Increase HP and still pass smog in CA?

[Daryl]

Saving my Benjamin’s for the inevitable engine rebuild. I live in CA so I will likely at some point get a love letter from the DMV registration that will require me to get smog certified in order to get my tags. My questions are many, but the focus is this:
1. how much HP can I get/increase and still pass smog?;
2. Have to pass the visual inspection, too, so must keep the motor looking Plain Jane(aluminum heads are a dead give away);
3. Keep in mind I have the 4 cats on the exhaust system, the standard for my ‘95 Snake.

So, what are my options to increase HP over stock and still pass smog?

 

[ttocs]

it might be cheaper and easier to move

 

[Daryl]

Actually, moving may be in the not too distant future (5-10 yrs)

 

[apsmith49921]

Could have the intake ported and heads done. Look stock still. Ttocs can correct me if I'm wrong but don't ported manifolds on those 5.0 do a lot

Sent from my SM-G955U using Tapatalk

 

[Wmac]

Good set of aluminum heads as well as porting the lower and upper. Paint the heads to disguise them. There are heads that have a carb# if you need it. Look for a used 65mm t/b from ford racing to complement the ported intake and larger valves.

And of course 3.73 gears for that added punch. lol

 

[Jakespeeds]

Daryl,

The amount of horsepower you can get and remain smog legal depends on if you are staying N/A or going with an add on like a supercharger or NOS. Then its down to the components and the build. Everything needs to work well together. One of the restrictions you will need to pay special attention to is making sure it has a CARB EO# attached to whatever you use.

No the motor does not need to look plain jane to pass. You saw my engine. It passes just like that. But everything on the engine has a CARB EO#. Mustangs come with aluminum heads and blocks from the factory. So that is not an issue. You just want to make sure they have a CARB EO# or the aftermarket manufacturers name is covered up.

I have seen enough engine dyno tests to know cats really don't hurt performance it almost all cases on street driven cars. I have seen tests of factory cats that did not hurt performance until about 5K RPM. I have seen aftermarket (SMOG legal) cats that do not hurt performance at all. So depending on your goals I would not be too concerned with the cats.

Jake

 

[Daryl]

AP, Wmac and Jake,
Thanks for the feedback....
So there is a way!
1. I didn’t know that the stock 5.0 heads on the Cobra are aluminum. Now the question is whether to replace with CARB-legal heads or have the stock heads massaged?
2. I am staying N/A. So, I’m also wondering
about what, if anything, can be done to the bottom half of the motor and still pass smog?

 

[Wmac]

Gt-40 3 bar or 4 bar are not aluminum. It is expensive to have them "worked". Better off with AFR-165 or Trickflow. Trickflow requires different rockers, AFR pedestal mount allows for your 1.7 cobra rocker arms. Not sure if Trickflow are smog legal.
Keep the GT40 irons or sell them. Find an explorer intake, port the crap out of the lower (easy diy gasket match) bolt this on when you change heads and top with your cobra upper. Will look stock and add maybe 50 horse or so.

 

[Daryl]

Gt-40 3 bar or 4 bar are not aluminum. It is expensive to have them "worked". Better off with AFR-165 or Trickflow. Trickflow requires different rockers, AFR pedestal mount allows for your 1.7 cobra rocker arms. Not sure if Trickflow are smog legal.
Keep the GT40 irons or sell them. Find an explorer intake, port the crap out of the lower (easy diy gasket match) bolt this on when you change heads and top with your cobra upper. Will look stock and add maybe 50 horse or so.

Same era Explorer, ‘94-‘95?

 

[Jakespeeds]

Daryl,

I did not mean to say the stock 5.0 heads were aluminum. Meant to say that Mustangs come factory with aluminum heads. I doubt that is going to raise an eyebrow. I think on your era they were only cast iron. Someone else on here will have a better answer. I do not know much about those engines.

Short answer is you can do just about anything you want to the bottom end. But that factory ignition will only be able to deal with so much. You do not have a very advanced detonation ignition retard on that car. So depending on the chamber size of the head you will probably want to be no higher in compression that 10.5:1. You can even run a cast piston if you like. But a good upgrade would be forged. After that you just use good quality components in the bottom end. Ford built those engines to take a lot of abuse. Factory clearances and products would serve you just fine.

Concentrate on getting the coolest and highest volume of air in. And making it as easy as possible to get the air out.

Jake

 

[Wmac]

No 5 litre pushrod or 5.8 left the factory with alumnium heads. The GT-40 X & Y heads came from Ford's aftermarket division as stock replacements (FMS the FRPP) They could be bought from a dealer, but were mostly sold through the after market "speed shops"

 

[Daryl]

Wmac,
Remind me: how do you tell the difference between X and Y heads? Something about fins on the valve covers??

 

[Wmac]

No to valve covers.
Aluminum heads usually have an identification stamped on the front.
Y-303 are smog legal with carb #
X-303 are not (I think)
Both are 1.94 intake valves and 1.54 exhaust valves.

Afr-165 seem to be the head of choice. (best bang for buck)