Problems with slip and new idler pulley, any thoughts??

[Daryl B]

Ok, so here is my problem. I purchased the BilletFlow idler pulley to eliminate my belt slippage. Very quality part and installed very easy. Thanks to Doug for another great product and regardless of my results, this product clearly is a tremendous improvement in belt wrap.

Every post I have seen says this part eliminated their slippage but I have a different experience. I have a 2.80 upper and no lower. The first belt I tried was a gatorback 73.5 which took up all the adjustment on the tensioner. I couldn't wait to try out my car with my new part. I ran the car hard in several gears and at 5000 RPM's my boost starts to fall and by the time I am to 6000 RPM's the boost is barely holding at 10 (around 13 before 5K). I thought maybe my belt might be the problem since it had been on and slipping for about 1K miles so I replaced it with a slightly longer Gatorback (the tensioner is now in the middle). The results were the same. I wiped clean all the areas around the upper pulley and made a few high RPM runs, with both belts there was new belt residue.

Doug at BilletFlow was nice enough to call me on Saturday when he heard about my problem but he insists I am the only person with this problem. He said he spoke to Rick @ Amazon and he was running a 2.70 upper with absolutely no slippage (I think he also said Rick had a lower on as well but don't quote me).

I am hoping some of the experts here might be able to suggest some possibilities as to why I am the only person with slippage. I can see how there might be very minor belt slippage but there should not be enough to loose 3lbs, should there? Is there something else that could account for the loss of boost at high rpm's (overspining, altitude……..)?

Thank you in advance for taking the time to share your thoughts.

 

[03DOHC]

Maybe your tensioner is weak?

 

[08snake]

Originally posted by 03DOHC
Maybe your tensioner is weak?

Yep. Got to be another pulley or tensioner. That belt wrap just seems too good to allow belt slippage on the upper IMO.

 

[Rick@Amazon]

Right now I'm only running a 2.70 upper with the 95mm steel idler with no slip. I'm running a gates k080745 which is a 74.5" belt. Your belt is 1" shorter then mine. Did you snap the stop off you tensioner?

Rick

 

[BlownCobra]

Could it just be that you’re over spinning the blower???

NO FLAMES please. I know this thought is not a popular one. It squashes hope for the would-be weekend racer looking for more... While removing the ability for the distributor/manufacturer to sell us another product.

Many believe that after a certain point the blower is done. Several of the best professional tuners/installers in NY, NJ, MI, TX and CA. will no longer advise there customers to install idler pulleys, or new belt wrap devices because even though they work very well, belt slip is not your problem. We are finding even if you run a 6# lower with a stock top blower pulley you will make boost that will drop off after 5000 rpm. My own experience in testing a 6# lower only, 13.5 to 5000rpm, then drop off to 12.

This is my opinion.

There are guys getting 15 and 16 #'s and claim they have no drop off. I have not seen this. I have tried several combinations. i.e. 4# lower 3.10 upper, 2.80 upper only, 2# with a 2.80 upper, 2.93 upper only. I have used the 100mm idlers and the belt wrap device. Lost boost after 5000rpm every time.

There is a belief that the QUD cars have a blower with better tolerances. I don't know if that is true, I have been unable to prove it.

Also, how did you get a 73.5 belt on with a belt wrap device?

 

[dougwg]

Originally posted by Daryl B
Doug at BilletFlow was nice enough to call me on Saturday when he heard about my problem but he insists I am the only person with this problem. He said he spoke to Rick @ Amazon and he was running a 2.70 upper with absolutely no slippage (I think he also said Rick had a lower on as well but don't quote me).

just to clearify

Maybe I wasn't clear.

You told me you were still getting BELT SLIP, that is when I said your the ONLY person that I have heard of that installed our idler pulley and bracket and is still seeing belt slip. We both agreed that the belt you were using could be “glazed over”, which is when I suggested trying a NEW belt.

As far as BOOST DROP, which is a totally different problem altogether.... well your gunna have to talk with someone other then me who is more knowledgeable on this subject

I’m sorry that I couldn’t have been more help.

Doug
BilletFlow

 

[BlownCobra]

Re: Re: Problems with slip and new idler pulley, any thoughts??

Originally posted by dougwg
just to clearify

Maybe I wasn't clear.

You told me you were still getting BELT SLIP, that is when I said your the ONLY person that I have heard of that installed our idler pulley and bracket and is still seeing belt slip. We both agreed that the belt you were using could be “glazed over”, which is when I suggested trying a NEW belt.

