turbo

iTrader: (10)

What makes em rev to 9000rpm? Anyone know the specs on the motors?

I also know they rebuild them after each race too. <img src="gr_eek2.gif" border="0"> I know you wouldnt be able to turn them all the time like that without it.

Just curious.

Casey

Crazyquik

Well the Chevrolet for example is based on the SB2 small block, designed pretty much just for racing. Of course they use lots of lightweight parts, have a good bore to stroke ratio (which differs between tracks dependant on the needs of that track), big head ports, big solid lifter cams, dry sump oil systems help a lot, etc. They'll rev higher than 9k too. I've seen some during a race go to maybe 9500, and thats an engine thats lasting 500 miles. A qualifying motor would be spun even tighter.

McRat

I'd like to know also.

My guesses would be:

Thin rings on light pistons. Stops ring "flutter" and burned pistons. When piston speeds start to exceed 4000ft/min(?) conventional rings stop working, and they shatter or seize.

Huge cams, ports, and manifolds. Washed down with "star-wars" valvetrains.

Strong bottom ends.

Dry sumps.

If you could spin a stock LS1 engine to 9000, you could get ~450rwhp (300+50% of 300) with no other changes; same volumetric efficiency. You'd never make it with off the shelf parts I don't think.

Crazyquik

They probably use gas ported pistons.

racer7088

NASCAR engines have very good heads and not many cubes so they spin very high. They have the money to run the valvetrain to take it there as well. The main limit on them is the intake restriction and rpm as compared to making them last the whole race.

Crazyquik

When you say intake restiction, do you mean the size of carb they run? They only run restrictor plates at 3 tracks dont they?

racer7088

Yes you're right. They still don't get to run Dominators! They have a single 4150 carb and sometimes have to run restictors too. With the restrictors they won't turn quite as high or at least make power as high!

DCPunkSteve

Most of the damage done to an engine that has been over rev'd comes from poor valve trane control. Jesel, for example, makes a setup for regular SBC's that practicly gives you the capabilitys to turn 8000rpm on a street engine. Another example is the LT5 engine. The thing is rev limited to protect the accesorys, and not the engine. I've seen these engines dropped into race only Vette's and they turn close to 9000rpm. Even the Caddy Northstar has a pretty high RPM, and all thanks to good valve componants. I would think any well built engine, using a quality and well balenced rotating assembly would be able to run to 9000rpm an survive just fine, as long as you have the valve trane to back it up.

Crazyquik

I am thinking the rev range of a WC car with the restrictor plate is under 7k. I know it cuts hp to under 450ish (supposedly). Ever been to a NASCAR auction? You see some really trick stuff there sold for cheap, of course it helps to live within 100 miles of 50 Busch and Winston Cup teams <img src="graemlins/fluffy.gif" border="0" alt="[Fluffy]" />

I'm thinking for a restrictor plate motor they'd actually run a much longer stroke with a smaller bore than normal, to get a better "pull" of intake charge in. Its been common for years to build circle track motors with a longer stroke if you have to run in a 2 barrel only class, so its its quite possible that one reason they run lower revs on the restrictor plate tracks is also due to bore-stroke reasons.

J.

MIGHTYMOUSE

iTrader: (59)

boring/ stroking really doesnt do jack for them with the restrictor plates because they still have to stay at the maximum displacement of 355 cubic inches, though the above is correct.. they would want the best compromise of longest stroke possible. its just a combination of very strong, and very well balanced parts.

[ December 15, 2001: Message edited by: MIGHTYMOUSE ]</p>

Bill00Formula

iTrader: (4)

A few months ago one of the commentators was talking about that and he mentioned was oil is sprayed on the rocker arm assembly.

Joe Prince

I used to work for NASCAR Winston Cup series on the Jasper #77 car for 2 years and I am leaving for Team Sabco Busch series in Feb, this is what I have seen and heard. Very strong yet light weight rotating components, short piston skirts, lightweight to the point that I have seen cars come into the pits with a bad vibration and when the driver is debriefed as to what happened, come to find out that the chassis bottomed out and bent the crankshaft and or tossed the ballancer! talk about being hollowed out, anyway, I have seen the 720-730 horsepower SB2 heads, but they are flowed at different ranges than we are used to seeing. at 28" they flow roughly 335 cfm @ 692-720 lift and they use some strange looking solid roller cams lobes that are large rollerbearing journaled, when the cam is placed in the motor, you can just spin it with your hand and it will go on for about 30 seconds. Valve train components don't look too much different than what we use besides having beefy tripple springs Ti valve train parts light weight solid lifters, rifel drilled cams and what not. One thing I know for a fact where they pick up good RPM and power believe it or not is in internal oil management, I have heard some talk about dry sump oil pans/windage set-up's being worth up to 35 FWH. When we would start these motors to check oil pressure/hot temp to roll them out of the shop into the transporter they sounded like a bucket of bolts, they are very noisy untill they hit 170 degrees and clatter real badly. They use of low surface friction V belts and UD pullys are standard. Carb tuning is really important to, in testing, they run 8 WB 02's on every header primary and the data is logged to an onboard computer to see how the 4 corner jetting needs to be adjusted especially going around high G force turns, one bank goes leaner than the other, they run there motors even leaner than we do to the point that white ashy soot is collected in the tailpipes from after running WOT. I might remember some more stuff.

peter d

[QUOTE]Originally posted by turbo:
[QB]What makes em rev to 9000rpm? Anyone know the specs on the motors?


350 destroked to reduce piston speed.
WC motors--358 cubes max..use the siamese bow-tie block.. strokes will vary from 3.300" plus and bore combos 4.125" plus to meet the 358 cubes.

racer7088

Joe Prince,

Did you really see many triple springs being used? Most shops run the engines only aster warming the coolant and oil beforehand but some do run big cylinder to wall clearance!

66ImpalaLT1

Do they really run 8 WB O2's or do they use 8 exhaust gas temperature probes?

Eric

Matt98SS

[quote]Originally posted by racer7088:
<strong>Joe Prince,

Did you really see many triple springs being used? Most shops run the engines only aster warming the coolant and oil beforehand but some do run big cylinder to wall clearance!</strong><hr></blockquote>

yes I like seeing the extension cord plugging into the back of the window area for that oil heater <img src="gr_stretch.gif" border="0">

a guy I know build engines for ARCA ReMax series Nascar.

they all have there own secrets

Wicked Ls1

I know just with a cam and what not our engines are hitting 7K with 6speed Trans. The only problem is the higher you rev the quicker your engine wears down. <img src="gr_sad.gif" border="0"> We can make it rev pretty high, but it's not suited for a daily driver for obvious reasons.