Go Back   986 Forum - The Community for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Boxster General Discussions

Post Reply
 
LinkBack Thread Tools Display Modes
Old 11-27-2006, 07:15 PM   #21
Porsche "Purist"
 
Paul's Avatar
 
Join Date: Aug 2003
Location: Wisconsin
Posts: 2,123
Garage
A turbo converts waste heat into energy to drive a compressor, so it is more efficient. If you don't believe this, measure the temperature of the exhaust gas before and after the turbine.

__________________
1998 Boxster with 7.8 DME, 2005 3.6 liter/325 hp, Variocam Plus, 996 Instrument panel
2001 Boxster original owner. I installed used motor at 89k.
1987 924S. 2002 996TT. PST-2
Owned and repaired Porsches since 1974. Porsche: It's not driving, it's therapy.
Paul is offline   Reply With Quote
Old 11-27-2006, 07:54 PM   #22
Registered User
 
Join Date: Apr 2006
Location: Seattle
Posts: 170
Quote:
Originally Posted by JP-s-in st. louis
I have more plans not this motor but since I like this car so much and it is all but paid off. I hope to find a 3.2 or 3.4 sleeve it out to a 4.1 (alla Todd) do some head work and tune via IA, Tit connecting rods, pistons, Cams and and some N20... I figure I like this car that much and am already knee deep. So anyone who has a line on an engine please keep me in the know...

I will eventually do a wide body kit like an RSR so I can fit bigger meats under it. I already have issues hooking up. 1st is useless and 2nd is almost the same.

Now that's what I'm talking about. Making the car a blast to drive. Hell, I'm deep into mine already, so what's a little more $$$. I think I will keep mine around for the race/show vehicle but mod the crap our of it.

Josh, let's go take your car out in the snow. Let's have some fun. You said I can drive it anytime, I'll be over in 30 minutes.

-David
__________________
1996 993TT - current

2001 Boxster S (sold)
19" SSR GT3 - Cross coilovers - Custom Magnaflow exhaust - B&M Short Shifter - EVO intake - GT3 Seats - Hardtop

http://www.emeraldcitycustoms.com/images/box2.jpg

1986 Carrera (sold)
David_J is offline   Reply With Quote
Old 11-27-2006, 08:55 PM   #23
Registered User
 
Join Date: Sep 2005
Location: Minneapolis/St. Paul, Minnesota, USA
Posts: 3,308
Hi,

A Super is Crank Speed dependent ± the Pulley used. Power comes sooner, little spool up time (lag). But, it loses something at the top end over a Turbo due to parasitic loss (you need more boost from a Super to achieve the same HP). Roots type are less efficient than the compressors in a Turbo. Vane type are about the same as a Turbo.

A Turbo comes on later (lag), but creates more power higher in the Tach with less Boost. More complex plumbing and Oil circuit (most Supers use a self-cotained Oil System). Heat Management becomes an issue, especially on a mid-engine.

I'm not yet convinced of using either on the Boxster w/o Intercooling due to the high CR and variability of available fuel. I'm skeptical of the longevity of a Boosted M96 engine. There are few high-mileage examples, so it is yet to be proven to my mind.

But, for simplicity, the Super kits are the better of the two for the Boxster IMHO...

Happy Motoring!... Jim'99
MNBoxster is offline   Reply With Quote
Old 11-28-2006, 05:43 AM   #24
Registered User
 
Join Date: Feb 2005
Location: Seattle is now home!
Posts: 398
Quote:
Originally Posted by David_J
Now that's what I'm talking about. Making the car a blast to drive. Hell, I'm deep into mine already, so what's a little more $$$. I think I will keep mine around for the race/show vehicle but mod the crap our of it.

Josh, let's go take your car out in the snow. Let's have some fun. You said I can drive it anytime, I'll be over in 30 minutes.

-David
I can spin the tires thru 3 in the rain and you want me to go out in snow...hahahahaha

I would not even make it up the hill on my street.
__________________
Everything is for sale

3.6, SC 'er and other parts for sale
JP-s-in st. louis is offline   Reply With Quote
Old 11-29-2006, 07:56 PM   #25
Registered User
 
Join Date: Apr 2006
Location: Chicago
Posts: 1,518
Quote:
Originally Posted by MNBoxster
Hi,

A Super is Crank Speed dependent ± the Pulley used. Power comes sooner, little spool up time (lag). But, it loses something at the top end over a Turbo due to parasitic loss (you need more boost from a Super to achieve the same HP). Roots type are less efficient than the compressors in a Turbo. Vane type are about the same as a Turbo.

A Turbo comes on later (lag), but creates more power higher in the Tach with less Boost. More complex plumbing and Oil circuit (most Supers use a self-cotained Oil System). Heat Management becomes an issue, especially on a mid-engine.

