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

Post Reply
 
LinkBack Thread Tools Display Modes
Old 04-14-2019, 05:54 AM   #1
Registered User
 
truegearhead's Avatar
 
Join Date: Jul 2011
Location: Richmond, VA (The Fan)
Posts: 978
TimeTrial car, need additional 5-10hp

I need to find 5-10ho in my NASA TT5 car, it’s a 2.5L w/ headers, no cats, full exhaust, and a underdrive pulley. Is tuning an option? Poking around on the Internet it doesn’t look like this is a popular route. I’d rather not buy a 2.7l engine but might have to. Any ideas? If tuning is an option what do you all recommend?

Cheers,
Stu

__________________
1997 Boxster 4.2L Audi V8 Bi-Turbo
2003 911 C2
NASA HPDE Instructor
truegearhead is offline   Reply With Quote
Old 04-15-2019, 11:50 AM   #2
Registered User
 
Join Date: Jul 2009
Location: Arlington Heights, IL
Posts: 1,561
What is allowed by the rules? Drop weight. It's free. Dropping 85 pounds will be about 10 HP.
Flavor 987S is offline   Reply With Quote
Old 04-15-2019, 12:15 PM   #3
Registered User
 
The Radium King's Avatar
 
Join Date: Apr 2010
Location: Canada
Posts: 3,121
how about a early 996 plenum w cable throttle body)

or this ...

https://www.ebay.com/itm/OBX-Individual-Throttle-Body-Fits-Watercooled-Porsche-911-Boxster-ITB/182223111819?epid=1986020481&hash=item2a6d58068b:g:mEkAAOSwbsBXmlXx
The Radium King is offline   Reply With Quote
Old 04-15-2019, 01:41 PM   #4
Registered User
 
truegearhead's Avatar
 
Join Date: Jul 2011
Location: Richmond, VA (The Fan)
Posts: 978
Quote:
Originally Posted by Flavor 987S View Post
What is allowed by the rules? Drop weight. It's free. Dropping 85 pounds will be about 10 HP.
this is a really interesting one, or at least was for me. I've always thought cars with equal power to weight would have the same acceleration and as a bonus the lower weight car would have less weight to turn and brake. Fixed power to weight time trial has shown me this is very wrong. The problem is that aerodynamic, and rotational drag (and other drag) represent a bigger percentage power loss to the lighter, lower power car. I was at Summit point last week and happened to find myself right next to an S2000 which has the same power to weight but 30 more horsepower. I exited turn 10 at a higher speed only to have him walk right by on the straight. You exit turn 10 at 100mph and my car just doesn't have the power to pull out of the turn like his does at that speed.

Motorcycles are an extreme example of this. They have tremendous power to weight but above 100mph they are dogs compared to cars.
__________________
1997 Boxster 4.2L Audi V8 Bi-Turbo
2003 911 C2
NASA HPDE Instructor

Last edited by truegearhead; 04-15-2019 at 01:44 PM.
truegearhead is offline   Reply With Quote
Old 04-15-2019, 02:23 PM   #5
Who's askin'?
 
maytag's Avatar
 
Join Date: Mar 2018
Location: Utah
Posts: 2,446
Quote:
Originally Posted by truegearhead View Post
Motorcycles are an extreme example of this. They have tremendous power to weight but above 100mph they are dogs compared to cars.
You'll have to sell me on this, Haha. That's not consistent with my own experience.

Sent from my SM-G970U using Tapatalk
maytag is offline   Reply With Quote
Old 04-15-2019, 02:39 PM   #6
Racer Boy
 
Racer Boy's Avatar
 
Join Date: Sep 2015
Location: Seattle, WA
Posts: 946
Any bike over 600 cc is not a dog compared to cars! I had a 1000 cc bike that would go from 100 to 140 mph quicker than the Boxster can go from 0 to 40 mph.

