434 engine upgrades ?

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Re: 434 engine upgrades ?

Post by af2 »

Monza355 wrote: Sun Jul 18, 2021 7:55 am
PRH wrote: Sat Jul 17, 2021 8:07 pm I’d start with having the manifold ported........ maybe have the heads looked over/flowed/touched up.......and set up for about .700 lift........ and get a new cam.
It’s a viable option to port the intake manifold. But it looks plenty big. Especially compared to it’s 4150 counterpart.

The heads do have 240 lbs seat pressure springs that are supposed to be good for .700” lift
Just letting you know The mods I did corrected the fuel and ran way faster with that intake. I have the intake off because I have a Kinsler on it now.

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Re: 434 engine upgrades ?

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Monza355 wrote: Fri Jul 16, 2021 5:45 pm Hello. A friend if mine has a 434 ultra street engine from Scott Shafiroff. It’s a good engine with decent parts but we are hoping we might be able to pick up some power. Maybe with a camshaft upgrade. The engine was sold as a pump gas engine back in the day but with 11.5:1 compression ratio it’s picky on fuel. We have been running it with 100 octane avgas and that works very well.

The engine is a flat top 434 w 11.5:1 compression
Brodix 227 T1 sts cnc ported heads
World Motown 4500 intake and a 1050 cfm Dominator
Solid roller camshaft
254/258 @.050” .634”/.634” lift w. 1.6 rocker arms .396” lobe lift, 109 LSA.
It was supposed to be around 620 hp


The engine is in a 3500 lbs Camaro on 28” tires with 3.89 gears and th400 transmission with 5000-5500 8” converter. It currently runs high 10’s at 126 mph
And for what its worth that cam is small on both sides..
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Re: 434 engine upgrades ?

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Why not just spray it? It will accomplish your goal without changing anything else.
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Re: 434 engine upgrades ?

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rustbucket79 wrote: Sun Jul 18, 2021 6:49 pm Why not just spray it? It will accomplish your goal without changing anything else.
I’m sure it will be sprayed some day. But this engine isn’t going to carry the power up to 7000 rpm’s as is. It makes peak power at 6100 rpm as is if i remember correctly.

I agree the dominator may be overkill for this combo. It was just a part of an upgrade available at the time. Called Saturday night special or something like that. It is a good engine. It has a Little M block and Callies crank and rods with Mahle flat tops.

I still like the Intake mod af2 recommended. I think that along with a better suited camshaft must pick it up. I’m sure a little lower gear will help as well. But then the engine must turn the rpm’s
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Re: 434 engine upgrades ?

Post by rustbucket79 »

The intake isn’t the cork, FWIW we finished up a 427 recently with AFR 235’s, topped with an untouched 4150 version Motown intake the customer wanted to use, street engine. It made 618 (corrected) and peaked at around 6600 with a cam very close to yours.

Get with a cam company to sell you a cam more suited to where you want to be (no you don’t need pro stock duration numbers) and plan to have those heads rubbed on either now or in the future, or perhaps step up to a larger head, and you’ll get where you want to be.
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Re: 434 engine upgrades ?

Post by Mark O'Neal »

I am sorry...but I do not see 434 engine upgrades here......
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Re: 434 engine upgrades ?

Post by Mark O'Neal »

rustbucket79 wrote: Sun Jul 18, 2021 6:49 pm Why not just spray it? It will accomplish your goal without changing anything else.
I agree...because nitrous oxide is the best thing that ever happened to piston manufacturers.
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Re: 434 engine upgrades ?

Post by mt-engines »

Si ce the engine must turn RPM. You need a bigger head.

You can port them, put bigger valves minimum... add at least 10 degrees of duration on the cam. And as much lift as you can get away with.

If it were me. Id be looking at a 250cc head keep the dominator and port the snot out of the intake. The carb is fine.

You can cam it for more RPM now. But you won't be picking up much power.
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Re: 434 engine upgrades ?

Post by GARY C »

Mark O'Neal wrote: Mon Jul 19, 2021 3:52 am
rustbucket79 wrote: Sun Jul 18, 2021 6:49 pm Why not just spray it? It will accomplish your goal without changing anything else.
I agree...because nitrous oxide is the best thing that ever happened to piston manufacturers.
Seems to be more of a tuning problem and less of a nitrous problem. seen it more with alcohol dirt track engines. I started running nitrous in 1997 and the only issue I have seen is cap walk on 2 bolt applications with larger shots like this 357 engine.
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Re: 434 engine upgrades ?

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This is the car we ran a 306, 377, 382 and 421 in, the vid is running the 421.
https://www.youtube.com/watch?v=6RgKOCo0GhU
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Re: 434 engine upgrades ?

Post by Orr89rocz »

Abit of head work and atleast 10 more degs duration will likely get you where you want to be. As others said
434 is a good bit of cubes they really like some port area
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Re: 434 engine upgrades ?

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Orr89rocz wrote: Mon Jul 19, 2021 9:45 am Abit of head work and atleast 10 more degs duration will likely get you where you want to be. As others said
434 is a good bit of cubes they really like some port area
Yes it sounds like a new cam is in the works. I will tell him to contact some knowledgeable guys like Mike Jones for input on what to do.

With the components listed the engine would probably be better as a 406. It does however have pretty good midrange power as is.
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Re: 434 engine upgrades ?

Post by PRH »

Back when I was still doing complete motors........ this is one of those jobs that if it showed up on my door....... with the reason it was here being to try and extract more power out of it....... it would get tested just as it was when it showed up.

I’ve tested plenty of motors built by various other shops where the numbers were well below what the dyno sheet they came with said.
Often times, had the motor actually made what was on the dyno sheet..... the owner would have not been looking for more power.
Somewhat handy with a die grinder.
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Re: 434 engine upgrades ?

Post by Monza355 »

PRH wrote: Tue Jul 20, 2021 4:43 pm Back when I was still doing complete motors........ this is one of those jobs that if it showed up on my door....... with the reason it was here being to try and extract more power out of it....... it would get tested just as it was when it showed up.

I’ve tested plenty of motors built by various other shops where the numbers were well below what the dyno sheet they came with said.
Often times, had the motor actually made what was on the dyno sheet..... the owner would have not been looking for more power.
That’s a vice move to do. I don’t think this particular engine makes 620 hp or what it was supposed to make. And probably not the 600 ft-lbs it was supposed to be as well. I however think we can pick it up a bit. And that’s what counts in our case.
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Re: 434 engine upgrades ?

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Monza355 wrote: Sat Jul 17, 2021 6:19 pm
CamKing wrote: Sat Jul 17, 2021 11:49 am What RPM do you want to turn it ?

We were thinking about turning it up to 6800-7000 rpm.

The tall-ish gears are in it because he had plans on running little nitrous on an occasion. Maybe 1-2 times per season. But the converter came out looser than we thought it was going to be. So it has never been sprayed. So going with a lower gear ratio is an option at this point.

The headers are 1.7/8” to 3.5” collector.
He also said it has ran a best of 128 mph and is around 6500 rpm’s in the traps
Your current cam is making peak HP around 6,100rpm and should be falling off hard after 6,500.

This cam would make peak HP, at 6,600, and pull to 7,000rpm. I calculate 640hp.
Cam# SBC, R78440-80440-110
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.440"/.440" Lobe Lift
110 LSA
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