Page 5 of 5
Re: SBC intake question for the experts
Posted: Mon Jun 25, 2018 12:16 pm
by RevTheory
Carnut1 wrote: ↑Mon Jun 25, 2018 12:07 pm
RevTheory wrote: ↑Mon Jun 25, 2018 11:06 am
I'm guessing trying to burr-finish epoxy is probably a really bad idea, no?
No problem Rev.
That's good news, Charlie. I figured it would fracture the snot out of it.
Re: SBC intake question for the experts
Posted: Mon Jun 25, 2018 12:35 pm
by CGT
RevTheory wrote: ↑Sun Jun 24, 2018 11:58 am
Hyd/roller 225/229 at .050, .650/.590 lift, 109 LSA
Have you found a 225°intake lobe with enough lobe lift to get that lift with a reasonable rocker ratio? That kind of stuff isn't real plentiful, for several reasons. .
Re: SBC intake question for the experts
Posted: Mon Jun 25, 2018 12:39 pm
by RevTheory
CGT wrote: ↑Mon Jun 25, 2018 12:35 pm
RevTheory wrote: ↑Sun Jun 24, 2018 11:58 am
Hyd/roller 225/229 at .050, .650/.590 lift, 109 LSA
Have you found a 225°intake lobe with enough lobe lift to get that lift with a reasonable rocker ratio? That kind of stuff isn't real plentiful, for several reasons. .
Comp QXI with 1.65 rockers, which I've been told ratio out closer to 1.69 but I haven't mapped it myself. I'm cool with less if that's how it works out. Now whether or not that's a good idea is yet to be determined
Edit: It's a pretty damn aggressive lobe that I haven't completely talked myself into. I could always do the "glory pull" and drop rocker ratio once it goes in the Jeep.
Re: SBC intake question for the experts
Posted: Mon Jun 25, 2018 1:05 pm
by 6.50camaro
Not an expert here ,but . Maybe GM was targeting the market that would use retro-fit style throttle body efi . I have never used these but have heard of them not being effective on a dual plane intake? Just my 2 cents .Dan
Re: SBC intake question for the experts
Posted: Mon Jun 25, 2018 1:58 pm
by 67RS502
Why would I care what it makes at part throttle?
A cam can make it less streetble at part throttle, but an intake wont! (not dual or single plane anyway)
If youre worried about part throttle keep the duration short, that will make way more diff than the intake type, for the street croud.
So what if it spends 90% of its time putting around the street below 4000…
I want it to fly when I’m on it 5000-7000, could care less if it makes 350tq at 3500 or 375tq at 3500!
The other thing is most cars wont hook on the street anyway, so forget about et, I want that mph… which comes from hp = single plane.
I can guess from the but dyno what a car will run within 1-2 tenths, maybe its just me, but more mph always feels faster on the street,
and will “pull” on the car in the other lane (and more mph at the strip)
And this is coming from a guy with a 224 cam 383 with a dual plane… which was just for the sleeper effect.
Because I know it would be faster with the right cam and a single plane.
Most of these GM crate motors are miss-matched anyway… low compression, single plane, lots of junk rotating assemblies, no cam, may as well just build one yourself.
Just my 2 cents worth.
Re: SBC intake question for the experts
Posted: Mon Jun 25, 2018 2:08 pm
by Frankshaft
67RS502 wrote: ↑Mon Jun 25, 2018 1:58 pm
Why would I care what it makes at part throttle?
A cam can make it less streetble at part throttle, but an intake wont! (not dual or single plane anyway)
If youre worried about part throttle keep the duration short, that will make way more diff than the intake type, for the street croud.
So what if it spends 90% of its time putting around the street below 4000…
I want it to fly when I’m on it 5000-7000, could care less if it makes 350tq at 3500 or 375tq at 3500!
The other thing is most cars wont hook on the street anyway, so forget about et, I want that mph… which comes from hp = single plane.
I can guess from the but dyno what a car will run within 1-2 tenths, maybe its just me, but more mph always feels faster on the street,
and will “pull” on the car in the other lane (and more mph at the strip)
And this is coming from a guy with a 224 cam 383 with a dual plane… which was just for the sleeper effect.
Because I know it would be faster with the right cam and a single plane.
Most of these GM crate motors are miss-matched anyway… low compression, single plane, lots of junk rotating assemblies, no cam, may as well just build one yourself.
Just my 2 cents worth.
I have been trying to beat this into guys heads, but they don't seem to get it. But I agree 100%
Re: SBC intake question for the experts
Posted: Mon Jun 25, 2018 2:47 pm
by paulzig
6.50camaro wrote: ↑Mon Jun 25, 2018 1:05 pm
Maybe GM was targeting the market that would use retro-fit style throttle body efi .
It is pictured with a carburetor and sold as a 'turn key' option so I fail to see how they target it for use with a TB style efi system. Is it just because its a single plane that you come to this conclusion?
Re: SBC intake question for the experts
Posted: Mon Jun 25, 2018 2:49 pm
by paulzig
67RS502 wrote: ↑Mon Jun 25, 2018 1:58 pm
Because I know it would be faster with the right cam and a single plane.
What about keeping the same cam and a single plane? Easier to try than going into the engine...
Re: SBC intake question for the experts
Posted: Mon Jun 25, 2018 3:04 pm
by 67RS502
I was just trying to say that it has the wrong cam and intake to make power / be fast.
I believe it would be faster with either one or both changes.
But it was tempting to throw a single plane on it to see what happens, the heads are big, so more rpm would have been in order.
Re: SBC intake question for the experts
Posted: Mon Jun 25, 2018 3:14 pm
by paulzig
67RS502 wrote: ↑Mon Jun 25, 2018 3:04 pm
But it was tempting to throw a single plane on it to see what happens, the heads are big, so more rpm would have been in order.
The single plane on its own might give you the RPM without the cam.
Re: SBC intake question for the experts
Posted: Mon Jun 25, 2018 3:43 pm
by 67RS502
Yes, the single plane would.
I'd shift the RPM intake around 6400-6500, so a small single plane (with the large heads) would need upper 6000 shift points I believe.
A decent cam would need low 7000 shift.
I do think it would be faster with either change.
Re: SBC intake question for the experts
Posted: Mon Jun 25, 2018 3:54 pm
by paulzig
67RS502 wrote: ↑Mon Jun 25, 2018 3:43 pm
Yes, the single plane would.
I'd shift the RPM intake around 6400-6500, so a small single plane (with the large heads) would need upper 6000 shift points I believe.
A decent cam would need low 7000 shift.
I do think it would be faster with either change.
You'd get accused of an intake manifold/camshaft RPM range mismatch...
224@50thou 5000RPM range camshaft with a 7500RPM range super victor.