[Razor427]

Is the LT1 pump with a 8mm lash cap equal to a LT4 pump?


Ray

[boostednut]

Short answer until someone else who know's the specifics is no. The peak pressure I believe in ecu is higher on the lt4 pump, and some kind of pump internal difference. But I think you're asking in terms of functional flow...

I'm unsure about what lash cap you can run in what situation, because I do understand that if you run the wrong lash cap, and the pump doesn't mount correctly you'll break the pump off. So... running a cap on stock cam is something I don't fully understand.

Hopefully someone can clear up the details/provide more info on a stock lt1 pump and stock cam can (with a lash cap). It seems to be the least discussed, probably because most places won't make any money off selling a lash cap.

[62nalide]

that's a big NO

[Razor427]

Check this out.....

https://www.corvetteforum.com/forums...learances.html

[parish8]

Originally Posted by Razor427

Check this out.....

https://www.corvetteforum.com/forums...learances.html

There is some solid info in that link but it implies a lash cap on just a lt1 pump with stock cam will add fuel. I don’t see how this would be possible.

Read that entire link to get an idea of how things work. Then read this: a stock lt1 pump has preload on it from the factory. Installing a lash cap will only move the piston up higher in the stroke. It will not increase the stroke.

[JFM-jr]

Originally Posted by parish8

There is some solid info in that link but it implies a lash cap on just a lt1 pump with stock cam will add fuel. I don’t see how this would be possible.

Read that entire link to get an idea of how things work. Then read this: a stock lt1 pump has preload on it from the factory. Installing a lash cap will only move the piston up higher in the stroke. It will not increase the stroke.

I agree and I started a thread over there a few weeks ago asking about how the cap increases pump output with no additional stroke. I was told its where the cap moves the strokes operating range. It relocates the operating range to a more optimal zone. I of course asked if anybody has solid data to back this up and there is none. So its still speculation in my book.

Heres the short thread I started

https://www.corvetteforum.com/forums...-lash-cap.html

[parish8]

Without data of some kind there is no reason to believe that. I can tell you for sure a stock cam and lt1 pump has some preload from the factory and that pump is going to see the entire stroke from the cam lobe. I tested it myself.

[boostednut]

Originally Posted by parish8

There is some solid info in that link but it implies a lash cap on just a lt1 pump with stock cam will add fuel. I don’t see how this would be possible.

Read that entire link to get an idea of how things work. Then read this: a stock lt1 pump has preload on it from the factory. Installing a lash cap will only move the piston up higher in the stroke. It will not increase the stroke.

Yes in theory putting a cap on it won't change the stroke distance. Just the start and end heights. So that's what I don't get.

I'm imagining that you use a smaller lash cap, so that you can increase the preload distance. Depending on how the pump is designed this could potentially increase fuel volume per stroke.

But I've yet to see anyone actually explain this. Everyone talks about lobe and lash. But nobody explains this pump specifically in relation to stroke distances. It's curious.

[JFM-jr]

Originally Posted by boostednut

Yes in theory putting a cap on it won't change the stroke distance. Just the start and end heights. So that's what I don't get.

.

From what I was told and the way I understand it it's exactly as you describe. It moves the starting and ending points of the stroke in closer towards the body of the pump. The theory is this area of stroke moves more fuel than the stock area of stroke without the cap. Again unproven without supporting data.

[boostednut]

Originally Posted by JFM-jr

From what I was told and the way I understand it it's exactly as you describe. It moves the starting and ending points of the stroke in closer towards the body of the pump. The theory is this area of stroke moves more fuel than the stock area of stroke without the cap. Again unproven without supporting data.

It's potentially true. But it's just as possible to not do anything to help flow.

Would be nice to see this answered one way or the other. It's pretty simple and should be repeatable.

[parish8]

My money is on no change in flow.

[JFM-jr]

Originally Posted by parish8

My money is on no change in flow.

and im not taking that bet

[boostednut]

Either way there's no excuse to not have any real world info or data on it. Like all it takes is one person to have actually done it to mean anything

[parish8]

Originally Posted by boostednut

Either way there's no excuse to not have any real world info or data on it. Like all it takes is one person to have actually done it to mean anything

What are you waiting for?