Bret,

Are you saying you have some LT1's turning 7500 rpm with hydraulics? If so, how much power are they making at 7500 and do any of those guys post here on the board?

Curious because I haven't seen anyone showing dyno runs to 7500 rpm (not with hydraulics) since I've been here.

I still think guys get too hung up on flow numbers. If you think that 300 cfm is 300 cfm whether it come from a high-port race head or a low port 23º then you're too hung up on flow numbers. These heads will look like two different animals when you start pushing them at depressions beyond 28" H2O.

-Mindgame

 

MG,
Look up Anderson Ford Motorsports and he has done much research and testing on hyd lifters at 7500+RPM's and offers his lifters fo sale.

300CFM is 300CFM if it comes out of the toilet.

 

Checked out the website... he offers camshafts and springs for sale.... not lifters. Anderson states that the factory lifters are used.

My question isn't, "Are guys doing it with hydraulics?"... rather... those claiming to do this... what are your results?

We use to run flat tap hydraulics to 7500 rpm all the time. You modify the lifter so that it is basically a "solid" with very little plunger movement. I already know it can be done but IMO, without very low valvetrain mass it's a PITA.

When you consider that a solid can rev to 7500 rpm very reliably and still be low maintenance at that level, it just doesn't seem worth it IMO. But then, I don't want to question motives. Guys might start questioning the sanity of anyone who wants to build a 450+ ci small block or perhaps convert a set of race heads for the LT block.

Different strokes I guess huh.

And to that I have to ask... why does head development tend to go in the direction of a raised port (more direct line of sight) if this isn't an issue?

I am under the impression from one very savy head development guy that it takes much more depression than 28" H2O to see flow detachment on a good 23º cylinder head.

.5 mach @100ºF is ~580 feet/sec, which is better than 75" H2O.

I wonder how the straighter port flowing the same cfm at 28" H2O will fair at these speeds in terms of seperation.

-Mindgame

 

Mindgame,

I'll help ya out on the hyd going 7500rpm if you help me out with how you calculate this stuff....

Larry Meaux did a conversion on another board on plate motors with 11" of vacuum at WOT, that's 149.6" of H2O.

On the 7500rpm stuff, it was actually by accident that it happened. A customer wanted me to look at his dyno chart to make sure there wasn't valve float. It was a system designed for 7000rpm max, not 7500rpm but he ran it up there and it had zero signs of float, but had other problems. The right lobes and low mass items helped do it, but not to the extent you would think.

Bret

 

MG,
So I understand,a port has to be dead streight and high enough to not let the cyl wall interfere with the air until it gets to the piston that's coming up and have a LARGE bore to let the turbulance settle down. In other words if ya didn't have valves ya could see the piston through the intake end of the port when the piston is down.
I don't know of any heads like that and probably couldn't afford them if I knew where to get a set.
Might call WJ and have him make a set from a solid chunk of billett. Mucho$$$$$$$$

 

Fellas let's please keep this on topic.. Seriously.. Lot's of good info get's wasted when a post ends up like this one might..

I'm converting a set of "race" heads for a LT motor.. For the simple fact of seeing what it can do.... Go big Go home if your pocket can keep up... Hobby's not cheap, and enlisting the right group of people to help you get your combo together is the key.. opinion's are like Azzhole's everyone's got one.. Listen to those in the know, use the search, Jim Lab did a 215rr and it made great power, i'm sure if you do a search for member jimlab you'll find stuff about his setup which is bascially what your looking to do.. IMO w/ the cost of converting a set of Gen 1 head's over to rev. cooling being 300-500 bux ,it might pay too look into some of the brodix, dart stuff as they're affordable and have been proven to make excellent power...

 

http://cgi.ebay.com/ebaymotors/AFR-2...spagenameZWDVW

I wish I didnt already buy my heads

 

That's a kickass deal!!!..

 

I know, I have been watching closely, and I am thinkin seriously about biting!

 

Yes please do! Those are my heads actually. Bid away, i need the money for a downpayment on a house!!!

 

a house? damn, that sucks.... trade fast car for a house.

 

hey dan,,,wheres my check for the tires? youre not planning to rip me...are u?

 

No . Sent you a PM on it. Got better things to do on this forum than trying to cheat someone out of $130. Anyway a PM has been sent your way.

 

Did you try and sell that package a couple of months ago? I saw that same package if not very similar a while back.

 

yes it was on a couple of months ago I remember salivating over it.
-b