[RAIV-Z]

Making some progress on the heads!

[TOP 452]

Looking good ED. Waiting to here some thunder

[Tom Vaught]

VERY IMPRESSIVE

Looking forward to watching a dyno test at some point.

Tom Vaught

[bankbook]

Thats going to be a great combo!

[shaker455]

Very good Mr.Ed!

A great build takes time.

[Jim Robertson]

Very Cool! Best of luck with it.

[jdw_poncho]

Are you planning on leaving the deck wet or plug the holes? Have you looked at the possiblity of adding the extra bolt holes in that head? Just curious if the layout allows it?

What size turbo's?

[NHRASuperStock455SD]

We did the newly designed header flanges yesterday and put them on the heads. Now we can do the exhaust. These heads have the alternate valve spacing for the 4.350 bore. This head will have 2.30 intake valve.

This will be our standard CNC program for the stock head castings.

[john marcella]

I would like to get a hold of this head. I kinda got an idea

[RAIV-Z]

Originally Posted by john marcella

I would like to get a hold of this head. I kinda got an idea

I'm all ears!

btw... Your mailbox is full.

[RAIV-Z]

We’re going with Turbonetics 88mm turbos.

[cgeise]

Plan ahead for back pressure issues -

[RAIV-Z]

Anything specific we should watch out for?

[cgeise]

On my 525 - it starts to get into back pressure "issues" at about 22 to 24 psi - we had the tubine housings modified and it helpped but is still there - I have been told the only way to fix it is 91s or 94s -- and those things are huge -

[Tom Vaught]

Originally Posted by cgeise

On my 525 - it starts to get into back pressure "issues" at about 22 to 24 psi - we had the tubine housings modified and it helpped but is still there - I have been told the only way to fix it is 91s or 94s -- and those things are huge -

I would like to hear more about these issues at 24 psi of manifold pressure in the intake. What is the pressure in the Turbines at the same boost levels?

Tom Vaught

[NHRASuperStock455SD]

Originally Posted by Tom Vaught

I would like to hear more about these issues at 24 psi of manifold pressure in the intake. What is the pressure in the Turbines at the same boost levels?

Tom Vaught

OK CG you got the ears of the "big dog" boostman listening. I have the explanation from my engineering student son, but students are silent when the professor is ready to chime.

[twov8sandat4]

Originally Posted by cgeise

On my 525 - it starts to get into back pressure "issues" at about 22 to 24 psi - we had the tubine housings modified and it helpped but is still there - I have been told the only way to fix it is 91s or 94s -- and those things are huge -

Did they go into specifics on why those would fix the problem? Better/bigger turbine housings than the 88s? just curious

[NHRASuperStock455SD]

cg did you dyno this engine? Normally aspirated and then with boost?

[cgeise]

I have never run the car on the dyno with no booste - but I know it will run mid to high 9s with out the turbos working - dont ask how I know - the back pressure starts to creap up into the 2 to 1 range when it goes over 24- to 25 psi - and yes - the bigger turbos seam to have a better - more efficient turbine housing - but the whole turbo is so big it would take a major rework to make them fit -

[taff2]

Couldn't you bypass some of that backpressure through the wastegates? Back in the day,turbo drag racers used to use small turbine housings for quick boost response and then run a lot of the exhaust gases through the 'gates.