Author Topic: Wood TW-6HG vs TW-8G in a 98"  (Read 1009 times)

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Offline Winston Wolf

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Wood TW-6HG vs TW-8G in a 98"
« on: August 26, 2019, 09:44:22 AM »
I have a 98" with 10.5:1 Mahle pistons, Wes Brown ported heads and intake, running a Mikuni HSR42 and a DTT ignition with a custom curve.  Dyno sheet below with TW6HG cams and the 3 exhausts I have.

Has anyone dyno'd a 6HG vs an 8G in (or chain driven), in a smaller engine like this 98"?  I'm thinking of swapping cams to try and get a little more out of the package.  This is in a 2002 Lowrider, so it's a fairly light bike.  Want to keep up with the new Milwaukee 8's if I can...  This is just a little hotrod bike for me, but I don't want it to be a total turd in the low end. How much will I lose with the longer duration?

I will probably use the Supertrapp.


Offline BVHOG

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #1 on: August 26, 2019, 11:51:55 AM »
First off, sorry but that already looks like a turd in the low end. I have used the very similar Tman 590 in a few 98's with great results but 10.5 would be minimum compression and 10.8 would be better.  The best suggestion I have to ask Wes  himself as he knows the heads and would probably have a great cam to use in this application.
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Offline 838

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Offline 838

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Offline Winston Wolf

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #4 on: August 26, 2019, 02:46:47 PM »
https://harleytechtalk.com/htt/index.php?topic=105628.msg1253699#msg1253699

That engine has 11.2:1.... 

I'm not willing to change anything but the cams.  Maybe the heads aren't that good...?  It has never had much in the low end.  Here is the bike with same heads carb, intake, and exhaust; when it had 10:1 95" pistons, and Cyclerama 575's. 

If there's nothing to gain, I will leave it as is.


 


Offline Barrett

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #5 on: August 26, 2019, 03:18:46 PM »
Did you do a compression test to see where it's at?
I don't know how those cams will respond to advancing but I picked up some bottom end with my 37's going with a +4* crank sprocket for about $50..

Offline 838

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #6 on: August 26, 2019, 03:39:52 PM »
Did you do a compression test to see where it's at?
I don't know how those cams will respond to advancing but I picked up some bottom end with my 37's going with a +4* crank sprocket for about $50..

I was asking just the other day about a +4 on the TR590...?

Offline Winston Wolf

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #7 on: August 26, 2019, 04:43:08 PM »
Did you do a compression test to see where it's at?
I don't know how those cams will respond to advancing but I picked up some bottom end with my 37's going with a +4* crank sprocket for about $50..

205/205 with the TW-6HG.  I don't care if it has the same lower RPM torque as what I have now, I don't need to spin the tire.  I want it to run out as hard as possible when I hammer it.  I understand I can put a huge ugly 2-1 and up the timing so it pings when you roll on it, but I'm not going to.

Offline Winston Wolf

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #8 on: August 29, 2019, 10:22:45 AM »
Maybe Iíll just pull the heads and mill them a little to bump the comp up to 11:1 and try the TW8...

Offline itsafatboy

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #9 on: August 29, 2019, 06:21:18 PM »
So your running the 6HG now , I don't see that much of a diff going to the 8G, just some duration,  what does your timing map look like can you post it , is it a DTT map .

could just bump it to 10.8 and try it with the 6HG , mill a little off through it together and try it,  wonder if the exhaust can be changed up a bit maybe closed end cap and more disks if needed after closed cap , would help lower end,

Offline rhuff

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #10 on: August 29, 2019, 10:01:10 PM »
Something is not right with your setup.  Is it your tune?

Offline Hillside Motorcycle

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #11 on: August 30, 2019, 04:10:22 AM »
After using both of those cams for over 20 years now..........something is wrong.
It doesn't "hit" on the bottom.
The nature of the 6H is all up front, then carry as far as the head will allow.
« Last Edit: August 30, 2019, 04:14:39 AM by Hillside Motorcycle »
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Offline Winston Wolf

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #12 on: August 30, 2019, 05:22:29 AM »
I pulled it apart last night, and I think my memory was off on the details.  Pistons are 9cc dome, .006 down. Heads are 89cc's.  So rerunning the numbers, with the W6HG it comes in at 10.17/9.34 and 189 psi ccc, which is about what my gauge is showing.

