Throttle bodies, cold air intakes and headers

[Tnmustcobra]

I am wanting to get a little more out of this 4.6L 4V engine and have been looking at the aftermarket throttle bodies. I see that Accufab makes one and that BBK makes one. The Accufab is a 70mm whereas the BBK is 65mm. From the installation instructions for the Accufab I see that material has to be taken off the plenum in order for the Accufab butterfly to clear the plenum. The BBK throttle body requires no fabrication to install. I like the easy install, but from what I hear, the Accufab will deliver a little more horsepower than the BBK unit. I was wondering if the installation of a spacer between the throttle body and the plenum would solve this problem so the Accufab would have clearance without grinding the plenum. I also plan on getting another mass air sensor and a cold air intake. Most of the cold air intakes won't fit with the strut tower brace still on the car. I prefer to keep the strut tower brace on the car and wonder if anyone has a cold air intake that does not require removing the strut tower brace, other than maybe for installation. Also, planning on long tube headers or shorty headers and wanted to know what everyone is running on their Cobra.

Thanks,
David Morrison

1997 Mustang Cobra
1987 Porsche 944 (NA)
2004 Ford F-350 Dually
1988 Mustang AV8SS Unlimited race car (sold)

[cvalois1]

The JLT Carbon Fiber CAI fits with the Maximum Motorsports STB The intake tubing is oval shaped from the TB down to the turn into the fender well, where it becomes round.







There was some minor modifications made to the rubber elbow JLT supplied to make it fit nicely. The hp gains are minimal. A larger TB on a basic bolt-on NA set-up will also show minimal/negligble gains (not worth the money IMHO).

[Tnmustcobra]

Thanks for your info. The 4V motors are not easy to get any "good" HP from these bolt on parts. It seems the only way to gain decent HP is by adding a supercharger. My guess is adding Throttle body, Mass Air, Cold pipe and some headers may yield an additional 25 to 50 HP ...with an offroad H-Pipe. Sometimes I wished I had a 95 model with the 5.0L. I currently run an offroad H-Pipe, K&N air filter, 3:73 gears and chip. Just need extra HP to chase down 03' and 04' Cobra's down the straights and the 2000 thru 2004 ZO6 Vettes. Got the handling and brakes modified and can get up on their bumpers in the corners, only to have them pull better down the straights. Might change the rear to a 4:10 to help off the corners.

Any other thoughts about getting some good HP without adding the supercharger?

Thanks,
David Morrison

1997 Mustang Cobra
1987 Porsche 944 (NA)
2004 Ford F-350 Dually
1988 Mustang AV8SS Unlimited race car (sold)

[nckissfan]

replacing the MAF will not gain you much, unless you are supercharged. I say keep the money for something else. Get some pullies, they help squeeze out some horses. As for CAI, I am running the upper and lower pipes from Western Motorsports. They fit under the stock stb. I didn't know that the JLT would fit under the Maximum stb. That is cool. Adding longtubes helps in the hp department, but steals a little from the tq department. The 4.10's are awesome in these cars. I have them in mine, and love them, really opens the car up. You could replace the drive shaft with an aluminum one. That will free up a lot of weight, and strain on the drive train.


shedding weight is a good way of gaining on the competition. You could rear seat delete(if you don't need it).

[Tnmustcobra]

I don't know if I want to go with underdrive pulleys since that will slow down the water pump and run into possible heating issues. I like to open track this car and I currently do not have any overheating problems. I already have the rear seat out of the car. I have all the MM stuff (coil overs, control arms, CC Plates, panard bar, etc...). I have thought maybe the 4:10 gears would help and also am considering the Aluminum driveshaft and also an aluminum flywheel. I will probably wait till I need a new clutch before I get the flywheel though. I don't know if 4:10 gears would reduce my top end enough to max out on straights like at VIR or Road Atlanta. I was hoping to get more HP or TQ and still keep the 3:73 gears. I just don't want to spend $4000 right now for a supercharger...but may have to start budgeting for one. Anyway, I pretty much have the handling and the brakes where I like them and now am trying to look at the motor next.

David Morrison
1997 Mustang Cobra
1987 Porsche 944 (NA)
2004 Ford F-350 Dually
1988 Mustang AV8SS Unlimited race car (sold)

[cvalois1]

David, is your car primarily daily driven with ocassional track use (road course and/or dragway)? The 4:10s would be good for the street and dragstrip (0 - 100mph) but probably not as good on road courses, as you'd loose some top end in the straights and depending upon the gearing in your tranny is stock.

I have 3:73s and think they're decent for the road courses, but I started to notice I'm topping out at 130 - 135mph in 4th gear at 6250 - 6500 rpms and shifting into 5th at the point doesn't add much. I've actually been thinking of going down to 3:55s to gain a little more on the top end. Like you, I've made suspension and chassis upgrades to keep up with the stock 385 - 405hp Z06s and similar type cars.

