IPD Competition Plenum + GT3 Throttle Body Installation

I am posting this for those of you who are contemplating this upgrade but having doubts about performance gains. I was one of doubters before this installation who spent a lot of time reading reviews and talking to people who have in depth knowledge on mechanic of fluids and generally who have experience with racing and tuning. To sum it in one sentence: "This is one of the best upgrades you can do for your naturally aspirated flat six engine provided that you already have a less restrictive exhaust system than stock". I have the following upgrades on my 2002 C4 Cab: The upgrades were done in the following order: FVD Brombacher Sport exhaust Sound Version FVD 200 Cell sport catalytic converter. FVD Race tune BMC Flat filter IPD Competition Plenum with GT3 Throttle body (82mm) and straight hose. The car now has loads of low and mid range torque and pulls strongly to the red line (7500 RPM with this tune). The sound is as close as it gets to GT3 sound. It sounds like a race car. I have recently driven a stock 996 V2 and compared it with my car. Throttle response is improved by 20 to 30% compared to the stock car. The car is way faster than the stock. It is not comparable. Additionally, I have compared both cars to BMW M240i (my daily driver) which has a 3.0l turbo charged engine capable of making 369 lbf at 1500 RPM. This car does 0-60 in 4.5 seconds. The stock car is significantly slower than the Bimmer. My upgraded C4, although it doesn't have this amount of torque, does not lag behind the Bimmer. Torque distribution is more linear and in my humble opinion natural all the way to 6K. Torque is there all the time at any RPM and any gear. Before doing this upgrade I was a little skeptical about the gains having read various posts and comments from people who installed it. However after some analysis I have come to conclusion that most people who didn't experience any gains were the ones who have the stock exhaust and no software tune. So in order to enable the engine to breathe faster you need to open it up at the exhaust. Also, new mapping is required to take advantage of larger amount of air coming into the engine. That's my two cents. I will post the video with the sound of the car when I get a chance to make it. Let me know your experiences.

I�m real curious to know how you measured the improvement in throttle response.

I appreciate this feedback. I'd be looking for improved throttle response over any power increases. I figured not much would be had. What other tunes are available that would take advantage of this setup? Would Fabspeed work just as well?

could the throttle response be a result of the tune mapping? Thats all it seemed to do for me.

You will get both the torque and high end HP. Throttle response is amazing. Yes, Fabspeed will work too. All top brands products are similar in terms of sound and quality. But, you have to do the exhaust first and the tune to capitalize on performance gains. Otherwise, you probably won't see much difference, like all those people who complained about IPD plenum gains.

Yes and no. I had the mapping done before the IPD and TB installation, along with the muffler and 200 Cell cats. That was a good improvement over the stock throttle response. However, it was only after IPD and TB installation, when I couldn't recognize my car anymore. Guys, we are not talking 5-10 HP and 10 lbf of torque. That is difficult to notice. We are talking about 50 HP and 20-30 lbf of torque of improvement. The throttle response is instantaneous at any RPM. Of course, I didn't do Dyno to back it up, but I don't need to do it because it is so obvious that even a layman would see the difference between the stock 996 and my car.

Start the stopwatch and floor the gas pedal in the first gear at the same time. Stop the stopwatch when you reach 60 mph speed. Record the time. Do this 3 times. Do the same from the rolling start and the second gear. Do the same in the third gear. The goal is to measure the time required to get from one speed to another. For instance; from 20 mph to 110 mph. Compare the results with the stock car.

Too bad after spending all this money you didn't bother to do before and after dynos to see what exactly were the performance changes.

I agree. However, all these updates were done in stages. One after another. When I first started doing it, I remember my mechanic telling me to lay off a bit from spending too much money. Enjoy your car a bit instead of rushing from one upgrade to another, he said to me. I can still Dyno it. I am just worried about it. Don't want to do any damage to the car. I don't have any experience with it. Any thoughts?

Not a fan of butt-dyno threads. Subjective analysis has never been a reliable way to measure anything. On engines with larger displacements like our csrs, increases in HP and TQ have to be more significant to actually feel. Without a before and after dyno, it's just speculation. It would be nice to see a dyno of your car the way it is now though.

