8lb vs 10lb? Roe Supercharger gurus welcome!

[g3t_t0rk]

I've done my research and all of the threads I found were from mid-2000's so I just wanted to confirm: which pulley is superior?

My findings were that the 8lb pulley and 10lb pulley were exactly the same whp but the 10lb has the edge on torque, about 30wtq. However, on hot days, the 10lb will generate much more heat soak and as a result, more power will be lost. The 10lb pulley should only be used for those with ported heads. Is this correct? I currently have the 8lb pulley and I wanted to pulley down to a 10lb pulley next year after I put some headers on. I'm currently sitting on 634whp/658wtq (with water/**** injection) and I'd like some more power but now I'm not so sure if the 10lb pulley is a step in the right directions. Can I get some $0.02 from others that have had experience? Much appreciated

 

[speedracervr4]

When I had the 2.4L blower with unported heads I gained 20rwhp/15wtq on a conservative tune. I know a few guys run the 10lb pulley with stock heads with no issues. Make sure your tune and water **** system is on point as the intake charge will be hotter.

 

[Red Snake]

On stock bottom end and unported heads, When i stepped up from 8 pounds to 10 I added;

Fuel pump 255
Water ****
10 pound pulley and belt

I went from 635rwhp/675rwtrq to 660rwhp/710rwtrq. Both dyno days were 100 degree plus in the dyno shop.

 

[EllowViper]

Bottom-line: Just have fun with it and don't over think things too much..LOL. In your research, you should have discovered that no two ROE installations are the same. Just like no two water/**** installations are the same. Nor are water/**** concentrations the same. Nor are spark plugs the same. Nor are air boxes, throttle bodies, or tunes the same. So asking which pulley is superior will result in very subjective and non-objective opinions. Some I know (Tim) have higher numbers on a completely stock creampuff motor with a 6.5 pulley than those with more boost on built motors. With that said however, I know what you are trying to get at and can sympathize with your delema (been there). You wanted $.02...here it is: Go with the #10 pulley. Heat soak is not an appreciable issue (max of 20 degrees hotter w/2 PSI increase) and that can be controlled with a corresponding change in W/M and tune. Plus most of the time, you're going to be experiencing the boost in short bursts anyways (where its the most fun!). Look at it this way. You're bored at 634/658 and after a few months, you'll be bored at whatever numbers 10 PSI gives. Its just the crack addiction you get with a ROE. Case and point, I've gone from a 5 psi pulley, 6.5 psi pulley w/water-****, 10 psi pulley on an upgraded 2.8H blower, 10 psi pulley with Weaver crank pulley (13 psi), back to just the 10 psi pulley, and now 17 PSI (#12 psi pulley and Weaver crank pulley). It's all about having fun, learning this and that about your motor, trying new things for the sake of trying new things, and sharing your experiences with others. I love posts like this since it really fuels the ownership experience unlike any other toy. And as such, I'm sure you'll continue to get $.02 from other ROE owners with other experiences.

 

[g3t_t0rk]

Thank you all for the .02 and insight! Looks like the 10lb pulley is back on the to-do list

 

[GTSnake]

I've had my bad experiences with the Roe. Had the 10lb pulley and later found out the Roe isn't rated to be used with the 10lb pulley. If you have a good tune and don't drive it that much you may not have any issues. Also make sure you check the SC is full with oil every time you change engine oil. They have a habit of consuming oil. Mine ran dry and seized because I didn't check it regularly.

 

[g3t_t0rk]

I've had my bad experiences with the Roe. Had the 10lb pulley and later found out the Roe isn't rated to be used with the 10lb pulley. If you have a good tune and don't drive it that much you may not have any issues. Also make sure you check the SC is full with oil every time you change engine oil. They have a habit of consuming oil. Mine ran dry and seized because I didn't check it regularly.

Any info on the Roe not being compatible with the 10lb pulley?

