300hp 307

[84 W40]

Do you have a part # for the Edelbrock heads that will work?

What ever the current part number that Edelbrock is using, don't have that number. You can use big block heads on a small block olds but need custom pistons to make up for compression. C and D olds heads that was used in G block 400 had intake valves that were 2 inch or larger.

 

[84 W40]

Hahaha. long stroke 400...the 307 of the big block Olds. Actually, it was one of the worst bore to stroke ratios ever, even worse than the 307. But it shared crank/rods with the 455. Just had a smaller bore. Like the 307, which shares the same rods and stroke as a 350 (307 crank is lighter, though) it was for better emissions. How I hated that engine. Spinning rod bearings on it was no fun.

For a small bore big block it made decent power but didn't like high rpm, ask me how I know.

 

[69hurstolds]

For a small bore big block it made decent power but didn't like high rpm, ask me how I know.

You and me both. That's how I spun a rod bearing. 4-speed 69 442, missed a power shift to 3rd and....clackity clack clack clack....fudge.

Which reminds me...I bought a new fuzzy gold Hurst handle for that shifter way back then...still got it - new in the packet. Probably need to sell it for a pretty penny. I'd use it on the 69 H/O's dual gate but it's got the fine threads, not the coarse ones like on the dualgate handle. Best used for a 4 speed.

 

[83MonteCarloSS]

What is your reason for wanting 300hp?

For a street driven car wanting more fun I would shoot for the most torque you could get out of it instead of the most horsepower. Especially if you’re wanting to keep the small cube motor emissions legal with no power adder.

 

[MadDrOlds]

What is your reason for wanting 300hp?

For a street driven car wanting more fun I would shoot for the most torque you could get out of it instead of the most horsepower. Especially if you’re wanting to keep the small cube motor emissions legal with no power adder.

I agree with you. I’d say there is no “magic” to the 300 hp number, but it seemed like a reasonable compromise for discussion triangulating between “currently anemic” “scary for the application” and “impossible”.

Maybe my original post should have said “how could you approach 300hp”. If I now say 280 was ok, I’ll be accused of moving the goalposts again …

 

[Clone TIE Pilot]

What is your reason for wanting 300hp?

For a street driven car wanting more fun I would shoot for the most torque you could get out of it instead of the most horsepower. Especially if you’re wanting to keep the small cube motor emissions legal with no power adder.

HP is just torque × RPM ÷ 5,252. The 5,252 is a factor of 33,000 ( the amount of ft/lb of work per minute in one HP) ÷ 2 × Pi. Basically an engine can mainly make higher HP though either a lot of torque or high RPM, but generally not both. This is why low torque engines need to rev and high torque engines don't like to rev so much. The torque and HP curves always cross each other at 5,252 RPM, really is a magic number for engines. Increasing flow can increase torque output but also rasies the peak torque RPM which can affect driveability.

 

[84 W40]

You and me both. That's how I spun a rod bearing. 4-speed 69 442, missed a power shift to 3rd and....clackity clack clack clack....fudge.

Which reminds me...I bought a new fuzzy gold Hurst handle for that shifter way back then...still got it - new in the packet. Probably need to sell it for a pretty penny. I'd use it on the 69 H/O's dual gate but it's got the fine threads, not the coarse ones like on the dualgate handle. Best used for a 4 speed.

Had the same outcome spun a bearing and bent one rod.
Going back to the original question, yes you can get 300 hp out of 307 if you have deep pockets. What a few owners that had a Hurst or 442 back in the 80s into the 90s did was add nitrous, small shot of it. What I did with my 86 442 back in 89 was replaced the 307 with a olds 350 that was built for the street and some track use. It wasn't legal at the time nor its legal today in some States but it was more cost effective to do it that way.

 

[RabbitHoleSS]

Oldsmobile 307 Engine - Analyze This! - Popular Hot Rodding Magazine

Read about the Oldsmobile 307 Engine and see pictures as it gets built under an impossibly small budget with an Edelbrock Performer RPM intake manifold, Ross custom pistons, and MSD ignition, inside Popular Hot Rodding Magazine.

www.motortrend.com

Are aftermarket olds heads not an option anymore?

The 2.07/1.68 valve size in the soon to be released 68cc version of the Edelbrock head will hit the side of the bore on a 307. There is another solution that would easily hit 300 HP but like everything Olds, isn't cheap or easy. It involves the 4" stroke forged 5140 stroker crank. Cutlassefi(Mark Remmel) is getting a batch done shortly. They will be cheaper at $1200 vs his current billet offering. It is designed with a light bob weight so expensive Mallory isn't need to internally balance, a small amount usually needs some removed on the 350 strokers. Factory 330 cranks need 4 or 5 slugs to internally balance with modern aftermarket rods and pistons. That pretty much pays for the stroker crank. It is designed to use LS rods and would need custom pistons in the smaller bore more than likely. That would give 370ish cubic inches. You could probably hit 350 HP/TQ easy even with CCC and stock looking exhaust. You could up compression and cam size slightly and still work. It could still look stock, running factory heads and block. Honestly if I got an orginal H/O or 442, I would go that route. These cars are too rare and valuable these days to make them not look orginal.

But then again, to do all that wouldn't you start with a 350 block?
Is this something your seriously considering?

 

[CopperNick]

One potential not so True dual option, with the major caveat that you would need THREE O-2 sensors; calls for each head pipe or header collector to have a sensor and it located before the cat(s), and the third located in the "H" or equalizer pipe located post cats. This is the set up that I have in my S-10 and it mimics what the factory issued to the point that the computer is happy. The thing here is that the CPU has to possess software that is capable of analysing the pre-cat and post-cat sensor input and making timing and ignition changes accordingly.

After the H pipe, each side is piped independently to the rear bumper. The only point of interaction is the H pipe and they, or an X pipe, are as much for exhaust equalization and they are for anything else.

As for the dia of the exhaust, for that you need a specialist who understands the effect of diameter on velocity as it pertains to exhaust A skinny bore 307 might not be able to make much use of a 3" or larger dia exhaust system; it is just not pushing that much waste down and out.

This is beginning to sound more and more like a case of "how to get the best bang for my buck out of a bunch of low-po leftovers". The Law of Diminishing Returns states that once a certain point is reached, no matter how much more you invest in a project, the return on your investment will continue to shrink. I am suggesting that your 307, even just as a bench racing exercise is not all that good an investment excercise, simply because whatever you chose to put into it will never be reflected by what the motor gives up for power/torque in return. Otherwise put, and already noted above, you can get there, aka a 307 Horse/307 Cid, but the cost to do so is not worth the train-ride.




Nick

 

[69hurstolds]

I agree with you. I’d say there is no “magic” to the 300 hp number, but it seemed like a reasonable compromise for discussion triangulating between “currently anemic” “scary for the application” and “impossible”.

Maybe my original post should have said “how could you approach 300hp”. If I now say 280 was ok, I’ll be accused of moving the goalposts again …

I watch goalposts. It's what I do.

300 is very doable with a pocket full of $$. It's just doubtful you can do it and STILL maintain a scrutinous application of the emissions part of the deal. In otherwords, while you may pass the sniff test with dual cats and exhaust, which will give the 307 a tad of spinach, you're very likely going to fail a visual right out of the gate. You can still run the old ECM with just one O2 sensor and get the proper feedback for the carb and such. Probably. While it's good to think about ways to maximize power and efficiency, it's a lot tougher starting with a 307 to get there.