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Working on a Circle Track Street Stock Engine Option... Need some opinions!
Circle track guy here... I am currently working with my divisions tech inspector to attempt to find an additional affordable engine package for our Street Stock division.
Right now we have a pretty balanced program with GM602 crate engines using a 650cfm 4150 Holley 4bbl carb, and built/open engines using a 500cfm 4412 Holley 2bbl carb, however the cost to build a competitive "built" engine is $10,000+ and the cost of the 602 crate engines is slowly creeping up as well and are nearing $4000 from GM.
I consider myself decently knowledgeable when it comes to the LS platform, but I have never tried to put together anything like this.
Currently, the engines (crate or built) in the division make generally around 375hp and 395tq at the crank for a competitive piece. The goal I would have for this option would be right around there.
Below is a list I have created to build this rules package, but I wanted to run it by those who may be smarter than me, to potentially get suggestions on how to keep it not only affordable but efficient.
Engine
a. GM LS Based LM7 5.3 Engine. Cast Iron Block ONLY.
b. Only OEM 706 or 862 Cylinder Head castings allowed. Cylinder heads must remain stock as manufactured. No de-burring, porting or polishing. OEM Valves and valve jobs only.
c. Rocker Arms to remain OEM as manufactured. Trunnion upgrade, OK.
d. Rotating assembly must remain stock OEM as manufactured. OEM GM Rods and Crank only allowed. No lightening of any parts allowed. No gapless rings. Replacement pistons okay, must use Keith Black 3519HC-STD or 3519HC-25MM Pistons. 3.790 maximum bore. Piston Ring Set E937K or E937K25MM must be used with replacement pistons.
e. 9.5:1 Compression Ratio Maximum to be checked with the whistler.
f. OEM replacement engine bearings only.
g. Must use OEM or OEM replacement balancer.
h. Spec camshaft to be used Chevrolet Performance #12561721 to be checked with the Cam Doctor. OEM replacement timing set only. No double roller chains.
i. Chevrolet Performance Valve Springs #12499224 must be used. Must use OEM Retainers and Locks.
j. HP Oil Pump Upgrade recommended. Melling #10295
k. Milodon 31527 or Kevko LS1092 oil pans, OK. Must use oil filter relocation kit with aftermarket pan. Oil filter and lines must be mounted inside the chassis and away from exhaust components. 36" maximum line length.
l. No crankshaft oil crapers or aftermarket windage trays.
m. No oil coolers
Exhaust
a. Headers must be Schoenfeld 186LS with 1-3/4" Primary.
b. Maximum exhaust pipe diameter is two and one-half (2 ½) inches. Exhaust pipes must exit six (6) inches behind the driver’s seat and under the car. Both pipes may be located on the same side of the car. No crossover or “H pipes” allowed. Pipes must maintain a minimum of one (1) inch separation.
c. Mufflers are mandatory. The only approved muffler is the Lobak RCM 12” Spiral Flow (part number: RCM251225). Moroso muffler part #94050 may also be used.
d. Only one (1) muffler per exhaust pipe. The end of the muffler must be located six (6) inches from the end of the exhaust system. The last six (6) inches of the exhaust system must be turned down. The exhaust system must extend six (6) inches beyond the driver’s seat and remain under the car.
e. Mufflers must be removable for inspection.
f. Muffler must remain complete with ends as manufactured.
g. Check valve tubes are not allowed in any part of the muffler.
h. No wrapping or coating of any part of the exhaust.
Intake and Ignition
a. Must use Holley 300-130k Kit from www.jegs.comw/ 6200rpm chip.
Carburetor
a. Holley 4150 650cfm as manufactured. No HP parts.
Fuel System
a. Electric External Pump. 14psi maximum, must be regulated.
b. Must have oil pressure activated fuel pump shutoff switch.
c. Oberg valve required no more than 12” from Fuel Cell Feed.
Like I said, this list has been built and spec'd out based on my knowledge and experience with these engines HOWEVER I am not infallible and may be completely off in some areas with my research.
Really appreciate any help or assistance with this project.
THANK YOU!!!
Last edited by slow_poke; 12-19-2018 at 05:52 AM.
Reason: Updated
I really doubt that cam is right since its for AFM/DOD... (4 cylinder gas saver mode).
Exactly my thoughts, not the right part number
Im confused, you say this is a list of parts you have began to compile.... but the list looks like you have no other choice but to run what is on the list?
Very cool. Seems like a good idea. Look for other racing divisions in the US that already allow LS based engines, there aren't many but there are a few.
I'd suggest posting up what is allowed in the "built" SBC, that might help with suggestions.
Im confused, you say this is a list of parts you have began to compile.... but the list looks like you have no other choice but to run what is on the list?
This is a list that I have created. This is set to kind of be a "spec option" rule book, to keep the engines affordable. I guess I worded that wrong. The spirit of this is to allow an average Joe racer to be able to grab an LM7 from a junk yard and do the upgrades necessary to race, in his own garage. Nothing has been purchased yet, the Tech Inspector asked me to come up with a "rule set" for us to start a conversation with the track and look things over.
