FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: TJ on August 16, 2022, 02:36:53 PM
-
Anyone tell me the physical differences between the Performer 390 and the Performer RPM ? They look like they have the same basic shape but the 390 has smaller tunnels and ports?
Everywhere I read and everyone I talk with says the RPM gives better performance at higher rpm and gives up nothing at lower rpm. But I'm guessing few have really analyzed the differences in performance in the 2000 to 3000 rpm ranges. And very few would have a reason to analyze the differences in the 2000 to 3000 range unless you're working the motor hard in that rpm range (like when towing). Would the smaller tunnels of the 390 give better turbulence and thus better mpg and better power in the 2000 to 3000 rpm range?
In my F250, I have a relatively tame 482 in front of a NP435 tranny and gear vendor. Rear end is 410. Adding the gear vendor got me no noticeable improvement in mpg. My guess is my particular build is more efficient around 2900 rpm (where I used to cruise on the freeway) than it is at 2200 rpm (where I freeway cruise with the gear vendor). Perhaps the lower rpm results in less turbulence and a "lazier" air:fuel mix with my current RPM intake. In theory, the smaller tubes in the 390 intake would make for a better air:fuel mix at low rpm? BTW, my engine hits peak torque at 3700 rpm.
-
you have enough cubes to justify the RPM . Difference looks like the difference between a 2x4 medium riser to a low riser 2x4
-
In theory, the smaller tubes in the 390 intake would make for a better air:fuel mix at low rpm?
That may be but, on a engine your size, it will choke it of, big time, above 4K.
I'd stick with the RPM, raise the CR, if possible and get a O2 sensor hooked up, to try and get a better, overall A/F, playing with carb adjustments. May be a water injection set up, too. Hook up a vacuum gauge, too, to see how you load the engine, with your driving.
-
The Performer 390 out of the box only flows about 230 cfm average, and the RPM out of the box flows 315-320 cfm average. I have flowed several of them, ported both, and the best you can get out of the Performer 390 is ~280-290 cfm. The RPM can be ported to 390 cfm average. For anything over 352 or 390 stock, you should definitely go with the RPM. Joe-JDC
-
Maybe I’m not reading it right but he just wants to know which is better between 2 and 3000. I don’t think he cares about above 4 or 5 thousand rpm.
-
First, I think he is confusing "turbulence" with velocity. You try to avoid turbulence, in the intake track but, velocity can help a lot, with both power and mileage.
Your right, he was asking about 2 - 3k rpm. With as large as his engine is, I think he has plenty of velocity even at 2-3k with the RPM. The engine seems to have the most efficiency at the peak torque, of 3700.
We need to know the carb type and size, as well as the Adv & .050 duration of the cam and the LSA & ICL. The bad mileage, could be as simple as to much overlap.
I forgot to add in my first post, that along with the CR increase (if possible) a decrease in quench clearance (if possible), would also help mileage.
-
The RPM is the best choice of the two manifolds, for sure.
This engine made right at 540 hp @ 5200, had 570 lb-ft of torque available at 2500 rpm, and peaked at 620 lb-ft at 3700. Any less intake would be a considerable bottleneck. Having to add throttle to compensate for a lack of power would also hurt the fuel economy. Keep in mind that this engine will idle the OP's 10-12k travel trailer around the yard while he gets out and walks beside it.
I built this engine 7 years and ~30k miles ago. It's one of the engines that was first featured on BBM's webpage. Instead of jumping right into compression ratios (9.7), quench distances (.040) and everything else, I feel like the obvious question that everyone should have asked first was......what's the current fuel economy? Hard to deem something "bad" when we don't know what it is yet. Pushing a large displacement, high horsepower, brick through the air isn't going to command big numbers. To be honest, I'd be very surprised and ecstatic if it were close to hitting double digits, especially without VCT, EFI, etc.
The carburetor tune can always be in question and a timing sweep could also be beneficial. If I remember right, total timing to make the best peak horsepower was somewhere around 30-32°, but fuel efficiency can sometimes take advantage of a different setting.
-
Appreciate all the input. I'll try to gather all the comments so far.
I'm a bit of an oddball not caring what happens above 4000...might have passed that once...rarely pass 3500. MPG isn't too bad... 11.5 - 12 if I keep it on the freeway and stay out of town. What made me wonder is the mpg did not change going with the gear vendor.