That is exactly what I am trying to tell you. This is a very significant difference from the stock car. I don't know the actual figures but it is day and night in terms of acceleration. It is up to everyone to decide whether they will trust my judgement or not. However, there are lots of people on these forums who have installed this product and are very happy with the gains. I am one of them. I understand that there are some who are not impressed with it too. But from what I have read, most people who didn't feel any gains did not install the throttle body and less restrictive exhaust system.

Increased noise can easily be confused with more power and better throttle response. No saying your modifications didn't increase the power of your engine but maybe those number are skewed by how things now sound. Also, did the power just shift in the power band or was there an increase under all rpms? It's difficult to gauge this when the car sounds like a race car. A race tune usually concentrates on near redline performance because that's where those engines spend most of there time and that's where they need the most power. How does this translate to daily driving? Race cars are terrible daily drivers.

Record your max-MAF value display and post to this thread. https://rennlist.com/forums/996-foru...potential.html

I agree with your statement about higher noise levels making is feel like the car is moving faster. There is a little bit of that too. The increase in torque all across the range, at all rpms and at any gear. Yes it is difficult to gauge the car when it sounds like race car. However, this sound can be easily modulated with the throttle. If you want it to sound like race car, you just step on the gas pedal. If you want it to sound tame, you just accelerate at a normal pace and car doesn't sound like a race engine. That is the beauty of this exhaust system. It is the sound on demand. I hardly ever rev the car beyond 6K since I am not racing or driving it on the track. However, I have noticed a brutal acceleration past 5 K in 2, 3 and 4 gears. What makes it more impressive is that you don't have to rev it high to be fast in daily driving. You can stay below 4K and still be faster than most cars on the road. Do your overtaking and lane changing between 3 and 4K. The torque is available as low as 2K. With the stock engine, you need to past 3K to feel any torque. For the stock engine you need to do daily driving between 3 and 5 k to be able to pass comfortably. This one is between 2 and 4k.

Is this any accurate? Where do I buy this and how does it connect to the car?

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I would say it's pretty accurate since it measures the direct Mass Air used to make the power. Dyno's accuracy has also been questioned as they read different on different days, different Dyno's, even on different runs back to back are usually averaged. If you read through the thread there are many ways to record this, but for starters and good $50 dollar bluetooth OBD2 dongle and a Torque Pro app will get you close.

Thank you so much. Are you using the Torque Pro App? I found this Bluetooth on Amazon. Amazon Amazon Is this one ok?

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Yes, I use the Torque Pro app, and also have Durametric to use also. The Torque Pro app is my favorite bluetooth app, easy to use has many customizing features and add-ons. I have no experience with the Veepeak dongle, the OBD2 dongle can range anywhere from $10 to $400, but my experience is the refresh rate and staying connected/ no lock-ups on anything under $50 suffers. Try this one Amazon Amazon

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If you're using an iPhone, you'll need a WiFi ODBII reader.

I am using Android.

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Sticking definite numbers to something you have no basis for is quite meaningless. With another throttle-body, first and foremost you're changing the feel of your throttle pedal. Most of these upgrades cause a larger absolute TB opening with less pedal travel. It tricks the mind into thinking that power output increased, since now it "goes faster with less movement of the go-fast pedal". Words like "snappy" and "better response" are often heard. It's easy to mis-interpret such change as performance-enhancement, simply because it's a noticeable change in how your car behaves. In reality, a TB upgrade doesn't make the engine take in a significant amounts of extra air, let alone a gigantic >15% of it. Your car feels snappier, it feels more responsive, because you have to push the throttle less for the same result. But you simply can't put HP and Torque numbers to those subjective feelings.

I run some tests soon to add the actual performance figures to the subjective feeling.

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In... for some real numbers!!!

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So true. I wish I could find the testing done on a dyno with all these mods mentioned. The end result was no real HP gains but a ton of money spent on parts...

Too many doubting Thomases on these forums. I am all for scientific proofs. I do that every day. That is my daily job. However, sometimes you have to stick to your gut feeling and do things that may not look logical and scientifically backed up. Trust me, it was worth taking this risk. You can continue doubting all of these performance gains. In the meantime, I will be having fun in my car.

wOTE=mirko_tripic;15813871]Too many doubting Thomases on these forums. I am all for scientific proofs. I do that every day. That is my daily job. However, sometimes you have to stick to your gut feeling and do things that may not look logical and scientifically backed up. Trust me, it was worth taking this risk. You can continue doubting all of these performance gains. In the meantime, I will be having fun in my car.[/QUOTE] I understand but when you throw out hard numbers from your butt dyno there's always going to be some doubt...Drop your results in the "Mass Air Flow" thread and it will be useful to others. The main thing is your happy with what you've done and I'm not trying to knock you down but I've done a little research on the topic.