I also have changed the cam part # to a slightly smaller GM Performance camshaft. My mistake in missing that, I was simply looking for low lift cams and overlooked that note in the description. I went with the smaller camshaft after doing some more researching and looking around this morning finding that Hot Rod had done a cam comparison with a similar TruckMAX Crane 200 dur. cam and made 380hp and 400tq which should be right around the right ballpark.
Very cool. Seems like a good idea. Look for other racing divisions in the US that already allow LS based engines, there aren't many but there are a few.
I'd suggest posting up what is allowed in the "built" SBC, that might help with suggestions.
The "built" engine rules are very open and so hard to judge by. The hope (for me) would be that the LS rules eventually replace the current built SBC rules because there are guys currently spending $12k on these engines.
It's my understanding that trunion upgrades are all about reliability, with no performance benefit. At least that's the case with the LS6, which is the engine I'm most familiar with.
It's my understanding that trunion upgrades are all about reliability, with no performance benefit. At least that's the case with the LS6, which is the engine I'm most familiar with.
So I'd lean heavily toward allowing that.
This is an area I am a little foggy on. I suppose you are right though as I can see the benefits of trunnion upgrade. I will change that. Thank you
Stock rocker bearings do fine in stock situations but in high-lift, high-RPM, and aggressive lobe situations, there have been cases of the little needle bearings getting loose into the engine innards. That's where a good trunnion upgrade come in. And use one of the bronze bushing ones . Straub and CHE are good, though there are others out now too. WS6store has a new kit that does use fully caged needle bearings that looks pretty good too.
Also, do any of you think the Melling High Volume oil pump should be a must for this?
Thank's for the replies and help guys, much appreciated!
If you are running stock lower end with stock clearances, the Melling HIGH PRESSURE pump is what you want. The only time high volume is warranted is with DOD or VVT which needs more oil to operate.
If you are running stock lower end with stock clearances, the Melling HIGH PRESSURE pump is what you want. The only time high volume is warranted is with DOD or VVT which needs more oil to operate.
Got ya, wasn't aware of that. Glad I got a high pressure pump for my Z06 lol
The Achilles heal of the LS platform is the oiling system. It’s not a “priority main” system, and in fact feeds the mains last. Will you allow dry sump systems into the mix? I’m not implying that dry sump systems will be necessary here, and would add big cost to the package. Wet sump systems can be designed to work properly with the right pan and pump.
I ran asphalt late models for a number of years here in Ga. There are currently no asphalt tracks left in Ga, so it’s refreshing to see that the sport lives up in your neck of the woods. And to think that NASCAR started here, makes it more depressing.
The Achilles heal of the LS platform is the oiling system. It’s not a “priority main” system, and in fact feeds the mains last. Will you allow dry sump systems into the mix? I’m not implying that dry sump systems will be necessary here, and would add big cost to the package. Wet sump systems can be designed to work properly with the right pan and pump.
I ran asphalt late models for a number of years here in Ga. There are currently no asphalt tracks left in Ga, so it’s refreshing to see that the sport lives up in your neck of the woods. And to think that NASCAR started here, makes it more depressing.
We are alive and well up here for sure. By last count I believe there were 19 paved oval tracks here in the 6 New England states combined. I also do know there is still one asphalt track in GA, Crisp Motorsports Park.
Dry Sumps are absolutely off the table though. The spirit of the rules is to keep the cost at or under the cost of a 602 gm crate engine. I realistically believe that I could build the engine in my shop as the regular joe schmo that I am for 3000-3500 from bell to accessories, carb to pan. It's basically a stock engine.
Pace performance used to offer a turn key 5.3 setup with dual quads that fell right within your power/torque requirements for $6500, but I no longer see it on their website.
We are alive and well up here for sure. By last count I believe there were 19 paved oval tracks here in the 6 New England states combined. I also do know there is still one asphalt track in GA, Crisp Motorsports Park.
Dry Sumps are absolutely off the table though. The spirit of the rules is to keep the cost at or under the cost of a 602 gm crate engine. I realistically believe that I could build the engine in my shop as the regular joe schmo that I am for 3000-3500 from bell to accessories, carb to pan. It's basically a stock engine.
Gotcha. The engines will require an aftermarket pan with baffling, at the very least, which aren’t cheap, and an oil pump that won’t cavitate the oil at rpm. I’d recommend pushrods with restrictors, and a HP+HV pump to help the bearings live. Personally I’d stay with the open engine option, but I spent stupid money on my program.
Last I heard Watermellon Capital (Crisp) wasn’t running a full schedule, and was failing due to no car counts, which is what killed all the other pavement tracks around here. I thought it was done by now. Great to hear you guys are still enjoying the sport!!
I looked at this one, however in the spirit of the rules, the selected cam is a stock replacement for the later LS1 and LQ9. People could get used cams cheap from those engines if so desired to save some money. I see a number of them floating around frequently.
12-16-2018, 03:23 PM
Working on a Circle Track Street Stock Engine Option... Need some opinions! 
