Budget 12A SP build - Page 2

rxtasy3 · 01-09-2011, 09:57 PM

tim, the wear on the oil control rings look really good, can reuse. if u reuse all the seals and springs associated with the rotors, they all should remain with/be put back where they came from. good luck with ur first build and hope it turns out to be a good running/long lasting engine. i myself only have 2 builds(same engine) under my belt and hoping to do more in the near future. so far have bout 80k on the 2nd build.

t_g_farrell · 01-10-2011, 09:25 AM

Micheal thanks for the comment on the oil control rings. Unfortunatley I
didn't keep the parts sorted as to what rotor they belonged to because I
thought I wouldn't be able to use the original rotors

Now it
looks like the original, lighter rotors can be used. I'll just make sure
everything is within tolerances when I put it back or replace it. The hard
parts are all so new that none of them show any wear at all. Especially
when compared to the other engine I tore down which was beat to death.

I think I'm going to do the street port by porting the secondaries fairly
aggressively and leaving the primaries pretty much stock except for
smoothing the area near the edges of the port openings a bit for better
flow. I've been doing a lot of reading on nopistons which has been very
educational. I want to maintian as much of my low end as I can but get
a good bump in hp once I hit the higher rev ranges. The exhaust ports
haven't decided on yet but I'm still reading.

Heres one question on the exhaust porting. Do you port the inserts at all or
just get close the edges of the end of the insert and shape it out from there?

NoDOHC · 01-10-2011, 07:28 PM

I usually pound them up as much as possible with a punch and hammer (until they are tight against the housing) and then polish them to 600 grit or so (minimizes radiative heat transfer from exhaust gasses, improves flow, makes slightly louder).

Constantly increasing cross-section is your friend for the exhaust.

For the intake, don't bring the port up any more than you absolutely have to if you intend to keep some semblence of low end. Raising the far edge (furthest from the housing) gives much greater performance improvements than raising the near edge and you can raise the far edge quite a bit without changing the port timing.

t_g_farrell · 01-27-2011, 01:22 PM

So are you saying for the exhaust you want a megaphone or cone shape with
no bump or waist in the middle? In other words you don't want anything thats
like a venturi on the exhaust.

It looks to me like if you follow the angle and contours of the stock insert
and carry that onto the housing as you port you end up with the classic
D shaped exhaust port. Good idea ?

01-09-2011, 09:57 PM	#16
rxtasy3 rotary madness Join Date: Apr 2010 Location: spartanburg, sc Posts: 78 Rep Power: 16	tim, the wear on the oil control rings look really good, can reuse. if u reuse all the seals and springs associated with the rotors, they all should remain with/be put back where they came from. good luck with ur first build and hope it turns out to be a good running/long lasting engine. i myself only have 2 builds(same engine) under my belt and hoping to do more in the near future. so far have bout 80k on the 2nd build. Last edited by rxtasy3; 01-09-2011 at 10:01 PM.

01-10-2011, 09:25 AM	#17
t_g_farrell Waffles - hmmm good Join Date: Aug 2008 Location: Huntersville, NC Posts: 757 Rep Power: 0	Micheal thanks for the comment on the oil control rings. Unfortunatley I didn't keep the parts sorted as to what rotor they belonged to because I thought I wouldn't be able to use the original rotors Now it looks like the original, lighter rotors can be used. I'll just make sure everything is within tolerances when I put it back or replace it. The hard parts are all so new that none of them show any wear at all. Especially when compared to the other engine I tore down which was beat to death. I think I'm going to do the street port by porting the secondaries fairly aggressively and leaving the primaries pretty much stock except for smoothing the area near the edges of the port openings a bit for better flow. I've been doing a lot of reading on nopistons which has been very educational. I want to maintian as much of my low end as I can but get a good bump in hp once I hit the higher rev ranges. The exhaust ports haven't decided on yet but I'm still reading. Heres one question on the exhaust porting. Do you port the inserts at all or just get close the edges of the end of the insert and shape it out from there? __________________ 1980 GS stockport, Fat Nikki, RB Dual Facetfuel pumps, Holley regulator, RB Street port exhaust, 2GDFIS, MR2 MK I electric fans, 2G strut bar, relayed fans, lights and fuel pump, LEDs Project Fat Nikki Budget 12A rebuild Video setup < $30.00

01-10-2011, 07:28 PM	#18
NoDOHC The quest for more torque Join Date: Sep 2008 Location: Sheboygan, Wisconsin Posts: 855 Rep Power: 17	I usually pound them up as much as possible with a punch and hammer (until they are tight against the housing) and then polish them to 600 grit or so (minimizes radiative heat transfer from exhaust gasses, improves flow, makes slightly louder). Constantly increasing cross-section is your friend for the exhaust. For the intake, don't bring the port up any more than you absolutely have to if you intend to keep some semblence of low end. Raising the far edge (furthest from the housing) gives much greater performance improvements than raising the near edge and you can raise the far edge quite a bit without changing the port timing. __________________ 1986 GXL ('87 4-port NA - Haltech E8, LS2 Coils. Defined Autoworks Headers, Dual 2.5" Exhaust (Dual Superflow, dBX mufflers) 1991 Coupe (KYB AGX Shocks, Eibach lowering springs, RB exhaust, Stock and Automatic)

01-27-2011, 01:22 PM	#19
t_g_farrell Waffles - hmmm good Join Date: Aug 2008 Location: Huntersville, NC Posts: 757 Rep Power: 0	So are you saying for the exhaust you want a megaphone or cone shape with no bump or waist in the middle? In other words you don't want anything thats like a venturi on the exhaust. It looks to me like if you follow the angle and contours of the stock insert and carry that onto the housing as you port you end up with the classic D shaped exhaust port. Good idea ? __________________ 1980 GS stockport, Fat Nikki, RB Dual Facetfuel pumps, Holley regulator, RB Street port exhaust, 2GDFIS, MR2 MK I electric fans, 2G strut bar, relayed fans, lights and fuel pump, LEDs Project Fat Nikki Budget 12A rebuild Video setup < $30.00