But I understand, the power-to-weight thing doesn't really tell the whole story in the real world. The higher the speeds, the less the ratio holds up. I used to race a Datsun 1200 in class based on power-to-weight. That meant my 1600 lb, 72 HP car was up against an Alfa Milano, a turd that weighed over 1,000 lbs more but had over 100 more horsepower. I was much quicker in the turns, but he could rocket by on the straights, where I would then be stuck behind him in the turns the rest of the race.
Racer Boy is offline   Reply With Quote
Old 04-15-2019, 08:21 PM   #7
Certified Boxster Addict
 
Join Date: Nov 2010
Location: Los Angeles
Posts: 7,669
Quote:
Originally Posted by The Radium King View Post
how about a early 996 plenum w cable throttle body...
This is a good way to pick up 5-10hp.
__________________
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
thstone is offline   Reply With Quote
Old 04-15-2019, 11:06 PM   #8
Registered User
 
Join Date: Apr 2016
Location: SE Michigan
Posts: 497
Quote:
Originally Posted by The Radium King View Post

I do have a 996 TB on pretty much stock 2.5 with UDP and PSE, like quick throttle response and do not feel loss of low end torque that some typically suggest. Maybe because 2.5 intake pass is larger for most part with only the throttle butterfly that chokes down as the bottle-neck? My intake is all original from snorkel down to holmheltz chamber and it sounds very nice and audible at quick throttle opening.

Anyway I'm wondering if someone did dyno before/ after to ducument the change?

Also the link showing individual throttle body like carb stack, what is that like? Again any documented dyno results?
__________________
1997 Boxster arctic silver/ red, XNE riveted mahogany/ leather steering wheel & 917-style wood shift knob, Ben’s short shifter, PSE, 996 TB, UDP, stereo/ center console delete, hardtop and speedster humps, daily driver rain or shine or snow!
Boxstard is offline   Reply With Quote
Old 04-16-2019, 07:12 AM   #9
Registered User
 
Join Date: Jul 2005
Location: MA
Posts: 880
987 airboxes show improvements on S motors. I don't recall feedback from anyone who has tried it with a 2.5.
__________________
98 Arena Red 986
Stroked & Blown is offline   Reply With Quote
Old 04-16-2019, 07:51 AM   #10
Registered User
 
Lemming's Avatar
 
Join Date: Apr 2016
Location: B'ham, AL
Posts: 265
Back when I did TTB and GTS3 with NASA (924S with 3L) I was the lowest HP, but lightest car. Great in many respects but got killed on long straights (where it is easy to pass), by higher HP cars with the same power to weight.

996 TB is a good idea, but finding a good used mechanical unit is not easy and new ones are over $1,000. Have you considered having your TB bored? Not sure if you will get the 10 HP that you need, but you will get some extra HP for those long straights at VIR.

You straight that you have full exhaust, do you mean stock?

You can tune the car and expect to get a few more HP as well. I would stay away from a preset tune and get one done with the car on a dyno for best results.
__________________
Tim
1998 986 (daily driver Frankencar)
1999 986 (SPB)
2001 986 S (parting)
2015 981 (sold)
Lemming is offline   Reply With Quote
Old 04-18-2019, 10:48 AM   #11
Registered User
 
Join Date: Mar 2018
Location: Spokane wa
Posts: 16
If I were looking for a few more hp here is what I would try. Take this with a grain of salt as I have not done any of these or have proof that they would make more power on a m96 2.5 engine.

Intake: 987 air box and larger smoother intake tube as a minimum or (again a little different but could be easily tested) make a straight and short intake that passes into the trunk to a larger cone filter. Vent the trunk for ample fresh air.
Get a 996 cable throttle body or have the stock one bored out, I believe a 987 intake “t” will fit or do what ben006 did and 3D print one that has a larger and smoother radius.

Engine: Could you live with out power steering? Spinning that pump at 5k would be worth a couple of hp.
Do some at home port and polish on the heads if your comfortable with that much work. (David Vizard has a good book on the subject)

Exhaust: looks like you have most everything covered. The only gripe I have is with the header selection for the 2.5 engines. It seems to me that most headers are oversized for the smaller engine and a custom header with smaller but longer primaries could be worth some midrange to upper end horsepower.

