This is my first post here, be gentle...

I dont want to seem like Im looking for exact numbers and parameters to build an engine, Im just looking for general guidance for now.

What are some engine/tranny combos to get a 70' Roadrunner into the 9.5 1/4 mile range?

Im looking at building a 440/512 stroker (440 source) with an EFI system of some kind and Trickflow heads. But I am open to other options, Im here to learn.

Blow through supercharger? NOS?

If Im correct a blower motor should be built at around 8.5 compression, is that the same for a NOS motor?

NOS will like 13:1.

We need to know more about your Road Runner, to know what it takes to run 9.50. Is it mostly stock now? Weight is a key factor. B bodies car weigh between 2800lbs and 4500lbs race ready.

Where do you plan on racing it?

Denver requires more effort than Jersey.

Is this a race car or a street car? If it is a race car then you just sort out the power to weight ratio and dial in the suspension. A street car needs a lot of power to run that kind of number since the car is heavy and the suspension isn't very good.

Breaking into the 9s in CO would be fine, 9.8ish.

I want to keep it mostly stock as far as weight goes I believe. Keep all sheet metal except for the hood and keep full interior.

Very interesting, I had no idea.

Build an E85 car and add some NOS?

This is why Im asking these dumb questions.

Guesstimate of car weight?

I have no idea, I thought they would all be close. Right now it has no engine or tranny.

As Andy said, if it’s a street/strip car, you’re going to need to make more power per pound than a dedicated race car.

9.8’s in Co(Denver) in a typical race weight street/strip car(3800lbs), you’ll need more power than a stock block will live a long happy life.

I’d be shooting for 850-ish “Standard corrected horsepower”.

Thanks man. Thats right where I was thinking I would need to be on the low end of the HP rating.

I know turbos make up for the thin air up here, does NOS act the same way?

For what its worth Im leaving CO here pretty soon for the midwest.

If it helps. My stripped and race ready 1970 Road Runner with light weight everything I could get my hands on. Fiberglass doors, fenders, hood, trunk lid, and Bumpers. Lexan for windows, aluminum dash, no interior, 10 point mild steel cage and, aluminum front hubs. Plastic seat aluminum heads, manifold, master cylinder, and radiator. Dana 60 with split mono leafs, Torsion bars in front and, stock K frame. 200Lbs driver and 5 gallons of fuel = 2850Lbs. I was hoping to get 9.?? out of it with a very healthy 500" stroker.

Digger73 (Mike)

Count on not getting it right the first time, and shoot for 1,000 at least as to the hard structural parts.
Starting from scratch with minimal in-house fabrication capacity, I'd try a big Procharger and 200 nitrous.

I understand, but I really want to get the bottom end and heads correct the 1st time, I dont want to waste that much money.

What size Procharger? F1? Im fairly certain I cant drop the coin for one of their race versions.

What your asking to achieve is going to take a few $$, your going to need 800++ HP and the suspension to help make it happen.

I have been playing big blocks on and off the strip for many years.
Im running a stock block 547, Indy topped with tunnel ram in my street 71 Barracuda that comes in at 3750 lb, I have not gone 9 yet, managed a 10.1 @ 135.
I have just changed the converter to a new 5000 and the rear shocks to Viking double adjustable in the hope of running that 9

Im no turbo guru but maybe that is your answer cause I know that doing it with just carbs is not that easy or cheap.
Good luck.

Well, NA is a lot harder. If what Im reading is correct you should be able to run low 9s with a power adder of some kind?

If your lucky and skillful
Getting the mass moving quickly and efficiently is the hard part of getting a real quick 60 ft. time so it will make the high to mid nine ET in the 1/4 mile like your wanting, it will probably need to be in the mid 1.30 or quicker in the 60 fts.

Plenty of ways to go, personally I would build a mild 650>750hp 572ci motor using TF270's or -1's (ported), use a $$$$ Indy block or similar aftermarket block as at 800+hp a stock block won't last too long, do it once. Then add NOS. It doesn't have to be 13:1CR, 11:1 will work and with the right cam still be premium pump gas friendly for the street, use 1 of Dominic's sorted dominators.

At say 3800lbs race weight you'll need 875 actual track hp to go 9.50@141. Use something like Mono leafs/caltracs and some good shocks, make sure your car is stiff enough to handle the mega torque you'll have....you should only need a 200>250 shot to achieve your goal...my 2c's.

We have a guy here in UK (Tig who is a member here) who runs a 3900lbs+ Challenger with a 572 NA motor, street car interior with stereo at I believe 11.1 last time I spoke to him, .730 Roller, Caltracs/4.10's/29.5" slicks and a single Dom, has run a best of 9.6@140+, currently running 2 x Doms and 572-13's and running 9.7's still needing a bit of sorting I think.

You might want to talk to an8sec70cuda (Chip). He has a stock weight 70 'Cuda with a KB 572 that runs 9's on motor, 8's on spray. It's a street car. He has his combo figured out very well and can probably give you some pointers on the suspension and drivetrain. You would need the same, if not more power out of your engine, and like previously stated, a stock block will not live long in that environment.

Welcome to Moparts!Going low 10.0 is not that hard but that other 1/2 sec is going to be tough.

Dizusters 360 turbo car can easily run 9.80s@ 3750lbs, 3.55 gear, drag radials.
Doug

What's the budget for this effort?

