Block questions

s_vargas54 · Jan 25, 2026

I am getting ready to start a build on my 91 LX that I put in the garage 8 years ago when my divorce happened. I am finally in a place where I have the time and money to get it going. When I parked it I had only owned it for a couple of months. It had a mild cam, some head work but from what I remember the rest was stock. The intake might have been ported but I don't remember. I live in California and smog is a huge factor. Moving right now is not an option but it is in 7 years when I retire.

I started with the idea of a 331 and a small blower. My goal is to get around 450 HP to the wheels. I am not interested in building a 600 HP motor so I wasn't really looking at Dart blocks or 302 Boss blocks. But the more I research I am torn on the need. Some threads say 450 WHP will destroy the block. Some say it will be fine as long as it's not trying to push 450 NA through a stock block.

So with this long set-up....If my plan is to try and build a 450 WHP motor with a stroker and a Vortec can I use the stock block I have and just upgrade the internals? I am not interested in putting in all this money to have the block crack. I am not planning on taking it to the drag strip. I want something that is fun to drive and sounds good. If I have to change blocks I can but in California if you swap blocks you have to go to the state ref to get a stamp so you can smog.

I am open to advice, suggestions, anything that will be close to what I am looking for. I have even considered a Coyote swap but I really want to keep it nostalgic.

Thanks in advance...

gkomo · Jan 25, 2026

Just another question to consider as a fellow Californian… how will you CARB legally run that setup from an engine management perspective? At that power level you are looking at a different MAF and injectors and how to tune them?

Not saying it can’t be done.. I have the same question for myself. I’m currently blown on a stock long lock but have heads ready to go and am stockpiling parts for the eventual motor rebuild, I’m just stuck on what I’m gonna do about bigger injectors (needed to support the higher HP) and tuning it all while staying SMOG legal.

Noobz347 · Jan 26, 2026

What referee station is going to know a DART block from an OEM roller?

The only thing the referee station is going to do is compare what is under the hood with against their list. If they see alterations from how it came from the factory there will be questions. The only answer to those questions are CARB exemptions. That monkey won't know a DART block from a 4-cylinder Toyota.

Now, start slapping intakes with the words "Racing" all over it. Some garbage aftermarket "cold air intake" and an ECU that doesn't match the one they are required to test, well... Those are all issues. Flashy aftermarket parts stick out like a sore thumb.

Do a complete, stock rebuild. Install a supercharger with a CARB exemption with paperwork. After that, it comes down to the sniffer.

You think a Coyote swap won't have the smog station crawling up your bucket? LoL

Mustang5L5 · Jan 26, 2026

Noobz347 said:
What referee station is going to know a DART block from an OEM roller?

Based on some stories i've heard....i wouldn't be so sure.

Noobz347 · Jan 26, 2026

Mustang5L5 said:
Based on some stories i've heard....i wouldn't be so sure.

I lived there for first half of my career and had to play the game.

Sure, there is maybe one wrench head in 1000 but otherwise, they know what's on the page printed with what to look for.

Headers/exhaust and intakes are a huge give away along with non OEM looking CAIs. They look for intact and working SMOG items and do a sniffer.

If they have a reason to look they will look harder.

They are not looking for differences in engine blocks. Now... If everything in the engine bay is 'wrong' (like a Coyote) then yeah... the engine block will be a question. LoL

gkomo · Jan 26, 2026

BTW i just paid $183 to SMOG my mustang. Crazy prices because "its done differently on the pre-1995 vehicles" (i.e. they actually have to do some work and hook up the sniffer probe into the exhaust). Extortion.

Would they know the difference in the block, probably not. But don't sleep on how thorough they are, even i was shocked. Like Noobz alluded to though, i'm sure having a blower (even CARB legal) starts raising red flags for them which probably didn't help my case.

Noobz347 · Jan 26, 2026

gkomo said:
But don't sleep on how thorough they are, even i was shocked.

Well you know... They're saving the world.

Noobz347 · Jan 26, 2026

View: https://www.youtube.com/watch?v=-rbO_8C0yvY

s_vargas54 · Feb 4, 2026

gkomo said:
Just another question to consider as a fellow Californian… how will you CARB legally run that setup from an engine management perspective? At that power level you are looking at a different MAF and injectors and how to tune them?

Not saying it can’t be done.. I have the same question for myself. I’m currently blown on a stock long lock but have heads ready to go and am stockpiling parts for the eventual motor rebuild, I’m just stuck on what I’m gonna do about bigger injectors (needed to support the higher HP) and tuning it all while staying SMOG legal.

I am honestly not sure on that. I am hopeful that as long as I get past a visual then I will be good.

s_vargas54 · Feb 4, 2026

Noobz347 said:
What referee station is going to know a DART block from an OEM roller?

