I'm going to install an Accufab 75mm throttle-body/plenum combination in my 2001 GT. I will also be adding a CAI to accomodate the larger throttle-body. Is it preferable to go with a composite version (K&N) or an aluminum one (Steeda and C&L). I called C&L and they claim that the air moves so quickly through the inlet tube, that there is no time for it to heat-up. I like the looks of the C&L the best, but I don't want to sacrifice horepower for looks. Any advice would be appreciated.
Also, does anyone know if a tuner (Diablo Predator, Superchips, etc...) will adjust the computer for the addition of a throttle-body/plenem or CAI. If not, I want to save the tuner purchase until I get my 3.73 rear-end installed.

Thanks,
Stangvert

 

I've heard that going with the 75mm over the 70mm might actually have a negative affect on performance. I think this is a point that is contested often but I ran across it before when I was looking at TB's.

Not sure on the inlet tube material, maybe the air does move to fast to get heated but I would prefer a material that doesn't conduct heat just to make sure it's not an issue.

You'll get more out of the CAI,TB,and plenum install with a tuner but if you're going to do more to the car you could wait until then and you will still see a performance increase without the tune. I had my CAI running for a while with out a tuner and it took about .20 seconds off of my ET from the stock set up.

 

I dont know what the advantage would be between the different types of CAIs on the market. People seem to be pretty happy with all the brands you mentioned and the HP gains are fairly close from brand to brand. If you want the C&L, you're probably safe getting it.

As for the tuning, a tuner can take the intake parts into account, but your car will run fine with them even without a tune (that's how my car is running right now). If you're getting new gears soon, you can certainly wait until then to get the tune if you want.

 

I told a couple of people that. you may have been one of them. Basically, your engine can only take in so much air in stock form, and increasing the diameter of the TB to 75mm only pushes the intake volume past what the engine can posibly use. Because the volume of air traveling through the engine remains constant, the larger inatke actually dereases the velocity of the air, which can hurt performance.

The 75mm TB works better if you are changing the internals of the engine or adding a supercharger. Doing so lets the engine use more oxygen and it can then use the added air intake from the 75mm TB.

 

Good rule of thumb is to use materials that minimize heat transfer. Velocity through the tube may be a factor but the fact that the metal tube transfers heat more readily will also be a factor regardless. Especially at lower throttle angles.
As for what works, and what does not, I can tell you that Dale at Axcelerated Motorsports has a ton of Mustang experience, and is more than willing to share it with you. He has a chassis dyno and runs mostly Mustangs.
http://www.axceleratedmotorsports.com/index.cfm
I just had my car dyno-tuned this past weekend and spent the whole time picking his brain about the value of certain mods. I think he'd be a great source of info for you.

 

I believe you were my original source on that. It makes perfect sense to me but I have heard people argue the point. I wouldn't have thought about it if you hadn't mentioned it and would have just bought the biggest TB I could. Now I think I'm going to get the 70 and be done with it.

 

I did quite a lot of research in regards to TB's. As mudshuvel (+1) said the 75mm will harm performance. I have the K&N with a 70mm TB + plenum. Runs faster through the rpm range however I have ended up with a slightly rougher idle which I must add is not a problem at all. The increase has been actually quite suprising.
IMO be it plastic or metal the CAI will allow cooler air to be sucked into the engine from a nice cool location through a less restrictive filter and the TB will allow it to pass even faster to where it needs to go.
I would go with which looks cooler, or what someone recommends, or draw out of a hat. Either one will increase performance and make the engine whoosh and whistle.
I say go with the 70mm TB but when you do go with the plenum as well. It will be a quicker, easier install, look more complete and compliment the TB as it should. Just watch for paper stickers stuck to the bottom of the old throttle body falling into that dark hole when you take it out and have a drill ready to drill out the old screws from the throttle position sensor because HOLY LOCTITE!!!! Install took me 30 minutes and I am a novice. Will post install instructions for all my parts soon.
Good luck with your decision.

 

Tricky,
Awesome info and pics. I've been admiring that Accufab TB/plenum combo for a while now, even with the steep price. Sounds like you definitely feel the increase. Where is it most noticeable, off the line or higher in the revs??? I have bought the "Improving 4.6 liter dyno performance" and several other 4.6 books that state that the stock GT 2-valve engine will pick-up about 12 horsepower with the Accufab TB/plenum combo. Up to 17 horsepower with a supercharger. The Accufab gets an extra 2 horsepower or so more than the other plenems. Funny thing is they state the actiual HP increase is identical with both the 70 and 75mm TBs with the Accufab plenum. They state that you should definitely go with the 75 mm TB if you are going to supercharge, but it doesn't matter if you naturally aspirate. My only decision now is the 70, or 75. I don't plan to supercharge, but who knows down the road.

