Dirt Circle Track Engine Build Advice

General engine tech -- Drag Racing to Circle Track

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W2Racing09
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Dirt Circle Track Engine Build Advice

Post by W2Racing09 » Tue Aug 08, 2017 2:28 pm

Hello all,

Looking for advice on an engine build. I've got experience with repairs for passenger car engines as a mechanic, and have a good understanding of race engines. This off season I am looking to build my own 358 Sprint Car engine to run at my local track. Right now I'm just looking to kind of get a ballpark idea of the price so this is the best place to start since there are so many knowledgeable posters. Here are the track rules:

77. Cast iron production blocks are mandatory. GM steel heads must have 23 degree valve angle.

78. 358 cubic inch maximum displacement.

79. Flat top pistons only, no domes or dishes and top of piston square to the bore of the cylinder. Zero
deck height.

80. Maximum compression ratio of 10.75:1 as checked by whistler gauge.

81. Maximum 3.5 inch stroke. Weight of crankshaft not to be less than 46 pounds.

82. Cast iron heads of stock configuration mandatory. Stock valve guide angle, no relocating valve
guides, example GM-23 degrees. No raised intake runners or spread port exhaust. Porting into runner 3/4 inch to match manifolds allowed. port and polish OPTIONAL.

83. Intake port may be matched to the intake manifold or gasket, not to exceed a depth of 3/4 inches.
Intake valve may not exceed .060 inch over stock valve size, i.e.: 2.020" stock - 2.080" maximum.
Intake seats may be cut back under the valve seat with a maximum angle of 75 degrees. No grinding
or acid etching under the valve seat will be permitted

84. Exhaust port may be matched to gasket or header, not to exceed a depth of 3/4 inch. Exhaust
valve size may not exceed .025 inch over stock size, i.e.: 1.600 stock - 1.625 inch maximum. Exhaust
seats may be back cut under valve seat with a maximum angle of 75 degrees. No grinding or acid
etching under the valve seat will be permitted.

85. Grinding in the combustion chamber will be permitted. Welding in the combustion chamber will
be permitted for repair purposes only. No welding to reshape the combustion chamber. The combustion
chamber will be defined as beginning with the head gasket area and ending at the top of the valve seat.
This is to allow the participant to meet the 10.75 to 1 compression limit and allow competitor valve
jobs to be performed to meet specifications outlined in intake and exhaust specifications.

86. No modification allowed to heads that would allow the use of down nozzles or multiple spark plugs
per cylinder.

87. Must be naturally aspirated. Fuel injection or carburation allowed. Timed and/or electronic fuel
injection units are prohibited,

88. No V-6 engines.

89. No titanium, plastic or carbon fiber components for crank or rods.

90. Total weight of car and driver may not be less than 1500 pounds at any time. Weight to be measured as car comes off of the track in the condition that it took the checkered flag. No bolt on weight. Weight measured by speedway scale in the center of the pit area.

91. No traction devices are allowed. in question

Budget is a concern, I'm not expecting to pay peanuts for this but I also can't afford to have the biggest baddest 358 in existence (sadly). I'm looking for a combination of affordability and power/speed.

Thanks to all for checking out my post and let me know if I left anything out.

Tuner
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Re: Dirt Circle Track Engine Build Advice

Post by Tuner » Tue Aug 08, 2017 5:51 pm

Chevrolet Performance Vortec Assembled Large Port Cast Iron Cylinder Head, 225cc Intake Ports
Large Port Cast Iron Vortec Cylinder Head
225cc Intake Ports
77cc Exhaust Ports
65cc Combustion Chambers
2.000" Intake Valve
1.550" Exhaust Valve
Assembled, Each
Chevrolet Performance 19331472

http://www.jegs.com/i/Chevrolet-Perform ... 2/10002/-1

Chevrolet Vortec Cylinder Heads' fast burn combustion chamber and high-velocity ports combine to produce big horsepower. Vortec Heads can be mildly ported for additional performance and milled up to .040'' for increased compression ratio. The Vortec Heads come with various intake and exhaust valve sizes to complement the high-velocity port design and your performance needs. Vortec Heads outflow Bow Tie Heads right out of the box and are a 20 to 40 horsepower bolt-on increase over earlier cast iron small block heads. Vortec Heads require a Vortec-style intake manifold due to an improved manifold mounting flange and gasket design and raised intake ports. Modifying the heads to accept early intake manifolds is not recommended. Vortec Cylinder Heads fit all 1955-Present small blocks except LT1/LT4 reverse coolant flow engines and current LS1-style engines.