O2 sensor (when it worked) seemed good at around 13. Plugs looked okay (too me).
If air velocity is what I want then I'd think smaller tunnels would help. The engine draws a given volume. Smaller tunnels should force that to travel faster.
Might look at carb adjustments. I set up my timing curve with my "chassis dyno"...stop watch and freeway on ramp near my house. Put it in 4th and floor it from 40mph to 60mph. Adjusted timing rate of advance to get shortest stopwatch time without pinging.
I know some times companies make extra options hoping everyone will buy something but I'm guessing Edelbrock made the 390 intake for a reason. My RPM intake is installed so I can't see the ports so I was guessing they're bigger than with the 390. I have a used but uncut 390 that I ran on a 390FE I used to have. Checking differences on my "chassis dyno" would cost me some gaskets and some time. If I swap it I won't do it until winter and then test next summer.
Like I said, appreciate the input. Hope this is an interesting change of engine strategy than talking about boring hot rods :)
-
I have a 445 in my F250, with mildly ported D2 heads and a very mild roller cam. I have an iron CJ intake on it and seems to work like a champ. Plus it looks like a proper truck engine should :D
-
You don't want to make that swap.
That Performer intake is not even sufficient for a 390, much less something with 100 more cubic inches. Just because it's smaller doesn't make it more efficient. Velocity without sufficient volume is going backwards. Instead of 540 hp/620 lb-ft, you would have a huge bottleneck/hp loss, which would require you to input more throttle to achieve the same results in cruising, towing, etc. Not a good scenario.
12 MPG would make me giggle. My uncle's 1993 Chevy 454 dually with 230 hp got 8.
Try some total timing adjustments over a period of time, hook up a distributor with vacuum advance.
-
Throwing my 2 cents in, you will lose power everywhere and gain nowhere. The RPM is a well designed manifold, the Performer 390 was built at least a decade earlier and a cork. Your theory is potentially correct, but the Performer 390 won't do what you want
If you really think you want to shift the RPM range even lower (in what was a really cool build already if I remember it correctly), it likely means a cam change to change the peaks and likely a compression change to support the cam, but even then, you likely won't get paid back in mileage for the cost
I think you have what you have without big investment and it's pretty darn good, if you want to turn it into a tractor or make it run at diesel levels, you will likely lose a significant amount of power. IMHO this is a 482, they use more gas...14:1 mixture..., the displacement is 90 cid higher, that means the 14 and the 1 has to be increased filling a bigger cylinder. It'll cost you money and power without any real payback
-
Okee doke. I'm almost convinced...still curious what would happen in 2200-2900 rpm range...
BTW, the 11.5 - 12mpg is empty. Roughly 7.5mpg pulling the fifth wheel but haven't pulled enough to be confident in that number.
I feel my timing is optimal at this point. Might talk with my guy on carb adjustments for lower rpms.
To be clear, the engine is doing just what I want. I'm wondering why dropping 24% rpms (2900 down to 2200) didn't give me at least a smidge better mpg.
-
Okee doke. I'm almost convinced...still curious what would happen in 2200-2900 rpm range...
BTW, the 11.5 - 12mpg is empty. Roughly 7.5mpg pulling the fifth wheel but haven't pulled enough to be confident in that number.
I feel my timing is optimal at this point. Might talk with my guy on carb adjustments for lower rpms.
To be clear, the engine is doing just what I want. I'm wondering why dropping 24% rpms (2900 down to 2200) didn't give me at least a smidge better mpg.
Brent mentioned vacuum advance, are you running one? May not be drastic improvement, but that's what it's there for.
-
I'm wondering why dropping 24% rpms (2900 down to 2200) didn't give me at least a smidge better mpg.
Because the engine is in the same efficiency band across that entire rpm range.
You honestly need to stick it on a real chassis dyno in order to get the most out of the carburetor and timing adjustments. I can't remember what you're running now for a distributor, but it seems to me that we dyno'd the engine with a Mallory or something. Adding a vac advance distributor would most likely help.
Changing your driving habits can do a lot as well.
Above that, something like a MPFI system would help, where the computer is mapping and adjusting the A/F ratio and the timing curve on the fly.
