What to do for more power 4k-6k rpm

[apzak]

I use 4k-6k rpm whenever I'm passing cars or just having fun, and could use a stronger pull. What do you guys suggest I do? I was thinking JWT ECU would improve power through the rpm range, or atleast thats what their website says. What about cams? I do alot of highway driving so need more power in 4th and 5th gear. (4th mostly) I heard cams only start working at 5k rpm though, and I'll loose power where I need it. But, will cams give me more power in the higher gears (higher speeds) no matter what rpm?

oh yes, if you cant see under my name I already have Injen Cold Air Intake, Hotshot Headers, and Apexi N1 catback.

[klattr1]

i have jim wolf cams. I even used them naturally aspirated and there is definitely a noticeable increase in the upper rpms.I would say they "kick" around 4000 rpm.

[LiU]

apzak - i have the jwt cams also, you lose some low end but they pick up around 4000 and is hella nice after that.

I don't mean to thread jack but I have the same question, I am considering between an SAFC and the JWT ECU (would like some more power and also better fuel economy when I'm not stepping on it ;]) the SAFC I can get for less than $250 on ebay or somewhere the JWT ECU is $500. I was wondering for those of you with JWT or other cams and JWT ECU, was the increased rev limiter worth it at all in your honest opinion? Did power drop after 6400 (stock redline on s14) even w/ the cams?

thanks

[klattr1]

throttle response is also one advantage of jim wolf ecu

[:: orion ::]

AFC and JWT both lean out the fuel curve, but AFC won't give better timing advance...

Leaning out an N/A car will not give huge gains (maybe 1-2hp), but adding some timing advance, removing the tip-in retard function (backs timing off for a half-second when you stab the throttle, to prevent knock - It's an outdated function still built into Nissan ECUs), and uppping the rev limiter, all which the JWT ECU does, will yeild MUCH larger gains.

I'm not the biggest JWT fan...BUT, they make a decent ECU for the N/A 240SX...

You can spend half the money on an AFC and get 1-3hp *maybe*, or spend $500 and get closer to 8-10rwhp...especially with their cams already installed - You need the revs.

Later - Brian

[apzak]

sounds good, i'm probably going to have to pay someone to install the ecu because it needs to be a 96 ecu and some minor modifications to make it work on the 98. jwt doesnt program 97-98 ECUs. oh yea, leaning out wont shorten the life of the motor? And i could expect better gas mileage with a leaner fuel setup?

[LiU]

no it won't shorten engine life, yes better gas mileage...

so taht's 1 vote for the ECU, any others?

[Exar-Kun]

I got 7hp from my S-afc, thank you very much. I'll be coupling it with a Z32MAF and JWT ECU and cams soon. Just hought I would correct you about not gaining any HP from it...you gain quite a bit across the power band if you tune it right(dyno, wideband 02, and a lot of knowledge)

the last time Irmetuned to the new header I gained 9hp from 2900 to 4400rpm and another 7 from 5600-6300, but only 2hp peak.

-chet

[LiU]

i suppose to get the most possible from an safc would be dyno time.. which would be $$, and would probably add up to the cost of a JWT ECU.

for the new redline of 7000 you guys think I would need more headwork in addition to the cams? (springs, retainers? ) or will the stockers hold fine

[Altiman94]

intake/header/exhuast and cams.

[LiU]

hmm thanks for the reply, but that's not what I was asking

[Exar-Kun]

the stock valva train should hold finr to 6800 or a little above, but if you want to give yourself that extra measure of safety, get the springs and retainers upgraded, also, I've seen the dyno numbers from a ported and polished and a standard KA24DE head, the numbers arent signifigantly different, I would reccomend a really nice valve job(radiused) and extrude hone the head, if possible.

-chet

[LiU]

the only springs and retinaers I've found so far ar ethe ferrea ones, anything else out there? I did a thread on this awhile back but didn't really get many solid answers. Thanks.

[LiU]

nvm I found some stuff on http://www.ka24de.com .... they have alot of nice stuff and it iwllb e interesting to see what they will have coming up soon.

[doh240sx]

to original thread poster, is your apex catback made for turbo? just wondering cuz that would probably lose you couple hp since you're na...

[Altiman94]

^no it won't. Your engine doesn't need any back pressure to run. If it did, you wouldn't be able to run open header and actually see gains from it.

[Exar-Kun]

actually, on a n/a engine some backpressure is good, it prevents backfilling of the combustion chamber. And yes, you can actually watch too large an exhaust drop Hp DOWN on a dyno, esspecially in the lower RPMS.

the benifit of low backpressure is most pronounced in turbo and high copression/high revving N/A cars(ones tat flow a ton of air/fuel).-chet

[pstickne]

I have always read (yes, nothing more :-) that (for a NA) the exhaust should be matched to create a quick flowing exhaust stream that will act like a vacume and help to empty the combustion chambers.

"Backpressure" on the other hand, never adds perfomance AFAIK.(When would backpressure ever help to empty out the cylinders?)

One thing I do not fully understand is, why not have a fairly restrictive exhaust manifold that opens into a much wider exhaust as the smaller diameter piping would have a [much] faster exhaust stream close to the ... well, whatever you collectively call the start of the "exhaust system" ... in adition to having a less restrictive (albiet slower-flowing) system farther down.

Edit:Read this (I'm doing it right now to help reduce my ignorance):http://www.warnertechnology.co...shtml

Edit2:http://webhome.idirect.com/~trini/car/muffler.html"Also, terms like "back pressure" and the statement, "An engine needs back pressure to run properly!" really rub us the wrong way."