"Igor had a car and a gallon of rum. We met in front of Baldy's house.
Igor passed the bottle. Good stuff, it really burned the membranes of
the throat. Igor drove his car like a tank, right through stop signals."
- Charles Bukowski - Ham on Rye
Photo by Bubba
Z.
 Here is an interesting comparison, an SR20VE throttle body next to the SR16VE N1 spec throttle body (SR20 is on the left). I might have experimented with a switch if I didn't go turbo. This could be a good potential hop-up for a NA SR20VE application. |
DE Head
Photo by L. Koloszyc
 VE Head
VE HeadPre-Porting
Post-Porting w/TBC
 VE Exhaust Ports
VE Intake PortsPre-Porting
Pre-Porting
 VE Exhaust Ports
VE Intake PortsPost-Porting
Post-Porting
Photo by L. Koloszyc
Photo by L. Koloszyc
DE Exhaust Ports
DE Intake Ports Photo by L. Koloszyc 
 Above is a series of shots showing Lee Koloszyc's DE head, my VE head and the intake and exhaust ports before and after mild porting. There are also some shots of the cams in and out of the head. Check the exhaust pattern on the exhaust port side of the VE head pic. This shot really illustrates the obvious header mismatch problem and the leakage. 
 VE Timing
DE TimingAbove are a couple valve timing diagrams - one from the DE and a set for the VE. You can see from the VE diagrams that I was not overly paranoid with my concern about reversion. I'm VERY conservative when it comes to failure-prone systems and a turbo added to this mix made me nervous. You can see that I went a little overboard with my conservatism in that I ordered upgraded brakes before I had any serious power in the car, negotiated TWO coatings packages to ward off detonation and other nasties and beefed up the transmission way before it was necessary. The cam overlap does not fall into the "overboard" category. I felt it was a serious threat to the project from the beginning. Without proper tuning, I could have ended up with at best an over-hyped and under-powered turbo motor or at worst one that was detonation plagued or blown. Clark Steppler rigged a switch to the VVL solenoids in order to find the optimal point in the RPM range to switch to the aggressive lobes. This was somewhat uncharted territory as info related to a T3T4/SR20VE combo is somewhat hard to come by. A number of points were tried in the 4000 to 6000 range and we were surprised to find that the original NA 6000RPM lobe switch worked best with the turbo and any switch lower in the RPM range resulted in loss of power. Swain Tech Package Piston Dome (Gold Coat) and Skirt (PC-9) Head, Valve Faces/Stems/Backsand Exhaust Ports (Thermal Barrier Coating) Valve Stems/Backs (Flow Coat) Intercooler (Black Body Emitter) This was by far the cheapest package. The prices for these coatings are quite reasonable. 
 Uncoated vs
Exhaust PortsPC9/Goldcoat Piston
Post TBC Valve Stems Post TBC/Flow Coat Above is a shot with the SR20VE piston next to the gold-coated/PC-9 treated forged piston and some shots of the VE head, intake ports and the valve stems (pre-micro-polishing) after the TBC and Flow Coat had been applied. In case you are considering coatings for a similar application... and are having the valve faces/combustion chamber covered with TBC and/or Flow Coat, make sure you remove (micro-polish) any coating where the valves contact the seats in order for proper seating to occur. Starting with the introduction of the Z32 in 8/89, Nissan began utilizing a Poly-Moly-like anti-scuffing-anti-friction tungsten-content coating (similar to PC-9) on the Z's piston skirts and it is still utilized in stock motors today. The latest Sentra incarnation and the new G20, with thier updated SR20DE, have the same coating on their slugs as does, of course, the Z32 which is still in production in Japan. PC-9 was applied to the piston skirts in order to reduce piston and cylinder wall friction and wear. I spoke to Dan & Rich at Swain Tech about Poly-Moly versus PC-9. Poly-Moly and PC-9 are both polymer matrix tungsten self-lubricating non-insulating coatings. PC-9 was developed for high load applications (turbo) and has a higher tungsten content with Poly-Moly being ideal for NA applications. The price difference is negligible. The Flow Coat, which is black in color, was applied to the back side of the intake valves where carbon buildup can occur. After shutoff, unused fuel settles and carbonizes on the back of the intake valve. Over long periods this buildup can affect performance. The flow coat creates a smooth surface that allows this minscule buildup to be sloughed off at each startup. The properties of Gold Coat and TBC have been addressed by Mike Kojima, so I won't rehash them here. The Black Body Emitter (BBE) coating helps dissipate heat from surfaces of parts that are charged with the cooling of gases or liquids, such as the intercooler while contributing to the stealth of the vehicle. While I was on the phone with Dan grilling him about the BBE, he mentioned that he received radiators from two IRL teams that day that were to have BBE applied. I considered having BBE applied to the new radiator but thought I'd start by checking out a BBE treated intercooler first. To be honest, my real agenda with regard to coating the intercooler was to hide it. I needed something that would camouflage the intercooler without insulating it. Any benefit due to heat emission would be gravy. BBE fit the bill nicely. Swain does nice work and has a staff that is competent and friendly but have been less than supportive of the northeast SR20 community. They refused, as did Stillen, to be even a token sponsor ($20 gift certificate) of the SER Club of America's (northeast region) Salt Fest 2K event. They also refused to give SERCA NE a tour of their facilities during that event. I can understand some reticence on their part in granting 35-40 people access to potentially dangerous areas of their facilities or vulnerable intellectual property; but I'm sure these issues could have been dealt with. The refusal to make even a modest overture to a potentially significant revenue source makes absolutely no sense to me. I guess our loose-knit group just doesn't have the clout others have. They had no qualms about taking my cash though. |