A community of enthusiasts dedicated to Nissan's SR20DE/SR20VE/SR20DET engines.
Start here: forum search. Be sure to search on what you're looking for before posting a new thread.
You are currently browsing the forum as a guest. In order to access special features, the image gallery, and post you will need to be a registered member. Registration is fast, simple and absolutely free so please, join our community today!
If you have any problems with the registration process or your account login, please contact the administrator.
Last year we made 185 WHP with a stock high mile bottom end, S5s, Gen 6 header, ported head and calumsult ECU tuning.
Over the winter we built up a new motor. the specs are:
300ZX pistons
same head as last year, but added supertech valves, RR lifters, '98 rocker arms, double guides on the valve shims for valvetrain stability
C3 cams
O2 induction intake manifold (same as the one 'Dre used 4 years ago, it made him 8hp with a similar setup)
Gen 6 header
ECU tuning (tuned to ~13:1 AFR).
We went to the dyno yesterday and no matter what, the car would not make more than 155WHP
The power is peaking at 6700RPM and falling off hard.
I am really baffled, as the only differences from last year are the cams, built bottom end and intake manifold (all which have been proven to work) and somehow I am down 30hp, when I should have gained 15-25hp.
I did not play with the cam timing. It is just too far out from what it should be (power wise) to have cam timing make 25% more power.
Any ideas?
__________________
Climate Change skeptics are the new Flat Earth Society
if power is peaking early, then there is a timing or air flow issue. the cams could be advanced a lot, poorly ported head, poor intake flow, or something of the sort.
Yoshio, in Toronto. He has tuned 100's of cars. We started using our Calumsult ECU but for some reason it would not burn new chips A car we compete against went to him and made 187 WHP with a gen 5 header and stock intake manifold.
Quote:
if power is peaking early, then there is a timing or air flow issue. the cams could be advanced a lot, poorly ported head, poor intake flow, or something of the sort.
The head is the same one we used last year. It made ~10HP when we swapped it on last year.
It has a 63mm throttle body, 3" intake pipe and JWT POP. Same as last year.
Quote:
make 100% sure you dont have a cam thats a tooth off !!
I assembled this motor myself with a brand new timing chain. I am pretty sure it is correct, although I could always check. Big PITA to pull the timing chain cover though.
You can't just put double guides on you valves? Can you? I just shimmed my set because I know thy have to be level. Thought I'd ask...
Good observation. I had the machine shop file down the valves so the stems are at the exact same height. I also had to modify the rocker arms slightly so the right side of the rocker arm would fit inside the guide.
Quote:
I would dyno throuhg the stock intake manifold just for comparison sake. That and make sure the cam timing, base timing is set right!
Base timing was 20°, but Yoshio set up the computer for 20° base. He tried a few maps, it made a bit of a difference, a few hp but after the tuning we were still at 155WHP.
dont s series cams like it at stock timing not advance been your at 20??? when stock is like 13-15?
__________________
HEY ALBERT PANZIE!!!! all i gotta say is....
15.135 @ 92.63mph and 15.318 @ 93.82mph...nuff said..no rhymes needed here to poet your a** haha
dJ gNO cYDZ.................. RIP DJ SPEEDY!!!!!!!!!!!!!!
Just thought I'd throw this one in there, but are you using the same dyno as you did the first time and has it been recently calibrated?
__________________
1998 Nissan Sentra SE
Mods: SS AC Header, SP1 catback, AEM CAI, Hypercos, AGX, ME mounts, 22VFs, Bobcats, Powerslot, SS lines, Fidanza Fly, ACT clutch, UR Pullies, B&M shifter
When you had the s5 cas installed, was the head ported for the most efficient flow for the s5's? If this is the case, then that could be the reason why you are not getting the power output you should be getting, because the head is not flowwing as efficiently with the c3 cams.
ur not going to get a miracle awnser!
Make shure ur Throttle sensor and all is correct!
Then swap back the S5's and go do a power run! it would be the only way into finding the problem! Cams on these engines tend to be very picky! test it!
Only then ull know! swopping the cams should take longer than 1-2 Hours!
I just spent four fukcing hours on the dyno. I was up past 4AM every night last week getting this thing running and made it into work for 8AM. Don't call me lazy
I don't have the S5s anymore. A cam change shouldnt be more than 40 minutes,
I have come to the conclusion that the cam timing must be off. I need to find a way to degree the engine, but I don't even know where I should be setting the lobe centres. I'll email JWT and see what they recommend.
I say the problem lies within tuning of the timing, and cams. 30whp is like wtf. Also like before mentioned, maybe the head and cams arent working well. imo 195-200 hp is realistic for this setup depending on how high you rev the engine.
)