As far as BOOST DROP, which is a totally different problem altogether.... well your gunna have to talk with someone other then me who is more knowledgeable on this subject

I’m sorry that I couldn’t have been more help.

Doug
BilletFlow

Glad you mentioned that Doug. You see there is a common believe that "Boost Drop off" is associated with "Belt Slip" I was trying to distinguish between the two in my post, about "overspinning the blower" for Dayrl B, and many others who have this believe.

 

[slythetove]

I also get the feeling that many people are confusing "boost drop" with "belt slip".

Don't you think that at some point in the upper RPMs pressures equalize and boost SHOULD be dropped again? I do. Seems like expecting full boost at anything greater than 10 / 11 all the way to redline is a bit wishful.

I could be wrong, but as I understand the way boost comes on under load.... eliminating that load differential and vacuum should, at high RPMs, equalize and dump some boost.

Anyone else?


EDIT: Here's another more technical group than myself explaining the same thing:

http://www.modularfords.com/forums/showthread.php?s=&threadid=979

 

[BlownCobra]

Interesting reading,

Do you think the "Boost bypass mod" and/or "dump mod" work in holding boost past the 5000rpm mark without bleed off?

 

[Daryl B]

Originally posted by 03DOHC
Maybe your tensioner is weak?

The tensioner was the first thing I thought of, but it is fine. Thanks for the response.

 

[Daryl B]

Originally posted by AmazonRacing
Right now I'm only running a 2.70 upper with the 95mm steel idler with no slip. I'm running a gates k080745 which is a 74.5" belt. Your belt is 1" shorter then mine. Did you snap the stop off you tensioner?

Rick

No I did not snap the stop off, but putting the belt on was next to impossible. The shop I bought it form, said to use the same belt as what I was using. I questioned him about needing a longer one but he said no (I did try to buy from you first but never got a response to the Email). So I installed the new puller at work and realized the belt was too short but I had to get home so I forced it on. I now have the 74.5" on. Thanks for the response Rick.

 

[Daryl B]

Re: Re: Problems with slip and new idler pulley, any thoughts??

Originally posted by dougwg
just to clearify

Maybe I wasn't clear.

You told me you were still getting BELT SLIP, that is when I said your the ONLY person that I have heard of that installed our idler pulley and bracket and is still seeing belt slip. We both agreed that the belt you were using could be “glazed over”, which is when I suggested trying a NEW belt.

As far as BOOST DROP, which is a totally different problem altogether.... well your gunna have to talk with someone other then me who is more knowledgeable on this subject

I’m sorry that I couldn’t have been more help.

Doug
BilletFlow

Doug,

The reason I checked for belt slip is becasue I had hoped a tighter wrap would help with my boost drop but it didn't seem to help at all. If the residue around the pulley and snout is an indication of belt slip than I still have some.

My post might have come off the wrong way. I think your product is tremendous. I think your cunstomer service (ie. callling me on a Saturday) is second to none. I would recommend this to anyone because it clearly gives you a better wrap. I did try a new belt before I posted my thread. I am just trying to figure out if there is something else I should try. Thank you again for your help.

BlownCobra---Thanks for the response. I do know there is a difference between boost drop and slip. I did not realize a 2.80 pulley would drop that much above 5000 RPM's. I just assumed a better wrap would help keep some of the boost up. Clearly there is a limit to how fast you can spin these blower.

 

[SVT 03 Cobra]

I also run a 2.80 upper and no lower... 74.5 gaterback... 0 belt slip... the boost loss after 5000 rpm's is the dump valve opening slightly... if you want to avoid this do the valve mod...

 

[dougwg]

Re: Re: Re: Problems with slip and new idler pulley, any thoughts??

Originally posted by Daryl B
My post might have come off the wrong way.

No, not at all. I just felt it needed to be clear as to what I said .... thats all.... no biggie;-)

You have a valid question. Which, like I said, I am not the best person to answer questions about "boost loss". :shrug:

I think you should talk to Rick or Pete.

