Upgrade Time..T or YS?

**eades5.0** · 09-24-2005, 02:14 AM

Well I've been running S-Trim for over 5 years, and it finally is time for a rebuild, but also the perfect time to upgrade.
The current combo is
331 8.5 c/r
TFS TW 2.02s (300/230)
Cam Motion Custom (564/239/114)
Port matched Holley systemax
1 3/4 LTs
S-Trim 13psi
60lb injs, dual 255inlines, -8feed, -6 return (in work)
Alky inj
TKO600

The car made 588rw on 13psi running outta fuel at 5400rpm (on the 42lb injs and stock lines rails)

Now I was only making 13psi but spinning the S-Trim for all its worth...I ran a 2.75/7" which obviously was over spinning the S.
I'm sure you all are aware of the CFM ratings of the S/T/YS....and the reason I'm leaving the YSi out is Vortech doesnt rec. it on a curved volute (kills eff. they said) and said the YS performs better on the curved discharge.
This car is a weekend cruiser/drive on nice days to work or whenever I feel like cruising..I'm looking for a blower that will give me room to grow, and I wont have to spin it so hard. Looking for 15-18psi w/o even thinking twice, and obviously some nice CFM.
S-Trim 1000cfm 50,000 max impeller
T-Trim 1200cfm 55,000 max impeller
YS-Trim 1600cfm 65,000 max impeller

And yes this car is driven on the street 98% of the time
My goal is mid 10s

Thanks
Chris

**eades5.0** · 09-25-2005, 03:12 PM

bump

**Pro Stock John** · 09-26-2005, 08:41 AM

I'd upgrade to a T-Trim, I'd go to the YSi if you were looking to go mid 9's. T-Trim is good for over 700rwhp at a minimum.

**BLOWNBY** · 09-26-2005, 11:08 AM

Second that plus the T is easier to install since it is smaller. You will need to upgrade to the mini race bypass as well. Mondo is not necassary but will work as well. The mini is just smaller and cheaper.

**eades5.0** · 09-26-2005, 11:48 AM

Thanks guys

**Redsnk95** · 09-26-2005, 05:04 PM

I still say the T-trim.

Troy

**tomcat** · 09-26-2005, 07:44 PM

Vortech has a neat compressor map on their site that compares the efficiency of the S and T trim. But to make a decision you need to know where your engine's total system resistance lies on this map. You already know two points on this curve and it's easy enough to draw a curve between these two points.

Based on your numbers, you are spinning the S-trim at about 47,500 RPM. If the belt is slipping deduct 5% from this number for 45,000 RPM. Intake boost is 13 psi but add 3 psi for losses through the ducting etc. for a pressure ratio of ~2.1. I have no idea how much to adjust the rwhp so I'm going to guess at 700 HP crank. That's about 70 lb/min of air flow. This defines the upper point of the curve. The lower point of the curve is basically (0,0).

I marked up the compressor map and attached it. You can see that the S is running about 66% efficiency at your WOT operating point, where the T would be about 72%. More important you can see by extending the system resistance curve up to a pressure ratio of 2.4 you would gain about 100 HP. The curve is steep, so it's very much diminishing returns.

The real answer is to make the curve less steep. You do this by installing better cylinder heads and a bigger cam. Then you need the YS, because you will be off to the right of the efficiency islands for the smaller blower.

**Pro Stock John** · 09-27-2005, 08:38 AM

The YSi can make over 1000hp but it would be overkill for low 10's unless your car is 5000 lbs. Plus the piping will have to be 4.00 in diameter.

**BLOWNBY** · 09-27-2005, 08:51 AM

Your car will rock with the T and make some serious power. I wouldn't be suprised if your at least mid to upper 600's at the tire.

Oh and I'd get the 8" 10 rib setup as well. Just so you don't have to worry as much with belt slip.