I am thinking of either putting 18* heads or sb2.2 heads on my LT1 block.

I heard that I can still use the same valvetrain components on the 18* heads that the LT1 heads use unlike the sb2.2. Is this true? If so I think I would want to go with the 18* heads, right? Cause wouldn't it be cheaper and alot less of a headache to do?

Also what intake would I go with if I use the 18* heads and is there any intakes that have fuel injectors for each cylinder?

Also how would I make these 18* heads street legal emission wise? Does going high in the rpm's some how make them illegal if I use a small 350? If so why? How big would I need to go cubic inch wise and would this help make the heads legal by not having to go super high in the rpm's?

Would I need a different pcm and if I do use a different pcm would that be legal?

Thanks for any help you can give.

 

Define what you mean by "street legal emission wise". To be 100% compliant, you can't swap on new heads, a new cam, or a new PCM unless its got a CARB-EO emissions exemption number on it. You aren't going to find any 18deg or SB2.2 heads, or an aftermarket PCM with those certifications.

If you mean can it be tuned to pass a rolling tailpipe emissions test, the answer would be "yes", but you might end up using a cam so mild that it wouldn't justify a set of 18deg or SB2.2 heads.

The fact that an engine turns high RPM does not make it "illegal", unless to achieve that you've changed some major component that does not have CARB-EO approval.

 

Not trying to rain on your parade, but it sounds like you're thinking too big. If you have to work around emissions then you're better off sticking to the popular aftermarket stuff, because most of it has been tried and tested on other cars, you'll be less likely to have problems and more likely to tune things better.

I'm all for trying unique projects for some crazy horsepower gains, but on the surface here it sounds like your plan is going to give you more headaches that it will be worth.

 

if you drive this car on the street then the 18* and sb2 heads are just a waste of your time researching

These are race parts and very very expensive, not to mention a bottom end etc.

like the other 2 post I think your better off lookin at carb appoved items and good tuning

 

I guess what I mean is would it past the sniffer test or would I need a bigger engine to help it? Cause I thought if you had a bigger engine you don't need such a big cam.

Same thing if I decide to use a turbo. I also would not need such a radical cam, correct? Not sure if I want to use a turbo but if that would help me pass the sniffer test with the 18* heads than I'll save some more money?

Also I would not have to have near as much boost to get that much horsepower with the 18* heads like I would on the LT1 heads, right?

 

A turbo and sb2 heads on a LT1? 40-50k?

 

Well I'd rather do the 18* degree heads cause I heard something about I can use the same valvetrain components like the LT1 heads or something like that. I heard going this route was cheaper than sb2 heads. Would 18* heads with a turbo cost that much?

 

Yes and no. The only 18 degree heads I know of that you can use your 23 degree parts on are the brodix 18X std head. this head will still require flycut pistons at a minimum (18 degree heads are your best bet)and a 18 degree intake converted to EFI. You can use your existing rockers and exhaust, but need custom length pushrods. Let's not mention hood clearance...

There are now 23 degree heads out there that flow in the same ballpark as some of the 18's. I'm going with a 23 degree head on my new motor though I considered the 18 degree and sb2.2

sb2.2 flows like MAD, but would require cubes or RPM to take out the low RPM sluggishness you'll feel compared to stock. And your rev limit is only 7200. On a 350 or even a 383, that's leaving alot on the table. If I build a motor larger than a 434, It'll be a 454, with sb2.2's on it. Ported 18 degree heads on a motor that large would be a good street combo. But I havent seen any 18 degree intakes that are EFI ready, no.

The brodix 18X STD is the closest thing you're gonna find, and even without porting, will cost you $4500 by the time you complete the package, easy. I'd stick with a converted allpro similar 23 degree head. That's the reason I am... because I can get a set of 230cc 23 degree heads ported out to outflow alot of 18's out of the box, and have better flow velocity and decent torque compared to larger more exotic heads. I'm gonna spend probably $3500 on my top end and that includes a ported single plane, heads, porting and a cam. The rest of what is left will go into shaft mounts.

 

Somehow, mentioning 18-degree heads and emissions in the same sentence seems like the ultimate oxymoron.

BIG heads are not intended for street cars that have to pass emissions. They typically have huge ports, and the low port velocity at low RPM is going to kill low end, and push out lots of emissions. They are intended for max effort track setups. Yes, it would be fun to try and drive them on the street - and some people have - but to do that AND have some hope of passing emissions indicates you might not quite comprehend the implications of the engine you are hoping to build.

What is your HP goal? How will the car be used - daily driver, weekend warrior, show??? What is the ultimate configuration.... no "turbo" was mentioned in the original question???

And you never answered the question..... I'll rephrase it.... what emissions do you have to meet?

 

DITTO

Fred hit this one on the nose.

BTW did anyone else wonder why he's asking this with a CC306 and emissions now?

Bret

 

I'm not sure if that was a ******** remark or not. I already know my 306 cam won't pass but the county I live in only eye's the test. They don't use the sniffer. But I might one day move to a different county and I will most likely see the sniffer. So I do one day plan on rebuilding another engine cause I enjoyed the first rebuild. But if you don't think I could pass I will just put a turbo on some 23* heads and hopefully I can get 600-650rwhp on pump gas and still pass emissions. That is my goal anyways.

 

i don't think he was trying to be a ********...you just ask something that I really don't think you understand

You need to do alot more research....find someone that has the power or similar combo you want and do some more research

The sb2 and 18* stuff is not made to ride around on the street

 

Not unless you have a lot of coin.

Ok so don't worry about emissions if they don't sniffer test it.

The 18X heads are ok, but there are 23° stuff out there that is better.

Bret

 

i went w/ 23* stuff as i already had a 23.deg bottom end.. I.e Piston's for it.. If i had the chance to do it over again i'd probably go 15* GM casting's or somthing.. It's very pricey to go into the upper echelon of 23* stuff.. and no stock/factory valve trains are compatible, offset rocker's, lifter's,etc are required for any of the better 23 deg. heads.. But again like most have mentioned emission's/and High HP LTx's are not compatible.. Good luck on your quest though..

 

600-650rwhp can be accomplished on factory 23 degre LT1 ported heads and a small cam (215-20 duration) with a small turbo (T70-T76 turbo). No need for exotic stuff.