Less Reciprocating Mass...

[mach4g63t]

Need some help with a little more experience than myself and a buddy. I finally got my 'bonus' money from a little side-job that I did. I'm starting to price-check all the stuff I wanna try and lighten up.

First and foremost, is the speed difference in which the motor revs worth doing? Is it even that noticeable? And does it kill the reliability of the motor? When this little project finishes up (hoping early to mid fall ) I wanna be ~350hp, give or take. I still want to daily drive it for the most part.

So far I've read that lighter pistons/rods, flywheel, balancing shaft, and a butchered crank are the best ways to do this. Anyone have any experience with this sort of stuff and got any references/distributors that I can look into for prices and more information? It's on a '95 TSi AWD with ~114k on the motor. It's getting rebuilt though, and this is something I've really interested in having done.

 

[gsxeclipse97]

The flywheel by itself is a large difference in rev speed I would recomend a lighter flywheel but if you go to light the car will stall.

 

[mach4g63t]

Why would that make the engine stall? And if what you're saying is the truth, and with my power goals, which are still low enough to run stock internals, I should just keep the stock rods and pistons? Maybe swap for 1g rods? They're better, right? So, just get a light flywheel and pull the balancing shaft and it should be gravy?

 

[Splitpi]

The car stalls because of the decrease in momentum due to less rotating mass upon engagement of the clutch. But after a bit, you will get used to it.

 

[gsxeclipse97]

you can't use the 1g rods unless you do a 6-bolt swap. the crank shaft on the 2g is bigger than the 1g. you can use the 7-bolt to achieve your goals of 350hp very easy

 

[dsm-onster]

Need some help with a little more experience than myself and a buddy. I finally got my 'bonus' money from a little side-job that I did. I'm starting to price-check all the stuff I wanna try and lighten up.

First and foremost, is the speed difference in which the motor revs worth doing? Is it even that noticeable? And does it kill the reliability of the motor? When this little project finishes up (hoping early to mid fall ) I wanna be ~350hp, give or take. I still want to daily drive it for the most part.

So far I've read that lighter pistons/rods, flywheel, balancing shaft, and a butchered crank are the best ways to do this. Anyone have any experience with this sort of stuff and got any references/distributors that I can look into for prices and more information? It's on a '95 TSi AWD with ~114k on the motor. It's getting rebuilt though, and this is something I've really interested in having done.

So you're telling us (being someone who's put a DSM in the 13s) that you're looking to cut the crank (and/or other material) to lighten the reciprocating assembly! All for 350 hp???!!!!

Get a 16g, bigger intercooler, safc (or eprom chip SINCE YOU HAVE A 1995), bigger fuel pump and injectors. and be done w/ it. You'll have to get this anyway. Even if your cut your assembly weight in half . . . Why even lighten a flywheel when said fly wheel is good for 12s w/ mods you'll need to meet your goals, no matter what the weight of your body or rotating mass?

 

[snox135]

It might stall with a lightweight flywheel. Mine did it a couple times after installing it. But doesn't do it anymore. If the rpms are high and you throw in the clutch it will has a better chance of stalling. If you let the car engine brake some it helps the stalling.

For you power goals the stock engine will do fine. If you are going to rebuild the motor, you might as well get some Scat rods and Wiseco pistons.

 

[Laysher91]

You want less "Rotating" mass. If you had reciprocating mass your engine would shake like crazy. Light weight pulleys would help you out too.

 

[Nanan]

You want less "Rotating" mass. If you had reciprocating mass your engine would shake like crazy. Light weight pulleys would help you out too.

Reciprocating mass = pistons and rods and in some cases the crank if it isn't balanced vs the weight of the said pistons and rods.


Don't worry about stall from low rotating mass, the only time you will even notice it is when the engine is cold.


You don't even need to touch the engine's internals to hit 350 hp but if you do poke around inside a set of cams will help.

If you plan on building an engine just get a 6-bolt to start with, the 7-bolt isn't worth building. Trust me.

 

[dsm-onster]

other than the overrated occurance of crankwalk, what is the problem w/ building a 7-bolt?

Also, I've seen a 7-bolt hand 450 hp. . .

 

[mach4g63t]

Yea, I had a car in the low-13's before. But that's nothing. That was just a MBC, 3 inch exhaust with no cat, some hard pipe, a ported head and manifold, some free mods and a whole lot of stock motor. Truth be told, I've never really broken down through the internals of an engine and I'm planning on getting my hands dirty and learning how . Up until now I've kinda had the whole drive it for kicks mentality, but my wallet can't keep up with that mindset anymore.

I just thought the idea was pretty intriguing as I've read a few things about it here and there. The whole super-fast revving motor just seems/sounds really bad ass. It just seemed like a good idea. That's why I was asking and checking out the input of more knowledgeable people as to whether or not it's worth-while to do before I actually bought parts. I was mistaken about the 1g rods though. Anyway, appreciate the input and stuff. For now, I guess, I'll just stick with the modding list provided on the forums.

 

[90laserRSfwd]

Butchered crank = 7 lbs off www.ffwdconnection.com
Carillo A beam rods (lightest I've found) www.extremepsi.com
Mahle pistons (less then 300 grams!) www.extremepsi.com
ACT streetlite flywheel www.extremepsi.com

Don't forget the BS eliminator kit, ARP main studs. Oh and might I suggest www.kigglyracing.com (check out there stud girrdle, if your doing a 6 bolt swap) WHICH FYI YOU SHOULD BE. Also the carillo's are the lightest steel rods I've found. Aluminum rods work on the street you just have to check them more often, well the bearings and rod bolts @ least. BTW Groden aluminum rods only way like 520 grams and that's about as light as you could ever hope for. I'd say 350whp isn't even worth a rebuild... seriously