High RPM - Which Platform - Team Camaro Tech
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post #1 of 19 (permalink) Old Jul 6th, 15, 12:53 PM Thread Starter
 
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High RPM - Which Platform

Ok I know I'm new here, but I do know how to use the search button and I've spent the better part of my holiday weekend using it, reading and learning. I also reached out to a couple local engine builders, and reached out to NRE.

What I thought I want (I still kinda do): a stoutly built DZ302 (using words like aluminum, forged, balanced, and maybe even titanium) to be a regular weekend driver and rev in the low to mid 8k rpms safely and reliably.

Now, as this is widely debated and discussed, I've been told "you won't like it" because this type of engine needs to live above 5500 rpm to make any power and that's not real world street use reality.

However, I've built a 383 Stroker, I've built a 350 LT1, I have a twin turbo inline 6; I know what power and torque feel like (feels great!) but I'm in the mood for the symphony that only an N/A V8 at high rpm can play.

Is there another engine, not a DZ302, that I should be considering as a candidate to achieve my goal? I'm okay driving around town in the 3k-5k range with 200-250 hp 80% of the time if I get to spend 20% of the time screaming on the backroads and canyons. I also come from a motorcycle racing background, so I'm used to that feeling of no power until the last 3k of available rpm.
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post #2 of 19 (permalink) Old Jul 6th, 15, 01:14 PM
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Re: High RPM - Which Platform

Answer no. 1 is: I doubt you will find a better platform to start with. I wouldn't worry about a DZ coded block. Any good four bolt early (two piece seal) will do.

I helped build a 302 (68) back in HS in the late 60s. We used the off road cam (commonly called the 140 cam) and the 142 springs. Pinned the studs. No port work whatsoever on the stock 2.02 heads. Small tube headers. It regularly saw 8200 rpm and never came apart.

You can do this with all vintage GM parts, it that is important to you, but you can do better with modern parts.

If trying to emulate that car today, I would go with a roller cam and screw in studs.
Unless you MUST have period correct heads, I would go with a good aftermarket aluminum heads (lots to choose from) and get someone like Chris Straub to do the camshaft AFTER you decide on your heads. Go for about 10.5 to one compression. I would NOT use the factory style dome piston (2nd design) with the single trough type valve relief.

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post #3 of 19 (permalink) Old Jul 6th, 15, 02:18 PM
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I have heard that a 377 is quite similar to a 302. The 377 is a 400 block and a 350 crankshaft with bearing spacers.

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post #4 of 19 (permalink) Old Jul 6th, 15, 02:26 PM
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Re: High RPM - Which Platform

It's really all in the valvetrain, regardless of motor size. A soundly built bottom end and decent heads and it will be a blast to drive.

If you want a 302 just because, cool, I'd do it. Otherwise maybe bump the inches up a bit, like a 3.25 stroke (ie 327). You won't need anything magic for a bottom end, just decent parts and assembled correctly.

Then get a good set of heads, don't bother with old factory castings unless that's what you want to do. A decent set of aluminum heads, and I would spend the money on your valvetrain. The cost of shaft rockers makes it the only way to go, and you won't have issues there.
If you run a big intake valve Ti is really nice, but for 8k not absolutely mandatory with a smaller valve, like maybe 2.05 and less? (Talk to a cylinder head guy). With a 4.00 bore you'll be limited anyway. The springs are important (based on cam) and run a lightweight steel retainer, they are more durable than Ti and nearly as light.

Contact a good cam designer for a cam, the right cam can make lots of power and not destroy valve parts. Worth the money for sure.

Want ideas on other options? It's not the easiest or cheapest (though not stupid expensive either), try using SB2.2 heads, and build something in the 350" range, large bore short stroke. I just did this, I have a 354" SB2.2 in my Camaro, 3.25" stroke, 4.155" bore. It runs on pump gas (big dish) and screams. Makes quite a bit of power too.
I have been driving it around a lot getting the feel of it and it really cruises easily, slightly rough off idle but nice and smooth at cruise, and wicked under full throttle. The cam is designed to shift at 7800-8000, and it's all I can do to get the shift off before the limiter (automatic too..) It's a blast.

Just remember running it up to 8k and making power to 8k are two different things.

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

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post #5 of 19 (permalink) Old Jul 10th, 15, 09:21 AM
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Re: High RPM - Which Platform

I just pulled out my DZ302 for a high compression solid roller 372ci small block. The 302 feels like a 4 banger compared to this thing. Everybody says you can't run a motor like this on the street, but mine will putt around town just fine at 2,200 rpm with 13.6:1 compression, 268/[email protected] camshaft, and a 950 cfm double-pumper. It makes 8" of vacuum and works the power brakes and PCV just like stock. Here is a video of the dyno pull...

https://www.youtube.com/watch?v=D2O0ROhmUhU
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post #6 of 19 (permalink) Old Jul 10th, 15, 09:45 AM
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Re: High RPM - Which Platform

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Originally Posted by Neil B View Post
I just pulled out my DZ302 for a high compression solid roller 372ci small block. The 302 feels like a 4 banger compared to this thing. Everybody says you can't run a motor like this on the street, but mine will putt around town just fine at 2,200 rpm with 13.6:1 compression, 268/[email protected] camshaft, and a 950 cfm double-pumper. It makes 8" of vacuum and works the power brakes and PCV just like stock. Here is a video of the dyno pull...

https://www.youtube.com/watch?v=D2O0ROhmUhU
Not on pump gas???