-
Sheesh, doesn't anyone on this thread have my book? The data from 2500-3000 is all in there, Performer vs Performer RPM. On my 410 HP 428CJ, the Performer makes torque of 389 to 438 lb-ft from 2500 to 3000 RPM, and the Performer RPM makes torque of 340 to 406 lb-ft. On this engine the Performer is better in this range, and is actually better than the RPM up to 3500 before the RPM takes over and makes a lot more power. Both intakes peak at nearly the same torque, 485 lb-ft around 3500 RPM.
On my 500 HP 390 stroker engine, I only tested from 3000 RPM up, but basically the two manifolds behaved the same as the other engine from 3000-3500. But on that engine the RPM made more peak torque, and caught up with the Performer a little sooner.
I have heard a lot of anecdotal evidence that the Performer RPM is better than the Performer 390 at all engine speeds, but it is all based on the "seat of the pants" dyno, not actual data. I'll stand by the back-to-back test data in my book, and say that the Performer 390 is better than the Performer RPM up to around 3500 RPM.
-
Sheesh, doesn't anyone on this thread have my book?
Well sure, but data is relative and not every engine is a 410 hp 428CJ or a 500 hp 390 stroker with the exact combination of parts that you had. When looking at data such as this, I consider the entire engine build as a whole and realize that the build just may not be efficient enough in a specific rpm range to take advantage of one intake or another.
We are zooming in on how well an engine can get a specific volume of air/fuel charge moving, and if a larger intake doesn't show as much hp/torque at a lower rpm as with a smaller intake (but peak numbers are the same), then it just simply means that the engine can't pull hard enough at that rpm to get that specific volume of air/fuel charge moving. Camshafts play a huge role in that and I would venture to say that if different cams (read smaller) would have been used, the results would have been much different at those lower rpm ranges. It actually makes perfect sense that an engine with a healthier cam would make more power in a low rpm range with a smaller intake.
Aside from all of that, the OP's engine is much larger than a 428 or a stroked 390 and the camshaft was only 224° @ .050" duration. That engine should pull hard on whatever intake is bolted to it and it will make the power as long as the intake manifold's capability is higher than the cylinder head's capability. Per Joe's point, a 230 cfm intake on a 290 cfm cylinder head will be a bottleneck.
-
Sheesh, doesn't anyone on this thread have my book? The data from 2500-3000 is all in there, Performer vs Performer RPM. On my 410 HP 428CJ, the Performer makes torque of 389 to 438 lb-ft from 2500 to 3000 RPM, and the Performer RPM makes torque of 340 to 406 lb-ft. On this engine the Performer is better in this range, and is actually better than the RPM up to 3500 before the RPM takes over and makes a lot more power. Both intakes peak at nearly the same torque, 485 lb-ft around 3500 RPM.
On my 500 HP 390 stroker engine, I only tested from 3000 RPM up, but basically the two manifolds behaved the same as the other engine from 3000-3500. But on that engine the RPM made more peak torque, and caught up with the Performer a little sooner.
I have heard a lot of anecdotal evidence that the Performer RPM is better than the Performer 390 at all engine speeds, but it is all based on the "seat of the pants" dyno, not actual data. I'll stand by the back-to-back test data in my book, and say that the Performer 390 is better than the Performer RPM up to around 3500 RPM.
I love your book and reference it regularly, but IMHO, and honestly with all the peer respect anyone in the world could muster...it's testing is far from this target. WOT dyno runs on smaller engines with curve analysis, I think, just doesn't match the part throttle and mileage discussion. I really don't know, nor does anyone really know how throttle jockey movements will respond between the two. For me, on a small motor, 390 with 270H and a 600, the Performer 390 was pitiful and a PI and a unmachined SD were both nice to drive.
That being said, in the end, he is looking for seat of the pants and mileage, so I don't see any reason other than buying and fitting a manifold not to do it, but I cannot imagine it's the right thing
We do have a big inch engine that did exactly this, Turbohunter's truck. Marc ran a stroker with a Performer and the world didn't end, but on the other end of the spectrum I run a Victor on my 462 and it makes tons of torque, and got 14 mpg with a 3310 before the fuel injection.
I'll admit it's not scientific, but I do think it's going to lose enough power that it will be less effective through each shift. I say go for it if he wants to try it
-
To be clear, the engine is doing just what I want. I'm wondering why dropping 24% rpms (2900 down to 2200) didn't give me at least a smidge better mpg.