Tune: all of these would benefit more with a custom tune but that seems to be difficult with the 2.5 engine and finding someone to do it.

Again opinions will differ and I’m not saying that all of these will make more power just ideas I had on how to do it. Thank you have a good day
Sammyj is offline   Reply With Quote
Old 04-19-2019, 05:30 AM   #12
Registered User
 
jsceash's Avatar
 
Join Date: Aug 2009
Posts: 1,466
Garage
Quote:
Originally Posted by truegearhead View Post
this is a really interesting one, or at least was for me. I've always thought cars with equal power to weight would have the same acceleration and as a bonus the lower weight car would have less weight to turn and brake. Fixed power to weight time trial has shown me this is very wrong. The problem is that aerodynamic, and rotational drag (and other drag) represent a bigger percentage power loss to the lighter, lower power car. I was at Summit point last week and happened to find myself right next to an S2000 which has the same power to weight but 30 more horsepower. I exited turn 10 at a higher speed only to have him walk right by on the straight. You exit turn 10 at 100mph and my car just doesn't have the power to pull out of the turn like his does at that speed.

Motorcycles are an extreme example of this. They have tremendous power to weight but above 100mph they are dogs compared to cars.
The S2000 has a couple things you don't. It cranks to about 8200 RPM, and a 6 speed transmission. I agree that your best option is reduce weight. The rule would ban you from the type of mods that are being suggested here or at the very least cause you to be flipped into a higher class. The Power steering mod with electric PS pump is a good power saver. Then If you haven't done it yet remove the AC compressor, plumbing, and coils at the radiators. A second thing the AC delete does, it allows you to turn on the AC which automatically cycles on the radiator coolers but with the compressor out there is no power loss.
__________________
2003 Black 986. modified for Advanced level HPDE and open track days.
* 3.6L LN block, 06 heads, Carrillo H rods, IDP with 987 intake, Oil mods, LN IMS. * Spec II Clutch, 3.2L S Spec P-P FW. * D2 shocks, GT3 arms & and links, Spacers front and rear * Weight reduced, No carpet, AC deleted, Remote PS pump, PS pump deleted. Recaro Pole position seats, Brey crouse ext. 5 point harness, NHP sport exhaust

Last edited by jsceash; 04-19-2019 at 05:32 AM.
jsceash is offline   Reply With Quote
Old 04-20-2019, 03:32 AM   #13
Registered User
 
truegearhead's Avatar
 
Join Date: Jul 2011
Location: Richmond, VA (The Fan)
Posts: 978
Quote:
Originally Posted by jsceash View Post
The S2000 has a couple things you don't. It cranks to about 8200 RPM, and a 6 speed transmission. I agree that your best option is reduce weight. The rule would ban you from the type of mods that are being suggested here or at the very least cause you to be flipped into a higher class. The Power steering mod with electric PS pump is a good power saver. Then If you haven't done it yet remove the AC compressor, plumbing, and coils at the radiators. A second thing the AC delete does, it allows you to turn on the AC which automatically cycles on the radiator coolers but with the compressor out there is no power loss.
Thanks for all the suggestions guys, I didn’t think of the powering steering pump. As far as the tune, who can do this? I can’t find any information anywhere on it bring available.
__________________
1997 Boxster 4.2L Audi V8 Bi-Turbo
2003 911 C2
NASA HPDE Instructor
truegearhead is offline   Reply With Quote
Old 04-22-2019, 08:04 AM   #14
Registered User
 
truegearhead's Avatar
 
Join Date: Jul 2011
Location: Richmond, VA (The Fan)
Posts: 978
I’m looking into the throttle body suggestion and the Pedro Power pack seems like a good deal. I’m sure it doesn’t bet 30hp as advertised but it’s not crazy expensive. Is anyone running it? I wish he had a dyno to prove the results. Kind of suspect that he doesn’t.
__________________
1997 Boxster 4.2L Audi V8 Bi-Turbo
2003 911 C2
NASA HPDE Instructor
truegearhead is offline   Reply With Quote
Old 04-28-2019, 10:59 AM   #15
Registered User
 
