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 Rating: Thread Rating: 4 votes, 4.00 average.
Author
Thread Post New Thread    Reply
Registered User
 
DA VINCI's Avatar
 
Join Date: Aug 2010
Location: Spain
Posts: 39
Thierry, thanks for your answer.

More...

How did you measure detonation on this car?

And, what is the exact boost pressure and rpm at max power with the 500HP set up?

Last edited by DA VINCI; 12-22-2011 at 09:59 AM..
Old 12-22-2011, 09:56 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #201 (permalink)
Registered User
 
Join Date: Feb 2009
Location: FRANCE (Besanšon)
Posts: 310
Quote:
Originally Posted by DA VINCI View Post
Thierry, thanks for your answer.

More...

How did you measure detonation on this car?

And, what is the exact boost pressure and rpm at max power with the 500HP set up?

As you can see on my last measurements, the max HP is obtained @ 5300 rpm with 1.35 bar.

Regarding the knocking, I verified it via a knock sensor (piezo) + oscilloscope while I went to dyno. But you know educated human ears are a wonderful instruments either.
__________________
965 C2T / 1991 3.3 TURBO
Old 12-22-2011, 01:30 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #202 (permalink)
Registered User
 
DA VINCI's Avatar
 
Join Date: Aug 2010
Location: Spain
Posts: 39
67 kgm at max power!... that thing pushes for sure!

Where have you fitted the sensor/s on the dyno? This is one of my great concerns about this engine, I cant find the right place (we dont have the protuberances on the cylinders to mount a bridge that connects them to the knock sensor as on the 993TT).

Last edited by DA VINCI; 12-26-2011 at 02:14 PM..
Old 12-22-2011, 02:46 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #203 (permalink)
Metal Guru
 
911nut's Avatar
 
Join Date: May 2001
Location: Michigan
Posts: 2,511
Garage
Quote:
Originally Posted by Thierry25 View Post
Considering the stock static compression ratio & stock dynamic CR, the 95 euro fuel compatibility ( we have 98 available everywhere here) and the huge margin the factory apply , I decided to install the FVD ignition sensor plate. This plate increase advance by +6░. Thus from 21░ max , the advance timing curve is pushed to 27░ max.
To give some idea about the results, with my SC cams , my hybrid K27/29 turbo and under 1.2b boost pressure @max TQ point, the +6░ ignition advance increase the torque by about 3-4 mkg @ max TQ point ! Interesting efficiency gain!
Thierry,
I don't think that 21 degrees is all that conservative for a stock engine.

Optimal timing for any engine ends up being in a small window.

Let's think about why the extra 6 degrees of timing advance works well on your engine.

This could be explained by relative amounts of charge density between an engine with no-overlap cams and and an engine with big duration cams having some overlap, with the related combustion speed effects.

On a 3.3 Turbo engine with stock cams having no overlap, there is no reversion of exhaust gases diluting the mixture. The combustion flame front will proceed rapidly across the chamber and above a certain rpm the factory determined that 21 degrees advance is optimal.

On your engine, your cams have a longer duration than stock and therefore I'm assuming, have some overlap. As the piston approaches TDC, both intake and exhaust valves are open, which allows a fraction of exhaust gases to be forced into the intake on the upstroke before the piston begins to travel downward on the intake stroke. A diluted charge will take longer to burn so more advance is required (as engine speed increases the charge must be ignited sooner as the flame front propagation speed is fixed for discreet levels of charge density and atomization) to optimize the combustion and take advantage of the extra charge that higher durations cams allow.

Seeing as how the reversion has a greater impact on efficiency at low engine speeds (since the engine is operating as a n/a engine before reasonable levels of boost are achieved) and atomization of the mixture is better under boost, I'm wondering if you could get a little more torque if you could revert to stock timing at say, above 5000 rpm? (another option is to stay at 3 degrees of extra advance to the redline). I know that's not possible with the EZ 69 but Megasquirt 1 could be the answer

As for me, there's no benefit (and perhaps some risk if I did) to change timing until I install hotter cams myself (which will be soon, hopefully )
__________________
Paul B.
'91 964 Turbo
Port matched, SC cams, K27/K29 turbo, Roush Performance custom headers w/Tial MV-S dual wastegates, Rarlyl8 muffler, LWFW, GT2 clutch & PP, BL wur, factory RS shifter, RS mounts, FVD timing mod, Big Reds, - 210 lb
Old 12-26-2011, 10:52 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #204 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 07:46 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, 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.