Pettersen

iTrader: (1)

So not to far away from starting building the intake manifold for my semi pp engine, so have anyone done any reasearch into wich length is best for wich rpm's? And proven it with dyno runs?

I was thinking something like this:
http://forums.neons.org/viewtopic.php?t=294784

j9fd3s

iTrader: (3)

https://www.rx7club.com/showpost.php...1&postcount=18

Pettersen

iTrader: (1)

So i have been thinking, and i drew up more or less how i plan to make my intake.
2*42mm for the pp's and 2*42mm for side ports.

Any tought's?

j9fd3s

iTrader: (3)

that's how the stock ones are, except yours are so much bigger

Pettersen

iTrader: (1)

Stock ones? You mean the t2 intake? Isn't that 3*45mm?

j9fd3s

iTrader: (3)

the throttle body is, they don't actually say what the runner size or length is on the T2. there are papers on the GSL-SE 13B and the 89-91 NA 13B though, so we know what those are, the runners are more like 36-38mm

F1Pilot

Sounds familiar!! Have you had the ports made yet?

Im sure you have seen my thread, but for info, Im trying 40mm primaries and 45mm PP.

My length ended up around 450mm for primaries and 400mm for the PPs.

Im guessing thats too long to suit the peak power of that port configuration, but it does have to fit in my car!

Anyways, with a 20B PP......Im sure power wont be too much an issue.

Pettersen

iTrader: (1)

Yes the rotorhousings are already ported. Fairly small pp's as you can probably tell from the drawing..

j9fd3s: I tought you where aiming at the tb's, i was planning on port matching the runners.

Pettersen

iTrader: (1)

I'm going to run stock rpm range for now, so i feel that shorter runners just would put the power out of reach, tho i havent any real knowledge to go from, just guestimating from what little info i have found.
Somewhere down the line i want to get the car on a dyno, and test some different runner lengths, to see wich gives the most usable power below 7500rpm...

Since this is a 13b semi pp, my power goal isn't realy that high, i will be happy if i pass 220whp(what my turbo engine had).

Pettersen

iTrader: (1)

forgot to mention that i decided on 450mm for the pp's and 550 for the side ports.

John Huijben

iTrader: (1)

I'm not sure if having different intake lengths would be good. Might spread the power out a bit, but maximum power will be lower. I think I would make the intake lengths equal, by making the side port runners a little bit shorter than the pp runners because of the longer intake length inside the engine.

Pettersen

iTrader: (1)

Logan has shorter pp runners, and his semi pp 20b made 475rwhp.
https://www.rx7club.com/20b-forum-95/n-20b-hits-record-475rwhp-979689/


And spreading the power out is one of the reasons i'm building a semi pp in the first place. I think it should make for faster lap times, if the drop in max power isn't to great.

John Huijben

iTrader: (1)

Yes logan did have shorter pp runners, but I believe he wired those so that they were only activated at higher throttle openings. So the p-ports weren't always open which means most of the time the engine was only using the longer runners which under lower rpm's and loads is benefitial. If the p-ports are open all the time you don't have this benefit. Don't get me wrong, the engine will run great and make a lot of power with an intake like this, I really like the design but don't just use short runners for the p-ports and long runners for the side ports because p-ports are for high rpm's and side port's are for low rpm's. That's just bogus if you ask me. Might be a good idea to fabricate the airhorns in a way that they can be replaced with different ones so you can test different lengths when your unhappy with the engine's rpm-band or performance.

Pettersen

iTrader: (1)

The tb's will be mechanicly staged, so the pp's won't open under 30% throttle opening or more. Also the gsxr itb's i'm using came with two sets of butterflys, one mechanicly operated and one ecu controlled, so i will be testing with ecu controlled pp butterflys down the line, could also try to switch it up and open the pp's first(but that's something i can do further down the line).

I think i will have fairly short airhorns, and have a interchangable runner between them and the tb's, that way i can test out some different air horns. I need to invest in a Vbox or gtech so i have something to measure the differense with...

mikey D

cool post by the neon guys been wanting to try this

Pettersen

iTrader: (1)

So plans have changed, got some advice from some members wich turned me away from sequential throttle control, atleast at this stage.

Going to modify the T2 LIM(since it means i can use the stock fuel system, and i can't realy afford to fit that into my budget at the moment), and make a new UIM.

The modifications i plan to do on the T2 LIM for it to suit my build:
Fit a runner from pp's to the primary runner, and port up the primary runners from where the pp runner is connected up to the flange.

Here is a sketch of how i plan on building the UIM(can't figure out how to make bent piping in sketchup without using a lot of time, so the lines from the flange to the tb's are supposed to be 42mm ID pipe.)




I have all the parts i need, so i will start on the UIM today.