1976 CA 911s (smog pump, CSI, thermal reactors and air con) with original engine and trans that had a recorded total engine rebuild 5k miles ago (all be it in 2004) which runs smooth as a sewing machine and I'm looking at the engine bay and I'm thinking, thinking....

To get more power from the current, original set up, first off I'm considering binning the thermal reactors and heat providing headers and installing an SSI + sports exhaust, to let her breathe properly (smog pump already gone). I read that this engine is really quite special when stripped of the incumbrances and runs nice and cool with a carrera oil cooler set up, esp with ribbed oil tubes and then has that 'rasp' we all covet.

I'm looking at the air con setup and I'm thinking that to get more power, rather than strip the engine down again and breathe on it (Lots of money?), could it be an idea, to simply replace the air con pump with a supercharger, which could then easily be removed in the future to put the engine back to stock?

I know Paxton's have been fitted to 3.2's before, but a 2.7? well, why not? I'm also thinking Eaton superchargers which can be had second hand from small Mercedes engines. cheap as chips over here in the UK ($200).

I guess I'm really considering Bangs for Bucks

Any thoughts anyone please?


Old 06-26-2020, 02:44 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Grappler
 
Rodsrsr's Avatar
 
Join Date: Jul 2006
Posts: 4,775
Garage
I don't think I would recommend that on a 2.7....pretty sure those are prone to pulling head suds normally aspirated. Others may chime in...
__________________
Grappler
Know Gi / No Gi

1976 RSR Backdate (Turbo 3.2)
Old 06-26-2020, 10:03 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered User
 
Join Date: Oct 2010
Posts: 13
Not sure about the 2.7 but here is a data point regarding HP potential:

3.0 SC with Paxton SN2000HO- custom built kit not from SOK
964 Cams
Haltech stand alone efi
Custom fab intake using 70mm Ford throttle body
8.9:1 static compression - custom JE pistons with ductile rings
ARP head studs and rod bolts
Long tube headers and custom exhaust

270whp at .61 bar (9 psi) blowing thru a modified 930 intercooler. This was a serpentine belt set set up using Ford belt tensioner and idler pulley.

We converted to turbo so removed from car. I still have the Paxton head unit, stainless mounting bracket to get it on the motor and the tensioners. All other parts to complete are not available.

Willing to sell for $600. PM if you have interest.
Note: you will need to have a serpentine crank pulley machined, A/C pulley modified for serpentine belt, plus get it plumb to the throttle body.
Old 06-29-2020, 03:46 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered
 
cmcfaul's Avatar
 
Join Date: Feb 2003
Posts: 1,774
Garage
Send a message via AIM to cmcfaul Send a message via Yahoo to cmcfaul Send a message via Skype™ to cmcfaul
On the rebuild sheet did they add case savers? There like timecerts that hold the head studs more securely into the block. As mentioned earlier, the 2.7 weakness was a propensity to pull the head studs from the case or to break them, particularly if they are Delvar. It's standard procedure to replace Delvar during a rebuild with steel. If the head studs were not replace and case savers not used, no way I would put any more stress on this engine. Heat cycles associated with the thermal reactors make the magnesium more brittle. Taking all that stuff off (Thermal reactor, air pump, ac (if not working)) is a great place to start.

Chris
73 E 2.4
Old 06-30-2020, 01:18 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
angelny911's Avatar
 
Join Date: Feb 2005
Location: New York.NY
Posts: 328
I have a sok setup for a 3.0 motor
__________________
pca 30 year member,1977 porsche turbo body targa
56 vw ragtop oval
01 harley sportster
18 Chevy Colorado diesel
BIG RED Firetruck and assorted v-dub ,porsche parts hoarder..LoL

Last edited by angelny911; 06-30-2020 at 05:30 PM.. Reason: Spelling
Old 06-30-2020, 05:29 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered
 
Join Date: Dec 2009
Location: San Jose
Posts: 197
Garage
Depends on what you want out of the driving experience. Might be a better path to lighten the car and optimize the motor in N/A form. There have been some turbo 2.7 set ups done successfully. Never seen a supercharged one.
Old 06-30-2020, 05:31 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Registered User
 
Join Date: Feb 2015
Posts: 130
SC'd 2.7

Thanks for the feedback.

I've found these 2 articles which makes interesting reading:

Supercharging a 2.7

supercharging an SC

I'm pretty confident I could make up the necessary parts but if I need an EFI and ECU then its going to start getting quite expensive, plus the additional unknown of whether a 2.7 mag case will be able to handle that extra power once its all done.

Another thought, if I'm looking at an already wheezy 2.7, I wonder whether I need all the cost of 4 or 6 rib drive belts and pulleys and tensioners. Would using just a simple standard v belt with the drive taken off the existing air con pulley, with no tensioners, work (with a suitable ratio pulley on the S.C.)?

If the belt did start to slip at higher rpm then this may be a bonus in preventing the S.C from generating too much boost at higher revs.
Old 07-02-2020, 12:02 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered
 
cmcfaul's Avatar
 
Join Date: Feb 2003
Posts: 1,774
Garage
Send a message via AIM to cmcfaul Send a message via Yahoo to cmcfaul Send a message via Skype™ to cmcfaul
The 2.7 is the worst engine to put forced injection on. Will need major mods to the case. One with a thermal reactor on it for so long makes me think it just won't hold. Too many heat cycles in a weak mag case. The SC is a much better engine to start with.
Old 07-03-2020, 05:08 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Registered User
 
Join Date: Oct 2010
Posts: 13
The 2.7 is not the best base to modify. That said, a V belt set-up will limit boost to around 4 psi. The effective compression ratio (CR at peak boost) will be 10.8:1 assuming your static CR is still factory 8.5. For comparison, the effective CR on my SC is 17.8:1 at 1 bar.

At 4 psi, consider if it is worth the effort/cost/risk. Estimate 20% power gain (5% per 1 lb boost). Considering a stock 76 made 165hp, estimate 200-205 flywheel hp SC with improved torque. Increase weight will mitigate the power gain. The Paxton head unit and mounting bracket weigh 28 lbs plus add in the weight or a tea tray wing. I would be concerned with the look of the the tea tray spoiler if you have less than SC flares. I changed the rubber to 3.2 Carrera to help with the proportion. If it was me, I would build a hotter 2.7 NA motor and take weight out of the car as previously suggested.
Old 07-03-2020, 07:25 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Registered User
 
Join Date: Feb 2015
Posts: 130
76 s.c

All good points, a lot to think about.

Thanks to everyone who has input.

Old 07-03-2020, 10:48 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 02:12 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2020 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.