hey guys question, i want to run 3.29s as well as a 3k stall torque converter, I'm running an xp cam and the lowest i could get the idle is 1100rpms. way too high and i want the low rumble which it is capable of when idling at 800-850 as well as remove the grabbing when slowing down to lights. does the engine have to be pulled to get to the transmission or can the transmission just be pulled?i know my tranny is on thin ice as I'm running 15psi and over 300whp. thanks zack

 

An L36 transmission has 3.29 gears.

L67s have 2.93.

You can drop the cradle to remove the transmission. I prefer pulling out the engine and transmission all together though. To each their own.

 

Ok 2.93 I had it backwards

 

2.93 gears are slower them 3.29 but 2.93 have more top speed. I prefer 3.29 personally but that's just me. 3k stall is nice. Either gear and convertor will work as long as tuned for it.

I take trans only out the bottom but it's just preference.

You do know gearing and stall convertor don't change the idle right? Idle changes are made in the tune and stress the timing chain more if idle is to low.

 

Yea that I know just want a smoother ride and lower idle so my pistons don't melt quicker than they should

 

Melt pistons by having a higher idle? Never heard of that lol I'm sorry but I have to call bs on that

 

Hope you have a sticky tire setup. The looser converter will get you in the powerband quicker off the line, making it harder to hook up if you have trouble now.

Also keep in mind that with a looser converter, you'll build more heat with the trans. Good time to think about adding a trans cooler

What do you mean that is the lowest you can get it? What happens when you set it lower- say to 1050, 1000, etc? The XP isn't particularly nasty at idle- I would think adding +100 rpm to the stock table should be plenty.

Not sure how accurate this is, but here is a youtube video of a supposed XP cam at 850:


As long as you're tearing into the trans anyways, have you thought about upgrading other hard parts while you're in there? Probably not a bad idea, especially if you want to keep modding.

What is the reason behind going from 3.29 to 2.93? The only thing you really gain by doing that is a little more top speed before hitting the limiter in 3rd. For driving around town, 1/4 mi racing, etc- I think a 3.29 is a better choice.

Melting pistons? Hopefully that was a joke.

As turbo monte said- lower idle is easy and doesn't require any of these mods. It's a simple 2 minute change in the pcm tune. Nothing really wrong with 1100 rpm, but you can certainly go lower. Keep in mind that going super low so it's bucking and stalling is hard on timing chains.

As far as a smoother ride, what specifically are you looking for? Is this the grabbing when slowing down that you mentioned earlier? Sounds like this is likely more of a tuning issue than something that would be fixed with a gear change and converter. Neither of those would really impact deceleration smoothness- that's more in the tune.

 

No it's not a joke , from the shops I've talked to they claim that the higher the idle, the more stress and heat it puts on the engine and combustion chamber, I don't think that's bs. Second when my tuner put the idle at 850 the car kept waking itself up and it would rev up to 1700rpms and go back down to 850-1000. Also the car would shut off half the time. The stock converter is a 500 stall and the 3k would help with drive ability and less grabbing. Would also let the tuner lower the idle to 850 but lowering the idle also puts stress on the timing chain. Also I'm confused what are the stock gears in my 03 l36 transmission. And guys I'm sure I've told you I've gone from one hobby to the next so take it easy I'm new

 

Don't worry about "melting pistons" at idle. Mid-high RPMs is where you need to worry.

Your gears are 3.29.

 

It's not BS that stress and heat are increased, but let's put it into perspective here:

Stress- Idle is pretty much the lowest stress the engine will ever see. The engine is under no load from trying to turn the wheels, and rotating assembly stresses are proportionate to rpm. Where the stresses start to approach the design limits are when you get up to the higher rpm, close to redline. The piston still has to stop at each end of its travel and reverse direction, but due to the drastically increased RPM, the time to change speed decreases, so piston/rod acceleration increases, and stress go up immensely. But we're talking 6000 - 7000+ RPM here, not 1100.

Heat- I guess I can go along with this a little more since you're running maybe 25%+ over stock rpm depending on temperature- so simple theory is that you're adding a proportionate amount more fuel, which also increases the heat being lost into the piston/block/heads which gets dissipated through the radiator. Where this thought falls apart is when you start driving the car. Get on the highway doing 65-70, and now you can drive for hours and hours at 2000+ rpm under load. This would theoretically create double the heat you're making at idle (obviously I'm oversimplifying this though), and yet you don't overheat and melt pistons then.

The thing is your cooling system, if functioning properly, is more than capable of handling a little extra heat at idle. You have fans that will kick on to circulate air when not moving, and that will be plenty sufficient to keep the engine cool.


So to a point, they're right - stress and heat are both increased- but the amounts are so tiny that they don't matter. We're not talking top fuel dragster 3000 rpm idle here, so please don't let this shop scare you into thinking that your engine is going to melt. If they're so convinced, ask them to show you a 3800 that melted at idle. Sure people chunk pistons on 3800s- but that's at wide open throttle with too much heat/boost on an engine that either has maintenance issues or insufficient mods for the boost level. Even the smallest SC pulley on a stock engine isn't going to chunk a piston at idle.

I think there are probably some other issues here, but did he try any other settings in between- say 900, 1000, etc?

That is not true, the stock converter is not a 500 stall. The rating systems are a little hard to A-B compare, but just for comparisons sake, ZZP rates their stock L67 replacement converter at a 2000 stall. Your car, being NA from the factory, should be higher than that.

I don't think a 3k stall is going to help drive ability at all, it's going to be worse. On street tires (ie not on slicks/DRs), the car will be harder to launch because it will get into power quicker at WOT. Also, for regular driving, it's going to be noticeably more sloppy than your stock converter- at least mine was going from a stock L67 converter.


Again, the converter you run doesn't at all dictate idle speed. You could put a 2000 stall in there or a 5000 stall in there, and the car's idle will still be independent of that- all adjusted by the PCM via the IAC valve. It can certainly dictate off idle-drivability as you accelerate away, but talking purely idle with the car stopped- it doesn't make a difference.