Help me pick an upper pulley

[myslowstang]

You guys may have talked me into doing a lower pulley. What kind of upper and lower pulley combo do you suggest? I don't have an idler pulley so I may go with a larger upper pulley. Do you think a 2.90 w/ 4# lower or should I go for the 6# lower? Would a 2.90 be ok for an upper or should I go larger?

 

[Posi]

2.9 4lb combo is a great combo and the one that BADASS03SVT was running when he first ran 9's. No reason spending money to switch from a 2.8 to a 2.76 because that's only .020" a side increase and I'm not even sure a dyno would show the gains back to back.

If you do your own port don't skimp on it and spend a lot of time inside the inlet or you'll just add heat and not much extra power if you put a lower pulley on with it. It's going to take you a long, long time to do it and is exactly how I started out.

If you make the outlet larger and then only "polish" the inlet it won't do much at all and you'll be taking a big chance at losing torque. It'll also peak very early in the rpm's too and fall off afterwards. The inlet is the most important part of the port. Be sure and port your stock tb/plenum combo as well.

A port can be done by someone like you very easily but it's going to take some time to do it right. Good luck with it and post some pictures when you're done.

 

[myslowstang]

Why the hell are you asking questions then?!?! Just do it and report back. I swear people's kids:nonono:

2.9 4lb combo is a great combo and the one that BADASS03SVT was running when he first ran 9's. No reason spending money to switch from a 2.8 to a 2.76 because that's only .020" a side increase and I'm not even sure a dyno would show the gains back to back.

If you do your own port don't skimp on it and spend a lot of time inside the inlet or you'll just add heat and not much extra power if you put a lower pulley on with it. It's going to take you a long, long time to do it and is exactly how I started out.

If you make the outlet larger and then only "polish" the inlet it won't do much at all and you'll be taking a big chance at losing torque. It'll also peak very early in the rpm's too and fall off afterwards. The inlet is the most important part of the port. Be sure and port your stock tb/plenum combo as well.

A port can be done by someone like you very easily but it's going to take some time to do it right. Good luck with it and post some pictures when you're done.

Awesome! Thanks! Yeah I may go with that combo. I'm giving myself lots of time to do the porting and only going to take a little off at a time. If I'm not happy with my home port job I'll be sending my blower (or a replacement one lol) your way.
Thanks again for your help!

 

[timspony]

...On the dyno, the HP was the same between the 2.93" & 2.76" upper with the 4# lower...however, the 2.76" had 10 ft/lbs of torque over the 2.93" ... So, I stuck with the 2.76" upper!!

I'm sure at the track there would be very little difference between the 2 upper's

 

[Posi]

Awesome! Thanks! Yeah I may go with that combo. I'm giving myself lots of time to do the porting and only going to take a little off at a time. If I'm not happy with my home port job I'll be sending my blower (or a replacement one lol) your way.
Thanks again for your help!

Just don't get to crazy with your outlet size on it and you'll have something that IF someone needs to finish it they have something to work with. When we finish a Home Port typically I don't touch the outlet and it's all inlet work. Every once in a while though someone goes huge with the outlet and then I have to tell them to retire the case. That's not fun to do at all.

Good luck with it and if you go into the Terminator How To section there's a thread in there for exactly this that people post in.:beer:

 

[nycarpenter]

So you trust a pizza box more then yourself? lol That's sad

Like I said a port job cost $500+ if I send it out for someone else to do. If I port my blower myself (even if only half as good) and add a lower pulley I'll get more hp and tq with less cost so why not try to port the blower myself?

Doing it myself is cost less + more power (with money saved for lower pulley) + the experience of doing it
vs paying someone to do it and costing more and getting less power. What the advantage of having someone else do it?

Why are people so scared to try to port a blower?