The big advantage those cars have are they are well balanced and weigh less. Like NicK said above, try reducing weight, starting with the aluminum DS and a rear seat delete and maybe going with a lighter weight battery and/or relocating it to the trunk. Anything to reduce rotational mass in the drivetrain, wheels and brakes helps considerably. From there the weight reduction can get even more expensive, such as stripping your interior and going with lightweight race seats, tubular k-member, a-arms and coilover suspension.

By the time you do all that, you could probably buy a decent supercharger kit. It just depends on what you want to do and how much you're willing to spend. Good luck

[Tnmustcobra]

The car is garaged for the most part and primarily is used for open track and also am contemplating some TT with NASA in 2009. I bought the car new and it has 33,000 miles on it. The first 3 to 5 years had some driving to work and around town or an occassional trip out of state. I ran NASA HPDE 1,2 and 3 for about 3 to 4 years before I built the race car (1988 coupe) and raced in NASA American Iron Extreme and AV8SS Unlimited. I will still take the Cobra out on the street for some playtime or to check suspension adjustments. I tow the car to the track. I know a stock 96 thru 98 Cobra with the 305 HP will not top out in 5th and I would always just run it up to 4th gear on the track. After installing the offroad H-Pipe, 3:73 gears, K&N filter and the chip, the car would pull a little in 5th, but I still was able to keep it in 4th at tracks like VIR and Road Atlanta, which have some pretty long straights. I also was running in the 130-140 MPH range on those tracks. My thinking was that if I could get to around 400hp (at the flywheel ) then maybe I could pull 5th on some of the straights without having to go to the 4:10 gears. Now that I have all the MM suspension installed (coil overs, tubular control arms front and rear, CC plates, panard bar, Koni DA, etc...) I expect to be able to go into the corners a little faster and come off a little faster as well. I already have the rear seats and trunk panels and carpets removed and since I have the MM suspension parts, my weight has dropped a little. I could probably take out the AC stuff and get some lightweight race seats (would like to have a seat for passengers). Some of the weight saved would be offset by adding a roll cage. I am running CCW wheels and run a competition tire like the Hoosier or the new Goodrich R1, so wheel and tire weights are lower. I still know those Vettes will be fast down the straights. I am aggressive on the brakes and can go deep into the corners and roll into the the throttle coming out of the corners as best as the car can grip. I try to find the line around the track and drive my line. I can keep pace with these Z06's under braking and in the corners. I just need a little more out of the motor to at least maintain speed with them down the straights. Then, maybe I will be able to get past them and pull away with late braking and rolling thru the corners faster. I am only talking about stock C5 Z06 Vettes..not the C6 Z06 Vettes.

I will do what I can do to reduce weight, but still am trying to figure out how to get more HP/TQ out of the car. I was hoping that by posting on this forum, that I might get some advice on getting more out of the motor. These mod motors are not easy or cheap to get more out of them and sometimes I wish I had an earlier model like a 95 with the 5.0L that is so easy to put in cams and stroker kits. Looks like not much I can do to get a lot out of the motor without spending a fortune. I had to sell the race car because the budget to run that car was more than my wallet could handle, but it was fun and worth going broke! Guess I'll go with the aluminum driveshaft and a throttle body for now and try to lose some weight off the car. My main obsession is to get the Vettes.

Thanks,
David Morrison

1997 Mustang Cobra
1987 Porsche 944 (NA)
2004 Ford F-350 Dually
1088 Mustang AV8SS Unlimited race car (sold)

[cvalois1]

The addition of LT headers to your current set-up will probably show the most gains. Forget shorties. With the LTs, you'll need a new mid-pipe too. You might see 320 rwhp. Maybe consider an aluminum flywheel next time you have the tranny out or are replacing the clutch.

If your goal is 350 - 400 rwhp NA, you'll need to spend more than just adding a supercharger, unless you have experience or know someone to help you pull your motor and do machine work. It sounds like you already know this.

On the cheaper, not so evasive side you could pull off your upper and lower intake and sent it out for porting and polishing, which will probably run anywhere from $500 - $1,500. From there, it gets more evasive, dropping/pulling the motor, pulling your heads off and porting them from $1,000 - $2,000+ and you might as well factor in a valve job while your at it. While the motor is out, that's the time to the cams too ($750 - $1,500).

Then while everything is off the block a big bore and/or stroker kit could be done ($1,500 - $2,500). If you go the ported and cams route, you'll also probably want/need a set of larger 30lb injectors, better fuel pump & new tune ($500 - $1,000). It gets real expensive really quick. Ball park figures to do all this yourself is $5,000 - $7,500, $10,000+ if you buy all the parts and pay someone to do the work.

For me, keeping up with the general maintenance open tracking the car (tires, pads and rotors) and the cost of HPDEs is considerable enough on an annual basis, nevermind owning and maintaining an actual race car. Seat time at the track (not mods) is the best money spent IMHO

[cobrabitn]

You can get 375- 400 rwhp if you change the heads on your Cobra along with a couple of other mods. You will need the FR500 heads to make this happen. If you want a naturally aspirated engine for the track, this is the way to go and I recommend this for what you are wanting to do with your Cobra.

