Dazaa Rafae Aman

As I delve deeper in to the world of c3's I've realised that the later chrome bumper models are a bit cheaper than the earlier ones, however these were hit by the emissions regulations of the 70's which lowered power. How difficult would it be to get the extra hp out of these smog regulated engines? Is it a case of swapping the carb/intake and headers or did they change the cam/compression ect?

Rescue Rogers

the factory HO cars had better cams and heads, some had intakes similar to the edebrock RPM but not all. You can really see it with the HP drop in the 70 to 71/72 LT1

I would start with cam and compresssion. Both of which were changed to have better emmissions. Stepping up to a really high flowing set of aluminum heads with a 64cc chamber will get you decent compression and a good cam will get it the air/fuel for the power. Those are the first 2 things to change for any power increase above headers and intakes.

then i would go intake and 2.5 inch exhaust. headers last. most gains with headers are WOT high RPM

7T1vette

Any small block Chevy engine can be modified to obtain 400+ hp with the right "goodies" in it which are complimentary. That last phrase means that the various parts selected for the upgrade work well with each other, so the benefit is maximized. Once you remove the pistons, crank, intake system, exhaust system, heads and cam...the 350 blocks are all basically the same. Yes, some have 4-bolt mains from the factory, but 2-bolt blocks can be upgraded to 4-bolt with some machine work.

So, have at it! All you need are TIME, MONEY, KNOWLEDGE, and/or a good engine builder.

If that doesn't answer your question, revise it and ask what you really want to know.

C3 Stroker

Yes, all of the above from the previous posters. Speed costs money, how fast do you want to go?........

Jason Staley

Agree with all the above, but also realize that the way HP was stated by the OEM's also changed around 1972. HP went from being stated as GROSS to NET, which also affects how powerful the car appears in the literature.

https://ateupwithmotor.com/terms-tec...et-horsepower/

449er

How to gain more power? that's easy....LS swap

Rescue Rogers

yes. the internals were the same 71 and 72, just the gross to net changed. I was just pointing out the big drop from 70 to 71 was the emmission( compression and cam change) the gross to net was insurance as I understand it

jackson

In the case of base L48 aka ZQ3, from '70 (300hp) to '71 (270hp) suffered gross hp loss about 10% ... but seems they both share 929 hft cam ... so seems what changed was only compression dropping from about 10.25:1 to about 8.5:1... nearly 2 points.

*you and yours have a happy & safe new year!

Kevova

Modern small chamber aluminum heads. Today's heads are much better than anything from the 70's. The compression needs to 10 to 1. Forced induction would be another option.