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A quick Google Search returned this: https://www.renntech.org/topic/16369...t-to-the-dyno/ 99 C2 w/ 42K miles Intake, exhaust and headers 256 RWHP 222 LB-FT Everything I read leads me to believe that the most "popular" mods done to a 3.4-3.6L result in a poor cost-benefit.

I will, as soon as I receive the Bluetooth OBDII reader.

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Excellent, we look forward to seeing your stats. May I ask what the cost was for all your upgrades?

" In summary my HP over the stock numbers was around 13.5 to 21 HP peak gain, and 19 to 25 ftlbs peak torque gain. I'm curious what the numbers would be with a 20 degree temp drop. I may go back in early winter and retry." So 20 HP and 20 lbf of torque gains is what he measured. You don't think that these gains are substantial for what he's done to the engine? Firstly, I think that his gains are substantial for his mods. Secondly, what I have done to my car is totally different from his mods. I have much more comprehensive list of mods. Exhaust, Tune, 200 Cell Cats, BMC filter, Competition IPD Plenum, GT3 Throttle body (82 mm) and straight intake hose. He does not have the software remapped. This is very important, in order to take advantage of these mods. Now the question is : Are these mods worth the money spent on them? Probably not. You can get better results with the supercharger. However, you will still have to spend thousands on the exhaust to improve the sound.

You don't want to know. The number will not make any sense. I will sum it up and let you know.

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I think (for me) just saving the money and doing a 4.0 build is in my future.

Here you go.

Is that in US or Canadian dollars?

Wowzers! US $1.00 to Canadas $1.35

Yes.

Whoa over $1,000 just for install. Ridiculous

I meant to say. It is in Canadian dollars.

Well. This was done in four stages and there were snapped bolts and replaced muffler brackets. Just a bracket alone is $150 of the ebay, for a used bracket. $400 for a brand new if you buy online. There were other parts that were broken, such as oil filler. Once you start working on these cars you never know what awaits. If you can do this yourself, you can probably same some considerable amount of money.

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Generally true, however you said you felt the biggest 'gains' after installing the plenum+TB, but you also said you didn't remap after fitting those. I've read the other guy's topic and he didn't really measure any comparison at all. He never did a before- and after. He measured the wheel-HP after applying all his mods, then looked what HP two 993's did on that dyno the same day, compared that to the 'catalogue HP value' of a stock 993, assumed both those 993's were making exactly stock crank-HP and then calculated from those numbers what the dyno-efficiency for "WHP to crank-HP" would be, then applied that percentage to his wheel-HP measurement to convert it to crank-HP, got a value and finally compared that number to the 996's catalogue crank-HP value and decided the difference between those numbers would be his 'gains'. Those are a LOT of inaccurate steps and a lot of assumptions there, so those numbers should be taken with a huge grain of salt. Also, claiming 50hp vs 13-21hp gain are wildly different numbers. When you make big claims, always make sure you can back them up first.

You’ve got to be very careful when claiming 50hp increase when using nothing but a butt-dyno. That’s why it is important to have a before and after data that can be checked. It is quiet possible to gain that much if some or most of those parts were already in bad condition that caused the engine to produce less than stock horsepower. A clogged or damaged converter will choke and engine enough that when a new “high flow” unit is install, a power jump is felt. The owner will think the results are the installation of the new “performance” converter when in reality a goo used one would have resulted in the same improvement. Same goes for the throttle body too. Something is off on it (throttle not opening all the way, one of the sensors is inaccurate or the idle air circuit is carbonned up and not sealing or clogged. A replacement of a good used or even new OE unit could have easily resulted in the same improvement. Re mapping the ECU removes the safety factory that the factory built into the programing for situations where things are not ideal (bad fuel, high altitude, etc.). When a car is near stock 9and this car is), what a tuner calls “optimization” is the trimming of the safety factor. Make sure you understand this when you ask a tuner to give you more horsepower.

