Steel IH Gaskets & Primary Port is 38mm

[KILLSHOTS]

Originally Posted by KJL

Finished reassembly and it starts and runs great. No more leak either. That said, while i had it apart i removed the alternator and had it checked out because I had some battery issues and NAPA said it was good. Not good. Lights pulsate just a tiny bit. Most noticeable at idle. Unplug alternator and pulsating stops...bad voltage reg.... great. Looks like another plenum removal exercise, i don't understand how this could have passed... The guy checking it didn't seem like he know was he was doing.... should have taken it elsewhere. I haven't put Marcs chip in yet, need to get the car registered and through ridiculous emissions test. I need to get some miles on the car before I bring it. Feel like I am talking to myslf here but I can't stand it when threads are started but not really completed. After I get the car registered and the new chip installed, I am going to dyno the car with both chips and see if all the porting work and Marc's chip provided any additional HP.

Marc suggests to run the car through emissions with the stock chip, if possible. Also, make sure you run the test with the power key OFF or you will not like the result. When I had my 15K mile Z with brand new injectors and plugs tested, I didn't know that...ran it in full power mode and it failed MISERABLY! (BTW, the car was 100% stock at that time, except for those new injectors)

[KJL]

Thanks, that is a relief! The three attach pictures show the battery relocation, intake temp sensor relocation and a nice clean under plenum area.

[KJL]

The dyno numbers are in. Brief overview, discovered leak between injector housing and head. Removed intake and injector housing and discovered what appeared to be an aluminum gasket. Also discovered a mismatch between the injector housing ports and heads. Using a die grinder, I matched the ports to the heads, replaced gasket with one that actually seals and replaced the performance chip that was installed with the car when I purchased with a Haibeck chip.

The numbers from an older dyno run from previous owner:

Max rwhp: 392 Max rwtq: 357

Yesterday's runs:






Basically no gains from the extra port work matching the injector housings to the heads. The car is also running a bit lean. Marc is going to adjust the chip for me which should be good for a couple of extra ponies.

[KJL]

I hope someone finds this thread helpful. The dyno chart below represents the last run after Marc adjusted the a/f ratio numbers on my chip. The only performance mods on this engine are port work to injector housing, port matched heads to injector housing (While on car), intake and throttle body, headers, high flow cats and injectors. Also removed the typical emissions stuff and coolant bypass. I still have the secondary throttle blades in place and functional. Also relocated the battery and swapped to a light weight Odyssey AGM battery and relocated the intake air temp sensor to in front of radiator. The car passes GA emissions. It would be interesting to see if the blades could be forced open if the car would pass. If so, I would remove all that crap as well.

[phrogs]

Well I also find that they leak even when you use the right gaskets, Torque them correctly and it still leaks, every LT5 I have had leaked around the IH and I just learned to deal with it.

Mine were all 1990's as well.

[KJL]

Originally Posted by phrogs

Well I also find that they leak even when you use the right gaskets, Torque them correctly and it still leaks, every LT5 I have had leaked around the IH and I just learned to deal with it.

Mine were all 1990's as well.

This was beyond just a leak, the valleys that exist just below the injector housings would fill with PCV oily liquid. The metal gaskets were far from sealing. Tight as a drum....for now.

[Harvie]

Try using Permatex 3H item 80019, it will seal the gasket.

[Hog]

Originally Posted by KJL

The dyno numbers are in. Brief overview, discovered leak between injector housing and head. Removed intake and injector housing and discovered what appeared to be an aluminum gasket. Also discovered a mismatch between the injector housing ports and heads. Using a die grinder, I matched the ports to the heads, replaced gasket with one that actually seals and replaced the performance chip that was installed with the car when I purchased with a Haibeck chip.

The numbers from an older dyno run from previous owner:

Max rwhp: 392 Max rwtq: 357

Yesterday's runs:






Basically no gains from the extra port work matching the injector housings to the heads. The car is also running a bit lean. Marc is going to adjust the chip for me which should be good for a couple of extra ponies.

Unfortunately typical results from gasket matching/port matching. Most flow occurs in the middle of a port, not along the sides.

I used to port/gasket match all my junk, and your dyno results prove why I shouldnt anymore.

thanks for sharing, you have a strong running engine there, guessing approx 480hp at the crank. Cheers!

[Harvie]

Bigger/larger is not always better, higher rate of flow is what is needed to make more power.

I have ruined 5K heads opening them up to where they had to be welded back up to have the material restored then the ports recountoured to get the propper rate of flow.

The use of a flow bench is the best way to accomplish it. The cheapest way (in the long run) is to pay a expirenced person with a flow bench do it and you clean up/polish after them.

To increase overall air flow you have to do all the passage ways both into the engine and back out of the engine. to maximize the flow and pattern. Opening up just the middle actualy reduces the flow and creates bubble/bottle necks that lose power.

I have cleaned up behind the very best Batton Superflow Mondello Brad Anderson Ladds Sonny Barton etc all have the same charastics, maniflods, headders, exhaust that flow the air in a uniform manner thru simular size openings with minimal redirection/obstruction of the air patterens. That is how more power is created. The Air pump that flow more air makes more power...

[KJL]

Originally Posted by Harvie

Bigger/larger is not always better, higher rate of flow is what is needed to make more power.

I have ruined 5K heads opening them up to where they had to be welded back up to have the material restored then the ports recountoured to get the propper rate of flow.

The use of a flow bench is the best way to accomplish it. The cheapest way (in the long run) is to pay a expirenced person with a flow bench do it and you clean up/polish after them.

To increase overall air flow you have to do all the passage ways both into the engine and back out of the engine. to maximize the flow and pattern. Opening up just the middle actualy reduces the flow and creates bubble/bottle necks that lose power.

I have cleaned up behind the very best Batton Superflow Mondello Brad Anderson Ladds Sonny Barton etc all have the same charastics, maniflods, headders, exhaust that flow the air in a uniform manner thru simular size openings with minimal redirection/obstruction of the air patterens. That is how more power is created. The Air pump that flow more air makes more power...

A little late on this reply, to your comment regarding just opening up the middle, The car has headers with high flow cats through high flow mufflers, the injector housings, intake plenum, throttle body were all professionally "significantly" ported, previous pics earlier in post show this. This is the main reason why I decided to do it. It made no sense to open up every passage in the system but then restrict it at the head. I contoured the openings based on advice from forum members and articles. If there was only a mild mismatch, I would have left the head alone but it was significant. Port/gasket matching is not rocket science.....that said, I would never consider attempting anything other than port/gasket matching. My guess is it did help the flow and that is why she was running a bit lean, after Marks adjustment, I picked up a few more HP. I could safely say the port matching likely gained about 5 HP.....was it worth it? I love working on cars, if I didn't do it, I would always be wondering.