GT2 Posted May 11, 2018 Report Share Posted May 11, 2018 Does your engine have an adjustable cam gear? Maybe you can retard it a hair and move your power range up a bit? Careful, don't want to bend any valves! Quote Link to comment
GT2 Posted May 11, 2018 Report Share Posted May 11, 2018 I have never heard this before, Dyno numbers? This is quite common in the race world, Ive seen many a manifold with port putty in it. 1 Quote Link to comment
datzenmike Posted May 11, 2018 Report Share Posted May 11, 2018 Z-train has a somewhat 'dune up' 2.3? with what I would call a restrictive port head on it. HP is ok but the torque numbers on the dyno sheet are very impressive through the mid range. Now if someone could just invent a morphing intake runner and head port that expanded with RPMs..... Quote Link to comment
Stoffregen Motorsports Posted May 11, 2018 Report Share Posted May 11, 2018 You don't need an adjustable cam gear to adjust your cam timing. Using a cam degree bushing from Comp Cams, Mr Gasket, Crane Cams, etc, you simply drill the alignment hole in your cam gear larger, insert one of these bushings and tighten the bolt. You will need to play around with them until you get the desired cam timing. These are safer than adjustable cam sprockets because they can't come loose while revving the piss out of your motor. 2 Quote Link to comment
Stoffregen Motorsports Posted May 11, 2018 Report Share Posted May 11, 2018 @Scooter, I'm with the rest of the guys here. Having a plan of attack on a port job is much more effective than throwing your porting tool at it. Sometimes simply un-shrouding the valves, blending the seats and opening up the bowls is all the "porting" an engine needs. A bad port job can hurt power. Sometimes you don't even increase peak power with a port job, but smooth out the power curve. That's a win in my book. 2 Quote Link to comment
mhub91 Posted May 11, 2018 Report Share Posted May 11, 2018 I don't have access to the Dyno sheets. I would happy provide them but I recently left the tuning shop I worked at. Often times people think bigger is better. I get it. In nature this is almost a fact. But This can easily be disproved by looking at automotive as a whole. For example, a Nissan SR20DET can easily make comparable power to a Corvette. A B210 can have identical MPG to a Prius. Air velocity speeds of an R1 motorcycle can be achieved with small intake ports from any engine. This topic is heavily documented in near-vintage literature topics of automotive performance. Quote Link to comment
datsunfreak Posted May 12, 2018 Report Share Posted May 12, 2018 Now if someone could just invent a morphing intake runner and head port that expanded with RPMs..... The first one has been done for awhile now hasn't it? Quote Link to comment
flatcat19 Posted May 12, 2018 Report Share Posted May 12, 2018 The first one has been done for awhile now hasn't it? Damn near every maker has a variable intake manifold in place on their cars. Quote Link to comment
datzenmike Posted May 12, 2018 Report Share Posted May 12, 2018 I doubt it's what I'm thinking. Not variable length. Variable cross section to increase air speed but expand as the volume increases so it's not restrictive. Air speed is optimized at all RPMs. Quote Link to comment
datsunfreak Posted May 12, 2018 Report Share Posted May 12, 2018 Variable cross section to increase air speed but expand as the volume increases so it's not restrictive. Air speed is optimized at all RPMs. Nissan has been doing that since around 1988... Quote Link to comment
datzenmike Posted May 13, 2018 Report Share Posted May 13, 2018 How does it do this? Quote Link to comment
datsunfreak Posted May 13, 2018 Report Share Posted May 13, 2018 How does it do this? Butterflies that only block part of the intake path, then open slowly as RPMs increase. More of a venturi really, but similar net effect. 1 Quote Link to comment
datzenmike Posted May 13, 2018 Report Share Posted May 13, 2018 Those are for inducing swirl at very low speeds and idle. KAs had em. I mean some way to make the ports increase in diameter to flow more but shrink at low speeds. Quote Link to comment
flatcat19 Posted May 13, 2018 Report Share Posted May 13, 2018 Toyotas long runners are wider then the short set. Quote Link to comment
datzenmike Posted May 13, 2018 Report Share Posted May 13, 2018 Length can tune for positive pressure waves but they are not variable just long and short, on or off. Quote Link to comment
flatcat19 Posted May 13, 2018 Report Share Posted May 13, 2018 SMH. Old people. Or partially open, using both sets of runners. Also while using variable intake valve open, closing. Variable size/volume and length achieved. Not what we're aiming for in this thread, but yes...your invention has been made and used for years. Maybe not the exact way you speak of...but I'm pretty sure these engineers have things covered pretty well. 3 Quote Link to comment
