How much noise have you experienced with SC cog drive?
I am running a 72 tooth drive, with a 37 tooth blower pulley with the Goodyear polychain. I would suspect that the noise is from the air being squeezed from between the teeth and the belt.
As a side note, no more excess tension on the serpentine, and I am gauranteed no slippage.
For those who have been here (TJWONG, Bruce, etc.) please advise.
Re: How much noise have you experienced with SC cog drive? (AKS Racing)
Aaron my car sounds like a real gilmer belt. It whines real loud. I have a spring loaded tensioner that applies tension to the belt and it does have a whine to it, very much like a 8-71 blower does. I got a small video but its 4mb :(
Re: How much noise have you experienced with SC cog drive? (tjwong)
Take Toms word, his car has a VERY distinct sound. Very cool sounding, but also very noticeable. Tom, you have no chance of hiding the fact that you have blower, unless the cars not running. :D
Re: How much noise have you experienced with SC cog drive? (ANTI VENOM)
The T Trim is going in this winter sometime. I don't know if the T trim is any quieter as far as the compressor is concerned I just built a new 8 rib pulley and redesigned the Vortec mounting bracket so that I won't have to remove the blower to replace the belt anymore as well. But I am worried that a 8 Rib system would slip. I wanted to test it on my car, with modest boost levels to see how it would react. The way I have it designed the blower pulley has about 320 degrees of wrap around it. I got a guy hot after a 8 rib system here in Portland cuz he don't like the gilmer whine for a daily driver. How are things going up your way? You guys get a lot of snow up that way?
Re: How much noise have you experienced with SC cog drive? (tjwong)
TJWONG,
I went the screw/jackbolt design on the tensioner. You don't need a whole lot of tension with the cog drive (occasional adjustment as the belt stretches). Are you running the Polychain? I do not think that my belt drive noise is quite what you describe, but is has a noticeble whine (different than the normal blower drive) with the hood up. With the hood down, the whole car is noisy, you can not distinctively hear the belt drive over the blower or exhaust.
Are you running guides on your cogged pulleys? I have guides on everything except the crank, but it would take a lot of effort to walk it over the Fluidampner or over the serpentine drive.
What toothed arrangement are you running? Are you right at the limit of the max impellor speed? How much boost are you seeing max? I have 4000 RPM in engeneering design safety (per ATI) on the max impellor speed that I will consume if I ever overshift by 550 RPM. With the old serpentine drive, I think I was only at ~65% max impellor speed. I will now be very near 100% at redline.
The old unit would pull 14 psi, and I have already purchased the 3 bar map for FAST. I have not pulled any data, but I would feel certain that I will be well past the 2 bar capabilities. More tuning to come.
As for the 8 rib, I have been this route, and that is why I am pursuing a cogged design, plus I have yet to find anyone who has done it in the manner that I have on the L-98.
Re: How much noise have you experienced with SC cog drive? (AKS Racing)
Aaron
My cogged drive is same as TJWong. Tom's cog belt is off a Toyota Camary timing cam belt 50.7' long. My belt is off a Toyota supra/Celica timing cam belt is 53.2' long. Tom and I having the same drive setup, the only different is his are vortech blower and my are ATI D1SC blower. I am using Vortech spring load tensioner, I have to modify it in order for it to work the ATI blower and my own bracket. The noise are actually not as bad as I thought.
My pulley combo will max out the D1SC 62000 impeller speed at exactly 6200rpm. Crank is 75 teeths and blower is 30 teeths. My car is sitting in the garage (Winter) so I can't say how much boost will I see but I am sure it will in the 18+psi . My tensioner and idler pulleys are flat design (not cog) same as Tom.
Re: How much noise have you experienced with SC cog drive? (Bruce)
Bruce thanks for the info.
What is the width of the belts that you guys are running? The Polychain is 1.18".
What is the reverse bend maximum (maximum the belt is able to be bent with the teeth on the outside of the radius)? One of the critical factors in the design of a cogged belt system is the reverse bend. The design of the Goodyear belt calls for minimum radius on the bends, which limits where you are able to turn the belt. It looks as if your design pushes 70+ degrees in reverse.
As for boost, I would suspect that you will have no problem getting to the higher boost levels that you speak. Are you running aftermarket tuning? And have you stepped up to a 3 bar MAP? What was your boost prior to the cog conversion.