 

[speedracervr4]

I've read on here somewhere that with the 2.5" pulley with the 2.4L you're at or near max rpm of the blower. However, there are plenty of guys with plenty of mileage with no issues with the 10lb pulley. The 2.4L or 2.8L are not great matches for our 8.0L engines, but the hood sits too low for a bigger blower. Sean uses a 3.4L blower on the truck kit since its got the room.

 

[EllowViper]

Max you can [safely] spin the blower is 18,000 rpm according to Kenne Bell.
On a stock crank pulley (7.375 in diameter) and a 10 psi blower pulley (2.5 in diameter) your ratio is 2.95. 2.95 x 6000 rpm = 17,700 rpm. So you are within the margins and should be OK. For comparisons sake, I'm at a 3.33 ratio (8 in crank pulley and 2.4 in blower pulley) and at 6000 rpm, I'm spinning the 2.8H at 19,980 rpm. Some of the Mustang guys are spinning their Kenne Bells at over 21,000 for short bursts without issue. I would say sustained at over 18,000 one [could] have some issues. I guess time will tell, but when I had the older 2.4 and 10 PSI pulley, I spun it right up to max all the time and when I sold it, the rotors looked like new...used zero oil and I never had to add any to it ever.

 

[martyb]

I thought the max rpm was 15k for the older roe blower??

 

[g3t_t0rk]

Max you can [safely] spin the blower is 18,000 rpm according to Kenne Bell.
On a stock crank pulley (7.375 in diameter) and a 10 psi blower pulley (2.5 in diameter) your ratio is 2.95. 2.95 x 6000 rpm = 17,700 rpm. So you are within the margins and should be OK. For comparisons sake, I'm at a 3.33 ratio (8 in crank pulley and 2.4 in blower pulley) and at 6000 rpm, I'm spinning the 2.8H at 19,980 rpm. Some of the Mustang guys are spinning their Kenne Bells at over 21,000 for short bursts without issue. I would say sustained at over 18,000 one [could] have some issues. I guess time will tell, but when I had the older 2.4 and 10 PSI pulley, I spun it right up to max all the time and when I sold it, the rotors looked like new...used zero oil and I never had to add any to it ever.

Wow. Good info!

I thought the max rpm was 15k for the older roe blower??

Also an interesting question.. Looks like more research is to be done!

 

[EllowViper]

There is a difference between max RPM and sustained RPM. Sustained RPM on Eaton and some older Autorotors were listed ~13k-15k...so yes, the older ROEs would fall into this category. But again, sustained vs. max are different limits (also what I have read is that the max limits were not so much a limit on spinning, but on blower efficiency; where beyond 18,000 RPM, the blower was not in its efficiency 'sweet spot' any longer. Similar to proper sizing of a turbo). From what I have researched, the older 2.4s can still be spun to a max of 18,000 just like the newer Blowzillas. Nothing really changed internally. I certainly wouldn't spin mine at 18K sustained without some water/methanol being sprayed to cool the intake charge, case, and rotors. A big issue is thermal expansion beyond clearance tolerances. If you overheat/over expand, you will cause metal on metal contact and that is not a good thing!! Ergo the development of their liquid cooled cases. From a sustained RPM perspective, the relatively cool airflow going through the blower maintains a static level of heat/expansion...i.e it won't get any hotter/cooler all things being equal...just happilly pumping along. At max boost/max RPM...understandably the load, friction, and pressure induced heat will change that happy condition. So if one is aware of the effects of heating, case and rotor expansion, and how to control intake charge heat, none of this is really an issue.