The reason why I didn't remap after IPD and TB install was because my tune was already mapped for this, prior to the installation. I was going to purchase all these components together and FVD sent me the tune for all including larger TB and IPD. I did it in stages due to financial constraints.

Your observations are correct. However, the safety margin in these cars is quite high. FVD is one of the oldest German tuners of Porsches and I have confidence in what they do.

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wow that is the price difference of a 996TT and that for marginal HP and torque increase You should have invested in a piggy back ECU. Or still do. Then you could have really done some proper tuning for your custom set up in relation with your engine. Then you can go much further on timing and fuel injection then there is margin for in the stock ECU. I hope you also did the small investment of a brand new MAF in order to get the most out of it. Do not forget that the max bhp and torque gains are not those at peak level but somewhere throughout the rpm range. Makes for a quicker feel of the car. But still marginal. without a comparable before and after dyno run your claims are just smalltalk. Sorry I guarantee you that the same effect of the 82mm TB you can obtain with a sprint booster. As in essence it will in the same way amplify the amount of air going in. Only at WOT there is a difference of the GT3 TB being somewhat bigger. I had the ipd standard and competition plenum side by side. Their diameter at the inlet side is almost identical. So doubt if there will be that much difference. Do not misunderstand me. I have done similar tweaks. I had both of the plenum installed on my car. Also with x-pipe. I decided to sell the competition plenum with big TB and keep the standard. The most advanced setup was just too loud. Performance was okay. Running now with top gear 200cell cross-over cats with cargraphic mufflers and I think I hitted right the sweet spot. Lots of torque ... and most of all fantastic refined boxer sound. No need for a dyno for that.

That is not the price difference between 996 and 996 TT. Not in Canada. Do you care to elaborate on ECU upgrades?

Well it comes close to the difference ... omg almost 10k$ invested ... boy that marketing machine works good ecu stuff i am not there yet.still need to test if it is what it is. Problem is I have a family a more then full time job and no spare time to check it out.

996TT in decent shape are $60K in Canada. With all my excessive upgrades and the price of the vehicle I am not even close to that figure. I am not sure what other upgrades you are referring to? ECU, MAF and sprint booster. Don't understand how MAF can improve performance. It is a sensor only. Please explain. Furthermore, You are suggesting that I should have done a dyno to back up my claims. First of all, I am not making these claims for bragging rights. I am just trying to help others with their upgrades. It is up to everyone to believe it or not. I chose to believe others who claimed performance gains and I am happy that I did. At the end, you said that you did similar upgrades but no dyno. No need for dyno. Then, why would I dyno my car? To prove everyone that I am telling the truth?

Relax man!!! It is your money no big deal. I dont need the dyno. My butt doesnt feel the difference. But i compared the bigger TB with the sprint booster and it has the same effect under 80% of the throttle range. Just i think that if you spent this amount of money you should have done a before/after dyno. Now it is only speculative. Guessing and freewheeling. Now next thing put a decent suspension on the car. Much more cost effective then 10k for 20bhp. And boy your butt will notice how much better it drives. On top of that put some recare pole position bucket seats and and get some nice light weight wheels. Makes your car even faster due to less (rotational) mass and that for less then half the price. At least that is what my next project is.

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You've post hard number claims with no hard proof. Making such claims requires some hard proof to be believed.

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I�m a doubting Anthony. I base my views on years of modifying and drag racing cars. Very few mods provide the improvements in acceleration they claim.

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I am as well. I had this exact setup (gt3 throttle body and ipd competition intake with aftermarket exhaust and 200 cell cats), minus the custom tune, and was not impressed. It sounded great, but likely any gains were placebo. Scott from Softronic was the one that explained it all to me, and I�m not a believer in IPD since. I suspect the tune/remap is what the OP is feeling, rather than measurable gains across the rev range.

I am not changing suspension. My car already has a nice one. With light weight wheels. The next upgrade is sport headers and maybe light weight cam shafts.

That's not the exactly same setup. Not even close. l have done a bunch other things which may have contributed to incremental gains. Everything counts.

I agree with you. Somehow this exact setup works for me. This car is far more capable than the stock car. I know that because l have driven both.

I think you're mostly just convincing yourself at this point. In all honesty, good for you and i'm glad your mods leave you satisfied with the results. It's just that most here will simply not accept your claimed numbers without proper before-and-after testing on a calibrated dyno, and rightfully so. You don't have to defend yourself against that or feel attacked by it, that's just how it works.

