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My Engine Build Thoughts - Give me your input

2K views 19 replies 5 participants last post by  vinniekq2 
#1 ·
Going in our Wingless Sprint car. Give me your thoughts or suggestions. Thanks

SBC 350 +.060

ROD: Lunati 6"

CRANK: Scat 3.75 Stroke

PISTON: SRP
Piston Style: Dome, with two valve reliefs
Piston Material: Forged aluminum
Compression Distance (in): 1.125 in.
Piston Head Volume (cc): -7.00cc
Wrist Pin Style: Press-fit or floating
Pin Diameter (in): 0.927 in.
Piston Ring Thickness: 1/16 in. x 1/16 in. x 3/16 in.
Notes: Oil rail support included.

CAM: Howards Cams
Mechanical Roller Tappet
Basic Operating RPM Range: 4,200-8,000
Intake Duration at 050 inch Lift: 261
Exhaust Duration at 050 inch Lift: 265
Duration at 050 inch Lift: 261 int./265 exh.
Advertised Intake Duration: 293
Advertised Exhaust Duration: 297
Advertised Duration: 293 int./297 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.620 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.620 in.
Valve Lift with Factory Rocker Arm Ratio: 0.620 int./0.620 exh.
Lobe Separation (degrees): 108
Camshaft Gear Attachment: 3-bolt
Intake Valve Lash: 0.022 in.
Exhaust Valve Lash: 0.022 in.

HEADS: AFR
227cc Raised Intake Runners
59cc Combustion Chambers
2.100 Intake Valves
1.6 Exhaust Valves
Howards ProMax Mechanical Roller Lifters

ROCKERS: T&D Shaft 1.5

INDUCTION: Hilborn 2-7/16" Mechanical Injection (Alcohol)
 
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#3 ·
Please tell me you're not using a stock block. You have some nice parts that may be able to make some nice power- but a stock block will never last with that.

Also, JMO, but I'd go easier on the cam lobes and increase the rocker ratio- unless you're running a much larger than stock cam core, which you may be.
 
#4 ·
ap72,those are standard lobe sizes for that type of roller cam. I use shaft rockers for my street car,netting 640/600 ish actual lift after adjustment for solid rollers.
for 8,000 rpm shafts are almost essential.
To get bigger than 420 lift lobes,usually you go for the block that takes a bigger cam in the raised position.
 
#11 ·
They may be "standard" but those lobes and the spring pressures they require are going to severely stress out a stock size core. One of the sbc's biggest faults in stock form is the tiny cam core, the other is the port arrangement.

An SHP or SHP Pro block will allow you to step up in core size- I definitely would to get more stability and less wear.
 
#5 ·
Vinnie,
The heads are race ported from AFR. My main concern was using the dome piston with the small chambered heads but the dome is not that much so it should be fine. I'm figuring about 14:1 SCR with those pistons and heads which should be great for alcohol.

AP72,
I'm hoping to get a Dart SHP block for this build.
 
#13 ·
flat top pistons have a better flame travel giving you a better complete combustion of fuel, that in turn equals more hp and better flow. plus what you lose in compression from not having the dome you can make up for in your gasket if you want

put a really good 9 way adjustable timing set in it so if you need you and take that 108 cam down around 102 to 100 if needed for banking.

use a electric water pump and a crank driven fuel pump with a emergency shutoff and by-pass

use a magneto for ignition, you going to need all the output and reliability you can get

if you don't have the hilborn yet, I would you a duel rons flying toilet injection, more reliability and better adjustability plus its not remanufactured from 40 year old parts and will cost you the same money
 
#17 ·
Fire slotting domes with Alky gives you a better solution.

I agree with everything else you posted.The thing with Hilborn is it is a combo between the balance/set-up of the car,the gearing of the car per track,and the correct pill size.A weather station and a log per track helps.Depending on how sharp of a tuner you are,that data might take sometime to gather.You want to change one element at a time.Read the plugs constantly.Leakdown every wk as apart of normal maintenance.Valve lash every wk.Catch a problem before it becomes one.Good data will pay-back a thousand times over.Open up the ring gap the same way you would with any other power adder.

We have never used a aftermarket block in any of our 9.90 or 10.90 cars where in both we have used Alky. They get freshen up at the end of the season along with the above routine.
 
#16 ·
I know, this stuff is expensive. Do you think FT pistons would work best instead of domes with the 59cc heads? I done a compression calculation using 2VR FT pistons and only came up with around 11:1 which I'm not sure alcohol will like. That was using a .040 compressed head gasket thickness though, I could go thinner I suppose.
 
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