Performance upgrades for carreras?

[ChemMan]

I have been looking through old posts on this topic and had some questions.

I have a hollowed out cat and will likely look for a pre-muffler or real cat bypass tube at next years swap meet. Also have a bursch muffler and SW chip. Since I drive the 911 until the snow and salt hits the ground, I do not want to lose the heat. So besides going up to 3.5L, what options are there for performance upgrades to a 3.2L?

Thanks

[Wavey]

Since you already have the chip and muffler, going to a pre-muffler will get you a few horses. MK's unit recommended. Beyond that, since you don't want to go to SSIs or bigger P&Cs,per Steve Weiner:

"Regrind your cams to the 964 profile. Your cams can be reprofiled by a few companies; We use Webcam. If you retain the Motronic system, stick with 964 cams.

Extrude-hone your intake manifolds. Leave your heads alone as they have plenty of airflow up to 340 HP. (930 heads are nowhere near as good as your Carrera ones)"

[911st]

You have a nice motor set up as is and anything past this is going to cost a bunch for a little.

A gutted cat might even be better than a cat bypass or pre muffler. No one really knows as there have not been any good back to back tests that I could document.

There is a Turbo kit offered by Protomotove for about $5-6k that gets you to about 330hp.

A stock 3.2 with stock cams if made to breath right can make 270fwhp. The best example of this is going to carb's and larger tube equal length headers with a sport of race muffler. However, this requires spinning the motor up around 7k at which point the rod bolts become an issue.

Adding cams might get you up to 10hp unless the motor is bigger and the restrictions at the exhaust and intake are addressed. To do this right you will need to have your rocker arms re-ground and buy sport valve springs and or readjust spring height/tension.

Go to 911chips.com and look at their dyno section. It is a great resource as to what works and how much.

Getting the restrictive Air Flow Meter out of the way and going to race headers - exhaust and/ or making the motor bigger are the main goals to making more HP.

Another approach for increased performance is to look at making the car lighter.

Also, close ratio gears have the potental to transform a car. Gears can significantly increase your average HP per gear . For example, on a chiped and cat bypassed car, when we shift in to second we come in at around 4600rpm where we are at about 160rwhp (apx 188fwhp). Redo the gears so we come in at 5200rpm and we are at 190rwhp (apx 230 fwhp).

There is more speed in cornering and braking than acceleration.

[Rick K]

To the point made earlier - you're at a point (w/ bypass & chip + sport exhaust) that you will be spending lots of $ for a few horses here or there. Although an M&K will give you a much more aggressive sound than the Bursch.

Not sure where your car is at - but IMO spending dollars on brakes (SS lines, fresh calipers, fresh rotors, better pads) & suspension (tbars, bushings, sways) is a better bet for performance.

[Wavey]

Originally Posted by 911st

A gutted cat might even be better than a cat bypass or pre muffler. No one really knows as there have not been any good back to back tests that I could document.

Bruce Anderson tested a straight pipe and a factory premuffler and said the premuffler is good for 7 HP, I think - I can look it up if you'd like.

[911st]

Originally Posted by Wavey

Bruce Anderson tested a straight pipe and a factory premuffler and said the premuffler is good for 7 HP, I think - I can look it up if you'd like.

I believe he replace the cat w a factory euro premuffler and made 7hp.

Until I see a back to back I suspect a premuffler and a cat bypass are equals. It might even be possible a well designed bypass might out flow a pre muffler but we do not know for sure.

Matching the chip to any exhaust change is the only true way to know if there is any real efficiencies being created. At some point in an effort of reducing back pressure ideal AFR's will be passed and the could start to go to lean after 5000rpm where the 3.2 Motronics no longer sense changed in air flow very well. So it might be possible to put the best exhaust system on and find a decrease in HP until the AFR's are corrected.

At least that is my thinking.

[mxessin2]

75 - 100 Hp from a simple Nitrous works pretty good on a 3.2

[ChemMan]

Originally Posted by Wavey

Beyond that, since you don't want to go to SSIs or bigger P&Cs

Wavey,
Forgive my ignorance on this subject, but what exactly are P&C's?

[jurhip]

Getting the restrictive Air Flow Meter out of the way and going to race headers - exhaust and/ or making the motor bigger are the main goals to making more HP.

I don't know why people think its restrictive. It opens to allow the required flow of air into the engine. Has anyone actually checked the pressure drop through all flow and load ranges. This would tell you if it is really a restriction.


Cars went to MAF sensors to adjust for air density, not to reduce restrictions. This allows for optimal FI through differing temp and pressure ranges.

[911st]

Best HP Bruce Anderson notes with SSI, muffler, & chip = 226hp.

With MAF replacing AFM = 236.

Adding race headers and race exhaust = 240

Carbs replacing EFI = 265

Breathing improvements made 10hp w change to MAF then another 25hp w change to carbs or 35hp of the 39hp gain above.

It probably depends on the motor and where the restrictions are. If the exaust has been optimized, then the intake side becomes an issue.

There is a guy in Sweeden on the board here that has a stock euro 3.2 with ITB's and makes 270hp w equal length headers and a stock 2/1 muffler. This compairs with the BA 265HP carb motor on a lower compression USA car.

[jurhip]

I am still not convinced the increased flow from the MAF caused the 10 hp increase.
One needs to take into account fuel map tuning when utilizing the MAF as well as the increased accuracy of this type of sensor over the "volumetric" stock type sensor.

But, I am NOT saying a MAF doesn't result in increaed HP. I am just questioning why it makes it. I haven't seen any hard test data that it is due to reducing inlet restrictions.
If you are looking for HP, then this is a viable upgrade.

