SAMPSON&DELILAH Posted June 10, 2008 Report Share Posted June 10, 2008 How far do you take the porting on the turbine side. I know of a few on the boards that have done this, but I could not see how far it was taken for best performance. Also how much of a difference would you guys say it was. Ive ported the stock manifold as far as I could take it hoping to keep from bottlenecking at higher boost levels. I would like to hog the head being that it's so restrictive any advice would be appreciated. Fresh rebuild 3inch ex., Gm maft, 18g, 284h cam, 118 octane gas, ahps, can't remember everything. I want this thing to breath up top. Thanks Link to comment Share on other sites More sharing options...
Technology Posted June 10, 2008 Report Share Posted June 10, 2008 you can go down to 100 octane for assurance against knock. that super high stuff (c16 or c18 or whatever) has no place in our low compression, non-race engines. that 18g could never hope to pump enough volume to warrant such high octane. Meow. You need to make the turbine housing inlet the same size as the manifold hole. then at the turbine outlet, start inside before the wastegate hole re-enters and make a cone shape that gets larger and larger (still smooth though) until the rearward edge of the housing that joins the downpipe. Also, smooth and round the edges where the wastegate flow rejoins. reducing the size of "ledges" going in and out is what you want. You asked about how far in to go. Just make the transition smooth because no matter how nice you make that with a grinder, it's still got to cram into a much smaller space just a few centimeters away. Better off spending time on the housing after the turbine wheel. Link to comment Share on other sites More sharing options...
SAMPSON&DELILAH Posted June 10, 2008 Author Report Share Posted June 10, 2008 I run no boost retard and increased timing so I run high octane gas, sure down low it's wasted out the tailpipe , but when I really pound on it I like to have that safety net. I wasn't sure if the whole turbine housing needed to be equal in diameter thanks. Any before and after links. Phinko and Lizzord 30 did this some time ago but I could not find it. Link to comment Share on other sites More sharing options...
Technology Posted June 10, 2008 Report Share Posted June 10, 2008 I don't have any before/after pics, nor do I know where any are more than you, but I did do this to my 12a, maybe not as extreme as I said you should do, but I should have taken out more on the outlet side. I believe it did help, but of course, I didn't dyno or 1/4 mile it before/after. Link to comment Share on other sites More sharing options...
SAMPSON&DELILAH Posted June 10, 2008 Author Report Share Posted June 10, 2008 Thanks, any info is appreciated. Link to comment Share on other sites More sharing options...
Shelby Posted June 12, 2008 Report Share Posted June 12, 2008 i never thought to take pics untill the flaper cover was back on so it don't show the flaper hole but what little i did to this houseing made nite to day diff in my 20g the main idea is to open up the houseing just ahead of the flapper port,, lots of metal to remove,, the flaper now has aprox 1mm sealing lip but the area of flow to it is greatly increase'd it's just hard to see in the pics idealy you can send the houseing to mid west and have them install a 33mm flaper,,that'd realy open up the waste gate flow volume , along with your porting the rest http://starquest.i-x.net/album_cat.php?cat...SC&start=60 Link to comment Share on other sites More sharing options...
mstieg Posted June 12, 2008 Report Share Posted June 12, 2008 Take a look at the porting done to my 16g shown in my Signature Gallery. It's sold now, but had some hella porting done to both sides. Not sure how much this contributed along with the other mods, but it was spooling full 15psi by 2300rpms. Link to comment Share on other sites More sharing options...
SAMPSON&DELILAH Posted June 13, 2008 Author Report Share Posted June 13, 2008 Thanks guys, for a minute thought I was SOL on responses. Pictures are perfect . Also how would you rate this mod as far performance enhancement. I don't know alot about this mod so I'm going to get every bit of info I can. Link to comment Share on other sites More sharing options...
Shelby Posted June 19, 2008 Report Share Posted June 19, 2008 what some miss is it's the wastegate and flaper area that needs the porting the most,,once the turbo has reach'd the preset boost level ALL aditional exh gases need to go out the waste gate flaper port , this means you need to increase the amount of exh flow that the wastegate port is capable of flowing to gain upper rpm power increase with out increaseing the boost level Link to comment Share on other sites More sharing options...
mstieg Posted June 30, 2008 Report Share Posted June 30, 2008 what some miss is it's the wastegate and flaper area that needs the porting the most,,once the turbo has reach'd the preset boost level ALL aditional exh gases need to go out the waste gate flaper port , this means you need to increase the amount of exh flow that the wastegate port is capable of flowing to gain upper rpm power increase with out increasing the boost level bingo. This is why I had the turbine housing of my new turbo ported out last week. Hopefully the 38mm WG is big enough. The 16g pics of mine show some pretty hefty porting around that curve of that previous turbo. Sorry there's no 'before' pic for comparison, but compare my pics to any stock turbine housing and there you go. Link to comment Share on other sites More sharing options...
Shelby Posted July 12, 2008 Report Share Posted July 12, 2008 with a 38mm flapper you should be safe with at least 36mm opening and that will be near 70 to 80 % increase in flow thru the port over stock i'd love to see pics of the install of that 38mm flaper , 33mm was the largest i had heard of any one doing to the mits exh houseing Link to comment Share on other sites More sharing options...
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