newbvetteguy

I got my FIRST Fuel Injection intake from Ken all beautifully gasket matched and smooth ported at the exit to a FelPro 1206 and now shiny Thermal Barrier Coated (to make it shiny and maintenance free more than anything: I'm vain).


My question is about the EGR Bump that starts at the throttle body exit and then continues down the center bottom of the plenum: Does this possibly do anything GOOD for me like potentially improving the airflow to the FIRST set of runners (one of the two sets of runners that flow less than the others)?

My natural inclination is to grind away the EGR bump at the end of the throttle body and at the beginning of the plenum to smooth the airflow and reduce this air restriction.


I asked Ken about it over email briefly and what he would say was that the FIRST engineers knew what they were doing and his stance is to not mess with the intake or you could make things worse. -I had already ground away half it it and I'm just pausing to consider whether I should stop where I am and gasket match it and then match the other side to what I've already done, or get rid of this stupid thing and it's airflow restriction.


Forgot the FFS tag so here it is: FFS "First Fuel Injection" TPI Long-runner SBC

Adam
plenum side EGR bump-notice EGR passageway is solid in this newer casting



bad photo but you can see the EGR bump at the back

newbvetteguy

Update: I decided to kill the bump. I like it better that way.

Adam

BluFBdy

iTrader: (1)

And here I thought I was getting crazy with gasket matching mine lol I decided to leave things be beyond my minor cleaning up of the throttle body and the matching job, been sitting on this intake for 3 years now finally getting around to getting it on the engine

newbvetteguy

Ken @ FIRST put mine on the CNC to get it up to a 1206 and then, due to a slight delay in getting mine to me smoothed the transitions all out and gave it a real nice port job so it would be perfectly gasket matched- the Profiler 195cc heads are PERFECTLY gasket matched out-of-box to a 1206 Felpro.


I smoothed the transition into the throttle body, and runner #1, the back of the plenum towards the crappier flowing cylinder #7 and smoothed and opened up the transition into cylinder #7, too.



-I go kinda OCD...

I cleaned up all sharp spots and exposed spark plugs in my heads, "water tested" the chambers/valves with rubbing alcohol, cleaned up the spark plug holes, polished the exhaust ports, measured the installed height of all spring pockets in both heads and even researched the best atomizing, lowest response time fuel injectors for my combo (Bosch IV with adapters).


I also tried to figure out which particular model GM LS ignition coils offered the best perf for the buck.

(I waste a lot of time on stuff that probably doesn't matter much/at all, but it's my only build ever so I'm happy to spend my time doing it the way I want; plus I don't really know what I'm doing so I really need to think everything through really slowly first.)

--If I had the tools to do it, I would remove the old EGR "box" in the back of the plenum that's just there from the legacy casting that used to actually have EGR passages, but I don't and I need to keep moving forward...



Adam

newbvetteguy

I was considering leaving the hard "step" in the intake from the CNC machine opening it up to Felpro 1206 to do a super simple gasket match because my cam's got 51 degrees of overlap and I heard that such steps can act as anti-reversion dam, but Ken volunteered to smooth port it and it looks gorgeous so I wasn't going to complain!


-I've got OCD enough on this build, I secretly lament not knowing about doing a firing order swap to help out the already challenged cylinder #7 from having cylinder #5 fighting with it even though I realize it's probably worth low single digit HP....



Adam