Turbo Carb Spring Question

[treewhacker]

I was talking to a guy last weekend about the slide springs in the CV Carbs, he said he changed to the red springs because at higher altitude the slides wouldn't open. Do these springs need to be changed when you have a turbo too? He claimed a huge performance gain going to the red ones.

 

[Buckeye]

I asked this ? to Supertuner:

Do you think there would be any benefit to using these springs with a turbo?

I think it depends on what you are looking for in the way of improvements and what style operation the engine will see. With th increased forced air induction that a turbo charger provides, you really increase manifold pressure. Manifold pressure is higher at idle than at WOT, therefore the increased forced air might be opening the slides almost immediately anyway. Testing in the field will tell you if you have a real good timing system. About the only type of dyno that is capable of measuring this and collect accurate data in an inertia ENGINE dyno like mine. If this testing is of any interest to you, I would be happy to provide you some dyno time. You will remove every bit of guesswork.

Freddie

 

[treewhacker]

That's what I'm getting at, the slides open with vacume, not pressure. Also, there is no boost when you're idling to speak of, so wouldn't we still need lighter springs at higher altitudes to overcome the higher atmospheric pressure there. The stock springs are for 0-4,000'

 

[thebest]

when you got turbo your with pressure and not vaccum anymore in your carb and bowl . vaccum is only for not turbo engine.

 

[wildbill]

I talked with Barry at Holtzman and he told me the stock spring is really set up for a turbo. He said they are really designed to be at -5000ft below seal level and that's what a turbo does. However if the vacuum is what is working on the springs, maybe this isn't true??? I'm just passing on info from Holtzman.

 

[spray25]

The slides are no longer under vacuum. They are under positive pressure from the turbo. There is a line from the airbox to the slides now.

The weeker Holtzman springs work well with a stock sled because at altitude there is less vacum pressure.

Michael had cut his springs when his sled was stock. Upon installing the turbo his sled ran like crap until he replaced the springs. He and Barry seem to be in agreement that the stock springs are the best for the Bender setup.

 

[Snow Fever]

I have the original springs with six coils cut off them , needles dropped one with 130 main jets. Works way better on my set up anyway.

 

[treewhacker]

Snowfever
Ray said you have the 8BU00 weights, tell me your exact clutch set up. I have the same weights, but haven't done a lot of testing. Right now I need miore weight in the heel because It's over reving and dropping back after 5 seconds of pull. I have OPO primary spring, silver secondary, stock helix and wrapped at 70.