Sad? Scared? I ported my own eaton it laid low 500s on an upper 2.8 pulley on a 90 degree day This was not my first port I have done a few for friends in the past 6 months but have all the tools bits compressor etc. I suggest Brian at Posi to anyone as his ports always produce and I think for $500 it's worth it. The lower pulley costs $400 alone. IMHO would rather have the stock lower a real good port and a 2.8 2.9 upper. Your posi port will hold value while the home port will bring nothing over a stock eaton. Trust me somewhere down the line it will be up for sale when the twin screw, TVS or turbo bug comes along. Not trying to pick a fight just saying it is something to think about. Good luck with whatever you choose P.S Brian ported my first Eaton which I sold for $725 and put the funds towards the purchase of my first Whipple

 

[myslowstang]

Sad? Scared? I ported my own eaton it laid low 500s on an upper 2.8 pulley on a 90 degree day This was not my first port I have done a few for friends in the past 6 months but have all the tools bits compressor etc. I suggest Brian at Posi to anyone as his ports always produce and I think for $500 it's worth it. The lower pulley costs $400 alone. IMHO would rather have the stock lower a real good port and a 2.8 2.9 upper. Your posi port will hold value while the home port will bring nothing over a stock eaton. Trust me somewhere down the line it will be up for sale when the twin screw, TVS or turbo bug comes along. Not trying to pick a fight just saying it is something to think about. Good luck with whatever you choose P.S Brian ported my first Eaton which I sold for $725 and put the funds towards the purchase of my first Whipple

That's my point. We all have to try it to know now to do it. Nobody was born with experience on how to port a blower. You are right about a lower pulley costing as much as a port job. Lower plus an alt pulley plus a new belt... I'd be spending more on pulleys then I would on a professional port job.

Maybe I'll just stick with my current pulley setup and port it myself just to see how it works. That way if I mess up the blower I'll just find another used one and just slap it on there.

I'll have to give this some more thought....

 

[nycarpenter]

That's my point. We all have to try it to know now to do it. Nobody was born with experience on how to port a blower. You are right about a lower pulley costing as much as a port job. Lower plus an alt pulley plus a new belt... I'd be spending more on pulleys then I would on a professional port job.

Maybe I'll just stick with my current pulley setup and port it myself just to see how it works. That way if I mess up the blower I'll just find another used one and just slap it on there.

I'll have to give this some more thought....

Take your time always be aware of the thin spots in the case. The inlet is the big power gain and I spent hrs in there but after it was all said and done the blower made good numbers. Try the upper only and a good tune. It may surprise you and if its not enough go for the lower. I skipped the lower and went to a whipple but everyone is different... Good luck with it and read Posi's how to port your own blower thread. I got half way through the thread then just called him and drove him nuts

 

[myslowstang]

Well guys I ended up going with a Posi port instead of doing a home port with a lower pulley. I figured the cost of a lower pulley with a home port will cost just as much, if not more, then sending it out to and having it done professionally. I haven't made up my mind about the upper pulley... I may stick with my 2.8" but will most likely try the 2.65" and see how that works for me.

Thanks for the help guys and I'm looking forward to seeing my Posi blower!

 

[myslowstang]

Just wanted to update you guys that are interested. My Cobra made 518rwhp/497rwtq with all my mods. No belt slip with the 2.65" and it fits tightly on there with a 100mm idler pulley. I'm happy with the car!

Thanks for the help!

 

[Senkak]

Just wanted to update you guys that are interested. My Cobra made 518rwhp/497rwtq with all my mods. No belt slip with the 2.65" and it fits tightly on there with a 100mm idler pulley. I'm happy with the car!

Thanks for the help!

Nice numbers!
You are happy with the car for now.
It won't last.
What's next??

 

[myslowstang]

Lol. Yes I'm happy with the car. Next will be some cooling mods, tires (for the track), and some suspension stuff. I haven't been to the track with the new set up yet but before I did all these modifications I was having problems getting off the line. I was getting a lot of wheel hop. At that time I only had an 2.8" upper pulley making (408rwhp/415rwtq) and ran a 12.8 @ 118mph lol. I'm new to the IRS world so I sure that had a lot to do with it. I need more practice launching... once I get it down, game on!!

 

[myslowstang]

I forgot how much boost it made but I'll post the dyno sheet later

 

[myslowstang]

Here's the dyno sheet
518rwhp/497rwtq
made 14#s of boost