Hey....
I was just wondering
do we need to remap the ecu if we change the stock cams to the JWT cams?
or even change it back to the 91 SR20DE cams?

Originally posted by pche059
Hey....
I was just wondering
do we need to remap the ecu if we change the stock cams to the JWT cams?
or even change it back to the 91 SR20DE cams?


You do not need to remap the ECU to run JWT cams. However, JWT does have programs available that will optimize the the performance with the cams. Mostly they change the spark map. I don't know the details since it's proprietary information, but I know that those who do know say that at certain rpms they add or subtract spark advance. The cams are very efficient at cylinder filling and that results in the opportunity for optimization of the maps.

They can also change some things to smooth out the idle.

Otherwise, a stock ECU/MAF will yield excellent results and will adapt well to the cams.

I was thinking of gettin cams but my friends told me that using aftermarket in an automatic doesn't do jack.. It is only good for manual....anyone can confirm this??? IM out!

well then if i change the cam
could the red line be pushed back a little bit later then?
according to my S AFC my engine cuts off about 6800 rpm....that's a bit low for a N/A car.....

and what controls the rev cut of the engine? is it the ecu ...? or some hardware devices?


:)

Originally posted by pche059
well then if i change the cam
could the red line be pushed back a little bit later then?
according to my S AFC my engine cuts off about 6800 rpm....that's a bit low for a N/A car.....

and what controls the rev cut of the engine? is it the ecu ...? or some hardware devices?


:)

The solid rocker SR20 will rev to 7850 rpm safely, but that is independent of the cams used. The revs are limited by the hydraulic valve lash asjusters (HVLAs). Over 7850 the HVLAs are not able to keep the rockers in constant contact with the cams and they eventually (quickly) spit out from under the cams. At best this just means having to put it all back together. At worst it could lead to bent valves and buggered cams.

If you have a roller rocker engine, I'm not sure what the limit is. It's probably the same, but I don't know for sure.

The rev limit is controlled by the ECU and is handled by cutting the fuel. It can be rather dramatic in the SR20. The first time I hit it I thought I blew the engine. Last time I hit it was in the SE-R race car. Oops. I totally lost touch with what I was doing. Thank God for the rev limiter. :D

Originally posted by Shobo
I was thinking of gettin cams but my friends told me that using aftermarket in an automatic doesn't do jack.. It is only good for manual....anyone can confirm this??? IM out!

Your friends don't know what they are talking about.

Geo's a monkey!

Purple Monkey Dishwasher.

-Phil

94' Silver P10 G20

yes i think my SR20 is the roller rocker one
JWT is apparently designing a set of cams for us :)


The rev limit is controlled by the ECU and is handled by cutting the fuel. It can be rather dramatic in the SR20.

does this mean that i should probably remap my ecu/ or even change it since my ecu cuts my fuel supply at around 6800rpm...which i really do hate
7850 and 6800 is a huge difference...esp for NA cars where you get your horse power from high reving

Originally posted by pche059
yes i think my SR20 is the roller rocker one
JWT is apparently designing a set of cams for us :)

does this mean that i should probably remap my ecu/ or even change it since my ecu cuts my fuel supply at around 6800rpm...which i really do hate 7850 and 6800 is a huge difference...esp for NA cars where you get your horse power from high reving

I don't blame you for hating the 6800 rpm redline. It's lame. The SR20 loves to rev. I would send an e-mail to JWT and ask if the roller rocker engine can be safely reved to 7850 rpm. If you don't get a reply, let me know and I'll get the correct information to you.

what's their website URL and what's their email address?
:P

Originally posted by pche059
what's their website URL and what's their email address?
:P
http://www.jimwolftechnology.com the email is on the web page.

P10DET : I am not getting any reply from JWT..... so if you could please find out form me it would be grealy appreciated
thx man :)

Originally posted by pche059
P10DET : I am not getting any reply from JWT..... so if you could please find out form me it would be grealy appreciated
thx man :)

You bet.

Give me a little time.

So far JWT has not tested it above the 6900 rpm stock redline.

Hmmm. Sorry to get your hopes up.

A 7850 rpm redline is so cool. :D

haha damn
well thx alot man... gosh you are quick too
hey is it worthwhile to get the cams done on an auto G20?
the kinda gear ratio you have on an auto requires a rather wide powerband to get the car really moving ....am i right?

Originally posted by pche059
haha damn
well thx alot man... gosh you are quick too
hey is it worthwhile to get the cams done on an auto G20?
the kinda gear ratio you have on an auto requires a rather wide powerband to get the car really moving ....am i right?


Well, most of us Yanks like a wide power band anyway. We tend not to rev the engine as much (well, some of us). It's some strange thing with our general population. I guess they think the engine will explode if you rev it above 4k rpm or something. :p

I cannot comment on the cams for your car yet since they are still in testing. I would imagine JWT will come out with a set with a broad power band though. I think they would give the car a good bit more zip, but again, until the testing is done, I can't exactly say.

haha

Well, most of us Yanks like a wide power band anyway. We tend not to rev the engine as much (well, some of us). It's some strange thing with our general population. I guess they think the engine will explode if you rev it above 4k rpm or something.

this is not quite true...I used to drive a 2.2 DOHC VTEC...and man you will pick up a habbit of redline your car after owning one of those.....
the fact that there is still plenty of torque around the 7.2k rpm....

sad that with SR20DE s.... nothing much is left after 6000rpm.....