 

[g3t_t0rk]

There is a difference between max RPM and sustained RPM. Sustained RPM on Eaton and some older Autorotors were listed ~13k-15k...so yes, the older ROEs would fall into this category. But again, sustained vs. max are different limits (also what I have read is that the max limits were not so much a limit on spinning, but on blower efficiency; where beyond 18,000 RPM, the blower was not in its efficiency 'sweet spot' any longer. Similar to proper sizing of a turbo). From what I have researched, the older 2.4s can still be spun to a max of 18,000 just like the newer Blowzillas. Nothing really changed internally. I certainly wouldn't spin mine at 18K sustained without some water/methanol being sprayed to cool the intake charge, case, and rotors. A big issue is thermal expansion beyond clearance tolerances. If you overheat/over expand, you will cause metal on metal contact and that is not a good thing!! Ergo the development of their liquid cooled cases. From a sustained RPM perspective, the relatively cool airflow going through the blower maintains a static level of heat/expansion...i.e it won't get any hotter/cooler all things being equal...just happilly pumping along. At max boost/max RPM...understandably the load, friction, and pressure induced heat will change that happy condition. So if one is aware of the effects of heating, case and rotor expansion, and how to control intake charge heat, none of this is really an issue.

Seriously good info. Btw, what weight oil does the 2.4L use? Also, would using a heavier weight oil along with water/**** injection combat heat/expansion? Also I remember you saying that the difference of 2psi translates to 20 degrees hotter. What exactly does that mean performance wise? More heat soak yes, but is there a limit to how hot the air temps get or does it get worse?

 

[g3t_t0rk]

Is this the same 2.4L in our cars? http://www.not2fast.com/turbo/maps/AUTOROTORvsLYSHOLM.pdf

 

[GTSnake]

Any info on the Roe not being compatible with the 10lb pulley?

After talking at length with PSE (http://www.pse.us/) the people who repair Roe blowers they told me that the Roe is not rated at anything above 5lbs. That doesn't mean it won't work it just means it exceeds what it was designed for. So over the long run it will fail earlier. After I had my Roe repaired I went to turbos.

 

[speedracervr4]

Sean recommends using Castrol SYNTEC 5W-50. Kenne Bell also sells an oil that's a different color so you can tell if it's leaking. Do not fill the casing to the top, only fill it to where the dip stick is marked. If you don't have a dip stick you can make one pretty easily.

The kits used two different size blowers (both 2.4) depending on when it was ordered. One of the blowers has a longer case like the KB 2.8.

Sean has mentioned to me that he never really designed the kit for more than 5lbs, but people got addicted to the power. Mustang guys spin the blowers just as much with no issues.

 

[EllowViper]

Good Discussion. Its been a few years since I've had to cover this ground again. The biggest thing you can do to kill the blower is overfilling the reservoir. You overfill and you will build excessive heat in the gears and melt the green nylon spyder connector (by design). But it’s not the overspinning that kills it, but the heat that is generated. When I discussed my specific situation with Kenne Bell (remember I was the first to fit the 2.8 blower as a replacement to the 2.4 and Sean even discussed what I learned from the process with me…aka you need the 03/04 Cobra hub connector to mate the drive extension to the blower), their tech rep (Matt) advised me that spinning it that fast was no big deal, but to make damn’ed sure I kept the oil level at the lower mark. He stated the majority of blower failures that they get were due to folks putting too much oil in the blower and blowing seals, over heating the green spyder gear, and thereby over heating the blower. The viscosity and amount of oil is of critical importance. Who’d have thought? A bit too much oil and it creates excessive friction in the gears and quickly heats up and can’t be dissipated. A little low on oil is actually better than too much oil (not my words).

 

[g3t_t0rk]

Good Discussion. Its been a few years since I've had to cover this ground again. The biggest thing you can do to kill the blower is overfilling the reservoir. You overfill and you will build excessive heat in the gears and melt the green nylon spyder connector (by design). But it’s not the overspinning that kills it, but the heat that is generated. When I discussed my specific situation with Kenne Bell (remember I was the first to fit the 2.8 blower as a replacement to the 2.4 and Sean even discussed what I learned from the process with me…aka you need the 03/04 Cobra hub connector to mate the drive extension to the blower), their tech rep (Matt) advised me that spinning it that fast was no big deal, but to make damn’ed sure I kept the oil level at the lower mark. He stated the majority of blower failures that they get were due to folks putting too much oil in the blower and blowing seals, over heating the green spyder gear, and thereby over heating the blower. The viscosity and amount of oil is of critical importance. Who’d have thought? A bit too much oil and it creates excessive friction in the gears and quickly heats up and can’t be dissipated. A little low on oil is actually better than too much oil (not my words).

