[Trav35thGT]

I found a good deal on some used Trickflow 44cc heads. My plan is to keep the car NA. My question is, should I hold out and find a set of used 38cc heads or just go with the 44’s. I know I will lose some compression going with the 44’s but how much hp could I be leaving on the table?

 

[eschaider]

In a normally aspirated application, small changes in compression ratio produce small changes in engine power output. If you search the internet, you will find all manner of representations, most all in conflict with each other. The most reliable information source for this question is probably Wallace Racing. Here is a link to their calculator. Click here=> C/R Power Effect. When you use it, you will discover the difference to be vanishingly small. Test it against OEM configurations where Detroit changed the c/r between years and you will get a pretty good agreement.

In high-powered race engine applications, it can provide a slight edge in performance. In everyday use, the power will be vanishingly different. You will pick up some low-end torque which will register on your seat of the pants dyno - that's about it.

 

[Trav35thGT]

Wow, i just checked that link out and was really surprised. I was expecting at least a little bigger difference between the different compression ratios but the results were only about 5 horsepower. If I would end up getting the 44cc heads then if I ever would want to get a blower or turbo I would still be safe going that route. Thanks for the response.

 

[Billy the average guy]

We just finished a rebuild on our 4.6 using an Trick Flow 44 MM and they work great. We had originally ordered 38 MM but the back order was well over a year. I personally feel you’ll get more benefit out investing in good cams.

 

[Blackmetal2088]

Nice build, will you be dynoing it when done?