On the highway it takes X amount of horsepower to push your truck through the air at 70 mph. Semi's with 53' Vans take about 270 Hp, Corvettes take about 35 hp, your truck falls somewhere in the middle. Your engine has to generate that same horsepower whether it is running 2200 rpms, or 2900 rpms just to push the truck along. If all other things are equal, and your burning fuel stoichemetrically, then you need to burn the same amount of fuel to generate the same horsepower regardless of engine RPM.
The difference that occurs, is the engine has less rotating resistance at 2200 RPM's, which should help to increase your mileage, because at 2200 rpms you would expect that it only takes X-5 or so horsepower to move the truck down the road. However, the overdrive robs power, and as you suspect, there is probably some decrease in efficiency in the intake track at the lower rpm, but I would venture to guess the OD is the big killer. The big truck guys figured it out a while ago that a tall rear axle and one-to-one final on the transmission is more efficient than a deep rear axle paired with an overdrive.
-
To be clear, the engine is doing just what I want. I'm wondering why dropping 24% rpms (2900 down to 2200) didn't give me at least a smidge better mpg.
However, the overdrive robs power, and as you suspect....
An excellent point that I didn't consider at first. Anything that's slapped in between the transmission and rearend will suck some power.
-
To be clear, the engine is doing just what I want. I'm wondering why dropping 24% rpms (2900 down to 2200) didn't give me at least a smidge better mpg.
Besides the frictional loss, in the gears, it may also have put the engine, in to a range, where it's less efficient and is "lugging". A vacuum gauge would help in determining that and a switch to a lower final drive or a higher w/o the Gear Vender.
If your not concern about 3k>, a smaller carb (550-600 cfm) could help. Your engine is only pulling 418 cfm @ 3k. Try to tune it for 14.5-15/1 A/F at lighter throttle cruise and 12.5-13/1 at low vacuum. That's what power valves are for, right?
You could also, advance the cam 2/4° and pick up low end torque. Be careful of to much compression here.
Again, water injection and cool intake air.
When tuning for MPG, a vacuum gauge is very important. Get your O2 sensor going again, too.
-
Cam needs to stay where it is on this one and advancing the cam doesn't always "pick up low end torque". Depending on the camshaft and the entire engine combination, it *may* increase throttle response, or it may not. It *may* push the hp curve down and then again it may not. There are no absolutes, except for that it will raise cylinder pressure and you don't want that here.
-
Only one way, to find out, for sure.
For his application, I believe he needs ~218 @.050 duration, with the Adv duration, adjusted for DCR, as well as minimum overlap.
You need to get that 3700 rpm, max torque down to 3000/3200 rpm.
One last thing, is to use a carb with annular boosters, if you an find one.
-
Only one way, to find out, for sure.
For his application, I believe he needs ~218 @.050 duration, with the Adv duration, adjusted for DCR, as well as minimum overlap.
You need to get that 3700 rpm, max torque down to 3000/3200 rpm.
One last thing, is to use a carb with annular boosters, if you an find one.
If you would share the data from your past FE engine builds that would lend themselves to this conclusion, I'd be interested in seeing it. Mind posting it up?
-
Brent, it doesn't take much, to see that this engine, was not built for what the OP's requirements are and many different things, need to be changed, to meet his current goals.
Simple as that.
-
Brent, it doesn't take much, to see that this engine, was not built for what the OP's requirements are and many different things, need to be changed, to meet his current goals.
Simple as that.
Oh, when he wrote, "To be clear, the engine is doing just what I want", I kinda took that as it was actually doing what he wanted. Who would have guessed that the whole thing needed to be replaced? :facepalm:
-
Of course nobody has done a true AB test on this, but I have some data that may help with conclusions. When I first got my Merc it had a good running 390 in it with Ebrock 600, Perfomer intake, Performer cam. It got 15 with stock 3.00 gear and a COM
I swapped in another 390 with 224* cam, Performer RPM, 750 Holley, and a T10. With 3.00s it got 15mpg.
With 3.50s it got 14, 4.10s it got around 9mpg, and putting in a TKO it gets 17mpg.
So, in my combo of a fairly large ugly Merc, with similar 224* cam, it got decidedly better mileage dropping the rpm. With extra 100ci with same size cam, can’t see how dropping rpm would cause it to lug to a point it’s losing mpg.
