Fading Top End
 

Well,

I've got a problem that I've noticed here lately....in my top end, from 6,800 - 8,000 rpms it feels like my power just is NULL and VOID! :P

I mean, I went from beating a S2000 to I hit that top end and it was over, he flew past me after I hit my top end, I was beating him before that (0-85 MPH) at about 90 MPH is when he took me out.

Also, I'm beginning to wonder if this car has a ported motor in it because it's pretty fast...faster than my tbird and girlfriends camaro, the GF's v6 camaro was doing a 15.6 1/4 and I'm whooping the snot out of her car, also whooped the snot out of the v6 6-speed mustangs that just came out, haven't gotten the chance to run the v8 or anything like that.

It's also a whole lot faster than my tbird which was doing 15.8 @ 91 MPH.

But, my question is, my power is whole lot stronger mainly from about 3k rpm to 6k rpm then you can literally feel the power fade fast.

The fuel filter hasn't been changed but it smells like it's running rich when I first start it up.

TII or N/A? Sounds normal.

yeah... you definiitly didnt beat a V6 6-speed mustang, especially any that just came out. there are no 6speed mustangs anymore... and there never was a 6sp v6 car either...

check your VDI andmake sure it opens at 5000rpm. it sounds like your losing top end airflow or something.

of course perceive speed can be considerably different than measured speed. my car FEELS alot faster with my new mods... but if you ask ANYONE here, they will tell you that its impossible to be faster than stock.

you shold try to take it to the track and see exactly what its doing. it might have a decent 1/8 mile time but have a bad 1/4 mile time. or you could just dyno it and see where the power falls off and youll see what your fuel curve is like too

Sorry, I could have swore there was a v6 6-speed either way, I beat a newer v6 mustang! :bigthumb:

And no, when I'm keeping up with S2000's until the power fade happens I think I'm doing pretty good.

It's N/A

Hey,

Also, I've got a question, if it's a NA, is there any good in tunning it, I know I would have to see someone but what equipment is needed on my end, an SAFC?

A S2k should beat you hands down. So if your keeping up at all congrats!

Yes a SAFC II would be a great mod for a NA with an exhaust an CAI.

Couldn't agree more, best and only mods that should be done to an NA ;)

The exhaust is stock, and rotted out (big exhaust leak) so I think that's why I'm loosing power up high, that or the fuel filter, or its just tuned wrong!

Are you guys being sarcastic or is it really that much better for the N/A? I'm looking to get the most out of the motor before I go boosted.

I do however have the intake going, cone filter + heat shield made by Mike Zeda...

technically an exhaust leak will increase your hp lol.. as its more free flowing. and will help your top end.

unless your car is indeed ported, then your peak hp is around 6500-7000 anyway... meaning your over reving, and power naturally drops off past the peak...

a clogged up catalytic converter would cause power loss at high rpm.

yeah, i think that Rotaries are tuned on the safe side of things from the factory and can stand to be leaned out a little bit more with an SAFC. check into that.

either way, a V6 stang and an S2000 are pretty decent for an NA FC to keep up with. if youre hanging w/ an S2K, thats admirable.

i would look into a true dual header and exhaust system for your application. youll see some promising returns from it.

You're not supposed to be beating S2K's.


-Ted

Ummmm..... Not necessarily......

N/A's with leaky exhaust, or free flow exhaust exhibit two common problems...

1) they run rich

2) They lose power at High RPM

Losing power at High RPMs is in part cause by the running rich, but, on s4's its worsened if there is too little backpressure on the exhaust (like, a leak!!!!) to open the 6-ports....

So here I come exhaust and SAFC.

Trust me, I suprised my self when I ran the S2000! I kept hearing 16.2/16.3+ and here I am keeping up (until i hit the dead spot argh).

The S2K owner either didn't know you were racing him, or he doesn't know how to drive the car properly.
The launch those VTEC bitches, you need to rev the shit out of them on the launch.
If you launch the car under the VTEC trigger RPM, it launches pretty lazily.
Launch the bitch over VTEC and watch out...


-Ted

We were going from a roll...it was more in my powerband but as soon as I hit my high RPMS it killed my cars speed, even the S2k owner was asking me what happened.

PS, when people ride behind me at night and I shift fast/ride it hard they say they see a mini-flame every time at high-rpm's, bigger than a back fire but not a backfire, I assume this is normal from it running so rich.

I'm defintley suspecting the cat's being clogged....here I come full exhaust!

The s2k asked you what’s wrong b/c he realized how easy it was to walk away. Non the less it should be easy for him that’s a 250hp car that weighs less as well and turns I think it was 13.2 1/4 anyhow its 1 second faster then the rx8.

Go to a H dealer and drive one. If you still wan to beat one take everything I have below here and add a street port and a 75shot or N20

Get the larger H prelude CAI setup off ebay and mod this for a CAI. Order your full exhaust you chose and a SAFC II. My final suggestion to someone who will do there own tuning is get a wide band AF gauge.

Ted has a point, those S2K's have Madd Vtak Yoo... Vtak Pwnz Joo!

im not so sure a clogged cat is going to cause you to shoot flames when you shift. you may have a bad AAV, punched out cat and just running usually rich. sort out your exhaust and tune it with the safc. you should be good to go.

No, it wasn't easy for him to walk away from me until I hit high-rpms, then he pulled back out in front of me and spotted me maybe a car and a half total by the end of the race (from about 100mph to about 125mph).

I think a 25mph race qualifys as a ricer fly by. They will do 150 and pull there strong. Race one from 1st or second gear on. He will just up and leave you. Sorry but it is the truth they are quick cars.

It was me, the S2000, a 350z, and a first generation talon (DSi or TSi?) and we were all taking off and doing the three honks, the first two up were the 350z and 1st gen car and they were side by side then the 350z finally pulled ahead.

The second race was my self and the s2000, three honks and we both gunned it, I was ahead up until hit 6k rpms and then I felt the power slipping at about 7k hard so I shifted into the next gear and in that little time frame he managed to slip off.

I'm not denying that the S2000's are fast cars, I stated that they were in the beginning. I'm just saying, that he came up to me after the race asking why I was beating him then it seemed like I lost all my power.

I didn't know, so I came on here to ask questions, not to be called a ricer...which by the way I'm not thanks very much.

A race from 100mph to 125mph isn't a ricer fly-by as well, you missed the 1...we were on the interstate at like 2AM there wasn't a fly out there.

Well, probably whats happening is when you hit 6k, his vtec is just kicking in,too. You ever drive a v-tech car? Fast..... :eek: takes a second to get going in some. Won't kick in till around 4800-5500 depending on whether he has a v-tech controller or not. :eek:

Yeah, I guess that's true, almost like a little turbo spooling up.

Come to think about it, that's probbaly what's happening, I'm beating him until the VTEC happens then I get screwed.

Anyone got any approximate HP figures that VTEC adds from one before VTEC kicks in? I'm kind of interested to see where I'm going to have to get to beat one.

have you ever checked the trailing spark plugs?? dat could be it.