As a side note, at 6050RPM, you will be overspeeding the blower with your cog size selection as mentioned above.
Re: How much noise have you experienced with SC cog drive? (AKS Racing)
Aaron
The belt width is 1.02. If I can find one with 1.18 with the right length and pitch I would definately try it. As for the maximun bend that I don't know. But Tom had been running this same design and he has no problem with the bend that I know of.
My cogged setup have not see the street because I just have it completed a few months ago. My next problem is tuning and computer problem I might need a DFI. But I have been thinking about adding the superfueler I am going to get street tuning and some dyno # than I will decide what I will need to buy next.
Aaron, how did you come up with 6050rpm will max out my D1SC? Perhaps I calculate it wrong?? Total 75 teeths crank diameter is 7.3275 and blower pulley is 2.931. If you divide the # and X 6200rpm and X 4:1 step up gear I came up with 62000. Every crank rotation the blower pulley will spin 2 1/2 times. Let me know if this is right.
Re: How much noise have you experienced with SC cog drive? (AKS Racing)
Aaron, I am running a single guide pulley on my tensioner. I have no other guides on the system other than that. I am running a 72/30 tooth ratio at this time, and yes at a 6000 RPM shift I am on Votechs so called maximum impellar speed. But I had spoke to one of Vortechs lead engineers at the time I designed the system and he told me that there is a considerable safety marging built into their blowers. The mustang boys constantly over speed their blowers without any problems. I am on the ragged edge of the compressors effieciency curve so that is why I am upgrading to a T trim blower this winter.
I am hitting 10+ at shift RPM so with the T trim I will install a larger blower pulley to keep from over boosting. I have had my system in the car since late 1996 and I have had to replace the belt once. That was because I had a fuel pump failure which caused the engine to backfired and that stripped several teeth off the blower belt. One word of caution, it this happens, you had better get the car home ASAP.
If the belt looses a group of cogs it tends to slip everytime the belt rolls around, and with every bit of slippage it can loose more cogs, well as you can see it just compounds itself. Then it starts to slip on your nice aluminum blower pulley which starts to grind it down. And when that happens you have to replace it, and as you know these pulleys are all custom made and you know what that means? BIG BUCKS TO MAKE A NEW ONE :banghead: :cry
That is the one drawback of this system. There is NO GIVE at all. And when you lean the engine out or an ignition system problem comes up and it starts backfiring, you had better check the belt. It is of the utmost importance to keep the engine in a top tuned state. And I can't put enough emphasis on that one fact.
Incidentally the problem I had with a fuel pump failure was due to the fact that the system I had in place was part of Vortechs JUNK inline pump set up. That is why I endorse junking the FMU, any inline booster set up, and going to a large in the tank single pump system. At least if the fuel pump fails your engine won't run, thus necessitating that you correct the problem before damaging something else. A dual pump system in my mind SUX big time. If the inline pump fails for whatever reason, being a pump, fuse, relay, whatever. That inline pump is now a restriction because the primary in tank pump is able to pump through the inline pump. It will run the car OK for most conditions, that is until you decide to go into BOOST which is exactly what I did that day "playing" around with a Ricer Burner who I thought needed to be taught the lesson of "how not to get embarassed showing off to your girflriend by racing a blown Vette" :D Well I did lay waste to him but at the expense of a wasted blower belt and a blower pulley.
Re: How much noise have you experienced with SC cog drive? (tjwong)
Bruce,
The formula for impellor speed in a cogged system is:
Imp RPM = (crank tooth count / blower tooth count) * step up ratio * max rpm of motor
= (75 tooth / 30 tooth) * 4.10 * 6200 RPM
= (2.5) * 4.1 * 6200
= 63550 Impellor RPM
If you solve for the max RPM to get 62000 Impellor RPM, you will see that 6050 engine RPM exceeds the max impellor speed ever so slightly.
TJWONG
How are you only making 10 psi? I have 18̊ Chevy heads that flow over 370 cfm at 0.600" with a D2R that develops more boost than that. Either you have some huge by large heads/intake/cam combo, or the blower is not putting out very much CFM.