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Re: Dirt Circle Track Engine Build Advice

Post by cstraub » Tue Aug 08, 2017 6:07 pm

In this type of racing you can have 1 guy spend $6K on a complete short block then another guy may spend that on just crank , rods, and pistons. Huge sliding scale on what is spent on these types of engines and attention to detail is what wins races. You can start at $8K and go up from there. Not out of the realm for a late model stock to run $25K.
Chris Straub
Performance Mfg.
http://www.straubtechnologies.com
www.distributorgears.com

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Re: Dirt Circle Track Engine Build Advice

Post by pamotorman » Tue Aug 08, 2017 6:29 pm

it is not expensive to race but it is expensive to win

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Re: Dirt Circle Track Engine Build Advice

Post by Newold1 » Tue Aug 08, 2017 6:36 pm

Pamotorman - EXACTLY++ These builds are strictly a matter of two questions HOW MUCH DO YOU WANT TO SPEND TO RACE! or HOW MUCH DO YOU WANT TO SPEND TO WIN! Make that decision now and then decide which answer you can live with and afford!

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Re: Dirt Circle Track Engine Build Advice

Post by billet » Tue Aug 08, 2017 11:52 pm

W2Racing09 wrote:.

90. Total weight of car and driver may not be less than 1500 pounds at any time. Weight to be measured as car comes off of the track in the condition that it took the checkered flag. No bolt on weight. Weight measured by speedway scale in the center of the pit area.

WHAT????? I'd spend money to get down to 1500# and not worry about how much power I had. :shock:


EDIT: I missed the sprint car part, my bad was thinking modified or some sort of stock car

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Re: Dirt Circle Track Engine Build Advice

Post by RCJ » Wed Aug 09, 2017 6:17 am

I would use a callies compstar crank and rods,Srp professional series pistons. Never used the gm vortec heads myself ,but that is what I would try on this build.How you do the valve train would make a big deal on price.I would agree that $6000 would be the low end price.

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Re: Dirt Circle Track Engine Build Advice

Post by pamotorman » Wed Aug 09, 2017 7:51 am

of it is a winged sprint car the more power the better but if non winged sprint car hooking up to the track will be the problem

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Re: Dirt Circle Track Engine Build Advice

Post by W2Racing09 » Wed Aug 09, 2017 2:34 pm

pamotorman wrote:of it is a winged sprint car the more power the better but if non winged sprint car hooking up to the track will be the problem
Hey all, thanks for the replies.

This would be for a winged sprint car (358 Sprints at Trail Way Speedway which is a little 1/3 mile track). I don't plan to run anywhere else for the time being (I am about 8-10 minutes from the track). The wings are not quite as big as the 5x5 wings that the 410s run. A 358 wing is maximum 16sf so a little less down force than a normal 410. $6000-$8000 is what I was hoping to spend if possible. There are guys out there running $25k engines, and I've seen some for sale used for $3500 in the past I'm looking for something in between those two options in terms of cost.

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Re: Dirt Circle Track Engine Build Advice

Post by levisnteeshirt » Thu Aug 10, 2017 8:16 pm

Any cam / valve spring restriction ?

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Re: Dirt Circle Track Engine Build Advice

Post by Krooser » Thu Aug 10, 2017 10:53 pm

Buy a good used engine from a front running team.... freshen it if needed. I see used $40k super late model engines go for $10k everyday on-line. 800 hp isn't going to do much for you if you don't have the knowledge on chassis setup and a skilled driver.
Last place in the B-main is better than anyplace in the grandstands...

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Re: Dirt Circle Track Engine Build Advice

Post by levisnteeshirt » Thu Aug 10, 2017 11:56 pm

Got any friends running the class ?

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Re: Dirt Circle Track Engine Build Advice

Post by englertracing » Fri Aug 11, 2017 2:42 am

400 Cleveland block with a 302 crank :P
4v Cleveland head.


Or I guess like the other guys said.
But go big bore short stroke.
And use an IR cam.

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Re: Dirt Circle Track Engine Build Advice

Post by Meehan Race Engines » Tue Aug 15, 2017 7:55 am

I'm guessing by those rules you can run a roller cam , dry sump and use a MSD Pro Mag?
Gary Meehan
Meehan Race Engines

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