P.S. I also recommend not going any lower than (numerically higher) 3.55 gears for the track especially at VIR.

[Lumpydogs]

Tony,

You always give good advice but what about the no lower than 3.55 for VIR? My 4.10 was fine at VIR last year. Just curious.

[puzzle13]

You need to talk with Burke concerning all of your questions!! His car is going through a huge process concerning the engine, FR500 heads that have been completely ported, the motor is built, he has 3.73's in the back and is topping out at 130 - 135 at 7000 rpms, and he wants more. The long tube headers are a problem with the 97's due to transmission conflicts. If I understand correctly you can't remove the tranny without removing the headers, and to remove the headers you have to take the engine loose. As I said ... contact Burke at bdbadcobra@hotmail.com ! He is tracking the car a lot and it is one fast Cobra!!! The throttlebody issue ... you will have to grind with both throttle bodies to get full performance, which is not a bunch without a supercharger. With the BBK you have to grind away at the plenum so the openings match the BBK openings. It will work without this, but won't work to its full potential. Again ... contact Burke for first hand info as there are complications with the FR500 heads also, but his car is in my garage being put back together and we can send you pictures. Yes, he also had fun getting a brace to fit with his JLT cold air. First hand knowledge is always best.

[cobrabitn]

You have to see where you max out in 4th gear when you are running at VIR. My 5.0L is maxing out at 120 mph and when I hit 5th, it just dies. Having 4.10's is good for the street but if you are maxing out at VIR and still have asphalt left then you should go to a higher or even stock 3.27's. You don't want to waste the power you have by holding steady. JMHO

I was going to say that Mike about Burke but I didn't want to put his e-mail addy out there with all of the spam bots we have visiting our forums every day.

[Tnmustcobra]

Lots of good information here and I appreciate everyone's input. I will look into some of these mods and even though the performance heads and cams seems the way I would like to go, I'll have to see how the budget works out before I can make those purchases. I will probably wait till after the 2009 season ends before diving into the motor. I am also thinking hard about what I can do to lighten the car and some of those things are take out the AC, replace the leather power seats with some good lightweight race seats (will add harnesses and roll cage) and possibly change the windshield to Lexan. Another thought is to purchase some dummy doors with the roll up handles from the Mustang salvage yard and gut them out and replace that glass with lexan or equal. I am definitely getting the aluminum driveshaft in the next week. I see some NASA events at VIR and Road Atlanta coming up this spring and will definitely see how the car has improved since all the MM suspension goodies are installed. I will watch 4th gear down the straights and see what RPM I am running to see if a gear swap might be considered. I will talk to Burke and see what he can tell me about all the work he has done to his Cobra and get some good feedback from him before I start anything inside the motor. In the meantime, if anyone is going to be at VIR or RA around March, let me know and we can meet at the track!

Thanks,
David Morrison

1997 Mustang Cobra
1987 Porsche 944 (NA)
2004 Ford F-350 Dually
1988 Mustang AV8SS Unlimited race car (sold)

[puzzle13]

Who are you running with in March at VIR? Or did you mean CMP? Burke will be at CMP and his car should be quite quick! He pulled the A/C, cruise control, fiberglass hood, etc. I told him you would email him and he said he would help as his modification list is quite long!

Tony ... I was worried about that too, but Burke has nothing to do these days except hang around in my garage, so I figured a few extra email might keep him busy!!

[Tnmustcobra]

I was looking at the NASA mid-Atlantic schedule and they have dates with VIR full course on 2-21/22-09 weekend and then again on 3-28/29-09 weekend. I was thinking the March weekend would be a little warmer weather and the last time I went to VIR in February it rained. The NASA Southeast schedule shows CMP on 2-6/7-09 weekend, then Road Atlanta on 3-14/15-09 weekend and then back to CMP on 5-2/3-09 weekend. I really like VIR and RA as they are my favorite tracks. I have not been to CMP since it was reconfigured and I bet it is really fast now. I guess the "Kink" is gone....I really liked that feature! I just looked up the CMP schedule with the Cobra Club March 14/15 weekend and that is tempting, too! I also noticed Burke was running Tech and Scott Whitehead was classroom instructor. Would be good to see what Burke has done to his Cobra and maybe run in the same group. I also could say hi to Scott....we "bumped" into each other at Nashville Superspeedway a few years ago. Scott is really a cool dude and he helped me with my set up on the race car. Last time I came to CMP and ran with the Cobra Club...back in 2006 or 2007...I think... I helped instruct and might try that again if there are any openings for instructors. All these dates are so close together it will be hard to make a decision.

David Morrison

1997 Mustang Cobra
1987 Porsche 944 (NA)
2004 Ford F-350 Dually
1988 Mustang AV8SS race car (sold)