Who knows what the diameter of Crankshaft Pulley JET-90108
http://www.summitracing.com/parts/JET-90108/

I doubt anyone will know that, probably best to contact the manufacturer, or if summitracing sells them you could probably ask them.

Who could ask summitracing??? it is very important

or this http://www.summitracing.com/parts/ASP-541800/

I want to make myself an aluminum Crankshaft Pulley

You could, just go on their site, see if they sell them, and if they do, either call or pull up an online chat. I've done stuff like that a couple times when I wasn't sure about something they sold, hell, their product description might have it even.

Auto Specialtie:
Underdrive Percentage 25 percent

JET Performance:
underdrive pulley kits add 10-13 HP

I have not found information on the size!

So ask them, they'll probably be more than happy to pull one off their shelf and measure it for you, but I'm not gonna ask them for you..

I wrote a letter!
Waiting for an answer!

Just think what they did not answer my question!

Well idk why you did that, that could take a while, just chat with a tech online, or call..

My English is at zero!
I live in another country, I am very expensive to call

I have a 25% crank pulley from ASP. Just measured it, and it's exactly 5 inches, 127 mm, edge to edge.

JET Performance:
underdrive pulley kits add 10-13 HP

on a perfect day??? Still doubtful, as I had them on my stock 3.1L. Mabey on a really modified V6 thirdgen though youd get that.

Pulley hand made Ukraine

Power gains from under drive pullies are vastly over-rated. Real world.. maybe 2-5 HP but that's also about the variance you'll get between dyno runs anyways.

Anything custom like that is badass. You have something no one else has. Nice work.


I agree, but they do help a bit. I think the variance is perfect conditions. Like flex fans. Everyone lists them as a 42 hp gain because Car Craft happened to dyno that hp gain about 10 years ago. But their Mustang also used a different t-stat, water wetter, and so on. Now every idiot thinks they'll gain 40+ hp, when it's really more like 20. Same here. Under some odd conditions, a pulley set probably does pick up 13 hp. On our engines? Nope. My dyno says it was good for 5 or 6.

Agreed. I got them a few years back and my 1/4 mile times really didnt any faster at all. Mabey a solid .005 on average. Whats that 5hp.... after that I stoped getting bolt on stuff for mine and saved up money for parts that were worth is. You can get a cam kit from delta for 100 bucks. Theres a good 10-15 hp. IMO thats the way to start your car off right.

I want aluminum pulley, but it did not make the stock size!

waste of time for HP, if for looks id give it a pass.

make sure an order a new ARP crank bolt.