I took my mostly stock 2000 T-cat to the dyno on Saturday for some clutch tuning and while I was on the dyno I checked my air box restriction. The mods to my t-cat are air box gutted, 2 degree timing key, heads milled .010, V-force reeds, tempaflow installed, everything else is stock. I tapped a 1/8 pipe fitting into the airbox and attached a vacuum gauge that reads inches of water and watched it while the dyno pulls were performed. To my surprise the vacuum gauge only read 4 inches of vacuum at WOT. Atmospheric pressure is 408" of water so a vacuum of 4" is very low. What this tells me is that the stock airbox opening are not very restrictive on this sled. I was debating adding a power breather but after seeing the numbers I am going to skip the power breather.

Now for the track dyno numbers. I hesitate to post this because most people who have never been to a track dyno do not understand why the power numbers are so low. A rule of thumb is that you only see 1/2 the engine power at the track so a 100 HP sled will only show 50 HP at the track. After dynoing my sled I believe you see more then 50% but I am not sure what the real number is until I get my engine dynoed. When I was all done my T-cat pulled 98.5 HP at the track which according to the dyno operator was very good considering the small mods that I had done. He claimed most T-cats pull between 85 and 88 HP at the track and he was very impressed with the 98.5 HP that mine pulled, that made me feel good!

My final clutching combination was 67 gram weights with a 165/320 spring and a 62/57 helix and a very strong black secondary spring rate unknown. The engine did not like to rev higher then 8200 RPM. Every time we pulled it higher it lost power so we kept it at 8200 RPM and that is where it pulled the best numbers.

Thanks for info, yeah I have a power breather was on mine when I bought the sled but you are better off guttong the inside back or drilling less carb noise, I will put stock top back on mine, glad to know where your rpm`s are. You could have added a 3 to 4 degree key, I have a 01 T-cat are boxes according to all at the cat race dept are simillar, & it wouldnt hurt to add 4 degrees. Also if your not ported or case ported, you should add a .250 reed spacer will gain 5 hp with v-force.

Thanks for the comments, I do have reed spacers but I did not put them in, that would be interesting to try.

I have read that spacers will not help on cats... they only help on the yammer tripples... some say its a waste of money...

BM

yup just talked to dale @ D&D said dont use them, sorry.

What timming key should I use 2-3 or 4, AL @ cat race said 4 Dale said 2 ?

What jets are you guys running in the 01 T-cats ? I havnt had mine apart yet!

2 degree, I was just talking to Arnies Cat house , and Arnie said Two degree. :div20:

Thanks for the info I just assembled my engine and I went with a 2 deg key reeds are next,So ill forget about the spacers then I did add 4 bulls eyes to the front of my air box 01 t-cat

Exactly. Yammy triples have 2 reasons for the spacers, 1: the jug hangs down in front of the reed cage, so moving the reeds back and removing 1/4" from the bottom of the sleeves will allow the mixture past the obstruction. 2: yammy's have small bore carbs that work off 'velocity', so lengthening the intake tract builds torque. Boring yammy carbs is a no-no, unless you are racing and running WOT all the time.

Anyways, back on topic!! :beerchug:

62/57? Is the second number correct???

Yeah I would say 62-52.

I would say this doesn't take spinning into factor but Mine spins bad My friend just bought an apex gt. I raced him in his field and was beating me in 1000 feet. I was a little pissed about it but after driving the apex I can see why out of the hole its really fast but doesn't have the legs. Mine spins so bad he was destroying me outta the hole I have about a thousand miles on the track and studs (stock track) no good but it seems traction is a big part of it i run stock gearing and a different clutch kit but that apex is pretty good. I am impressed, I don't know what to say but I definately could use am apex killer clutch kit.

kirbytown what sled do you have

Clutching will also affect track HP #'s quite a bit. You may find that the engine dyno may show closer to 175-185hp. Do not be dissapointed. Most T-cat 1000's with airbox mods,pipes and reeds dyno in the honest 174-180hp range.

I agree with you on the HP of my engine. I am guessing I am between 175 and 180 HP.

Someone else asked about the helix it is a 62 start and a 57 end.

I have not driven this combination on the snow yet, there may be some fine tuning that needs to be done to make it work on the snow.

Ideally a helix that is straight or very close in angles will produce the most power. Very nice that you found 62-57 to work!!

how could you watch a guage inside your airbox without having it open to see if there was any restrictions and you also have to remember you dont exactly have as perfect a vacum as you wish you could to get the truest readings.

Most likely able to run a 62/57 due to the stiff sec spring.,,jmo. snap

I taped the side of the air box and ran a hose to a gauge mounted outside of the hood to find my airbox vacuum level. The vacuum gauges I used are very sensitive (and very expensive magnehelic gauges) and are able to read in 1/10 of an inch of water.

Brian

cool sounds good to me still debating on usings uni's or not o well who knows