gear drive cams

[zigzzagz]

I've heard everything from gear drives getting 5 HP more than the same cam in chain drive to no gain at all, to an actual loss in power. Of course there are better reasons for gear drive cams than a few HP but I am curious if there is any evidence one way or the other.

Also, one other question. I have fully ported T.C. heads with 1.8" int. ports 2.1" int. valve and 1.65" exhaust in my 124" B motor @10.9:1 with Woods 9f cam and HPInc 53mm t.b. and correct manifold. The manifold has not been ported or matched to the ports. Is there much of a benefit to doing this? I do notice that the HPInc manifold is a fair bit smaller than the ported super G manifold I got with these heads could this be holding up some of the power I feel I'm missing? If I could somehow get the HPInc t.b. to fit to the super G manifold via a adapter plate or something would I benefit from this extra volume?
Thanks.
zigzzagz

[Mike]

The hp increase associated with gear drive is two fold. First, is the reduced frictional drag vs. the tensioners/chains. Second is more accurate cam timing. The drag may be minimal, from a dyno standpoint, but when reduced throughout the motor can be significant. The timing is mostly a function of assembly. The pinion drive gear can have as much as 4 degrees of variance depending on if the crankshaft is rotated into or backed up on the gear when the retaining bolt is tightened. If the crank is rotated into the gear timing will typically be within 2deg or less. This is true of gear drives also but to a lesser extent because the S&S pinion gear is a tighter fit on the crankshaft. The key is to make sure the crank is rotated into the pinion gear in both cases when the retaining bolt is tightened. So a bike with worn tensioners/chains and a backed up crank could exhibit as much as a 6hp gain when gear drives are correctly installed. A hp loss I would suspect as an installation problem. The only real down sides to gear drive is the potential for increased mechanical engine noise and the added cost. For these reasons we do not neccessarily recommend them unless the application requires (I.E; .650+ lift cams and the valves springs that come with them, would benifit from gear drive).

We have seen gains with the larger manifold and our Throttle body uses the "D" manifold in all applications. This also allow us to match any port design including oval, 1.800, hybrid, raised or other for which S&S makes a manifold. We believe it is a function of reduced drag, increased volume and possibly reduced velocity which may allow the air to make the short side turn easier. Port matching is allways a good thing but can be devestating if the port is smaller than the manifold (rarely the case, but we'll see more of this when people start using the SE 50mm T-body on stock heads, it has a 1.730 port I.D.). Anything that allows the air to move clean and free helps and the increase in volume also helps absorb reversion and crossflow (the plenum effect). We have supplied a few "D" manifolds, modified for 05 and earlier EFI, to T-Man performance and I believe he has adapted the HP Inc. body to them. He has ordered 3 more and I hope to have them done soon. He has a web site and you may want to contact him. The small volume problems appear to be showing in the SE 50mm body (on both motors and the flow bench) and may substantiate the above thinking.
Regards, Mike

[zigzzagz]

Thanks for your help Mike. Also for the help and ideas you gave me when we spoke a few weeks back regarding possible light sumping in this T Man head wood cammed 124" fuelie. The bike is in at Jarz right now after it was backed into on a downtown vancouver street. Fortunately not too much damage. The bike didn't go over but instead was pushed on it's kickstand about 3 feet before the perpetrator of the foul deed stopped. There is an odd note of humour to the story though as the guy tried to take off and was swarmed by people on the street and held while I was retrieve by a panhandler who saw where my o.l. and I had gone for dinner. He made a twenty for his trouble by the way.
We will be looking into possible sumping as well as the bike is in the shop. Unfortunately I can't quite remember what you said the fix was for sumping in a B motor. I remember the drilled hole and added line for the A cases but that unfortunately won't help. Care to remind?
Thanks again your a great help and this board is an amazing resource. I've turned alot of people from Harley Tech Talk's web board on to this site, and it's very well liked and I see it quoted often now.
zigzag

[Mike]