12 to 15,000$ I would think

Your typical B body like you're describing will likely be around 3700-3800 lbs. You'll need a REAL 825+ HP at the flywheel to run the number you want.
You can build a stout, but streetable, 512 and hit it w/ a 200 shot every now and then to go mid 9s.
Or go big or go home w/ the 512 and put some decent compression in it, E 85, and bigger heads than the Trick Flows, nasty roller and try to go mid 9s on motor. Either way, the stock block will be a time bomb.
Or do like I did and get a strong aftermarket block and build a big, but streetable, 572" motor that'll run mid 9s all day at 3800 lbs on pump gas.

Assuming it's a stock car, but with appropriate chassis and wheel/tire upgrades to handle the extra power, I would think you will need at least 850hp to get you mid 9s. Late 90's I ran mid 10s in a stock steel body and full interior 68 charger. Had a Indy headed 451 that made about 730hp. No cage, 8 3/4 w 4.30 spool, 5200 converter, 8" steel wheels w ET streets.

find his combo and copy it

Looked at a few numbers today.

The correction factor from sea level to 5000’ is about 1.05 for ET, so a 9.50 is close to a 10.0 @5000’.
The Moroso chart shows 825hp for a 9.50@3800lbs, and “most” cars need about 10% more power than indicated to get it done.
I’d be shooting for 900hp if that’s really the target ET.
Less weight = less power req’d.

Basically, that ET is about 4.6lbs/hp if the car is sorted out.

Here is a picture of my 70 GTX which is same body as 70 RR.
It has a Chenoweth built 493 stroker with Indy SR heads. You will need more with all the street goodies on the RR.
MJ

A motor combo in another thread is a good thing point:

Who has a good cam recommendation for a 572 with indy 345 cnc 2.25 intake 181 exhaust heads. Indy tunnel ram with to alky 750 carbs. 14.1 compression with diamond flat tops. 4.500 bore 4.500 stroke.

I dont really have a budget, I was hoping for 10-12K for the engine or so plus whatever power adder I go with.

From the sounds of it, I might build this to a 10.5 street car and pick up a lighter car for racing.

NA?

Yes, 1050 carb with Indy intake.
MJ

I dont really have a budget, I was hoping for 10-12K for the engine or so plus whatever power adder I go with.

From the sounds of it, I might build this to a 10.5 street car and pick up a lighter car for racing. [/quote}


10-12K isn't even close with new parts for a 900 hp 572. Mine was built from a combo of used and new. If all the parts were new it would be close to 20K. It'll run 9.20@145 at 4500 D/A, 9.0@150 at 1200 D/A. A dominator and single 4 might be a little quicker. 3340 race ready. The Turbo Late Hemi or SB stuff should get it done cheaper.
Doug

Doug, I drool every time I see that pic.

The easiest, best, AND cheapest way would be with one or more turbos. Especially if you want to actually be able to drive it on the street too.

Haha, yeah, not Mopar under the hood...

For the record, building a 572 or an after market block was never in any of my plans.

This was linked to me from some where, but I cant find who posted it. Anyways, what about a setup close to this with a 512" motor and EFI?

https://www.hotrod.com/articles/mopp-0604-440-mopar-engine-build/

And I also read these original blocks can hold more power if the engine is "boosted", is that true?

What does someone charge to fab something like that up? I dont have the welding and fab skills for anything close to that.

I'd run a Late Hemi with a turbo. Stock block and forged crank will hold 1000 HP w/o issue. Stock heads are very good. aftermarket piston/rod for boost. Use a knock off Drag Pac intake. 20 psi should get it easy.
Doug

That’s the future right there.

these original blocks can hold more power if the engine is "boosted", is that true
Yes, the cylinder pressure "spike" (BMEP) is lower and more widely distributed than equivalent HP NA.

Many successful turbo race cars don't use fabricated tube headers, but simply use modified stock cast-iron manifolds upside down, reversed front to rear etc. Google around for 1968-70 B/RB manifold choices on turbos including truck, C body etc.

https://www.google.com/amp/s/www.hotrod....rbocharger/amp/

This is friends Dart. Since the article he has had to make quite a few upgrades as he bent the Dana 60 and the bars holding it in the car! As I recall he's been 8.20's.

It's a very mild setup and he drives it all over Wichita.

I have another local friend that parts SRT-8 cars with the 6.1 and an early A-body 'Cuda with this engine and a turbo will be my next project.

the mythical van BB manifold that you can turn upside down and still put in spark plugs

https://photos.app.goo.gl/UKNYUsEDbEjBAX2b6

https://photos.app.goo.gl/jqp6VFMLvpqT14Bd7


late 50's manifold with generator provision, something I may someday try on a BB single turbo car

https://photos.app.goo.gl/iBbqSgEdoPytKuBg6

on the right, 64/65? BB manifolds that exit behind the last port, might work swapped side for side depending on steering/a arm config

https://photos.app.goo.gl/6JKnRkjkHVd1xSPV9

If you want to run NA then you better get a LOT
lighter than you are.. more than likely you
better get lighter than you think

https://www.google.com/amp/s/www.hotrod....rbocharger/amp/

This is friends Dart. Since the article he has had to make quite a few upgrades as he bent the Dana 60 and the bars holding it in the car! As I recall he's been 8.20's.

It's a very mild setup and he drives it all over Wichita.

I have another local friend that parts SRT-8 cars with the 6.1 and an early A-body 'Cuda with this engine and a turbo will be my next project. [quote/]

That thing is BAD!

Im running a power adder

That's what I would do. Well that is what I would do if I did it again

Here is mine on its first run 9.7
500 inch
Procharger


https://www.youtube.com/watch?v=jqMdxvWYyq0&ab_channel=RobKamstra

I needed more injector as I ran it to a 100% duty cycle and the MAP at 100%
Need to head back to see how it does

Sweet car!

Thats almost exactly what Im looking to build, there is hope after all.