Thanks,
Stangvert

 

I still say go with the 70mm. As far as noticable performance is concerned the pick up is noticable through all the revs, however what is more noticable is the way the revs rise so much faster. I want my mid pipe installed now. MRT-H with high flow cats should see even more of an increase and will hopefully help drop the revs a little quicker. That is where my current setup is failing me at the moment. Failing however is a strong word and its not a problem but something I am out to change for my own satisfaction.
You will find a much quicker pick up, its not through any specific rev range though, its the whole range. Best way to describe is if you close you lips and with a little hole breathe in hard then try again with that hole larger (perform in front of mirror so you can see what you look like-ha ha).
I would also reccomend you consider install of TB + CAI at the same time. Just be extra careful to photograph the setup before you attempt install.
If you have any questions or concerns regarding the install or if you want additional info please PM me.

 

I have read through all the posts here. and some of the stuff I agree with and some I don't. I too have always believed the thought pattern that leads one to purchase a plastic CAI, due to the heat transfer issue. If the engine is hot then it is going to heat up the CAI, right? Well based on my experience over the last couple of months, it isn't entirely true. I understand the physics of thermal dynamics and agree with them, but (in my case ) the dynamics are working in reverse. Let me explain

Last month Indiana had a mild month of 40 degree weather. Having purchased a relatively cheap aluminium CAI (though i capped it off with a conical K&N filter) I have been opening the hood to check it frequently.
I found something that surprised me. After relatively hard driving, I opened the hood blipped the butterfly plate to listen to the intake noise. While doing so I rested my hand on the CAI. It was Ice Cold. The air coming in from the fender well was cooling it off. So with thermal dynamics, this means that the CAI was actually cooling off the engine compartment.

Now I know that this is winter and in summer it will be 90 outside, but still if the CAI is 90 then that is still a hecuva lot cooler then the engine.

This is my experience. If you do buy it, OK. Just thought I'd put it out there.

 

Good post.

I think it's case in point why the materials used in a cai is not really as relative as the plastic cai manufacturers would lead you to believe. Sure, at lower speeds it may get a few degrees cooler than the metal ones, but guess what??.......you don't get the max effects from cai's in the lower speeds/rpms. The true benifit from cai's is at higher speeds and air intake. The IAT will drop significantly the faster you are travelling.

So, basically in my opinion, the few degrees of heat you may gain will only be there when the cai isn't even efficient anyway so it's a moot point. So Stangvert, buy which intake will be more visually appealing to you when you open the hood.

 

I just purchased a C&L True Flow pipe to mate to my BBK 65mmTB and C&L MAF. I was told that aluminum actually dissipates heat better than plastic. The guys who told me this are what I consider experts among experts. Check them out and call them if you really want to know more!

http://www.svpu.com/

 

This is quite true, however what was happening was that heat from the engine compartment was being transferred to the intake air. In absence of the intake air flow the metal tube would rapidly stabilise at the underhood temperature, the air flow was sucking that heat from the tube, cooling it as sort of a reverse intercooler. Fact is that the intake air was being heated--probably not enough to really affect anything, but heated nonetheless.

As for the metal vs. plastic debate, plastic is better.

This is somewhat counter-intuitive, but as pointed out above the reason the aluminum intake felt cold was because the intake air flow was removing heat from it (and the engine compartment). Plastic pipes do not feel as cold, or perhaps cold at all, because they are not transferring [as much] heat to the intake air--plastic is a far better thermal insulator than aluminum, that's why they use it for handles on sauce pans...

 

Thanks for all of the advice. I just installed a K&N FIPK and an Accufab 75mm TB/plenum combo. Wow, what a difference. The car feels stronger at all speeds & revs, but over 3000 RPM, the thing is now very strong. My buddy who helped me install and I were both very impressed. A little dissapointed that the Accufab TB/plenum came without any instructions or parts list. For $400, they should print something out. It's a very nice piece of equipment though. The K&N FIPK seems of very high quality too. Once I burn up the current tank of gas, I'm going to install a Diablo Predator tune, and that will be it for the year.

Next year, 3.73 gears and a MRT H-pipe with high-flow cats. We have strict emissions tests here in Maryland, so I'll have to get a pipe with cats, unfortunately. Anyone know if installing an h-pipe with high-flow cats is going to increase exhaust loudness any further?

 

Just a note for those installing a new throttle-body. You must be sure to adjust the TPS (throttle positioning sensor) or else you can get bad performance after the installation of a new throttle-body. Accufab has a nice article about the adjustment at http://www.accufabracing.com/article_1.htm . My initial reading was way off, so if I didn't do the voltmeter check and make the adjustment, who knows how the performance might have been.

 

Would there be any benefit into getting a cobra TB rather than the one designed for the 2v engine?

 

You cant put a cobra TB on a SOHC 4.6. All 4v cobra's have a dual blade TB which is oval shaped as compared to the round one on a 2v. It just wont fit.

On the CAI debate, I ran a C&L trueflow on my cobra. Its a thicker metal and a quality piece. The air going through the intake tract is going at such a speed that really it doesnt have time to heat up. After a pass at the track or something even during the summer, I could open the hood, feel the intake tube and it was much much MUCH cooler than the engine intake manifold itself. I say go with the C&L, its worth it.