Sorry for your mishap, but great story! Wetsumping in "B" motors usually is a pump problem. I would very suspiciuos of the o-ring in the engine case that the oil pump body plugs into. We've seen several that were not replaced when cams were installed and subsequently wet sumped. What happens is a cut or hard o-ring will not seal and the oil pump then cavitates with air from the cam chest and thus does not pull oil from the sump. I cannot remmber if you have a Fueling pump but these had a similar issue in that the interconnect from the pump to that same o-ring would drift away from the pump and allow the small o-ring on the pump side to unseat causing the same problem. T-man has been J-B welding the interconnect to the pump, we use a backup o-ring to exert pressure between the two. Fueling has supposedly addressed this problem with their newer pumps. The only other possible problem would be some sort of blockage or restriction to return oil, but this is very rare. Sometimes a piece of gasket or silicone would find it's way into or in front of oil passages (we used to call them "flappers" because they would flap up against a passage, blocking the flow and then drop back, over and over again. Drive you nuts trying to figure it out). Hope this helps, Mike

[zigzzagz]

Yes, it is a fueling pump that I have. I'm hoping these missing 10-15 Hp are as easy to find and cure as a slipped o-ring. Well, we'll know soon enough if there is any sumping or not. If I remember correctly the number we're looking for is 8 oz. of oil or less, and the bike should be run to operating temerature, stopped and drained. Is immediate draining necessary, or does the oil simply stay in the cases on a full time basis?
Would be nice to have this bike tip top before the season starts. A guy I know who is building a 114"? I think? Is having his cases sent down to you for your case vent mod. This is something that can be done with the fueling pump I understand, unlike the S&S reed valve. Are the cases as is without the venting mod creating enough back ressure to lose any noticable amount of power? Or is this mod mostly so you don't blow gaskets? I'm sure there are many little things stealing a horse or two here and there which all add up of course. What could I exect to see if I had this done and does the motor have to be out? The cases split?
Sorry for getting off the original topic here, perhaps I should have started a new thread for the other ideas but I just have this way of rambling off on a tangent you see.

[Mike]

Yes, we do have a customer sending a set of cases for those mods. The reed valve we install serves a different function from the S&S valve so we do not want people to confuse the two or expectations. The mods are for improved oil scavenging which allows for other things that might introduce more oil for the pump to deal with. They also improve the ability of the motor to exit air from under the pistons as the size of the motor increases. I cannot give difinitive dyno numbers because we do these mods as part of an engine builds so we do not have A to B testing available. We feel it helps based upon past expriance and race motors. It may just be a feel good thing but the dyno seems to support the theory. We just do not want to leave anything on the table. The cases do have to be apart for modification and we need both halves. We do suggest the Fueling pump with these mods and feel it allows that pumps advantages to be realized.
The way we came up with the 8oz. number was using a 124ci motor. We would bring the oil temp up to 180deg. (it was a warm day and we used a digital temp. dip stick), make a roll-on run, wait 30 seconds after the brake stopped the rear wheel, pull the crankcase "drain" plug and observe the draining oil. As soon as the draining oil became drips as opposed to a solid stream we would pull the catch pan and measure that oil. We tried to acount for oil cling in the catch pan as best we could and found we could accurately measure down to 1/4 oz. We then went back to the dyno charts for each of these runs to see if we could correlate hp numbers with oil measurements. We did all the testing at one time so environment changes did not factor in. We found that a 1/4 oz difference in oil volume had a measureable change in hp, above 7 3/4 oz. We have seen up to 30hp losses due to wet sumping. We did a less sophisticated test many years ago as part of Baisley's EV oil pump speed-up gears and found, routinely 10hp losses when they got much over 6 oz.
Regards, Mike

[zigzzagz]

well, it's happily worked out that my motor is not sumping. There were 2 oz of oil in the cases. Which leaves it to either not enough cr. for the TW-9f cams, or improper tuning. I'm at 135/136 STD 5th and I figure I should have another 10 HP/ and 5 - 10 TQ. The bike runs quite well, could that much power be lost in the tuning? I talked to Bob Wood, and as I suspected his solution would be, it's minimum 11.3:1, preferably 11.5:1 and 215 - 225 lbs ccp. That would likely require a new starter, and wouldn't that take quite a bit of life and reliability from the motor?
The shop that did the tune, Jarz, is a good shop run by a sharp guy in Lee but they had just been back from the tuners course about a week before when they did the bike. Before that it was hit or miss tuning and it took them a long time of trial and error to get an unusual bike like a 124 w? SERT tuned. I did ask, like you mentioned, and they do tune each head seperately. Not tune the front and cut and past to the other cylinder. They've got 8 months under their belt now so I'm not sure if I should try again, or get the new closed loop TCFI. They are coming out with a new version this month with dual a/f sensors for front and rear. Supposed to be the cats ass. You can use the ign. maps for the DTT ignitions with the TCFI too.

