Whats going on guys, I just wanted to share my Vortech numbers from Function Tuned. I previously blew my built engine at just over 4k miles spinning my bearings; I blame the non rev up oil pump for that; anyway, I ended up going with another built block and ditched the ss box. Dave suggested we go with Osiris as it would help the car operate more like stock. After a couple hours of tuning on a DD, I managed to make just over 400whp and 370wtq. I am very happy with my numbers and Dave tells me there is more to be made, just need to upgrade the intercooler and/or bumper. It’s my understanding that a dynojet would read higher putting my numbers at 440 or 450ish…

I will be going back to FT for all of my tuning as Dave and Ken seem to really know what they are doing. If you’re on the east coast you should def consider taking your car there. By the way, I drove down from NY and they took care of me quickly.

 

nice numbers!

ya, you can build up more power with them on the stock intercooler but the problem will be fuel. Mine pulled 451hp on Injected's dd and that was the limit of a single walbro. The superchargers eat a lot more fuel.

To get over that you'll need twin pump or meth. If you're built then rev that beast to 7100rpms to get some more pull on the top end. It'll make a big difference.

 

Thanks man, yeah fuel was an issue at first so Dave added the JWT FMU along with my walbro. Im actually really suprised with the torque though, I thought it would dyno a lot lower.

 

350tq isn't bad. That's about normal.

what boost pressure were you seeing with that 928 impeller and what other mods did you have? I was full built engine, heads, cams, headers, exhaust and a return fuel system.

 

nice numbers! the Z must be a blast to drive now!

 

Isn't SC supposed to built tq all the way to max power? Just curious why the tq drops off like a turbo.

 

builds hp to max. torque will always drop off in a car because the faster the crank is moving the less tq is placed on it.....well, that was kind of a crappy way of putting it but that's the best i can put it to words. someone else?

 

Lol, you know more than I do on that subject, but in regard to my build I have 8.8:1 wiseco pistons and eagle rods. Im making just past 12 pounds of boost at redline which was moved up to 7000rpm. I would love to get cams but that will have to wait for now, didnt have the money to purchase them at the time of the rebuild.

 

What blower has the 928? Is that the V2 T-Trim or is it an older unit?

<--- Still trying to figure SC's out.

 

what headers/testpipes/exhaust do you have on that? With my headers, test pipes, and true dual exhaust I was getting 14psi on my Sc trim with the stock impeller. That 928 impeller should be putting down more boost. Some other user had one on here and was putting a good deal more boost with that impeller.

Is there a chance you might have a boost leak somewhere? I know every car is different but for you to be 2 psi lower than mine when your impeller should actually be more like 2 psi higher than mine is kind of odd. I even have ported heads and cams so mine should flow more which means lower backpressure (boost).

 

Binder, thats a very good question, I expected a lot more boost with my set up. Right now im on stock headers with berk test pipes and an xo2 exhaust. Before I had the 2.87 pulley and 928 impeller I was making about 9.5 pounds which is normal. I expected roughly 2 pounds from the 2.87 which would bring me up to around 11.5, the 928 impeller is said to deliver about 15% more boost which would drive me up past 13 pounds...I will see if I find a leak, most likely in the intercooler, because trust me I made sure that everthing was TIGHT.

Ruthless, the 928 impeller is made by an aftermarket company specializing in porsche rebuilds I believe, they make a performance impeller for the vortech sc trim which delivers more boost than the stock impeller throughout the entire rpm range. It is not made by vortech.
http://www.928motorsports.com/parts/...h_impeller.php

 

9lbs on 2.87 isn't normal.

I was seeing 11.5lbs on 2.87 at stock redline with all my free flowing mods. Stock headers should let you see a higher boost since the backpressure is more.

Each car is different so maybe that's your car but truthfully you should be in the 12lb range with a 2.87 and stock impeller. That 928 should put you over that.

 

I should clarify; with the 3.12 pulley I was making 9.5 lbs. I added the 2.87 and 928 together so I cant tell how much the 928 added but I would guess it was a little more than a pound. I thought it would add more but as you said maybe my car is just different.
I was looking over my boost curve and it plateaus at around 10 pounds across 1k rpm from 5k to 6k. Above 6k it keeps increasing until it hits just over 12lbs. I thought it meant my belt was slipping but I didnt hear a squeal. Is that typical?

 

belts squealing is SEVERE belt slip. Belts slip long before it makes noise. You shoudl NEVER have a flat spot in a boost curve on a supercharger. Every rpm that engine goes up the boost will go up. It's directly tied to rpm of the motor through that pulley.

Pulley's add about 2lbs per size so if you were 9.5lbs on 3.12 then you should be at 11.5 on the 2.87 stock impeller. The 928 impeller has shown quite a bit higher boost levels than that. You're 3lbs down from what my car was doing on a stock 2.87 pulley. That's just weird. The flat spot on your boost curve would mean belt slip or boost leak somewhere.

 

hmm, you're on 8.8 wiseco pistons. I'm on 9.5. I wouldn't think it would make THAT much difference since i kept my boost numbers pretty high when i went from stock block 10.3 to a 9.5 lower compression. Just figured i would throw that out there as possibly a reason for lower boost numbers.

the flat spot in the boost is still an oddity.

 

If I could call it based on the dyno plot I'd say you're slipping above 5.5k. That could also explain the lower than usual peak boost and HP.

 

Thanks for the input guys, my hp curve seems to be flattening out right after 5200rpm or so. Im thinking this has to be the belt slipping as well. I have the GTM pulley mod so hopefully all I have to do is tighten the belt with the tensioner.