P.S. has J69gordon answered your question? (dump valve mod)

I feel your pain,,,,,, damn that boost loss, damn it all to hell!!! :-D

 

[Jim Vaccaro]

On the dyno they all see less boost and it drops sooner then under load on the street.
Under load in 4th or 5th you will see higher boost levels and you will hold boost longer.
Running hard in 4th gear you will see max boost from 3000 RPM's up..But at 6000 in 4th going 130 MPH it's hard to look at boost gauge.
We made dyno pull in 5th and a car with 15lbs held boost longer then it did in 4th gear on the dyno..
In every case the boost dropped 3lbs and with less load it dropped sooner.
This all had nothing to do with belt slippage.
The idler can stop belt slippage but it can't make a 13lb Blower hold 16+ lbs of boost..

jim v.

 

[jtfx6552]

Originally posted by J69gordon
I also run a 2.80 upper and no lower... 73.5 gaterback... 0 belt slip... the boost loss after 5000 rpm's is the dump valve opening slightly... if you want to avoid this do the valve mod...

I keep seeing people post about this. No flame, but can someone explain it to me?

I had boost drop from day one. One of the first things I did was check out how this valve works. The valve is normally closed, as in when the car is off, the boost bypass valve is against a stop on the blower, in the position that prevents bypass. When the car is started the valve opens to the bypass position.
When under load, the valve closes again against the stop allowing boost to build. I videotaped my boost bypass valve while doing a dyno pull. The valve lever went agains the "stop" and stayed there until we shut it down.

If the valve is closed against a stop, and stays there, as mine does, how can that situation be improved?

JT

 

[BlownCobra]

Hey JT,
My feelings exactly. I watched Joe's car (MustangMagic) on the dyno. I witnessed the lever going to the stop, and then never moving until the run was over. The valve was functioning properly. What am I missing?

 

[03DarkShadow]

I experimented w/ all sorts of set-ups w/ idlers since i have a few sittin around, the best i got was i replaced the 90mm upper idler w/ a 100mm one and stayed w/ the stock lowers. It was 70 degrees out today. I test drove it boost reached around 12-12.5 psi and only dropped to 11.5 by redline. I didnt like set-up(because the belt was running a lil off the back edge of the idler, the 100mm idlers are a lil smaller) so i changed around idlers. I am currently running the 90mm upper(billetFlow) and 100mm idlers below. I test drove again tonight, granted its a lil cooler, but boost didnt drop AT ALL. stayed around 13.5 psi all the way to redline. I ran it hard several times to see if anything changed. It stayed that way everytime.

 

[BlownCobra]

Hey 03DarkShadow

Glad you solved your problem, but I have one question... For a 2.80 upper isn't 13.5 boost on the low side? I am not throwing rocks here but eveybodys post's that I have read with a 2.80 upper make 15+ #'s until drop off.

By you getting 13.5 max, this confirms what Jimmy V just said, you can't make a 13# blower hold 16#'s of boost.

Anyway you did not tamper with the valve to get you steady boost rate.

 

[larryc7777]

I have been following the many "boost drop & belt slip" threads since they starting appearing. Here's what I have sifted out of the wealth of information that has been shared on this subject.

The Eaton 112 is good for about 13-13.5 reliable psi(over 6000 RPM).
Boost drop and belt slip are 2 entirely different animals.
SC internal heat is a major factor in producing & holding boost.
Air restrictions "ahead" of the SC impact boost output.
There is a definite relationship between SC speed & SC efficiency.
Incoming air temperature is a big factor in producing boost.


Some of these factors are interdependant upon each other. And, what might cure 1 problem won't necessarily be a magical cureall. For instance, the idler bracket that BilletFlow produces will eliminate belt slip in just about all applications, BUT that isn't to say that it will cure boost drop too. If you were to combine a good quality CAI, aftermarket TB & inlet tube, and upgraded intercooler capacity, then you would probably be able to "keep" more boost for a longer time. Will this cure all boost drop & allow a solid 20 psi till redline?, probably not.
Most of us are trying to get the Eaton to give us 60-100% more output than the factory had in mind. Granted that the SC has a "safety margin" that will allow for SOME additional boost, but at some point you have to hit the efficiency peak & start the downward slid. Turbochargers have it, too.

The reason that the newer twin screw SCs can outperform roots style SCs is that the twin screws are MORE EFFICIENT. 1 full rotation of the SC puts more air into the engine AND at a lower temp. Add the fact that the KB unit is a "larger" capacity(140 ci) and you can see why they make more boost & more power.

Is our Eaton junk? Not by any stretch of the imagination! It just wasn't designed to supply the kind of psi levels that we are trying to get out of it. I'm not saying that it can't supply a solid 16-20 psi without boost loss, I'm saying that you have to address other issues & related systems in order to KEEP the boost you produce.