Hello, I am looking at getting a little more air flow into my 302 but I don't want to buy a new high flow throttle body. My 302 is an 86 model and was wondering if the throttle bodies ever got bigger through the years or would it work bolting on a 351w one? If the 351w one would work, do you have to bolt on the upper intake too off of a 351w? Thanks for the help, I need a little extra boost for pulling my 5th wheel. I all ready have a high flow cat with a high flow exhaust, mallory ignition, and K/N filter kit. Thanks in advance guys.
Dustin

 

Dustin...

Your stock EFI 302 truck intake flows far, far better than the 351W EFI intake does, keep it on there.

Both stock throttle bodies are the same size for the 302/351. Somewhere around 47mm I believe. I don't think I'd install a larger unit with the stock cylinder heads...they are trash nad you'd gain next to nothing powerwise. I'd just port and polish up the stocker for a bit better throttle response.

If you need some power for pulling that 5th wheel I'd start with:

Full Tune Up - Plugs, wires, fuel filter, PCV. Maximize what you have already.

Long tube headers - more torque and hp throughout the RPMs

Underdrive Pullies - Quick and cheap power increase. For sure install a larger 130A alternator if doing this.

Bumping ignition timing - 11-14* depending on gas used.

Adjust fuel pressure - An adjustable regulator will allow you to lean the truck out a bit making more power. Most vehicles from the factory run a bit rich.

After this, its time for some cylinder heads that actually flow and can make a decent amount of power. GT-40 irons from 93-95 Cobra's can be picked up for ~$400 and will gain an easy 20-30hp...more is you get them lightly ported and decked to maximize flow and bump compression to close to 9.5-9.8:1.

After that I'd go for a mild cam (204/212 .450" 114-116lsa) and some roller rockers. That would pick up a nice midrange power once on a roll and still have bottom end torque for towing.

IS your vehicle a 5 speed manual or 4 speed auto or 3 speed auto?

 

A fifth wheel is a lot of trailer for a 302. Unless you are running full throttle already, a bigger TB won't help. Look at the suggestions above and consider 4.10 gears, if you don't already have them.

Jim

 

That's exactly what I asked what transmission is behind his 302. It if is the 5 speed that is going to be better for towing as it has a decently low 1st gear. If you are running either auto...man I'd seriously consider running a 4.30:1 gear if haven't got the low gear set in your AOD.

 

Unless my 351 isn't stock the throttle bodies are about 10mm larger than the throttle bodies on my dads 302.

 

Hm...can anyone measure the stock 351W TB?

If it's larger...I may step up to that as stock parts are pretty cheap. I just don't see them being different as BBK/Elelbrock ones are twin 56mm and twin 61mm sizes for the 302/351.

 

Why is a 302 efi intake better than the 351? They look the same. Do they interchange? I have a 351 but I'm sure not investing in an edelbrock$$$

 

vman...

Yup the Edelbrock is pretty expensive but a very nice piece. You'd easily gain 10-15rwhp or more depending on how modified your truck is.

The stock 351W truck intake has the same tiny ports as the 5.0 HO Mustang intakes. It sucks, pretty much being blatent.

The 302 truck intake is far, far larger. The Holley Systemax II intake system is based off the truck lower. I'd dare to even say it is a bit too big for the 302 with the small cams and junk heads. The ports on it are massive. Many people use the truck lower on supercharged Mustangs with a box upper.

Now I need someone with their truck by them to measue the STOCK 351W throttle body against the STOCK 302 throttle body. I still think they are the same size, but pfogle thinks they are different and I am beginning to side with him...I just need some conclusive evidence.

 

All that I have seen says they are the same. The reason a 302 flows better than the 351 intake is because the 302 is based off the 351, therefore designed to flow more air than the 302 needs. And you can get awesome power with the stock intake. The heads are your biggest killer. Windsor jr 180 flow twice as much air and made a hell of a difference on my truck with the stock intake system.

 

You can get awesome power with the stock 302 intake, not the 351W intake.

Yes the stock E7 heads are terrible. Any other SBF head is better...GT-40 (iron, P, and aluminum), TFS, Edelbrock, World, Canfield, and my favs the AFR's.

Anyone read CarCraft? You pick up ~100hp with a swap from E7's to AFR-165's! Yeah that is how bad the stock heads are. I'd say even the box stock GT-40 irons will give you a 30hp increase.

 

You guys need to try stangnet.com there is a guy (Thumper) there that can port E7s to match or out-flow aftermarkets. I think he does it for around $600. You just have to set him you bare E7 castings and he send you a fresh set. If I remeber right, there are several guys who have done before and after dyno test to prove how good they are.

Stryder

 

where can i find these AFR-165's (who makes them) and is it that hard to port and polish the stock heads? i was thinking about doing it to mine. i was under the impression that it is pretty simple

 

I have known about GT-40 heads, but seeing it printed here it just struck me...arent 93 to 95 Cobras 4 valve heads? How would that work?

 

$600 for port work on E7's! hahaha I'd just buy some GT-40 irons for $400 and gasket match them and I know they'd flow close to those fully worked up E7s. I have seen used TFS-TW heads sell for $700-850!

I can not imagine the full powerband of these heads being that great for performance...they are Smog heads. You do know that the AFR-165 heads at .250" lift outflow stock E7's at .500"?

But we all know that peak flow numbers are not as important as lower lift numbers. Facts are facts and box stock AFR-165 heads OUTFLOW all other box stock heads in this catagory.

Just think for a few $100 more you will have NEW and better flowing aluminum heads. I don't think you can get E7's to match the flow on the intake AND exhuast end of an AFR, Canfield, TFS-TW, or an Edelbrock. Combustion chamber on the E7's aren't too efficient, they have tiny valves, if you install larger valves you can increase flow but you can also mess up the air flow into the chamber itself.

Go read this months MM&FF, they dyno many SBF heads.

BTW, do ya have any flow numbers from those fully ported E7 heads? I am curious to know what kind of numbers those can be worked to and from .050-.600" lift @ 28" H2O.

 

84Maztang...nope on the 32valve motors. Cobra Mustangs got those heads in 1996. The 93-95 cars were still 5.0's

mpmitche... www.airflowresearch.com & http://www.airflowresearch.com/pages/165sbf_sh.htm .

You must rememeber sure you can pick up a good amount of power by porting stock heads...I'd say about 20-30 from a basic port job. BUT the shape of the runners, the chamber design, volume of the runners, etc. ALL play a vital role in the cylinder head's ability to make power. If you can go find a few recent magazines I mentioned they all cover lots about the stock E7 vs the aftermarket.

I'd lay some money that you can have fully worked up E7's and they will come close in flow numbers to numerous aftermarket heads BUT will not make the same total power any of the aftermarkets will just due to design changes, improvments, flow abilities, etc.

Run what you want, but when it comes to making the most power for the least amount of cash and not end up wishing for more...I pretty much know what to get and what to stray from BUT I am always open to more suggestions for improvments on what's around.