I'm not yet convinced of using either on the Boxster w/o Intercooling due to the high CR and variability of available fuel. I'm skeptical of the longevity of a Boosted M96 engine. There are few high-mileage examples, so it is yet to be proven to my mind.

But, for simplicity, the Super kits are the better of the two for the Boxster IMHO...

Happy Motoring!... Jim'99
Jim,

Found another thread about this subject :

turbo or supercharge ?

Look like your opinion hasn't changed much in the past year.

I am surprised you prefer the supercharger over the turbo for the Boxster, though...

Nick
__________________
*
http://i146.photobucket.com/albums/r...s/DSC03717.jpg

1999 986 ( Black )
1998 MB C280 ( Black )
1999 BMW K1200RS ( Yellow )
2005 Audi A4 ( Red )
NickCats is offline   Reply With Quote
Old 11-29-2006, 09:58 PM   #26
Registered User
 
Join Date: Sep 2005
Location: Minneapolis/St. Paul, Minnesota, USA
Posts: 3,308
Quote:
Originally Posted by NickCats
Jim,

Found another thread about this subject :

turbo or supercharge ?

Look like your opinion hasn't changed much in the past year.

I am surprised you prefer the supercharger over the turbo for the Boxster, though...

Nick
Hi,

Doesn't surprise me that my information (or opinion) hasn't changed at all. I have had a fair amount of experience with Forced Induction both in Aircraft and Automotive applications. Each has their advantages and disadvantages. But these are not generic, rather, they often depend upon the application.

With the Boxster, being mid-engined, I think the Heat Management issues alone (let alone the plumbing issues) would outweigh the advantages of a Turbo. So, I would most likely choose the Supercharger route.

That's not an endorsement, at least without Intercooling, or some other way to prevent detonation given the high CR that the Boxster has...

Happy Motoring!... Jim'99
MNBoxster is offline   Reply With Quote
Old 11-30-2006, 07:34 AM   #27
Registered User
 
Join Date: Feb 2006
Location: Poway, CA
Posts: 191
Trigem2k!

When you get your turbo set up, lets hook up and you can compair it to an NA 3.4l :dance:

If you will get 270 to the wheels, it should be close to mine. I am in San Diego and would love an excuse to get up there to drive some of the canyons in Malibu!!

If you guys are spending 7k for the kit, and 2k for install, why not just go with a 3.4 conversion, with no detonation potential, no real heat issues, and no worries about going to FI on a high CR motor?

Theres no way I would go to FI on with the CR the M96 has with no IC.

I have an eaton SC on my E36 318i with no IC and the CR is 10:1. And that is pushing it but it only gets up to 6 psi. But it kicks ass when a E36M3 can't pull on me in a little ol 318 :dance:

I would imagine that they tune the ECU to accomodate the additional fuel required to match the FI, for either system, right?
__________________
Arctic Silver 2000 Boxster 3.4l w/Sport Design Package
Supersprint Boxster S Headers/Cats/Muffler
AASCO Lt. Wt FLywheel
Evo Intake
Partial Carbon Interior
Black Leather Sport seats
M030 Sway Bars
Litronics w/ Clear Corners
Boxster S brakes
B&M Short Shifter
PnP rear Speakers + Amp
pecivil is offline   Reply With Quote
Old 11-30-2006, 08:03 AM   #28
Registered User
 
ohioboxster's Avatar
 
Join Date: Dec 2005
Location: Akron
Posts: 793
Yes Jim but what do you do if the car doesnt detonate? You know even when my car continues to run for trouble free mile after mile I have a feeling there are people that will say "Fluke" or "Lucky". I just dont understand why several people say the car will detonate due to the compression ration. I drive my car everyday without issue. Let me clarify, Im not looking for an endorsement or even convince you of anything but just want you be aware 5 lbs of boost does not make the car detonate.
__________________
2002 TT
ohioboxster is offline   Reply With Quote
Old 11-30-2006, 08:09 AM   #29
Registered User
 
Join Date: Apr 2006
Location: Seattle
Posts: 170
Upgrading a 3.2 to a 3.4 doesn't seem a logical choice for what you get. I mean, my 3.2 only has 24000 miles. Why would I want to upgrade that to a 3.4? Adding a SC to a 3.2 sounds like a good choice for me.