Originally posted by pche059
sad that with SR20DE s.... nothing much is left after 6000rpm.....


Well.... most SR20DEs. :D

Actually, it's not that hard to make a SR20DE happy at higher revs. The older ones are certainly happier though. Keep working on the breathing....

CAI, cams, and header really bring it to life at higher rpms.

I have got my CAI done already....
am still thinking about the exhaust system...

how would the header and the big bore alter the power curve do you know?
would it extend the power band? to a high rev area or is it just more torque but power band remains?

Originally posted by pche059
I have got my CAI done already....
am still thinking about the exhaust system...

how would the header and the big bore alter the power curve do you know?
would it extend the power band? to a high rev area or is it just more torque but power band remains?



The header (if it's a good one like Hotshot) will give you gains across the board. It should taper off far less at high rpm. Breathing is the issue at high rpm with the SR20. As long as it can breath, it will keep making power up there.

If you mean throttle body when you mention big bore, it will do nothing for power based upon dyno tests by others. It will improve throttle response due to the larger area.

Originally posted by pche059
I have got my CAI done already....
am still thinking about the exhaust system...

how would the header and the big bore alter the power curve do you know?
would it extend the power band? to a high rev area or is it just more torque but power band remains?

I'll assume you mean a big bore exhaust. Be aware that if the exhaust piping is too large in a NA car you may lose power in the lower rpms. This is because the larger pipes can lower the exhaust gas velocity and screw around with the cylinder scavenging effect. Because volumetric flow is lower at lower engine speeds, the exhaust gas velocity can become too slow (if the pipe is too big) to help evacuate the cylinder at the end of the exhaust stroke. If you fit a header, then the critical part becomes the diameter and length of the primary pipes and the collector. I have a link at work that I'll post tomorrow which gives some rough guidelines.

Here's the link for general exhaust pipe sizes.
http://www.isd.net/jhadfiel/exhaustsize.htm

A 2L engine is 122ci (which is off the bottom of the scale on this link) and lets say your gonna make 150-200hp at the flywheel, according to the chart, a 2 1/4" single pipe will be more than adequate. any larger and you'll likely lose bottom end torque, and in extreme cases, high end hp as well. Fitting a well designed header would make this a non issue as the header will bring things back (exhaust gas velocities) to where they should be. In this case you will get no gain from having pipes larger than the final collector on the header.

Also see this post for more cam info http://www.automotiveforums.com/vbulletin/t8026-2.html ;)

Originally posted by T4 Primera
I'll assume you mean a big bore exhaust. Be aware that if the exhaust piping is too large in a NA car you may lose power in the lower rpms. This is because the larger pipes can lower the exhaust gas velocity and screw around with the cylinder scavenging effect. Because volumetric flow is lower at lower engine speeds, the exhaust gas velocity can become too slow (if the pipe is too big) to help evacuate the cylinder at the end of the exhaust stroke.

BINGO!

So many people think that lower backpressure causes you to lose torque, but that's hogwash. Backpressure is never good. But, if you go too big you lose the velocity, just like T4 said. That is bad.

Originally posted by T4 Primera
A 2L engine is 122ci (which is off the bottom of the scale on this link) and lets say your gonna make 150-200hp at the flywheel, according to the chart, a 2 1/4" single pipe will be more than adequate. any larger and you'll likely lose bottom end torque, and in extreme cases, high end hp as well. Fitting a well designed header would make this a non issue as the header will bring things back (exhaust gas velocities) to where they should be. In this case you will get no gain from having pipes larger than the final collector on the header.


Yep. I concur. Anything larger than 2.25" with anything but a fully built engine is not only overkill, but likely to cause a loss of performance. Mandrel bends though please. :D

As for collectors, Mike Kojima has done a fair amount of testing prototype headers for Hotshot and they found that any collector over 2" actually lost power - even on his built engine.

There is a large amount of misinformation about exhaust size still floating around and I think it comes from old school hot rodders of American domestics. On many of them the exhaust is so bad that they almost couldn't do anything to make it worse. That's really sad since most US cars have such a narrower operating range than most European and Japanese engines. IOW, the European and Japanese cars must have exhausts that work well from say 2000 rpm to as much as 8000 rpm and more. The US cars only need to flow from 1500 rpm to about 5000 rpm or even less since most US V-8s breath so poorly anyway near their redline.

hey...from the sound of this...
how about just changing the header and keeping the rest of the exhaust system?
am i still gonna get power gain?
save me money too :)

Originally posted by pche059
hey...from the sound of this...
how about just changing the header and keeping the rest of the exhaust system?
am i still gonna get power gain?
save me money too :)



Yes, you will still gain power. In fact, you will still gain most of your power. The exhaust will only net you an addition 2-3 hp most likely.

I would say, bang for the buck, pound, frank, etc, exhaust is way down the list.