2.1" ported SE heads
Woods 9Fg cam @ 10.85:1 195lbs ccp
HPI 53mm T.B.
Boarzilla
SERT
3.48 gearing
135HP / 136 lbs STD 5th.

[Mike]

10HP could easily be in the tune with a 124. We've seen that with igntion timing alone. It's a function of how far out of tune the bike is. We like to see ccp 205-215 lbs. At least here at sea level much over 215 starts to get into detonation. To get rid of det. we start to take tune out of the bike, undoing what we just spent all our money on building. Higher altitudes can stand more ccp. 11.0 has proved to be a good mechanical comp. ratio for the tw9 cams and stilll run on 91 octane.
Jarz is a good shop and I would trust them!
At the risk of some criticism, I'm not a big fan of closed loop systems. The SERT mapping process should null the need for O2 closed loop. It has been pointed out that the O2 would provide another level of fine tuning once the major mapping was done and this is valid. Or, they may allow for less accuracy in the intial mapping (less time/expertise creating the initial map). I'm just not sure it's worth the added cost and complexity. The O2's are really there to take up the variance found in production (mostly the variance in flow rates of the injectors). But they are all the rage, so we'll be dealing with them as they find their way onto more bikes and maybe it will be a better world.
Thanks, Mike

[zigzzagz]

Of course, what you just mentioned is a concern, working myself out of being able to use readily available pump gas. Here in Vancouver 94 octane is get-able everywhere but not so once you get out of the city. Sometimes there is nothing better than 89 and I'd rather not be like a landlocked fish stuck in a pond. I want to be able to do some travelling and not have to worry. It may be that I'll work on the tuning and take what that gives me and run with it. Hopefully I will at least get something out of further tuning, and the shop has almost a whole year more of experience so maybe that's the ticket.
Thanks for all your help and advice Mike. It's much apreciated.

[David Jackson]

Hi Mike and Zigz;

Doesn't S&S make a gadget which senses detonation and adjusts timing to compensate?


David Jackson

[Mike]

Yes, for carbureted bikes. It's their IST ignition. We've used it on a couple of bikes and seems to work very well. It uses a knock sensor bolted to the top motor mount. In simple terms, it advances timing until knock is detected and then retards back until the knock stops. When first installed you will have some detonation because the system has to expericance that to establish limits, but it becomes gradually less, until gone, as you ride. A more complete description is available on the S&S web site. Delphi did an enteresting paper on an entire engine management system based on this concept.
Regards, Mike

[David Jackson]

I have the variable HD unit on my bike. For some reason I thought I was told that it does the same thing; but that can't be really. I wonder if I should think about changing next winter. Is it a torque enhancer?

Regards;

David J.

[Mike]

Injected models have ION sensing (fourth wire on coil) which retards ign. when detonation is detected but it does not self learn to avoid this. This is why spark plugs and cables are critical on a EFI bike. Not applicable to carb. bikes. The IST should give best torque because this is achieved with the most advance without detonation. However, torque goes though the basement when det. occures, so it's a fine line.
Regards, Mike

[David Jackson]

Hi Mike; Hi Ziggz;

Ziggz; thanks for pointing me to this site!

To Mike and Ziggz;

Would you recommend replacing the ignition set up I have now (the SE Pro Adjustable Map Ig (pn 32704-01) with the S&S one we have been talking about?

