9.5:1 SCR 434 potential

[xxdabroxx]

Humor me a bit here, I'm wondering if I can make as much or more power in a 9.5:1 compression 434 than I'm currently making on my >13.5:1 383 with the same top end.

This stems from wanting to build a roots blown SBC that's pushing close to 1000hp in the future on E85. But that's going to take a while to acquire. So I was thinking what if I got the short block for the blower motor and throw my current heads/ intake on it and run it on pump gas for a while before I'm able to get the blower, carbs, etc.

I think I'm making about 600ish HP running a best of 10.38 @ 129mph in a 3,530 lbs car (if the antique scale at the track is correct)

780 cfm E85 4150
Older 2925 Super victor
Victor Jr 23* 215cc heads (2.08/1.60)
1-7/8" Hooker super comps

Do you think a 9.5:1 434 with the above top end (different carb is an option) make 650ish HP on 91 octane?

[mag2555]

In a nut shell the 434 will make the same hp but at a much lower rpm and that’s due to the torque peak now coming in at a lower rpm even though the bigger motor will be making a higher level of torque the the smaller motor did.

The question then now becomes how much the faster rev nature of the high comp small cid motor was bringing to the table?

Also a rear gear change should take place I would say.

Also keep in mind that once any NA motor has hit its rpm of peak torque that at that point its breathing potential ( all the things that combine to make that up ) has been used up!

[lefty o]

probably 550ish.

[af2]

That 383 must be flippen fast. Don't have a clue how 54ci with less compression is going to be faster NA..

[xxdabroxx]

I was thinking the compression ratio would kill it.

Thanks AF2, it runs pretty good for a NA SBC, has a jones solid roller, the aforementioned top end, scat forged crank, cunningham rods, and custom racetec pistons. Powerglide with a brake and a ATI treemaster 8" converter.

Honestly it wouldn't be what it is without this place. I've got a couple other videos too but this is the only one that shows the car leaving the line from outside.

https://www.youtube.com/watch?v=L1YoecQ1AGk&t

[77cruiser]

383 cam going in the 434?
My 421 made 550 with 9.8-1

[F-BIRD'88]

Why not lower the CR on the 383 to run pump gas.
Then you will (soon) have 2 short blocks to play with the supercharged power.

Run the low CR 383 on a single Torque Storm .
Which you can upgrade to a Dual Torque Storm setup,
later, use it on both the now boost friendly 383 and the 434 too.

[F-BIRD'88]

You've got a good car for this.
You can run both engines (progressivily) at various boost levels , using various fuels to dial up/down the power to suit the job. N/A. , low moderate boost (pump gas)
High boost on alky/ gas and or race gas and or gas+ water/meth.. Including single carb single blower.
Dual blower/ single carb, Dual blower/ twin carb or Tri carb set up. Ya you read that right. Blown- Tri Power

[xxdabroxx]

Why not lower the CR on the 383 to run pump gas.
Then you will (soon) have 2 short blocks to play with the supercharged power.

Run the low CR 383 on a single Torque Storm .
Which you can upgrade to a Dual Torque Storm setup,
later, use it on both the now boost friendly 383 and the 434 too.

We've got less than 25 passes on the 383, just got it running this year. I don't mind running E85, it's cheap enough out of the pump but it is a 30 mile drive to get it around here. It always tests good. Car is setup for it too, Teflon lines and a prostar 500. Tried to future proof the chassis to the extent possible/ reasonable. The pop the higher compression makes is welcome too.

The 383 is also a gm 010 block so I'm afraid to push it much harder. It does have billet 4 bolt mains and half filled with hard block though.

This is all thoughts for now but I'd likely get another cam ground, I doubt the 383 cam would be ideal in a low compression bigger engine but that's why I paid Jones to grind me a cam. I've read books and researched but my cam picks would be a WAG at best.

While I agree the procharger/ torque storm blowers would be a good option I really want an 8-71 sticking out the hood someday.

You've got a good car for this.
You can run both engines (progressivily) at various boost levels , using various fuels to dial up/down the power to suit the job. N/A. , low moderate boost (pump gas)
High boost on alky/ gas and or race gas and or gas+ water/meth.. Including single carb single blower.
Dual blower/ single carb, Dual blower/ twin carb or Tri carb set up. Ya you read that right. Blown- Tri Power

3 half dominators would look cool on top of a blower. Don't know that I've ever seen that though.

Really determined to go old school big belt blower on this thing for nostalgia sake even if it isn't the most optimal thing.

I was just thinking if a short block was going to sit in the corner of the garage and make the same power as what I've got now it may be worth running to be able to run local pump gas.

I think the low compression will keep me from making the same or more power though. And nobody wants to go slower. Haha.

[F-BIRD'88]

The cam you got is likely fine. It will get you started.
You can play with its installed position with the low CR and blower..
I like the 8-71 roots stuff too.
Tri Power on top.. Your current 4 bbl + a 2bbl holley in front , on a Blower carb adapter plate. 2 carbs 6 venturi, 3 fuel bowls. 6 jets Easy inline linkage
Now you got 50% MORE CFM AND 50% MORe Fuel Capacity all along with Dual fuel Strategy ready in a easy to work on format.

The only thing the car will need for sure is wheelie bars.

.010 chevy block.. Would you rather split a stock block in ½. or do the same to a $$$$ aftermarket block.

[F-BIRD'88]

Consider starting out by simply bolting on a Single Torq Storm. or bolting on a 8-71. right on your current engine. AS IS.. You WILL NOT GO SLOWER.
You do not need a new cam (yet)

[steve cowan]

Don't go to the DARK side
NA all the way

[1980RS]

Your going to need more than that old 2925 S/V to make good power on that 434. I would at least use a 300-25 Strip Dominator or better yet a S/V II that's a good intake out of the box. A larger carb will make some more power as well.

[HQM383]

Punch the numbers into some software. Something basic like Dynosim6. Should give a general idea toward answering your question.

What’s done to those Vic jr heads?