I remember reading about how much to fill the oil level but Kenne Bell only shows how much to fill with how much psi you're running. 8-10lbs would be right in between the 2 lines on the dipstick, correct?

 

[EllowViper]

That would probably be a good level IMO. Sometimes its really hard to see the oil film on the dip stick so check/verify your measurements several times.

 

[brentsGTS]

For you 8 & 10psi guys, what fuel system mods are you running? I know **** is required but what else? Can one do it with 60lb injectors and a bap?

 

[speedracervr4]

I run dual 255 Walbros on the stock lines, but you could probably run a 255 and a BAP. Some have been able to run the stock pump with a BAP,every car is different.

 

[brentsGTS]

How much power are you making with that setup? Seems some are getting away with just a bap and maybe a pump.

 

[plumcrazy]

dont do a BAP, do it right

 

[EllowViper]

This is for my 2001 which is a bit different that earlier GTS pump designs. Not sure what year your's is. Here's an idea that I tried but ended up doing something different since the opportunity presented itself. Take the stock line completely off (from the quick connector on top of the tank to the front of the firewall…including the filter). Heck, I guess you could just leave it all in place if you want…but I pulled mine completely off. Get one of those fancy -AN6 connectors that are designed to clip into the factory fuel pump out line (where the original line you took off connected). I can't recall the exact fitting, but JEGS/Summit have a variety that are designed to fit over factory fittings. From that new connector, run a new -An6 line where the factory line was. You can install a high flow replaceable in-line filter in the tunnel at this time as well. Terminate the line at the "T" for the ROE system with another -AN6 fitting. What this does is eliminate the flow and volume restrictions the factory line has. In just doing this, my fuel pressure went from the factory 55 psi to 65-70 psi as measured at the fuel rail. I believe simply removing the fuel filter freed-up available flow and that the stock filter somehow was actually acting as a check valve to some extent letting available pressure get dumped back into the tank keeping pressure at 55 PSI.…my opinion. And yes I do know how the factory regulator in the tank works to maintain a pre-set pressure. But I do also believe that the factory regulator may or might be somehow calibrated to work in conjunction with the factory fuel filter. From what I have researched, no one has actually tested that idea however. But like I said, I measured fuel pressure before and after and this is what I saw (and maybe my filter was getting clogged…who cares). Back to your original question…Originally I ran a BAP with the factory everything with a 10 PSI pulley and the 42 LBS Green Top Boschs. I never saw a drop in fuel pressure. But like has been said, everyones' experiences are different.

 

[brentsGTS]

Anyone have a part number for that fitting? That connects to the stock hat? What about the attachment to the rails? What's needed there?

 

[speedracervr4]

IMHO if you're staying with a basic 10lb setup, I would add a pump and maybe a BAP and stick with the stock lines. The reason I went dual Walbros is because I was contemplating on going TT. The previous owner of my car had the stock pump with a BAP with a 10lb pulley (630rwhp). My Viper is a 99, so I'm not sure if the fuel hat/pumps are different than Ellow's. I think the Roe kit came with the line for the rails.

 

[brentsGTS]

I think a 255 with upgraded feed line would be great and a bap for a 12lb pulley.

 

[g3t_t0rk]

For those with 255lph Walbros, I recommend upgrading to Lethal Performance's Styker 340lph fuel pump! It's a direct replacement and it flows much more. I'm sitting on 630whp and I haven't maxed out the fuel pump yet on a single fuel pump! Also, it's only $150!

 

[Martin2000GTS]

my stock pump with BAP limited me at 680, Chuck is putting the 255's in now. along with a transmission...ehh

 

[Martin2000GTS]

g3t t0rk - thanks for the insight, I ended up with a single 400lph pump from Roe