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Posted by snipe99999, Jun 4, 2002
Bolt-on Tech - 4G63 intake, exhaust, intake manifold, ignition, fuel system, cooling, etc.
When they fail they can take out your timing belt causing thousands of $$$ in damage
So that is not something that one should ignore. Many people change them as PM.
I would advise to stay away from solid underdrive pulleys, as they get rid of harmonic balancer feature. You will not damage your engine from that thing separating (it is all one piece), but you could damage your motor bearings
So ether go with new factory until (which will need to be replaced in another 5-10 years) or if you can afford, BR makes an underdrive pulley with fluid damper build in.
Just my $.02...
Hey dude where abouts in Asheville do you live? I live here in Enka-candler. It's good to see someone that's into DSM's, that lives near by. Anthony
Anthony, I'm in north Asheville, near The Hop on Merrimon.
That's cool man, maybe we could hook up sometime and share some lies ! On a side note... I have an ASP crank pulley, billet aluminum, It's suppose to add about 10whp.
>bottom end balanced. I would think that that would put more strain on
>the engine (as far as balance issues go) than replacing the harmonic ?>balancer with an underdrive pulley.
That is a very ignorant statement... We can argue all we want about merits of harmonic dampers but here are some basic engine FACTS:
# 1 balance shaft have nothing to do with engine balance in a sense that we are talking about them, they cancel out inherent vibration in 4 cylinder inline engines (notice now V engines never have balance shaft, but they have "harmonic balancers")
# 2 "Harmonic Balancer" has nothing to do with balance... Its real name is harmonic damper and many people mistakenly call them balancers...
Using both of those when talking about balancing bottom end (something that is done in a machine shop prior to engine assembly) is not correct.
These are very common mistakes for normal people to make. But what is scary is that companies who manufacture solid underdrive pulley use the same incorrect arguments. Showing that they are ether:
- clueless, or
Ether way, that does not speak well of them...
IMHO, solid underdrive pulley might be worth the risk on 150 NT motors (like found in Hondas). Where ~5 hp that you get from one of those pulleys (that is more real number that I saw in the mags), is more noticeable because it is ~4% of power. Put the same pulley on a 400hp DSM motor and you will never notice those extra 5 horses
Sounds good. Send me an e-mail. There's another guy in Asheville with a VR-4. We met recently and "shared some lies."
As for solid underdrive pulley. Opinions vary a lot. There are several top DSM tuners who have noticed strange bearing wear when using those pulleys. The problem went away when they switch to a pulley with a damper. But there are also a lot of people who are using them and everything seems to be OK.
As much as I dislike those things, I can not say that if you use them you will destroy your engine. But why risk it? Turbo DSMs can make a LOT of power. What is 5hp going to do? I have tried underdrive pulley on high 11 sec car and made some back to back runs (with and without it). I could not notice any difference...
I guess everyone should decide if this is worth the risk in THEIR own car. The problem is that companies who sell those things do tell owners the full truth about them. So, many people install them on their daily drivers, thinking that they are totally benign. Which I do not believe that they are...
Hmmm... that's strange because I have before me an old turbo mag where they dyno'd a 1g turbo eclipse with an unorthodox pulley and they pulled 10.1 hp at the wheels. Which at the crank translates into around 15 hp. They said it was a great mod for the money.
> dyno'd a 1g turbo eclipse with an unorthodox pulley and they pulled
>10.1 hp at the wheels.
Yes, I remember that Project Talon, which read like what NOT to do on a DSM
As I recall they also quoted a manufacturer of that pulley as saying that this is not a harmonic damper but rather a accessory belt damper. If you read DSM Technical manual, it clearly state that it is there dampen harmonics out of the crankshaft.
They were blindly following what the manufacturer (who puts a lot of adds in EVERY Turbo Magazine) told them. Turbo Magazine lost of a lot credibility in my eyes after that article. It was one thing putting stupid mods on their Talon (there is some merit in being original). It is another story when you kiss sponsors a$$ and repeat marketing BS, which I am sure, they knew was wrong
>Which at the crank translates into around 15 hp. They said it was a great mod for the money.
I have seen other tests yielding 4-5 hp at the wheels
And I also know what I have experienced first hand.
I understand where your coming from, and I appreciate your advice on not using a crank pulley. For each his own, I guess. I have a "2g" so my crank is prone to walk anyways whether I use a pulley or not. I'm prepared for that, so I guess I will take a chance on one. 4-5 hp at the wheels is still about 10 hp at the crank. In comparison I paid $80 bucks for my pulley. I also paid around $80 bucks for my K&N fipk, which in return makes about as much power as the pulley does, so I don't see any problem with just 4-5 whp if that's all that's gained. I think if I'm not mistaken DSM performance had the whole 2g unorthodox kit installed on a 2g, with no other mods, and did a test on there car and knocked about 4-5 tenths off there previous 1/4 time. They showed the timeslip on there web site awhile back to prove it. Later!!!
I asked them once about them about the pulleys They said that typical gains they see are .2-.5 tenths off 1/4 mile times. Most of the numbers are off lightly modded cars. They ALSO recommend that you have the motor balanced. That is not really something most people do. I guess it is just a risk to take if you want. It is just like modding any car. If I put on a bigger turbo and try to tune the car for more power. Is there a risk with that Hell Yeah!! But there can be more power to have.
I stand corrected on the modded part, my bad. I would still take that .2-.5 tenths anyday, even it being a lightly modded car. Power gained is power gained. That's what were all after, at least I think it is, anyway. Later!!
1) Stock 7-bolt with a failed crank pulley. No signs of crankwalk. I throw on an underdrive pulley. Literally 5 miles later, bye bye crank sensor.
2) Replacement Magnus Motorsports built balanced 6-bolt block assembly. Underdrive pulley still on. after 6k miles, it wears through the thrust bearing again.
3) Replaced my crank with a new balanced crank. Removed the underdrive pulley and add a stock factory pulley. No other changes. Same install thrust bearing precautions as the last install. Measured play last weekend at .005 from the original .003. This is after 2500 miles.
I will leave you to decide but as far as I am concerned, an undampened pulley will NEVER go on any motor I run or build. Period.
>typical gains they see are .2-.5 tenths off 1/4 mile times.
Let give them the benefit of the doubt and say that they are making 10-15 extra hp. How do you pick up ½ a second ¼ mile ET improvement out of it?
There are some simple laws if physics that are being violated there
Thanks for the post. What happened to you is definitely worth considering, especially on the new balanced 6 bolt. That's the kind of feedback I was talking about.
Also the suspension really clunks over bumps...sounds like its gonna break off. The car is not lowered either.