By putting a high performance under drive pulley how much hp cant I expect? Will my car over heat do to less rotations going to my water pump?

 

Read to the end of this thread about some under-drive pulleys:
http://web.camaross.com/forums/showthread.php?t=532173

Two people with the same results and both have under-drive pulleys....coincidence???
Maybe.....



Tom Piper

 

If you read the above posts carefully......you will see that the installer actually REMOVED the damper which does not make any sense. Without the damper (it has the timing mark) you could not time the engine and it also is tapped to bolt the pulley to the damper. Without the damper you couldn't install the pulley and have it line up with anything. I think that the installer(s) did not torque the bolts to the damper when installing the under drive pulley.

I have installed March three piece pulleys on my 85 without any problems. The car does not over heat *(although I run a 160 thermostat & the chip is programed to turn on the fan early). I have not had a problem with the charging system either. In fact, it charges better at lower RPMs than the stock set up. Many of the Forum members have them. The only complaints seem to be with the charging system and this is usually tied to a two pulley system.

You will only gain perhaps 5 HP. Go with the three pulley option from March. You can also buy direct from March on their web site and save a couple of dollars.

 

Interesting link. Someone took the dampner off and it cost them an engine?

As far as I know the L98 pulley kits just replace the stock pulleys and you do not touch the dampner.

No you would not over heat with UD pulleys.

The March pulleys are nice:

http://www.marchperf.com/pg10.html

 

I have the under drive crank pulley, overdrive alternator pulley and the AIR removal pulley.

Noticeable difference!!!

 

I installed March Power & Amp 3 piece pulley system in May of this year. No overheating or other problems. March claims 6 to 8 HP with these pulleys. Who knows, but the car does seem to rev a little quicker. I would recommend them. No need to bother the balancer. The crank pulley is a straight bolt on.

 

So if you remove the dampener exactly where do you mount the underdrive pulley to? That is a funny fking thread, and even more funny that someone here posts that crap that an underdrive pulley install caused cam bolts to break.


Now for a non retarded post, my first btw. You will notice a low end torque gain. I did on my cars you will too. Not sure what it gained on the top end but don't expect to pull mountains down with your gain, maybe 15 lb ft tq., maybe 10 hp.

 

Bought a set of API direct (around $150)and they fit up fine and easy fit used them on a 89' and made up my on air pump delete system. No problemswith charging and tempature did change out the water pump to a new edlebrock.
wro87

 

Thanks for all your replies!

 

I didn't realize you had an L98 until I read your signature.
I should have realized it by the water pump comment.


That post is from an LT1/LT4 forum.
The LT1/LT4 does not have any timing marks.

On the LT1/LT4, the stock damper is the pulley -- it is a single unit.
If you remove the stock pulley, you are also removing the damper.
If you remove the stock damper, you are also removing the pulley -- there is no way around it.
I've never used an under-drive pulley on an LT1, but my guess is it has to be a special under-drive/damper combination that bolts to the OEM hub -- or, a complete unit hub/under-drive/damper and all.
I'm also guessing that these two people somehow figured out how to put a L98 pulley on an LT1 after removing the damper/pulley combo -- but I don't know that.

I can't think of a single reason why I care what you think.

Tom Piper

 

Edit:
This particular post, in this thread, is probably not of any interest to L98 owners -- it is about the LT1/LT4.
Since that LT1 thread is already linked to this thread, this post is an explanation of what I see in the thread I linked from the F-body forum above.


When I read that F-body post, this is what I think.

The fact that it was a unwise thing to leave the damper off completely is nothing but a short "blip" on the radar screen -- it happened, and that thought is gone.

What can I learn from it?

Well...if it only happened to one person, I wouldn't think much else.
But, if the posts are to be believed, it happened to two people.
And, according to the posts, the results were the same -- so, it probably isn't an isolated incident.
And, it must not be hard to accomplish -- even though I can't figure out how they did it -- once again, a fleeting microsecond thought.

Now, to me, the meat:
Leaving the damper off completely is an extreme, but it does seem to indicate that torsional vibration can be more damaging than I thought.
The one person stated that his car was completely stock except for the under-drive pulley -- that would seem to indicate that it was rev-limited at about 5800 rpm. And, the damage happened in a few thousand miles.

My next thought is: what would happen to a vehicle with an inadequate damper? -- maybe a vehicle that reved much higher and possibly the stock damper just wasn't up to the job. After all, GM thought the stock LT1 damper wasn't up to the job for the LT4 since they put a dual-mass damper on the LT4 instead of using the LT1 single mass damper and the LT4 only spins to 6400 -- not a big difference. Plus, GM wouldn't spend 2 cents if they thought they could get by without it (witness the lack of key in the LT1/LT4 crankshaft hub).

Then, another thought is about the water pump drive gear being chewed off (shredded). Very interesting is that this happened without the Extreme Duty Timing Set.
The only other times I have heard of that happening is when people with LT1/LT4 engines used the Extreme Duty Timing set -- and, that has happened to quite a few on both the Corvette Forum and the F-body forum.
So, this makes me wonder if the problem, when using the Extreme Duty Timing Set, isn't torsional vibration too. Plus, maybe the solution for the Extreme Duty Timing Set is to use a better damper.
Possibly, the Exteme Duty Timing Set, being more rigid, transfers the crankshaft torsional vibration to the camshaft more readily.

That's my thoughts, your mileage may vary.


Tom Piper

 

Seems to me these threads would make a lot more sense IF:
1) posters would ID their cars
2) responders would check the posters profile before answering

My .02

 

I agree, and I am guilty of not checking.

However, not all people id the vehicle in their profile.

 

Another option would be that people were less critical of each other and didn't make rude comments.

As for the UD pulley. It will give slight gain. Nothing major. The real question is is worth the time and effort?

 

An even better option would be to do as the F-Body forum has it:
L98 is one forum and LT1/Lt4 is another forum.
But, that would probably be a lot of work, since a lot of the C4 bodies and chassis parts are the same.

Tom Piper

 

On the L98 it's only three bolts isn't it? Or two bolts with a two pulley system. Or one bolt for just the crank pulley. Couldn't get easier for the gain.

 

On the L98, at least mine, It's 4 bolts on the crank pulley and on my Z51 they are a BITCH to get a socket on because of the crossmember. 90% of my time was spent on those bolts. I wouldn't do it without doing all 3 pulleys. Also I did the aluminum pulleys, except the alternator which is billet steel.

 

I was going to order that kit to, it's $100 more for an AL alt pulley! Summit is showing 9/4 to ship though.

On mine I only remember the one bolt, I used it to turn the engine over when I adjusted the rockers.

Did you find there was a good HP gain?

 

IIRC there is a 5/8's center bolt and 3 smaller perimeter bolts. It seems to spin up faster. I had Thunder drop ship my set direct from March. $151.00 shipped for the P&A alum set.

 

What's the point of doing all three pulleys? Just changing the crank pulley will slow everything down. Unless you feel the need to slow the alternator down further, or just don't want to buy a new belt, I'm perplexed why the desire to spend all that money and time to swap the extra pulleys.