Mod response
 

What part of an engine determines how responsive cars are to mods. Like why do little engines like turbos, or why huge LS/LT1's take to cams and spray so well. Why arent the 3.8 and 4.6 engines as responsive.

RE: Mod response
 

It's not a case of "responsiveness" nor a single "part of an engine"; it's the inherent design characteristics of an engine that make or break it. The LS1 was designed with heads designed to flow better than anything GM had previously designed. I think the engineers at GM would have put in a bigger cam(that would have made much more power) if it would have been emmisions compliant and\or still maintained bottom end torque(remember; they are for sale to the masses & not specifically to drag racers). I don't know where your comming from on the 4.6's; the 4.6 mod motors respond fantastically to forced induction if you have the P.I. heads that I believe were used from 99-up.
The earlier 4.6 heads wern't designed very well; it's as simple as that. All engine's are basically air pumps. The more air, the more fuel, the more power. Of course the smaller engines get nowhere near the "tech" in thier developement since the engineers whom designed them wern't told to make 'em "hipo'. Most likely, the engineers were instructed to "Make it small, get good gas mileage, cheaper to make, etc" .....IMHO

RE: Mod response
 

So bigger engines should take to bolt on mods and cams better

RE: Mod response
 

No not really, it's just that a bigger engine has the potental to move more air, but big engines also respond well to FI. As the poster above said, you need to look at the engine as a whole system, but heads are really the part that can make the biggest differance.

RE: Mod response
 

So the design of the heads is what determines how well the engine takes to mods

RE: Mod response
 

There is no single component that determines if a motor will take well to mod's or not. You have to look at the total combination of parts from intake to exhaust, determine what the weaknesses are, & address them accordingly. Don't get me wrong; good heads are a solid foundation upon which to build a motor. But, if the intake is restrictive, the fuel delivery system is too small, the throttlebody is small, cam profile is too small, etc; then all those areas have to be improved to fully see the potential of the stock heads & motor.

RE: Mod response
 

Whoops.... double post....Sorry.....