Modern Chevy 302 build

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Reborn756

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Howdy folks, here's another question (and the main reason I signed up here).

So, the 305 that's currently in my Trans Am is on its way out. Russian circus bears are better mechanics than the rednecks that put it in the car. coolant hoses loose, wire harnesses melting on the manifolds, plenty of flakes in the oil, even after we changed it. You get the idea. So what I want to do is get a 350 block and destroke it down to a 302, or to a 305 if the block needs bored (.020 overbore will put it at 305 cubes). How I intend to do this is by taking a late 86s L98 block with the one piece main seal and putting the crankshaft from an L99 v8 in it. If I use the 5.94 inch PM rods from the L99 as well, I can also use standard 350 pistons. I already have everything in terms of rotating assembly figured out. My question for you folks is what should I do for the rest of the combo to reach my desired power numbers? I'd like to put this sucker at 400hp/400ft lbs if at all possible. It will need to run a reasonable street powerband, so no crazy cams like the old 30-30 duntov. It also needs to run on 87 octane, so I'd prefer to keep compression at 9:1. I'm going with new heads and everything, so feel free to give your input on those as well. I would like to go with a Hydraulic roller cam if possible. I will not be using any power adders for this build.

I've put this up on the third gen forums awhile ago, and got some good help from those folks. I recently put this up on Chevytalk, but the fellas over there are still trying to talk me into a cookie cutter 383. Here's to hoping you folks will be of some good help too!

Thanks in advance everyone!
 
Well I am no expert in anything, I am defiantly not your go to guy when it comes to what parts work best with each other to increase horse power and torque.

This being said if you want a so called modern day 302 why is that?
From what little information I can shake out of my cob webbed brain about the original high RPM capable 302 it was created out of necessity to compete in racing where requirements limited cubic inches to 305 CI.

This motor was right at home in a light weight Camaro and did very well for what it was built for.

This being said the original 302 had 11 to 1 compression ratio and needed high octane fuel.

The 302 from days long ago enjoyed higher RPM but lower torque numbers because of being destroked.

again I am no expert, why is it that you think you can build a lower compression Naturally aspirated small block that will out perform the original 302? especially on 87 octane.

As George Bush once said " Its fuzzy Math "

Help catch us up to where your at and perhaps the light bulb will light up illuminating the missing link that you desire.


I Personally think anything that you can do to a small block Chevrolet engine has been done over and over and over.

I am sure if your somehow successful in building your dream Modern day 302 that really isn't modern, it would still be considered a cookie cutter engine by today's custom car and engine standards.

Do not get me wrong I love me a small block Chevy and I love your concept.
I am also not intending to pop your bubble.

But I am saying if you want something different out of a small block Chevy engine you will have to break out of the box. WAAAAAAYYYYYYY out of the box.

Personally If I had your Pontiac and I wanted something different I would put a Pontiac engine in it.

A Pontiac engine could easily reach your requirements for horsepower and torque yet be mild enough for a daily driver. but forget about 87 octane.

Again I am no expert, I also mean no disrespect to the time and energy you have invested in dreaming this build up.

We all want to march to the beat of a different drummer, and to stick out as a visionary coming out with the unheard of.

Its people like you with the determination and will power that will make something new and creative happen and perhaps change the way engines are built. So keep up the quest and keep us up to date if you make any ground breaking discoveries in the small block Chevy world.

Years ago I was on a quest like yours wanting to invent something better, something different yet I never had the education or money to do anything with my idea.

Instead of trying to make crazy horsepower and torque with a traditional internal combustion engine.

What if we redesigned the transmission torque converter and rear axle and front hubs of the basic car.

In my mind you would have once built a hybrid but not for fuel economy but for pure unadulterated speed and acceleration.

You would have 4 electric motors one on each wheel that could disengage ( freewheel with no parasitic drag when the power is not called for at that particular time ) or be used for regenerative braking to recharge the batteries. the torque converter would also have a electric motor built into it to also assist the gas engine.

It would require one insanely complex controller, in drag race mode using traction control software you could leave the line with the benefit of all the electric motors and the gas engine. making for one neck snapping take off that no one would see coming. From under the hood you would just see a normal run of the mill cookie cutter engine using 87 octane pump gas.

with the electric assist motors a much taller final drive gear ratio could be used for a higher top speed and get to that speed much faster.

I cant see something like this used for road course racing or anything because the batteries would quickly get depleted.

I think this would be a great way to reinvent drag racing or all out speed record attempts at the salt flats.

It would for sure would make on heck of a sleeper.
 
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Thanks for the reply EAOutlaw!

Small Block 350s have been pushed to ridiculous amounts of horsepower and torque while still maintaining a good street powerband and running on garbage pump gas. All I'm proposing is destroking one of these built engines to get to 302 or 305 cubic inch, which will not only surprise plenty of other 3rd gen TAs/Camaros/mustangs, but also get better fuel mileage than its 350 counterpart, due to requiring a lower CFM to run properly. The reason I'm looking for help with this is I don't know what the rest of the combo will need to look like in order for me to hit my numbers while staying within a reasonable powerband and staying on pump gas.

As for a pontiac motor in a 3rd gen, I've thought about this, but plenty of people have already went this route. Nasty cars, but I want something a little different. I've never heard of a 3rd gen Chevy 302 anything.
 
You are not going to get 400 horse power running a compression of 9:1 with a streetable cam naturally aspirated out of 302 CID!
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Again I can not stress this enough, I am no expert or horse power guru,However from the little I do know, there is no replacement for displacement.

It is my opinion that a L98 engine like any engine has limitations. and if your going the naturally aspirated route. and you want higher horse power than stock, higher torque than stock. You need to increase compression, increase the amount of air and fuel going through the engine, and to maximize the potential energy from each power stroke of each cylinder.

Destroking the engine is just making a shorter stroke which causes less air and fuel getting into the engine, which means to make up for it you need higher compression than your would with a the same engine with a longer stroke. higher compression means higher octane fuel.

Also to obtain a higher RPM that you will be wanting to make up for the shorter stroke you will want a solid lifter.

All the key points that you have dug your heels in wanting is the very points that will keep you from the end result.

If you want a high RPM small block with a shorter stroke something has to give.

it is my opinion that to get the result you want from a L98 or any engine learn from the people whom do this all day everyday.

Going by experience this group of people on this forum is not the best outlet for secrets to unlocking power from a Small Block Chevy engine.

the only way that you will get the numbers you are looking for is through higher rpm much higher than they made with the original 302.

and I am sure you will never get there with 9 to 1 compression low octane fuel low lift cam and Hydraulic lifters.

Again it my opinion not gospel but the key points you want will not likely get you the performance you want. regardless of what heads and intake you use.

You claim people have made a massive amount of horsepower and torque using 87 octane pump gas, I have to call BS on that.

Feel free to post sources facts and figures right now all I am hearing is someone whom wants a bench top dyno argument.

please catch us all up on your level of expertise and I will be happy to eat my words.
 
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