-David
__________________
1996 993TT - current

2001 Boxster S (sold)
19" SSR GT3 - Cross coilovers - Custom Magnaflow exhaust - B&M Short Shifter - EVO intake - GT3 Seats - Hardtop

http://www.emeraldcitycustoms.com/images/box2.jpg

1986 Carrera (sold)
David_J is offline   Reply With Quote
Old 11-30-2006, 08:39 AM   #30
Registered User
 
Join Date: Sep 2005
Location: Minneapolis/St. Paul, Minnesota, USA
Posts: 3,308
Quote:
Originally Posted by ohioboxster
Yes Jim but what do you do if the car doesnt detonate? You know even when my car continues to run for trouble free mile after mile I have a feeling there are people that will say "Fluke" or "Lucky". I just dont understand why several people say the car will detonate due to the compression ration. I drive my car everyday without issue. Let me clarify, Im not looking for an endorsement or even convince you of anything but just want you be aware 5 lbs of boost does not make the car detonate.
Hi,

I never said your car detonates. What I said was that at anything over 8.5:1 CR, detonation becomes a concern. At 11.7:1 CR, it becomes a major concern.

Your car may be detonating at certain times and you're unaware of it, it may be doing so under certain conditions (Ambient Temp, Load, Fuel Quality, etc.). The DME may be compensating for it by using a detuned MAP, I don't know, I haven't studied your specific installation and all it's pertinent parts and those of the motor itself. But, if you are at times detonating, it's probably not enough to grenade the engine, but what are the longterm effects?

The rule of thumb is that anything over 10:1 CR requires Intercooling to be safe from detonation. Porsche doesn't force the M96 engine in any of their cars, what do they know that we don't? The Turbo uses a different engine. The TT engine (M96/70) is similar to the M96, but also very different - 8.4:1 CR.

Adiabatic Heating (a Gas rises in Temp if it is compressed) raises the Charge Temp 11°/1 PSI (10.9°/1 PSI to be precise). So, at 5 PSI, your intake charge is 55° hotter than the Ambient Air entering the Intake. On a 60° day, this means a lot less than on a 98° day, because the Charge temp would be 115° on the 60° day, but 153° on the 98° one. This heated charge will reach a detonation threshold (approx. 268°) a lot sooner in the compression stroke (where it is further compressed and heated) than Ambient Air charge would, which is what the engine was designed for (Pistons, Bore, CR). This means the engine must produce a spark sooner to compensate. How much sooner is it capable of? I don't know. How soon is too soon? Again, I don't know. But, it's the not knowing which concerns me.

Also, one bad batch of fuel and you could have serious problems. That's just too much risk management for me I guess...

Happy Motoring!... Jim'99

Last edited by MNBoxster; 12-01-2006 at 07:47 AM.
MNBoxster is offline   Reply With Quote
Old 11-30-2006, 10:22 AM   #31
boggtown
Guest
 
Posts: n/a
Why dont we all cool down. I am a fun loving teenager who is popular and a practical joker, thats my personality. Others may be recluse, obnoxious, meticulous, or just plain grouchy, but thats who we are and we cant change that. The problem arises when 2 grouchy people get into it and gripe at each other, so when the person accuses the other of being grouchy, they themselves are grouchy. Its just a forum, chill out, words dont hurt anyone unless you choose to react to them. We are all smart people on this forum (cant say the same for the integra forum, lol) due to the fact we drive a boxster in the first place. We are all adults, lets act like it.
  Reply With Quote
Old 11-30-2006, 10:32 AM   #32
Registered User
 
Join Date: May 2006
Location: Northeast USA
Posts: 910
Quote:
Originally Posted by boggtown
Why dont we all cool down. I am a fun loving teenager who is popular and a practical joker, thats my personality. Others may be recluse, obnoxious, meticulous, or just plain grouchy, but thats who we are and we cant change that. The problem arises when 2 grouchy people get into it and gripe at each other, so when the person accuses the other of being grouchy, they themselves are grouchy. Its just a forum, chill out, words dont hurt anyone unless you choose to react to them. We are all smart people on this forum (cant say the same for the integra forum, lol) due to the fact we drive a boxster in the first place. We are all adults, lets act like it.
Sorry but I can't see what problem you are referring to. Personally, I enjoyed the information and opinions shared in this thread.
__________________
'06 Boxster S, 6sp, triple-black
http://i153.photobucket.com/albums/s...05_IMGcrop.jpg
z12358 is offline   Reply With Quote
Old 11-30-2006, 10:34 AM   #33
Registered User
 
ohioboxster's Avatar
 
Join Date: Dec 2005
Location: Akron
Posts: 793
Boggtown,
Jim and I have a difference in opinion and I dont believe we are out to hurt each others feelings. We have not made inflamatory comments to each other and I cant speak for Jim but Im not looking for a fight. If these comments were directed at us you are mistaken, if not disregard.
__________________
2002 TT
ohioboxster is offline   Reply With Quote
Old 11-30-2006, 10:46 AM   #34
boggtown
Guest
 
Posts: n/a
I am reffering to the entire forum, not a particular incidence, sometimes people can act a little strange sometimes. Im just trying to remind people that the more friends you have, the easier your life is. Life is your time spent with people you like and dislike, if you dont dislike anyone, your life will be much better. I just want you all to know your all my friends and if I take a long trip, I will try and stop by and say Hi to you all.
  Reply With Quote
Old 11-30-2006, 10:59 AM   #35
Registered User
 
Join Date: Feb 2006
Location: Poway, CA
Posts: 191
I think it is not a matter of like or dislike. People have differing opinions. These differing opinions differ because of the knowledge base they come from, and more knowledge is one main reason to visit a board like this.

