NGC + Mods - Let's Talk

Post by **Canada** » Tue Mar 05, 2013 10:53 am

So, I've been doing some searching and there's been lots of guesses, assumptions and suppositions in regards to NGC and some modding...

It's fairly safe to assume that basic mods like CBE, CAI, etc don't have any negative effects, and people like Jerome Adams have tried to go a little further and hit limp mode when running a 60mm TB once they go more mods like P&P head, etc...

Has anyone tried running a larger cam (Crane 14 for example) with the NGC R/T pcm? I know the programming for an RT is going to be different from say an SXT and I'm curious to see what happens.

Here's what I am thinking of trying on an '03 SXT: P&P CNC SOHC head, Crane springs and retainers, OS valves, Crane 14 and adjustable cam gear (Maybe advanced a degree / degree and a half?). Functioning Mag IM using RT PCM and engine bay harness. Stock low mileage 2.0 NGC block and I'll pull the shim from the MLS gasket. Stock TB with Volant CAI (whale penis), Either Mag exhaust manifold with catless DP and defouler (or something else? suggestions?) or some variety of LTH.

Ideas, Suggestions, Theories welcome.

D-Railed_Neon · Post by **D-Railed_Neon** » Tue Mar 05, 2013 1:12 pm

Hey man. I bought Jerome's car off him and am driving it now. According to him he was able to run the 60mm without hitting limp mode before he swapped to the ported mag head and comp 400 cam. My car is running the stock 03 sxt pcm and engine harness. Mag intake is controlled by a mad window switch. The car runs limp mode free with a ported mag head, comp 400, UDP, adjustable cam gear, obx long tube, aem cai, cat back exhaust, and the stock TB. The car pulls really hard at 4k plus but under 3k runs about the same as my old 02 did with the slightly higher compression. I too am curious about a magnum PCM and engine harness. I would like to be able to take advantage of higher octane and more timing advancethat's the Magnum PCM offers to squeeze a little more power out of this bad girl. Check my project blog for a full list of mods and pics of the car. I plan on going boost with megasquirt and will be running oversized valves for that but I am curious as to whether a stock PCM will handle oversized valves correctly or not

Hope that helps man

Post by **occasional demons** » Tue Mar 05, 2013 3:11 pm

The OS valves shouldn't have any more effect than a little more lift/duration on the cam. From what I've read, they don't make a huge gain anyways.

Not like the 340 heads vs the 318 heads, back in the day. The intake valves increased .240" in size from 1.78" to 2.02" vs the .0393" for neon OS valves. Proportionately, the size increase was still more on the small block head. (I considered the fact that there are two vs one in my guestimate)

Would I install them if I had the chance? Sure.

As long as manifold vacuum is not drastically affected, which it shouldn't be, the stock PCM will do just fine with them.

But they do work nice for fixing sunken valves.

I'm wondering if any one has installed one OS on the intake and one on the exhaust, diagonally, to try to get more of a swirl effect?

Post by **Canada** » Tue Mar 05, 2013 3:46 pm

Thoughts on the larger cam though Bill? My understanding is that the 14 less vac so the PCM thinks there is a load and adds fuel, which negatively affects the idle? Isn't that what causes the lope anyway? What's the big deal, if it's only at idle, that's not the end of the world correct?

D-Railed_Neon · Post by **D-Railed_Neon** » Tue Mar 05, 2013 11:27 pm

OD if you haz the facebook we have a pretty big discussion on the matter and I know I would like to hear your thoughts, dante and ericks too. Sure a lot of guys have been waiting for a good chat on it. Thanks for bringing the topic up Canada

Post by **racer12306** » Wed Mar 06, 2013 7:04 am

Facebook sucks. Bring it here.

Post by **Canada** » Wed Mar 06, 2013 8:12 am

That's why I posted it here, and linked it on Facebook so people could join the convo... I'm interested to see what Holmes and Erik have to say.

INVUJerry · Post by **INVUJerry** » Wed Mar 06, 2013 5:45 pm

Canada wrote:Thoughts on the larger cam though Bill? My understanding is that the 14 less vac so the PCM thinks there is a load and adds fuel, which negatively affects the idle? Isn't that what causes the lope anyway? What's the big deal, if it's only at idle, that's not the end of the world correct?

Won't negatively effect the idle, but will cause it to idle rich, rich enough to wash down your cylinder walls, and trip a CEL.

D-Railed_Neon · Post by **D-Railed_Neon** » Wed Mar 06, 2013 10:43 pm

well how far off are the comp 400 and the 14? I have looked at the sohc comparisons a couple times but, its pretty comparable if I remember correctly, right? I know the cam I have advanced 2 degrees has the tiniest amount of lope. a little inconsistent and not a full blown diesel effect but a small bit of a stutter. At idle I can SMELL that I am rich as hell but, it is not terrible. With the UDP you can physically see the surges in my dome light and instrument cluster. Not enough to effect my driving lights though
I am not sure but I would think a 14 dialed slightly retarded would be about the same at idle.....I aint gots no CEL for that....

tominator · Post by **tominator** » Tue Apr 02, 2013 9:12 pm

I ran my r/t 04 with comp 400, 60 tb, modern mid-tube header, cold air, udp, shaved head 0.015 etc for 3 years... never had any codes, gaz milleage wasn't bad, but he car really needed some kind of tuning device. The best I could get out of it was 15,9 in the quarter.

Post by **occasional demons** » Tue Apr 02, 2013 11:19 pm

D-Railed_Neon wrote:well how far off are the comp 400 and the 14?

The difference? Valve overlap. There is where the low manifold vacuum comes in. With the 14, the MAP reads a higher manifold pressure, thus tells the PCM there is a load on the engine. So it dumps more fuel. Cam timing will not change that. You have to lean it at idle, to keep it from flooding.

Then there is the fact that the valve overlap lets unburned fuel go out the exhaust valve from the scavenging effect, that all cams with less duration than the 14 do not have, as the intake valve is shut well before the exhaust opens.

The unburnt fuel is going to have a negative effect on catalytic converter life. Thus why all factory cams are zero overlap profiles.

Plus to some extent there is a contradicting message to what the MAP is telling the PCM. The MAP is telling it to add fuel, the o2 is telling it that it is too rich.

And yeah, I don't do FB.