truegearhead's Avatar
 
Join Date: Jul 2011
Location: Richmond, VA (The Fan)
Posts: 978
I like the idea of moving the intake to the trunk and punching a hole through the engine bay. The MAF would have to be right at the throttle body. I wonder if that would require a custom tune.
__________________
1997 Boxster 4.2L Audi V8 Bi-Turbo
2003 911 C2
NASA HPDE Instructor

Last edited by truegearhead; 04-28-2019 at 11:12 AM.
truegearhead is offline   Reply With Quote
Old 04-28-2019, 10:05 PM   #16
Track rat
 
Topless's Avatar
 
Join Date: Nov 2006
Location: Southern ID
Posts: 3,701
Garage
Drop the weight, it's a physics thing. It will improve acceleration, braking and cornering (faster timed laps). 5-10hp will help acceleration only and you will still get walked by the S2000s on the straights because they have 40hp more, and shorter gears so they put the power down more effectively on long straights. Weight is free and won't require you to punch a hole in your firewall. Drop the weight and get them in the corners.

Another tactic is to run smaller diameter tires to effectively lower your final ratio and shorten your gears.
__________________
2009 Cayman 2.9L PDK (with a few tweaks)
PCA-GPX Chief Driving Instructor-Ret.
Topless is offline   Reply With Quote
Old 04-29-2019, 02:32 AM   #17
Registered User
 
truegearhead's Avatar
 
Join Date: Jul 2011
Location: Richmond, VA (The Fan)
Posts: 978
Quote:
Originally Posted by Topless View Post
Drop the weight, it's a physics thing. It will improve acceleration, braking and cornering (faster timed laps). 5-10hp will help acceleration only and you will still get walked by the S2000s on the straights because they have 40hp more, and shorter gears so they put the power down more effectively on long straights. Weight is free and won't require you to punch a hole in your firewall. Drop the weight and get them in the corners.

Another tactic is to run smaller diameter tires to effectively lower your final ratio and shorten your gears.
Ya I hear you. It’s 2300lbs dry with a cage and I’ve added ballast to get to the power to weight limit. Even if I was allowed to loose weight there really isn’t any left to remove. The only thing I really haven’t done is replace the doors with fiberglass.
__________________
1997 Boxster 4.2L Audi V8 Bi-Turbo
2003 911 C2
NASA HPDE Instructor
truegearhead is offline   Reply With Quote
Old 05-07-2019, 06:57 AM   #18
Registered User
 
BYprodriver's Avatar
 
Join Date: Oct 2008
Location: O.C. CA
Posts: 3,709
Garage
Have exhaust pipes Ceramic coated to retain heat inside.
__________________
OE engine rebuilt,3.6 litre LN Engineering billet sleeves,triple row IMSB,LN rods. Deep sump oil pan with DT40 oil.
BYprodriver is offline   Reply With Quote
Old 05-11-2019, 07:28 PM   #19
Registered User
 
jaykay's Avatar
 
Join Date: Sep 2009
Location: toronto
Posts: 2,668
Quote:
Originally Posted by Topless View Post
Drop the weight, it's a physics thing. It will improve acceleration, braking and cornering (faster timed laps). 5-10hp will help acceleration only and you will still get walked by the S2000s on the straights because they have 40hp more, and shorter gears so they put the power down more effectively on long straights. Weight is free and won't require you to punch a hole in your firewall. Drop the weight and get them in the corners.

Another tactic is to run smaller diameter tires to effectively lower your final ratio and shorten your gears.
......was going to suggest going for some very light weight track wheels. I think this is very often overlooked. Spinning up heavy wheels robs power.

__________________
986 00S
jaykay 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 10:54 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