While I have differed with Jim on one matter, I tend to think (based on his background) that he knows probably more than anybody on this board about what we speak to.

But that does not mean Ohio is bashing or unfriendly because he disagrees (or wrong for that matter).

But I too enjoy the exchanges on the board because it (hopefully) results in knowledge being spread about the Boxster, the car near and dear to all of our hearts.

So let the debating (friendly of course) rage, and let each state his facts.

but on the detonation issue, I am with Jim on this. Read this book called "Supercharger" written by Corky Bell, and you will understand much about how FI works in an engine. I have read it, and what Jim is saying is spot on about the ambient heat rise, detonation, and altering the ignition to avoid it.

Detonation is bad, and it IS very possible that the SC Box is detonating and you dont know it. Hopefully the ECU remap retards the timing when the knock sensors detect it. But even if it does, the fact it is trying to happen is a very bad thing, and does not bode well for the setup.

I wonder how (if any) of the IA SC systems have blown up the engine? Do they tell you? Do they warm you when you buy it?
__________________
Arctic Silver 2000 Boxster 3.4l w/Sport Design Package
Supersprint Boxster S Headers/Cats/Muffler
AASCO Lt. Wt FLywheel
Evo Intake
Partial Carbon Interior
Black Leather Sport seats
M030 Sway Bars
Litronics w/ Clear Corners
Boxster S brakes
B&M Short Shifter
PnP rear Speakers + Amp
pecivil is offline   Reply With Quote
Old 11-30-2006, 11:24 AM   #36
Registered User
 
Join Date: Apr 2006
Location: Chicago
Posts: 585
My vote is for the supercharger due to the heat issue with turbos. I also will second the use of an intercooler, larger injectors, appropriate fuel pump, intake, etc...
Sammy is offline   Reply With Quote
Old 11-30-2006, 11:37 AM   #37
Registered User
 
Join Date: Sep 2005
Location: Minneapolis/St. Paul, Minnesota, USA
Posts: 3,308
Quote:
Originally Posted by ohioboxster
Boggtown,
Jim and I have a difference in opinion and I dont believe we are out to hurt each others feelings. We have not made inflamatory comments to each other and I cant speak for Jim but Im not looking for a fight. If these comments were directed at us you are mistaken, if not disregard.
Hi,

OH, I'm not sure our opinions are that different. Detonation is a well-known phenomena and is caused under certain conditions whether it's in a Diesel, Aircraft or Boxster.

It's also true that the DME can respond so quickly to the knock sensors that you may be detonating and not know it. Or, detonating at some times and conditions and not others.

Again, I'm not saying that you are, but I also think that you cannot with 100% certainty say that you're not either. You'd need a data stream from the DME to see if the Knock Sensors are detecting anything.

No malice, it's all good fun and learning. It's about truth, either it is or it isn't. Problem in this case is that there's 'evidence' on both sides of the arguement. Glad you're being the Test Bed on this... Keep up the Good Work!

Happy Motoring!... Jim'99

Last edited by MNBoxster; 11-30-2006 at 11:44 AM.
MNBoxster is offline   Reply With Quote
Old 12-01-2006, 01:50 AM   #38
Registered User
 
Join Date: Feb 2005
Location: Seattle is now home!
Posts: 398
I drive mine every day I can with not one issue!

__________________
Everything is for sale

3.6, SC 'er and other parts for sale
JP-s-in st. louis is offline   Reply With Quote
Old 12-01-2006, 07:29 AM   #39
Registered User
 
Join Date: Apr 2006
Location: Seattle
Posts: 170
Quote:
Originally Posted by JP-s-in st. louis
I drive mine every day I can with not one issue!

Liar, you didn't want to take it out in the snow with me.

__________________
1996 993TT - current

2001 Boxster S (sold)
19" SSR GT3 - Cross coilovers - Custom Magnaflow exhaust - B&M Short Shifter - EVO intake - GT3 Seats - Hardtop

http://www.emeraldcitycustoms.com/images/box2.jpg

1986 Carrera (sold)
David_J is offline   Reply With Quote
Post Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -8. The time now is 07:11 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page