I'm going to knock the heads down to 83cc's, which should put me at 10.84/9.63 and 201 psi ccc with the W8G. 

As far as the tune, it's a carburetor, and it's jetted correctly.  I'll probably put it on the dyno again in a few weeks and play around with the lower rpm timing.  I had it pretty conservative below 3500 because I used to ride this bike all over the country and had to take a bunch out for pinging issues. 

I think the pipes I have generally suck and aren't helping things.

Offline rigidthumper

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #13 on: August 30, 2019, 10:50:02 AM »
10.8ish with a W8 is a ripper combo-likes a thin ( .028-.032") squish, cams sometimes a bit ticky, but always pulled hard.

Offline Rsw

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #14 on: August 30, 2019, 11:51:37 AM »
Have the 8g in my 110 set at 10.8cr GMR heads 55 HPI tbody tuned by GMR 134-125. Runs great

Offline itsafatboy

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #15 on: August 30, 2019, 12:36:08 PM »
Ran the 8g in my 116" got 132hp 140tq , they pull real hard nice cam can be a little noisy the closing ramps on cam are fast, 

Offline 838

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #16 on: August 30, 2019, 02:43:40 PM »
I pulled it apart last night, and I think my memory was off on the details.  Pistons are 9cc dome, .006 down. Heads are 89cc's.  So rerunning the numbers, with the W6HG it comes in at 10.17/9.34 and 189 psi ccc, which is about what my gauge is showing.

I'm going to knock the heads down to 83cc's, which should put me at 10.84/9.63 and 201 psi ccc with the W8G. 

As far as the tune, it's a carburetor, and it's jetted correctly.  I'll probably put it on the dyno again in a few weeks and play around with the lower rpm timing.  I had it pretty conservative below 3500 because I used to ride this bike all over the country and had to take a bunch out for pinging issues. 

I think the pipes I have generally suck and aren't helping things.

The new Tman590 (called the 590PS2) looks to fall right in the middle of of the 6H and the 8. I have one stored on the shelf for my next build!

Offline Winston Wolf

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #17 on: September 09, 2019, 05:09:33 PM »
I milled the head's roughly .030 down to 82.5 cc's, and brought the compression up to 10.89:1 by the big boyz calculator. It's cranking over around 205 now with the W8G cams in.  These cams do really clatter compared to the W6H.  I'll test ride tomorrow hopefully.  Timing table is below.


Offline rigidthumper

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #18 on: September 10, 2019, 07:29:21 AM »
Looks good. Here's the one I got from Doug Coffee, for his 10.8 CR/HQ0033 build.

Offline Johnwesley

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #19 on: September 10, 2019, 06:10:33 PM »

Offline itsafatboy

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #20 on: September 11, 2019, 06:48:37 PM »
ya the W8 can be loud , exhaust closing ramp speed , but a really good cam, you can try to readjust the lifters again, but mine were always clattery , timing looks good I think on mine ended up with a 28 deg total advance that other map would be worth a try see if it makes a diff.   

Offline 838

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #21 on: September 11, 2019, 07:17:04 PM »
Is the valve train noise that is associated with this cam the reason it does not get recommended as often as other cams in this class?

Offline Armin

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #22 on: September 12, 2019, 02:07:00 AM »
Quite a number of people have reported of valve train noise when using TW cams including myself. My TW6G were noisy with various sorts of lifters and lifter preloads and now I experience the same with the TW9BG. These cams have fairly steep ramps and consequently shorter valve closing times and thus creating noticeably more valve train ticking.

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Offline Winston Wolf

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Re: Wood TW-6HG vs TW-8G in a 98"
« Reply #23 on: Yesterday at 06:30:40 PM »
Well, bumping the compression and the TW8G made a difference.  Here is the comparison.