Lets do this. Can you break down every difference between these two pr4 heads besides the valve train and stamp/casting marks? Thanks in advance.

pr4-5 off my '93 b18a1


pr4-1 off my '94 b18b

 

there arent any... almost 100% sure the pr4's are all going to be the same.

 

The PR4-5 is obviously looking better, but aside from that. On the left hand side of it, it has 4 markings. It might mean something??? Especially since somebody thing the PR4-1's markings should be different! It probably is nothing tho...

Here's what I found anyways...

Basically the PR4 is just saying what type of engine it's for,
the -1...-5 are the series for those types of heads
so far you should be able to just swap them and use what you like.

Deciphering the numbers on a Honda Head...
http://www.honda-tech.com/zerothread?id=721248

 

I believe they are identical. There might be minor cam changes, but I'm not sure...I haven't seen any numbers to state that they are different.

 

i believe those four markings you are talking about are a date stamp.

 

Can anyone confirm if the intake and exhaust ports are different sizes between pr4 series/years. If anyone with any ls head just laying around can measure the inner diameter vertically and horizontally that would be dope. My digital measuring tool is broken.

 

The castings are the same for sure.