David Jackson

[Mike]

The question is, how much of a realistic gain will you get vs. cost when comparing to an improved system over stock (I.E., the S.E. ignition already installed). Retail with coil and install kit is $683.00.
The improvement is a function of how far from optimized the SE system is. Our experiance is that they are not too far off, when the correct type is used (SE has several to choose from). The other side is that you KNOW the S&S system will be optimized due to it's design (once through it's learning cycle) and does not require dyno time to do so.
Regards, Mike

[diesel_lv]

Will this S&S ignition work on a 120 Jims in an 05 bagger.

[Mike]

Should work fine. S&S has an istallation kit for 04-05 TC models, PN 55-1220.
Thanks, Mike

[zigzzagz]

Mike, you mention on an earlier post in this thread that you like to use ccp in the 205 - 215lbs range. With your twin cam motors built up to the 124" level are you able to get away with 215lbs using the stock starter? Of course I have cr. releases, and I have a rivera reduction ring gear that makes it a bit easier to turn the motor over albeit a bit slower. I'm wondering if I were to bump my cr up to where my ccp goes from the 195lbs it's at to 210 - 215 lbs, if I'd likely need another starter. This is an injected tuning with SERT. Also what could I reasonably expect to see in power gains from the 135/135 HP/Tq I've got right now. I'm shooting for 10 more HP/TQ aside and tuning is very dead on right now. Here's a link to my current dyno for your perusal though you may have to cut and paste to see it. http://www.woodcarbs.com/images/tc124efitw9bg.jpg
Cycle-rama ported 2.1" intake heads w/ 1.78" intake ports
Woods 9f cam
HPInc 53mm t.b. yellow injectors
Boarzilla 2-1.
SERT

One other thing I'm curious about, is there anyway to tell through looking at the info from race tuner in data mode? Perhaps MAP readings or other? I'm not sure if my 53mm t.b. is played out at this level. Or perhaps the manifold too small.

[Mike]

With big motors and ccp above 195 high torque starters are required. The H-D 1.4 does OK with up to 210 ccp but still struggles. The 1.8-2.0 starters really get the job done but have clearance issues on touring frames (bumps the frame just above the rear fork isolators, and requires an oil filler extension). With the ccp increase, an expected 10hp/tq gain would not be unreasonable.
We have data monitor live during all of our part throttle and full throttle runs, when collecting data for tuning changes. We watch, and sometimes log, throttle position %, map values, knock retard, warm-up enrichment and temps. We'll use injector pw, iac counts, idle settings and others to help set or correct running, starting, decel poping and other issues as part of the tuning process. Knock retard is especially helpful in calibrating the ignition tables.
Thanks, Mike

[zigzzagz]

What values would I look at when trying to decide if my throttle body is too small and what results would I see if it was the case? Or can it be determined this way?

[Mike]

In theory the MAP values could be a clue but we would not have any base to compare to. The real limit to minimum size is where the HP starts to suffer. Because of the location of our venturi, our T-body will support the same hp numbers with a smaller size than those with the venturi at the throttle plate (we call it the "Mikuni" affect, where a 42mm Mikuni carb will give sim. hp numbers as a 50mm CV carb due to smooth air flow). This is why our venturi is removable, so it can be used as a tuning aid. There is another arguement that says size really does not matter with an EFI T-body so long as it flows enough air and is not a restriction. There is some truth to this but we do have to watch throttle plate size. As the throttle plate gets larger, small throttle changes (delta) have an increasingly larger effect making slow speed drivability, idle and part throttle/off idle transitions difficult to tune. So, like injectors, the smallest size that supports our hp will be the best choice. Our testing has shown that our T-body with a 48mm venturi will support 150hp and that going larger really has no affect (positive or negative) but to achieve the same hp with a HP Inc. t-body requires at least a 52mm body. The throttle plate we use does not change and is the largest (58mm) we feel can be controlled without the above mentioned drivability problems (Zippers limits their's to 56 for the same reasons). Other things to look for on the dyno charts is simply whether the motor is making the expected hp for the combo. Another would be the shape of the dyno curve. If the torque curve goes down after peak as a flat line and the hp curve goes realitively flat that is a classic sign of air flow restriction and is either the intake side or exhuast side not allowing the motor to process air. This could be the exh. system, throttlebody size, head port limitations or inadequate cam duration.
Thanks, Mike