The only thing the referee station is going to do is compare what is under the hood with against their list. If they see alterations from how it came from the factory there will be questions. The only answer to those questions are CARB exemptions. That monkey won't know a DART block from a 4-cylinder Toyota.

Now, start slapping intakes with the words "Racing" all over it. Some garbage aftermarket "cold air intake" and an ECU that doesn't match the one they are required to test, well... Those are all issues. Flashy aftermarket parts stick out like a sore thumb.

Do a complete, stock rebuild. Install a supercharger with a CARB exemption with paperwork. After that, it comes down to the sniffer.

You think a Coyote swap won't have the smog station crawling up your bucket? LoL

I very well could be overthinking this. I was doing some research and it says a new block requires an inspection and sticker just to get a smog. I am not wanting to spend $15K getting this car where I want it only to get state ref'd right out of the gate. I also don't want to run a stock block and risk it going bye bye. I am trying to stay right at or just under 450 rwhp. From what I have read that is close to the limit on a stock 302.
Dropping $2,500 on a Dart or Boss block sucks too because I don't ever plan on pushing the sort of power those can run.

If I did a coyote swap I would do it the California way and get the inspection done.

Tbh, I would prefer the 302 route. This is all new to me. My first mustang was an 89 GT but that was back in 1996. I have had two 03 GT's and currently have an 01 GT that I drive while I am doing up my 92. I am still doing research if I even need to go 331 or if I could do heads/cam/Intake with some porting and get close to the 350 mark then slap the blower on for the last 100 hp.

Mcmahst · Feb 4, 2026

Listen, do yourself a favor and build a new engine so you can put the stock setup back in before you have it smoged. I know that sounds crazy, but once you get an inspection that indicates non-Carb approved modifications, you can be in smog jail, until you prove you’ve restored the car to the stock setup. Just an idea. Good luck.

gkomo · Feb 4, 2026

Like others have said I wouldn’t be worried about out the block itself. Just paint it black and say you put some lipstick on the stock engine (if they even notice/ask).

s_vargas54 · Feb 4, 2026

Thank you everyone for the help! I appreciate the feedback. What are the thoughts on whether I need to stroke it to get where I want?? Not sure what I would be looking at with a new block, AFR or TFS heads, Holly Systemax, and a good cam. The forced induction is going to go on too. I want a good combo of motor and FI.

DadLife0724 · Feb 5, 2026

Not to on anyone's home turf, but Cali seems to suck for anyone who has any kind of hobby. Seems like a stressful place to live. And on top of that, EVERYTHING gives you cancer. Good luck with your block selection man. Hopefully you can get what you want done without extra bureaucratic bs.

AeroCoupe · Feb 5, 2026

So why not just get the Ford block and move on down the road?

https://www.ford.com/product/boss-302-engine-b-p2807016673?gmcid=marketplace-gs-cta-accessories&searchid=20643481100%7C157311292289%7Cpla-293946777986&fcid=pse_20643481100_google-pla&ef_id=EAIaIQobChMIoNS6zrHCkgMVOB-tBh2yyCIJEAQYASABEgLep_D_BwE%3AG%3As&s_kwcid=AL!2519!3!676763613569!!!g!293946777986!!20643481100!157311292289&gad_source=1&gad_campaignid=20643481100&gclid=EAIaIQobChMIoNS6zrHCkgMVOB-tBh2yyCIJEAQYASABEgLep_D_BwE

Ford no longer makes the stock block so I would think the state ref would have to accept it as a factory replacement being Ford sells it but you live it libtardville and they hate gasoline powered vehicles.

Noobz347 · Feb 5, 2026

I just have to wonder....

Even the members of this forum: How many people could pop the hood on a Fox, and determine with certainty that the block itself is factory or Memorex without pulling parts.

DadLife0724 · Feb 5, 2026

Not this guy, and probly not the goofballs doing smog inspections to stop the ice from melting.

Noobz347 · Feb 5, 2026

DadLife0724 said:
Not this guy, and probly not the goofballs doing smog inspections to stop the ice from melting.

That was my experience with them. Maybe they're smarter now?

gkomo · Feb 5, 2026

It does suck, lol. Besides a money grab by the State, i'm genuinely curious as to why anything else matters except for what comes out of the tailpipe. If it passes some required (and reasonable) threshold, what does anything upstream of the tailpipe matter? Being a Cali resident, i can at least understand the want for clean tailpipe emissions and no venting stuff to atmosphere. Otherwise, let it be what it is.

That Boss block is nice. Whats the power limits to that one?

AeroCoupe · Feb 5, 2026

Lots of folks making 800-1000 hp and some making more here and there. I would say keeping one together at that hp level is good parts, good machining, and a good tune.

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now i can hopefully expect to receive the shaft

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