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post #7 of 19 (permalink) Old Jul 10th, 15, 09:59 AM
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Re: High RPM - Which Platform

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Not on pump gas???
No. Sunoco 110 for my build. Not an issue for my car's usage. But you could do something similar on corn. Or a pump gas/E85 LSx with big heads and a solid roller would be fun too.
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post #8 of 19 (permalink) Old Jul 10th, 15, 02:49 PM
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Re: High RPM - Which Platform

I think pretty much any motor can be built to spin to the moon, even a big block.
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post #9 of 19 (permalink) Old Jul 10th, 15, 06:25 PM
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Re: High RPM - Which Platform

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Originally Posted by bigblockragtop View Post
I think pretty much any motor can be built to spin to the moon, even a big block.
X2

My 496 BBC wont quite spin to the moon, but it will regularly bounce of the 7400 rpm rev-limiter without any issues and the mid-range torque of the 4.25" crank will be like night and day compared to the 302.

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post #10 of 19 (permalink) Old Jul 10th, 15, 09:18 PM
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Re: High RPM - Which Platform

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Originally Posted by Neil B View Post
No. Sunoco 110 for my build. Not an issue for my car's usage. But you could do something similar on corn. Or a pump gas/E85 LSx with big heads and a solid roller would be fun too.
A pump gas 302 vs a 13.5:1 372, I would hope there is a noticeable difference....lol

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

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post #11 of 19 (permalink) Old Jul 10th, 15, 09:22 PM
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Re: High RPM - Which Platform

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Originally Posted by bigblockragtop View Post
I think pretty much any motor can be built to spin to the moon, even a big block.
Bingo. Short stroke will be easier to make into an rpm motor, and it will also want to be in the upper rpms, a big stroke needs stronger parts in the bottom end typically but is just as capable. As I mentioned earlier, its in the valve train.

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

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post #12 of 19 (permalink) Old Jul 10th, 15, 09:32 PM
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Originally Posted by 71454Chevelle View Post
X2

My 496 BBC wont quite spin to the moon, but it will regularly bounce of the 7400 rpm rev-limiter without any issues and the mid-range torque of the 4.25" crank will be like night and day compared to the 302.
I Agree cubic capacity gets you moving (Torque).

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post #13 of 19 (permalink) Old Jul 12th, 15, 08:53 AM
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Re: High RPM - Which Platform

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Originally Posted by bigblockragtop View Post
I think pretty much any motor can be built to spin to the moon, even a big block.
True, except that you have to have enough cylinder head to support RPMs for a given displacement. This is easier to do with a big block than a small block. If you're staying with a traditional 23 degree small block cylinder head, it gets harder to make 400+ ci engines really scream due to the limited cylinder head intake runner cross-sectional area. Now if you've got the budget for 18 degree heads, offset lifters, and shaft rockers, then by all means build a big inch screamer....or go LS. I think an 11.5:1 pump gas 427 LSx with 245cc heads and a [email protected] cam would be tough to beat. 7,500 rpm and 650+ hp all day long.
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post #14 of 19 (permalink) Old Jul 12th, 15, 01:11 PM
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Re: High RPM - Which Platform

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Originally Posted by Neil B View Post
True, except that you have to have enough cylinder head to support RPMs for a given displacement. This is easier to do with a big block than a small block. If you're staying with a traditional 23 degree small block cylinder head, it gets harder to make 400+ ci engines really scream due to the limited cylinder head intake runner cross-sectional area. Now if you've got the budget for 18 degree heads, offset lifters, and shaft rockers, then by all means build a big inch screamer....or go LS. I think an 11.5:1 pump gas 427 LSx with 245cc heads and a [email protected] cam would be tough to beat. 7,500 rpm and 650+ hp all day long.
If you go 18 degree then you have to consider SB2 also, it might be a touch more money but there are some real good deals out there on them. And they will smoke an 18 degree wedge head. They will work real well on a larger cube motor also. Pistons and intake are different anyway.

If looking for a excellent head that thrives on rpm, its worth a look.

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

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post #15 of 19 (permalink) Old Jul 17th, 15, 07:46 AM
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Re: High RPM - Which Platform

Good greif how many 283's powered everything from 57 chevy's to PU trucks to Corvettes?
Phord's 302 with the smae bore and stroke seems to live on and is stretable.

The 67/68 302 was a destroked 365hp/327. In 69 the DZ got 4 bolt mains, the 2.45/2.10 journal crank and the good 3/8" bolt rods used in the 350.
In stoke form the original 283 and 302 couple buzz 8,000 rpm/ It didn't make power up there but it could do it.
Todays heads would make a LOT more power and at higher RPM's than the old ported stock head days.

Vortec headed mildish (for a) roller cam "DZ" shortblock with Scat cap screw rods would be an excellent hi-RPM street motor.

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