mhub91 Posted May 13, 2018 Report Share Posted May 13, 2018 Check out mazda's VRIS System. "Variable Resonance Induction Chamber". Quote Link to comment
Tom1200 Posted May 13, 2018 Report Share Posted May 13, 2018 So back to A-series porting; on the cylinder head I did, as mentioned I blended the seats and worked on the bowl area. On the head I bought from Peter Zekert, the seats were blended, it had a little more material removed around the valve guide and there was some unshrouding of the valves. The unshrouding wasn't as much as one typically sees on a L series head. The only reason I didn't do any unshrouding on the head I did myself was simply down to the fact of my being unsure of how much to take off. If you had a bone stock A12 -15 and simply cleaned up the ports you'd likely pick up around 5hp. Using the GX head gasket would increase the compression enough to pick up another 2hp. So you could pick up 7hp for $75. Just as a comparison I'll share this: yesterday I ran the 1200 at a track and the difference between the A12 that's in there now and the A15 that went kablamo is more than 10mph at the end of the two longest straights. The A12 has 20 less horsepower, while that's a big difference the 20% reduction isn't huge (like 140 to say 80). Also because of the reduced power the car also won't pull 4th gear as well coming off some of the medium speed corners. Whereas the car used to get 9 mpg it now gets 15mpg. So back to Tim's A14 powered car. A camshaft upgrade, better flowing valves and cleaning up the ports would fit his $700 or less budget and very like net a 7-10mph increase. 3 Quote Link to comment
TimGreen Posted May 14, 2018 Author Report Share Posted May 14, 2018 So back to A-series porting; on the cylinder head I did, as mentioned I blended the seats and worked on the bowl area. On the head I bought from Peter Zekert, the seats were blended, it had a little more material removed around the valve guide and there was some unshrouding of the valves. The unshrouding wasn't as much as one typically sees on a L series head. The only reason I didn't do any unshrouding on the head I did myself was simply down to the fact of my being unsure of how much to take off. If you had a bone stock A12 -15 and simply cleaned up the ports you'd likely pick up around 5hp. Using the GX head gasket would increase the compression enough to pick up another 2hp. So you could pick up 7hp for $75. Just as a comparison I'll share this: yesterday I ran the 1200 at a track and the difference between the A12 that's in there now and the A15 that went kablamo is more than 10mph at the end of the two longest straights. The A12 has 20 less horsepower, while that's a big difference the 20% reduction isn't huge (like 140 to say 80). Also because of the reduced power the car also won't pull 4th gear as well coming off some of the medium speed corners. Whereas the car used to get 9 mpg it now gets 15mpg. So back to Tim's A14 powered car. A camshaft upgrade, better flowing valves and cleaning up the ports would fit his $700 or less budget and very like net a 7-10mph increase. I really like this idea and probably should consider buying a stock A14 head to modify so I don't interrupt the summer race schedule. This way he could possibly have the extra power for the September/October races. This weekend we removed the axles, changed the diff to the 3.89 (locker), changed the water pump, reinstalled the freshly cleaned radiator, and some other minor maintenance. We are looking forward to the two races over Memorial Day weekend, Any ideas on the cost of an stock A14 head? 1 Quote Link to comment
mhub91 Posted May 14, 2018 Report Share Posted May 14, 2018 $40-$300 bucks. Depending on seller. Unfortunately that's how it is with literally all Datsun parts. I've got the rarest of rare parts for dirt. And then I've seen 4sod B210 trans for $200 (which should be free). 1 Quote Link to comment
datzenmike Posted May 14, 2018 Report Share Posted May 14, 2018 I bought a 5 speed dogleg for $20 once. 1 Quote Link to comment
Stoffregen Motorsports Posted May 14, 2018 Report Share Posted May 14, 2018 Me too. The dogleg 5spd I had in my 320 with an A12 came from a wrecking yard for $20. Tom, your info is great. It makes me want to get another A series just so I can build it your way. 1 Quote Link to comment
racerx Posted May 14, 2018 Report Share Posted May 14, 2018 $40-$300 bucks. Depending on seller. Unfortunately that's how it is with literally all Datsun parts. I've got the rarest of rare parts for dirt. And then I've seen 4sod B210 trans for $200 (which should be free)....specially when they say "JDM" then the price just quadrupled. 1 Quote Link to comment
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