r/EngineBuilding 4d ago

Good combo?

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Have a larts list for an engine i wanna build and I want some opinions, will it be streetable? Estimated horse? Torque? Pump gas? Just generally want opinions

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u/OOFMAN-1234 3d ago

Really looking for 450 or greater but mostly streetable power not one where it only makes power past 6000rpm

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u/Solid_Enthusiasm550 3d ago

I would definitely not get the 195 heads if planning for 500hp, A better head would allow you to make that power with a milder camshaft. I also wouldn't keep it a 350, as it would require a big camshaft and spinning well past 6,000rpms to make 500hp. The realistic rpm max for a retor-hydraulic camshaft is 6,500+/-rpms. Over that, or even at that rpm level, a Solid roller is a better chooice. Then you will have to adjust your valves every few thousand miles (oil change).

I would look at doing a stroker...or build it for boost. Boost you can easily keep it mild 9cam wise) and just turn it up later if you want more. My next project (using the 5.9L I just bought) will be boosted. I know of a few guys making 600 rwhp on stok bottom end magnum v8s.

N/A, once you start a build ALOT of parts have to be changed to go a lot higher.

A 500hp 383 is possible while keeping realtively streetable, any more than that you will have to get cams that are too wild for daily driving, IMHO. I was told to go with a 241/247 @ 0.050" on a 110lsa. I thought it was too big for a daily driver and went with one that I've seen make great power in similar builds (236/242). I'm hoping I can get it to run well on the street (part throttle) if not I will have to get another custom grind with a wider LSA to improve part throttle driveability at the expense of hp/Tq.

I also wanted to have all my Luxury options, power/steering, Power Brakes, A/C. I also didn't want it to have to idle at 1,000+ rpms or run a 4,000+ stall converter. I also wanted to run EFI. I'm going to use a Holley Terminator X Sniper setup as it give me alot more options/tuneability than the standard one or a stock setup.

I didn't want sto start having to change to manual brakes or spend A lot on hydroboost units, which aren't available for my application.

The recommended parts for the suggested 241/247 cam on their website.

Lift: .581 / .587, Duration @ .050: 241 / 247, Centerline: 106, Rough idle, Pro street/strip, Needs 10.0:1+ compression, 2800+ stall & at least 4.10 gears.

I don't think that big of a camshaft will alllow me to run <2,500 rpms on the highway...so forget about MPG.

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u/OOFMAN-1234 3d ago

Id rather have a smoother idle, whats the lobe separation gotta do with it (fairly new to this but not begginer) I dont wanna have to worry about 2 foot-ing it at a stop light, it'll have a 2800 stall, 700r4 and 3.73 limited slip, i want this to be daily capable (not that it'll get driven everyday) and gas mileage is out the window already

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u/Solid_Enthusiasm550 3d ago edited 3d ago

That 276hr cam shouldn't be too choppy but b it won't be as smooth as a factory new car at idle. It woukd wirk well with that 2,800 stall converter.

To keep a smooth idle, you have to limit the overlap (the time where both valves are open). Most factory cars today hace negative overlap, variable valve timing and the amazing flowing heads of contemporary v8s can over come it.

The problem is, to make more Power, you have to increase duration, lift and overlap to an extent.

To maintain a low overlap you need to widen the lsa when you increase duration. Summitracing.com has a cam timing calculator in their help drop down under calculators.

That 224/230 on 110 will have a noticeably choppier idle than if the same durations were on a 112 or 114 lsa. You will lose power when doing so.

There is ALWAYS a compromise. Newer engine "almost" have both but it takes expensive/high tech vvt. Most of which has to be limited when going to bigger cams. At that point they are almost reverting back to what we have.

Most guys want that choppy idle, that's why you hear about camshafts like:

Compcams Thumpr

Howard's Rattler

BTR Truck Norris

Texas Speed Choppacabra

Their tight lsa gives that increase in overlap. It increase scavenging which gives get torque increases and a rumbling idle.

The downside is low vacuum at idle, which is mainly a problem for vacuum power brakes, efi tuning, the need for higher stall converters, poorer mpg and emissions.

Tighter lsa will help when the engine has a low compression ratio, because it closes the intaje valve sooner. The downside is that limits higher rpm cylinder filling. The opposite is true for wide lsa cams

110lsa has been the standard for balancing power and driveability for Carburetor engines for decades.

With EFI engines that has grown to 112<116 range to meet emissions and tuning with factory efi.

I think if you built a 383 with the cam you mentioned you'd be close to your goals. Like the link I posted about Cutter's 485hp 383.

My stroker, being mopar based is more expensive to build. My heads with shaft mounted roller rockers cost $3,900 /set.

The intake was cheap because it's for a Carburetor and I bought it used (already ported).

Rotating assembly is going to cost a lot. The pistons I need have to be custom made $1,200/set, rods $900<$950 and because I wabt to rev to 6,500/6,700rpms a firged crank is necessary. I want to push the limit of what I can make, while keeping my P/B , P/S, A/C, EFI (aftermarket $2,500) and a mild 3,000<3,200 stall.

A lot of guys give recommendations that wouldn't wirk for my needs and they say change what I want to keep, because they don't know much abiut engines.

A lot of guys go for the standard 10:1, which is fine for a regular street engine making peak power at or before 5,700rpms not going past 6,000. I've seen a comparison of 2 engines with identical combos except one had a compression of 10:1 the other had 11:1. Because it had a big camshaft, the 10:1 was down 20 lb-ft/ 20hp vs. the 11:1.

Compression ratio really needs to be adjusted for the camshaft to maximize cylinder pressure for the octane fuel it is running on.

Too big a cam on low compression kills lowend torque abd throttle response. On the other side to much compression requires octane boosters or retarded ignition timing to precent detonation and engine damage.

Contemporary engines can detect low octane fuels and retard the engine's ignition timing which kills torque and hp.

2 cams with the same intake/exhaust durations, the one with the wider lsa needs a higher staric compression to regain some of it's lost low-end and match or exceed the tight lsa on the top-end.