vortech JT trim

[96snake719]

any idea how to figure that out? vortech doesnt have a V7 calculator? is there a big difference

 

[96vertsnake]

You can call or email Vortech. If I recall, when I asked them about my YSI they said to use the V1 calculator. Also take a look at this website.
Vortech Impeller Speeds

My experience is that your motor and headers will determine boost. I was running the 2.70(smallest available)blower pulley with stock balancer and seeing 14-15 psi on my YSI set up(see build in sig and numbers are with this pulley combo). I had the car tuned to either 6800-7000 RPM and stopped there because I ran out of fuel with 60lb injectors.

I had an 18% overdrive balancer "laying" around so I put that on. I'm now making 19-20 psi with the same 2.70 pulley but I haven't hit it yet because I'm not tuned and I need 80lb injectors.

Using the V1 calculator from the site I posted I'm seeing 69,319 rpms at 7000rpm's. (7000rpm x 3.45 step ratio x 7.75 crank pulley/2.70 blower pulley) <Max for YSI is 65,000rpm's, but I won't be there too long so I'm not worried about hurting it.

 

[98 Saleen Cobra]

Yea I"m pretty sure that you use the V-1 calculator as it's the same step up ratio. IIRC off the top of my head the 10% O/D and like a 3'' pulley make around 55k rpm.. Depending on your head, cam, and exhaust setup you would need a smaller pulley or bigger pulley for pump gas.

 

[96snake719]

thanks for the info guys! I used the V1 calculator and with a 2.95 and 7000 rpm it says a hair over 59,000. The 3.12 is 56,000 it says the max impeller speed is 60,000. So what would you go for the 2.95 or the 3.12? narrowed it down to those two.

 

[98 Saleen Cobra]

What does your head and cam and exhaust setup look like.. I'd personally do a 3.12 to be safe for pump gas.. Then you can run the proper timing.. That should put you around 18 psi depending the stuff above mentioned?? Maybe more.

 

[96vertsnake]

It will all depend on how much boost you make with either the 290 or the 312, however, I wouldn't worry about over spinning the blower by a few 1000's rpm's at 7000 rpm's. The JT has the heavy duty bearings. Unless you're building a drag car you won't see 7000 rpm's for more than a fraction of a second and on the street thats just when you have some spirited runs.

 

[96snake719]

heads are stock, ported with comp stage 2 blower cams. Exhaust is JBA shorties o/r x and 2.5 inch mac catback. Yea Im honestly thinking the 3.12 is gonna be the one to get give me just a little bit more belt wrap aswell! thanks guys

 

[98 Saleen Cobra]

3.12 your poor exhaust lol.. Thing needs some Big LT's and a 3'' exhaust.. hahahaha.

 

[96snake719]

3.12 your poor exhaust lol.. Thing needs some Big LT's and a 3'' exhaust.. hahahaha.

haha I know! I was gonna do longtubes but the thing sits so low i was really worried about them. I no Im gonna ditch the macs for a set of straight throughs like magnapacks or somthing.

 

[96snake719]

ok I finally got all my 8 rib pullies, and my 10 % OD crank and I found a 3.00 inch high traction blower pulley on vortech that I ordered. So just a hair smaller than there standerd 3.12 I think it is. Hmmmmm now I wonder what kinda boost and power numbers Im gonna see with this combo lol.

 

[98 Saleen Cobra]

Well I had a 3'' blower pulley on my T-trim and stock crank pulley and I saw 17psi right at 7k rpm through my LT's and 3'' O/R exhaust. I'm going to say you're going to be making way to much boost for pump gas lol.. Factor in the smaller exhaust, more CFM the blower is producing and the 10% O/D.. Just make sure you have race gas in there for when you tune it.

 

[96snake719]

does that mean I have to run race gas on the street aswell!? this is a pure street car and I drive it A LOT in the summer that wouldnt be to practical for me lol

 

[98 Saleen Cobra]

Yea pretty much. You need a bigger blower pulley lol. Probably around a 3.33'' and it'll be able to be ran on pump gas.

 

[96snake719]

what are the typical horsepower limits when it comes to pump gas? and now Im wonderin if my 60 lb. injectors will be enough.

 

[98 Saleen Cobra]

It's not about HP limits for fuel, its about the amount of boost you can run safely.. IMO on 93 octane you dont' want to run more than 18psi.. and probably around 19degrees of timing or so..

 

[96snake719]

I really dont think Ill be at 18 psi (I could be wrong though), my set up right now is just squeaking 12 psi, and thats with the S trim and 2.8 inch pulley through the aftercooler. Ill be runnin the JT through a big treadstone intercooler so boost that the OD crank picks up will prolly be soaked up by that anyway.

 

[98 Saleen Cobra]

You won't lose as much boost as you think through the intercooler maybe 1.5psi. The JT trim flows more CFM per blower RPM than a S-trim does. more CFM means more boost. But every setup is different. I'm just lettin ya know you might be over the limit for pump gas, and when you go and get it tuned make sure you monitor what the boost is doing..

 

[mtrsprt]

I had the car tuned to either 6800-7000 RPM and stopped there because I ran out of fuel with 60lb injectors.

How do you figure you ran out of injector??? :??:


The V7 uses the V1 gearcase, but with heavy duty extreme bearings.

The JT will move more air at the same impeller speed than a YSi and be easier to spin.

The JT is no joke.....

I am swapping out my YSi for JT-trim shortly.....

(This is on a 2V yes)...