of course !!

 

Well I have been saving and it is going to happen in the beginning of 09!!!

 

Quamen, i am waffeling right now on purchasing a T-trim or giving the V+ a try. i know there are alot of different variables involved but i am looking for a generic ansewer. the question is what do you see as the potenial for psi and H.P figures out of this impeller on a built 10.3:1 CR engine running 100 octane with water injection ? reason being is this is the foundation i will be building on but i was planning on installing a t-trim. if this impeller has the same potential i will give it a try. with this impeller being rated for 60,000 rpm i may run the following pulley setup so the boost comes in real early in the rpm band and i will have a pretty beefy tourqe curve for a s/c installation. also through experimentation i may run the boost limiter valve so if the s/c gets to the point of belt slippage i may back the boost off at that point " speculate 16 psi " to take some of the pneumatic load off of the supercharger.

PULLEY SETUP WILL BE
REV-UP ENGINE
SERP=2.87
J/S COG= 34 TOOTH
S/C COG=28

CALCULATED S/C IMPELLER RPM WILL BE (59720.43)
AT ENGINE RPM OF (6800) " THIS WILL BE MY SHIFT POINT "

 

Damn JET - no matter what route you go with the blower, that thing is going to be a beast.

 

where did u get the 60k limit on the impeller from? also its the bearings that fail pretty easily on the vortechs, not the impellers.

plus the t-trim is a physically larger blower. the si already overheats air, not sure why you would think that a higher spun blade would be any better in the smaller housing. get crazy and get a ysi or e trim.

all in all the 6 rib serp is the biggest limitation. thats just goin to be enough traction for that high psi

 

yeah that is what i figured going through the troubles i did with the Si-trim. on 928 motorsports website the V+ impeller is advertised at a 60,000 rpm rated speed due to the impeller being a CNC'ed billet unit and not cast aluminum like the stock vortech impellers. i figured a HD bearing upgrade would handle the high impeller rpm. i am pretty sure the S-trim vortech offers is rated for 60,000 rpm. i will probably end up going the proven route and just upgrade to a T-trim. BTW belt slip will hopefully be eliminated with the 8 rib serp setup i am working on with a local machine shop. " custom made pulleys for supercharger and all accessories".

 

yum, 8 ribs!

that will be sweet. mustang guys use 8 ribs and make some retarded power with t-trims. their blower forums are very active and have alot more info than the vq world

 

The 928M impeller was spun test to almost 70,000 rpms without ripping itself apart.

In regards to the Si trim and the T-trim there is a lot more to consider than just the size of the blower. Vane curvature, inlet area and tip speed play a big role in how effeciently an impeller can compress air. Bearings can be upgraded from Vortech so that allows you to spin it faster.

When I tested this impeller, I did not make more power by spinning it faster. I made more power at the same rpm because of a more effecient impeller which was the goal. Being able to spin it faster was just a secondary benefit.

 

Actually, the reason that this impeller can handle the rpm's is primarely due to the design and not the material or manufacturing process. Things such as self-supporting arches and special radius' can make a big difference in the capabilities of an impeller.

 

I honestly believe that 500whp will not be a problem on a dynojet. PSI is a product of the system so I can't answer wholey other than the impeller should be able to handle whatever psi you can through at it since I would guess your smallest pulley size would put you in the low 20's.

Overall I think that the t-trim is still a great option. I just don't know where the T-trim tops out and where this impeller tops out.

 

thank you for the feed back, it is greatly appreciated!!!!!

 

So, i decided to compare efficencies between the 928m impeller, sc impeller and the si impeller.

Disclaimer to keep in mind is that the 928M V+ and SC impeller #'s musta been done on a V-1 blower compared to my V-3 (based on Quamen's posted impeller speed calc). The volute housing etc is the same size, only straight cut v-1 gears vs helical v-2 gears. Not to mention the huge installation differences between our 2 setups I know my numbers are pretty representative of the street and dyno for psi at given engine rpm.

I went back and put all of Quamen's log #'s into an excel sheet and calculated impeller speed at all the rpms. then compared the amount of impeller revs it took to create the associated boost. the gets rid of pulley size differences for the most part. Did the same with my Si impeller.

Conclusion - that 928M impeller works nicely for low end power. However not much different than the stock impeller. Based on these pulls, the 928M makes more boost per impeller rev up til ~35000. It would be interesting to see data on the 928M pulley at 53000 where i brought my Si up to. It might even keep a steeper slope and surpass the Si.

Now all of this is irrelevant without corresponding hp # at each point, as we all know boost doesnt mean horsepower.

Neat!

 

Just a correction but you ment on a V-2 blower in the first sentence.

Nice graph! My only reason I don't agree with it is that it doesn't take into account things such as:
-Temperature
-Pressure loss in Vortech kit vs. my custom kit
-Other motor work such as cam differences (or HR vs. DE) or exhaust differences which may affect psi
-Altitude difference


Based on those things I would hesitate to say that the graph is an 100% accurate comparison of the Si vs. 928M just as you stated it wasn't. However, it is definitely more than I could provide so it is welcome info.

Thank you for the input and work you put forth!

 

I wish I could have revved it higher like you said str8dum1. With the exponential nature of a centrifigul supercharger I wish I could have seen more rpm's. Hopefully I can soon though!

 

I was goin by this "I just plugged in 6.75 crank pulley/3.25 SC pulley/6500 RPMs (what I stopped at) and I saw 46,575 rpms for a impeller speed. "

That was using the V-1 calculator. Its 48600 rpms with a V-2, so that would your lines down on the chart.

But ya, cant draw real conclusions bc pretty different setups. i'm at 500ft, stock cams, 2.4" td exhaust etc

i just wanted a visual to see how what your output looked like with a $500 impeller.

To bad you cant get a Si impeller to try. If the blowers were more reliable, i woulda spent the extra $150 on the 928m impeller over the Si, just to keep a normal redline.

But with them having to get reserviced so uch, warranty is worth a ton more!

 

I went through the emails I had from unorthodox and founf the emails about the design and I stand corrected. My crank pulley is 6.22 in the rear which is that same diameter as the stock A/C section usually is on a Z. That means I only hit an impeller speed of 44,784 so it is slightly smaller.

Str8dum1- would you mind recalulating? I still think the graph is useful as a base comparison.

Also, what pulley setup are you running and do you know what the stock crank pulley diameter is? Measured to the top of the ribs correct?

 

I just noticed that one of the good things about the curve of the SC-trim and the 928 impeller compared to the Si-trim is that if you are using them on a stock block and aiming for a max psi of say 12psi it looks like both impellers will have much more area under the curve even though they will have to be spun at a faster speed than the Si.

Basically if I would have put the pulley on that would have gotten me the same peak psi I would have pushed that intersect number up even further. Kinda neat looking at the differences between each one.

 

stock crank pulley is 5.75"
so you use a V2 with a 6.22" cp and 3.25" sp?

i will recalc tomorrow. yes from this data, the sc and 928 gave alot more low end. i'd love to get a few more sc logs to plot. that would make a neat study.

 

Yes. I used the V2 with a 6.22 CP and 3.25sp. Based on your logs, it looks like the Si trim will better for peak psi at the lack of low-end psi per revolution of the impeller. The Sc-trim and the 928 impeller seem to have much more low end but need to be spun faster for higher rpm psi.

 

Str8dum1-Ever get a chance to plug in those numbers? i wonder if we could get a boost log from a T-trim.