can anyone tell me what engine family the 365 ci r5p7 mopar nascar engine is from. im wanting to run one in a gasser for drag week (not this year, obviously) and the engine family has to be pre 1968. any help is welcome

 

I'm assuming you're referring to the type of racing and not what you wear while racing. What type of chassis are you running? How much work do you want to put into the power plant? I haven't followed NASCAR since the mid 70's when the "stock" part went away. The 426 Hemi came out in '64 and in cars in '65 The big block motors up to 440 were out before '68. Some of the LA engines came out, the 273, in 1964 or '65. The A engine were developed from the Dodge 241 Hemi in '53. Personally, I'd go with the 440. I always like the BB engines and the raised deck with give a little more power. There is still plenty of support for the BB engines. The Hemi's are also very successful. The Kieth Black version even has a GM part number even though it's a Chrysler design. It's also the most powerful and most expensive.

 

im using a scottrods 1933 ****** coupe gasser rolling chassis with a fiberglass body. im wanting to get a high revving motor that can run on pump e85 for less than 20-22k

 

I've built engines but never very many and it's been 20-25 years since I built one. I'm sure technology has moved on. I've always preferred torque over horsepower but most of my racing was road racing. At first thought, I'd go with a big block but you get into issues with reciprocating mass. Aluminum alloy pistons will help there but a smaller engine can rev higher with less parasitic loss. In the past, I always reinforced street cars for racing, I've never used a dedicated race chassis. The light weight may bite you on the boo boo when you add a lot of torque. What gears are you planning to use? A 440 is good at low end but the 426 Hemi is better when you wind it out.

Back in the mid 70's, there were two brothers who raced locally. One ran a 440 and the other glommed onto a 426. The 440 usually won on 1/8 mile tracks but the 426 usually won on 1/4 mile tracks. It was usually a close thing either way. Your gearing, total chassis weight will probably decide for you what engine to run. I'm a believer in "There's no replacement for displacement" but I've seen small engines walk away from more ponderous larger engines too.

 

im probably use 3:73 or 4:10 rear gears and i would love to do a big block but i want to do 8-9k rpms and not spend a million dollars. i also want to do 800-950 hp with a cr of 14:1 or less for pump e85 since the amount of ethanol varies so much

 

They have been around for a while and recently changed format and I don't watch much but head over here; https://www.powernationtv.com/ They have one show that doesn't almost nothing but engines. The old format had a message board. I don't know if the new one has it as I never signed up on it. I just look at the schedule when I think of it. My engine building experience is so out of date, I'd rather see you spend your money on more recent technology.

 

it was a great source but they only had a 500hp 440 and a 360 magnum with 600hp. do you know of a place that makes hemi heads for big block fords or bbc

 

All my old sources are either retired (or dead) or got bought out. It's been so long since I raced or wrenched, I may not give you the best advice to be competitive. If you aren't there to win, why waste your time and money. I'm sure there are companies out there that make retrofit parts. If Hot Heads is still around, you can try them.

 

I follow drag week. The gasser class runs 8's. Mike Finnagen has a 55 Chev with a blown hemi who won in 2019.
the R5P7 is a new design. Nascar only said it needs a stock bore space. Dart from dragweek 2019
If you want a competitive class car its expensive. You might need to contact them to see what is legal as an engine. Cheapest would be a Chevy big block.

 

does anyone know how much boost a stock 426 hemi can handle. hot rod took a stock crate engine and made 750 hp with just a weiand 8-71 blower kit. i was thinking about doing that but with e85 and a bigger cam made more for boosted applications