DeltaT

iTrader: (5)

I just finished this upgrade and started some testing, but so far I'm seeing about the same boost with the T-trim as I used to get with the S-trim, around 7# after the FMIC.

Questions:

Does the T-trim need to be spun higher than the S?

Did you notice that your belt needed to be a lot tighter on the T?

Any belt slippage issues on the T?

Anyone tried the Vortech "Hi-Traction" pullies? Results?

Any other information or tips on this swap appreciated.

The car is running great, but I am hoping for a dramatic difference for the money. I've got 5 gallons of 100 in there now for tuning, and I just swapped from a 3.12" top pulley (got a 7" below) last night to a 2.95" Hi-Traction one, but haven't had a chance to try it until tonight.

Thanks,

Jim

engineermike

The Vortech compressor maps show the S and T trim to produce the same boost at the same compressor speed and same flow. The difference is in the efficiency, where the T-trim is more efficient over a boader and higher flow/pressure range, especially around 15 psi boost and high flow, where the T-trim picks up about 7% over the S.

Mike

DeltaT

iTrader: (5)

I don't see where this agrees with what you are saying, but maybe I'm reading the map incorrectly:



The S-trim is rated to 680fwhp, and the T is rated to 825fwhp.

Thanks,

Jim

engineermike

In that graph, the orange lines are the boost vs. flow vs. compressor rpm curves. Notice how there are not 2 sets of curves. The same set applies to both compressors (unless I'm interpretting it wrong). With the same compressor curve, you get the same boost at the same airflow when you turn the compressor the same rpm. However, there are 2 sets of efficiency islands, which show where the T is superior.

This tells me that the impeller OD and volute shape is the same for the S and T trim. The T trim, however, has a bigger inducer, allowing more flow and more efficiency at high flow, without increasing boost.

Mike

DeltaT

iTrader: (5)

So how should I translate this into the additional power I expected? I just tried the slightly smaller pulley - wow, switched from 6.66# to 7.68# - I was hoping to go from 7# to like 11#, and I'm not seeing the payoff yet.

I do have some belt rubber which I haven't seen in a while, and datalog indications that I might be getting some slip.

Thanks,

Jim

PS Are you saying I might be making better power with only minor measured boost changes, because of additional airflow?

DeltaT

iTrader: (5)

Any other input?

Thanks,

Jim

engineermike

I'm saying that you'll get more power at any given boost level due to the increased efficiency. The T-trim will be most efficient at high flow in the 15 psi range. The efficiency will get you cooler IAT's and less power to drive the blower. Mine made good power at 13 psi. I tried spinning it faster but just got belt slip even with the Reichard pulley.

DeltaT

iTrader: (5)

Well, I'm (slowly) going in the right direction. Tightened the belt even more on a hi-traction pulley. Hit an all time hi boost mark of 8.7#, so I am still not seeing the magical hi-efficiency zone. Still seeing some belt dust on the 8-rib.

It feels stronger all around, but I'd sure like to see a solid 10# out of it.

How tight did you used to keep your belt, Mike?

Here's a datalog of my best run yet. Peak boost at 5629rpm, then it drops off a bit.



This is where I think the belt is slipping, because the line should keep going up, as opposed to dropping a bit and stabilizing around 7.4#. Frustrating, but maybe I need more serious bracketry, and a better tensioning system.

Thanks,

Jim

eb02z06

iTrader: (18)

In my experience the T-trim likes to be spun hard to really shine as the S-trim is one damn good blower. When you tighten belts do it over a few days of driving or track passes. So don't go and tighten the crap out of it all at once. Tighten so it's snug-drive around for a while to get the belt hot-loosen it and do retighten it. It usually take around 3-4 of these tighten loosen procedures before the belt get's really snug.

engineermike

Nothing special, just a stock Vortech (Ford) F-body tensioner.

Mike

2001WS6Vert

Delta, what size motor what heads, exhaust and how wild is the cam?

DeltaT

iTrader: (5)

OK, I just updated my last post with a datalog.

Motor is a 383 with ported Edelbrock E-Tec 200 heads, ported Holley 950 single plane, solid roller cam (230/236, net lift .600/.603", 112LSA), 9.6:1, big Bell FMIC, 72# RC Eng injectors.

Exhaust is custom fitted 1 3/4" Hedman Husler longtubes, true dual 3" system with a 3" H-pipe.

The belt on here is broken in pretty well, and I have a special pulley I bead-blasted (so it's rough) and then had hard-anodized. My belt is pretty tight, and I have excellent wrap around the drive pulley. It is possible that the crank pulley needs roughening and hard anodizing.

Please check out my site to see details - lots of pix there and closeups.

Thanks for all the suggestions - keep them coming.

Jim

My Site: http://home.mindspring.com/~jim_fisk/id1.html

2001WS6Vert

Wow, just looked at your sight, you've got something a little different there. The graph does look like it might be slipping, tailing off so early like that. What does the butt-o-meter tell you? Any dyno comparison? For the first time I am having slip problems since going with the YSi. I did put on the Reichard pulley which seemed to help. Now my trans. is going out again so I'm in Limbo until I get that fixed.

eb02z06

iTrader: (18)

That's what my graph looks like when the belt slips-how much belt wrap do you have?

DeltaT

iTrader: (5)

Belt wrap is good at almost 200 degrees:




Tightening could use some more aggression, but before long I will wonder how much is too much...

Also I am considering recreating my current aluminum front-mount blower plate with a steel version for stiffness and rigidity. Ideas?

Jim

JMBLOWNWS6

iTrader: (17)

I had more belt wrap than that and was running 12 to 13 psi. My my old t trim ramped hard and fast over the g trim

2001WS6Vert

I know some people don't like the Gatorback belts. Maybe try a Gates belt and a Reichard pulley.

405dave

I would like to make a suggestion. I believe you are running too long a belt. Is it possible to go from the blower straight to the crank pulley using one tensioner? In good air my S-trim would put out 12-14 pounds (302ci) with no slip on 8 rib belts (gates). I think you might have a belt whip problem due to the lenth.

DeltaT

iTrader: (5)

Good suggestions everyone, thanks.

If I change the layout of my tensioner I could run a belt direct to the crank. If I do it now (I have tried), it twists the tensioner because it's being pulled sort of across its axis where it is not as strong.

I can do this and report back.

Thanks,

Jim

kp

iTrader: (34)

It sure looks like its slipping from the graph, sandblasting the pulley will help for a while if everything else fails. Doesnt last long on a street car though.