DIY Head Porting Project (5.3 Heads) Lots-O-Pics 56k Beware by Mikey 97Z M6

7 minute read

DIY Head Porting Project (5.3 Heads) Lots-O-Pics 56k Beware 

Compliments of Mikey 97Z M6 @ https://ls1tech.com

12-16-2006

I thought you guys might like to see some progress pics of my DIY head porting I started a couple weeks ago. I think I took the intake runner too large, as the low lift numbers look a bit soft. I'd appreciate some pointers/tips from those that have done this before with good success. This is my first set of LSx heads, but I'm not new to head porting. I've ported many sets of LT1 heads in the past, getting high 260's, to mid 270's out of them.

Had these 5.3's flowed with the stock, super-tiny 1.89/1.55 valves before I started the porting. The guy that flowed them wants to learn more about the LSx stuff, so he has offered to flow test them for me for FREE if I share my porting techniques with him. It's a great deal for me considering he normally charges $60/chamber, per flow test. I was shooting for numbers in the mid 290 range for the intake, and around 220ish for exhaust, both at .500-.550 lift range.

I took many photo's of the progress and I'm still finishing up the rest of the ports. Here are some flow numbers of the stockers with the tiny 1.89/1.55 valves. The intake became turbulent at around .400 lift according to Dennis, the guy that flowed them

Here are the stock flow #'s @ 28":

lift........./ int../ exh
.200...... 136.... 105
.250...... 167.... 121
.300...... 192.... 137
.350...... 211.... 155
.400...... 223.... 171<-- became turbulent on intake side
.450...... 223.... 190
.500...... 224.... 203
.550...... 228.... 213
.600...... 233.... 217
.650...... 237.... 218
.700...... 239.... 221


Here are the "after porting" flow numbers. Please note that the throat cut still needs to be blended into the bowl (it left a ridge), so I'm expecting around a 5cfm bump accross the entire range afterwards. I'm having this chamber re-tested next week, hopefully. As mentioned previously, I think I made the intake runner too large, so the low lift numbers are a bit on the soft side. I'm fairly pleased with the exhaust though, as these heads are planned for a nitrous engine.

lift........./ int../ exh
.200...... 131.... 111
.250...... 160.... 131
.300...... 190.... 149
.350...... 217.... 168
.400...... 240.... 183
.450...... 257.... 201
.500...... 273.... 217
.550...... 283.... 228
.600...... 289.... 235
.650...... 295.... 241
.700...... 298.... xxx



Here's some pics of the stockers as-is before port work:

Many more pics to follow........

Here's some "in progress" pics from porting:

Roughing in the intake entry. Sorry these turned out a bit dark.

Here I just did some rough shaping in the bowl area, blending the intake porting into the bowl and shaping the valve guide area.

Here's some pics after I completed all the shaping, then hit the entire port/bowl with a cartridge roll. I'm fairly pleased with how this one turned out. These LSx heads are a walk in the park compared to porting an LT1 head. I have about 2.25 hours into this port and it was my first one.

Here are the pics from porting on the exhaust and chamber.

Comparison between the stocker and the ported version.............

Shot of the chamber with both runners finished up.....

Shrouding of the valve before port work.....

After unshrouding the valve.......

Initially I had intended to use 2.00"/1.60", but after Dennis roughed in the valve seats, he didn't like the shrouding of the 1.60" exhaust valve. He's going to cut the Manley exhaust valve down to a 1.55", and that is the numbers you see after the port work. I'll have to ask him what seat angles he used, but there are no back cuts, or at least he didn't mention it to me when I picked up the head yesterday. 

Yes I agree, and I realized how big the intake port was after I had already started. I really didn't intend to go so crazy on the size, and that's probably hurting my low and mid-lift numbers. Well, that and the ridge left from the throat cut on the seat.

I didn't CC any of the ports because they are what they are lol... Nothing I can do to change them now. If I port another set, I'll try to keep the port size down, through the narrow part of the intake runner.

These were tested with 2.00"/1.55" valves, not 2.02".

As for the dyno testing, I don't have anything to compare with because I'm building this LS1 for my engine swap in my 97.