Another horror story? A buddy was running a ‘63 Nova with a large blower that he had just converted to cog belt drive. He was taking it to a car show and slowed to go over the RR tracks exiting the subdivision where I live. The motor tried to stall and he gave it gas, causing a backfire. The resultant backfire sheared the snout right off of the crank. The cog pulley/dampner/crank snout were found off the road in the ditch. It was a very clean break, and the crank manufacturer said this is common with cog drives that are mounted fwd of the stock pulley system. Basically, the extra forces applied beyond the end of the crank really strain the crank snout. This is why I think that the design I am using will prove especially useful, as the cog is mounted as far inboard as can be without removing the dampner.
Thanks for the good info from both of you guys. I appreciate the supportive feedback.
Re: How much noise have you experienced with SC cog drive? (AKS Racing)
I am only running a S trim for the moment and because of the intake restriction to Vortecs lousy intake design 12 to 13 is what I can get out of it at sea level. Plus the Vortech blowers only has a 3.45:1 gear ratio inside their gear box.
I forgot that the 10 psi I mentioned was measured at 6500 feet above sea level......oops :eek: I have found that the Vortech centrifugal blowers are very touchy as far as intake restrictions go. Any pressure drop across the intake and you will be boost restricted. Vortechs design was crap because it was meant for ease of installation for the average Joe on a bone stock engine. The blower is capable of more boost but the present intake restriction isn't, thats the problem. However given that I got 10+ out of it at 6500 feet that was good enough. I actually got 14 out of it with a different pulley combo but that was spinning the living hell out of it.
When you add 396 inches of stroked LT4, big CNC ported AFR heads flowing in the 290 CFM range (claimed by AFR) cam, and high flow exhaust, their stock design really sucks big time. I could F**T more boost into the engine than their blower could, well at least when I had a large meal with lots of beans, New Mexican Green Chili and beer! :cheers:
I have a new fabricated sheet metal intake for the new T trim, that will allow me to go with a larger pulley, drop the blower RPM, move the boost points to a lower an more efficient RPM curve on the blower map as well. I don't need any more than 10 psi here on the street with pump gas.
My cogged design is pretty much identical to what Bruce made, of course I loaned Bruce my drawings so thats partially why. But if you seen Bruces pictures you will note that our crank pulley the cogged drive is as close as you can get to the Opti unit as it can be without any interference. I don't expect any problems as you have mentioned with your friends crank snout getting wiped out. We use a 27mm timing belt that acts as a fuse in the system, if there is a back fire the teeth rip off the belt. Better to destroy a belt than a crank snout.
Wow, 18* heads flowing 370+ damn how much boost you putting to that thing? What kind of HP levels are you doing now. As for my car headwise I am stuck with AFR for aftermarket heads. No one does anything for LTx series of engines so Bruce and I are stuck with either stock castings or AFR. If I could have gone to some 18* NASCAR style heads beleive me I would have given it serious thought!
My next LTx series project is going to be a 434 inch LT1 and I am planning on a pair of raised runner 215 AFR heads for that combo, that and a Hogan Sheet metal intake or a converted Super Victor to EFI would make some serious NA numbers. It is all in the planning stages. I am waiting for Darton to finalize the new MID sleeve kit for the small block engine that would allow for this displacement in a standard small block. If it works I will have the first 434 LT1 engine :D
Post some pictures of your setup, I am sure we would all like to check it out!
Re: How much noise have you experienced with SC cog drive? (tjwong)
Aaron
You are right about the blower speed. I miscalculated the step up gear ratio. I multiplied by 4 step up gear instead of 4:1 what a dummy me. I some how left out the 1. Oh well.
Re: How much noise have you experienced with SC cog drive? (tjwong)
TJ,
The 18° heads are on another car that although street legal could hardly be classified as a street car. It is fuel injected, forced induction, but has no AC, and weighs in around 3000 lbs. The motor is much larger than the 408 (stock block L-98) that I run in my '87.
Most have seen pics of my cars and bikes (I think wou will recognize the '03Gix 1K) on the forum every now and again. Details of the '87 roadster (which is a true street car) that has dynoed at 740+RWHP and run a best of 10.02@142+ (terrible 60' car) are as follows:
408 ci stock GM block with a 4" stroke crank with all billet components
AFR 215 CP with some extra work (actual flow data of just over 310 cfm at 0.600")
MRII intake (totally cut apart, modiifed and put back together after adding progressively larger plenum area in the back cylinders)
ATI Procharger (first L-98 with cog that I am aware)
3 stage NOS system, though I have not used in probably 8 years)
FAST batch fire w/wbO2 (tuned by me)
Street twin clutch (we all remember the SPEC explosion following dyno time) w/Al flywheel
ZF (converted from auto in 1996)
3.45D-44 (fully cradled)
ZR-1 wheels (A-mold, 9.5 & 11s) 335/35ZR17 G-Force R1s
Yellow and black roadster with full Greenwood motorsport kit, lowered severly all the way around.
