I was just wondering if large ported heads really would make a difference when youre forcing in tons of air anyway. I was wondering if i could get away with a mild port, 1.6's and a decent cam and still make some sick power with some high boost.

 

Can you make big power with stock heads? Yes. But, you can make bigger power with big heads.

 

Yeh, the boost just increases the volumetric efficiency. So the more power you make NA the more you make Supercharged. The other consideration is low end torque. I went with a mild port to preserve the low end torque lt1's are known for. Mine is a street car though.

 

If you're going with heads, get some bigger CC volume heads to lower your compression.

If you port your existing heads, you'll see a PSI decrease, but a power increase, which is good because there's less chance of detonation with lower boost.

Mike

 

well im getting an all forged 355 or 383, so i will just have it built for my desired compression ratio. I was just wondering if i needed to drop another 1500 on heads right now if i didnt need them

 

I wouldn't worry about it if you're building a motor. Just turn up the boost if you get bored


Mike

 

I think you are mistaken... The boost pressure lowers IN THE INTAKE because the heads were a flow restriction. This means more air in the cylinders, which equates to higher cylinder pressures, and more chance for detonation.

 

You can get your porter to open up the bowls on lt1 heads so it lowers your compression. Just let them know what your application will be. You definately want to keep resurfacing to a minimum. I can't see spending $2000 for the AFR's. The blank trickflows are pretty reasonably priced and have bigger cc's.

 

If money is a little tight toward the end of you build then get the cambers cleaned up and if any money is left over ask them to do a mild port job on the exhaust ports. The stock heads have a poor intake/exhaust ratio for Forced Induction. I think its 68% or so, 80% is optimum.

My heads were done this way on a tight budget, I had enough left to do a 3 angle valve job which is the next step in pay as you go hot rodding.

Also, if you dont have an intercooler yet get one before spending money on heads.

 

Of course the heat generated through lack of efficiency will aid in detonation, but "more power at less boost" isn't quite like getting a free lunch. You will certainly have more pressure in the combustion chamber.

In making the previous post, I did infer that Kraest's statement meant that you could up the pulleys back to the same boost level and still be safe. My bad... With the same size pulleys, you should be fine with a little tweaking of the timing and fuel tables. If it's a stock shortblock, I wouldn't go upping the boost back to what it was before the heads were done.

 

PSI dont make power so much as CFM...

take poorly flowing heads and put 6 psi to them...

now take the same motor a nd put realy good heads on and 4 psi will make the same power and not be nearly as hard on the motor... heads area big deal.

 

as i understand it, heads aren't the most important part to FI, but once you get up there in horsepower they will become a resitricion in your system. to begin wiht though i'd focus on getting a good FI setup first.