Datsun Roadster Forum-311s.org

I use similar to your first version, but stepped up design, in two steps

It's a stroker 2260cc running 48mm webers. felt like we hit the limit of the carbs at 226hp

Well, they make these in 48mm (and 40mm, 45mm) sizes! Jenvey Heritage throttle bodies. Look just like your Webers, but they're not! EFI. I'm getting close, waiting on some banjo bolts for the fuel lines before I can run fuel through the system and check for leaks, then download the software and start tuning. Every bit of this is a new/first time for me, so I'm learning as I go!

Make me a header!!! Love that thing...

Wow they really do look the same. 48mm throttle bodies will flow more than the webers as they don't have chokes/venturis inside - so they will be plenty big enough

Yes, they were made that way specifically to look the part in a classic car. The round cap for example is just for looks and is not removable. Just to clarify, these are 40mm, but they do make larger sizes if needed.

WOW! That's impressive.

Wanted to post this for those thinking of a cam in their SR20s
after doing much research on potential cam and tune for my normally aspirated S13 SR20DE I finally opted to go with the Tomei Poncam , there's not a ton of reviews but every single one was positive and lauded the increase in midrange and gains all over the powerband since this is what I wanted and add to that that they were less expensive then the other options , it was a no brainer.

In speaking with various tuners in my region it was decided that a Nisstune type3 board would be best suited to my car so we went with that

Brand: Tomei
Product: Camshaft Poncam Set - S13 RS13 SR20DE
Part Num.: 143040

SPECIFICATIONS:
Duration (degree):
- Intake: 260
- Exhaust: 260
Max Cam Lift(mm):
- Intake: 7.23
- Exhaust: 7.23
Max Valve lift(mm):
- Intake: 11.20
- Exhaust: 11.20

the first picture is of the graphs done at the tuner unfortunately that's all I got from him, from what I understand the pulls were done in 3rd gear which I'm told gives lower torque values , it was also very hot (100f) an humid that week. I wasn't there for the pulls so I have to go with what I was told , we initially did 117whp and 107ft-lb which I thought were a little low numbers but i was more concerned about the gains we would achieve and I wasn't disappointed. After they installed the cams and tune and power increased at 135whp and 123ft-lbs with gains everywhere especially midrange torque .



The car was already a joy to drive but even more so now as it really feels much stronger , much more so than what the numbers showed , the numbers showed that this car was close to Mr Green but the feeling was it was much stronger , since there are a few more changes I wan to make to the car to fix a few power robbing issues (exhaust , intake) and to have a real comparison with Mr Green now that the cam is broken in I took it to the same dyno that's where I take all my cars. (we ran my 260z at the same time ) I also prefer it since he always does the pulls in 4th for a more accurate 1:1 ratio

The car did a very strong 145whp/131ft-lbs , I think the numbers on the torque are more accurate with the way the cars drives , if you take into account dyno variation my real power is probably somewhere between the 136-145 which is very strong for an S13. come this spring we will fix the exhaust and intake and see what happens

again I'm extremely happy with the cams

That's a real nice improvement! I converted the total valve lift to inches and it has .441 lift. Given that your peak torque is right near 4800-4900 rpm I wonder if your 260 duration number is "at 50thousands" valve lift or the "advertized" duration? As a comparison, my Isky cam is at 278 advertized and 246 at 50thousands with a total valve lift of .537 (that's a lot and probably does not need that much lift). Peak torque was at 4700-4800 rpm (same as a typical "B" cam with an advertized 280 duration), though that much lift can move duration up a bit.
The increase in torque is substantial and I have no doubt you can feel it! Looks like the tuner was able to improve things a lot. Just for fun I'd be curious to know what he changed and what made the difference... just the cam, or changes to ignition timing, fuel ratio or both? He got rid of a steeper drop off in high end torque past peak as well. Fun Stuff! Congrats... it's always nice when the changes you make actually work! You'll also have a nice baseline for future mods as mentioned.

Gregs672000 wrote: Wed Sep 29, 2021 11:47 am Looks like the tuner was able to improve things a lot. Just for fun I'd be curious to know what he changed and what made the difference... just the cam, or changes to ignition timing, fuel ratio or both? He got rid of a steeper drop off in high end torque past peak as well. Fun Stuff! Congrats..

Thank you,

What the tuner told me is that the cam by itself would have improved things quite a bit but adding the Nisstune enabled him to remap the ignition spark and fuel at their optimum efficiency for my new engine configuration and take full advantage of the cam and 91octane fuel.

if you look at the AFR on the last sheet (green line) at WOT after 2700 where the run really start i'm almost always between 0.850-0.890 which is really where you wan to be for maximum output, you'll also noticed that at around 4500 he richened it up a little to get rid of the steep drop in torque and keep the power going longer.

What's very interesting is that he was very clear that I'm losing quite a bit of power due to 2 very sharp and close together 90 degrees angles on my Intake (he made 3hp more when removed) and because my exhaust after the muffler is all crushed bent and smaller sized than the front part of the exhaust . he said that with the mapping he has done I could see probably 2-3 ft/lbs across all levels and as much as 10-12 more HP on the top end after fixing these things

Gregs672000 wrote: Wed Sep 29, 2021 11:47 am That's a real nice improvement! I converted the total valve lift to inches and it has .441 lift. Given that your peak torque is right near 4800-4900 rpm I wonder if your 260 duration number is "at 50thousands" valve lift or the "advertized" duration? As a comparison, my Isky cam is at 278 advertized and 246 at 50thousands with a total valve lift of .537 (that's a lot and probably does not need that much lift). Peak torque was at 4700-4800 rpm (same as a typical "B" cam with an advertized 280 duration), though that much lift can move duration up a bit.

I dont fully understand how to read Cam specs , I chose the Poncam mostly from what folks said about it and people's experience .

If you're curious about the specs this is the 258 version for the DET which I'm told is almost exactly the same ans is often used interchangeably

That's interesting. As I read that above, duration is 213 at .05, .453 valve lift. As I understand it, multi-valve heads like different cam profiles due to their typically better flow characteristics.