Skid Mark - how fast for 5k?

[Bob Holmes]

There's a bit of controversy about quench and turbo's. Personally, I'd like to see it closer than 50-55. I'd be happy at 45.

There is some thought that tight quench may not be beneficial, however, that tends to be applied to max effort applications.

If the 50-55 saves you machine shop costs, then you might want to leave it alone. This is a driver, not a racecar.

[SuperBuickGuy]

The rain is keeping me from taking the block to the machine shop to get decked this week! lol.. I was reading some other stuff that says turbo cars don't care much about quench? I'm looking into that, as I may not want to deck it if that's the case. It's square enough now, I'd only cut it to get the compression. Really, as low as it is already, it's not like it will require the quench to be perfect. It'd be about .055 as is, which I am led to believe is the hairy edge of being beneficial.

Have you guys heard this turbo / quench thing before? It's new to me. I've got a fairly big turbo (for a truck motor..haha) for part two of this fiasco... might as well save the money if it's not gonna care!

The hardest part about building a turbo motor - deciding where to draw the line. Seriously, come up with a power number you want, and build the motor to that hp number. I'm sure quench makes a difference at a certain dollar level.... errr hp level (same thing in my book)... but on a 5k build, I'm not certain there will be any benefit of quench.

Here's where the issue came up with the Buick motor. When you girdle the block, you can go to roughly 1100 hp on a stock block. However, at that level, all the other parts inside are the same as what you'd use for a 2200 hp motor... simply another 2500 (tomahawk block is 5k, but it's a savings of $2500 for machine work that won't need to be done) and a new tomahawk block and you're all set.... consider those words for a moment - simply another $2500...

The first motor, 700 hp with turbos that would support 2200 hp. When I build the 2200 hp motor, all the stuff I bolt to the outside will be the same, but I don't have a billet crank, custom pistons, custom rods, custom cam, custom lifters... you get the idea.


To be clear - my opinion is forget about quench and simply build the car. When you build a full tube chassis car, worry about quench.

[BBR]

So.... ya done yet?

[STINEY]

Instead of crickets chirping, I just hear "meeeeooooow!"

[Beagle]

I might have run into a snag. I was getting a table cleaned off to lay out the engine parts for assembly, and the oh so beautiful Ross pistons have what looks like might be a SCJ valve relief. They're way off the side of the piston, literally off the side of it. Does anyone know if it's a problem to run this with a standard head? I guess I should clay it up and find out.

Off to read the 460 boards.

[Beagle]

1000.00 oooooops. I have a couple of options...

old FMS crank, 521" stroker
4.300 throw with 2.500 journals , found one for 375.00
JE forged 39 cc pistons , 1.545 compression height 1.04 pin 800.00
These would work with the h-beam rods I already have but to get any kind of compression, I'd have to do the D0ve heads up. 9.7:1 with the 72cc chambered heads. The D3's would make a good turbo head on this, low 8's:1

that seems to make the most sense. I am mildly upset about the amount of hours (LOT) spent snorting iron dust if I go this direction.

or -

1700.00 SCJ heads, port the crap out of the manifold, cut and re-weld headers for SCJ flanges.

F is for frustrated. O is for Obtuse. R is for Redundant. D is for Dumbass.

[TheSilverBuick]

Yup.

[Beagle]

I just did some reading, and it's not as bad as I thought. From the compression height I chose (1.545) I have a choice of JE pistons... if I let it go down to 1.525 I can get forged Probes and they are a lot less expesnsive, like 520.00 v. 800-850 and they are cut for both SCJ and production valve reliefs. The guys on 460ford.com indicate you can cut the deck up to .100 (?!) and still have plenty of strength so that opens it up to a lot more choices.

that'd make the extra 55 cubes 895.00, I guess it's not the end of the world, just the end of my budget. Lol. Daaaahmmmmit.

[Bob Holmes]

The important part of a turbo piston is the thickness of the crown and how far the compression ring is from the top of the piston. Don't buy an NA piston for a turbo application, unless you only plan to blow on it softly. (Very few people have the discipline to blow on it softly once they've sucked on the turbo crack pipe)

I prefer to keep the pin out of the oil ring, but sometimes you gotta do what you gotta do.

However, I've been known to throw whatever I've got in the used piston bucket into a street build. The Red Furd has a bunch of used parts, and I'll blow about 18psi max on it. Tune up is critical.

There was a very interesting and surprising post on Speedtalk. Darin Morgan (Pro Mod, Pro Stock all around head porting god) stated that they left the piston as low as .250 in the hole in order to get to the CR that they wanted. I'm a little stunned.

[Beagle]

I think I read that post Bob. Seems to be a lot of argument, I'm not gonna get real hung up on it. When (if) the turbo ever gets put on it, 7 pounds will start showing other weak spots like breaking the rest of the car I think.

The ring package on this is probably about the same as a 350 chevy. The compression height is about the same, although the pin is a bit bigger. The oil ring shouldn't be anywhere near the pin.

I'm mildly okay with the 521" deal. Compression comes in at a little over 9.3:1 which I think will be okay with iron heads and premium. A couple of points higher (like 11.31:1) with 72cc heads that I may or may not do later. The rest of the parts I already have will work good with the low compression iron head deal.

How much is mallory metal? From what I read the bigger pins on the FMS crank (2.5 v. 2.2 chevy size) might need heavy metal to balance.

[milner351]

Mallory metal is stupid expensive - call the crank shop before you proceed. I was able to do a cheap balance job using average weight of the piston/rod set of 8 and only having to drill the crank counterweights, no added metal required.

[Beagle]

http://www.ebay.com/itm/FORD-RACING-...2a73d1&vxp=mtr

1200.00 for a forged piston h-beam 521" kit. I thought about just getting the pistons and crank from it, but the pins on these pistons are .990 and my rods are 1.040. I need to give Probe a call and see what they would charge to do a set with the bigger pin I guess. I kind of like the pistons having both notches cut already.

On the other hand, the dirtball part of me is saying "just cut new reliefs in the ones you have"

[milner351]

Do you have a good local machine shop? Worth a call to them to look over your options - they may come up with additional options you didn't know you had.

[BBR]

Mark Oneal is on the bullet and 460ford. Should be fairly easy to get ahold of. He might even have a similar deal.

[Beagle]

good point James, it's worth asking. As Belushi once said "It don't cost nuthin"