The old 'too light rotating assembly for street' debate

[project_tsi]

I'll hit Luda up for the information.

Does anyone know if DSM Link allows an adjustment for the problem that some are experiencing with light RA's?

Yes it does. DSMLink has great features allowing great idle control. As long as you are boost leak free, DSMLink will do all the work w/ adjusting idle speed. Theres really no need to adjust you BISS anymore, as long as its in good working order, first set the BISS to where you want the car to idle, like 7 or 800, and then adjust further using DSMLink. From the click of the mouse button you can watch and hear the car idle from 700 up to 1100 r's.

 

[Injected]

Thanks for all the information guys.

 

[Ludachris]

There were some references to my idle problem a while back. I need to find that thread and update it. It seems I had a couple things working against me. For one, the ISC was indeed not working properly. It tested fine but after swapping in another one the idle problem was solved (without pushing the clutch in).

Also, when I put my rebuilt tranny back in I put in a new clutch fork ball too. Problem was, I also put the washer back in that I had in there to compensate for the old worn ball. It was extending the fork too much and seemed to be putting added stress on the flywheel when I pushed the clutch in. I'm guessing that helped bring down the revs enough to where the car would stall when I pushed in the clutch. I removed the washer and double-checked that the clutch fork was moving the way it was supposed to when putting it all back together. I believe those two things were the cause of my headaches. The car runs fine now.

 

[jott5555]

I read through most of this and didnt see a whole lot of mention of a crank scraper... i put one on w/ a stock fly wheel ( i know wiht my setup wtf is the matter w/ me) but i noticed a faster rev over a stock engine but that could also be due to a rod/pistin setup..

 

[pneumo]

I weighed my Wiseco piston/ Eagle rod combo compared to the stock 6 bolt pistons/rods and it saves a total of 20 ounces using 9.0 compression pistons. 8.3 compression Wisecos will save another ounce. The new Mahle pistons also look light.

Like Ludachris said, it's not always the light flywheel that causes stalling. It could also be a combination of mods that are great for top end power, but hurt idle, like big cams, high capacity airflow sensors, big injectors and trying to use a base idle speed that's too low. So raise the idle. Coincidentally, raising the idle will also make it easier to pull away from a stop for daily driver use. Like you said in the first post, a lightened RA has less kinetic energy stored in it so you need more revs to get off the line smoothly.

 

[pneumo]

This thread inspired me to take a deeper look into the stock ecu code, so with the aid of one of the members on the DSM-ECU list I was able to identify a few areas of code that could be changed to keep a car from stalling. Yes, that's right, we now have Lightweight Flywheel Code!

Essentially the code does 3 things; raises the idle speed, raises the idle on/off threshold so the idle circuit kicks in sooner as the engine rpm's fall, and raises the moving idle speed so when the car is moving the target idle speed is even higher. I tested this code in my car and it works great, hasn't stalled yet, and I tried hard to make it stall. The test car was my Talon, which has a very light RA with a Fidanza flywheel, underdrive pulley, no AC, no PS, no balance shafts, Eagle rods, and Wiseco pistons. My car also idles bad from cams timed for high rpm power and an extremely hacked maf, and it doesn't stall anymore.

If you want to try out the code contact your favorite eprom programmer.

 

[d j]

slightly off topic...

FFWD Connection, who is making quite a name for themselves, sells their almost-world-famous "butcherized" cranks, about which they say "As if that was not enough, and feeling a little sassy, we lighten the crank by 7 pounds which results in even quicker revs and increased horsepower by eliminating that extra rotating weight. Now, I know what you're thinking but don't sweat it...our lightening procedure does NOT hinder its reliability nor its function. In other words, GO POUND ON IT! Couple that with an aluminum flywheel and rods, and you're talking about a motor that will rev as quickly as a crotch rocket."

I can say this (because i'm local) and have seen with my own eyes... those cranks are of someone elses work (BJ's Cylinder Head) which was a little over 6 years or more ago. I can't recall anyone having a r/a that was too light or weak (even on groden rods). I've got no idea about FFWD/Darren's ability to cut & knife cranks... But I can say BJ is where he got 'em from when FFWD/Darren's site went up.

If you look now.. BJ's stage 5 heads (6+ years ago technology) are still for sale on ffwd's page :]