I was wondering, I got some small mods installed and just wondering if I should do a tune? Is tune with these parts is even necessary?

-AWE Mufflers
-NHP CatByPass Pipes
-BMC Air Filter
-AirBox Hose and Plug

 

Yes, definitely.

Go SOFTRONIC

 

Same question - mods include plugs, K&N drop in filter, GT3 Plenum and Throttle Body. No muffler mods, non turbo normally aspirated engine... To tune or not to tune??? Car runs good, but fuel mileage dropped considerably per the trip computer, not that I'm counting.

 

How many legitimate tuning options are there ?
Please help me understand your preference for Softronic over Evoms ?

 

...or REVO?


As mentioned before, with minor mods what you will get with am tune is modified throttle mapping ala Sport mode but less severe. While it may be more fun to drive (love the revo map) it is not to be confused with more hp.

 

Don't expect any big increases in power from a tune. Most of these so called tunes, are changing the throttle response to a more aggressive response, like stated above.
All these tunes are doing is altering the timming so very slightly, and altering the fuel slightly . The big picture is, the timming is controlled by the knock sensors, so they knock sensor is controlling the over all power output period.
Buy a ipd , and a 82mm throttle body, that will be better money spent for sure.
Good luck.

 

The biggest gains that you will usual see from these types of cars, in my experience (NA Audi v8/v10, Porsche 997s) comes from the swap to high flow cats, (or straight pipe), along with a tune and high octane gas. The stock ECU will compensate up to a certain point, but to get the most out of the better air flow, you want a tune.

As for the other mods such as BMC air filter, GT3 TB, IPD plenum, etc, I have not been able to find any absolute proof that they will gain you any HP over stock. Combined with the cat delete and a tune, they may help. But on their own I question their value.

This is just my opinion, based on my experience and research. For the cost of the Softronic tune, I think it is well worth it. That being said, I havent installed my headers and high flow cats yet. Just running 94 octane and the tune. I expect to see additional gains once I have my other parts on the car. Still on the fence about the GT3 TB, as I have heard as many people experience problems with them as people who like them. My feeling is, after cats and tune, I would rather save my money for a VF supercharger. I only got the headers because they were part of a package I was buying.

 

This is some data from an online Throttle Body calculator

http://www.hipermath.com/math_center...g_calculations

Calculate Throttle Body Size Based on Bore, Stroke and Number of Cylinders
Bore:
3.9
inches
Stroke:
3.26
inches
Number of Cylinders:
6
Best Power Rpm:
7000
This is the rpm at which you want your engine to produce the most horsepower.
Calculate
Throttle_body_1

= 68.9505



68.9505 millimeters (2.7146 inches) is the best size for a street going car. It will provide the best power throughout the rpm range.

68.9505 * 1.15 = 79.293075 millimeters (3.12179 inches) is better for racing. 79.293075 is 15% bigger than the street going version and will provide more horsepower at higher rpm ranges. The drawback is it may cause poor idle and/or make it necessary to increase the idle rpm to make the engine idle smoothly. That, along with less power at lower rpms, is the reason most people do not drive cars with racing engines on the street.

The bore and stroke are from the 997s 3.8l engine.

Stock TB is already 74mm. So, if you are not racing, you already have a TB that is well sized (and on the large side), according to the calculator. If racing, and other mods (like high flow cats), then you may get a small HP gain at the very top of the RPM range going to an 82mm GT3. But you arent going to see that until you hit the bottleneck of efficiency of the stock 76mm. So likely just above 6800rpm. Below, you may lose power, as many have reported.

Tune way before bigger TB, for me.

 

Thanks @halo777 that was very helpful on the TB. I like to have science and data behind my mod purchase decision.

Although I also realize the tune doesn't yield much peak HP but I think I will enjoy a throttle response that is more responsive than stock but less sensitive than sport mode....

 

Here you go. 3.6L 997 06, has factory pse exhaust. In blue, ecu tunned, only. In red , same tune, with 82mm gt3 throttle body and ipd. The heads flow more than enough air, the engine was choked down from the factory, to not get close to the S model in power.

 

How was the base 997 3.6 models choked down from the factory with the stock TB, compared to the S models? Dont they both use the same 74mm TB stock? Wouldnt that mean that the larger displacement 3.8L S-models were actually the ones choked down?

 

The 3.8 S has smaller cams, and 2mm bigger pistons than 3.6 so the 3.8 is almost the same engine as a 3.6. The smaller 3.4 responded really well too with the larger throttle body also.
When a engine is choked off on power, they will respond by more air in, thus raising there VE.

 

That still doesnt answer my question... how can you claim that the 3.6 engine was choked off by the size of the TB, when the 3.6 and the 3.8 both have the same 74mm TB?

Also, I don't put much faith in dynos. They can be too easily manipulated. For me, things have to make sense. And the dyno you provided doesnt, combined with your statements.

You state that the only difference between the red and blue run, as the TB was changed from 74mm to 82mm GT3, and IPD plenum was installed. My problem with the dyno is this, if the TB was truly a bottleneck, then you would have seen a decrease at the top end of the dyno, where the air was engine was getting choked, as you put it. However, if you look at the dyno, you see a pretty consistent gain all the way from 4000 RPM. Are you telling me that the 74mm TB was a bottle neck at 175whp? To me, that doesnt make any sense.

In any case, I guess we will just have to agree to disagree.

 

OK, I see why you (or whoever did the dyno) got those results. It has to do with the air/fuel ratio. The red line run is consistently flat-lined at about 12.9, which is pretty close to ideal for max performance from an NA engine.

The blue line is flatlined at 12.0 from 4000rpm on, which is too rich for max performance on an NA engine.

What tune was on the car?

 

Highly debatable subject. As for me instead of a ECU tune, i concentrate more on shedding weight. Fix to shed 40 lbs of unsprung weight off 4 corners by going with lighter wheels.

However i must admit my mildly modded FD3 RX7 perform much faster at a safer AFR margin after a road tune by Steve Kan.