[Bullet Bob]

I recently had my 3.2 completely rebuilt (top and bottom) and the only changes from stock were SSI headers, GHL muffler (2 in 1 out), and Wong chip. The engine produced 239Hp on an engine dyno. This was with the stock Alusil Ps & Cs, although they were new. I got a great deal for the set on Ebay.

Ps & Cs are pistons and cylinders

[scarceller]

I also doubt that a MAF alone will result in 10HP. The reason this main seem to be true is that with a new MAF comes a new chip and the new tuned chip is most likely responsible for most of HP gain and not the MAF.

But how much HP could you have gotten from just a properly tuned chip and the stock AirFlowMeter? I know first hand you can find 10HP easily in a stock Carrera with a tuned chip and nothing else changed. Even the factory found 10+ HP from 84 to 89 cars simply with chip tunning, the 84 and 89 engines are the same so how can it be that the 89 has 10+ more HP? Simple the 89 has a different more aggressive chip with more ignition timing. You can upgrade any 84-86 car by simply moving to the 89 DME and chip!

In the end be very careful of claims that say a MAF got me 10HP they simply may not true because along with the MAF came the most important gain which is the new chip with more aggressive timings.

I have not researched MAFs much by my bet is they really won't get you much extra HP over a Steve Wong chip. Possibly they will get you better throttle response but you can also achieve better throttle response with the Stock AFM and some chip tuning tricks.

Steve sells chips and he also sells (or did sell) a MAF upgrade with a tuned chip. Maybe Steve will chime in here and let us know how much more you can expect from a MAF upgrade vs a simple chip upgrade?

Hope this helps

[jurhip]

Scarcellar, one cannot tune off a volumetric flow device (as in 84-89 carreras) as well as an MAF, as this measures air density. You will always be able to optimizes engine tuning better with the MAF.

Max HP reading, though may or may not be affected. Driveability and HP outside peak power engine speed will be affected.

[rfloz]

One of the very best performance upgrades you can do is strip out as much of the "foo-foo" stuff as you can, A/C, heater, back seats, stereo, etc., etc.

I've taken about 200# out of my 3.2 and it really livens it up. Cost is minimal, too.

[scarceller]

Originally Posted by jurhip

Scarcellar, one cannot tune off a volumetric flow device (as in 84-89 carreras) as well as an MAF, as this measures air density. You will always be able to optimizes engine tuning better with the MAF.

Max HP reading, though may or may not be affected. Driveability and HP outside peak power engine speed will be affected.

Agree, MAF is better measuring device. The AFM calculates Air Mass from Air Volume + Intake Air Temp it's not perfect but you'd be surprised it's very close. The question is how much better is the MAF than the AFM? I think the MAF may get you better throttle response but not sure about extra Torque or HP. Most MAF kits are in the $1500.00 range or more, your better off spending this money on Exhaust and Chip changes. My car is a 3.2L with these mods:
-Euro PCs
-WebCams 20/21 grind
-SSIs with 2in2out M&K pipe
-Extrude Honed and flowed intake
-Cone Air Filter
-Custom Chip (aggressive timing maps and tunes AFRs)
Last dyno run it cranked 230HP at the wheels (about 265 crank HP).
It took a lot of cash to get about 20-25 extra HP out of this 3.2L.
The car is also very light with AC delete among other things. It will turn 0-60 in 5seconds or better without pushing it very hard off the line (These cars have weak 1st gear).

I'd do these changes in this order:
1 - weight reduction makes a big difference if you can drop 200lbs.
2 - Then the exhaust would be next
3 - Chip (don't buy any old chip get a good one, some will do damage)
4 - Extrude Honed and Flowed intake
5 - Cams
6 - MAF (somewhere near last because of cost and what you'll gain)
7 - Air filter (take it or leave it, not much to be had here)

Just my opinion

[911st]

I am not pushing the MAF. I see no advantage to just adapting from AFM to MAF unless the AFR's and timming are set to be ideal and to accomidate any increase in air flow. It migh be that part of the increase past makers of MAF kits make is from the tunning effect and not the increased air flow they might alow.

Having said that, looking at the cross section of the stock AFM it just dose not look like it would flow a bunch. Per SW's wrigt up on his past MAF conversion. He notes the cross section of the stock AFM is 27 sq. cm. The MAF had a cross section of 55 sq. cm. He also notes a 15 to 20hp gain. Dose anyone know about what the cross section of the throtle body is?
http://www.911chips.com/HFM1.htm

It migh be that the gain from such a mod might be more noticable up top and not available w/o a proper exaust.

However, it seems apparant from mods that keep the stock long block and change the intake to ITB's or carbs that there are substantual gains to be had on the intake side of a 3.2. HP as 260-270hp have been had this way. Using Bruce Anderson's numbers once the exaust side is fixed it looks like intake side improvements can make a very substantal impact of about with him documenting 25hp from just changing to carbs on a motor that already had a race exaust system.

It might be that if we could clean up the manifold via extrude hone as noted, convert to a MAP system, open up the TB, and eliminate that 90 deg elbow before the TB and we might approach the power a carb or ITB can make.

By the way, if someone has not checked out the dyno plots at 911chips.com it is worth the effort.

I love the following chart that SW put togeather. It showed that cams, carbs, MAF conversions and such are not neccessarly needed to make over 250 hp and up to 270hp is possable on a stock cam and block. (My chiped and bypassed makes 217rwhp or 255fwhp -- different sized horses I suspect).

Originally Posted by Steve W

I've compiled a spreadsheet of expected power output values based on a internally stock 3.2 Carrera motor based on dyno tuning data that I've accumulated from many cars over the years. The output values are given in engine flywheel hp assuming a Superflow engine dyno such as at Jerry Woods. You results may vary, based on the flow quality of your muffler, but for a healthy 3.2 motor, I estimate these values to be accurate to within 2-3 hp of each other.