Hey user 63031, I appreciate your sarcasm. It's healthy. You probably think I am a nutcase with unlimited funds who has no better things to do in his life than blowup his money on senseless upgrades. You sure are right about the nutcase part. Not right about unlimited funds and senseless upgrades. I am OK with that. I am used to being doubted in my life. This post is not meant for those faint of heart. For those of you who need a proof for everything, I know that even if I had provided a black on white proof of 50 HP gains most of you would say that it makes no sense to spend this kind of money for mediocre gains. What is the point of me doing a dyno? I don'f defend myself. This is a healthy discussion we are having. I enjoy it. Keep it coming. The whole point of these discussions is to learn about other people experiences. Without these threads, I would not know anything about these great cars.

There's no sarcasm in my posts, and none intended either, just my honest opinion and I'm honestly glad you're happy with your mods. All we're saying is that without comparable dyno runs, the numbers you mention are absolutely meaningless. Nothing less, nothing more.

Seeing the itemized list sure does sting a little. Sure the car sounds wicked and im sure the driving experience is vastly improved over stock but man can cost really get out of hand Doing the install yourself would help considerably in this situation but for most of us who try different setups until we get to the one we really like, trial and error can cost $$$. All this potential cost really makes me wonder how much $$ i'm comfortable putting in my car considering its potential for an even more costly unexpected rebuild.

Oh you didn't see the whole list including repairs and upgrades. This is just a portion of costs spent on performance upgrades. It's a hobby and a project at the same time. Does it make sense from the cost vs the value of the vehicle perspective? No it does not! People spend lots of money on their hobbies just to make them fulfilled. Work in progress continues. I am going to doing as much work as possible myself, time permitting. It is fun and makes you fill like you have accomplished something.

I don't believe in faith based performance claims. Light weight camshafts? Who sold you on that idea?

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^^ My thoughts exactly! Sounds like a disaster waiting to happen...

50hp? i doubt you have gained more than half that honestly... and yes i have all of these mods on my car the sound is better for sure, the throttle is also a bit but the sprint booster does more of that than the rest i think

The reason that I repliek earlier in this post is that I experimenten with more or less similar upgrades in all sort of variations. I do not believe in these performance gains. But i concur they sound great and drive great too. To get the most put of tour upgrades you need to put your car on the dyno an iteratively fine tune your own tune. Nothing remotely written can get the maximum out of it. To be even more perfect you should dyno it on the road with real road conditions. Furthermore the ECU is too limited to get the most out of it. For example In the higher rpms timing and fuel injection is regulated to protect your engine. The safeguards are pretty conservative. For your individual case there is much more to get. But you will need something to override the ECU.

Sounds like a logical upgrade to me. Less weight, higher RPM.

I don't have any experience with sprint booster. Do you care to elaborate. I am pretty happy with the outcome of my upgrades so far. I will continue to seek for improvements. Any suggestion is welcome.

I totally agree with your post and will try to find a local tuner to facilitate that.

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If you turn the booster on you can see a big difference in the throttle, since these cars aside from 99 are by wire there is a delay from when you push the throttle and it gets to that point, the sprint booster removes that thus making it more responsive. It wont give it anymore power but it changes the driving experience for sure. Even with all these upgrades if i put the sprint booster in race the throttle response is noticeably different.

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But, is it really worth the $300.00? If one is rewriting the DME you should be able to produce the same result...

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Oh boy! How much weight do you think you will lose with those camshafts? Camshafts are basically round bars, the rational mass is very close to the center of the shaft therefore, lighting it will not going to make a difference but it can weaken it. Your max RPM is limited by the ECU but even if it wasn't, the engine needs to be able to breath beyond the rev limiter in order to make any more horsepower. If you'd ever done a dyno on this car, you would be able to see what is happening with the curves at the rev limiter. If it already started to fall off, the engine is struggling to pump air. If you decided to just raise the rev limiter to gain more HP that will not work either if the can't handle it. You have to be very careful with piston speed too. you don't want the piston to rip apart at the wrist pin.

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you probably could but it would be like that all the time and most people wont want it set super aggressive all the time so this is far better as you can turn it off with the click of a button and how many people can do a custom DME tune? finding one is not as simple as people throw around on this forum for sure