Gents (Gals?),
Wanted to get some feedback on my project and see what is your feedback on the good, bad and ugly. Everything is pretty much bolted as far as the engine goes, just waiting on Manton for the pushrods.
The overall combo.
Short Block: Stock LS7 (4.125 x 4.00) (Titanium Rods)
Heads: Stock LS7 (CNC ported by TSP + “swirl dam” removed by hand)
Heads Configuration: PSI1516 Springs(150/420lb 409 Rate set at 1.786/1.785 E/X (.050 CBC); Stock 1.8 rockers w/Straub Bushing Kit; Manton 3/8 X .120 Pushrods; Stock Ti-Intake Valve; Stock Hollow Stem Exhaust valve; Valve train weight (valve, spring, keeper, locks) 149g Intake and 147g Exhaust.
Intake: MSD "Airforce" ported and modified runners (shorter) from 9.3" to 7.4" with epoxy bellmouths
Trottlebody: NW 102mm
Compression: 12:1; ~.035 quench
Fuel: E85, FIC 850cc Injectors and Walbro 450 E85 Pump
Lifters: Johnson 2110 (set at .040 lash)
Cam: Ground by Cam Motion
Intake open BTC -15.5
Intake close ABC -53.5
Exhaust open BBC -66
Exhaust close ATC -12
Intake center -109
Exhaust center -117
Degrees overlap -27.5
Headers: ARH 2” Primary, 3” Collector, X-Pipe no-cats
Damper: ATI 10% UD
Clutch/Flywheel: McLeod Dual and Aluminum Flywheel (33lb total weight)
The narrative (key points) that articulates the “risk” within this combination is that I did the following:
• Intake Manifold: MSD “Airforce”, I took and modified the runners from a stock length of 9.3” into 7.4” (I was looking to reduce 2”) I contoured bell mouth radiuses out of A-B epoxy.
• Heads: Heads have been CNC ported, PLUS after the CNC -I eliminated the swirl fin on the intake (yes, huge risk)
The reasoning behind the “shorter runner” MSD is that I was looking to something similar in performance to the HOLLEY Hi-Ram without having to cut my hood or spending quite a bit extra cash on a sheet metal intake. So, making my own was the only option. I wanted to move up my peak power into the 7300-7500 RPMs.
So, what you guys think? Power/RPM? What would you have changed?
Tell me about my combo!
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Tell me about my combo!
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"Bring it!"
Re: Tell me about my combo!
Hello,
If your hp goal is ~650 flywheel, you are there. I am not familiar with that manifold and am curious how you derived at the port length. Pipemax?
Can you shoot a pic of the top side of that intake manifold? Have you approximated the cu in of the plenum?
I might have missed it, do you have a minimum rpm that you want this combination to work with? Is it a street car or only track with certain RPM ranges in mind? The exhaust has to be just as tuned as the intake to widen the powerband. Calvin Elston, here, is one of the pros, yours seems fine for 5000 rpm and up but if you need to help the lower rpm ranges, the exhaust design is critical or it will be a dog till it "gets on the pipe"
The cam numbers seem like a hyd roller, a little too early intake closing event, in my opinion, to make power upstairs like you want.
You can't weigh the valvetrain as a whole, it's all separate and the spring is a dynamic. It's a start but it's also like saying a 23 degree sbc head at 230 cc intake port is the same as the next guys 230cc intake port.
I would like to hear more details
If your hp goal is ~650 flywheel, you are there. I am not familiar with that manifold and am curious how you derived at the port length. Pipemax?
Can you shoot a pic of the top side of that intake manifold? Have you approximated the cu in of the plenum?
I might have missed it, do you have a minimum rpm that you want this combination to work with? Is it a street car or only track with certain RPM ranges in mind? The exhaust has to be just as tuned as the intake to widen the powerband. Calvin Elston, here, is one of the pros, yours seems fine for 5000 rpm and up but if you need to help the lower rpm ranges, the exhaust design is critical or it will be a dog till it "gets on the pipe"
The cam numbers seem like a hyd roller, a little too early intake closing event, in my opinion, to make power upstairs like you want.
You can't weigh the valvetrain as a whole, it's all separate and the spring is a dynamic. It's a start but it's also like saying a 23 degree sbc head at 230 cc intake port is the same as the next guys 230cc intake port.
I would like to hear more details
Heat is energy, energy is horsepower...but you gotta control the heat.
-Carl
-Carl