no bottem end???

[rob_n13]

i've heard about this dreaded flat spot in the sr20de and unfortunatle i've got it but i'm wondering if it's just me or do all the sr's have verry little bottem end :nightcap: . by this i mean the engine just sortat slowly makes it's way up to about 3800 - 4000 before she starts to noticabley pull. i've advanced the timing to around 15-17* and run it on BP Ultimate and taken out that piece of crap that goes from the air box around the battery, apart from that it's stock as a rock any help would be great.

cheers rob.

[NXT51]

Do you have a skyline R31? or an N12? or an NX like you'd hoped for?

Hmmm, the dreaded flat spot is usually around 2000-2500 rpm and is a stutter/loss of power/ugly-noisy-painful series of lurching (*note symptoms may vary*). The SR20 naturally does not really pick up it's power until after 4000 rpm (just like most top-end 4 cylinder cars) - to really get the car going, all the power is at the higher revs... so maybe your car's just normal.... BTW there are heaps of threads out about the flat spot - do a search to read more about it and check out pulsar.org.

cheers :dj:

[Herbs]

yeah as nxt51 said, most higher end twin cam engines dont produce any power untill about 4000rpm, this is when the cam profile becomes more agresive and alows alot more air and fuel to enter the cylinder head (peak power in my car is 86kw at the wheels at 7100rpm - mercury motorsport dyno).
As for your flatspot it could be a number of things if not all of them....... Just read, read and read some more and try things that you feel comfortable doing.

[rob_n13]

the flat spot isn't what i'm woried about i know it's common and that it can't be fixed what i am worried about is the lack of bottem end so what i'm getting out of your answers is that it is common for the sr to not produce much grunt untill it reaches about 4000 rpm. next question. is it fixable with different cams ect. in other words is there a way to flaten out the power curve?

thanx for the info so far.

[tissue]

You could get big cams and cam gears and dial back the peak power by a few degrees, but then you will have no top end and fuel economy will drop. Another way is displacement.

Have you thought about a lightweight flywheel with crank pulley? It wont give you more torque, but free up what you currently have.

Ive noticed this lack of torque but only compared to 6s and 8s. Most 4s dont have near the torque of a sr20. Just one of the downsides of a 4 cylinder, it seems like you have to dump the clutch to get it anywhere.

[Herbs]

yeah aint that the truth tissue!!!!

if you wanted instant low down torque and aceleration by a turbo or go back to the single cam engine, you'll spend huge dollars on a twin cam N/A engine to get it to do the same.....

If you wanted a mild improvement down low, buy and Apexi SAFC and get it tuned on a dyno, they'll make it run a bit richer through the lower revs to try and load the engine up a bit and they will lean it out up top, this will give your more power the whole way through the rev range but not neccesarily flatten out the power curve. This will also give you better fuel consumption, i did this to my car and noticed the difference.

[Herbs]

was your previouse ride a 1.8ltr n13, if so dont expect the sr20 to behave the same down low, i had an 1.8ltr LD astra which is identicle to the n13 pulsars, it went well till about 5000rpm, whereas the sr20 wont go well untill 5000rpm.

Perfect example, i used to race my mates sss pulsar when i had my n13, if we both started in 5th i would easily beat him and he wouldnt catch me, if we raced in fourth i would jump him and then he would pull past me around 140kmh, if we both started in 3rd we would stay side by side for about 2 seconds then he would pull away from me like no tommorow.
You have to be more agressive to these things to get em to go well, thats half the fun.

[rob_n13]

thanx heaps for the comments looks like it's one of thoes things i'll have to get used to and Herbs, yes my last ride was a 1.8L n13 Q and i hear what u'r saying about it dropping off at 5000rpm i useuly dident go past 5500 cause after that it did nothing but make more noise. excuse my ignorence but whats a SAFC just out of curiosety.

cheers rob.

[nexis]

Well everyone is correct.

But i personally wouldnt really want to spend too much money making a sr perform in the 2 to 4000 rpm area. Its like driving a turbo car off boost. There isnt really too much point.

If you wanna go qik, you drive it where your power band is. If you want to drive agressively (say on a track) you can do so with out going under 4000rpm therefore staying constantly where the power is.

[chris2]

the flatspot is a bitch i have tried just about evereything and conclude its an eccs problem, probably a component goin out of tolerance, they didnt have it to start with but it creeps in on all of em whether its an n14 s14,s15 ,nx you name it, the only way to get rid of it is an aftermarket ecu!
sr20 actually are pretty good for tork off the line as well as bein a revver, its fucken annoying cause it really jerks a bit and then sometimes (rarely) not!

changed/replaced:
dizzy cap and button
leads
fuel filter and pump
different regulator
new tps
new O2
new transistor
different AFM
triple checked all connectors

oh and i used to have a familyII (camira)2 litre i put a vn throttle body on it and drilled the fuck out of the airbox and could do accords and telstars no problem!

Nissan cant fix it either, i got a lot of this shit for free cause they couldnt solve problem and i made a fuss about the labor + parts. there consult didnt no either!
they told me to fuckoff !

[Herbs]

an SAFC is a "Super Air Flow Converter" which is made by apexi. It controls the air flow that the computer gets and can alter your fuel mixture, go to www.apexi.com and have a search for it if ya want to know more about it.

[MaxNx]

Tissue mentioned it earlier in the thread, and it's an option i am still seriously considering. Lightened flywheels can apparently make a huge diffrence in how fast your car revs in low gears.

Associated problems with this route is that they require more revs of launch so you don't stall (lack of weight means when the flywheel comes into contact with the clutch plate it's more likely to stop than move the parts required to move the car) this can make it hard to find the fine line between spinning wheels and bogging of the line. I've also heard you lose some torque.

But i've still yet to find a person who has one that complains the problems outweigh the insane way the car revs out.

That's my 2c (possibly closer to a full $1 though)

[rob_n13]

cool that sounds like a good option once i get some money together i was going to get a LSD, i miss my LSD, so i may aswell put in a decent cluch and flywheel while i'm at it.

[Pretty White]

Do you have a cat back exhaust?
Try a nice 2-2.25" exhaust.
Also try cleaning your T/B and see if that helps any.