I’ve had my car on a chassis dyno, it peaked at 3500 and 5400
-
Haven’t read every reply, but have you tuned the PV circuit with the OD? Assuming it’s a Holley. Lower rpm and more gear mean it’s likely pulling less vacuum at cruise, could be opening the PV sooner on grades.
I had an M715 with 4.56s but 38” tires and a tall deck 427 bbc bus motor. It had an Edelbrock 700 on it, I put an AF gauge on it and didn’t change main jetting but changing out the metering rods and springs to lean out the transition netted 2mpg as it was very fat when I’d roll up grades
-
Thanks to all for the ideas.
Apologies to Jay for not looking at the Comparo: I have no good excuse. I tend to believe there is a time and place for the Ebrock 390.
Dizzy: Yes, I have a vacuum advance and like it. I think it's fairly well dialed in but going on personal preferences and a stopwatch there.
HP demand: I get what FrozenMerc is saying about needing X amount of power at a given speed though I figure this much displacement is wasting more gas just by running than it actually needs when the truck is empty. Lower rpms should permit it to waste less gas.
Gear vendor: Maybe it's costing me power and mpg but sure seams like a lot. I like it if for nothing else than splitting 3rd and 4th and lower rpms on the freeway. Perhaps it contributes to the overall stacking of tolerances.
Cam change: Thought crossed my mind but in no hurry to do that because it costs decent amount of money and time. Plus I think I have a few other things to try first.
Engine not meeting my needs: Thought that comment might have been a joke but in case it wasn't...We have a 2002 Duramax we've used it to pull our fifth wheel through 40 of the lower 48. And we really like it. If that somehow gets fubarred, I'd seriously consider finding an '80s or 90's crewcab to stick this 482 in and pull our camper around the country because I like it that much. Really, I'm just puzzled why lower rpms didn't help mpg. Thought intake was something to consider. Now I'm thinking carb adjustment might benefit.
Carb PV: That's something I need to read up on...as well as get a new O2 sensor. That's sounding like my first thing to check.
-
If you are serious about the Performer 390, I have a new one that is ported and flow balanced that I will swap you even up for your used RPM if you pay shipping both ways. You get a new Performer 390 intake, $500.00 worth of porting, and it will flow 290 cfm average. Ship me the RPM and I will send you the ported new Performer 390 in the same box with you paying shipping back to you. PM me if interested. Joe-JDC
-
First Joes offer is very generous and might bridge the gap nicely between a stock for stock intake.
I have a thought on your mileage not improving with the OF.
From my own,insane, cruise carb tuning on a BG 800 on my 433ci FE that got 18mpg with 3.70 gear and TKO .64 At 75mph I can say dropping cruise RPM from 2900 to 2000-2200 puts the carb in a high load condition. Add your truck being much heavier than my Mustang and I bet your running on the main jet AND opening the power valve (Holley?).
If your running 13:1 at cruise,2200rpm that will be costing you 2-3mpg for sure. The problem is that load and engine set up will want a bit more RPM.
With an O2 indicator,Vacuum gauge and tach if you pay attention to minor changes you can actually see the carb circuits stack one on another. I found it interesting how much time the engine runs on the transition circuit NOT the main jet.
What could be happening is at low rpm your actually running on the main because you have the throttle blades opened more than you do at lighter load at 2900RPM where it’s actually running on the transition circuit.
Add the fact that low rpm high load is dropping the vacuum so the PV is open as well.
It might be said your lugging the engine.
At one point my Mustang had a cam in it that caused the car to chug below 2300 rpm, but was smooth at 2600.
With my 3 tools above I could see how messed up the fueling was below 2500rpm.
Paying attention to the vacuum at the same road speed in D and OD then maybe D at the same RPM that the OD drops the engine too (even though it’s a lower speed) may help you understand the load the engine is seeing.
I found it very interesting and rewarding how simple jet ,air bleed ,and IFR charges effect the fuel curves.
-
There is a real fine line at 2k rpm range. Throttle opening is VERY critical to economy. Try to ease up on the throttle until your speed just starts to decline. Close throttle on any downgrade. You're the computer now!
Cyclone3 is on the money !!!!!
Ron.
-
Do you have a vacuum gauge hooked up and if so, what are your readings in hi gear and OD at different mph/rpms ??
