[mitmaks]

I've heard NASCAR uses 355 engine that runs around 10K rpm's I've wondered how do you make small block rev so high, special crank? rods, etc.

[DoubleVision]

my instructor in college always built drag cars that revved to 9 grand, and I asked him how he did it, and he said "valvetrain" and that was it. but yes to rev that high, it must have a high dollar likely billet crank, oliver connecting rods, and a valvetrain that will support it all and many other things I won`t mention here, you can find out much info on the net on there engines.

[BOBCRMAN@aol.com]

If you check it out you will find that they get the 355 cubes in a different configuration than a factory chevy, try a 4.120 bore and a short stroke and you get quite a revver!

[eight90]

Sorry guys but Nascar uses 358 Cid engines not 355 cid. 4.030 bore with special 3.50 stroke.

[2wld4u]

......

[trees]

Saaay what??? You mean the good ole boys are not using Ford, Chevy and Dodge motors?!? I have seen a few of their motors and there is a lot of exterior plumbing that helps keep the rev masters cooled down. They look more like something from the junkyard wars on the outside. By the way, lets get a pool going to see who is correct --- BobCMan or eight 90. If you want, I'll visit one of the local shops and get the straight skinny.

Trees

[gone2fast]

heres what we use in a super stock on the dirt track, and it turns 9000+ with no problem and only changing bearings as you normally would on a race engine (midseason and at the start of each season).

350c .60 over
302 chevy crank....short stroke
400 rods, short skirt silvalite pistons, shaved and they still pop up
port and polished re-valved roller vortek heads,on 2 head gaskets
airgap manifold, demon carb, tricked out proform HEI
lunati roller cam with around 600 lift,
alum flywheel, alum driveshaft, very light rear wheels and hoosier racing tires.


so basicly a very well flowing engine combo with a short stroke. and as light of rotating mass as possible, this works fine for racing but no way would our motor work on the street...the lope on idle is real bad at even 1200 rpm and there is no engine vaccum to speak of.

[FoxThunder 5.0]

dont u ever have problems with valve float? how about the lifters?

[Ohio-Dan]

Trees, You will find that the bore and stroke differ from track to track. Short tracks or a road course with slow sharp turns get the high torque long stroke motors. The super speedway motors are the short stroke screemers. You will also find that strokes will vary a bit as the motor gets rebuilt. Go from a .030" overbore to a .040", and the stroke will become .020" shorter. Any of the engine size limited classes do the same thing. As far back as the Trans-Am series where Chevy and Ford both used a 4X3 302...... Or did they? I know for a fact that the Chevy guys used a 307 based motor on the road course......More torque to come off the turn...Dan

[Super Streeter]

Most cup motors are 4.125" bore with 3.25" stroke and anywhere from a 5.800 to 6.0" long rod.They use the short deck bowtie smallblock {formerly know as the lowdeck rocket block}with 2 relief flat top pistons,SB2 heads and a flat tappet camshaft with about .700" lift after the Jesel rockers get done with it.Believe it or not,I think the flat tappets were put into place since the heavy pushrod type valvetrain would have beaten a set of roller lifters to death in 500 miles.Typically they develop about 720 hp at around 7800rpm out of 358 inches with a single 4150 type carb.An engine might see 8000+ rpm when downshifting into a turn,but they dont really see full power at over 8000 rpm.

[dirtlmfan]

It's amazing how much $ goes into one of these cup engines. Probably more than any other form of racing. Because Nascar WC has such a big fan base, sponsors are willing to spend astronomical amounts of money to be competitive. If you count R&D costs, it's hard to believe how much money they spend on these engines. That's why they can turn those RPM numbers at those horsepower levels.

[TurboS10]

Originally posted by eight90
Sorry guys but Nascar uses 358 Cid engines not 355 cid. 4.030 bore with special 3.50 stroke.

No eight90, you are quiet wrong! Bob and Super Streeter are on the money. There are a few variations, but most are in the 4.12 bore 3.3 stroke range with some real long rods (6.2) and small journal cranks. All are SB2 heads as far as I have seen.


Gone2fast, how you gonna get those 350 pistons to the top with a short stroke and short rods? You are confused....


Chris

[gone2fast]

trust me i am not confused....you didnt read it right.
short stroke crank, long rods, SHORT skirted pistons.

This has the pistons -25 thousanths out of the deck thus the 2 head gaskets and a little fly cutting on the pistons.

This was a season old when it was destroked, and I can't remember how much the block was decked when first built


as for float we have not seen it, then again we used the best parts we could.mostly luanti......except we had to make valve covers , seems not too much call for tall covers and open breatheing on normal vortec center bolt heads.

[engineczar]

Originally posted by eight90
Sorry guys but Nascar uses 358 Cid engines not 355 cid. 4.030 bore with special 3.50 stroke.

Even sorrier but the current trend for the cup cars is a 4.125 bore and a 3.335 stroke.

[troy-curt]

When I build a performance engine for street or strip, If it wont go 9000 grand on first test, I redo it till it will. It`s no big deal to build a 9000 grand Chevy engine. just my 1/2 cents worth.

Troy,