Throttle Body Experts
 

Gentlemen, I could use your help. I built a Cobra kit car. The engine I used came from an 89GT. The engine looked new, I bet it wasn't in the car 6 months before it got hit. It has Cobra intake, (with the cobra 5.0 logo), cam(don't know what size), Ford/Crane roller rockers, Ford headers. I took it to the dyno and was 269 wheels which equates to about 309 crank. The dyno guy said it was running a little rich. We took the air cleaner off for a run and it was still the same. He suggested a bigger TB. He frowned on a bigger MAS, said people have problems with the computer and all. I read an artical where a guy had 400 HP with the stock MAS. I have the #19 injectors which I understand are good up to about 325HP. I'm finally getting to my question. My TB is painted and has no markings. I measured the intake with a ruler and get about 58-60 mm. Not the bevel but the throat. Is this how you determine size? I would like to get a larger TB if it is going to give a little more torque. Is it possible the previous owner put the stock TB on the cobra intake? Do I need to go to a 70mm or is a 65mm better? Sorry for the rambling but I wanted to give you guys as much info as possible. Thanks,
Jim

Sounds as though you still have the stock TB on the intake. Since the stocker is 60mm.

Your best bet would be to go with a 70mm if you plan on keeping it N/A, but if you plan on adding a s/c then get a 75mm. But when you increase the TB you will need to get a bigger MAF meter, a 75mm to 80mm would work well. I've never heard of a larger MAF giving computer problems unless its not calibrated properly for the injector sizes. If you do get a larger MAF, make sure its calibrated for the 19lbs injectors, unless you upgrade those aswell.

Good luck.

Go to a 65mm TB.

You can upgrade the Mass air sensor if you want but it isnt necessary.

At your HP level IMO a 70mm TB would be too big. You would also have to grind out the intake to match a 70mm TB.

You should see about a 5-8hpgain @ the flywheel with a 65mm TB IMO.

OK. 65mm. Is the Ford as good as any of them?

accufab makes really nice ones but they are kinda expensive

Mine is a ford 65mm. And I like it alot.

So, what's the deal? The Ford book says #30 injectors with the 70 MAF. Is this true? Is there also computer recalibration if you change the MAF? Just changing the TB is $200. Hardly worth it for 5 HP. If you change the MAF and injectors and TB, your up to about $600 for 20 HP. Also hardly worth it. I'm getting more satisfied with my existing setup.

Its not worth it at all. You can have the big mass air sensors calibrated for what ever size injectors you want.

Seriously though you dont need big injectors the stock ones are more than enough at this point. A Mass air sensor and a TB wont do much for a stock engine.

Might wanna just leave it alone.

You wouldn't be gaining 20hp. from just getting bigger TB & MAM. They would benefit you...but the injectors will do nothing for you. They would make your motor run rich...which would require backing off the fuel pressure and more tuning. It's all of the little mods put together that end up making the total combination...so in my opinion...getting a bigger TB & MAM is definitely worth it. Especially if you plan on doing further mods down the road. Otherwise...I'd just leave it.

Thanks guys, you've always been helpful! Here's a pic.

http://members.cox.net/mrpink/cobra%202%20final.jpg

NICE
 

Nice Cobra mrpink! I bet that thing is pretty peppy considering how light it is. What do you think it weighs? 2400lbs. maybe? My Dad built a Cobra replica when I was about 9 years old. It was awesome! Such a head turner. I remember just cruising down the street with my Dad and guys mowing their lawns stopping to check it out and giving a thumbs up. It had a 400 smallblock in it. Being 9 years old it was a little loud and intimidating to me...not to mention the pain of melting your skin onto the side pipe while climbing out of it. Ouch! :eek:

Simi, no matter how old you are, IT"S LOUD! It weighs about 2100 pounds with 3.55 gears. My wife and son both have "snake bites" on their legs from the pipes. A lot of the guys have gone to carb for the period correct look. But living in AZ, we have altitudes from 500 feet to 11,000 feet. I've seen the carb cars farting all the way up the mountains. That's why I wanted the EFI.
Jim

Sweet car!........That thing must Haul some serious @ss.:D

NICE
 

That's awesome. You have yourself one sweet ride. I'm jealous. "Snake bites"...that's a good one. :p I'm a fan of the fuel injected route myself. Is it an automatic or stick? Any 1/4 mile times yet?

Simi, thanks for the compliment. It's all drive train from a 87-93 Mustang. I have the T5, engine, rear end, gas tank, wiring harness. Most of the other stuff I replaced. 4 link, etc. I got a 89GT at a junk yard. The guy just does Stangs. He was looking for one for me. This came in and was hit in the front. He got it @ an ins. auction in Las Vegas. It looked like the motor was brand new. GT40 crate. Put 5000 miles on it in 5 months. Oil was still at the top of the dip stick. I got lucky!

NICE
 

That is impressive man! With a GT-40 crate motor...2100lbs...and a manual 5 speed...that thing must be a frickin blast to drive! Have you raced it against anything? Any idea how fast it is? Or what you could compare it to? It's gotta be a low-mid 12 sec. car...even on radials probably.

Simi, no I have not raced it. But freeway on ramps are fun! There are about 12 of us that go on a run twice a month. Going on one tomorrow with some twisty roads. Take Care.