[Fast4Eye]

They're confusing crank for crank pulley. Buy the balancer you can afford, powerbond, romac whatever, upgrade to the to the 1 piece vortech pulley, 8 rib set up. 6.87 should do fine for what you're after.

FWIW I used my stock balancer for years with a 8 rib Si with no problems.

ok bought the power bond and definitely going to the one piece pulley. I just wanted to know if it was worth going to the 8" renegade pulley or whatever its called because I've seen guys on forums say that it reduces the lag for boost to build, so of I'm already spending the money, may as well buy the best pulley I can get for said money.

 

[SNK VNM]

Reduces the lag for boost? If you want more psi sooner, pulley down or switch to something other than a centrifugal aka turbo or tvs style blower.

 

[Fast4Eye]

Reduces the lag for boost? If you want more psi sooner, pulley down or switch to something other than a centrifugal aka turbo or tvs style blower.

I wasn't planning on completely switching the kit lmao

I've simply read that the 8" crank somehow reduced lag so I figured if I was spending the money on a pulley kit, I'd go that route.

Would it be a good idea to use the 8" crank and a 3.33" blower pulley? Probably less likely to slip and lots of head room in the future for more boost I'd think.

 

[SNK VNM]

How much boost are you wanting? 3.33 and 6.87 won't have any slip. Search here and you'll likely find different pulley configurations and the psi they made.

Keep in mind boost is simply a measurement of resistance.

 

[Fast4Eye]

How much boost are you wanting? 3.33 and 6.87 won't have any slip. Search here and you'll likely find different pulley configurations and the psi they made.

Keep in mind boost is simply a measurement of resistance.

I understand that everyone's setups are different so 7 pounds can make like 400 on one car and 280 on another. I don't have a baseline so I don't really know how much boost I'd want, but I guess I'd want as much boost without blowing my head gaskets or headers off. Would 12#s be safe or is that over the top?

 

[Fast4Eye]

Side note, if I have to buy a new pulley pack anyways, should I just go 10 rib? What problems could that possibly bring about, do I need an E-fan if I go that route?

 

[Dwain]

The 8 inch lower pulley will allow you to run a bigger pulley up top which equates to more surface area contact between the pulley and the belts. You can run less tension with larger pulleys and not have slip. You just need to ensure there is a pulley combination that will get you where you want to be regarding boost. I have an 8 inch lower pulley but I dont remember what the upper 8 rib pulley is any more. I would have to go measure it. I dont know how much available space there is and if you can get away with a 10 rib pulley without converting to a low profile electric fan. I am pretty sure the 8 rib fits without any modifications. YOu can probably find some old thread on here with 10 rib setups and if they are still using the stock shroud and fan.

 

[SNK VNM]

Your car is a stock 86 with a cobra intake correct? I made 13 lbs @ 61xx rpm on a bone stock 91 with h pipe and catback using 3.33 and 6.87 on a v3 si with heritage gears and upr power pipe(lower step up ratio than the standard helical gears). You could use the standard 8 rib ratios (3.33 and 6.87)and probably come close to 12lbs with a powerpipe but you probably should have a 3.12 available just in case. Sci vortech right?

Dwain explained the 8 inch pulley deal perfectly.

10 rib is doable but it's over kill big time and TIGHT. Search youtube for channel BREW2L he had a good video showing a ti with renegade brackets using 10 rib. Imo 10 rib isn't worth it for anything stock block. More money, more clearance problems, pita to change the belt.

 

[96pushrod]

I’d just stick with 8 rib. You can reliably make 600whp+ with a 8 rib setup.

 

[Fast4Eye]

Alright so sounds like you basically have the same setup. I have a Sci it with heritage gears also, anderson power bypass and yes a tubular GT40 which is basically a cobra. If I'm going to see 13#s or close to it, then that's enough for me.

Not looking to break more parts than I really need to. So I think I'll stick to the 6.87with a 3.33. Is it worth using the overdriven crank 6.87?

 

[ndmp40]

One warning on the Powerbond.
I usually use Romac, but on a mild build I am doing now, I put a Powerbond on it. Well guess what I found today when dressing the engine- the pulley mounting holes are not all drilled to the same depth, and the thread tapping they did was not at the same depth and not all the way to the bottom. This means the bolts I was using bottomed out on three of the four holes, just enough to touch the pulley on two, but the threads didnt go deep enough on one so the bolt hit bottom before it reached the pulley.

I could easily see someone thinking their bolts were tight but what is happening is the bolt is bottoming. This is bad in any situation, but imagine this on a blower motor.

No more Powerbonds for me.....

 

[Fast4Eye]

One warning on the Powerbond.
I usually use Romac, but on a mild build I am doing now, I put a Powerbond on it. Well guess what I found today when dressing the engine- the pulley mounting holes are not all drilled to the same depth, and the thread tapping they did was not at the same depth and not all the way to the bottom. This means the bolts I was using bottomed out on three of the four holes, just enough to touch the pulley on two, but the threads didnt go deep enough on one so the bolt hit bottom before it reached the pulley.

I could easily see someone thinking their bolts were tight but what is happening is the bolt is bottoming. This is bad in any situation, but imagine this on a blower motor.

No more Powerbonds for me.....

I'll make sure to give mine a once over before installing, but I already bought it and it seems to get good reviews, but thank you!

 

[SNK VNM]

Alright so sounds like you basically have the same setup. I have a Sci it with heritage gears also, anderson power bypass and yes a tubular GT40 which is basically a cobra. If I'm going to see 13#s or close to it, then that's enough for me.

Not looking to break more parts than I really need to. So I think I'll stick to the 6.87with a 3.33. Is it worth using the overdriven crank 6.87?

You have a Sci with heritage gears?

Why would you want to overdrive the crank?

 

[Fast4Eye]

You have a Sci with heritage gears?

Why would you want to overdrive the crank?

It was more of a precaution thing if I ever wanted ti run more boost, I could get the smaller pulley but still have enough belt wrap to avoid slipping.

I realized that was kind of pointless and just bought the 6.87 crank with a 3.33 blower pulley

 

[96pushrod]

You have a Sci with heritage gears?

Why would you want to overdrive the crank?

Larger crank pulley also allows smaller head unit pulley, which is beneficial on a ribbed setup.

 

[SNK VNM]

Larger crank pulley also allows smaller head unit pulley, which is beneficial on a ribbed setup.

Right, which would be a 8 inch not a 6.87.

He said

So I think I'll stick to the 6.87with a 3.33. Is it worth using the overdriven crank 6.87?

Maybe I'm missing something but a 6.87 is offered in 2 different crank pulley diameters, 6" and 4.75".

 

[Fast4Eye]

Maybe I'm missing something but a 6.87 is offered in 2 different crank pulley diameters, 6" and 4.75".

Yes, the 6.87 8rib kit is offered in the non-underdrive and underdrive on their website. I bought the underdrive version as I have over drive water and alteenator pulleys.

 

[Fast4Eye]

Larger crank pulley also allows smaller head unit pulley, which is beneficial on a ribbed setup.

Would a larger crank pulley not allow a larger head unit pulley since it would be spun the same speed while maintaining beltwrap?

 

[96pushrod]

Would a larger crank pulley not allow a larger head unit pulley since it would be spun the same speed while maintaining beltwrap?

Yeah that’s the benefit of the larger crank pulley. You can do a smaller head unit one and gain more belt wrap.

 

[Fast4Eye]

Yeah that’s the benefit of the larger crank pulley. You can do a smaller head unit one and gain more belt wrap.

Wouldn't you get more wrap only on the crank? The head unit would still spin if there's less surface area and its being spun faster now