Loaded and unloaded ....
What carb is on your mill ??
Heads, valve size, ported ??
Complete cam specs ??
Exhaust ??
Just curious and keep a mental note of things such as this
Ricky.
-
Engine not meeting my needs: Thought that comment might have been a joke but in case it wasn't...We have a 2002 Duramax we've used it to pull our fifth wheel through 40 of the lower 48. And we really like it. If that somehow gets fubarred, I'd seriously consider finding an '80s or 90's crewcab to stick this 482 in and pull our camper around the country because I like it that much. Really, I'm just puzzled why lower rpms didn't help mpg. Thought intake was something to consider. Now I'm thinking carb adjustment might benefit.
Carb PV: That's something I need to read up on...as well as get a new O2 sensor. That's sounding like my first thing to check.
Sorry TJ but, it was this statement, that I was going by:
I'm a bit of an oddball not caring what happens above 4000...might have passed that once...rarely pass 3500.
If that's the case, your peak hp @ 5200 and peak torque @ 3700, would seem to be wasted hp, torque and gas.
-
I see this as potentially too little gearing for use. 28% reduction of 4.11 is a 2.95 gear, pretty tall, especially depending on tire height.
In my Mustang with a 27.5 inch tall tire, I went from about 12 mpg to 14 mpg, and a much more comfortable drive when going from 3.70s to 4.11. In town traffic was far better on fuel too. I went from 2.36 to 2.63 final, but my car is a lot lighter and less frontal area than a truck. I can't overdo how much nicer it was everywhere when I wasn't lugging and I also drive mine easy (until I don't LOL)
My truck does pretty well, but it is a 1:1 tranny 3.50 gear, 32 inch tall tire 4x4 with no overdrive. I will someday adapt an OD, but when I do it will likely get 4.56s or so
I am not advocating a gear change for mileage alone, but a gear change to 4.56 would put you at 3.28 final in OD (assuming I have the .72 number correct) and may make the truck happier on OD when unloaded, and certainly happier when loaded.
Just a thought.
I'd also add that OEMs have added intermediate gears (more gears) in a tranny to get mileage, they haven't hobbled performance, even the smaller motors, so you could spend a thousand or more as an experiment on cam change, maybe more with a smaller runner head swap, intake swap, new pistons, etc,, but you don't see the gasser modern trucks do it, they add 8 or 10 speed trannies so they get mechanical advantage everywhere and OD on top.
-
Trying to respond to as many ideas as possible...
Appreciate the offer on the ported intake. If (and that's a big IF) I swap intakes, I'll want to see what the out of box 390 does first. At this time, I'm planning to stay with the RPM
Yeah, I'm definitely running a vacuum line through the firewall to watch vacuum at various scenarios. Spent too much time reading on power valves and carb circuits last night...steep learning curve for me there.
There's been a few questions on the carb...it's a 780 Quick fuel. All I've done to it is switch to a manual choke primarily so I can manually set a fast idle for warming up. Rest of the build is in the dyno section.
[/quote]
If that's the case, your peak hp @ 5200 and peak torque @ 3700, would seem to be wasted hp, torque and gas.
[/quote]
Maybe so. I'm curious what moving the hp and torque peaks would do but no plans to find out.
- We really like our duramax and have no plans to tune it or get a newer truck...it pulls our fiver well. This 482 pulls our camper in overdrive with throttle left over and will out run the duramax up hills with the camper...without passing 3500 rpms.
- If the engine changes that move peaks to a lower rpm also result in less torque then I'll likely stay where I am. I'm at 580 lb ft now at 2500 rpms. If the torque peak was moved to say 3000 rpms, would I have more or less than 580 lbft at 2500?
-Then glancing at the current Ford 7.3 gasser, its torque and hp peaks are both 300 rpms higher than my 482. And at 2500 rpms my 482 has more torque as a percentage of its peak than the new 7.3 gasser has. My 482 makes 93% of its peak torque at 2500 rpms. The 7.3 makes around 90% of its peak at 2500 rpms.
-Even if I currently had a torque peak at say 2600, I'd be wondering what if the peak was at 3000 or 4000.
For gear changes, I've spent a lot of time calculating and theorizing. Going to a 4.56 rear is something I haven't considered but will have to think about. BTW, the gear vendor is 0.78 overdrive.