The '89 is a whole other story (more of a money taker than a looker).
Re: How much noise have you experienced with SC cog drive? (AKS Racing)
Gentlemen (if I may use that term), Have any of you considered using a single blade throttle body? With my T trim maxed out @ 6 grand I'm getting 17 lbs boost@5700rpm. I'm wondering if the "58" throttle body is restrictive at this point. Not that I need any more horsepower. Any ideas???
Re: How much noise have you experienced with SC cog drive? (RVY)
RVY,
What are your thoughts surrounding the 58MM throttle body? I do not see the TB as the restriction. I moreover see that I am looking to push more flow through the ngine, and if that increases the boost, than so be it. I think that I tend to run less boost than some others on the forum due to the size of the intake/heads/cam combo that I run.
You can take a P-600B (smaller ATI blower) and spin to max impellor on a relatively stock motor and get close to (if not in excess of) 20 lbs boost. Boost is merely the relative resistance to taking the given flow of air into the engine.
BTW, you do not think of us as gentlemen, and why not?
Re: How much noise have you experienced with SC cog drive? (AKS Racing)
Aaron
I currently disagree with you on the throttle body not being a restriction. I had hoped for an opinion from one of the engineers on the forum. I reflect back on the old high school physics class when we worked with water pressure and nozzle opening sizes. I see the throttle body as an air restriction. Make the tb opening larger and we can then pass a larger volume of air at a given pressure into the intake manifold. The question is, will it help or at high blower pressure is it necessary and if so, is it cost effective? I don't know.
Re: How much noise have you experienced with SC cog drive? (RVY)
One of the most basic chemical engineering laws is that PV=nRT or when comparing two different scenarios, the law may be defined as: (P1/V1)as a fx of T1 = (P2/V2) as a fx of T2.
Assumming that the intercooler in the example is capable of cooling the air down to a level that would negate the temperature increase effects of compressing the air, the formula is further reduced to: P1/V1 = P2/V2 (with all pressures measured in lbs/in2 absolute).
So, with the pressure being measured in absolute, the pressure on the normally aspirated side of the equation may be defined as 1 ATM (14.7 psia), and the volume flowed through the TB may be as designed (1000 cfm).
Based on the fact that others (as well as I) have seen boost levels at the 14-18 psi level, we shall use a boost pressure of 14.7 lbs (or 1 ATM boost). That 14.7 lbs boost equates to 29.4 psia. Insert in the formula, and you will see that the 58MM TB will theoretically flow 2000 cfm. Based on this, I would hardly say that too many people on this board would require more flow than the 58MM TB can deliver in a forced induction application.
This is also why the "rule of thumb" for cylinder heads is to take the flow (typically as measured at 0.600") and double to define the naturally aspirated HP that the heads can support. In a forced induction application, these same heads can be made to support considerably more HP due to the increase in pressure.
Re: How much noise have you experienced with SC cog drive? (bill mcdonald)
Cog set-up on my '87 L-98 requires the blower to be moved back (~1.25"), two idlers to turn above the PS pump, new lower crank pulley (which includes cog drive between the serpentine pulley and the balancer, and a new cog pulley on the blower. Blower cog belt is ~1.2" wide.
The large motor is an aftermarket block (400 based), bored 0.030" over. I run an 1/8" larger stroke than I do in my '87. It runs 9.2:1 s.c.r. (large dish in pistons) with 45 cc Chevy 18° heads (2.15"I, 1.68" exhaust, full Jesel shaft system), single 4 barrel Chevy "tall rise" intake converted to fuel injection. 2000 cfm progressive butterfly TB, D2R (discontinued by ATI in early 2002), Spearco IC. All in a lightweight (~3000#) '89 coupe. Requires a 4" aftermarket hood to clear the elbow over the TB. Also tuned via FAST.
It is not near as pretty as my '87 roadster, but it makes lots of power. It is inspected for the street. I have never run on the dyno (seems the operator is concerned about liability). He always wanted me to run the '89 on the dyno, until I ran my "slow car" at his shop.
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How much noise have you experienced with SC cog drive?
